比较黏菌素肉汤纸片洗脱法（CBDE）和肉汤微量稀释法（BMD）在铜绿假单胞菌临床分离株中的应用，特别关注异质性耐药。
Comparative evaluation of colistin broth disc elution (CBDE) and broth microdilution (BMD) in clinical isolates of Pseudomonas aeruginosa with special reference to heteroresistance.
机构信息
Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, India.
出版信息
Indian J Med Microbiol. 2024 Jan-Feb;47:100494. doi: 10.1016/j.ijmmb.2023.100494. Epub 2023 Oct 25.
PURPOSE
Antimicrobial resistance (AMR) in Pseudomonas aeruginosa has been ever-increasing. Among other reasons, colistin resistance might be attributed to limited routine testing by approved methods. Both broth microdilution (BMD) and colistin broth disc elution (CBDE) methods have been advocated, with limited data on the performance of these methods in the Indian settings. This prospective study was conducted to determine colistin resistance in P. aeruginosa, compare the BMD and CBDE methods with special reference to heteroresistance.
MATERIALS AND METHODS
A total of 100 isolates of P. aeruginosa from admitted patients were included. Antimicrobial susceptibility testing was done against standard antibiotics by disc diffusion test. Minimum inhibitory concentration (MIC) against polymyxins was studied by BMD and CBDE (for colistin only). Heteroresistance to colistin was studied by population analysis profile (PAP). CBDE and BMD were compared by performance calculations. Discrepancy in results were analyzed based on heteroresistance.
RESULTS
Majority of the P. aeruginosa isolates were from pus samples (62, 62 %). Disc diffusion method revealed maximum susceptibility towards aztreonam (74, 74 %) followed by meropenem (68, 68 %) and piperacillin-tazobactam (65, 65 %). Polymyxin B resistance was seen in 6 % (6) while colistin resistance was seen in 9 % (9) isolates by BMD. CBDE revealed 8 % (8) resistance to colistin, having 97 % essential agreement and 95 % categorical agreement with BMD. Further, by PAP analysis, 9 isolates were resistant to colistin which included 9 resistant isolates by BMD. On discrepancy analysis, 1 isolate was found to be heteroresistant to colistin. No heteroresistance was seen in the isolates that were susceptible by all the methods.
CONCLUSIONS
Heteroresistance to colistin in P. aeruginosa accounted for the discrepancy in results where CBDE method failed to detect heteroresistant isolate. As heteroresistance is a least studied phenotype, it's exact prevalence should be studied so that challenges in susceptibility testing could be addressed.
目的
铜绿假单胞菌的抗菌药物耐药性（AMR）一直在不断增加。造成这种情况的原因之一是，由于缺乏批准方法的常规检测，可能导致多粘菌素耐药。已提倡使用肉汤微量稀释（BMD）和多粘菌素肉汤纸片洗脱（CBDE）方法，但关于这些方法在印度环境中的性能的数据有限。本前瞻性研究旨在确定铜绿假单胞菌的多粘菌素耐药性，比较 BMD 和 CBDE 方法，特别是异质性耐药性。
材料和方法
共纳入 100 例住院患者的铜绿假单胞菌分离株。采用纸片扩散试验对标准抗生素进行抗菌药物敏感性试验。通过 BMD 和 CBDE（仅用于多粘菌素）研究多粘菌素最低抑菌浓度（MIC）。通过群体分析谱（PAP）研究多粘菌素的异质性耐药性。通过性能计算比较 CBDE 和 BMD。基于异质性耐药性分析结果差异。
结果
大多数铜绿假单胞菌分离株来自脓液样本（62，62%）。纸片扩散法显示对氨曲南（74，74%）的敏感性最高，其次是美罗培南（68，68%）和哌拉西林-他唑巴坦（65，65%）。多粘菌素 B 耐药性见于 6 例（6%），BMD 检测到 9 例（9%）分离株对多粘菌素耐药。CBDE 显示 8 例（8%）对多粘菌素耐药，与 BMD 的基本符合率为 97%，分类符合率为 95%。进一步通过 PAP 分析，9 例对多粘菌素耐药，其中包括 9 例 BMD 耐药的分离株。在差异分析中，发现 1 例对多粘菌素呈异质性耐药。所有方法均敏感的分离株未观察到异质性耐药。
结论
铜绿假单胞菌对多粘菌素的异质性耐药性导致 CBDE 方法未能检测到异质性耐药分离株，从而导致结果差异。由于异质性耐药是研究最少的表型，因此应研究其确切流行率，以解决药敏试验中的挑战。
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