Nogbou Noel-David, Nkawane Granny M, Ntshane Khanyisa, Wairuri Charles K, Phofa Dikwata T, Mokgokong Kagiso K, Ramashia Mbudzeni, Nchabeleng Maphoshane, Obi Lawrence C, Musyoki Andrew M
Department of Microbiological Pathology, School of Medicine, Sefako Makgatho Health Sciences University, Pretoria, South Africa.
Microbiology Unit, National Health Laboratory Services, Dr George Mukhari Academic Hospital, Pretoria, South Africa.
Int J Microbiol. 2021 Oct 7;2021:9923816. doi: 10.1155/2021/9923816. eCollection 2021.
(. ) has developed several resistance mechanisms. The bacteria have been reported as origin of multiple outbreaks. This study aims to investigate the use of efflux pumps and quinolone resistance-associated genotypic mutations as mechanisms of resistance in . isolates at a tertiary hospital. A total number of 103 . isolates were investigated after identification and antimicrobial susceptibility testing by VITEK2 followed by PCR amplification of . Conventional PCR amplification of the AdeABC efflux pump (, , and ) and quinolone ( and ) resistance genes were performed, followed by quantitative real-time PCR of AdeABC efflux pump genes. Phenotypic evaluation of efflux pump expression was performed by determining the difference between the MIC of tigecycline before and after exposure to an efflux pump inhibitor. The Sanger sequencing method was used to sequence the and amplicons. A phylogenetic tree was drawn using MEGA 4.0 to evaluate evolutionary relatedness of the strains. All the collected isolates were -positive. High resistance to almost all the tested antibiotics was observed. Efflux pump was found in 75% of isolates as a mechanism of resistance. The study detected gene mutation in 60% and gene mutation in 85%, while 37% of isolates had mutations on both genes. A minimal evolutionary distance between the isolates was reported. The use of the AdeABC efflux pump system as an active mechanism of resistance combined with point mutation mainly in was shown to contribute to broaden the resistance spectrum of . isolates.
（.）已产生多种耐药机制。据报道，该细菌是多次暴发的源头。本研究旨在调查外排泵的使用情况以及喹诺酮耐药相关基因型突变作为某三级医院中. 分离株耐药机制的情况。通过VITEK2进行鉴定和抗菌药敏试验后，共对103株. 分离株进行了研究，随后对. 进行PCR扩增。对AdeABC外排泵（, , 和 ）和喹诺酮（ 和 ）耐药基因进行常规PCR扩增，随后对AdeABC外排泵基因进行定量实时PCR。通过测定替加环素在暴露于外排泵抑制剂前后的MIC差异来对外排泵表达进行表型评估。使用Sanger测序法对 和 扩增子进行测序。使用MEGA 4.0绘制系统发育树以评估菌株的进化相关性。所有收集的分离株均为. 阳性。观察到对几乎所有测试抗生素的高耐药性。发现75%的分离株存在外排泵作为耐药机制。该研究检测到60%的分离株存在 基因突变，85%的分离株存在 基因突变，而37%的分离株在两个基因上均有突变。报道了分离株之间的最小进化距离。结果表明，AdeABC外排泵系统作为一种活跃的耐药机制，与主要在 中的点突变相结合，有助于拓宽. 分离株的耐药谱。
