Article in Japanese

The state of drug susceptibility of Haemophilus influenzae isolated from pediatric patients with respiratory tract infections at our hospital and the background factors

Kurumi ABE^1,2), Mio ENDO^1,2), Shinya KAWANO^3,4), Koji MORITA^5,6), Katsumi MIZUNO^5,6), Toru WATANABE^1,2), Tadanori SASAKI²⁾

This study retrospectively investigated drug susceptibility to various antimicrobial agents of 56 strains of Haemophilus influenzae, which were isolated at this hospital from pediatric patients with respiratory tract infections between March 24 and November 30, 2014. It also investigated background factors, including age, siblings, attendance at daycare groups, and usage of previous antimicrobial agents.
Regarding the 56 strains of H. influenzae, the isolation frequency of β-lactamase-nonproducing ampicillin-susceptible H. influenzae (BLNAS), β-lactamase-nonproducing ampicillin-intermediately resistant H. influenzae (BLNAI), β-lactamase-nonproducing ampicillin-resistant H. influenzae (BLNAR), β-lactamase-producing ampicillin-resistant H. influenzae (BLPAR) and β-lactamase-producing clavulanic acid/amoxicillin-resistant H. influenzae (BLPACR) was 30.4%, 21.4%, 30.4%, 7.1%, and 10.7%, respectively. The isolation frequency of β-lactamase-nonproducing resistant H. influenzae (BLNAI+BLNAR) and β-lactamase-producing H. influenzae (BLPAR+BLPACR) was 51.8% and 17.8%, respectively. The following drugs displayed MIC₉₀ of ≤ 1 μg/mL against BLNAI, BLNAR, BLPAR and BLPACR: ceftriaxone, cefditoren, ciprofloxacin and levofloxacin, respectively.
This investigation found that existing use of previous antimicrobial agents was 44.6%. The significant decrease in isolation frequency of BLNAS and significant increase in isolation frequency of β-lactamase-producing H. influenzae were found to be dependent on existing use of previous antimicrobial agents.
A drug susceptibility survey of H. influenzae would lead to the establishment of using antibacterial agents properly for the prevention of increasingly resistant H. influenzae.

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1) Pharmacy, Showa University Koto Toyosu Hospital
2) Department of Hospital Pharmaceutics, School of Pharmacy, Showa University
3) Pediatric Surgery, Children's Medical Center, Showa University Koto Toyosu Hospital
4) Division of Pediatric Surgery, Department of Surgery, School of Medicine, Showa University
5) Pediatrics, Children's Medical Center, Showa University Koto Toyosu Hospital
6) Department of Pediatrics, School of Medicine, Showa University

Key words
Received	July 4, 2016
Accepted	April 13, 2017

29 (2)：119─126,2017