投稿分類 抗生素管制

主委發表種類: 壁報

投稿標題(中): 南台灣某區域醫院之抗碳青黴烯綠膿桿菌臨床分離株的體外ceftazidime-avibactam感受性

投稿標題(英): In vitro activity of ceftazidime-avibactam against carbapenem-resistant Pseudomonas aeruginosa clinical isolates at a regional hospital in southern Taiwan

投稿摘要: Introduction
Carbapenem-resistant Pseudomonas aeruginosa (CRPA) has emerged as one of frequently isolated bacteria that caused healthcare-associated infections. Given that CRPA exhibits low susceptibility to commonly prescribed antimicrobial agents, infections due to CRPA have been therefore very difficult to manage. High mortality rate of CRPA infections are doomed when traditional antibiotics are used. Newer antibiotics e.g., ceftazidime-avibactam (CAZ/AV), have been developed to increase antibiotic armamentarium for managing patients with multi-drug resistant bacterial infections; however, there are limited local data of CAZ/AV activity against CRPA clinical isolates. To better understand the in vitro activity of CAZ/AV against CRPA clinical isolates collected from Yuan’s General Hospital (YGH), minimal inhibitory concentrations (MICs) of CAZ/AV against CRPA clinical isolates were determined by ETEST method (bioMérieux, Marcy-I’Étoile, France).

Materials and Methods
Non-duplicate CRPA clinical isolates were collected from YGH in-patient setting between January and October, 2021. Bacterial isolates were speciated by VITEK 2 automated system according to manufacturer’s protocol. Further ETEST were performed if P. aeruginosa clinical isolates were resistant to meropenem by VITEK 2 antimicrobial susceptibility testing results.

Result
A total of 399 P. aeruginosa clinical isolates were collected during this period of time, 25 were non-duplicate CRPA. Twenty CRPA clinical isolates grew from specimens of respiratory tract secretions, 5 from urine samples, respectively. The sensitivity rate of CRPA clinical isolates to amikacin were 92%, ceftazidime 44%, cefepime 44%, gentamicin 72%, levofloxacin 24%, meropenem 0%, and piperacillin/tazobactam 24%, respectively. By performing ETEST of CRPA clinical isolates, MIC at which inhibited at least 90% bacterial growth (MIC90) were 8 μg/mL, MIC50 3 μg/mL, and geometric means of MICs 3.36 μg/mL, respectively. According to the performance standards for antimicrobial susceptibility testing by Clinical and Laboratory Standards Institute (CLSI), 92% CRPA clinical isolates were susceptible to CAZ/AV, and 8% resistant, respectively.

Conclusion
CAZ/AV exerted good activity against CRPA clinical isolates collected at YGH, MIC90 were 8 μg/mL of which fell in the category of susceptibility according to the performance standards for antimicrobial susceptibility testing by CLSI. In contrast to CAZ/AV, our study showed that less than 50% of CRPA clinical isolates were susceptible to β-lactam antimicrobial agents; the sensitivity rate of CRPA clinical isolates to β-lactam antimicrobial agents were so low that empirical therapy with these agents for CRPA infections inevitably failed. CAZ/AV offers a reasonable antibiotic option for the treatment of CRPA infections, further clinical studies targeted at CRPA infections warrants to justify our findings of this study.

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