Infections Of The GI Tract And Related Organs Flashcards
If vomiting occurs after an hour of food consumption, what is the likely microbial cause of food poisoning?
S. Aureus or bacillus toxins. These toxins are absorbed in stomach and act at central vomiting centre.
S aureus can be caused by contamination of salted meat products, seafood and dairy.
B cereus is a gram positive spore forming bacillus that is associated with rice.
Which organism causes food poisoning that is characterised by 12-24 hours after eating there is colicky abdominal pain and diarrhoea?
C. Perfringens. Commonly found in precooked old meats that have been reheated.
Which two bacteria can cause food poisoning like symptoms due to enteritis caused by invasion of intestinal mucosa?
Salmonella or campylobacter
Which organism causes cholera?
Vibrio cholerae
What key symptom does cholera cause?
Diarrhoea
What is the reservoir for cholera infection?
Infected individuals. Hence the disease spreads easily in conditions of poor sanitation and overcrowding.
What is the most common cause of diarrhoea in preschool infants?
Rotavirus
What key symptom is associated with rotavirus infection?
Vomiting
What is Giardia lamblia?
An anaerobic flagellate parasite of the small intestine that causes diarrhoea.
How is giardia spread?
Ingestion of infective cysts in contaminated water.
What is the treatment for giardia?
Metronidazole for at least 5 days.
What are cryptosporidium?
Sporozoan parasites transmitted via drinking water contaminated with faeces of farm animals.
What disease does campylobacter cause?
Infection is limited to intestinal epithelium and causes a secretory diarrhoea . No effective treatment.
What is enteric fever?
A systemic illness caused by salmonella typhi and paratyphi.
Where can salmonella bacteria come from?
Undercooked poultry, eggs and dairy.
Which antibiotics can cause diarrhoea via allowing overgrowth of certain bacterial species?
Clindamycin, most B lactam antibiotics.
Erythromycin can cause diarrhoea and colickly abdominal pain due to effect on gut motility.
What is pseudomembranous colitis?
An antibiotic associated diarrhoea which is accompanied by bloody stools and formation of inflammatory exudate on colonic mucosa. Caused by C.difficile.
How do we treat c.dif related pseudomembranous colitis?
Oral vancomycin or metronidazole.
What causes bacillary dysentry?
Shigella
What are the symptoms of shigellosis?
Varies from mild diarrheoa to severe diarrhoea with blood and pus in the stool.
How is diagnosis of shigella infection confirmed?
Stool culture for Non lactose fermenting gram negative bacillus.
What is hepatitis?
Inflammatory damage occurs to hepatocytes without fibrosis or regeneration.
What organisms cause hepatitis?
Hep A-E
Cytomegalovirus
What are the signs and symptoms of hepatitis?
Raised unconjugated bilirubin levels in blood and urine, raised liver enzymes, discomfort or pain in RUQ, nausea, anorexia.
How is hepatitis A spread?
Via the fecal oral route
What is the epidemiology of hep A?
Common in children exposed to untreated human sewage, rare in patients aged over 40years.
What are the signs and symptoms of hep A infection?
Onset of dark urine and pale stools . Jaundice.
What is the incubation period of hep A?
2-6 weeks.
What is the mode of transmission of hepatitis B?
Blood, blood products and human body secretions eg sexual intercourse.
What is the incubation period of hep B?
6 weeks to 6 months.
What are the sequaelae of hep B hepatitis?
Can range from sub clinical infection to fulminant hepatitis. Can progress on to be a carrier state, or liver failure, chronic active hepatitis and hepatocellular carcinoma caused by malignant transformation.
Who is most at risk of hepatitis B infection?
Male homosexuals, IV drug users, infants of mothers whoa re carriers, renal dialysis patients, recipients of multiple blood transfusions, populations of many african and asian countries where the carrier state is common.
How is diagnosis of Hep B infection confirmed?
ELISA, immunological assay.
How is HbsAg used?
It is a marker of infection but doesnt distinguish active hepatitis after about 6 weeks. Those who remain HBsAg positive after 6 months usually become carriers.
How is HB e antigen used?
It is a good predictor of high level infectivity
In the early stages of hepatitis B infection, what is the first antibody reaction to appear after the surface antigen disappears?
HB core antigen.
What is the difference in treatment of hepatitis B in the early stages of the disease as compared to later on?
In the early stages treatment with interferon may reduce progression of the infection. Lamivudine can also be used for patients who are e antigen positive.
What is the incubation period of hepatitis C?
1-3 months
What is the mode of transmission of hep C?
Via blood and blood products.
What is the most common course of disease in hep C?
Most cases end up as chronic hepatitis
What is a liver abcess?
A focal collection of pus caused by bacteria or by the parasite entamoeba histolytica. The infection may arise following ascending pyogenic infection.
What are the common symptoms of liver abcess?
Fever and RUQ pain.
What are the common bacterial causes of liver abcess?
Enterobacteriaceae or strep.
What is the treatment of liver abcess?
Drainage
Ampicillin, gentamicin and metronidazole.
What is cholecystitis?
An inflammation of the gall bladder
What are the signs and symptoms of cholecystitis?
Fever
Rigors
Abdominal pain
Subcostal tenderness on right side.
Which bacteria are commonly found in acute cholecystitis?
Enterobacteriaceae, enterococci, and anaerobic species
What is the treatment for acute cholecystitis?
Analgesics, bed rest and antibiotics
Cholecystectomy sometimes considered
What is cholangitis?
Biliary tract obstruction caused by infection.
What are the signs and symptoms of cholangitis?
Fever
Jaundice
Chills
What organisms commonly cause cholangitis?
Enterobacteriaeceae, enterococci, anaerobic bacteria.
What is the sequelae of cholangitis?
High percentage of patients have bacteraemic spread. Condition has a high mortality rate, especially after the onset of septic shock.
How is diagnosis of cholangitis made?
Blood culture and diagnostic ultrasound scan.
What is the treatment for cholangitis?
Ampicillin
Gentamicin
Metronidazole
Underlying obstruction of the biliary tract may require surgical intervention.
What are the recognised precipitants of chronic pancreatitis?
Gallstones obstructing pancreatic duct, excessive alcohol consumption, mumps virus infection.
