Genetic characteristics and antibiotic resistance of Haemophilus influenzae isolates from pediatric patients with acute otitis media after introduction of 13-valent pneumococcal conjugate vaccine in Japan.

Authors:
Kimiko Ubukata
Kimiko Ubukata
Kitasato University
Japan
Miyuki Morozumi
Miyuki Morozumi
Kitasato University
Japan
Megumi Sakuma
Megumi Sakuma
Kobe University
Japan
Yoko Adachi
Yoko Adachi
Kobe Central Hospital of Social Insurance
Eriko Mokuno
Eriko Mokuno
Hakujikai Memorial Hospital
Takeshi Tajima
Takeshi Tajima
Kitasato University
Japan
Satoshi Iwata
Satoshi Iwata
Kitasato University
Japan

J Infect Chemother 2019 Apr 12. Epub 2019 Apr 12.

Department of Infectious Diseases, National Cancer Center Hospital, Tokyo, Japan.

Acute otitis media (AOM) occurs commonly in pediatric populations. We examined resistance genotype, antibiotic susceptibility, quinolone (QL) resistance, and multilocus sequence type (MLST) among Haemophilus influenzae isolates causing AOM following introduction of pneumococcal conjugate vaccines in Japan. The AOM surveillance group included 69 participating otolaryngologists. Causative pathogens isolated from middle ear fluid (MEF) samples collected from 582 children with AOM were identified using both bacterial culture and real-time PCR. H. influenzae isolates among these pathogens were characterized by capsular type, resistance genotype, antibiotic susceptibility, QL resistance, and MLST. In 2016, H. influenzae was identified in 319 samples (54.8%), among which 72.4% (n = 231) tested positive by both culture and PCR; remaining H. influenzae cases were only PCR-positive. This proportion of H. influenzae positivity has increased significantly from 41.2% in 2006 (p < 0.001). Among culture-positive strains, genotypic β-lactamase-nonproducing ampicillin (AMP)-resistant (gBLNAR) strains were frequent (63.2%), with β-lactamase-nonproducing AMP-susceptible (gBLNAS) strains accounting for only 24.2%. Susceptibilities of gBLNAR to oral antimicrobials were best for tosufloxacin, followed by cefditoren and tebipenem; MICs were 0.031 μg/mL, 0.5 μg/mL, and 1 μg/mL, respectively. In 7 gBLNAR isolates (3.0%), QL susceptibility was low, owing to amino acid substitutions in GyrA and/or ParC. Sequence types identified numbered 107, including 28 that were new. Prevention of further increases in resistance to antimicrobial agents will require antibiotic selection based on characterization of causative pathogens in clinical practice.

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http://dx.doi.org/10.1016/j.jiac.2019.03.019DOI Listing
April 2019
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