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empiric antibiotic therapy
Empiric antibiotic therapy for suspected infections when the organism(s) are unknown.
Indications:
1) intra-abdominal infection
2) urinary tract infection (UTI)
3) pneumonia
4) catheter-related sepsis (peripheral or central line)
5) endocarditis
6) meningitis
7) sepsis of unknown site
Management:
1) general principles
a) obtain blood cultures prior to initiating intravenous antibiotics
b) when gram stains, previous history, physical exam or laboratory information suggest a specific organism of known susceptibility, empiric therapy should be directed against that organism
c) initial therapy should be altered to target identified organisms
d) broad spectrum therapy is continued in febrile, neutropenic patients until neutropenia resolves
e) additional therapy other than antibiotics may be indicated
- surgical drainage for abscesses
- decongestants for sinusitis
2) intra-abdominal infection
a) peritonitis
- spontaneous bacterial peritonitis
- usual pathogens
- enteric gram negative rods
- Streptococcus sp including pneumococcus
- antibiotics
- 3rd generation cephalosporin
- ampicillin/gentamicin
- secondary peritonitis
- usual pathogens
- generally multiple organisms involved
- gram negative rods
- anaerobes
- Enterococci commonly found, but rarely pathogenic
- antibiotics
- cefotetan or ceftriaxone & metronidazole
- gentamicin & metronidazole
- add ciprofloxacin or amikacin if hospital-acquired
b) biliary tract infection
- usual pathogens
- gram negative rods
- Streptococcus sp
- anaerobes with previous surgery
- antibiotics
- cefazolin or ampicillin/gentamicin
- cefotetan or add metronidazole if history of biliary surgery
- ampicillin-sulbactam +/- aminoglycoside [2]
- piperacillin or mezlocillin + metronidazole +/- aminoglycoside [2]
c) pseudomembranous colitis
- usual pathogen: Clostridium difficile
- antibiotics
- oral metronidazole
- oral vancomycin
3) urinary tract infection (UTI)
a) suspect infection with resistant organism when:
- history of previous infection with resistant organisms
- patient has recently received antibiotics
- patients with indwelling catheters
- patients with multiple previous UTIs
- patients with spinal cord injury
b) community acquired UTI
- usual pathogens
- gram negative rods
- Enterococci
- antibiotics
- Bactrim DS
- ampicillin & gentamicin
c) nosocomial UTI or otherwise suspected resistant organism
- usual pathogens: gram negative rods
- antibiotics
- ceftazidime
- amikacin
- gentamicin
4) pneumonia
a) communitiy acquired
- usual pathogens
- Streptococcus pneumonia
- Haemophilus influenzae
- Legionella
- Mycoplasma
- antibiotics: cefuroxime or ceftizoxime plus erythromycin
b) nosocomial pneumonia & nursing home patients
- usual pathogens
- oral anaerobes (unless edentulous)
- gram negative rods
- Staphylococcus aureus
- antibiotics
- ceftazidime plus nafcillin plus metronidazole
- amikacin plus clindamycin
c) lung abscess
- usual pathogens: anaerobes (mixed)
- antibiotics: clindamycin
d) AIDS patient
- usual pathogens: Pneumocystis carinii
- antibiotics:
- Bactrim
- erythromycin (occasionally)
5) catheter-related sepsis (peripheral or central line)
a) usual pathogens
- Staphylococcus aureus
- Staphylococcus epidermidis
- gram negative rods
b) antibiotics
- vancomycin
- add ceftazidime or amikacin if patient is septic
6) endocarditis
a) subacute
- usual pathogens
- Streptococcus
- Enterococci
- antibiotics: ampicillin plus gentamicin
b) acute
- usual pathogens
- Streptococcus
- Staphylococcus aureus
- antibiotics: nafcillin plus gentamicin
c) prosthetic valve
- usual pathogens
- Streptococcus
- Staphylococcus aureus
- Staphylococcus epidermidis
- gram negative rods
- antibiotics: vancomycin plus gentamicin
7) meningitis
a) community acquired
- usual pathogens
- Streptococcus pneumonia
- Neisseria meningitidis
- antibiotics
- penicillin
- ampicillin
- ceftriaxone
b) post neurosurgery
- usual pathogens
- Staphylococcus aureus
- gram negative rods
- antibiotics: nafcillin plus ceftazidime
c) neutropenic host
- usual pathogens
- gram negative rods
- Listeria
- antibiotics: ceftazidime plus ampicillin
8) sepsis of unknown site
a) neutropenic host (< 1000 neutrophils/mm3)
- usual pathogens
- gram negative rods
- Staphylococcus aureus
- antibiotics:
- ceftazidime
- aminoglycoside & ceftazidime, ticarcillin, ticarcillin clavulanate, mezlocillin, piperacillin or imipenem [2]
- add vancomycin if central venous catheter
b) others
- usual pathogens
- Staphylococcus aureus
- gram negative rods
- antibiotics: ceftazidime plus nafcillin
Related
antibiotic (antimicrobial agent)
antibiotic prescribing practices; antibiotic overuse; outpatient parenteral antibiotics
General
antibiotic therapy
References
- R Libke, UCSF Fresno, 1998
- Medical Knowledge Self Assessment Program (MKSAP) 11, 16.
American College of Physicians, Philadelphia 1998, 2012
- Charani E et al.
Understanding the determinants of antimicrobial prescribing
within hospitals: The role of "prescribing etiquette.".
Clin Infect Dis 2013 Jul 15; 57:188
PMID: 23572483
http://cid.oxfordjournals.org/content/57/2/188?ijkey=7cf65eb4af31992aeb93e584e3af5075526f10a7&keytype2=tf_ipsecsha