Department of Microbiology, Hamadan University of Medical Sciences, Hamadan, Iran.
Department of Microbiology, Tehran University of Medical Sciences, Tehran, Iran.
Sci Rep. 2024 Oct 29;14(1):25897. doi: 10.1038/s41598-024-77238-4.
Carbapenem-Resistant Acinetobacter baumannii (CRAB) outbreak in intensive care units (ICUs) is a significant problem for healthcare facilities. In this study, we aimed to investigate the occurrence of CRAB isolates among ICU-admitted patients during the three waves of the COVID-19 pandemic in Iran using Multiple-Locus Variable Number Tandem-Repeat Analysis (MLVA). We obtained 50 (A) baumannii isolates from tracheal aspirate and blood culture samples. In the disc diffusion method, all isolates were cefotaxime, ceftriaxone, and cefepime-resistant, while 98% (49/50) of isolates were resistant to piperacillin, piperacillin-tazobactam, ceftazidime, and ciprofloxacin. Levofloxacin and tobramycin resistance was found in 76% (38/50) of isolates. In the microbroth dilution test all isolates were resistant to imipenem, 98% (49/50) to meropenem, 68% (34/50) to colistin, and 20% (10/50) to polymyxin (B) Based on the PCR findings, all isolates harbored bla, ISAba-1, and int-2 genes. There were no isolates found that have the bla, bla, bla, bla, and int-3 genes. Among Extended-spectrum beta-lactamases (ESBL) genes, bla, bla, bla, bla, and bla have a prevalence of 42% (21/50), 84% (42/50), 58% (29/50), 78% (39/50), and 54% (27/50), respectively. 74% (37/50) of the isolates had the bla gene, while all of the isolates carried the bla gene. Among MBL genes, bla, bla, bla, and bla have a prevalence of 20% (10/50), 8% (4/50), 22% (11/50), and 60% (30/50), respectively. The prevalence of int-1 was documented as 74% (37/50). Accordingly, all isolates were identified as CRAB. The co-existence of bla/int-2 and bla/isaba-1 was 74% (37/50). The co-existence of bla/ISAba-1 was observed in 30 (60%) isolates. Using an 80% similarity threshold on the dendrogram constructed through MLVA typing, all isolates were grouped into two clusters: cluster A with 9 isolates from wave 3, and cluster B with 41 isolates from waves 3, 4, and 5. Our study confirms a clonal transmission of CRAB during the study period and suggests using molecular typing methods like MLVA in healthcare settings to identify dominant clones, antibiotic resistance patterns, and transmission routes. This will help to better manage the emergence and spread of antibiotic-resistant strains in future outbreaks.
耐碳青霉烯鲍曼不动杆菌（CRAB）在重症监护病房（ICU）的爆发是医疗机构面临的一个重大问题。在这项研究中，我们旨在使用多位点可变数目串联重复分析（MLVA）调查伊朗 COVID-19 大流行的三个波次中 ICU 入院患者中 CRAB 分离株的发生情况。我们从气管抽吸物和血液培养样本中获得了 50 株（A）鲍曼不动杆菌分离株。在纸片扩散法中，所有分离株均对头孢噻肟、头孢曲松和头孢吡肟耐药，而 98%（49/50）的分离株对哌拉西林、哌拉西林他唑巴坦、头孢他啶和环丙沙星耐药。76%（38/50）的分离株对左氧氟沙星和妥布霉素耐药。在微量肉汤稀释试验中，所有分离株均对亚胺培南、98%（49/50）对美罗培南、68%（34/50）对多粘菌素 B 和 20%（10/50）对多粘菌素（B）耐药。根据 PCR 结果，所有分离株均携带 bla、ISAba-1 和 int-2 基因。没有发现携带 bla、bla、bla、bla 和 int-3 基因的分离株。在扩展型β-内酰胺酶（ESBL）基因中，bla、bla、bla、bla 和 bla 的流行率分别为 42%（21/50）、84%（42/50）、58%（29/50）、78%（39/50）和 54%（27/50）。74%（37/50）的分离株携带 bla 基因，而所有分离株均携带 bla 基因。在金属β-内酰胺酶（MBL）基因中，bla、bla、bla 和 bla 的流行率分别为 20%（10/50）、8%（4/50）、22%（11/50）和 60%（30/50）。int-1 的流行率为 74%（37/50）。因此，所有分离株均被鉴定为 CRAB。bla/int-2 和 bla/ISAba-1 的共存率为 74%（37/50）。bla/ISAba-1 的共存率在 30 株（60%）分离株中观察到。在使用 MLVA 分型构建的聚类树上使用 80%的相似性阈值，所有分离株分为两个簇：第 3 波的簇 A，有 9 株，第 3、4 和 5 波的簇 B，有 41 株。我们的研究证实了 CRAB 在研究期间的克隆传播，并建议在医疗机构中使用分子分型方法，如 MLVA，以识别优势克隆、抗生素耐药模式和传播途径。这将有助于更好地管理未来爆发中抗生素耐药菌株的出现和传播。
