Makindo Medical Notes.com

The heart rate and WCC may be surprisingly low for the degree of systemic upset.

About

• Typhoid fever: Salmonella typhi
• Paratyphoid fever: Salmonella paratyphi

Aetiology

• Children aged 1-5 years are at the highest risk of infection
• Spread faeco-oral through foodstuffs.
• Gallbladder may act as a reservoir even in those "treated".
• Bacilli localise to the small intestine lymphatic tissue - "Peyer's patches" which can swell, ulcerate and bleed

Characteristics

• Motile Gram-negative rods Facultative anaerobe
• Glucose fermenting Oxidase negative catalase-positive
• Reduces nitrates to nitrites
• Does not ferment lactose and so produce pale colonies on MacConkey's agar
• Resistant to sodium deoxycholate (bile salts)

Clinical

• Incubation period 10-14 days for Typhoid and shorter for Paratyphoid
• Classically has been divided into 3 weeks of symptoms and signs and complications
• Week 1 "Week of symptoms" - Dry Cough, Malaise, Headache, rising step like Fever 39°C. May be constipation or diarrhoea. Relative bradycardia despite fever.
• Week 2 "Week of signs" - Rose spots (bacterial emboli) on abdomen and thorax, Epistaxis, Prostration, Shock, Coma, Relative Bradycardia, Splenomegaly, Hepatomegaly, Cervical lymphadenopathy
• Week 3 Complications - Toxaemia, Small bowel haemorrhage, Intestinal perforation, Cholecystitis, Osteomyelitis (sickle cell disease), Myocarditis, Nephritis, Meningitis, Pneumonia. Week 3 is when patients die of complications.
• Week 4 - Recovery
• Long term: Some are asymptomatic carriers and excrete Salmonella typhi in their faeces due to a reservoir in the gallbladder.
• Paratyphoid fever is similar to the above but less severe. The course tends to be shorter and milder and the onset is often more abrupt, with acute enteritis. The rash may be more abundant and the intestinal complications less frequent

Bone and joint infection is common in children with sickle-cell disease.

Investigations

• FBC: ↓ WCC ↑ AST/ALT
• Positive blood cultures weeks 1/2 for S. typhi or paratyphi
• Positive stool cultures weeks 2/3 for S. typhi or paratyphi
• Positive urine cultures for S. typhi or paratyphi
• Widal test unreliable and only of historical information

Management

• Untreated typhoid fever lasts at least 4 weeks
• Ensure immediate Side room Isolation and strict hygiene
• Start Ciprofloxacin 500-750 mg BD (up to 500 mg QDS) PO for 10 days
• Alternative may be Azithromycin for 10-14 days
• Carrier status requires Ciprofloxacin 500 bd PO for 4 weeks
• Some chronic carriers may require a cholecystectomy
• Notifiable disease in UK so contact local CDDC.
• An infected patient cannot return to food handling until they have had negative stool cultures.
• Prevention in travellers with IM capsular polysaccharide vaccine