Gastrointestinal infections Flashcards
What are different classes of peritonitis?
Primary - also known as SBP. Usually arises from translocation of bacteria from gut
Secondary - e.g due to surgery, malignancy or peritoneal dialysis
Treat for 5-7 days usually. But may change depending on patient condition, or organism isolated.
Requires surgical review, as may need surgery/ drainage for source control
Patient with peritonitis.
How important is empiric cover against enterococci?
Most common causes are gram neg bacilli, so enterococci less likely cause
amox/ met/ gent will cover the most common causes, including enterococci (although not optimal)
if culture results show enterococci, then add cover
Patient with peritonitis.
Blood cultures show ESBL.
Patient on co-amoxiclav/ gent/ metro
Should antibiotics be changed?
Not necessarily
Co-amoxiclav has clavulanic acid, so can resist ESBL in principle. Better to check MIC to see if is resistant or not.
If so, may need to use meropenem
Options for peritonitis -
amox/met/ gent
taz/ gent
vanc/ gent
cephalosporin/ metro
What are limitations of using cephalosporin in this case?
Does not cover pseudomonas
Does not cover enterococci
Taz does have pseudomonal/ enterococci cover
What bacteria can be implicated in bacterial hepatic abscess?
What is duration of therapy?
Klebsiella pneumoniae
Abscess requires drainage.
Approx 4-6 weeks of antibiotics, usually continued for few weeks after radiological resolution
When is C. Difficile infection classified as
Healthcare associated
Community associated
Healthcare associated -
- symptoms appear on day 3 or later in hospital admission
- symptoms within 4 weeks of discharge
Community associated
- symptoms without being in healthcare facility in past 12 weeks
Unknown association
- symptoms occurring 4-12 weeks after being in healthcare facility
After how long since C. Difficile infection, is it re-occurrence?
if returns within 8 weeks of first episode
occurs in 20% patients
What are treatment options for first recurrence of C. difficile?
If had metronidazole, then give first course of vancomycin
If had vancomycin, then give 14 days, with reducing course
Also consider fidaxomicin, rifaximin, nitazoxinide
Which microbes are associated with travellers diarrhoea?
E. Coli - ETEC. EAEC
Campylobacter
Salmonella - non-typhi
Shigella
Travellers can take antibiotics if at high risk of developing travellers diarrhoea, or would be high risk if developed diarrhoea
What are options?
Azithromycin 500mg OD 3 days - most universally used choice
Ciprofloxacin - 500mg BD 3 days - resistance in SEA
What are most common causes of viral gastroenteritis?
Caliciviruses - norovirus, sapovirus
rotavirus
astrovirus
adenovirus - serotypes 40/41
Describe structure of norovirus
Which genotype causes most infections
+ssRNA
7 genogroups based on VP1 - major capsid protein
within genogroups, there are genotypes
genogroup 2 genotype 4 is most common cause worldwide
Patient with norovirus.
36 hours later, patient in bay has diarrhoea/ vomiting.
12 hours later, further 4 cases are reported within the ward.
What are criteria for identifying outbreak of viral gastroenteritis?
Kaplan criteria can be used to determine probability that cause is viral gastroenteritis
sensitivity 70%
specificity 99%
- vomiting >50%
- mean incubation period 24-48 hours
- mean duration illness 12-60 hours
- no bacterial cause identified
What are the Kaplan criteria, used to identify an outbreak of viral gastroenteritis?
- mean illness duration 12-60 hours
- mean incubation 24-48 hours
- > 50% people with vomiting
- no bacterial agent found
usually triggered if two patients develop diarrhoea and vomiting
Viral gastroenteritis outbreak.
What are some infection control measures
Handwashing - superior than alcohol
Isolate patients
Close bays
Enteric precautions
Do not move suspect patients until 48 hours symptom free
Staff not to return until 48 hours symptom free
HEV infection in immunocompromised can become chronic.
What are treatment options for chronic HEV infection?
Reduce immunosuppression
ribavirin
Which HEV genotypes infect in resource rich, and resource poor countries?
Resource poor -
genotype 1/2 - contaminated water
Resource rich -
genotype 3/4 - zoonosis pigs
What are complications of HEV infection?
Chronic infection - immunocompromised
Fulminant hepatitis - particularly pregnant women infected with genotype 1/2