Department of Biology, College of Science, University of Babylon, Hilla, Iraq.
General Directorate of Education in Kerbala, Kerbala, Iraq.
Eur J Med Res. 2024 Aug 14;29(1):419. doi: 10.1186/s40001-024-02007-y.
The purpose of this study was to look into the presence of plasmid-mediated quinolone resistance (PMQR) genes and biofilm formation in several species of clinical Shigella isolates that were resistant to quinolones.
The stool samples of 150 patients (younger than 10 years) with diarrhea were collected in this cross-sectional study (November 2020 to December 2021). After cultivation of samples on Hektoen Enteric agar and xylose lysine deoxycholate agar, standard microbiology tests, VITEK 2 system, and polymerase chain reaction (PCR) were utilized to identify Shigella isolates. The broth microdilution method was used to determine antibiotic susceptibility. PMQR genes including qnrA, qnrB, qnrC, qnrD, qnrE, qnrS, qnrVC, qepA, oqxAB, aac(6')-Ib-cr, and crpP and biofilm formation were investigated in quinolone-resistant isolates by PCR and microtiter plate method, respectively. An enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) technique was used to determine the clonal relatedness of quinolone-resistant isolates.
A total of 95 Shigella isolates including S. sonnei (53, 55.8%), S. flexneri (39, 41.1%), and S. boydii (3, 3.2%) were identified. The highest resistance rates of the isolates were against ampicillin (92.6%, n = 88/95). Overall, 42 of 95 (44.2%) isolates were simultaneously resistant against two or more quinolones including 26 (61.9%) S. sonnei and 16 (38.1%) S. flexneri. All isolates were multidrug-resistant (resistance to more than 3 antibiotics). The occurrence of PMQR genes was as follows: qnrS (52.4%), qnrA and aac(6')-Ib-cr (33.3%), and qnrB (19.0%). The prevalence in species was as follows: 61.5% and 37.5% (qnrS), 19.2% and 56.3% (qnrA), 38.5% and 25.0 (aac(6')-Ib-cr), and 19.2% and 18.8% (qnrB) for S. sonnei and S. flexneri, respectively. The other PMQR genes were not detected. In total, 52.8% (28/53) of quinolone-susceptible and 64.3% (27/42) of quinolone-resistant isolates were biofilm producers. Biofilm formation was not significantly different between quinolone-resistant and quinolone-susceptible isolates (P-value = 0.299). Quinolone-resistant isolates showed a high genetic diversity according to the ERIC-PCR.
It seems that qnrS, qnrA, and aac(6')-Ib-cr play a significant role in the quinolone resistance among Shigella isolates in our region. Also the quinolone-resistant S. flexneri and S. sonnei isolates had a high genetic diversity. Hence, antibiotic therapy needs to be routinely revised based on the surveillance findings.
本研究旨在调查对喹诺酮类药物耐药的几种临床志贺菌分离株中存在的质粒介导的喹诺酮耐药（PMQR）基因和生物膜形成情况。
在这项横断面研究中（2020 年 11 月至 2021 年 12 月），收集了 150 名（年龄均<10 岁）腹泻患者的粪便样本。在 Hektoen 肠琼脂和木糖赖氨酸去氧胆酸盐琼脂上培养样本后，利用标准微生物学检测、VITEK 2 系统和聚合酶链反应（PCR）鉴定志贺菌分离株。采用肉汤微量稀释法测定抗生素敏感性。通过 PCR 和微量滴定板法分别研究了喹诺酮耐药分离株中 PMQR 基因（包括 qnrA、qnrB、qnrC、qnrD、qnrE、qnrS、qnrVC、qepA、oqxAB、aac(6')-Ib-cr 和 crpP）和生物膜形成情况。采用肠杆菌重复基因间一致性聚合酶链反应（ERIC-PCR）技术确定喹诺酮耐药分离株的克隆相关性。
共鉴定出 95 株志贺菌分离株，包括 S. sonnei（53 株，占 55.8%）、S. flexneri（39 株，占 41.1%）和 S. boydii（3 株，占 3.2%）。分离株对氨苄西林的耐药率最高（92.6%，n=88/95）。总体而言，95 株分离株中有 42 株（44.2%）同时对两种或两种以上喹诺酮类药物耐药，其中 26 株（61.9%）为 S. sonnei，16 株（38.1%）为 S. flexneri。所有分离株均为多重耐药（对 3 种以上抗生素耐药）。PMQR 基因的检出情况如下：qnrS（52.4%）、qnrA 和 aac(6')-Ib-cr（33.3%）和 qnrB（19.0%）。在种属中的流行情况如下：qnrS（61.5%和 37.5%）、qnrA（19.2%和 56.3%）、aac(6')-Ib-cr（38.5%和 25.0%）和 qnrB（19.2%和 18.8%），分别为 S. sonnei 和 S. flexneri。未检出其他 PMQR 基因。在喹诺酮敏感分离株中，52.8%（28/53）为生物膜形成者，在喹诺酮耐药分离株中，64.3%（27/42）为生物膜形成者。喹诺酮耐药分离株和喹诺酮敏感分离株的生物膜形成率无显著差异（P 值=0.299）。根据 ERIC-PCR，喹诺酮耐药分离株显示出较高的遗传多样性。
qnrS、qnrA 和 aac(6')-Ib-cr 似乎在本地区志贺菌分离株对喹诺酮类药物的耐药中起重要作用。此外，耐喹诺酮的 S. flexneri 和 S. sonnei 分离株具有较高的遗传多样性。因此，需要根据监测结果定期修订抗生素治疗方案。
