Abstract
In a multicenter survey, 2100 strains of bacteria isolated from clinical specimens from hospitalized patients were examined for production of beta-lactamase and susceptibility to commonly prescribed antibiotics. Bacteria tested consisted of 1050 strains of Enterobacteriaceae, 150 strains of
Haemophilus influenzae, and 900 strains of staphylococci. Among the Enterobacteriaceae tested, 83% of
Klebsiella species, 64% of
Escherichia coli, and 43% of
Proteus species produced beta-lactamase. Only 15% of
H influenzae were beta-lactamase producers. Of the staphylococci, 89% of
Staphylococcus aureus and 85% of
Staphylococcus epidermidis were beta-lactamase positive. The susceptibility of the isolates to various antibiotics was determined using the agar dilution method. Cefuroxime and amoxicillin-clavulanate had greater in vitro activity against beta-lactamase-producing strains of staphylococci than did cephalexin, trimethoprim-sulfamethoxazole, or amoxicillin. Cefixime showed little activity against staphylococci. Ninety-nine percent of
H influenzae were sensitive to amoxicillin-clavulanate and cefuroxime, 83% were sensitive to amoxicillin, 84% to trimethoprim-sulfamethoxazole, and 62% to cephalexin. Resistance of
E coli isolates was 44% to tetracycline, 29% to trimethoprimsulfamethoxazole, and 18% to gentamicin. Nearly 92% of
E coli isolates were inhibited by cefuroxime and 94% by amoxicillin-clavulanate. The types of beta-lactamase produced by 333 random isolates were determined. Plasmid-mediated beta-lactamases were encountered in 93% of
E coli and 67% of
Klebsiella species. Almost all
H influenzae isolates (96.6%) produced the TEM1 enzyme. Changing patterns of susceptibility and the availability of new and expensive agents require continual updating of knowledge concerning treatment of these pathogens.