Ampicillin

Ampicillin - has a spectrum of activity, which includes staphylococci, streptococci, most enterococci, Listeria monocytogenes and Gram ve rods such as Salmonella spp., Shigella spp., E. coli, H. influenzae and Proteus spp. It is not active against Pseudomnas aeruginosa and Klebsiella spp. However due to acquired resistance almost all staphylococci, 50% of E. coli and up to 15% of H. influenzae strains are now resistant. All penicillin-resistant pneumococci and enterococci have reduced susceptibility to ampicillin. Amoxicillin is similar but better absorbed orally.

Uses
Urinary tract infections
Respiratory tract infections
Invasive salmonellosis
Serious infections with Listeria monocytogenes, including meningitis

Contraindications:
Penicillin hypersensitivity

Administration:
• IV: 500 mg–1 g diluted in 10 ml WFI, 4–6 hourly over 3–5 min
• Meningitis caused by Listeria monocytogenes (with gentamicin)
IV: 2 g diluted in 10 ml WFI every 4 hours over 3–5 minutes.Treat for 10–14 days

In renal impairment:

CC (ml/min)	Dose (g) (range depending on severity of infection)	Interval (h)
10–20	500 mg–2	6
<10	250 mg–1	6

How not to use ampicillin:
Not for intrathecal use (encephalopathy)
Do not mix in the same syringe with an aminoglycoside (efficacy of aminoglycoside reduced)

Adverse effects:
Hypersensitivity
Skin rash increases in patients with infectious mononucleosis (90%), chronic lymphocytic leukaemia and HIV infections (discontinue drug)

Cautions:
Severe renal impairment (reduce dose, rashes more common)

Renal replacement therapy:
CVVH dose as for CC 10–20 ml/min, i.e. 500 mg–2 g every 6 hours. Not significantly cleared by PD or HD, dose as if CC <10 ml/min, i.e. 250 mg–1 g every 6 hours