Question
A 30 years old male patient suffering with intense headache, abdominal discomfort since 6 days. He developed fever of remittent type with gradual rise in a step ladder fashion. On examination he was toxic with temperature of 101.40F, tongue was coated and mild splenomegaly present. What is the most probable diagnosis. Name the causative agents. Describe the pathogenesis of this disease Describe in detail the sample collection and laboratory diagnosis of this condition. Name four drugs used for treatment Discuss the preventive measures (2+2+3+1+2)
Answer
Most probable diagnosis and causative agents: Enteric (typhoid) fever — headache, abdominal discomfort, step-ladder remittent fever, toxic look, coated tongue, and mild splenomegaly are classical. Causative agents: Salmonella enterica serovar Typhi (Paratyphi A/B/C cause the milder paratyphoid variant).
Pathogenesis Ingested bacilli survive gastric acidity and invade ileal mucosa via M cells overlying Peyer’s patches; taken up by macrophages, in which the facultative intracellular organism survives and multiplies, it spreads to mesenteric lymph nodes and then via the thoracic duct into blood (primary bacteraemia, usually asymptomatic). The organism seeds the reticuloendothelial system (liver, spleen, bone marrow, gallbladder), multiplies during the incubation period, and re-enters the blood (secondary bacteraemia), producing the clinical illness — the step-ladder fever reflects successive waves of bacteraemic seeding. Peyer’s patch hyperplasia can progress to necrosis and ulceration over the terminal ileum, risking haemorrhage/perforation; the gallbladder may harbour the organism chronically (carrier state).
Sample collection and laboratory diagnosis
- 1st week: Blood culture (highest yield during bacteraemic phase; bile broth neutralises antibacterial serum activity).
- Throughout illness: Bone marrow culture (most sensitive at any stage, even after antibiotics).
- 2nd–3rd week: Stool and urine culture, as the organism localizes to the gut/gallbladder/kidney.
- From ~2nd week: Serum for Widal test — demonstrates a rising titre of O and H agglutinating antibody in paired sera; limited by cross-reactions and background titres in endemic populations.
- Newer methods: Typhidot/IgM dot-EIA for rapid diagnosis, PCR where available.
Four drugs for treatment: ceftriaxone (third-generation cephalosporin, current first-line for uncomplicated typhoid in many settings), azithromycin, fluoroquinolones (e.g., ciprofloxacin, though resistance is increasingly common), and chloramphenicol (historically first-line, now largely reserved due to resistance and toxicity concerns).
Preventive measures Safe drinking water and sanitation, proper sewage disposal, food hygiene, hand hygiene; typhoid vaccination (Vi capsular polysaccharide vaccine, Vi-conjugate vaccine, or live attenuated oral Ty21a vaccine); identification and treatment/occupational exclusion of chronic carriers, especially food handlers.