Bugs & Drugs

Always refer to the Stanford Guide &/or the Green Book put out by the FAHC Infectious Disease Department (written by Dr. Grace) and available to you for free from any of the hospital pharmacies.

You'll find important, basic information on bacterial classification on the Gram Stain Compendium page. Knowing into what category your pathogens fall is crucial to choosing appropriate antibiotics, and is highly fertile ground for pimping.

The general recommendations listed on this page are just intended to get you started, particularly the antibiotic regimens we've included. Opinions vary greatly on which antibiotics are best for which infections.

This is a tricky area, and it seems everyone has their favorite pet antibiotics. You should be able to suggest something reasonable - that seems to be the basic expectation. This list should help, although it obviously won't agree with everyone. It assumes that the patient's presentation is uncomplicated. If the presentation is not a straightforward one, consult Sanford!!

Common Bug/Drug Combos by Organ System:
CSF Infections
Meningitis cultures can take 1-2 days. Empiric coverage in meantime should be  vancomycin while sensitivities are pending, then switch to ceftriaxone if sensitive.
Strep pneumoGPCceftriax, vanc if resistant
Neisseria meningitidisGNCceftriax
H. fluGNRceftriax
Listeria (uncommon)GPRamp
Consider viralEnterovirus (most common)supportive Tx
HSVAcyclovir
Fungalfluconazole or ampho

GI Infections
E. ColiGNRBactrim (only for diarrhea - check Green Book for peritonitis,cholangitis)
C. Diff (most common nosocomial GI infection)GPRFlagyl
Bacteroides FragilisGNR anaerobeFlagyl
Enterobacter Quinolone, 3rd Gen Ceph
EnterococcusGPCDouble coverage - Amp & Gent
H. pyloriTriple regimen (MOC) = metronidazole, omeprazole, clarithro
PseudomonasDouble coverage - Ceftaz & Gent

Community Acquired Pneumonias
Empiric coverage includes azithro ("Z-pack"), e-mycin. Doxycycline is an underused drug with excellent coverage for CAP's.
TYPICALS
Strep pneumoGPCpen (if sensitive), doxy, any ceph (if sensitive), azithro, quinolones (except Cipro)
H. fluGNRdoxy, azithro, any ceph, others
MoraxellaGNCdoxy, azithro, any ceph, others
Klebsiella (uncommon, occurs in alcoholics)GNRdoxy, azithro, any ceph, others
ATYPICALS (slow, indolent course - "walking penumonia" - except Legionella, which packs a punch. Atypicals tend not to show up on gram stain)
MycoplasmaGNRmacrolides, doxycycline, quinolones
ChlamydiaGNRmacrolides, doxycycline, quinolones
LegionellaGNRmacrolides, doxycycline, quinolones
Virusessupportive therapy

Hospital Acquired (Nosocomial) Pneumonias
Empiric coverage includes vanco & cefazolin. If in ICU, Ceftaz is drug of choice.
StaphsGPCvanco, cephalosporins, clinda
Gram NegativesGN3rd generation ceph
PseudomonasGNRDoube coverage - Ceftaz & aminiglycoside. Can also consider piperacillin

Tuberculosis
If simply treating for positive PPD, INH x 12 months.
Proven infection 4 drug regimen.

Bronchitis
USUALLY VIRAL, so no antibiotics - treat with steam, albuterol inhaler PRN. If bacterial:
Strep PneumoGPCpen (if sensitive), doxy, any ceph (if sensitive), azithro, quinolones (except Cipro)
StaphGPCbactrim
MoraxellaGNRazithro
H. fluGPRdoxy
Virusessupportive therapy

Cellulitis
Empiric coverage starts with cefazolin. Often cultures are not helpful.
Staph & StrepGPCcefazolin
MRSAGPCvanco
Diabetics are prone to polymicrobial infections that can be quite deep, and may include GNR's and anaerobes.

Urinary Tract Infections
See Green Book (page 30). Don't treat unless symptomatic (or if pregnant, prior to urologic procedure, or if renal transplant patient) - then empiric therapy is co-trimoxazole (Bactrim, Septra). Note that E. coli resistance to bactrim is increasing - get sensitivities (from culture taken before Tx starts).
Uncomplicated cystitis in females3 daysco-trimox, cephalexin, nitrofurantoin
Complicated cystitis7 daysco-trimox IV, norfloxacin, cefpodox
Pyelo with inpatient Tx14 daysco-trimox, cefpodox, cipro
Pyelo with outpatient Tx14 daysco-trimox, gent +/- amp, cipro

Bugs By Presentation
Pneumonia:
Community acquired (CAP):think "pneumonia on the klam shell: KLMSH": Klebsiella, Legionella, Mycoplasma, Strep pneumo (pneumococcus), H flu. Cover with 3rd gen ceph, zithromax, bactrim.
Institutionally acquired:Staph, GHR's, Pseudomonas, TB. Need Dx.
UTI:Uncomplicated: E coli, cover with bactrim, keflex, quinolone. Proteus?
Pyelo: IV Bactrim
Cellulitis:Gram+ cocci. Cover with kefzol, penicillins.
Diarrhea:if on ABX, consider c.diff (send sample to lab) - cover with flagyl PO, d/c other ABX if possible.
Ulcers: H. pylori. Cover with flagyl, bizmuth (peptol-bizmol), several alternative regimens
TB:cover with rifampin, isoniazid
Abscesses: surgery. Anaerobes.
URI's:Usually viral, so ABX. If bacterial, think Amoxicillin, Erythromycin
Neutropenic Fever: Piper & gent, ceftaz & gent
Drugs By Class
CNS Penetrating:
Good:flagyl, sulfa, chloramphenicol, ciproflaxacin
OK: Amp, cefotaxime, ceftriaxone
Poor:erythro, clinda, cefazolin
PCN:strep, mouth anaerobes, treponemes. staph only with nafcillin or oxacillin. GNR
Amino pen:GNR except pseudomonas
Piperacillin:Primarily used for pseudomonas. Also covers bizarre GNR & serrata
Nafcillin:staph aureus
Cephalosporins:
1st gen (keflex): aerobic gram+ cocci & simple GNR. h flu, neisseria
2nd gen (cefoxitin): staph, strep, h flu, neisseria
3rd gen (ceftriaxone = IV, cefpodox = PO):staph, strep, good GNR, enterobacter, serratia
Macrolides (erythro, azithro, clarithro, biaxin):gram+ cocci, atypical pneumonia bugs, h. flu, chlamydia. Bacteriostatic
Aminoglycosides (gentamycin, tobra, amikacin):Active against aerobic GNR's. Also used for synergy with ceph's or amp against pseudomonas, staph aureus, and enterococcus
Tetracycline:tick-borne & others
Clindamycin:anaerobes & gram+ cocci
Bactrim/Septa:GNR, UTI
Flagyl/metronidazole:anaerobes, c. diff, parasites such as giardia, entamoeba histolytica
Quinolones (cipro, levoquin, trovan):everything except MRSA. Adults only. Trovan is hepatotoxic.
Sulfonamides (bactrim, sulf..., trimethoprim):staph, strep (including strep pneumo), moraxella, aerobic gram-, pneumocystis, legionella, listeria.
Chloramphenicol:Broad spectrum


Length of Administration
Use antibiotics for 3-4 days in: Use for 7-10 days in: Use for 10-14 days in: Use for 21 days in: Use for 28 days in: Use for 6 weeks in: