Venkataramana Geetha P, Lalitha Aishwarya K V, Mariappan Shanthi, Sekar Uma
Department of Microbiology, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, Tamil Nadu, India.
J Lab Physicians. 2022 Feb 9;14(3):271-277. doi: 10.1055/s-0042-1742636. eCollection 2022 Sep.
and are important pathogens in health care-associated infections. Fluoroquinolone resistance has emerged in these pathogens. In this study, we aimed to determine the occurrence of plasmid-mediated quinolone resistance (PMQR) determinants ( , , , , , and ) by polymerase chain reaction (PCR) and the transmissibility of plasmid-borne resistance determinants in clinical isolates of and . The study included (85) and (45) which were nonduplicate, clinically significant, and ciprofloxacin resistant. Antibiotic susceptibility testing was done by disk diffusion method for other antimicrobial agents, namely amikacin, ceftazidime, piperacillin/tazobactam, ofloxacin, levofloxacin, and imipenem. Minimum inhibitory concentration of ciprofloxacin was determined. Efflux pump activity was evaluated using carbonyl-cyanide m-chlorophenylhydrazone (CCCP). The presence of PMQR genes was screened by PCR amplification. Transferability of PMQR genes was determined by conjugation experiment, and plasmid-based replicon typing was performed. Resistance to other classes of antimicrobial agents was as follows: ceftazidime (86.9%), piperacillin/tazobactam (73.8%), imipenem (69.2%), and amikacin (63.8%). The minimal inhibitory concentration (MIC)50 and MIC90 for ciprofloxacin were 64 and greater than or equal to 256 µg/mL, respectively. There was a reduction in MIC for 37 (28.4%) isolates with CCCP. In , 12 (14.1%) isolates harbored , 12 (14.1%) , 9 (10.5%) both and , 66 (77.6%) , and 3 (3.5%) gene. In , was detected in 2 (4.4%), 1 (2.2%) harbored both the and , 1 isolate harbored and , 21 (46.6%) , and 1 (2.2%) isolate harbored gene. Notably, gene was not detected in any of the study isolates. Conjugation experiments revealed that 12 (9.2%) were transferable. Of the transconjugants, seven (58.3%) belonged to IncFII type plasmid replicon, followed by four (33.3%) IncA/C and one (8.3%) IncFIC type. The plasmid-mediated resistance gene is primarily responsible for mediating fluoroquinolone resistance in clinical isolates of . and . The predominant plasmid type is IncFII.
[具体细菌名称1]和[具体细菌名称2]是医疗保健相关感染中的重要病原体。这些病原体中已出现氟喹诺酮耐药性。在本研究中，我们旨在通过聚合酶链反应（PCR）确定质粒介导的喹诺酮耐药性（PMQR）决定簇（[具体决定簇1]、[具体决定簇2]、[具体决定簇3]、[具体决定簇4]、[具体决定簇5]和[具体决定簇6]）的出现情况，以及[具体细菌名称1]和[具体细菌名称2]临床分离株中质粒携带的耐药决定簇的可传播性。
该研究纳入了[具体细菌名称1]（85株）和[具体细菌名称2]（45株），这些菌株均为非重复、具有临床意义且对环丙沙星耐药。采用纸片扩散法对其他抗菌药物进行药敏试验，这些抗菌药物包括阿米卡星、头孢他啶、哌拉西林/他唑巴坦、氧氟沙星、左氧氟沙星和亚胺培南。测定了环丙沙星的最低抑菌浓度。使用羰基氰化物间氯苯腙（CCCP）评估外排泵活性。通过PCR扩增筛选PMQR基因的存在情况。通过接合实验确定PMQR基因的可转移性，并进行基于质粒的复制子分型。
头孢他啶（86.9%）、哌拉西林/他唑巴坦（73.8%）、亚胺培南（69.2%）和阿米卡星（63.8%）。环丙沙星的最低抑菌浓度（MIC）50和MIC90分别为64和大于或等于256 μg/mL。37株（28.4%）分离株经CCCP处理后MIC降低。在[具体细菌名称1]中，12株（14.1%）分离株携带[具体基因1]，12株（14.1%）携带[具体基因2]，9株（10.5%）同时携带[具体基因1]和[具体基因2]，66株（77.6%）携带[具体基因3]，3株（3.5%）携带[具体基因4]。在[具体细菌名称2]中，2株（4.4%）检测到[具体基因1]，1株（2.2%）同时携带[具体基因1]和[具体基因2]，1株分离株携带[具体基因1]和[具体基因3]，21株（46.6%）携带[具体基因3]，1株（2.2%）分离株携带[具体基因4]。值得注意的是，在任何研究分离株中均未检测到[具体基因5]。接合实验显示12株（9.2%）可转移。在转接合子中，7株（58.3%）属于IncFII型质粒复制子，其次是4株（33.3%）IncA/C型和1株（8.3%）IncFIC型。
质粒介导的耐药[具体基因1]主要负责介导[具体细菌名称1]和[具体细菌名称2]临床分离株中的氟喹诺酮耐药性。主要的质粒类型是IncFII。
