Emergence of Carbapenem-Resistant ST244, ST292, and ST2446 Pseudomonas aeruginosa Clones in Burn Patients in Yunnan Province
Yue Fang, Zulqarnain Baloch, Wei Zhang, Ying Hu, Rui Zheng, Yuzhu Song, Wenlin Tai, Xueshan Xia
Abstract
Introduction: The prevalence of carbapenem-resistant Pseudomonas aeruginosa is increasing persistently, particularly in burn ward isolates. Here, we investigate the prevalence of carbapenem-resistant Pseudomonas aeruginosa in a burn ward of a provincial-level hospital at Kunming, Yunnan province, China. Methods: A total of 118 P. aeruginosa strains were isolated from 57 hospitalized patients, and their MICs were measured. Carbapenem-resistant isolates were selected for multilocus sequence typing (MLST). Carbapenem-resistance mechanisms were identified by examining carbapenemase genes and OprD protein and Carba-NP testing. Representative isolates were further characterized by de novo sequencing for carbapenemase molecular background. Results: Among 118 P. aeruginosa isolates, 54 (54/118,45.8%) were carbapenem-resistant Pseudomonas aeruginosa , and 3 genotypes were found (ST292, ST244, and ST2446). Non-carbapenemase-producing ST292 was the most prevalent ST, followed by ST2446 and ST244. A novel 13-bp oprD deletion was found in the ST292 clone, which formed the truncated outer membrane protein and may cause carbapenem resistance. ST244 and ST2446 harbored blaIMP-45 and blaIMP-87 , respectively. blaIMP-45 is located in a megaplasmid, together with aac(6’)-Ib3, blaOXA-1, catB3, qnrVC6, armA, msr(E), mph(E), aph(3’)-Ia, tetC / tetR, aac(6’)-Ib3, floR, mexC-mexD-oprJ, fosA and lead to extensive drug resistance. ST2446 contains a carbapenem-resistant gene blaIMP-87 on the chromosome and is acquired by a novel gene cassette array ( blaIMP-87-ant(2”)-Ia-blaOXA-10-aac(6’)-Ib3 ) of class 1 integron. Discussion: For the first time, ST244, ST292 and ST2446 are reported emerging in burn patients, with distinctive carbapenem-resistance mechanisms, respectively. The obtained results highlight the need to surveillance carbapenem-resistant isolates in burn patients. Keywords: P. aeruginosa , carbapenem-resistance, oprD , blaIMP