Epidemiology and routes of transmission
The source of infection is traditionally infected animals, most commonly cattle and sheep. The disease is transmitted through several routes depending on the conditions of contact with infected material:
- Contact route — the most frequent scenario for the development of surgical forms. Infection occurs during the processing of skin or fur, carcass butchering, and direct interaction with a sick or dead animal. Spores penetrate through microtraumas of the skin, abrasions, or cuts.
- Alimentary route — occurs when consuming meat from an infected animal.
- Airborne-dust (aerogenic) route — associated with the inhalation of spores, for example, during work with hides in production.
- Vector-borne route — transmission of infection through insect bites (in particular, flies), which is not ruled out in epidemic foci.
Clinical forms of the disease
Depending on the portal of entry, three main forms of anthrax are distinguished. Intestinal and pulmonary forms occur with alimentary and aerogenic infection, respectively. They are characterized by an extremely severe course, unfavorable prognosis, and require hospitalization exclusively in infectious disease departments.
For the surgeon, the cutaneous form is of key importance. It accounts for the bulk of cases that a doctor may encounter during an initial examination. In 60% of cases, open areas of the face, head, and neck are affected, and in 25% — the hands. The mortality rate for the cutaneous form ranges from 2 to 20%.
Development of the anthrax carbuncle
Following the incubation period (2–7 days), a specific carbuncle begins to form at the site of spore inoculation. This process goes through several consecutive stages:
- Appearance of a small red nodule.
- Within 1–2 days, the nodule transforms into a vesicle with characteristic bluish-pink contents.
- After the vesicle opens, a hard, thick black eschar forms in its place.
- Around the eschar, satellite lesions appear — new small vesicles.
Locally, the process is accompanied by rapidly developing edema of the surrounding tissues, regional lymphadenitis, and profuse discharge of serous or bloody fluid from under the eschar. The general condition of the patient depends on the form: in localized cases, it is barely affected, but when the process generalizes (sepsis develops), it becomes extremely severe, accompanied by pronounced intoxication and high fever. The outcome of the local process is the rejection of the eschar and the formation of one or more ulcers with insignificant purulent discharge.
Diagnostics and treatment
Establishing a diagnosis requires evaluating the clinical picture and mandatory bacteriological confirmation. The discharge from the vesicle, ulcer, or the eschar itself is used for seeding. Differential diagnosis of the cutaneous form must be carried out with a mundane staphylococcal carbuncle, furuncle, and the bubonic form of plague.
The most important rule of surgical tactics: any active manipulations (incision, excision of the lesion, removal of the eschar) are categorically unacceptable, as they lead to the generalization of the infection and the development of sepsis.
The conservative management regimen includes:
- Ensuring complete rest for the patient.
- Applying an aseptic dressing to the carbuncle area.
- Administration of antianthrax serum (50–150 ml at intervals of 2–3 days).
- Prescription of broad-spectrum antibiotics (benzylpenicillin, ciprofloxacin, erythromycin) and chemotherapeutic agents.
Briefly: answers to topical questions
How does the clinical picture of an anthrax carbuncle differ from a mundane staphylococcal carbuncle?
The clinical picture of an anthrax carbuncle differs from a mundane staphylococcal lesion by the following specific signs:
- Painfulness — there is a complete absence of pain sensitivity (anesthesia) at the ulcer and carbuncle stage.
- Nature of the exudate — complete absence of purulent discharge (serosanguinous contents).
- Appearance — formation of necrotic tissue in the form of a hard black eschar.
- Secondary eruptions — presence of a rim of small satellite vesicles ("necklace" sign) around the eschar.
- Edema — sharply pronounced, extensive "gelatinous" edema of the surrounding soft tissues.
What laboratory diagnostic methods, in addition to bacteriological culture, are used to confirm anthrax?
To confirm anthrax, in addition to the bacteriological method, the following laboratory tests are used:
- Serological method — detection of specific antibodies to pathogen antigens (Bacillus anthracis) using indirect hemagglutination assay (IHA), ELISA, and fluorescent antibody test.
- Allergological method — performing an intradermal test with a specific allergen (anthraxin).
- Biological method — inoculation of laboratory animals (guinea pigs) to isolate the culture.
- Molecular genetic method — rapid diagnostics using PCR.
- Rapid diagnostics — use of the direct fluorescent antibody (DFA) test.
What antibacterial drugs are used for the conservative treatment of anthrax?
For the conservative treatment of anthrax, etiotropic antibiotic therapy with broad-spectrum drugs is used. In clinical practice, the following antibacterial drugs are prescribed:
- Ciprofloxacin — an antibiotic from the fluoroquinolone group;
- Benzylpenicillin — a penicillin-series drug;
- Erythromycin — an antibiotic from the macrolide group.
Additionally, other chemotherapeutic agents may be included in the treatment regimen. The choice of specific drugs, their dosages, and the duration of courses strictly depend on the clinical form and variant of the disease course.
What severe complications can develop with the generalization of the cutaneous form of anthrax?
With the generalization of the cutaneous form of anthrax, life-threatening systemic complications and damage to internal organs can develop:
- Anthrax sepsis — severe generalized infection;
- Meningoencephalitis — hemorrhagic inflammation of the membranes and substance of the brain ("cardinal's cap" sign);
- Hemorrhagic pneumonia — specific lung damage;
- Hemorrhagic enteritis — bowel damage involving lymph nodes and the spleen;
- Mediastinitis and exudative pleurisy — develop when mediastinal lymph nodes are involved.
In addition, when inflammatory edema is localized on the face and neck, its spread to the upper respiratory tract with the development of asphyxia is possible.
Remember the rule of "Three NOs" for an anthrax carbuncle: DO NOT incise, DO NOT excise, DO NOT remove the eschar. The surgeon's scalpel here is a direct path to sepsis.
Class and exam questions
Why is surgical treatment of the carbuncle contraindicated in anthrax?
Any excision, incision, or removal of the eschar destroys the local barrier and leads to the rapid generalization of the infection, which is fraught with the development of severe sepsis.
Which diseases should the cutaneous form be differentiated from?
First of all, differential diagnosis is carried out with a furuncle, a regular staphylococcal carbuncle, and the bubonic form of plague.
What biological material is used to confirm the diagnosis?
For bacteriological examination, the discharge from the vesicle, the formed black eschar, or the discharge from the ulcer is taken for seeding.
What else to study on this topic
- Pathogenesis of black eschar formation and anthrax toxin
- Differential diagnosis features compared to staphylococcal carbuncle
- Specifics of managing patients with facial and neck lesions
- Mechanism of infection generalization upon lesion trauma
- Antibiotic therapy and prophylaxis regimens
Master the entire topic in the "General Surgery" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on «Anthrax in Surgery» and 3,335 more subject pages
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 70 video lessons on the subject
Other topics in «CHAPTER 12. SPECIFIC SURGICAL INFECTION»
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.