Oxacillin

General

• Type: Anti-Staphylococcal Penicillin
• Dosage Forms: IM; IV
• Common Trade Names:

Adult Dosing

General

• Mild-to-moderate infection
  • 250-500mg IM/IV q4-6 hours
• Severe infection
  • 1g IM/IV q4-6 hours

Endocarditis

• 2g IV q4 hours + gentamicin

Prosthetic Joint Infection

• 2g IV q4 hours + rifampin

MSSA

• 2g IV q4 hours
• Examples: brain abscess, bursitis, erysipelas, mastitis, mastoiditis, osteomyelitis, perinephric abscess, pneumonia, pyomyositis, Scalded Skin Syndrome, Toxic Shock Syndrome

Pediatric Dosing

General

• Mild-to-moderate
  • 50mg/kg/day IM/IV divided q6 hours
  • First Dose: 12.5mg/kg IM/IV x 1
  • Max: 4 g/day
• Severe
  • 100mg/kg/day IM/IV divided q4-6 hours
  • First Dose: 16.6-25mg/kg IM/IV x 1
  • Max: 12 g/day

Community-Acquired Pneumonia (>3 Months)

• 150-200mg/kg/day divided q6-8 hours
• First Dose: 37.5-66.6mg/kg IV x 1
• For MSSA

Special Populations

• Pregnancy Rating: B
• Lactation: Use caution
• Renal Dosing
  • Adult: No adjustment
  • Pediatric:
    • CrCl <10: Use lower end of dosing range
• Hepatic Dosing
  • Adult: Not defined
  • Pediatric: Not defined

Contraindications

• Allergy to class/drug
• Caution:
  • Non-anaphylactic hypersensitivity to beta-lactams
  • Hypersensitivity to corn
  • Asthma
  • Recent abx-associated colitis
  • Renal impairment
  • Sodium restriction
  • Seizure disorder

Adverse Reactions

Serious

• Fever
• Rash
• Nausea and Vomiting
• Diarrhea
• Eosinophilia
• Leukopenia
• Neutropenia
• Thrombocytopenia
• Agranulocytosis
• Hepatotoxicity
• AST increased
• Acute interstitial nephritis
• Hematuria
• Serum sickness-like reactions

Pharmacology

• Half-life: 20-60 minutes (prolonged in neonates and renal impairment)
• Metabolism: Liver 45%; active metabolite
• Excretion: Urine (55-60% unchanged), Bile 10%
• Mechanism of Action: Bactericidal; inhibits cell wall mucopeptide synthesis

Antibiotic Sensitivities

Group	Organism	Sensitivity
Gram Positive	Strep. Group A, B, C, G	S
	Strep. Pneumoniae	S
	Viridans strep	I
	Strep. anginosus gp	S
	Enterococcus faecalis	R
	Enterococcus faecium	R
	MSSA	S
	MRSA	R
	CA-MRSA	R
	Staph. Epidermidis	S
	C. jeikeium	R
	L. monocytogenes	R
Gram Negatives	N. gonorrhoeae	R
	N. meningitidis	R
	Moraxella catarrhalis	R
	H. influenzae	R
	E. coli	R
	Klebsiella sp	R
	E. coli/Klebsiella ESBL+	R
	E coli/Klebsiella KPC+	R
	Enterobacter sp, AmpC neg	R
	Enterobacter sp, AmpC pos	R
	Serratia sp	R
	Serratia marcescens	X1
	Salmonella sp	R
	Shigella sp	R
	Proteus mirabilis	R
	Proteus vulgaris	R
	Providencia sp.	R
	Morganella sp.	R
	Citrobacter freundii	R
	Citrobacter diversus	R
	Citrobacter sp.	R
	Aeromonas sp	R
	Acinetobacter sp.	R
	Pseudomonas aeruginosa	R
	Burkholderia cepacia	R
	Stenotrophomonas maltophilia	R
	Yersinia enterocolitica	R
	Francisella tularensis	X1
	Brucella sp.	X1
	Legionella sp.	R
	Pasteurella multocida	R
	Haemophilus ducreyi	X1
	Vibrio vulnificus	X1
Misc	Chlamydophila sp	R
	Mycoplasm pneumoniae	R
	Rickettsia sp	X1
	Mycobacterium avium	X1
Anaerobes	Actinomyces	R
	Bacteroides fragilis	R
	Prevotella melaninogenica	R
	Clostridium difficile	X1
	Clostridium (not difficile)	X1
	Fusobacterium necrophorum	X1
	Peptostreptococcus sp.	S

Key

• S susceptible/sensitive (usually)
• I intermediate (variably susceptible/resistant)
• R resistant (or not effective clinically)
• S+ synergistic with cell wall antibiotics
• U sensitive for UTI only (non systemic infection)
• X1 no data
• X2 active in vitro, but not used clinically
• X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
• X4 active in vitro, but not clinically effective for strep pneumonia

See Also

• Antibiotics