دورية
Carbapenem-Nonsusceptible Haemophilus influenzaewith Penicillin-Binding Protein 3 Containing an Amino Acid Insertion
العنوان: | Carbapenem-Nonsusceptible Haemophilus influenzaewith Penicillin-Binding Protein 3 Containing an Amino Acid Insertion |
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المؤلفون: | Kitaoka, Kazuki, Kimura, Kouji, Kitanaka, Hiromitsu, Banno, Hirotsugu, Jin, Wanchun, Wachino, Jun-ichi, Arakawa, Yoshichika |
المصدر: | Antimicrobial Agents and Chemotherapy; May 2018, Vol. 62 Issue: 8 |
مستخلص: | ABSTRACTThe prevalence of β-lactamase-negative ampicillin-resistant (BLNAR) Haemophilus influenzaehas become a clinical concern. In BLNAR isolates, amino acid substitutions in penicillin-binding protein 3 (PBP3) are relevant to the β-lactam resistance. Carbapenem-nonsusceptible H. influenzaeisolates have been rarely reported. Through antimicrobial susceptibility testing, nucleotide sequence analysis of ftsI, encoding PBP3, and the utilization of a collection of H. influenzaeclinical isolates in our laboratory, we obtained a carbapenem-nonsusceptible clinical isolate (NUBL1772) that possesses an altered PBP3 containing V525_N526insM. The aim of this study was to reveal the effect of altered PBP3 containing V525_N526insM on reduced carbapenem susceptibility. After generating recombinant strains with altered ftsI, we performed antimicrobial susceptibility testing and competitive binding assays with fluorescent penicillin (Bocillin FL) and carbapenems. Elevated carbapenem MICs were found for the recombinant strain harboring the entire ftsIgene of NUBL1772. The recombinant PBP3 of NUBL1772 also exhibited reduced binding to carbapenems. These results demonstrate that altered PBP3 containing V525_N526insM influences the reduced carbapenem susceptibility. The revertant mutant lacking the V525_N526insM exhibited lower MICs for carbapenems than NUBL1772, suggesting that this insertion affects reduced carbapenem susceptibility. The MICs of β-lactams for NUBL1772 were higher than those for the recombinant possessing ftsIof NUBL1772. NUBL1772 harbored AcrR with early termination, resulting in low-level transcription of acrBand high efflux pump activity. These findings suggest that the disruption of AcrR also contributes to the reduced carbapenem susceptibility found in NUBL1772. Our results provide the first evidence that the altered PBP3 containing V525_N526insM is responsible for the reduced susceptibility to carbapenems in H. influenzae. |
قاعدة البيانات: | Supplemental Index |
تدمد: | 00664804 10986596 |
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DOI: | 10.1128/AAC.00671-18 |