Actinomycosis

Mechanism of infection and morphology

The pathogen enters the body through contact with the mucous membranes of the mouth, pharynx, bronchi, or intestines. Most commonly, infection occurs when chewing and swallowing cereal grains, as well as by inhaling microparticles of hay or straw inhabited by the fungus.

In response to the pathogen's invasion, a chronic productive inflammation is triggered—a specific granuloma is formed. An infiltrate develops in the tissues, characterized by extreme, "woody" density. It grows incessantly, involving and destroying neighboring structures. Gradually, areas of softening emerge deep within this formation: liquid pus accumulates, containing specific colonies — fungal druses.

The process concludes with the rupture of pus, forming deep ulcers or tortuous sinus tracts. Notably, the regional lymphatic system does not react to a pure fungal infection. Lymphadenitis occurs exclusively when secondary purulent microflora joins (resulting in the formation of abscesses or phlegmon). The most formidable complication is considered to be actinomycotic sepsis, which develops when blood vessels are destroyed by the infiltrate.

Cervicofacial form

This is the most common variant of the disease, accounting for 50% of cases. The inflammation localizes in the neck and lower jaw region. The disease develops insidiously, without prominent acute symptoms.

Trismus (spastic jaw clenching) is one of the earliest and most characteristic signs. As the condition progresses, the masticatory muscles swell and become indurated, and the process spreads to the subcutaneous adipose tissue, skin, and sometimes bone structures.

Objectively, the physician detects a fused with tissues, completely immobile infiltrate. The skin over the angle of the mandible thins and acquires a characteristic bluish-purple hue. Subsequently, the infiltrate breaks down through multiple tortuous sinuses. The pus draining from them has a liquid consistency, is odorless, and contains small dense inclusions—druses. This pathology must be differentiated from neoplasms and tuberculous lymphadenopathy. The prognosis for facial and neck involvement is favorable even in late stages.

Abdominal and thoracic actinomycosis

Intestinal (abdominal) actinomycosis In the abdominal cavity, the ray fungus most frequently attacks the ileocecal region: the appendix and the cecum. The infiltrate penetrates the intestinal wall completely, involving the peritoneum and the anterior abdominal wall. Upon palpation, the abdomen in the affected area feels like a dense, immobile tumor. Tissue destruction leads to mucosal ulcers and external sinuses (purulent or fecal). Granuloma growth into the urinary bladder, retroperitoneal tissue, or kidney is dangerous. The main difference from an appendicular infiltrate: the latter arises after acute appendicitis and regresses with anti-inflammatory therapy.

Pulmonary (thoracic) actinomycosis Granulomas proliferate in the pulmonary parenchyma, involving the pleura, chest wall, bronchi, mediastinum, and diaphragm. Tissue breakdown occurs with the formation of cavities and sinuses. Pus is either expectorated (if the infiltrate ruptures into a bronchus) or discharged through the chest wall. The disease runs a course of years, causing severe pneumosclerosis. Initially, the clinical picture mimics chronic bronchopneumonia that does not respond to antibiotics. For the early stages of these two forms, the prognosis is favorable; for advanced stages, it is unfavorable.

Diagnosis and management tactics

Confirming the diagnosis requires carefully ruling out cancer and pulmonary tuberculosis using radiography, CT, and bronchoscopy. A specific process is indicated by the relentless growth of the induration, its breakdown, and resistance to antibacterial drugs.

The "gold standard" of diagnostics is microscopy of discharge (pus, sputum) or biopsy specimens (skin, lymph nodes). A definitive diagnosis is established only upon visual detection of actinomycete druses. Material for analysis in internal organ involvement is obtained during bronchoscopy or thoracoscopy.

• Conservative therapy: Forms the basis of treatment. Patients are prescribed iodine preparations (e.g., potassium iodide) combined with radiotherapy.
• Surgical treatment: Used when medications and radiation therapy are ineffective. It includes resection of the affected area (lung lobe, intestinal segment). In emergency situations (purulent mediastinitis, pleurisy, retroperitoneal phlegmon), palliative operations are performed—wide opening and drainage of purulent foci.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Pathophysiology of the development of actinomycotic sepsis
• X-ray and CT signs of lung involvement in actinomycosis
• Features of the differential diagnosis of actinomycosis and tuberculosis
• Surgical approaches for draining retroperitoneal phlegmon
• Mechanism of action of iodine preparations in specific fungal infections

Other topics in «CHAPTER 12. SPECIFIC SURGICAL INFECTION»

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