Enteric fever/typhoid and paratyphoid Flashcards
What is typhoid fever?
Systemic illness caused by salmonella typhy and paratyphi A,B and C causing septicaemia
When dose non typhoidal enteric fever occur
Immunocompromised or super imposed infection in chidlren with zoontoci salmonella
Endemic regions typhoid
India/south east asia
Sub saharan africa
Central/south america
WHo is typhoid most common in in endemic areas
Children and young adults
Causative organsims of salmonella
S.typhi
S.paratyphi A+B
Paratyphi C
How is typhoid spread
Faeco-oral - water and food
Or close contact with people or patients or carriers asypmtomatic
Insects and flies - contaminating foods
What strain of typhoid vomitting and diarrhoea before other symptoms and more predominant
Paratyphoid A+B - already multiplied in food
Which salmonella strain causes septicaemia and abscesses without gut involvement
Paratyphoid C
Antigens from salmonella general vs typhi
3 antigens
All salmonella - Smoatic - O antigen
Flagella - H antigen
Typhi and paratyphi also have Vi (coats O antigen)
What factor about contraction of typhoid effects severity of disease
Dose -related
Higher dose = more severe, shorter incubation period
Why do PPIs and H2 antagonists increase the risk of enteric infection
Lower stomach acidity - lower level of salmonella typhi needed to contract typhoid
What are the most important reservoirs for infection
Asymptomatic, convalescent or chronic human carriers eg food handlers
Pathology of enteric fever
Salmonella typhi -> Small intestine -> lymphatics -> mesenteric lymph nodes -> thoracic duct -> blood stream -> gall bladder, spleen, bone marrow, liver
Multiply inside macrophages at these sites
Re-enter blood stream -> symptoms
How is the bowel affected in enteric fever
Baceria collect in peyers patches and other intestinal lymph follicles
Strong inflam response -> hyperplasia, necrosis and ulceration after 7-10 days
Complications of gut inflammation in typhoid
Blood vessel involvement - bleeding
Perforation
Where do typhoid nodules occur
Initially liver, spleen, bone marrow and lymph
Diffuse -> Myocardium, kidney, lung
Abscess formation - bone, brain, liver, spleen
What are typhoid nodules
Aggregated infected macrophages with salmonella typhi
When does fever classically return to normal in typhoid
3 weeks
Fatal complications of eneteric fever
Perforation
Haemodynamic shock ass w intestinal haemorrhage or severe toxicaemia
Meningitis
Average incubation period of typhoid
14 dyas
Can be <7 days to 3 weeks
Fever features in typhoid
Sustained through illness
Increases gradually in first week - evening rise
High or sustained fever of 39-40 degrees C progresses in 3rd and 4th week
Symptoms of typhoid
Malaise, aches and pains, anorexia
Abdominal pain or discomfort, diarrhoea, headache, constipation, non productive cough
Stage 1 and 2 typhoid symptoms
slowly rising - stepladder temp 4-5 days
Abdo pain and myalgia
Malasia
Headache
Constipation
Relative bradycardia
Stage 2 - progression of these in 2nd week
End of 1st week signs of typhoid
Rose spots on upper abdomen and back
Cough
Splenomegaly
Abdo distension w tenderness
Diarrhoea
Typhoid at end of 2nd week
Delirium, complications, coma and death if untreated
Severe dehydration
Delirium ass w typhoid
Muttering delirium
Disconencted and flattened affect
May also have meningism
Rash in typhoid
Rose spots
Rose spots characteristics
Fair skin only
Day 7 onwards
Pink macules
sCANT, mainly on trunk
Disappear under glass
What is a feature of typhoid with high fever that differentiates it
Relative bradycardia of <100BPM
Illnesses displaying relative bradycardia with fever
TYPHOID
yellow fever - flavivirus
Tularemia
Brucellosis
Colorado tick fever
Leginoalla pneumonia
Mycoplasma pneumonia
Complications of typhoid
Bowel - perforation, haemorrhage
Septicaemia foci - bone and joint infection, menningitis, cholecystisi
Toxic phenomena - myocarditis - chest pain, HF, nephritis (renal failure, acute nephrotic syndrome)
Chronic carraige - persistent gallbladder carriage
How is typhoid carried chronically
Persistent gallbaldder carriage eg gallstones
When do bowel perforation occur
3rd week
Sing of peritonitis in toxic patients
Abdo distension
Increasing toxamia
Rising pulse
Treatment for bowel perforation
Surgery - excision or segmental resection
What should do with medications in typhoid at risk of bowel perforation
Widen antibiotic spectrum cover GI orgnaisms contaminate peritoneim
INvestigations for typhoid
Blood culture in 1st/2nd week
Bone marrow culture
Aspirates - Rose spots, CSF, abscess
NOT stool!
Why can bone marrow culture be preferable to blood culutre in typhoid
Higher positivity rate - 10 x concentration in bone marrow of bacteria
Blood - low conc of bacteria
Widal test pros and cons
Cheap, widely availabel
Low sensitivity, specifiticty (general pop have low levels, many slamonella have these antigens, H antigen stays high long time after vaccination, titre rise before clinical onset, some culture + patients show no rise in tire)
What test use for serology of typhoid
Widal test - measures anitbodies to somatic O and flagella H antigens
Prev effective antibiotics for typhoid
Chloramphenicol
Amoxicillin
Cotrimoxazole
Current treatment of typhoid antibiotic choice
Fluoroquinolones w ciprafloxacin or ofloxacin for 5-7 dyas - rapid reaction
3rd gen cephalosporins eg ceftriazone, ceflotazime
Azithromycin
What use as marker for resisteance in fluoroquinolones
Nalidixic acid resistance - proxy marker
India, vietnam have resistant strains
Benefits of 3rd gen cephalosporins and azithromycin for typhoid
Effective against MDR strains, severe disease but slower resposne
What is teh chronic carrier state in typhoid
Several months post infection - biliary or urinary carriage of salmonella typhi
Variabel/erratic excretion
Treatment for carriers of typhoids
ciprofloxacin 750mg for 28 dyas
Cholecystectomy if gallstones - difficult to clear
Convalescent vs chronic carriers
Convalescent - spontaneouslty terminates after several months post infection
Chronic - persisting focus in gallbladder or urinary tract
Feautres of chronic carriers of typhoid
Gallstones, chronic cholecystitis , chronic schistosoma in urinary tract
