Prevalence, serotypes, and antimicrobial resistance of Salmonella isolates from patients with diarrhea in Shenzhen, China
Authors: Shen Hong-wei , Chen Haochuan , Ou Yongxuan , Huang Tingting , Ma Wen , Chen Siping , Zhou Lintao , Zhang Jinjin , Hu Qinghua , Zhou Yiwen 
Published: December 2019

Abstract
Background: Salmonella is one of the main causes of diarrhea which causes substantial disease burden. To determine the prevalence, serotype distribution, and antimicrobial resistance profiles of clinical Salmonella isolates in Shenzhen, a 6-year surveillance study was conducted. Methods: Three sentinel hospitals were chosen and patients who visited the gastroenteritis clinics with acute diarrhea were enrolled. Salmonella isolates from the stool samples were subjected to serotyping, antimicrobial susceptibility testing to 24 antibiotics, and detection of resistance genes. Results: A total of 297 (5.7%) Salmonella isolates were recovered from stool samples from 5,239 patients. Among the 42 serovars identified, serovar Typhimurium was the most common serotype which represented 39.7% of the isolates (118), followed by serovar Enteritidis (71, 23.9%), London (12, 4.0%), 4, 5, 12: i: - (11, 3.7%), and Senftenberg (8, 2.7%). A high frequency of resistance was found in ampicillin (70.6%), piperacillin (64.5%), tetracycline (63.5%), and streptomycin (54.3%). Resistance to ampicillin and tetracycline was observed in 95.3% of S. Typhimurium isolates; and nalidixic acid in 93.1% of S. Enteritidis isolates. Resistance to 5 or more antimicrobial agents was identified in 78.8% of S. Typhimurium and 69.0% of S. Enteritidis isolates. Conclusions: Salmonella is an important cause of acute gastroenteritis and a broad range of serotypes are prevalent in Shenzhen, with Enteritidis and Typhimurium being the most common serovars. The high level of antibiotic resistance is a serious public health concern and ongoing monitoring coupled with rational use of antibiotics are recommended.Background: Salmonella is one of the main causes of diarrhea which causes substantial disease burden. To determine the prevalence, serotype distribution, and antimicrobial resistance profiles of clinical Salmonella isolates in Shenzhen, a 6-year surveillance study was conducted. Methods: Three sentinel hospitals were chosen and patients who visited the gastroenteritis clinics with acute diarrhea were enrolled. Salmonella isolates from the stool samples were subjected to serotyping, antimicrobial susceptibility testing to 24 antibiotics, and detection of resistance genes. Results: A total of 297 (5.7%) Salmonella isolates were recovered from stool samples from 5,239 patients. Among the 42 serovars identified, serovar Typhimurium was the most common serotype which represented 39.7% of the isolates (118), followed by serovar Enteritidis (71, 23.9%), London (12, 4.0%), 4, 5, 12: i: - (11, 3.7%), and Senftenberg (8, 2.7%). A high frequency of resistance was found in ampicillin (70.6%), piperacillin (64.5%), tetracycline (63.5%), and streptomycin (54.3%). Resistance to ampicillin and tetracycline was observed in 95.3% of S. Typhimurium isolates; and nalidixic acid in 93.1% of S. Enteritidis isolates. Resistance to 5 or more antimicrobial agents was identified in 78.8% of S. Typhimurium and 69.0% of S. Enteritidis isolates. Conclusions: Salmonella is an important cause of acute gastroenteritis and a broad range of serotypes are prevalent in Shenzhen, with Enteritidis and Typhimurium being the most common serovars. The high level of antibiotic resistance is a serious public health concern and ongoing monitoring coupled with rational use of antibiotics are recommended.