# Antimicrobial activities of piperacillin-tazobactam against Haemophilus influenzae isolates, including β-lactamase-negative ampicillin-resistant and β-lactamase-positive amoxicillin-clavulanate-resistant isolates, and mutations in their quinolone resistance-determining regions
> Hirakata Y.

URL kanonis: https://discover.unhas.ac.id/publications/pub_scopus_70349342840
Jurnal / Konferensi: Antimicrobial Agents and Chemotherapy
Tahun terbit: 2009
DOI: https://doi.org/10.1128/AAC.00192-09
ISSN: 00664804
Kuartil SJR: Q1
Citations: 24

## Authors
- Hirakata Y.

## Abstract
Beta-lactamase-negative ampicillin-resistant (BLNAR) isolates of Haemophilus influenzae have been emerging in some countries, including Japan. The Clinical and Laboratory Standards Institute has only a susceptible MIC breakpoint (< or = 1 microg/ml) for piperacillin-tazobactam and a disclaimer comment that BLNAR H. influenzae should be considered resistant, which was adapted without presentation of data. In addition, fluoroquinolone-resistant H. influenzae isolates have recently been occasionally reported worldwide. To address these problems, we examined susceptibilities to beta-lactams, including piperacillin-tazobactam, and ciprofloxacin by microdilution and disk diffusion (only for piperacillin-tazobactam) methods, against a total of 400 recent H. influenzae clinical isolates, including 100 beta-lactamase-negative ampicillin-susceptible, beta-lactamase-positive ampicillin-resistant, BLNAR, and beta-lactamase-positive amoxicillin-clavulanate-resistant (BLPACR) isolates each. BLNAR and BLPACR isolates were tested by PCR using primers that amplify specific regions of the ftsI gene. We also detected mutations in quinolone resistance-determining regions (QRDRs) by direct sequencing of the PCR products of DNA fragments. Among beta-lactams, piperacillin-tazobactam exhibited potent activity against all isolates of H. influenzae, with all MICs at < or = 0.5 microg/ml (susceptible). A disk diffusion breakpoint for piperacillin-tazobactam of > or = 21 mm is proposed. We confirmed that all BLNAR and BLPACR isolates had amino acid substitutions in the ftsI gene and that the major pattern was group III-like (87.5%). One ciprofloxacin-resistant isolate (MIC, 16 microg/ml) and 31 ciprofloxacin-susceptible isolates (MICs, 0.06 to 0.5 microg/ml) had amino acid changes in their QRDRs. Piperacillin-tazobactam was the most potent beta-lactam tested against all classes of H. influenzae isolates. It is possible that fluoroquinolone-resistant H. influenzae will emerge since several clinical isolates carried mutations in their QRDRs.

## Keywords
- Piperacillin
- Microbiology
- Tazobactam
- Biology
- Ampicillin
- Haemophilus influenzae
- Ciprofloxacin
- Piperacillin/tazobactam
- Amp resistance
- Virology
- Antibiotic resistance
- Imipenem
- Antibiotics
- Genetics
- Bacteria
- Pseudomonas aeruginosa

---
Sumber: Discover Unhas — RIMS Universitas Hasanuddin.
Saat mengutip, gunakan DOI bila tersedia atau URL kanonis di atas.