Abstract
This study evaluated the microbiologic efficacy of ampicillin and ampicillin/sulbactam against microorganisms isolated most frequently from patients seen in general practice and in the hospital. A total of 3500 isolates (1400 from outpatients and 2100 from inpatients) were investigated. Beta-lactamase-producing isolates were encountered in 64% of
Escherichia coli, 43% of
Proteus species, and in 16% of
Haemophilus influenzae, regardless of whether they were obtained from community or hospitalized patients. The incidence of beta-lactamase production by
Klebsiella species among inpatients was strikingly different from that of outpatients (83% vs 59%). More than 93% of the tested gram-negative clinical isolates were susceptible to the combination of ampicillin/sulbactam, compared with only 50%–60% of isolates susceptible to ampicillin alone. The addition of sulbactam enhanced the activity of ampicillin against beta-lactamase-producing gram-positive strains. Thus 89% of beta-lactamase-positive strains of
Staphylococcus aureus and 85% of
Staphylococcus epidermidis are susceptible to the combination. In general practice, where beta-lactamase production has restricted the effectiveness of ampicillin, the combination of ampicillin with sulbactam has clearly extended the usefulness of ampicillin and has proven to be a first-line antibacterial agent.