Plasmid-Mediated Mechanism of Quinolone Resistance on Isolates from Different Clinical Samples.

Quinolone antimicrobials are widely used in clinical medicine due to their wide spectrum with high tissue penetration and ease of use; but increasing resistance with clinical use appears to be common in some bacterial pathogens, including Escherichia coli (). The aim of this study was to investigate plasmid-mediated quinolone resistance determinants (PMQR) including, A, B, and S as the emerging mechanisms of quinolone resistance of isolates from different clinical sites in Karbala province, Iraq. A total of 200 clinical samples were collected from patients suffering from infections such as UTI, gastro enteritis (diarrhea), vaginitis, and wound infections; 30 samples were diagnosed as clinical strain from both sexes and different ages after identification by biochemical test, VITEK-2 compact system, and by molecular method using 16Sr DNA marker. Antimicrobial susceptibility and minimal inhibition concentration (MIC) testing for nalidixic acid, norfloxacin, ciprofloxacin, levofloxacin, and gatifloxacin was performed using the broth microdilution method. All strains were screened for PMQR genes A, B, and S by the PCR method after DNA extraction from tested clinical isolates of . The results showed that is largely isolated from vaginal (40%) and urine (32%) samples, followed by wound infections (24%) and stools (21%).The high occurrence rate of (33.33%) isolates was observed in participants aged 31-45 years, while a lower occurrence (10%)was recorded in a group of ˃ 60-year-old female participants. Females have a notably increased frequency of compared to males, with the female to male ratio being 87%: 13%. Molecular investigation showed the total percentage of isolates harboring genes to be 21/30 (70%); this figure is composed of 14/30 isolates harboring in combined or mixed form (46.66%) and 7/30 (23.33%) isolates harboring in single form (3 isolates harboring A alone, 1 isolate harboring B alone, 3 isolates harboring S alone).The prevalence rates of A, B, and S were 40%, 43.33%, and 53.33%, respectively. The results also showed that among isolates encoding genes A, B, and S, 24%, 12%, and 36% were resistant to nalidixic acid, respectively. Among those isolates carrying A, B, and S genes, 15.8%, 5.3%, and 26.3%, respectively, were resistant to ciprofloxacin. Moreover, Norfloxacin resistance was seen in 20.0%, 5.0%, and 30.0% of isolates harboring A, B, and S genes, respectively. Levofloxacin resistance was seen in 37.5%, 75.0%, and 37.5% of the isolates carrying the A, B, and S genes, respectively. The lowest resistance rates of A, B, and S-positive strains were against gatifloxacin (0,0, and 25%, respectively).A high prevalence of genes enhances the increasing resistance rate of against the quinolone antibiotic under study.