Infection and Drug Resistance (Dec 2021)
First Report of blaOXA-677 with Enhanced Meropenem-Hydrolyzing Ability in Pseudomonas aeruginosa in China
Abstract
Yue Sun,1,2 Renru Han,1,2 Li Ding,1,2 Yang Yang,1,2 Yan Guo,1,2 Shi Wu,1,2 Fupin Hu,1,2 Dandan Yin1,2 1Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China; 2Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People’s Republic of ChinaCorrespondence: Fupin Hu; Dandan Yin Tel/Fax +86 21 52888186; +86 21 52888196Email [email protected]; [email protected]: OXA-10-type class D β-lactamases have shown their evolutionary potential of enhancing carbapenem resistance. This study aimed to elucidate the role of OXA-10 variants in clinical isolated multidrug resistant (MDR) Pseudomonas aeruginosa and characterize the first appearance of OXA-677 in China.Methods: Six blaOXA-10-like-positive strains were screened by PCR from 41 P. aeruginosa strains, which were resistant to both carbapenems and ceftazidime-avibactam, collected across China in 2018. The minimum inhibitory concentrations (MIC) were determined with the broth microdilution method. The resistance-associated genes and genetic environment were investigated by whole-genome sequencing (WGS). The function and mechanism of OXA-677 β-lactamase were identified by molecular cloning and protein structure modeling.Results: All the blaOXA-10-like-positive Pseudomonas aeruginosa were MDR strains. They also had outer membrane porin defects and produced β-lactam resistance gene blaPER-1, fluoroquinolone-resistant gene crpP, aminoglycoside-resistance gene aph(3ʹ)-IIb, aph(6)-Id, aacA and aadA, fosfomycin-resistance gene fosA, sulfamethoxazole-resistance gene sul1, and chloramphenicol-resistance gene catB7. All blaOXA-10 variants were located in a Tn1403-related transposon, containing aacA4-12-blaOXA-677-aadA1, aacA4-12-blaOXA-101-aadA5, and blaOXA-246-aacA3-aadA13 gene cassette arrays, respectively. Notably, the blaOXA-677 producer showed a high MIC level of meropenem (MIC> 64 mg/L). Compared to blaOXA-10, blaOXA-677 was found a G-to-T transversion at position 350, leading to a phenylalanine-for-valine substitution in position 117, which is closer to leucine155 in the omega loop of the active site. MIC of meropenem for E. coli DH5α with the recombinant plasmid pHSG398 carrying blaOXA-677 was elevated by 8 times.Conclusion: We speculate that the OXA-10-like enzymes and the decrease of membrane permeability confer carbapenem resistance, and the V117 substitution in OXA-677 might lead to a higher resistance level of meropenem.Keywords: Pseudomonas aeruginosa, blaOXA-677, blaOXA-10-like gene, CHDL
