Vol.57 No.1 January 2009

The prevalence of β-lactamase non-producing ampicillin-resistant Haemophilus influenzae(BLNAR) isolated from respiratory samples and investigation of the susceptibility trends in Nagasaki University Hospital from 2000 to 2006

Shigeki Nakamura¹⁾, Katsunori Yanagihara^1,2), Yoshitomo Morinaga^1,2), Takayoshi Kiya²⁾, Junichi Matsuda²⁾, Koichi Izumikawa¹⁾, Masafumi Seki¹⁾, Hiroshi Kakeya¹⁾, Yoshihiro Yamamoto¹⁾, Takayoshi Tashiro^1,3), Simeru Kamihira²⁾ and Shigeru Kohno¹⁾

¹⁾Second Department of Internal Medicine, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan
²⁾Department of Laboratory Medicine, Nagasaki University Hospital
³⁾School of Health Sciences, Nagasaki University Hospital

Abstract

The prevalence of strains with ampicillin(AMP) resistance among Haemophilus influenzae (H. influenzae) isolated from the lower respiratory tract has been increasing significantly during the 7 years from 2000, when it was 0%, to 2005, when it reached 29.7%. From 2006, the ratio of β-lactam resistant strains, which is β-lactamase non-producing AMP-resistant H. influenzae(BLNAR) strains with a minimum inhibitory concentration(MIC) of AMP of over 4 μg/mL and intermediate strains (MIC of AMP; 2 μg/mL), exceeded 50%. The prevalence of beta-lactamase positive strain has been decreasing from levels reported in previous studies to 1.8% in 2006. We measured the drug susceptibility test of BLNAR isolated from 2000-2006 to several currently approved antimicrobial agents. Piperacillin, ceftazidime, ceftriaxone had good potency, but the susceptibility of cefotiam, cefotaxime, cefepime were decreased. Meropenem and doripenem had good susceptibility, but imipenem and biapenem revealed low susceptibility. Azithromycin is the most effective drug in macrolides. All fluoroquinolones (levofloxacin, gatifloxacin, moxifloxacin) had good potency against H. influenzae, but one strain was levofloxacin low-susceptible (MIC=1.0 μg/mL). BLNAR has been increasing rapidly not only in pediatric but also respiratory tract medicine. It is important to realize the trends of drug resistant pathogens and effective antimicrobial agents, especially against BLNAR because there is difference of the drug susceptibility during the same groups.

Key word

adult community acquired pneumonia, Haemophilus influenzae, β-lactamase non-producing ampicillin resistant Haemophilus influenzae, drug resistance

Received

July 14, 2008

Accepted

October 21, 2008

Jpn. J. Chemother. 57 (1): 32-36, 2009