Treatment of GI Infections Flashcards
What are the major anaerobic genuses of the gut, and are they more common than aerobes?
Bacteroides, Clostridium, peptostreptococci
Outnumber aerobes 100:1
What are the major aerobic genuses of the gut?
PEK - E. coli, Proteus, Klebsiella, enterococcus
When do we cover enterococcus?
Only when it is cultured, because there is question as to whether it’s even pathogenic
What is the most resistant anaerobe and what is good against it?
Bacteroides fragilis
Usual: Beta-lactam / b-lactamase inhibitors, metronidazole, or cefoxitin (2nd generation GI)
What is the aerobe we try to empirically cover and what is good against it?
E. coli
Sensitivities vary greatly from location to location (hospital to hospital), so just know general susceptibility profiles
What must be covered in a nosocomial or a previously antibiotically treated peritonitis vs a community acquired?
In CA, we typically don’t cover enterococcus.
If nosocomial, we cover P. aeruginosa, Enterococcus, and Candida spp.
What is SBP and what causes it?
Spontaneous bacterial peritonitis (primary peritonitis)
Complication of impaired liver function / cirrhosis which lowers albumin, leading to loss of oncotic pressure in blood vessels and subsequent ascites. Bacteria can translocate into peritoneum during ascites.
What are the most common causative organisms of SBP?
E. coli, Klebsiella, Streptococccus spp. (facultative anaerobes)
What is the mainstay of treatment for SBP? How long?
3rd generation cephalosporins, i.e. ceftriaxone
Short course: 5-7 days
What is given as prophylaxis for SBP if there has been a previous episode or a GI bleed?
Bactrim 5 days a week or Ciprofloxacin once weekly.
A fungus is isolated in SBP. When should you treat?
Unnecessary to treat unless patient is immunocompromised or infection is recurrent
What are other common intra-abdominal infections? What is cholangitis?
Abscesses, ruptured bowel, cholangitis (inflammation of bile duct)
What typically causes other intra-abdominal infections?
Normal flora (i.e. B. fragilis or E. coli)
How do we treat community acquired vs nosocomial or critically ill CA intra-abdominal infections
CA: treat E. coli empirically based on location with a cephalosporin + metronidazole for B fragilis
Nosocomial: Expand coverage to cover Pseudomonas, i.e. Cefepime /metronidazole or Piperacillin/tazobactam
When is acute cholecystitis treated and why?
Only when an infection is expected -> often only an inflammatory condition
Treat the same causative organisms as an intra-abdominal infection
What is most critical in determining the duration of treatment for an intra-abdominal infection? What is your benchmark of stopping?
Typically 4-7 days is good, but need source control (i.e. draining abscesses / checking inoperable abscesses via X-ray or CT)
Benchmark of stopping: GI function return, no fever, WBC decreases
What is the first thing we do when a patient comes in with infectious diarrhea?
Initiate rehydration + perform clinical evaluation including fecal studies
When should we give antimicrobial therapy for diarrhea?
Travelers diarrhea, Shigella, Campylobacter, some C. difficile infections
When should we really avoid giving anti-motility (anti-diarrheal) drugs?
Toxin-producing bugs, i.e. bloody diarrhea, EHEC, C. difficile.
We gotta poop that toxin out
What is the recommendation for anti-microbial treatment of Salmonella?
Not routinely recommended, except in severe disease or extreme agents
What are the two recommended treatments for Salmonella / Shigella?
Either Ciprofloxacin or Amoxicillin / Ampicillin (HELPS)
What are the treatment courses for Salmonella / Shigella in normal / immunocompromised or relapsing patients? Which is a shorter duration?
Salmonella = 5-7 days like SBP for normal Shigella = 3-5 days
Salmonella = 14 days for immunocompromised / relapse Shigella = 7-10 days for immunocompromised
Typically, Shigella has shorter durations
What is the duration of therapy for E. coli and what is the mainstays of therapy?
3 days
Typically cephalosporins or Cipro or bactrim
What is the #1 treatment for Aeromonas and how long?
Ciprofloxacin - 3 days
What is the number 1 treatment for Vibrio, and what do you do if you can’t use that agent?
Doxycycline 300 mg x 1 (triple the normal dose)
If child under 8, use TMP/SMX x3 days, or 1 dose FQ
What is the treatment / duration of choice for Giardia?
Metronidazole x7-10 days
For Traveler’s diarrhea, why are antibiotics of secondary importance?
Hydration is key! Electrolyte abnormalities can cause cardiac arrythmias which are acutely fatal
How do we treat Traveler’s diarrhea in children?
Avoid tetracyclines - tooth damage
Avoid FQ - cartilage damage
Bactrim and Beta-lactams are a good option
What is the mainstay of antibiotic treatment for Traveler’s diarrhea?
Fluoroquinolones
What are two things which can exacerbate C. difficile infections?
- Broad spectrum antibiotics
2. Acid-suppressive agents (i.e. PPIs), blocking your major immune function
What is the first choice treatment for mild-moderate C. difficile and how is this defined?
Metronidazole
Defined as lack of systemic complication, with normal WBC and serum creatinine (showing no acute renal disfunction)
What is the first line treatment for severe C. difficile infection?
Oral vancomycin
What is the duration of therapy for C. difficile?
10-14 days on first instance… afterwards just do an FMT honestly
What is the mechanism of action of Fidaxomicin? Why might it be preferable to oral vancomycin? Why not?
Inhibits RNA synthesis by inhibiting RNA polymerases - bactericidal
Preferable due to lower recurrence rates overtime
Problem: Super expensive
What is the post-exposure prophylaxis to HBV?
Vaccine + HBVIg = antibodies to HBV
What are the treatment options to HBV?
Interferon-alpha, and some HIV meds (lamivudine, adefovir)
What are the mechanisms of action of interferon-alpha?
Inhibits viral protein synthesis, viral penetration, and viral uncoating directly
Also BOOSTS host immune response
When and how is IF-alpha given?
Typically in Hep C or acute Hep B, otherwise in Hep B the HIV antivirals are better
Given subcutaneously or intramuscularly, often conjugated to polyethylene glycol (Pegylated) to allow weekly option rather than 3x weekly.
What are the side effects of IF-alpha?
Flu-like syndrome when drug is administered
Thrombocytopenia / granulocytopenia
Severe depression (give with SSRI)
Rash / alopecia
What was the old regimen for Hep C?
24-48 week course of interferon-alpha + Ribavirin, a guanine analog also used in RSV.
Had very toxic side effects = hemolytic anemia and renal insufficiency. Also poor SVR
What is SVR?
Sustained virological response - essentially a full cure with no HCV in blood after 24 weeks off treatment.
