[Trends in antibiotic susceptibility and genetic beta-lactam resistance patterns among Haemophilus influenzae cases isolated from adult patients with respiratory tract infection].
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.
Hagiwara
Eri
E
Department of Respiratory Medicine, Kanagawa Cardiovascular and Respiratory Center.
Watanuki
Yuji
Y
Shiihara
Jun
J
Matsushima
Atsushi
A
Enomoto
Takahiro
T
Sekine
Akimasa
A
Tsuchiya
Noriko
N
Baba
Tomohisa
T
Shinohara
Takeshi
T
Endo
Takahiro
T
Sogo
Yoko
Y
Nishihira
Ryuichi
R
Komatsu
Shigeru
S
Kato
Terufumi
T
Ogura
Takashi
T
Takahashi
Hiroshi
H
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*
D046915:Penicillin-Binding Proteins; D001618:beta-Lactamases