Antibiotic resistance among clinical isolates of Haemophilus influenzae in the United States in 1994 and 1995 and detection of beta-lactamase-positive strains resistant to amoxicillin-clavulanate: results of a national multicenter surveillance study

• DOI: 10.1128/aac.41.2.292
• Publication Date: 2018-10-09T00:28:03Z
• Authors: G V Doern; A B Brueggemann; G Pierce; H P Holley; A Rauch
• Keywords: Cefpodoxime; Cefuroxime; Cefixime; Trimethoprim; Cefaclor

A total of 1,537 clinical isolates Haemophilus influenzae were recovered in 30 U.S. medical center laboratories between 1 November 1994 and April 1995 characterized a central laboratory with respect to serotype beta-lactamase production the vitro activities 15 oral antimicrobial agents. Overall, 36.4% found produce beta-lactamase. The rank order activity six cephalosporins on basis MICs was cefixime > cefpodoxime cefuroxime loracarbef or = cefaclor cefprozil. On current National Committee for Clinical Laboratory Standards (NCCLS) breakpoints ages be resistant intermediate these agents as follows: 0.1, 0.3, 6.4, 16.3, 18.3, 29.8, respectively (National Standards. Methods dilution susceptibility tests bacteria that grow aerobically, 4th ed. M7-A4, 1995). Azithromycin was, weight basis, most potent macrolides tested this study, followed by erythromycin then clarithromycin. typically fourfold more active than erythromycin, which turn, slightly However, when compared frequency resistance determined using NCCLS breakpoints, there essentially no difference azithromycin clarithromycin, i.e., 0.5 1.9%, (P 0.086). Interpretive MIC versus H. have not been developed. Resistance other non- beta-lactam variable, trimethoprim-sulfamethoxazole, 9.0%; chloramphenicol, 0.2%; tetracycline, 1.3%; rifampin, 0.3%. Two conspicuous findings study identification 39 strains negative but ampicillin (BLNAR) and, even surprisingly, 17 beta-lactamase-positive amoxicillin-clavulanate (BLPACR). Strains first group heretofore very uncommon; organisms second previously described literature. percentages all comprised BLNAR BLPACR 2.5 1.1, respectively. Overall thus 38.9%, 4.5%.