Related Experiment Video
Updated: May 29, 2025
One-day Workflow Scheme for Bacterial Pathogen Detection and Antimicrobial Resistance Testing from Blood Cultures
Published on: July 9, 2012
Longitudinal Trend in Antimicrobial Susceptibility among Haemophilus influenzae: A Single-Centre Study in Japan
Takeaki Wajima1, Naoki Hara2, Emi Tanaka1
1Department of Microbiology, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.
Abstract:
Haemophilus influenzae presents significant concerns regarding antimicrobial resistance. The circumstances surrounding H. influenzae have been changing owing to changes in antimicrobial usage. In the present study, to determine the current situation of H. influenzae, the antimicrobial susceptibility trends were investigated. In total, 21 clinical isolates were analyzed. Antimicrobial susceptibility measured using the broth dilution method was compared with that reported in previous studies at the same hospital. Quinolone low-susceptible isolates were further characterized by multi-locus sequence typing. Upon comparing the susceptibility data in 2022 with those in the past 15 years, the number of β-lactamase nonproducing ampicillin-resistant isolates was decreased. Regarding recent changes, β-lactam-susceptible isolates were found to have gradually increased every year. However, β-lactamase-producing isolates did not decrease. In particular, the ratio of β-lactamase-producing amoxicillin and clavulanic acid-resistant isolates in 2022 was the highest among all the years studied. Moreover, quinolone low-susceptible isolates were still present, suggesting that these isolates could have been indigenized in the community. Furthermore, a β-lactamase-producing amoxicillin and clavulanic acid-resistant isolate was found to have emerged among the quinolone low-susceptibility isolates. At first glance, these findings indicate that antimicrobial resistance has decreased among H. influenzae in clinical settings. However, β-lactamase-producing isolates and quinolone low-susceptible isolates have remained at a constant rate in the community.
Insights
Antimicrobial resistance in Haemophilus influenzae shows a decrease in some ampicillin-resistant strains but a concerning rise in beta-lactamase-producing and quinolone-resistant isolates, indicating persistent community threats.
Area of Science:
- Clinical microbiology
- Infectious diseases
- Antimicrobial resistance
Background:
- Haemophilus influenzae is a significant pathogen with evolving antimicrobial resistance patterns.
- Changes in antimicrobial usage influence the resistance landscape of H. influenzae.
- Understanding current susceptibility trends is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate the current antimicrobial susceptibility trends of Haemophilus influenzae.
- To compare recent susceptibility data with historical data from the past 15 years.
- To characterize quinolone-resistant isolates and identify emerging resistance mechanisms.
Main Methods:
- Analysis of 21 clinical isolates of Haemophilus influenzae.
- Broth dilution method for antimicrobial susceptibility testing.
- Multi-locus sequence typing for characterizing quinolone-resistant isolates.
Main Results:
- A decrease in beta-lactamase non-producing ampicillin-resistant isolates was observed.
- An increase in beta-lactam-susceptible isolates was noted annually.
- However, beta-lactamase-producing isolates did not decrease, with a record high of amoxicillin/clavulanic acid resistance in 2022.
- Quinolone low-susceptible isolates persist, suggesting community indigenization.
- A novel isolate resistant to amoxicillin/clavulanic acid and low-susceptible to quinolones emerged.
Conclusions:
- While some resistance markers have decreased in clinical settings, beta-lactamase-producing and quinolone-resistant H. influenzae strains remain prevalent.
- The emergence of dual-resistant isolates highlights the need for continued surveillance and novel therapeutic approaches.
- Sustained resistance in the community poses an ongoing challenge for public health.
