Description and plasmid characterization of the qnrD determinant in Proteeae in Wenzhou, Southern China

Lijiang Chen, Yapei Zhang, Jia Du, Xiaolei Zhang, Meimei Li, Huale Chen, Xiao Yu, Yao Sun, Tieli Zhou
2018 Journal of Microbiology, Immunology and Infection  
Background/Purpose: Only limited information is available about the detailed characteristics of qnrD, a plasmid-mediated quinolone resistance (PMQR) gene. This study aimed to understand the distribution of qnrD and the characterization of qnrD-carrying plasmids in Proteeae. Methods: The distribution of qnrD genes was investigated by polymerase chain reaction (PCR) amplification in 203 consecutive nonduplicate clinical isolates of Proteeae collected from inpatients at the First Affiliated The
more » ... t Affiliated The minimum inhibitory concentrations (MICs) of antibiotics were measured by agar dilution method and other PMQR determinants were also determined by PCR. qnrD was positioned via Southern hybridization and the transferability of qnrD-carrying plasmids was achieved by conjugation experiment. The genetic environment of qnrD was investigated by sequencing, and chromosomal polymorphism for qnrD-positive strains was analyzed by pulsed-field gel electrophoresis (PFGE). Results: Forty strains carried qnrD, showing decreased fluoroquinolone susceptibility or lowlevel fluoroquinolone resistance. qnrD was encoded on the plasmid of about 2.7 kb or 5.2 kb in length, which cannot be transferred by liquid conjugation or filter mating, but can be successfully transferred by transduction. The transformants showed 62.5e300-fold increases in the MICs of quinolones compared with the recipient. The plasmids carrying qnrD showed a high similarity with that of Providencia spp. and Proteus vulgaris. PFGE analysis demonstrated that these isolates were divergent and not clone related. Journal of Microbiology, Immunology and Infection (2016) xx, 1e8 Conclusion: qnrD could have originated from Proteeae or presented in these bacteria as a reservoir; furthermore, qnrD could be transferred and spread within the same or across different bacterial species if the plasmids acquired mobile elements under antimicrobial selective pressures.
doi:10.1016/j.jmii.2016.02.001 pmid:27049282 fatcat:ep3ctwic3nh37kd4tmuhfa4vwq