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Published on: May 2, 2018
β-Lactamase-non-producing ampicillin-resistant Haemophilus influenzae is acquiring multidrug resistance
Shogo Yamada1, Shoji Seyama1, Takeaki Wajima1
1Department of Microbiology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 1920392, Japan.
Background:
Haemophilus influenzae strains with reduced susceptibilities to antimicrobial agents have emerged in Japan. Here, we aimed to investigate H. influenzae non-susceptibility to β-lactams and non-β-lactams.
Methods:
A total of 260 H. influenzae isolates from patients in 2013-2016 were analysed. Antimicrobial susceptibilities were assessed by determining the minimum inhibitory concentration. Additionally, isolates with reduced susceptibility were analysed by both genetic and statistical methods.
Results:
β-Lactamase-non-producing ampicillin-resistant H. influenzae (BLNAR) strains increased significantly and accounted for more than 50% of all isolates from 2014. Additionally, the proportion of quinolone-low-susceptibility isolates increased significantly (P<0.05). Among these, three quinolone-non-susceptible isolates showed minimum inhibitory concentrations higher than the susceptibility breakpoint of levofloxacin. Moreover, one of the three isolates showing multidrug resistance was resistant to macrolides, β-lactams, and quinolones. Low susceptibilities to non-β-lactams were significantly associated with BLNAR.
Conclusions:
The present study indicates that BLNAR strains are increasing and tend to show multidrug resistance. Additionally, multidrug-resistant H. influenzae (MDRHI) has emerged. To prevent the further spread of MDRHI, the proportions of BLNAR strains should be evaluated.
Insights
Antimicrobial resistance in Haemophilus influenzae is rising in Japan. Beta-lactamase-non-producing ampicillin-resistant H. influenzae (BLNAR) strains are increasing and show multidrug resistance, indicating a need for monitoring.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Emergence of antimicrobial-resistant Haemophilus influenzae strains in Japan.
- Need to investigate H. influenzae non-susceptibility to beta-lactams and non-beta-lactams.
Purpose of the Study:
- To investigate the prevalence and characteristics of H. influenzae non-susceptibility to beta-lactams and non-beta-lactams.
- To identify trends in antimicrobial resistance patterns.
Main Methods:
- Analysis of 260 H. influenzae isolates from 2013-2016.
- Antimicrobial susceptibility testing using minimum inhibitory concentration (MIC).
- Genetic and statistical analysis of resistant isolates.
Main Results:
- Significant increase in beta-lactamase-non-producing ampicillin-resistant H. influenzae (BLNAR) strains, exceeding 50% of isolates by 2014.
- Significant rise in quinolone-low-susceptibility isolates (P<0.05).
- Identification of multidrug-resistant H. influenzae (MDRHI) isolates exhibiting resistance to multiple antibiotic classes, including beta-lactams, quinolones, and macrolides. Low non-beta-lactam susceptibility associated with BLNAR.
Conclusions:
- BLNAR strains are increasing and demonstrate a tendency towards multidrug resistance.
- Emergence of multidrug-resistant H. influenzae (MDRHI) in Japan.
- Importance of monitoring BLNAR strain proportions to prevent the spread of MDRHI.
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