Delineating the origins of the multidrug-resistant pathogens in ornamental fish farms by multilocus sequence typing and identification of a novel multidrug-resistant plasmid

To evaluate the overuse of antibiotics and to identify the origin of pathogens in the ornamental fish industry, we conducted a field investigation of three representative fish farms in Liaoning province, China. Drug-resistant pathogens in the fishponds and groundwater were isolated and subtyped by multilocus sequence typing (MLST). In total, 33 pathogenic strains, including Aeromonas veronii and five other pathogens, were isolated from diseased fish and from groundwater. MLST revealed that A. veronii obtained from diseased fish in three fish farms can be subtyped into four sequence types, which were also identified in the corresponding groundwater. All of the isolates obtained from diseased fish showed resistance to at least four antibiotics. Notably, Citrobacter freundii JY-17 exhibited resistance to the majority of the antibiotics and was a carrier of a megaplasmid with 15 drug resistance genes. PCR assays targeting β-lactam, kanamycin, macrolide, phenicol, sulfonamide, and trimethoprim resistance genes in the pathogens from the diseased fish and groundwater were also conducted. The results revealed strong correlations between antibiotic treatment and increased antimicrobial resistance in fish pathogens. The results suggested that groundwater is the origin of the pathogens in ornamental fish. Antibiotic treatment of ornamental fish promoted the emergence of resistant pathogens.

Prospective study on the overuse of blood test-guided antibiotics on patients with acute diarrhea in primary hospitals of China

BACKGROUND

Overuse with antibiotics in the treatment of infectious diseases has become a central focus of public health over the years. The aim of this study was to provide an up-to-date evaluation of the blood test-guided antibiotic use on patients with acute diarrhea in primary hospitals of China.

MATERIALS AND METHODS

A cross-sectional survey was conducted on 330 patients with acute diarrhea in Shanghai, People's Republic of China, from March 2013 to February 2016. These patients were treated with or without antibiotics based on the results of their blood tests, including examinations of C-reactive protein (CRP), white blood cells (WBC), and the percentage of neutrophils (Neu%). The infection types, which included bacterial, viral, and combination diarrhea, were determined by microbiological culture methods. Antibiotics used in non-bacterial diarrhea patients were considered misused and overused.

RESULTS

There were significant overall differences in the clinical characteristics and blood tests between patients with diarrhea with a bacterial infection and patients with other types of infections. The patients were divided into four grading groups (0-3) according to the number of the positive results from three blood testes (CRP, WBC, and Neu%). The misuse rates of antibiotics in each group (0-3) were 81.3%, 71.1%, 72.4%, and 64.9%, respectively.

CONCLUSION

In this prospective study, the current diagnostic criteria (CRP, WBC, and Neu%) based on blood tests are not reliable in diagnosing bacterial diarrhea or guiding antibiotics use. To limit antibiotic overuse, a rapid and accurate differentiation of bacterial diarrhea from other types of diarrhea is pivotal.