AUTHORS
Zhan Z, Xu X, Gu Z, Meng J, Wufuer X, Wang M, Huang M, Chen J, Jing C, Xiong Z, Zeng M, Liao M, Zhang J
ABSTRACT
INTS isolates were recovered from blood and other clinical specimens collected during 2007-2016 across five provinces (Shanghai, Xinjiang, Fujian, Guangxi, and Chongqing) in China. Antimicrobial susceptibility was performed using the agar dilution method and molecular epidemiology was performed using standard microbiological techniques. A total of 178 iNTS isolates were recovered from approximately 9700 patient specimens during 2007-2016. The predominant serovars were Salmonella Enteritidis (57/178, 32%), Salmonella Choleraesuis (47/178, 26.4%), and Salmonella Typhimurium (24/178, 13.5%). Up to 50 isolates (28.1%) were from patients who were ≤1 year of age, while 28 (15.7%) were from patients who were ≥60 years. Among these isolates, high rates of resistance to nalidixic acid (114/178, 64%), sulfisoxazole (59%), ciprofloxacin (15.2%), and cefotaxime (8.4%) were found. Moreover, 53.4% (95/178) exhibited multidrug resistance, and 3.9% (7/178) showed co-resistance to third-generation cephalosporins and ciprofloxacin. Steadily increasing numbers of nalidixic acid, cefotaxime, and ciprofloxacin-resistant isolates, but decreasing numbers of multidrug resistance isolates were detected during the study period. Detection of quinolone genes in 114 nalidixic acid-resistant isolates showed that 58.3% (67/114) harbored plasmid-mediated quinolone resistance (PMQR) genes [aac(6´)-Ib-cr, qnrA, qnrB, oqxAB, qepA, qnrS, and qnrD] and 98.2% (112/114) exhibited mutations in quinolone resistance determining regions [gyrA, parC, and parE]. Furthermore, we detected beta-lactamases genes in the ceftriaxone-resistant isolates. The most common were blaTEM-1 (93.3%), followed by blaCTX-M-55 (40%), blaCMY-2 (33.3%), and blaOXA-1 (33.3%). Finally, a range of pulsed-field gel electrophoresis patterns were detected among the Salmonella Enteritidis and Salmonella Typhimurium isolates. High rates of multidrug resistance and steadily increasing cefotaxime and ciprofloxacin-resistant iNTS could pose a significant challenge for the effective treatment of salmonellosis in China.
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