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Salmonella enterica serovar Stanley is an important serovar that has been increasingly identified in human salmonellosis. The present study aimed to investigate the antimicrobial resistance and molecular typing of 88 Salmonella Stanley strains isolated from humans (diarrhea patients, n = 64; and healthy carrier, n = 1), foods (aquatic products, n = 16; vegetable, n = 1; and pork, n = 1), and environment (waste water, n = 2; and river water, n = 3) in Shanghai, China from 2006 to 2012. Nearly half of the strains were resistant to sulfafurazole (43/88, 48.9%), and many were resistant to streptomycin (35/88, 39.8%), tetracycline (22/88, 25%), and nalidixic acid (19/88, 21.6%). Approximately a quarter of the strains (24/88, 27.3%) were resistant to more than three antimicrobials, and five had ACSSuT resistance type. Six clusters (A-F) were identified by pulsed-field gel electrophoresis (PFGE) with 80% similarity. Interestingly, strains in the same cluster identified by PFGE possessed similar antibiotic resistance patterns. PFGE typing also indicated that aquatic products might serve as a transmission reservoir for Salmonella Stanley infections in humans.

Diarrheagenic Escherichia coli (DEC) is a major cause of bacterial gastroenteritis in children. Also, antibiotic resistance among DEC is becoming a critical area of concern in clinical settings.This study was conducted in 4 hospitals in Shanghai from June 2012 to October 2013. DEC isolates from stool samples of patients with diarrhea were examined to determine their antimicrobial susceptibilities and presence of virulence genes, in order to identify high risk clones.A total of 735 (10.2%) DEC isolates were identified from 7204 stool samples from patients with diarrhea, including 374 enteropathogenic E. coli, 318 enterotoxigenic E. coli, 36 Shigella/enteroinvasive E. coli and 7 Shiga toxin-producing E. coli (STEC). Among the 735 DEC isolates, 299 (40.7%) were isolated from children less than 5 years old. High resistance rates were observed to streptomycin (90.7%), ampicillin (63.4%), nalidixic acid (61.1%), sulfisoxazole (49.1%), tetracycline (41.2%), trimethoprim (35.6%), trimethoprim-sulfamethoxazole (35.4%), followed by amoxicillin-clavulanic acid (27.2%), cefotaxime (24.5%), cefepime (23.5%), gentamicin (16.7%), ceftazidime (12.4%), chloramphenicol (10.6%), ciprofloxacin (7.2%) and ofloxacin (3.4%). All the isolates were susceptible to imipenem. In addition, potential virulence genes were screened by polymerase chain reaction. A total of 15 enterotoxigenic E. coli belonging to the same clone were identified to be associated with nosocomial neonatal diarrhea and resistant to greater than 10 antimicrobials.Our findings suggest that active surveillance programs combining both phenotypic and genetic data would help identify disease outbreaks and strengthen antibiotic management.

Salmonella enterica serotype Agona (Salmonella Agona) has been among the top 10 serotypes that cause human diarrheal diseases in China. A total of 95 Salmonella Agona (67 from humans, and 28 from animals, food of animal origins, and environmental sources) recovered in Shanghai, China from 2005 to 2011 were subjected to antimicrobial susceptibility testing and molecular subtyping using pulsed-field gel electrophoresis (PFGE). Approximately 68.4% of the Salmonella Agona isolates were pansusceptible to 15 antimicrobial agents tested, and 4 isolates (4.21%) were resistant to at least 3 antimicrobials. PFGE analysis resulted in 41 unique patterns, of which 4 major PFGE patterns (X3, X4, X5, and X6) were grouped together at 96.1% similarity. Isolates of the four patterns included those from food (pork, beef, and chicken) and humans. Our findings showed that the same clones of Salmonella Agona were recovered from human patients and food, and that food of animal origin was potentially a major vehicle of Salmonella Agona in human salmonellosis in Shanghai.

A total of 123 enterotoxigenic Escherichia coli (ETEC) isolates from diarrheal patients from June to December 2012 in Shanghai, China, were examined to determine their genetic relatedness using multilocus sequence typing and pulsed-field gel electrophoresis (PFGE) and for the presence of virulence genes and antimicrobial susceptibility. Twenty-nine sequence types (STs) and 63 PFGE patterns were identified, and results from the 2 subtyping methods correlated well. The 12 isolates of PFGE cluster B all belonged to ST-2332 and were associated with nosocomial neonatal diarrhea. Isolates of a cluster usually had the same set of virulence factors, whereas isolates of different PFGE clusters carried diverse combinations of virulence determinants. Isolates belonging to ST-2332 and ST-182 (n=9) were resistant to at least 6 antimicrobials. Our findings highlighted the need of active surveillance programs for infectious diseases collecting data at both epidemiological and genetic levels that can detect high-risk lineages of pathogens in order to rapidly identify disease outbreaks.