Ampicillin/Sulbactam

General

• Type: Amino-Penicillins
• Dosage Forms: IM, IV
• Common Trade Names: Unasyn

Adult Dosing

General

• 1.5-3g IV/IM q6 hours
• Max: 12g/day

Bite (for Pasteurella multocida Coverage)

• 1.5-3g IM/IV q6 hours

Orbital Cellulitis

• 3g IM/IV q6 hours

Diabetic Foot Osteomyelitis

• 3g IM/IV q6 hours

PID

• 3g IM/IV q6 hours + doxycycline

Pneumonia

• Aspiration or CAP
  • 1.5-3g IM/IV q6 hours
• Hospital-acquired: 3g IM/IV q6 hours

UTI, Pyelonephritis

• 3g IM/IV q6 hours x 14 days

Pediatric Dosing (<40kg)

Unasyn (ampicillin/sulbactam) is formulated at a 2:1 ratio (3g vial = 2g ampicillin + 1g sulbactam)

General

• Mild-moderate
  • 100-200mg ampicillin/kg/day IM/IV divided q6 hours
  • First Dose: 25-50mg ampicillin/kg IM/IV x 1 (37.5-75mg Unasyn/kg IM/IV x 1)
  • Max: 1000mg ampicillin (1500mg Unasyn)
• Severe
  • 200mg ampicillin/kg/day IM/IV divided q6 hours
  • First Dose: 50mg ampicillin/kg IM/IV x 1 (75mg Unasyn/kg IM/IV x 1)
  • Max: 2000mg ampicillin (3000mg Unasyn)

Meningitis

• 400mg ampicillin/kg/day IM/IV divided q6 hours
• First Dose: 100mg ampicillin/kg IM/IV x 1 (150mg Unasyn/kg IM/IV x 1)
• Max: 2000mg ampicillin (3000mg Unasyn)

Endocarditis

• 200mg ampicillin/kg/day IM/IV divided q4-6 hours +/- gentamicin x 4-6 weeks

SSTI

• 200mg ampicillin/kg/day IM/IV divided q6 hours

Special Populations

• Pregnancy: B
• Lactation: Use caution
• Renal Dosing
  • Adult
  • Pediatric
• Hepatic Dosing
  • Adult
  • Pediatric

Contraindications

• Allergy to class/drug

Adverse Reactions

Serious

• Anaphylaxis

Common

• Headache
• Itching
• Nausea
• Vomiting

Pharmacology

• Half-life: One hour
• Metabolism:
• Excretion: Renal (75% excreted in active form), Bile (very small amount)
• Mechanism of Action: Bactericidal (Binds to penicillin-binding proteins to block cell wall synthesis), coupled with β-lacatamase inhibitor

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	S
	Enterococcus faecium	S
	MSSA	S
	MRSA	R
	CA-MRSA	R
	Staph. Epidermidis	R
	C. jeikeium	R
	L. monocytogenes	S
Gram Negatives	N. gonorrhoeae	S
	N. meningitidis	S
	Moraxella catarrhalis	S
	H. influenzae	S
	E. coli	S
	Klebsiella sp	S
	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	S
	Shigella sp	S
	Proteus mirabilis	S
	Proteus vulgaris	S
	Providencia sp.	S
	Morganella sp.	S
	Citrobacter freundii	R
	Citrobacter diversus	R
	Citrobacter sp.	R
	Aeromonas sp	S
	Acinetobacter sp.	S
	Pseudomonas aeruginosa	R
	Burkholderia cepacia	R
	Stenotrophomonas maltophilia	R
	Yersinia enterocolitica	I
	Francisella tularensis	X1
	Brucella sp.	X1
	Legionella sp.	R
	Pasteurella multocida	S
	Haemophilus ducreyi	S
	Vibrio vulnificus	X1
Misc	Chlamydophila sp	R
	Mycoplasm pneumoniae	R
	Rickettsia sp	X1
	Mycobacterium avium	X1
Anaerobes	Actinomyces	S
	Bacteroides fragilis	S
	Prevotella melaninogenica	S
	Clostridium difficile	X2
	Clostridium (not difficile)	S
	Fusobacterium necrophorum	S
	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 (Main)

Source

Authors

Ross Donaldson