Make your own free website on Tripod.com

GUIDELINES ON ANTIBIOTIC SELECTION

Treatment Recommendations for Common Infections

DiseaseLikely MicrobiologyTherapy Comments
1Pneumonia
A.Community acquired
  • Unknown


  • Influenza A


  • Mycoplasma or Chlamydia



  • Legionella
  • Ceftriaxone or ceftizoxime

  • Ceftriaxone or ceftizoxime plus Amantidine or rimantidine

  • Ceftriaxone or ceftizoxime plus Erythromycin or azithromycin

  • Ceftriaxone or ceftizoxime plus Erythromycin
  • If cephalosporin allergic, substitute erythromycin or clarithromycin








  • Substitute azithromycin if erythromycin not tolerated
  • Aspiration
  • Ceftriaxone or ceftizoxime plus Clindamycin or
  • Piperacillin/tazobactam or ampicillin/sulbactam
  • Aspiration prone (sedation, stroke, LOC)
  • Anaerobes, gram-positive organisms
  • Clindamycin or
  • Ampicillin/sulbactam
  • May consider adding cefuroxime if gram-negative aerobes are of a concern
  • B.Hospital acquired (including aspiration)
  • Gram-negatives: E. coli, Enterobacter, Pseudomonas, Klebsiella



  • Staphylococcus aureus
  • Ticarcillin/clavulanate plus Tobramycin or
  • Clindamycin plus Cipropfloxacin or Ceftazidime or
  • Imipenem +/- Aminoglycoside

  • Nafcillin
  • 60% of nosocomial pneumonias are gram-negative in origin, 15% staph




  • If MRSA suspected, add Vancomycin
  • 2Fungal Infections
  • Blastomycosis
  • Itraconazole (nonlife threatening, non-meningeal)
  • Amphotericin B
  • Itraconazole requires acid pH for absorption. Avoid antacids, H2 blockers
  • Amphotericin should be reserved for life threatening or CNS disease
  • Histoplasmosis
  • Itraconazole (nonlife-threatening, non-meningeal)
  • Amphotericin B
  • Amphotericin B is indicated for meningeal infections
  • Cryptococcus
  • Amphotericin B 5-Flucytocine
  • Amphotericin is the agent of choice for rapidly progressing life-threatening disease
  • Fluconazole is used for chronic suppression in HIV related disease
  • Candida albicans
    superficial/mucosal
  • Fluconazole
  • Miconazole
  • Clotrimazole
  • Ketoconazole
  • For candida esophagitis, fluconazole is preferred agent
  • Candida albicans
    Deep seated, disseminated
  • Amphotericin B
  • Fluconazole
  • Amphotericin is the agent of choice for rapidly progressing life-threatening disease
  • Prophylaxis with fluconazole in high risk populations is experimental, and should be limited to short courses
  • Deep seated, disseminated non-albicans candidiasis
    (Torulopsis glabrata, Candida krusei)
  • Amphotericin B
  • Fluconazole has relatively poor activity against these species
  • Candida lusetaniae
  • Fluconazole
  • Resistant to Amphotericin
  • 3Gastrointestinal
    A.Cholecystitis
  • Coliforms and enterococci
  • Cefotetan
  • Pipercillin/tazobactam (or ampicillin/sulbactam) + Gentamicin
  • Cefotetan should be reserved for mild to moderate infections
  • B.Cholangitis
  • Enterics
  • Enterococci
  • Anaerobes
  • Pipercillin/tazobactam (or ampicillin/sulbactam) + Gentamicin
  • C.Diverticulitis
  • Enterics
  • Anaerobes
  • Cefotetan
  • Clindamycin + Cipropfloxacin (or Ceftazidime)
  • Pipercillin/tazobactam (or ampicillin/sulbactam) + Gentamicin
  • Cefotetan should be reserved for mild to moderate infections
  • D.Intra-abdominal peritonitis or abscess
  • Enterics
  • Anaerobes
  • Enterococci
  • Pipercillin/tazobactam (or ampicillin/sulbactam) + Gentamicin
  • Clindamycin + Cipropfloxacin (or Ceftazidime)
  • Ceftizoxime
  • Imipenem
  • The gram-negative activity of ampicillin/sulbactam/Gentamicin may be less than that of the other combinations listed
  • 4Genitourinary
    A.Cystitis
  • E. coli
  • Staphylococcus saprophyticus
  • TMP/SMX
  • Cephalexin
  • Nitrofurantoin
  • Three day course; may resolve spontaneously without therapy.
  • B.Pyelonephritis
  • Oral therapy for mild disease is appropriate
  • Community (no underlying GU disease)
  • E. coli, Proteus
  • TMP/SMX
  • Aminoglycosides
  • Ceftriaxone
  • Ciprofloxacin (oral)
  • Enterococcus is an uncommon pathogen and can be identified on gram stain
  • Nosocomial (underlying GU disease)
  • Other gram-negatives including:
  • E. coli
  • Pseudomonas
  • Enterococcus
  • Ampicillin + gentamicin or tobramycin
  • Piperacillin/tazobactam + Tobramycin
  • Ciprofloxacin ampicillin
  • These drug combinations are for empiric coverage for Pseudomonas and Enterococcus
  • Patients who are septic require double gram-negative coverage
  • C.Prostatitis
    a.Acute
    Age<35 y/o
  • Neisseria gonorrhea
  • Chlamydia
  • Ceftriaxone 125 mg IM in a single dose or Ciprofloxacin 500 mg po in a single dose
  • plus Doxycycline 100 mg po bid X 7 days
  • Age>35 y/o
  • Enterobacteraciae
  • TMP/SMX
  • Ciprofloxacin
  • b.Chronic
  • Enterobacteraciae
  • Enterococcus
  • TMP/SMX X 3 mos or
  • Ciprofloxacin X 4 wks
  • If treatment failure, rule out prostatic calculi
  • 5Skin/Soft tissue
    A.Cellulitis (non-diabetic)
  • Streptococcus
  • Staphylococcus
  • Nafcillin (oral dicloxacilin)
  • Clindamycin or cefazolin in non-anaphylactic penicillin allergy
  • For known Streptococcal infection, penicillin G is drug of choice
  • B.Decubitus ulcer / Diabetic ulcer
  • Staphylococcus
  • Streptococcus
  • Gram-negatives
  • Anaerobes
  • Amoxicillin/clavulate (po) or ampicillin/sulbactam (IV)
  • Clindamycin + Cipropfloxacin (or Ceftazidime)
  • Ceftizoxime
  • Piperacillin/tazobactam Tobramycin
  • Amoxicillin/clavulate or ampicillin/sulbactam does not cover Pseudomonas
  • Surgical consultation should be part of routine management
  • C.Necrotizing fasciitis
  • Streptococcus
  • Staphylococcus
  • Gram-negative aerobes
  • Anaerobes
  • Penicillin + Clindamycin + Aminoglycoside (or Ciprofloxacin)
  • Ampicillin/sulbactam + Aminoglycoside (or Ciprofloxacin)
  • Imipenem
  • Necrotizing fasciitis may be due to mixed flora, including anaerobes (clostridia perfringens). Broad spectrum coverage may be required.
  • Primary emphasis is on surgical treatment
  • D.Human/animal bites
  • Pasteurella multocida
  • Streptococcus
  • Staphylococcus
  • Ampicillin/sulbactam IV/ or amoxicillin/clavulate po
  • Spectrum includes Pasteurella multocida, especially in cat bites
  • Do not use oral first-generation cephalosporins for Pasteurella
  • 6Bone & Joint
    A.Osteomyelitis
    a.Acute (hematogenous)
  • Staphylococcus aureus
  • Gram-negatives (less frequent)
  • Nafcillin Aminoglycoside
  • Establish bacteriology with appropriate cultures
  • Gram (-) osteomyelitis may occur in the setting of underlying GI or GU tract infection
  • Ceftriaxone may allow outpatient parenteral therapy
  • Cefazolin or clindamycin may be options for PCN allergic pts
  • b.Diabetic foot or contiguous ulcer
  • Gram-negatives
  • Gram-positives
  • Anaerobes
  • Ciprofloxacin (po) + Clindamycin or Piperacillin/tazobactam or
  • Ampicillin/sulbactam + Aminoglycoside
  • Establish bacteriology with appropriate cultures whenever possible
  • Adequate surgical debridement is critical to overall success
  • c.Chronic osteomyelitis
  • See comments
  • Establishing microbiology is primary
  • B.Septic Arthritis
    a.Sexually active young adult
  • Gonococcus
  • Ceftriaxone 125 mg IM in a single dose or Ciprofloxacin 500 mg po in a single dose plus Doxycycline 100 mg po bid X 7 days
  • b.Adult
  • Staphylococcus aureus
  • Group A Streptococcus
  • Gram-negative aerobes
  • Nafcillin + gentamicin or
  • Nafcillin + po ciprofloxacin
  • Microbiology needed
  • Orthopedic consultation required
  • c.With prosthesis
  • Staphylococcus epidermidis
  • Staphylococcus aureus
  • Gram-negatives
  • Vancomycin + 3rd generation cephalosporin
  • Orthopedic consultation required
  • 7CNS Infections
    A.Meningitis
    a.Community
    Age18-50
  • Streptococcal pneumonia
  • N. meningitis
  • Haemophilus influenza (1-3%)
  • Cefotaxime
  • 3rd generation cephalosporins are empiric drug of choice due to concerns of moderately resistant pneumococcus
  • (Penicillin may be used if organism is penicillin-sensitive)
  • Antimicrobial therapy should be initiated within 30-60 min of presentation
  • Penicillin-allergic patients should receive chloramphenicol
  • b.Age >50 or Alcoholic or Debilitated medical condition
  • Gram-negative aerobes
  • Strep.pneumoniae
  • Listeria
  • Ampicillin + ceftriaxone
  • c.Post neurosurgery
  • Staphylococcus epideridis
  • MRSA
  • Gram-negative aerobes
  • Vancomycin & Ceftazidime
  • Infection related to catheters may require removal
  • d.Immunosuppressed
  • Community acquired pathogens
  • Listeria monocytogenes
  • Fungal
  • Mycobacterial
  • Ampicillin + ceftriaxone
  • Initial gram stain may provide clues for likely microbiology
  • Need to rule out cryptococcus or other opportunistic infections
  • B.Encephalitis
    Viral encephalitis/ Meningioencephalitis
    Viral encephalitis
  • Herpes simplex
  • Enteroviruses
  • Coxsackie
  • Acyclovir
  • No therapy
  • No therapy
  • Early initiation of acyclovir is important for all patients suspected to have viral encephalitis
  • Bacterial cerebritis expected if contiguous focus, ie., mastoiditis, sinusitis, otitis media
  • Legionella or mycoplasma may present with encephalopathy
  • Encephalitis in immunosuppressed host
  • Herpes Simplex
  • Enteroviruses
  • Coxsackie
  • Cryptococcus
  • Toxoplasmosis
  • Listeria
  • Acyclovir
  • No therapy
  • No therapy
  • Amphotericin B
  • Pyrimethamine + sulfadiazine
  • Ampicillin
  • Need to make specific diagnosis to rule out cryptococcus or toxoplasmosis before empiric therapy.
  • C.Brain Abscess
    a.Otogenic(temporal, parietal, cerebellar)
  • Strep. species
    Anaerobes
    Enterobacteraciae
  • Ceftriaxone & metronidazole +/- Penicillin G
  • If endocarditis suspected, nafcillin should be added instead of Pen G for Staph. aureus
    b.Paranasal (frontal)
  • Enterobacteraciae
  • 8Head and Neck
    A.Sinusitis
    Acute
  • Strep. pneumoniae
  • H. flu
  • Moraxella catarrhalis
  • TMP/SMX
  • Cefpodoxime
  • Amoxicillin/clavulate
  • Need to consider fungal etiology in neutropenic, transplant, or IDDM patients
  • Chronic
  • Above plus anaerobes plus staph
  • Amoxicillin/clavulate
  • Chronic sinusitis requires surgical drainage
  • Hospital-acquired
  • Gram-negative aerobes
  • Staph. aureus
  • Anaerobes
  • See pneumonia treatment
  • Nasotracheal intubation and nasogastric tubes may increase risk of hospital-acquired sinusitis
  • B.Pharyngitis
    Exudative
  • Group A strep
  • Penicillin G
  • Mononucleosis may present with exudative pharyngitis
  • Vesicular/Ulcerative
  • Coxsackie, echo, or Herpes simplex virus
  • Acyclovir (herpes simplex only)
  • Membraneous
  • Mononucleosis
  • Diphtheriae
  • No treatment
  • Erythromycin
  • Endotracheal intubation for maintenance of airway
  • Steroids for impending airway obstruction
  • C.Epiglottitis
  • Group A Strep. or H. flu
  • Cefuroxime or ceftriaxone
  • Early elective endotracheal intubation
  • D.Periorbital/Orbital Cellulitis
  • Streptococcus species
  • Staphylococcus
  • Haemophilus influenza (adults)
  • Anaerobes (if related to dental procedures)
  • Cefuroxime
  • Ampicillin/sulbactam
  • R/O dental or sinus focus
  • If immunosuppressed, fungal etiology must be considered
  • E.Otitis media
  • See acute sinusitis
  • See acute sinusitis
  • Consider ENT pathology in adults with recurrent otitis media
  • F.Mastoiditis
    Acute
  • Strep. pneumoniae
  • Strep. pyrogenes
  • Staph. aureus
  • Dicloxacillin
  • Cefuroxime
  • Surgery for abscess or osteomyelitis
  • Chronic
  • Polymicrobial, including Pseudomonas
  • Staph.aureus and anaerobes
  • Ceftazidime + Clindamycin
  • Tobramycin + Ticarcillin/clavulate
  • Surgery is required
  • 9Sexually Transmitted Diseases (STD )
    A.Urethritis
    Cervicitis
    Prostatitis
  • N. gonorrhaeae
  • Chlamydia
  • Ceftriaxone 125 mg IM in a single dose or Ciprofloxacin 500 mg po in a single dose
  • plus Doxycycline 100 mg po bid X 7 days
  • Disseminated N. gonorrhaeae
  • Ceftriaxone 1 gm X 24-48h then switch to ciprofloxacin for 7 days
  • B.PID
  • Gonococcus
  • Chlamydia
  • Bacteroides
  • Enteric gram-negatives
  • Outpatient - Ceftriaxone 250 mg IM + doxycycline po bid X 14 days
  • Inpatient - Cefotetan 2 gm q 12 IV + doxycycline bid X 14 days
  • Candidates for outpatient: temp < 38 degrees C, WBC < 11,000, no indication of peritonitis
  • C.Genital lesions
    a.Herpes Simplex
  • HSV
  • Acyclovir
  • b.Chancroid
  • Hemophilus ducreyi
  • Ceftriaxone 250 mg IM single dose or
  • Erythromycin 500 mg qd X 7 days or
  • Azithromycin 1 gm orally X 1 single dose
  • c.Lymphogranuloma venereum
  • Chlamydia
  • Doxycycline 100 mg bid X 21 days
  • Rare disease in USA
  • d.Syphillis
  • HIV patients and pregnant patients with syphilis should have infectious disease consults
  • Primary
    Secondary
    Latent <1 yr
  • Treponema pallidum
  • Benzathine PCN single dose 2.4 mu IM
  • Latent >1 yr or
    unknown duration
  • Benzathine PCN 2.4 mu IM X 3 doses
  • e.Neurosyphilis
  • Penicillin G 12-24 mu qd X 10-14 days (2-4 mu q 4 hr)
  • last update 10/17/98