Antimicrobial susceptibility of clinical isolates of Haemophilus influenzae to ampicillin-sulbactam.
A total of 1092 clinical isolates of Haemophilus influenzae (306 type b; 786 non-type-b), from five medical centers were obtained during 1987 and 1988. Disk diffusion antimicrobial susceptibilities were obtained for all isolates, and broth microdilution susceptibilities were obtained for 502 isolates. Beta-lactamase was produced by 34.3% of type-b and 22.1% of non-type-b isolates, with some geographic variations. Using disk diffusion antimicrobial susceptibility testing, all isolates were susceptible to ampicillin-sulbactam, ceftriaxone, cefuroxime, and rifampin; two isolates were resistant to chloramphenicol. Whether tested using a fixed ratio of ampicillin to sulbactam of 2:1 or a fixed concentration of sulbactam, the ampicillin-sulbactam combination demonstrated good activity against clinical isolates of H. influenzae. Only 8 of the 1092 isolates did not produce beta-lactamase but demonstrated MICs of greater than or equal to 2 micrograms/ml for ampicillin.
Mortensen
J E
JE
Department of Laboratories, St. Christopher's Hospital for Children, Philadelphia, PA 19133.
LaRocco
M
M
Himes
S L
SL
Inderlied
C
C
Daly
J A
JA
Campos
J M
JM
Mendelman
P M
PM
D000667:Ampicillin / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology; D002444:Cefuroxime / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology; D004359:Drug Therapy, Combination / Q000494:pharmacology; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D008826:Microbial Sensitivity Tests; D015337:Multicenter Studies as Topic; D012293:Rifampin / Q000494:pharmacology; D013407:Sulbactam / Q000494:pharmacology*; D001618:beta-Lactamases / Q000096:biosynthesis
C035444:sultamicillin; D002701:Chloramphenicol; D002443:Ceftriaxone; D000667:Ampicillin; D001618:beta-Lactamases; D002444:Cefuroxime; D013407:Sulbactam; D012293:Rifampin