Api 20e test strips

From June 2017 to June 2018, we collected 1,000 egg samples from farms and markets in Guangdong, China.
Isolation and identification of strains were carried out according to previous reports (Yang et al., 2015). Briefly, each egg was disinfected with 75% alcohol, the shell was carefully removed, and the egg yolks and whites were mixed. Then, 25 g of the sample was added to 225 ml of buffered peptone broth, and 1 ml of the solution was incubated in 10 ml of selenite cystine broth (SC) at 37°C and 10 ml of tetrathionate brilliant green broth (TTB) at 42°C for 24 hr. The SC and TTB cultures were streaked onto xylose–lysine–tergitol 4 (XLT4) selective agar plates and chromogenic Salmonella agar plates (37°C, 24 hr). Presumptive colonies were stabbed into a triple sugar iron slant and incubated at 37°C for 24 hr. Typical Salmonella phenotypes were further confirmed with API 20E test strips (BioMerieux French).

NTS isolates were confirmed using API 20E test strips (bioMerieux, Marcy L’Etoile, France) before serotyping. O and H antigens were characterized using commercial antiserum (S&A Reagents Lab, Bangkok, Thailand) and the serotypes were identified according to Kauffmann-White Scheme [20 ].

Salmonella isolation and identification was performed according to the Standard ISO-6579 (International Organization for Standardization, 2002) method, as described previously (Yang et al., 2010 (link); Ren et al., 2016 (link)) with some modifications. Briefly, 25 g of samples was placed into a sterile plastic bag containing 225 mL of buffered peptone water and shaken for 3 min. The suspension was then cultivated at 37°C in a Shaker at 100 rpm for 6–8 h and then 1 mL of the suspension was added to 10 mL Tetrathionate Broth and Rappaport–Vassiliadis soya broth and incubated at 42°C for 18–24 h, separately. After selective enrichment, the suspensions were streaked onto xylose lysine tergitol 4 agar and CHROMagar^TM incubated at 37°C over night. Isolates with typical Salmonella phenotypes were further confirmed using API 20E test strips (bioMerieux, Marcy-l’Etoile, France).

The S. flexneri strains used in this study were isolated from the fecal samples of patients with diarrhea or dysentery. The fecal samples were screened for Shigella species as follows: samples were streaked onto Salmonella–Shigella (SS) agar and then incubated overnight at 37°C. Suspected Shigella colonies were picked and streaked directly onto SS agar and incubated overnight at 37°C. The resulting colonies were sub-cultured on Luria–Bertani (LB) agar plates and grown in a 37°C incubator. API 20E test strips (bioMérieux Vitek, Marcy-L’Etoile, France) were used for the identification of the Shigella strains following the manufacturer’s recommendations. The specific serotypes of the strains were identified using monovalent antisera (Denka Seiken, Tokyo, Japan).
Informed and written consents were obtained from the patients for sample collection and usage, as well as for the publication of obtained results in this study. All experiments were approved and authorized by the Ethics Committees of the Institute of Disease Prevention and Control, People’s Liberation Army, China.

Metabolic characteristics of bacterial isolates were determined using API 20E test strips (bioMérieux). For inoculation, freshly grown single bacterial colonies were resuspended in sterile distilled water and added to the strips according to the standard protocol provided by the manufacturer. Assay results were documented after 24h and 48h incubation at 36°C. The test was performed twice for isolate IO-23 and once for further Tunisian isolates and internal control strains, i.e. P. heimbachae DSM 3591T, P. vermicola DSM 17385T, P. sneebia DSM 19967T, and P. burhodogranariea DSM 19668T.

A total of 5, 287 Salmonella isolates from foods, patients, and environments in 16 provinces of China were collected between 2002 and 2018. Food sources included chicken, pork, duck, marine products, and frozen food. Human sources included the stool and blood of health checkers, outpatients, and inpatients in hospitals for diarrhea treatment. Environment sources included municipal sewage and poultry feces. All above Salmonella isolates were identified via API20E test strips (bioMérieux, France) and serotyped via commercial antiserum (Statens Serum Institute, Copenhagen, Denmark) according to the manufacturer’s guidelines.

A total of 5, 287 Salmonella isolates from foods, patients, and environments in 16 provinces of China were collected between 2002 and 2018. Food sources included chicken, pork, duck, marine products, and frozen food. Human sources included the stool and blood of health checkers, outpatients, and inpatients in hospitals for diarrhea treatment. Environment sources included municipal sewage and poultry feces. All above Salmonella isolates were identified via API20E test strips (bioMérieux, France) and serotyped via commercial antiserum (Statens Serum Institute, Copenhagen, Denmark) according to the manufacturer’s guidelines.