Genetic and molecular characterization of beta-lactamase-negative ampicillin-resistant Haemophilus influenzae with unusually high resistance to ampicillin.

ABSTRACT: Previous studies with beta-lactamase-negative, ampicillin-resistant (BLNAR) Haemophilus influenzae from Japan, France, and North America indicate that mutations in ftsI encoding PBP3 confer ampicillin MICs of 1 to 4 micro g/ml. Several BLNAR strains with ampicillin MICs of 4 to 16 micro g/ml recently isolated from North America were studied. Pulsed-field gel electrophoresis identified 12 unique BLNAR strains; sequencing of their ftsI transpeptidase domains identified 1 group I and 11 group II mutants, as designated previously (K. Ubukata, Y. Shibasaki, K. Yamamoto, N. Chiba, K. Hasegawa, Y. Takeuchi, K. Sunakawa, M. Inoue, and M. Konno, Antimicrob. Agents Chemother. 45:1693-1699, 2001). Geometric mean ampicillin MICs for several clinical isolates were 8 to 10.56 micro g/ml. Replacement of

SUBMITTER: Kaczmarek FS 

PROVIDER: S-EPMC400547 | biostudies-literature | 2004 May

REPOSITORIES: biostudies-literature