Clonal spread of β-lactamase-producing amoxicillin–clavulanate-resistant (BLPACR) strains of non-typeable Haemophilus influenzae among young children attending a day care in Japan
Received 19 February 2010; received in revised form 30 April 2010; accepted 4 May 2010.
Abstract
Objective
Resistant strains of non-typeable Haemophilus influenzae (NTHi) are one of the principal causes of recurrent acute otitis media (otitis prone), rhinosinusitis, and pneumonia in young children. β-Lactamase-nonproducing ampicillin-resistant (BLNAR) strains are particularly common in Japan, and β-lactamase-producing amoxicillin–clavulanate resistant (BLPACR) strains are now emerging. We investigated the nasopharyngeal carriage status of these resistant strains among children attending a same day care center during a 10-year period.
Methods
From 1999 to 2008, we obtained nasopharyngeal swab specimens from young children attending a same day care center and examined the incidence of resistant strains of NTHi. Antimicrobial resistance of NTHi was identified based on PCR analysis of mutation of the penicillin binding protein (PBP) genes. Pulsed-field gel electrophoresis (PFGE) was performed to examine the clonal relationship of each resistant strain.
Results
The prevalence of resistant strains of NTHi among the children attending this day care has significantly increased during the past 10 years and most of this day care children recently have resistant strains with PBP gene mutations in their nasopharynx. Genetically BLPACR (gBLPACR) strains have rapidly increased since 2007 and PFGE analysis demonstrated that all gBLPACR were clonally identical. This is the first report of apparent clonal dissemination of gBLPACR strains of NTHi occurring in a certain environment such as day care.
Conclusions
The rapidly increasing prevalence of resistant strains, in particular gBLPACR, in this day care center may predict a high incidence of these resistant bacteria from clinical isolates in the near future and potential serious medical problems worldwide.
aDepartment of Otolaryngology-Head and Neck Surgery, Kanazawa University Graduate School of Medical Science, 13-1 Takaramachi, Kanazawa 920-8640, Japan
bDepartment of Otolaryngology-Head and Neck Surgery, Wakayama Prefectural Medical School, Wakayama, Japan
cDepartment of Otolaryngology, Kurobe Civic Hospital, Kurobe, Japan
ABSTRACT