PLAB 1 (UKMLA AKT) infection & sexual health questions

A NEWS2 score of 7 or more indicates a high risk of clinical deterioration and mandates urgent clinical review by a clinician with critical care competencies, typically at least at specialist registrar level, along with continuous monitoring. In a postoperative patient with fever, tachycardia, tachypnoea, hypotension and new confusion, sepsis must be actively considered and the Sepsis Six pathway initiated without delay. Delaying escalation for further investigations such as imaging risks deterioration to septic shock. Early senior involvement and treatment within the first hour of recognition improves survival according to NICE NG51 and Surviving Sepsis Campaign guidance.

• A. Investigations should run in parallel with, not before, urgent escalation and treatment.
• B. Symptomatic treatment alone ignores the high-risk NEWS2 score and possible sepsis.
• C. A score of 9 requires immediate action, not deferred review in 12 hours.
• E. A routine outpatient referral is far too slow for a patient with a high NEWS2 score.

The Sepsis Six bundle consists of six actions to be completed within one hour of recognising sepsis: give high-flow oxygen if required, take blood cultures, administer intravenous broad-spectrum antibiotics, give an intravenous fluid bolus, measure serum lactate, and monitor hourly urine output (with catheterisation if needed). This bundle aims to identify the source, support organ perfusion, and reduce the time to effective treatment, which is strongly linked to improved survival. Imaging, central lines and ICU admission may be required subsequently but are not part of the core one-hour bundle. Oral antibiotics and fluids are inadequate in a hypotensive, tachypnoeic patient with likely septic shock.

• B. Oral antibiotics and fluids are insufficient in a hypotensive patient and are not part of the bundle.
• C. Imaging and central line insertion are not core Sepsis Six actions and should not delay the bundle.
• D. CT abdomen is not one of the six core actions and should not delay antibiotics or fluids.
• E. ICU referral may follow but is not one of the six defined one-hour actions.

Neutropenic sepsis, defined as a neutrophil count below 0.5 × 10⁹/L with fever or signs of sepsis in a patient receiving anticancer treatment, is a medical emergency requiring immediate empirical broad-spectrum antibiotics, ideally within one hour. Piperacillin with tazobactam is the first-line agent recommended by NICE because it covers both Gram-negative organisms (including Pseudomonas aeruginosa) and Gram-positive organisms, which can rapidly cause life-threatening infection in neutropenic patients. Narrower agents or those lacking adequate Gram-negative or Pseudomonal cover are inappropriate as sole initial therapy. Antibiotics should not be delayed pending the neutrophil count result if neutropenic sepsis is suspected clinically.

• A. Vancomycin alone lacks Gram-negative and Pseudomonal cover needed for empirical therapy.
• B. Ciprofloxacin alone is not broad-spectrum enough and is not first-line for empirical treatment.
• C. Metronidazole only covers anaerobes and is not appropriate as sole empirical therapy.
• D. Amoxicillin has insufficient Gram-negative and no Pseudomonal cover for neutropenic sepsis.

Septic shock is defined as sepsis with persistent hypotension requiring vasopressor support to maintain a mean arterial pressure of 65 mmHg or above despite adequate fluid resuscitation. Noradrenaline is the first-line vasopressor recommended by the Surviving Sepsis Campaign because it increases systemic vascular resistance and blood pressure while causing relatively less tachycardia than adrenaline. Further fluid boluses are unlikely to improve perfusion once adequate resuscitation has failed to restore blood pressure, and may worsen pulmonary oedema. Hydrocortisone is reserved for patients with ongoing shock despite adequate fluids and vasopressors, not as a first-line measure.

• B. There is no indication of anaemia or haemorrhage requiring transfusion in this scenario.
• C. Diuretics would worsen hypotension and are inappropriate in hypoperfused shock.
• D. Repeated large fluid boluses after adequate resuscitation risk fluid overload without correcting shock.
• E. Hydrocortisone is used as an adjunct in refractory shock, not as first-line treatment before vasopressors.

Staphylococcus aureus bacteraemia carries a significant risk of metastatic infection, including infective endocarditis, even in the absence of a murmur or other classical signs, and all cases should prompt specialist review. Current UK practice guided by BSAC and local microbiology recommends echocardiography (transthoracic as an initial screen) in patients with S. aureus bacteraemia to identify endocarditis, particularly given its associated high mortality if missed. Repeat blood cultures should also be taken at 48–72 hours to confirm clearance regardless of clinical improvement, but this does not replace the need for cardiac imaging. Discharging without investigating the source or risk of endocarditis risks missing a life-threatening complication.

• B. Discharge without further assessment risks missing endocarditis or other complications, which carries high mortality if untreated.
• C. Antibiotic treatment alone without imaging risks missing endocarditis, which changes duration and choice of therapy.
• D. Fever recurrence is not a reliable marker, and repeat cultures at 48-72 hours should be done regardless, alongside echocardiography.
• E. An abdominal ultrasound is not the priority investigation; the main concern is cardiac source via echocardiography.

This patient has low-severity (CURB-65 = 0) community-acquired pneumonia, most commonly caused by Streptococcus pneumoniae. NICE guidance recommends a 5-day course of amoxicillin as first-line therapy for low-severity CAP in patients without penicillin allergy. It has a narrow spectrum, good oral bioavailability and reliable activity against the typical pathogens responsible for low-severity CAP. Macrolides or tetracyclines are reserved for penicillin-allergic patients or when atypical organisms are suspected.

• A. Doxycycline is an alternative in penicillin allergy, not the first-line choice.
• B. Clarithromycin is used for penicillin-allergic patients or atypical pathogen cover, not first-line in low-severity CAP.
• D. Levofloxacin is reserved for penicillin allergy or more severe CAP, not first-line for low-severity disease.
• E. Co-amoxiclav is reserved for moderate-to-severe CAP or specific risk factors, not low-severity disease.

Mycoplasma pneumoniae typically affects young adults and presents with a dry cough, headache and malaise, often with a chest X-ray showing bilateral patchy infiltrates disproportionate to the relatively mild clinical signs. Extrapulmonary manifestations are characteristic, including erythema nodosum (the painful shin nodules described) and cold agglutinin-mediated autoimmune haemolytic anaemia. Diagnosis is often supported by Mycoplasma serology or PCR, and treatment is with a macrolide or tetracycline since Mycoplasma lacks a cell wall and is resistant to beta-lactams.

• A. Chlamydophila psittaci is linked to bird exposure and typically causes hepatosplenomegaly rather than erythema nodosum or haemolytic anaemia.
• B. Legionella pneumophila is associated with travel, water sources, hyponatraemia and gastrointestinal symptoms, not erythema nodosum or cold haemolysis.
• C. Streptococcus pneumoniae causes a more acute, lobar pneumonia and is not typically associated with erythema nodosum or haemolytic anaemia.
• D. Haemophilus influenzae typically affects patients with underlying lung disease and does not cause these extrapulmonary features.

This patient has an infective exacerbation of COPD, indicated by increased sputum purulence (green, thicker sputum) alongside worsening dyspnoea, which is the key criterion for starting antibiotics according to NICE guidance. Increased sputum purulence is the single most reliable marker of bacterial infection in this context and justifies oral antibiotic therapy (such as amoxicillin, doxycycline or clarithromycin) without needing to await further investigation. Oral corticosteroids may be added if breathlessness significantly affects daily activities, but antibiotics are the key omission here given purulent sputum. Hospital admission is not indicated as the patient is not hypoxic, tachypnoeic beyond mild limits, or systemically unwell.

• A. Admission is unnecessary as the patient is stable with oxygen saturation of 94% and only mild tachypnoea.
• B. Delaying treatment risks worsening of a bacterial exacerbation that meets criteria for antibiotic therapy.
• C. A chest X-ray is not required before starting antibiotics for an uncomplicated infective exacerbation of COPD in primary care.
• D. Steroids alone are insufficient as purulent sputum indicates bacterial infection requiring antibiotic cover.

The combination of chronic cough lasting more than 2 weeks, night sweats, weight loss, haemoptysis and upper lobe cavitation on chest X-ray is classic for post-primary pulmonary tuberculosis, particularly in a patient from a high-prevalence country. Mycobacterium tuberculosis preferentially affects the upper lobes due to their relatively higher oxygen tension, which favours growth of this aerobic organism. Diagnosis requires sputum samples for acid-fast bacilli smear, culture and nucleic acid amplification testing, and the patient should be isolated pending results given the risk of airborne transmission. This presentation should not be mistaken for the more acute course typical of bacterial pneumonia or lung abscess.

• A. Bronchogenic carcinoma can cause haemoptysis and weight loss but would not typically present with night sweats and cavitating consolidation in this epidemiological context.
• B. Lung abscess typically presents more acutely with foul-smelling sputum and is less associated with the chronic systemic symptoms and classic upper lobe cavitation described.
• C. Community-acquired pneumonia has an acute onset over days, not the subacute 6-week course with weight loss and night sweats described here.
• E. Bronchiectasis causes chronic productive cough but is not typically associated with cavitation or marked systemic weight loss and night sweats of this nature.

Ethambutol is associated with dose-dependent optic neuritis, presenting with reduced visual acuity and impaired red-green colour discrimination, as described in this patient. Because this adverse effect can be irreversible if not detected early, baseline visual acuity and colour vision testing (such as Ishihara plates) should be performed before starting ethambutol, with ongoing monitoring during treatment, particularly in patients on higher doses or with renal impairment. On recognising optic neuritis, ethambutol should be stopped immediately and an ophthalmology referral arranged, as most cases improve on cessation of the drug.

• A. Pyridoxine is given to prevent isoniazid-induced neuropathy and does not cause optic neuritis.
• B. Pyrazinamide is associated with hepatotoxicity and hyperuricaemia, not visual disturbance.
• C. Isoniazid is more classically associated with peripheral neuropathy, not optic neuritis.
• E. Rifampicin is associated with hepatotoxicity and drug interactions, not optic neuritis.

In individuals with a history of BCG vaccination, the interferon-gamma release assay (IGRA) is preferred over the Mantoux test because BCG can cause false-positive Mantoux results due to cross-reactivity with shared mycobacterial antigens, whereas IGRA uses antigens specific to M. tuberculosis (ESAT-6, CFP-10) not present in BCG. NICE guidance recommends IGRA, either alone or after an initial Mantoux, particularly in previously vaccinated contacts. Sputum tests are used to diagnose active, not latent, disease and this patient has no symptoms or radiographic abnormality suggesting active TB. CT chest is not a screening tool for latent infection.

• B. Used to diagnose active TB, not latent infection.
• C. Mantoux is less specific in BCG-vaccinated individuals due to cross-reactivity.
• D. Used to diagnose active TB, not latent infection.
• E. Not indicated for latent TB screening; chest X-ray is already normal.

Anosmia (loss of smell) is a relatively distinctive feature of COVID-19 compared with influenza, which more typically presents with abrupt onset of high fever, severe myalgia, headache and sore throat without prominent smell disturbance. Dry cough, fever and fatigue are common to both infections and do not reliably distinguish them. While household contact supports a viral respiratory illness, it does not differentiate the specific pathogen. Current UK guidance still recommends isolation and testing when COVID-19 is suspected based on such symptoms, particularly anosmia, to guide infection control.

• A. Non-specific and common to both infections.
• B. Common to both infections.
• C. Common to both influenza and COVID-19, not discriminating.
• E. Indicates transmission but not which virus is responsible.

Nitrofurantoin is first-line for uncomplicated lower UTI in non-pregnant women with normal renal function (eGFR ≥45 mL/min/1.73m²) per NICE/BNF guidance, alongside trimethoprim if local resistance is low. It is concentrated in urine, achieving high urinary levels with minimal systemic absorption, and remains active against most common uropathogens including E. coli. Co-amoxiclav, cefalexin and ciprofloxacin are reserved for complicated infections, pyelonephritis or when first-line agents are unsuitable, due to concerns about broader-spectrum resistance selection and, for ciprofloxacin, tendon and C. difficile risks. Doxycycline has no role in uncomplicated UTI treatment.

• A. Broader spectrum agent reserved for second-line or complicated UTI.
• B. Fluoroquinolone reserved for pyelonephritis or resistant organisms due to adverse effect profile.
• C. Second-line agent, not first choice for uncomplicated cystitis.
• E. Not used for uncomplicated UTI; lacks reliable activity against typical uropathogens.

Trimethoprim is a folate antagonist and should be avoided in the first trimester due to a theoretical risk of neural tube defects and other congenital malformations associated with folate antagonism during organogenesis. Nitrofurantoin is generally used in the first and second trimesters but avoided at term due to a theoretical risk of neonatal haemolysis. Amoxicillin, cefalexin and pivmecillinam are considered safe throughout pregnancy when sensitivities allow, and are used based on culture results. Clinicians should always check local microbiology sensitivities and the BNF for pregnancy-specific prescribing advice.

• A. Used safely in first/second trimester; avoided only near term.
• B. Safe throughout pregnancy when organism is sensitive.
• C. Safe throughout pregnancy when organism is sensitive.
• E. Safe throughout pregnancy when organism is sensitive.

Asymptomatic bacteriuria in pregnancy is treated with a course of antibiotics guided by culture sensitivities, unlike in non-pregnant adults where it is typically left untreated. This is because untreated bacteriuria in pregnancy carries a significantly increased risk of progression to acute pyelonephritis, as well as association with preterm labour and low birth weight. Simple reassurance or fluid advice would be appropriate in a non-pregnant woman but is inadequate in pregnancy given these risks. Renal ultrasound and intravenous antibiotics are not indicated for an asymptomatic patient with a single positive culture.

• A. Unnecessary and disproportionate for an asymptomatic patient.
• B. Appropriate for non-pregnant adults, not pregnant women, who require treatment.
• C. Insufficient; antibiotic treatment is required in pregnancy.
• E. Not indicated without symptoms or recurrent infection.

Bacteriuria is almost universal in patients with long-term catheters and does not require antibiotic treatment in the absence of systemic symptoms such as fever, rigors, new confusion, or loin/suprapubic pain, as this represents colonisation rather than infection. Treating asymptomatic catheter-associated bacteriuria risks selecting for resistant organisms and causing adverse drug effects without clinical benefit. If the catheter is due for routine change, this can proceed as planned, but this alone does not necessitate antibiotics. Cloudy or malodorous urine alone, without systemic or localising symptoms, is not an indication for treatment or further culture-driven escalation.

• A. Reserved for signs of systemic sepsis, which are absent here.
• C. Catheter change may be appropriate routinely but antibiotics are not indicated without symptoms.
• D. Not indicated in an asymptomatic, haemodynamically stable patient.
• E. Unnecessary; asymptomatic bacteriuria does not require antibiotic decision-making based on repeat culture.

Acute bacterial prostatitis requires a prolonged course of an antibiotic with good penetration into prostatic tissue, and a fluoroquinolone such as ciprofloxacin for 2-4 weeks (commonly 28 days) is recommended by NICE and BNF guidance due to its favourable tissue penetration and activity against typical Gram-negative uropathogens. This contrasts with simple cystitis, which is treated with short 3-day courses of agents like nitrofurantoin or trimethoprim that do not achieve adequate prostatic tissue levels. Fosfomycin as a single dose is used for uncomplicated cystitis, not prostatitis. The prolonged duration in prostatitis reflects the difficulty of achieving bactericidal concentrations within the fibrous, poorly vascularised prostate gland.

• B. Single-dose regimen for uncomplicated cystitis, not prostatitis.
• C. Short-course cystitis regimen; inadequate for prostatic tissue penetration or duration.
• D. Inadequate duration and poor prostatic tissue penetration for prostatitis.
• E. Short-course cystitis regimen; inadequate for prostatic tissue penetration or duration.

This patient has Eron class II cellulitis: localised infection with a comorbidity (diabetes) that may complicate or delay resolution, but no signs of systemic toxicity or decompensation. NICE guidance recommends that patients with Eron class I or II cellulitis who are systemically well can usually be managed with oral antibiotics in the community or via an ambulatory care pathway, with flucloxacillin as first-line for non-penicillin-allergic patients. Admission and intravenous antibiotics are reserved for Eron class III (systemic illness or significant comorbidity instability) or class IV (sepsis or life-threatening infection) presentations. Close follow-up within 48 hours ensures early detection of treatment failure or progression.

• A. There is no indication for intravenous antibiotics or vascular surgery input in this uncomplicated presentation.
• B. There is no evidence of necrotising infection to warrant meropenem or emergency debridement.
• C. Intravenous therapy and admission are not required as the patient is systemically well with localised disease.
• D. Clarithromycin is not first-line for cellulitis and macrolide monotherapy does not reflect the correct antibiotic choice.

This patient has classic features of necrotising fasciitis: pain disproportionate to clinical signs, skin anaesthesia, crepitus, rapidly progressive discolouration and systemic sepsis. This is a surgical emergency, and the single most important intervention is urgent surgical exploration and debridement of necrotic tissue, performed in parallel with aggressive resuscitation and broad-spectrum intravenous antibiotics. Imaging or biopsy should never delay definitive surgical management, as mortality rises significantly with every hour of delay. Early senior surgical and microbiology involvement is essential.

• A. Imaging must not delay surgery; the diagnosis is clinical and time to theatre is critical.
• C. Conservative measures are inappropriate and dangerous given the signs of a necrotising soft tissue infection.
• D. Biopsy delays definitive treatment and is not required to confirm a clinical diagnosis of necrotising fasciitis.
• E. Antibiotics alone are inadequate; source control with debridement is essential and delay increases mortality.

MRI is the investigation of choice for suspected osteomyelitis in children, as it has high sensitivity for detecting early marrow oedema, abscess formation and subperiosteal collections before changes are visible on plain radiographs. Plain films are frequently normal in the first 1–2 weeks of infection, so a normal radiograph does not exclude osteomyelitis. Staphylococcus aureus is the most common causative organism in paediatric osteomyelitis across all age groups. Blood cultures and inflammatory markers support the diagnosis but do not replace imaging to define the extent of bone and soft tissue involvement.

• A. Imaging is required to confirm the diagnosis and define extent of disease; blood cultures alone are insufficient.
• B. Bone scintigraphy is less specific than MRI and is usually reserved for cases where MRI is unavailable or contraindicated.
• C. Ultrasound can detect effusions or subperiosteal collections but lacks the sensitivity of MRI for marrow involvement.
• E. CT involves ionising radiation and is less sensitive than MRI for early bone marrow changes in children.

Diabetic foot infections are frequently polymicrobial, involving Gram-positive cocci, Gram-negative bacilli and anaerobes, particularly in chronic or deep ulcers, so empirical broad-spectrum antibiotic cover is required pending culture results. The ability to probe to bone through an ulcer is a strong clinical predictor of underlying osteomyelitis, and further imaging (such as plain radiograph followed by MRI if needed) should be arranged to assess bone involvement. Multidisciplinary diabetic foot team input, including vascular and orthopaedic specialists, is essential for ongoing management. Delaying appropriate antibiotic therapy or imaging risks progression to limb-threatening infection.

• A. Amputation is not first-line and is reserved for cases with extensive necrosis or failed medical management.
• C. A 6-week delay risks progression of infection and possible limb-threatening complications.
• D. Flucloxacillin alone does not provide adequate cover for the polymicrobial nature of diabetic foot infections.
• E. Dressings alone are inadequate when there is clinical evidence of infection and possible osteomyelitis.

Oral vancomycin is now first-line treatment for a first episode of Clostridioides difficile infection, as it achieves high luminal concentrations in the colon with minimal systemic absorption, directly targeting the site of infection. Fidaxomicin is an alternative first-line option, particularly in patients at high risk of recurrence. Oral metronidazole is reserved for use when vancomycin or fidaxomicin are unavailable. Intravenous vancomycin does not achieve adequate concentrations in the bowel lumen and is not effective for treating C. difficile colitis, as the drug works locally rather than systemically.

• A. Intravenous metronidazole is not used for C. difficile colitis as oral therapy is required to act locally in the gut.
• B. Linezolid has no established role in the treatment of C. difficile infection.
• C. Metronidazole is no longer first-line and is reserved for situations where vancomycin or fidaxomicin cannot be used.
• D. Intravenous vancomycin does not reach adequate concentrations in the bowel lumen to treat C. difficile colitis.

Stool culture is indicated in this patient because he works in a care setting handling food or providing care to vulnerable people, which creates a public health risk of onward transmission, and recent travel raises the possibility of a notifiable or less common pathogen. Even though he is systemically well and would not routinely need investigation, occupational risk changes management to identify the causative organism and guide public health advice about return to work. Antibiotics are not indicated empirically in otherwise well patients with acute infective diarrhoea, as most cases are self-limiting and antibiotics can prolong carriage or precipitate complications such as haemolytic uraemic syndrome with certain pathogens.

• A. Admission is unnecessary as he is systemically well with no signs of dehydration.
• C. Metronidazole is not indicated empirically and is not first-line for undifferentiated infective diarrhoea.
• D. Empirical antibiotics are not indicated before an organism is identified in a systemically well patient.
• E. No stool testing would miss identifying a pathogen relevant to his occupational risk and public health reporting.

This patient has the classic Charcot's triad of fever, jaundice, and right upper quadrant pain, which strongly suggests acute cholangitis caused by obstruction and infection of the biliary tree, usually secondary to choledocholithiasis. The combination of a cholestatic liver picture (raised ALP and bilirubin) with systemic sepsis supports biliary infection rather than isolated obstruction. Management requires urgent intravenous antibiotics and biliary decompression, typically via ERCP, once the patient is stabilised. Untreated cholangitis can progress to septic shock and is a medical emergency.

• B. Acute cholecystitis typically causes right upper quadrant pain and fever but not jaundice, as the common bile duct is not obstructed.
• C. Choledocholithiasis alone would cause jaundice and pain but not the fever and systemic inflammatory response seen here.
• D. Viral hepatitis causes a hepatocellular pattern with markedly raised transaminases rather than a predominantly cholestatic picture with fever and right upper quadrant pain.
• E. Acute pancreatitis presents with epigastric pain radiating to the back and a markedly raised amylase or lipase, not a cholestatic jaundice picture with fever.

Persistence of hepatitis B surface antigen (HBsAg) for more than six months defines chronic infection, and the presence of IgG core antibody confirms that this is an established rather than acute infection. Positive hepatitis B e antigen (HBeAg) indicates active viral replication and high infectivity, as e antigen is a marker of ongoing viral protein production. Surface antibody (anti-HBs) negativity confirms the patient has not cleared the virus or developed immunity. This pattern warrants referral to hepatology for consideration of antiviral therapy and monitoring for progression to cirrhosis.

• A. Resolved infection would show surface antigen negative, surface antibody positive, and core antibody positive, not surface antigen positive.
• C. The window period refers to the acute phase when surface antigen has become negative but surface antibody has not yet appeared, with core antibody IgM positive; this patient has IgG core antibody and persistent surface antigen.
• D. Vaccination produces an isolated positive surface antibody with negative core antibody, which does not match this pattern.
• E. Low infectivity chronic infection is typically e antigen negative with e antibody positive, not e antigen positive.

In a vaccinated healthcare worker with unknown antibody response exposed to a hepatitis B surface antigen-positive source, the first step is to urgently check the surface antibody (anti-HBs) titre to determine if they are a known responder. If the level is adequate (typically above 10 mIU/mL), no further action is usually needed beyond a booster dose; if the response is inadequate or unknown and cannot be checked quickly, hepatitis B immunoglobulin alongside a vaccine booster may be indicated depending on occupational health protocols. Management is guided by UK Health Security Agency and occupational health guidance, balancing the need for rapid risk assessment with appropriate prophylaxis. This stepwise approach avoids unnecessary immunoglobulin administration in those already immune.

• A. Antiretroviral post-exposure prophylaxis is used for HIV exposure, not hepatitis B.
• B. Immunoglobulin should not be given reflexively without first assessing the doctor's antibody status, as it may be unnecessary in a confirmed responder.
• C. Giving a booster without first checking antibody status does not confirm whether the doctor is protected and may be inappropriate if immunoglobulin is also needed.
• D. Vaccination does not guarantee an adequate antibody response in all individuals, so antibody status must be checked rather than assuming protection.

A positive hepatitis C antibody test indicates past or current exposure but does not distinguish between cleared infection and ongoing active infection, so hepatitis C RNA testing by polymerase chain reaction (PCR) is required to confirm current viraemia. If RNA is detected, the patient has chronic infection and should be referred for genotyping and treatment with direct-acting antivirals, which now achieve sustained virological response rates above 95% with short courses of 8 to 12 weeks. Liver biopsy and interferon-based regimens have largely been superseded by non-invasive fibrosis assessment and all-oral direct-acting antiviral therapy. Normal liver function tests do not exclude chronic hepatitis C infection.

• A. Repeat antibody testing is unnecessary once antibody positivity is established; RNA testing is needed to determine current infection status.
• C. Interferon-based regimens have been replaced by direct-acting antivirals as first-line therapy due to better efficacy and tolerability.
• D. Liver biopsy is invasive and no longer required for diagnosis; non-invasive methods such as transient elastography are preferred, and RNA testing confirms infection first.
• E. Transplantation assessment is reserved for decompensated cirrhosis or hepatocellular carcinoma, not for initial diagnosis of an asymptomatic patient.

Spontaneous bacterial peritonitis (SBP) is diagnosed when the ascitic fluid polymorphonuclear neutrophil count exceeds 250 cells/microlitre, reflecting an infective inflammatory response within the peritoneal fluid of a cirrhotic patient. This threshold is used regardless of whether ascitic fluid culture grows an organism, since culture can be falsely negative in up to 40% of true SBP cases. Empirical antibiotics, typically intravenous cefotaxime or piperacillin-tazobactam per local protocols, should be started promptly once this neutrophil threshold is met, without waiting for culture results. A raised serum-ascites albumin gradient indicates portal hypertension as the cause of ascites but does not diagnose infection.

• A. Ascitic protein level helps assess the risk of SBP and guide prophylaxis decisions but is not itself diagnostic of active infection.
• B. The serum-ascites albumin gradient distinguishes portal hypertensive from non-portal hypertensive causes of ascites, not infection.
• D. Raised ascitic amylase suggests pancreatic ascites or bowel perforation rather than spontaneous bacterial peritonitis.
• E. Low ascitic glucose is more suggestive of secondary bacterial peritonitis from a perforated viscus, not the primary diagnostic criterion for SBP.

In neonates and infants under three months with suspected bacterial meningitis, empirical therapy should combine cefotaxime with amoxicillin (or ampicillin) to cover group B Streptococcus, Escherichia coli, and Listeria monocytogenes, the latter of which is not reliably covered by cephalosporins alone. Cefotaxime is preferred over ceftriaxone in neonates because ceftriaxone can displace bilirubin from albumin and increase the risk of kernicterus, and it is also associated with biliary sludging in young infants. Amoxicillin provides specific cover against Listeria, which is a particular concern in neonates, the elderly, and immunocompromised patients. This combination reflects UK guidance for age-specific empirical meningitis treatment.

• A. Cefotaxime alone does not adequately cover Listeria monocytogenes, which is an important pathogen in this age group.
• B. Ceftriaxone is avoided in neonates due to the risk of bilirubin displacement and kernicterus, and it also does not cover Listeria.
• C. Vancomycin plus ceftriaxone is used for penicillin-resistant pneumococcus concerns in other settings, not as first-line neonatal empirical therapy, and ceftriaxone is unsuitable in neonates.
• E. Benzylpenicillin alone does not provide adequate cover against gram-negative organisms such as Escherichia coli, which are common in neonatal meningitis.

This presentation with fever, meningism, and a non-blanching purpuric rash is highly suggestive of meningococcal disease, and UK guidance recommends giving benzylpenicillin (intramuscular or intravenous) in the pre-hospital setting without delay, as every minute counts in reducing mortality from meningococcal sepsis. This should be done before transfer to hospital unless it would cause a significant delay in transfer, and should not be withheld due to penicillin allergy concerns unless there is a clear history of anaphylaxis. Waiting for hospital arrival risks rapid deterioration into septic shock. Lumbar puncture and oral prophylactic antibiotics are not appropriate or safe actions in this acute pre-hospital setting.

• A. Dexamethasone is an adjunct used in hospital for bacterial meningitis in certain circumstances, not a substitute for urgent antibiotics in the pre-hospital setting.
• B. Delaying antibiotics until hospital arrival risks rapid clinical deterioration from meningococcal sepsis, which can progress within hours.
• C. Ciprofloxacin is used for contact prophylaxis of close contacts, not for treating the acutely unwell patient themselves.
• D. Lumbar puncture is not performed in the community and would be contraindicated given the risk of rapidly progressive sepsis and raised intracranial pressure.

Focal neurological signs, a depressed or fluctuating level of consciousness, and asymmetric or abnormal pupillary responses are all indicators of potentially raised intracranial pressure or an intracranial mass lesion, which are contraindications to lumbar puncture until imaging has excluded a risk of brain herniation. A CT scan of the head should be performed before lumbar puncture in such cases to assess for mass effect, hydrocephalus, or midline shift. Importantly, antibiotics should never be delayed while awaiting CT or lumbar puncture, as prompt treatment of suspected bacterial meningitis takes priority over diagnostic confirmation. If CT is unremarkable, lumbar puncture can then be performed safely.

• A. A neurological examination alone is insufficient to exclude a mass lesion or raised intracranial pressure; imaging is required.
• C. Mannitol is not indicated without evidence of raised intracranial pressure on imaging and would not be given empirically before assessment.
• D. Lumbar puncture in the presence of focal neurological signs and an abnormal pupil carries a risk of precipitating brain herniation and is contraindicated until imaging is performed.
• E. Antibiotics and urgent assessment should not be delayed for a neurosurgical opinion, and CT head is the appropriate immediate step rather than specialist referral first.

A markedly raised neutrophil-predominant white cell count, high protein, and a CSF:plasma glucose ratio below 0.4 (here roughly 0.23) are classic for bacterial meningitis. Viral meningitis typically shows a lymphocytic pleocytosis with normal or mildly raised protein and normal glucose. TB meningitis causes a lymphocytic picture with very high protein and a more gradual, less dramatic glucose fall. The purpuric rash and rapid onset further support a bacterial (likely meningococcal) cause.

• A. Viral meningitis shows lymphocytic, not neutrophilic, pleocytosis with normal glucose.
• B. Fungal meningitis usually causes a lymphocytic pleocytosis and occurs in immunocompromised patients.
• C. Subarachnoid haemorrhage causes uniformly bloody CSF or xanthochromia, not a neutrophil-predominant pleocytosis with low glucose.
• E. TB meningitis typically has a lymphocytic picture and a more subacute course over days to weeks.

Fever, altered behaviour, focal seizures and temporal lobe changes on imaging strongly suggest herpes simplex encephalitis, which carries high mortality and morbidity if treatment is delayed. UK and international guidelines recommend starting intravenous aciclovir empirically as soon as the diagnosis is suspected, without waiting for CSF PCR confirmation, as PCR results may take time and delay worsens outcomes. Lumbar puncture should still be performed to send CSF for HSV PCR, but this should not delay starting treatment. Imaging can support the diagnosis but should not postpone empirical therapy.

• B. Oral valaciclovir does not achieve adequate CNS levels; intravenous aciclovir is required and should start immediately, not after a delay.
• C. Treatment should be started empirically; waiting for PCR confirmation risks a delay that worsens neurological outcome.
• D. MRI can be arranged but should not delay empirical aciclovir therapy.
• E. Ceftriaxone treats bacterial meningitis, not the viral encephalitis suggested by this presentation.

A glandular-fever-like illness with fever, pharyngitis, lymphadenopathy, maculopapular rash and oral ulcers occurring 2-4 weeks after a high-risk sexual exposure is highly suggestive of HIV seroconversion illness. A negative monospot test makes Epstein-Barr virus infectious mononucleosis less likely. Diagnosis requires a combined HIV antigen/antibody (fourth-generation) test, which may still be negative very early in seroconversion, so a repeat test at 4 weeks is advised if initially negative with ongoing clinical suspicion. Early recognition is important as this period carries high infectivity.

• A. CMV infection can cause a similar mononucleosis-like illness but is less likely given the specific recent high-risk sexual exposure history.
• C. A negative monospot test and the recent high-risk sexual exposure make EBV infectious mononucleosis less likely than HIV seroconversion.
• D. Streptococcal pharyngitis does not typically cause a widespread rash, oral ulcers or occur specifically after sexual exposure.
• E. Secondary syphilis typically presents with a rash involving the palms and soles and occurs later, several weeks to months after primary infection, without this acute febrile pharyngitic picture.

Post-exposure prophylaxis (PEP) should be started as soon as possible after a significant occupational or sexual exposure to HIV, ideally within hours and no later than 72 hours, as efficacy declines with time. A baseline HIV test is taken but treatment should not wait for the result, since the source is known to be HIV-positive with a high viral load, placing this injury at significant risk. PEP typically consists of a combination antiretroviral regimen (such as tenofovir/emtricitabine plus raltegravir) continued for 28 days, with follow-up HIV testing arranged.

• A. A hollow-bore needlestick from a high viral load source carries significant transmission risk and warrants prompt action.
• B. Treatment should not be delayed awaiting the baseline test result given the known high-risk source and the time-critical nature of PEP.
• C. PEP efficacy depends on early initiation, ideally within hours; waiting 72 hours would make it far less effective.
• E. Immunoglobulin has no role in HIV post-exposure prophylaxis.

Pre-exposure prophylaxis (PrEP) with tenofovir disoproxil/emtricitabine is recommended for HIV-negative individuals at substantial ongoing risk of HIV acquisition, including men who have sex with men with inconsistent condom use and a recent bacterial sexually transmitted infection, both of which are recognised risk markers. Before starting, renal function and HIV status must be confirmed negative, as here. PrEP is taken either daily or as event-based dosing around sexual activity, with regular HIV testing and renal monitoring during use.

• A. There is no licensed vaccination against HIV.
• B. He has tested HIV-negative, so full antiretroviral therapy for established infection is not appropriate.
• D. His risk profile meets established criteria for PrEP, so medication should be offered rather than condoms alone.
• E. PEP is used after a specific high-risk exposure has occurred, not as ongoing protection for continued risk; PrEP is appropriate here.

A low CD4 count below 200 cells/microlitre, progressive breathlessness with a disproportionately clear chest examination, exertional desaturation and bilateral interstitial infiltrates on chest X-ray are classic for Pneumocystis jirovecii pneumonia. First-line treatment is high-dose co-trimoxazole (trimethoprim-sulfamethoxazole), with adjunctive corticosteroids added if the patient is significantly hypoxaemic, as here. Diagnosis can be supported by bronchoalveolar lavage with silver staining or PCR, but treatment should not be delayed in a clinically convincing picture in an at-risk patient.

• A. This four-drug regimen treats tuberculosis, which would more typically show focal consolidation, cavitation or effusion rather than diffuse bilateral interstitial infiltrates.
• B. Fluconazole treats fungal infections such as candidiasis or cryptococcosis, not Pneumocystis pneumonia.
• C. Clarithromycin is used for atypical bacterial pneumonia or Mycobacterium avium complex, not first-line for Pneumocystis jirovecii pneumonia.
• D. Amoxicillin treats typical bacterial pneumonia, which does not fit this subacute presentation with a clear chest on examination and interstitial changes.

Patients with HIV and a CD4 count below 200 cells/microlitre are at significant risk of Pneumocystis jirovecii pneumonia (PCP) and should receive primary prophylaxis. Co-trimoxazole (trimethoprim-sulfamethoxazole) is the first-line agent for PCP prophylaxis. Prophylaxis is continued until the CD4 count rises above 200 cells/microlitre for at least three months on antiretroviral therapy. Mycobacterium avium complex prophylaxis with azithromycin is only indicated once CD4 falls below 50 cells/microlitre, which is not the case here.

• B. Valaciclovir is not indicated as routine prophylaxis based on CD4 count.
• C. Fluconazole is not used as routine primary prophylaxis against fungal infection in HIV at this CD4 level.
• D. Azithromycin is used for Mycobacterium avium complex prophylaxis, indicated only when CD4 is below 50 cells/microlitre.
• E. Isoniazid prophylaxis is reserved for latent tuberculosis infection, not given routinely by CD4 count alone.

All pregnant women with HIV should start combination antiretroviral therapy as soon as possible after diagnosis or confirmation of pregnancy, regardless of CD4 count or viral load, to achieve maximal viral suppression before delivery and minimise the risk of mother-to-child transmission. The goal is an undetectable viral load by the time of delivery, which determines the mode of delivery and need for intrapartum intervention. Early initiation gives the longest time to achieve viral suppression. Delaying treatment increases the risk of a detectable viral load at term and the need for additional interventions such as intravenous zidovudine infusion or caesarean section.

• A. Delaying treatment increases the risk of transmission; therapy should begin as soon as possible, not deferred to later pregnancy.
• B. Mode of delivery depends on viral load near term; vaginal delivery is appropriate if viral load is suppressed.
• D. Antiretroviral therapy should not be withheld, as early viral suppression reduces transmission risk.
• E. Treatment is started irrespective of viral load threshold, not reserved for high viral loads only.

Nucleic acid amplification testing (NAAT) is the investigation of choice for chlamydia, with high sensitivity and specificity even in asymptomatic individuals. In women, a self-taken vulvovaginal swab is as sensitive as an endocervical swab and is preferred because it avoids the need for speculum examination. Chlamydia trachomatis is frequently asymptomatic, particularly in women, so screening relies on NAAT rather than clinical findings. Culture and Gram stain are not sensitive enough to detect this intracellular organism reliably.

• A. Serology is not useful for diagnosing active genital chlamydia infection due to poor sensitivity and specificity.
• B. Standard culture is not reliable for chlamydia, an obligate intracellular organism that grows poorly outside cells.
• D. Urine dipstick does not detect chlamydia and is used to screen for urinary tract infection.
• E. Gram stain lacks sensitivity for chlamydia and is not the recommended diagnostic method.

Doxycycline 100 mg twice daily for 7 days is first-line treatment for uncomplicated genital chlamydia infection in non-pregnant adults, with cure rates exceeding those of azithromycin in recent trials, particularly for rectal infection. Azithromycin as a single dose is now reserved for cases where doxycycline is contraindicated or adherence is a concern, such as in pregnancy. Doxycycline should be avoided in pregnant or breastfeeding women due to effects on fetal bone and teeth development, in whom azithromycin is used instead.

• A. Erythromycin is reserved for pregnant women who cannot take doxycycline, not first-line in non-pregnant adults.
• B. Metronidazole is used for trichomoniasis and bacterial vaginosis, not chlamydia.
• D. Azithromycin is now second-line for uncomplicated chlamydia due to lower efficacy against rectal infection compared with doxycycline.
• E. Ceftriaxone is the treatment for gonorrhoea, not chlamydia.

Pelvic inflammatory disease is diagnosed clinically based on history and examination findings such as lower abdominal pain, cervical excitation and adnexal tenderness, and empirical antibiotic treatment should be started promptly without waiting for swab results, since delayed treatment increases the risk of long-term complications such as tubal infertility and ectopic pregnancy. BASHH recommends empirical triple therapy covering Chlamydia trachomatis, Neisseria gonorrhoeae and anaerobic organisms: a single dose of intramuscular ceftriaxone, plus oral doxycycline and oral metronidazole for 14 days. Swabs should still be taken to guide further management but should not delay treatment initiation.

• A. Ultrasound is not required to make the clinical diagnosis and should not delay treatment.
• B. Doxycycline alone does not provide adequate cover against gonorrhoea or anaerobic organisms.
• C. Metronidazole alone does not cover chlamydia or gonorrhoea, the main causative organisms.
• E. Treatment should not be delayed pending microbiology results, as this increases the risk of complications.

The painless, indurated ulcer (chancre) with non-tender regional lymphadenopathy is characteristic of primary syphilis caused by Treponema pallidum. Direct detection by dark-field microscopy or PCR of exudate from the ulcer base is the most sensitive method in the earliest stage, as serological tests may still be negative in the first few weeks of infection before antibody responses develop. Serology (treponemal EIA screening followed by confirmatory tests, with RPR used to monitor disease activity and treatment response) should still be performed but can give a false-negative result very early in primary syphilis. Herpes simplex typically causes multiple painful vesicular or ulcerative lesions rather than a single painless chancre.

• A. Haemophilus ducreyi causes chancroid, which produces painful, ragged ulcers rather than a painless indurated chancre.
• B. RPR alone can also be negative early in infection and is used for monitoring rather than initial diagnosis.
• C. Treponemal EIA may be falsely negative in very early primary syphilis before seroconversion occurs.
• D. The painless, indurated character of the lesion is not typical of herpes simplex, which causes painful vesicular ulcers.

The Jarisch-Herxheimer reaction is a self-limiting febrile illness with myalgia, headache and malaise occurring within the first 24 hours after starting antitreponemal treatment, caused by the release of lipopolysaccharide-like toxins from dying spirochaetes. It is not an allergic reaction and does not involve urticaria, wheeze or angioedema, which would suggest true anaphylaxis instead. It is managed supportively with antipyretics such as paracetamol, and patients should be reassured that this does not represent treatment failure or penicillin allergy. Treponema pallidum has no documented resistance to penicillin, which remains highly effective treatment.

• A. The timing and systemic features are typical of a Herxheimer reaction rather than localised superinfection.
• B. There is no documented penicillin resistance in Treponema pallidum; penicillin remains universally effective.
• C. Serum sickness develops days after exposure with rash and arthralgia, not within hours of treatment.
• D. Anaphylaxis would present with urticaria, wheeze, angioedema or hypotension, none of which are present here.

A first episode of genital herpes is treated with oral aciclovir (or valaciclovir/famciclovir) started within 5 days of onset, or later if new lesions are still forming, to reduce duration and severity of symptoms. Supportive measures such as saline bathing and topical lidocaine can be added for symptomatic relief but do not replace antivirals. IV therapy is reserved for severe disease, urinary retention, or immunocompromise. Patients should be counselled that recurrences are usually milder and shorter, and suppressive therapy is only considered for frequent recurrences (typically ≥6 per year).

• A. IV aciclovir is reserved for severe, disseminated disease or when oral intake/urination is not possible.
• B. Long-term suppressive valaciclovir is used for frequent recurrences, not for a first episode.
• C. Topical lidocaine helps pain but does not treat the underlying viral infection or reduce duration of the episode.
• D. Untreated primary herpes causes prolonged, more severe symptoms; antiviral treatment is indicated at presentation.

Genital warts are caused by human papillomavirus, predominantly types 6 and 11, which are low-risk oncogenic types but highly associated with anogenital warts. The UK HPV vaccination programme (quadrivalent or nonavalent vaccine) covers types 6 and 11 in addition to the high-risk oncogenic types 16 and 18, so vaccination reduces both warts and cervical cancer risk. It is offered routinely to adolescents before likely sexual debut, but catch-up and gender-neutral programmes exist. Vaccination does not treat existing infection but reduces future acquisition and transmission.

• A. Cervical smears screen for cervical dysplasia caused by high-risk HPV but do not prevent transmission of the virus.
• B. Aciclovir is active against herpes simplex virus, not HPV, and does not prevent wart transmission.
• C. Benzathine penicillin treats syphilis, a bacterial infection, and has no role against HPV.
• D. Hepatitis B vaccine protects only against hepatitis B virus and has no cross-protection against HPV.

In a pregnant woman with significant chickenpox exposure and uncertain or no history of previous varicella infection, varicella zoster IgG status should be checked urgently; if she is non-immune (IgG negative), varicella zoster immunoglobulin (VZIG) should be given as soon as possible, ideally within 10 days of exposure, to reduce the risk of maternal and fetal complications. If she is already immune, no further action is needed. The live varicella vaccine is contraindicated in pregnancy. Oral aciclovir is used if she develops the rash, not as pre-exposure prophylaxis in a seronegative contact.

• A. Aciclovir prophylaxis before confirmed infection is not the recommended approach; VZIG is used for non-immune exposed contacts.
• B. The varicella vaccine is a live vaccine and is contraindicated during pregnancy.
• D. Trimester alone does not determine risk; immunity status must be established, as exposure can still cause fetal varicella syndrome or severe maternal infection.
• E. VZIG should not be given blindly; testing for IgG status first avoids unnecessary treatment in women who are already immune.

After a needlestick injury, the wound should be washed immediately under running water with soap, allowing it to bleed gently rather than being squeezed or sucked, and then covered with a waterproof dressing. The incident must be reported promptly to occupational health or the relevant local service for risk assessment, which determines the need for further testing or post-exposure prophylaxis based on the source patient's bloodborne virus status. Hepatitis C has no licensed post-exposure prophylaxis, so management focuses on baseline and follow-up testing to detect seroconversion and allow early treatment if needed. Squeezing the wound or using antiseptics with occlusive closure is not recommended as it may increase local tissue trauma or does not add benefit.

• A. Suturing a needlestick wound is unnecessary and inappropriate; the wound should be left open and simply dressed.
• B. There is no licensed post-exposure prophylaxis for hepatitis C; antiretroviral PEP is relevant to HIV exposure after risk assessment, not given empirically.
• C. Vigorous squeezing can cause additional tissue trauma and does not reduce infection risk; gentle encouragement of bleeding is sufficient.
• D. A tourniquet is not indicated and could worsen local injury without reducing viral transmission risk.

Under the Health Protection (Notification) Regulations 2010, it is the legal duty of the registered medical practitioner who attends a patient suspected of having a notifiable disease, such as measles, to notify the local authority or UKHSA health protection team, usually within 3 days (or urgently by telephone for serious cases). Notification should occur on clinical suspicion alone and should not be delayed pending laboratory confirmation. This duty exists to enable rapid public health action such as contact tracing and outbreak control, and is separate from, though complemented by, laboratory reporting duties for diagnostic laboratories.

• A. Laboratories have a duty to report certain causative agents, but the statutory notification duty for the clinical case lies with the attending doctor.
• C. Family members have no legal obligation or role in notifying public health authorities.
• D. Patients have no legal duty to notify public health authorities of their own diagnosis.
• E. Hospital executives have no individual statutory notification duty for notifiable diseases.

In any febrile traveller returning from a malaria-endemic area, thick and thin blood films are the gold-standard investigation: the thick film is used to detect and quantify parasitaemia, while the thin film identifies the Plasmodium species based on morphology, which guides treatment choice and severity assessment. Rapid diagnostic antigen tests can supplement but not replace microscopy, and films should be repeated if initially negative but clinical suspicion remains high. Blood cultures are useful to exclude bacterial sepsis but do not diagnose malaria. Antibody serology reflects past rather than current infection and is not used for acute diagnosis.

• B. Chest X-ray is not part of the standard diagnostic work-up for malaria unless pulmonary complications are suspected.
• C. Eosinophilia is more suggestive of helminth infection and is not a reliable marker for malaria.
• D. Antibody titres indicate past exposure and are not useful for diagnosing acute malaria infection.
• E. Blood cultures help identify bacterial causes of fever but do not detect malaria parasites.