Tabriz Research Center of Infectious and Tropical Diseases, Tabriz University of Medical Sciences, Tabriz, Iran; Microbiology Department, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
Burns. 2013 Nov;39(7):1414-9. doi: 10.1016/j.burns.2013.03.024. Epub 2013 May 29.
We examined the prevalence of various carbapenem resistance mechanisms in clinical isolates of Acinetobacter baumannii collected from hospitalized burn and non-burn patients. Antimicrobial susceptibility testing was performed for 43 burn and 32 non-burn isolates. Carbapenem resistance genes were identified and repetitive extragenic palindromic PCR (REP-PCR) was used to define clonal relatedness. CarO disruption was investigated by PCR and its expression analyzed by real time reverse transcription-PCR. Of the sixty-four (85%) carbapenem resistant A. baumannii isolates, 42 (66%) and 22 (34%) strains were recovered from burn and non-burn patients, respectively. Isolates were categorized into 6 major REP-PCR patterns; with the highest prevalence of non-burn and burn isolates in pattern A (63%) and B (35%), respectively. Prevalence of blaOXA-23 was 68% and isolates harbored this element belonged to all REP clusters. The blaOXA-40-like was detected in 49% of isolates, with higher prevalence among burn isolates. Three of the four isolates lacked carO gene were cultured from burn patients and level of the carO expression was decreased in carbapenem resistant isolates. These findings show that blaOXA-23 is widely distributed in carbapenem resistant A. baumannii isolates and other resistance mechanisms such as blaOXA-40-like and loss or decreased carO expression could be added in burn strains.
我们研究了从住院烧伤和非烧伤患者中分离的鲍曼不动杆菌临床分离株中各种碳青霉烯类耐药机制的流行情况。对 43 株烧伤和 32 株非烧伤分离株进行了抗菌药物敏感性试验。鉴定了碳青霉烯类耐药基因，并采用重复扩展基因回文 PCR（REP-PCR）来定义克隆相关性。通过 PCR 研究了 CarO 缺失，并通过实时逆转录-PCR 分析了其表达。在 64 株（85%）碳青霉烯类耐药的鲍曼不动杆菌分离株中，分别有 42 株（66%）和 22 株（34%）从烧伤和非烧伤患者中分离出来。分离株分为 6 种主要的 REP-PCR 模式；非烧伤和烧伤分离株中 A 型（63%）和 B 型（35%）的流行率最高。blaOXA-23 的检出率为 68%，携带该基因的分离株属于所有 REP 群。blaOXA-40 样基因在 49%的分离株中检测到，烧伤分离株中该基因的检出率更高。从烧伤患者中培养出的 4 株缺失 carO 基因的分离株中，有 3 株缺失 carO 基因，且耐碳青霉烯类的分离株 carO 基因表达水平降低。这些发现表明，blaOXA-23 在碳青霉烯类耐药的鲍曼不动杆菌分离株中广泛分布，其他耐药机制，如 blaOXA-40 样和 carO 基因的缺失或表达降低，可能在烧伤株中存在。
