ABX for Diarrhea Flashcards
Drugs for Infectious Diarrhea
Fluoroquinolones (-oxacin) Trimethoprim-Sulfamethoxazole Antiprotozoal (Metronidazole) Others (Vancomycin) Symptomatic Therapy- Bismuth subsalicylate, opioid agonists
bacterial meningitis, gram-positive diplococci- what is it?
strep pneumo
agent that inhibits the enzyme responsible for bacterial cell wall transpeptidation. Choose from below:
Azithromycin Ceftriaxone Doxycycline Levofloxacin Trimethoprim-sulfamethoxazole
Answer: Ceftriaxone (3rd gen cephalosporin)
azithromycin is a macrolide
doxycycline is a tetracycline
levofloxacin is a fluoroquinolone
trimeth is a sulfonamide
On ceftriaxone for bacterial meningitis, now diarrhea with cramping pain, mucoid, greenish foul-smelling watery stools. Temp 101.3, stool sample positive for fecal leukocytes.
What is this? Best management?
c. diff (antibiotic-associated)
gram-positive, spore forming bacillus
begin directed therapy for C. diff but do not discontinue the ceftriaxone (meningitis!)
antimicrobials that may induce C diff diarrhea
Frequently: fluoroquinolones, clindamycin, cephalosporins, penicillins
occasionally: macrolides, trimethoprim-sulfamethoxazole
Rarely: aminoglycosides, tetracyclines, metronidazole, vancomycin
Appropriate initial treatment for c diff associated diarrhea?
vancomycin and metronidazole
(vanco binds D-Ala-D-Ala and inhibits bacterial cell wall synthesis)
(metronidazole damages bacterial DNA via nitro radical groups)
For severe and complicated, can combine the two drugs
what ginds DNA gyrase?
fluoroquinolone
What prevents folic acid synthesis?
sulfa drugs
how do we choose between metronidazole and vancomycin for c diff?
can they handle oral? (vanco can be given IV)
They are equally efficacious in mild, but for severe, vanco is superior
vanco is also super expensive, so for mild (leukocytosis of 15,000 cells/ microLiter or lower and creatinine 1.5 times the premorbid level) we use metronidazole
other ways to get c diff besides abx
c diff spores (nosocomial)
ADR of fluoroquinolones
achilles tendon rupture
ADR of tetracyclines
photosensitivity
ADR of macrolides
QT prolongation
ADR of vancomycin
ab pain, bad taste, nausea
metronidazole can also cause bad taste.
IV antibiotics and diarrhea?
not appropriate; doesn’t get to the GI tract
if oral won’t work, let’s do rectal or through ileostomy
traveler’s diarrhea treatment
often e coli
management: oral rehydration would be critical
fluoroquinolones to shorten the diarrhea from 3-4 days to 1-2 days
symptomatic therapy for diarrhea hat works by inhibiting intestinal prostaglandin and chloride secretion
bismuth subsalicylate
How does aprepitant work?
NK-1 receptor antagonist, for nausea and vomiting
bisacodyl works how?
stimulant laxative
diphenoxylate is what?
opioid agonist
loperamide is what?
opioid agonist
gal with traveler’s diarrhea
The decision is made to begin antibiotic therapy. Which of the following agents would be most appropriate in this case? Azithromycin Ciprofloxacin Metronidazole Trimethoprim-sulfamethoxazole Vancomycin
ciprofloxacin
undercooked chicken. What diarrhea?
campylobacter
Which of the following would be most appropriate for campylobacter? An agent which inhibits: Cell wall synthesis DNA gyrase DNA synthesis Folic acid synthesis Protein synthesis
Azythromycin or Erythromycin
protein synthesis inhibitor belonging to the macrolide class
campylobacter is resistant to fluoroquinolones (chicken feed?)
sick drinking alcohol, treated with abx.
probably it’s metronidazole
more clues– he had been backpacking and drinking stream water (giardia)
therapy for giardiasis, does what? Inhibits…
Cell wall synthesis DNA gyrase DNA synthesis Folic acid synthesis Protein synthesis
inhibits DNA synthesis (metronidazole!)
don’t take with alcohol!
popular mexican grill, now bloody diarrhea, abdominal tenderness, no fever. What diarrhea?
E Coli (hemorrhagic)
A 50 y/o female with Shiga toxin-producing E. coli (STEC).
The best management for this patient would include:
Azithromycin – to reduce duration of diarrhea from 3-4 to 1-2 days
Ciprofloxacin – to reduce duration of illness 2.4 days
Loperamide – to reduce patient symptoms
Metronidazole – to treat diarrhea if persistent
Supportive care – antibiotics will not affect illness duration
Supportive care!
ABX can make it worse
Glycopeptides MOA, ADRs
Vancomycin (PO, IV)
MOA: * inhibits cell wall synthesis binding with high affinity to D-Ala-D-Ala terminal of cell wall precursor units.
Spectrum: broad gram-positive coverage – S. aureus (including MRSA), S. epidermidis (including MRSE), Streptococci, Bacillus, Corynebacterium spp., Actinomyces, * Clostridium
Therapeutic Use: osteomyelitis, endocarditis, MRSA, Streptococcus, enterococci, CNS infections, bacteremia, * orally for C. difficile
ADRs:
Macular skin rash, chills, fever, rash
Red-man syndrome (histamine release): extreme flushing, tachycardia, hypotension
Ototoxicity, nephrotoxicity (33% with initial trough > 20 mcg/mL)
Fluoroquinolones MOA, ADRs
MOA: concentration-dependent; targets bacterial DNA gyrase & topoisomerase IV.
Spectrum: * E. coli, * Salmonella, * Shigella, Enterobacter, * Campylobacter, Neisseria, Pseudomonas aeruginosa, S. aureus (not MRSA), limited coverage of Streptococcus spp.
Therapeutic Use: UTI, prostatitis, STI (chlamydia, Neisseria gonorrhoeae), * traveler’s diarrhea, * shigellosis, bone, joint, SSTI infections, diabetic foot infections
ADRs:
GI 3-17% (mild nausea, vomiting, abdominal discomfort)
CNS 0.9-11% (mild headache, dizziness, delirium, rare hallucinations)
Rash, photosensitivity, Achilles tendon rupture (CI in children)
Metronidazole MOA, ADRs
MOA: prodrug, requires reductive activation of nitro groups by susceptible organisms. Highly reactive nitro radical anions kill organisms by * targeting DNA
Spectrum: anaerobic cocci and both anaerobic gram-negative bacilli (including Bacteroides) and anaerobic spore forming gram-positive bacilli * (Clostridium), trichomoniasis, * amebiasis, * giardiasis. Helicobacter and Campylobacter.
Therapeutic Use: anaerobic bacterial infections. * Clostridium difficile
ADRs:
Headache, nausea, dry mouth, metallic taste
Vomiting, diarrhea, abdominal distress
Well-reported disulfiram effect
DDIs: induced metabolism of phenobarbital, prednisone, rifampin. Prolongs prothrombin time in those receiving warfarin.
Sulfonamides & Trimethoprim MOA, ADRs
MOA: sulfonamides = bacteriostatic, competitive *inhibitors of dihyropteroate synthase. Synergistic trimethoprim = * inhibition of microbial dihydrofolate reductase.
Spectrum: Broad! * E. coli, Proteus mirabilis, Proteus morgannii, Enterobacter, * Salmonella, * Shigella, Serratia, Brucella abortus, Yersinia pseudotuberculosis, T. enterocolitical, Norcardia asteroids
Therapeutic Use: UTI, bacterial prostatitis, bronchitis, * Shigellosis, * Traveler’s diarrhea, * Salmonella, Pneumocystis jiroveci (fungus) prophylaxis in neutropenia, Nocardia, Stenotrophomonas maltophilia.
ADRs: allergic skin rashes, nausea, vomiting, CNS (headache, depression), photosensitivity, renal dysfunction, Stevens-Johnson syndrome.
