Coexistence of Plasmid-mediated Quinolone Resistance (PMQR) and Extended Spectrum β-lactamases (ESBLs) genes among clinical Pseudomonas aeruginosa isolates in Egypt

Abstract

Background: The rapid increasing prevalence of resistant P. aeruginosato widely used broad spectrum antibiotics as fluroquinolones and cephalosporins has become a matter of serious concern. Plasmid-mediated quinolone resistance (PMQR) have been recently identified as an emerging clinical problem among extended spectrum β-lactamases (ESBLs) producing gram negative bacteria. Methods: A total of 56 P. aeruginosa strains isolated from 330 patients with different infections were investigated for fluoroquinolone resistance phenotypically. Molecular methods were used to screen for 6 PMQR determinants among the fluoroquinolone-resistant isolates and for 3 ESBL genes among cephalosporin resistant isolates. Results: Overall, 22/56 (39.3%) of studied P. aeruginosa isolates were resistant to one or both tested fluoroquinolones. PMQR-producing P. aeruginosa isolates were identified in 20 isolates (90.9%). The acc(6ʹ)-1b-crwas the most prevalent PMQR gene (77.3%). The qnr genes were occurred in 72.7% of isolates. The qnrA gene was the most predominant 54.5%, followed by qnrS gene 27.3%, then each of qnrB and qnrC22.7%. The qepA was not detected in any isolate. The remarkable result of the current study was the high co-carriage of PMQR genes among the quinolone resistant isolates. Association of acc(6ʹ)-1b-cr with qnr genes was detected in 65% of positive PMQR isolates. Gene profiles carrying more than 2 PMQR genes were prevalent in P. aeruginosa isolates from wound and ear discharge. The ESBL genes were detected in 52% of cephalosporin resistant P. aeruginosa isolates. The most frequent ESBL gene was blaCTX-M(76.9%) followed by blaTEM (46.2%). Co-carriage of blaTEM and blaCTX-Mwas found in 23%. No isolates carried blaSHV. The ESBL genes positive isolates showed a significant higher resistance to non-beta lactam antibiotics. Regarding co-existence of PMQR and ESBL genes, at least 1 ESBL gene was found in 75% of PMQR-positive isolates. The acc(6ʹ)-Ib-cr gene showed the highest association with ESBL genes followed by qnrA gene. The correlation matrix of detected PMQR and ESBL genes indicated overall positive correlations. The strongest and highly significant correlation was between qnrAand acc(6ʹ)-Ib-cr (r = 0.602) and between qnrA and blaCTX-M (r = 0.519). Conclusion: The worldwide increased prevalence of ESBL producing and fluoroquinolone resistant P. aeruginosa strains became a serious threat to public health and a great challenge to treatment options. Studied P. aeruginosa isolates exhibited coexistence of PMQR and ESBL genes.