Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh 160012, India; Department of Biotechnology, Maharishi Markandeshwar (Deemed to be) University, Mullana, Ambala, Haryana 133207, India.
Bacterial Genomics and Evolution Laboratory, CSIR-Institute of Microbial Technology, Sector - 39A, Chandigarh 160036, India.
Infect Genet Evol. 2019 Nov;75:103986. doi: 10.1016/j.meegid.2019.103986. Epub 2019 Jul 27.
Acinetobacter baumannii is a nosocomial pathogen increasingly affecting the critically ill patients and represents a major public health challenge. Carbapenem-resistant A. baumannii (CRAB) is found to be associated with International Clones (ICs) and different classes of carbapenemases. The objective of the present study was to investigate the prevalence of carbapenem resistance genes, clonal relationship and genetic structure of clinical isolates of A. baumannii. In the present study, multi-locus sequence typing (MLST) and analysis were carried out using Oxford scheme for 86 clinical isolates of CRAB along with 11 carbapenem sensitive A. baumannii (CSAB) collected over a period of two years (2014-2016) from two tertiary care hospitals of North India. We observed a high prevalence of the bla-like (97.7%) among the CRAB followed by bla (29.1%) and bla-like (3.5%). Forty-seven Sequence Types (STs) were represented by all 97 isolates, out of which, 28 (59.6%) were novel STs that were assigned to 41 isolates. STs 451 (13%), 447 (7%), 195 (6%) and 848 (5%) were the most common STs. The majority of CRAB isolates (44.3%) belonged to the CC92, followed by the CC447 (15.1%), CC109 (9.3%) and CC110 (3.4%), which corresponds to the IC2, 8, 1 and 7 respectively. Phylogenetic and recombination analysis suggested two major and one minor lineage in the population. Further linkage disequilibrium analysis suggested clonal nature of the population as recombination was noticed at a low frequency, which was not enough to split the clonal relationship. The knowledge of genetic structure of CRAB from this study will be invaluable to illustrate epidemiology, surveillance and understanding its global diversity.
鲍曼不动杆菌是一种医院获得性病原体，越来越多地影响重症患者，是一个主要的公共卫生挑战。耐碳青霉烯鲍曼不动杆菌（CRAB）被发现与国际克隆（IC）和不同类别的碳青霉烯酶有关。本研究的目的是调查临床分离的鲍曼不动杆菌碳青霉烯耐药基因、克隆关系和遗传结构的流行情况。在本研究中，对来自印度北部两家三级护理医院的 86 株临床 CRAB 分离株和 11 株碳青霉烯敏感鲍曼不动杆菌（CSAB）进行了多基因座序列分型（MLST）和分析，使用牛津方案进行。我们观察到 CRAB 中 bla 样（97.7%）的高流行率，其次是 bla（29.1%）和 bla 样（3.5%）。97 株分离株代表了 47 种序列类型（STs），其中 28 种（59.6%）是新型 STs，被分配给 41 种分离株。STs 451（13%）、447（7%）、195（6%）和 848（5%）是最常见的 STs。大多数 CRAB 分离株（44.3%）属于 CC92，其次是 CC447（15.1%）、CC109（9.3%）和 CC110（3.4%），分别对应于 IC2、8、1 和 7。系统发育和重组分析表明，该人群中有两个主要和一个次要谱系。进一步的连锁不平衡分析表明，该人群具有克隆性质，因为重组频率较低，不足以分裂克隆关系。本研究中 CRAB 遗传结构的知识对于说明其流行病学、监测和全球多样性将是非常宝贵的。
