Gastro Flashcards
Discuss campylobactor
Most common cause of gastroenteritis in developed countries and common cause of travellers diarrhoea
Most common is jejuni, coli and fetus
They produce disease via direct invasion of the colonic epithelium
Incubation is 2-5 days- with radid onset of fever, cramping abdominal pain and diarrhoea. Constituinal symptoms of anorexia, malaise and myalgia are the rule. Stools can become grossly bloody in about 40% of cases.
Supportive management is mainstay for those not improving azithromycin 500mg OD for 3 days
Complications are rare but include
- cholecystitis
- pancreatitis
- massive GI bleeding
Discuss salmonellosis
Ingested from contaminated food or drink
Most common serotypes are the S. typhi (typhoid fever), S choleraesuris, typhimurium
Incubation of 8-48 hours
fever colicky abdominal pain, loose watery stools and occasional blood or mucous.
Not routinely treated with ABs if needed azithromycin 1g followed by 5oomg a day for 6 days.
Complications incude
-Reiters syndrome - consisting of reactive arthritis, conjunctivits and urethritis
Briefly outline enteric fever (typhoid and paratyphoid)
First week - illness with rising fever and bacteremia develop. Relative bradycardia or pulse-temperature dissociation may be observed.
Second week abdominal pain develops with rose spots (faint salmon coloured macules on the trunk and abdo) ,may be seen
Third week - hepatosplenomegaly intestinal bleeding and perforation dur to ileocaecal lymphatic hyperplasia may occur, together with secondary bacteremia and peritonoitis .
In the absence of acute complications or death from overwhelming sepsis symtpoms gradually resolve over weeks to months
Ceftriaxone 2g is the antibiotic of choice for severe typhoid fever
Describe shigellosis
Infection are common in confined populations such as those in mental or penal institutions, in nursing home or daycare centres.
Incubation is 24-48 hours and clinical manifestations vary considerably often appearing in a bimodal fashion.
Mild watery diarrhoea with few if any constitutional symptoms
When dysentery develops patients have grossly bloody diarrhoea tenesmus and constitutional symptoms and signs such as fever nasuea vomiting and headache.
Generally self limiting specific serotypes have been asscoiated with HUS
Describe Yersinia enterocolitica
Bacterium invades the intestinal epithelium and localises to the lymphoid tissue of the intestinal mucosa particularly Peyer’s patches. It then invades the regional mesenteric lymph nodes
Invasive enteritis is the clinical presentation in 2/3 with other 1/3 presenting as pseudoappendictis and mesentertic adenitis.
Clinical picture is usually similar to that of other enteritis with fever, diarrhoea and colicky abdominla pain. In a substantial number of patients particualry adolescents and young adults an ileocecitis may develop. In these cases lower abdo pain with little or no diarrhoea is the predominant symptoms and can be impossible to differentiate appendicits
Complictioans
- erythema nodosum
- polyarthritis
- sacroiliotis
- ank spond
- reiters syndrome
- pneumona
- lung abscess
Describe enterohaemorrhagic e.coli
E.coli serotype 0157:H7 is one of more than 30 serotypes known to produce STEC
STEC serotypes constitue a major cause of haemorrhagic colitis, HUS and thrombotic thrombocytopenia purpura
STEC multiply in competition with normal bacterial enteric flora adhere to the intestinal epitheal cells and elaborate Shiga toxin. Toxins bind to absorptive enterocytes enter the cell and irreversibly inhibit protein synthesis resulting in the death of the endothelial cells. They then enter the blood stream and cause the death of vascular endothelial cells by the same mechanism. Endothelial cell lysis is accompanied by platelet activation and aggregation leading to thrombocytopenia. Microangiopathy propagates distally as the toxins are carried to the kidney causing the clinical syndrome of haematuria and renal failure
Discuss clinical features of enterohaemorrhagic e.coli
After an incubation period of 3-4 days patients initially produce watery diarrhoea that becomes blood hours to days later. The amount of blood varies but stools passed may consist wholly of blood and mimic GI bleeding.
Typicallyis accompanied by severe abdominal cramping pain and often vomiting.
STEC collitis has been associated with two serious complications HUS and TTP: THese clinical similar disorders shar the features of microangiopathic haemolytic anemia, thrombocytopenia, fever, neurolgoical deficits and renal dysfucntion.
In TTP neurological finding predominate and renal manifestations are rare the inverse is true of HUS
Discuss management of STEC collitis
Supportive
Antibiotics are of nil clinical benefit and may increase the risk of HUS by eliminating competing bowel flora.
Empirical antibiotics for bloody diarrhoea should be approached with caution it is not recommended in children because of the risk of HUS and is only recommended in adulrs wiht fever >38.5 as the pressence of signficant fever suggest pathogen other than e.coli 0157:H7
Discuss Staph induced enteritis
Staph related food poisoning occurs after mulitplication of an enterotoxin fomring strain of staph that is present in the food before ingestion
Staph enterotoxin is heat stable. The toxin has not local effect on the GIT. It is a potent stimulator for t lymphotcyte in the host resulting in their proliferation and the release of cytokines. THe GI effects are belived to be mediated by the release of IL2
The illness has an explosive onset beginning 1-6 hours after ingestion of the contaminated food. Cramping and abdo pain with violent and often repeated retching and vomiting are predominant. Diarrhoea is a variable feature - short lived usually subsiding after 6-8 hours.
Discuss C.PERFRINGENS
Release type a heat resistant spores.
Diarrhoea onset 6-12 hours usually resolving at the 24 hour makr
Self limiting
Discuss cholera
Cholera virbrio speceies produce enterotoxin in vivo that stimulates enterocyte adenylate cyclase disrupting mucosal fluid absorption leadin to a secretory dirrhoea.
Patient classicly present with rice water diarrhoea abdominal cramps and often nausea and vomiting within 24-48 hours of ingestion of contaminated seafood.
Low grade fever may be present
In severe cases the rate of diarrhoeal fluid loss can reach 1L/hour and fatality rates can reach 25-50% in untreated population.
Median duration is 7 days
Management include fluid replacement ideally ORT if available and tolerated
Antibiotics include a single oral dose of cipro 1g, azithro 1g or doxy 300mg for 3 days.
Discuss C.diff
An anaerobic spore forming gram positive bacillus
It has been associated with a range of illness from asymptomatic to
-Severe diarrhoea
-Pseudomembranous colitis
-toxic megacolon
-intestinal perf
-death
C.diff infections are usually related to antibiotics use that alters the gut flora and allows bacteria to colonize and proliferate. Can manifest concomitantly with current antibiotic use and up to 3-4 weeks afterwards although most C.difficile infection will occur within 2 weeks of using an antibiotic
List antibioitics frequently associated with c.diff
Fluroquinolones clindamycin Penicllins and combinations Cephalosporins Carbapoenems
Discuss clinical features of c.diff
Watery diarrhoea up to 15 times a day with lower abdominal pain cramping and low grade fever
Look for signs of dehydration and bowel perforation
Discuss diagnosis of c.diff
PCR for c.diff toxins A and B (NAAT)
Culture
