Clinical and molecular characteristics of isolates at a teaching hospital in Shanghai, China.

BACKGROUND

(. ) has recently emerged as a cause of life-threatening nosocomial infections in humans. This study aims to investigate the clinical characteristics, homology, and antimicrobial patterns of . clinical isolates at a teaching hospital in Shanghai, China.

METHODS

A total of 135 consecutive non-replicate clinical isolates from January 2010 to December 2018 were collected at a tertiary care university hospital in Shanghai, China. Genetic relatedness of the isolates was performed by pulsed-field gel electrophoresis (PFGE). The antimicrobial susceptibility of these isolates was measured by the microdilution broth method. The prevalence of β-lactamase genes was investigated by polymerase chain reaction (PCR), while the quinolone resistance-determining regions (QRDRs) were sequenced.

RESULTS

All 135 isolates were collected from hospitalized patients with an average age of 55 years. Most of these clinical isolates were derived from ascites (59.3%) or urine (23.7%) specimens. Eighty (80/135) of the strains were classified as clone D by PFGE. drug susceptibility tests showed that minocycline and trimethoprim-sulfamethoxazole had sound antibacterial effects. However, more than 86% of the tested strains were resistant to cephalosporins (ceftazidime, cefotaxime), β-lactamase/β-lactamase inhibitors (cefoperazone-sulbactam), and carbapenems (meropenem, imipenem). Metallo-β-lactamase and type A broad-spectrum β-lactamase genes were present in 135 and 103 isolates, respectively. The clinical strains in our hospital mainly carried (89.6%, 121/135). Compared with previous studies, these strains had a high rate of resistance to quinolones. The resistance rates to levofloxacin, ciprofloxacin, norfloxacin, gatifloxacin, and nemonoxacin were as high as 83.7-94.8%. The mutations at Ser83Val, Ser83Tyr, and Asp87Gly in the QRDRs of GyrA were significantly related to the resistance of to levofloxacin. All but one quinolone-resistant strain contained at least one significant mutation.

CONCLUSIONS

This study showed a clonal dissemination of isolates in infections at a tertiary care university hospital in Shanghai, China. Minocycline and trimethoprim-sulfamethoxazole had favorable in vitro antibacterial effects. However, the high resistance rate to β-lactams and quinolones was due to carrying β-lactamase ( , ), and mutations in the QRDRs of GyrA.