title: Increasing prevalence of ampicillin- resistant, non-beta-lactamase-producing strains of Haemophilus influenzae in children in Japan.
abstract: Among Haemophilus influenzae isolated from children with respiratory tract infections, the evolution of ampicillin resistance was investigated during 1996 and 1997 in Japan. beta-Lactamase production was assessed and minimum inhibitory concentrations (MICs) of eight antimicrobial agents were determined using a broth microdilution method in Mueller-Hinton-lysed horse blood medium. Of 74 H. influenzae, 11 strains (14.9%) produce beta-lactamase and were thus highly resistant to ampicillin (MIC of >4.0 microgram/ ml). In addition, moderate resistance to ampicillin, defined as an MIC of >==1.0 microgram/ml, was noted in 44.4% of all beta-lactamase-negative isolates. These beta-lactamase-negative ampicillin-resistant (BLNAR) organisms were resistant to other cephalosporins such as cefpodoxime and cefdinir, while beta-lactamase-producing strains were susceptible to them. Cefditoren, cefteram, and minocycline were active against all strains studied, whereas cefaclor and clarithromycin were inactive against all H. influenzae isolates in this study. Results indicate that BLNAR strains have emerged among children with respiratory tract infections in Japan.
authors.affiliation: Department of Nursing, School of Health Sciences, Faculty of Medicine, Kanazawa University, Kanazawa, Japan. hseki@mhs.mp.kanazawa-u.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Seki
authors.forename: Y
authors.initials: Y
authors.lastname: Kasahara
authors.forename: K
authors.initials: K
authors.lastname: Ohta
authors.forename: Y
authors.initials: Y
authors.lastname: Saikawa
authors.forename: R
authors.initials: R
authors.lastname: Sumita
authors.forename: A
authors.initials: A
authors.lastname: Yachie
authors.forename: S
authors.initials: S
authors.lastname: Fujita
authors.forename: S
authors.initials: S
authors.lastname: Koizumi
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D000668:Ampicillin Resistance; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D006801:Humans; D007564:Japan; D008297:Male; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology*; D001618:beta-Lactamases / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D000667:Ampicillin; D001618:beta-Lactamases