Surveillance and drug resistance analysis of Salmonella in Guangdong province in 2015

Abstract

Objective To analyze the serotype distribution and antibiotic resistance characteristics of Salmonella strains isolated in Guangdong province for better understanding the condition of Salmonella infection in patients with diarrhea. Methods Fecal samples collected from patients with diarrhea in Guangdong province were used to isolate Salmonella strains. Biochemical analysis was performed to identify these isolated strains. Serotyping and antimicrobial susceptibility testing were carried out for further analysis of the isolated Salmonella strains. Results The rate of Salmonella infection was 7.64%in 2015, and the male to female patient ratio was 1.52∶1. A total of 2 377 patients of all age groups were positive for Salmonella infection and the patients aged 0-6 years accounted for 81.74%. The isolation rate of Salmonella strains in the summer and autumn was higher than that in the winter and spring (10.73% vs 4.24%; χ2=463.77, P<0.01). The Salmonella isolation rates in different areas were as follows: 16.82% in Zhuhai, 15.85% in Heyuan, 11.81% in Yangjiang, 10.68% in Jiangmen, 8.49% in Zhongshan, 8.07% in Maoming, 8.05% in Jieyang, 7.35% in Shaoguan, 6.97% in Foshan, 6.03% in Dongguan, 5.48% in Guangzhou and 0.00% in Zhanjiang. And the differences between different regions were statistically significant (χ2=367.67, P<0.01). The 2 377 isolated Salmonella strains were classified into 108 serotypes except for oneSalmonella strain that could not be classified. The top four predominant serotypes were 4, 5, 12: i: -, Salmonella enteritidis, Salmonella stanley and Salmonella typhimurium. Most Salmonella strains were sensitive to imipenem, azithromycin, ceftazidime, cefotaxime and trimethoprim/sulfamethoxazole, but multidrug resistance was common among those strains. Conclusion Salmonella serotypes of 4, 5, 12: i: - and Salmonella enteritidis are the predominant pathogens causing human Salmonella infections in Guangdong province. Ceftazidime and cefotaximeare are preferred in the treatment of Salmonella infections. Surveillance for drug resistance in Salmonella should be strengthened as multidrug resistant strains have become a serious problem in Guangdong province. Key words: Salmonella; Multidrug resistance; Antibiotic resistance surveillance