Bacterial food poisoning (BFP)
Bacterial food poisoning (BFP) represents a polyetiological group of acute intestinal infections (AII). Their main culprits are various opportunistic bacteria. In clinical practice, these conditions are combined into a single nosological form because they share common features in epidemiology, mechanisms of development (pathogenesis), routes of infection, and require similar approaches to prevention and therapeutic tactics.
The fundamental difference between BFP and other acute intestinal infections lies in the mechanism of disease onset: symptoms occur after consuming food in which bacterial enterotoxins have already accumulated. These very toxins cause a very short incubation period and the rapid development of signs of gastritis and/or enteritis. The disease is accompanied by a pronounced intoxication syndrome, but has a short-term and, as a rule, self-limiting course.
Etiology and pathogenesis of sepsis
Sepsis is also a polyetiological disease. Its typical pathogens are pyogenic and anaerobic opportunistic microflora that normally inhabit human skin and mucous membranes (aerobic automicroflora). Most of these microorganisms are aerobes and extracellular parasites.
The most important feature of sepsis pathogens is the complete absence of organ or tissue tropism. This means that bacteria are capable of affecting absolutely any organs. Local inflammation in sepsis is almost always purulent or purulent-hemorrhagic in character. Necrosis and tissue destruction processes predominate in the foci, whereas cellular proliferation reactions and infiltration are extremely weakly expressed.
The role of gram-positive and gram-negative flora
Gram-negative microflora dominates the structure of sepsis pathogens (accounting for 60–70% of cases), while gram-positive flora causes about 30–40% of episodes. Although the specific microbe species does not radically change the outcome and general clinical picture, it determines important pathogenetic nuances.
| Characteristic | Gram-positive flora | Gram-negative flora |
|---|---|---|
| Main representatives | Staphylococcus, Streptococcus, Pneumococcus, listeria | E. coli, Pseudomonas aeruginosa, Proteus, Klebsiella, gonococcus, meningococcus, salmonella |
| Virulence factors | Release protein exotoxins | Contain endotoxin (lipopolysaccharide — LPS) |
| Clinical features | Metastatic purulent foci are more frequently formed | Intoxication syndrome is significantly more pronounced |
| Risk of shock development | Relatively rare (exception — Staphylococcus aureus, which releases enterotoxin) | Infectious-toxic shock develops 4–5 times more frequently |
Specific forms and risk factors of sepsis
In modern medicine, there is an alarming trend: an increase in the frequency of hospital-acquired sepsis in patients in intensive care units (ICUs). The main role here is played by non-fermenting gram-negative bacteria: Pseudomonas aeruginosa, Acinetobacter spp., Klebsiella pneumoniae, Enterobacter cloacae. Key risk factors in the ICU are prolonged mechanical ventilation (MV) and massive antibiotic therapy (especially third-generation cephalosporins and gentamicin).
In patients with severe underlying pathologies (terminal conditions, HIV infection, radiation or burn disease), sepsis can be caused even by saprophytes (bacteroides, coagulase-negative staphylococci, non-hemolytic streptococci), as well as pathogenic fungi (Candida, aspergilli), actinomycetes, viruses, and parasites.
In obstetric practice, triggers of sepsis often include:
- chronic foci of infection and immunodeficiency states;
- community-acquired infected abortions and intrauterine manipulations;
- Cesarean section and premature birth;
- premature rupture of membranes;
- blood loss and hemorrhagic shock.
To avoid confusing the features of flora in sepsis, remember: Gram(–) bacteria contain endotoxin (LPS) and cause shock 4–5 times more often. Gram(+) bacteria release exotoxins and more frequently form purulent foci.
Class and exam questions
How does bacterial food poisoning differ from other intestinal infections?
BFP arises from consuming food with already accumulated bacterial enterotoxins. It is characterized by a short incubation period, signs of gastritis or enteritis, and a rapid self-limiting course.
Which microorganisms most commonly cause sepsis?
In 60–70% of cases, these are gram-negative bacteria (E. coli, Pseudomonas aeruginosa, Proteus), and in 30–40% — gram-positive (Staphylococcus, Streptococcus). These are mainly opportunistic automicroflora of the skin and mucous membranes.
Why does gram-negative sepsis more frequently lead to shock?
Gram-negative bacteria contain endotoxin — lipopolysaccharide (LPS). With its massive release, intoxication is significantly more pronounced, which increases the risk of developing infectious-toxic shock by 4–5 times.
What triggers the development of hospital-acquired sepsis in the ICU?
The main risk factors are prolonged mechanical ventilation and widespread use of antibiotics (third-generation cephalosporins and gentamicin). This contributes to the growth of non-fermenting gram-negative bacteria, such as Pseudomonas aeruginosa and Klebsiella.
What else to study on this topic
- Pathogenesis of infectious-toxic shock development in staphylococcal infection.
- Mechanisms of action of bacterial enterotoxins on the gastrointestinal mucosa.
- The role of saprophytic flora in the development of sepsis in patients with severe immunodeficiencies.
- Features of morphological changes in organs during purulent-hemorrhagic inflammation.
- The effect of prolonged mechanical ventilation on the colonization of the respiratory tract by non-fermenting bacteria.
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