title: [Trends in antibiotic susceptibility and genetic beta-lactam resistance patterns among Haemophilus influenzae cases isolated from adult patients with respiratory tract infection].
abstract: Haemophilus influenzae, a major respiratory tract pathogen, is becoming increasingly resistant to beta-lactam antibiotics. Studying annual trends in antibiotic susceptibility and genetic patterns of H. influenzae beta-lactam resistance, we isolated 122 strains from the adult respiratory tract in 2007, determined MIC for different antibiotics, and analyzed TEM-1 beta-lactamase resistant genes and ftsI encoding PBP3 mutation compared to results in 2005 and 2007. We found that ABPC-susceptible strains with MIC <1 microg/mL (BLNAS) accounted for 71.0%, ABPC-resistant strains with MIC exceeding 2 microg/mL without beta-lactamase activity (BLNAR) for 25.3%, and beta-lactamase-positive strains (BLP) for 3.7%. The BLNAS ratio showed no significant change from 2002 and 2005. The BLP ratio decreased from those in 2002 and 2005. Genetic studies of resistant genes showed that gBLNAS with no resistant genes had increased in the last five years. The ratio of all strains with PBP3 mutation (gBLNAR and gLow-BLNAR) remained constant from 2002 to 2007. The proportion of gBLNAR with two PBP3 mutations had increased, however, while gLow-BLNAR with one mutation had decreased. LVFX showed constant strong antimicrobial potency for all mutation groups. Among beta-lactam antibiotics, the lowest MIC90 was observed in parenteral CTRX and oral CDTR-PI use. Although a new MIC peak generated by gBLNAR became obvious in the ABPC and CDTR-PI MIC distribution, the MIC of the new peak was still low enough to treat with high doses of those two antibiotics.
authors.affiliation: Department of Respiratory Medicine, Kanagawa Cardiovascular and Respiratory Center.
authors.forename: Eri
authors.initials: E
authors.lastname: Hagiwara
authors.forename: Yuji
authors.initials: Y
authors.lastname: Watanuki
authors.forename: Jun
authors.initials: J
authors.lastname: Shiihara
authors.forename: Atsushi
authors.initials: A
authors.lastname: Matsushima
authors.forename: Takahiro
authors.initials: T
authors.lastname: Enomoto
authors.forename: Akimasa
authors.initials: A
authors.lastname: Sekine
authors.forename: Noriko
authors.initials: N
authors.lastname: Tsuchiya
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Baba
authors.forename: Takeshi
authors.initials: T
authors.lastname: Shinohara
authors.forename: Takahiro
authors.initials: T
authors.lastname: Endo
authors.forename: Yoko
authors.initials: Y
authors.lastname: Sogo
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Nishihira
authors.forename: Shigeru
authors.initials: S
authors.lastname: Komatsu
authors.forename: Terufumi
authors.initials: T
authors.lastname: Kato
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D000328:Adult; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D010403:Penicillin Resistance / Q000235:genetics*; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D012141:Respiratory Tract Infections / Q000382:microbiology*; D001618:beta-Lactamases / Q000032:analysis*
chemical_list: D046915:Penicillin-Binding Proteins; D001618:beta-Lactamases