부산대학교 도서관

ABSTRACT: Objectives: This study aimed to characterize Gram negative bacteria carrying blaGES carbapenemase genes detected in wastewater from a hospital with no history of detection of clinical isolates producing GES carbapenemases. Methods: Six hospital effluent samples were screened for carbapenemase-producing organisms (CPO) using CHROMagar mSuperCARBA and MacConkey agar with 1 µg/mL imipenem. Polymerase chain reaction (PCR) amplification and sequencing of carbapenemase genes, multilocus sequence typing, antimicrobial susceptibility testing, and whole-genome sequencing were performed. Results: Among 21 CPO isolates, 11 Klebsiella spp. and 5 Enterobacter kobei isolates carried blaGES-24, and 4 E. roggenkampii and 1 Pseudomonas aeruginosa isolates carried blaGES-5. Genomic analysis of 8 representative isolates comprising 6 blaGES-24-positive and 2 blaGES-5-positive revealed that class 3 integrons with complete or defective Tn402-like transposition modules were predominantly associated with two tandem copies of blaGES-24. Furthermore, a total of 5 new class 3 integrons, In3-18 to In3-22, were identified among 5 blaGES-24 and 1 blaGES-5 plasmids. One strain each of K. pneumoniae subsp. pneumoniae and K. quasipneumoniae subsp. similipneumoniae harboring blaGES-24 plasmids also carried a rare blaVEB-1-positive class 1 integron on a non-typeable plasmid, where these blaVEB-1 plasmids had high sequence similarity. Virulence gene profiles differed between Klebsiella spp. and Enterobacter spp.; the former harbored type III fimbriae cluster, salmochelin, and T6SS type i2 gene clusters, while the latter had curli pili operon, aerobactin, T2SS gene clusters, and T6SS type i3 gene clusters. Conclusion: Our findings confirmed the linkage of blaGES-24 with rare Tn402-like class 3 integrons and the structural diversity of their gene cassette arrays.