Prevalence of Plasmid-Mediated Quinolone Resistance Determinants over a 9-Year Period

Abstract

Recently, several plasmid-mediated quinolone resistance (PMQR) genes conferring low levels of quinolone resistance have been discovered. To evaluate the temporal change in the prevalence of PMQR genes over a decade in a tertiary hospital in the Republic of Korea, we selected every fifth isolate of Escherichia coli and Klebsiella pneumoniae and every third isolate of Enterobacter cloacae between 1998 and 2001 and between 2005 and 2006 from a collection of blood isolates. Six PMQR genes [qnrA, qnrB, qnrC, qnrS, aac(6)-Ib-cr, and qepA] were screened by multiplex PCR and then confirmed by direct sequencing, and the aac(6)-Ib-positive PCR products were digested with BtsCI to identify the aac(6)-Ib-cr variant. Of 461 isolates, 37 (8%) had one of the six PMQR genes; 13 (5%) of 261 E. coli strains, 13 (10%) of 135 K. pneumoniae strains, and 11 (17%) of 65 E. cloacae strains. qnrB was the most common PMQR gene and was found as early as 1998, whereas qnrS, aac(6)-Ib-cr, and qepA emerged after 2000. None of the isolates carried qnrA or qnrC. Ciprofloxacin resistance increased over time (P < 0.001), and the overall prevalence of PMQR genes tended to increase (P ‫؍‬ 0.20). PMQR-positive isolates had significantly higher ciprofloxacin resistance and multidrug resistance rates (P ‫؍‬ 0.005 and P < 0.001, respectively). The increasing frequency of ciprofloxacin resistance in Enterobacteriaceae was associated with an increasing prevalence of PMQR genes, and this change involved an increase in the diversity of the PMQR genes and also an increase in the prevalence of the mutations in gyrA, parC, or both in PMQR-positive strains but not PMQR-negative strains.

High prevalence of plasmid-mediated quinolone resistance determinants in Enterobacter cloacae isolated from hospitals of the Qazvin, Alborz, and Tehran provinces, Iran

“…from Tunisia (16%) (32) , Wu et al (10) . from Taiwan (16.3%) (10) , Kim et al (33) . from Korea (17%) (33) , and Robicsek et al (34) .…”

“…from Taiwan (16.3%) (10) , Kim et al (33) . from Korea (17%) (33) , and Robicsek et al (34) . from the United States (31%) (34) .…”

Detection of the Smqnr quinolone protection gene and its prevalence in clinical isolates of Stenotrophomonas maltophilia in China

“…For the resistant isolates, screening of the five PMQR determinants qnrA, qnrB, qnrC, qnrD and qnrS and identification of mutations in the gyrA and parE genes were carried out by PCR and sequence analysis. The primers used for the PMQR determinants and the PCR procedure have been described previously (Kim et al, 2009). …”

Antibiotic resistance, plasmid-mediated quinolone resistance (PMQR) genes and ampC gene in two typical municipal wastewater treatment plants

“…Quinolone resistance was considered to be acquired only by chromosomal mutations until plasmid-mediated quinolone resistance (PMQR) was rst reported in a Klebsiella pneumoniae clinical strain isolated in 1994 in Birmingham, Alabama, 17 and so far PMQR strains have been reported worldwide from unrelated species. [18][19][20] Quinolone resistance genes consist of qnrA, qnrB, qnrC, qnrD, qnrS, encoding DNA gyrase and/or topoisomerase IV; qepA, regulating the expression of efflux pumps and aac(6 0 )-Ib-cr, encoding a variant aminoglycoside acetyltransferase that modies ciprooxacin. 17,18,21 Besides PMQR genes, plasmidmediated ampC is under the spotlights because of its ability of hydrolyzation of third-generation cephalosporins.…”