A comparison of methods to detect low levels of Salmonella enterica in surface waters to support antimicrobial resistance surveillance efforts performed in multiple laboratories

• Published in: The Science of the total environment 2023-12, Vol.905, p.167189-167189, Article 167189
• Main Authors: Kraft, Autumn L., Wells, Jim E., Frye, Jonathan G., Ibekwe, Abasiofiok M., Durso, Lisa M., Hiott, Lari, East, Cheryl, McConn, Betty R., Franklin, Alison M., Boczek, Laura A., Garland, Jay L., Kabera, Claudine, McDermott, Patrick F., Ottesen, Andrea R., Zheng, Jie, Cook, Kimberly L., Sharma, Manan
• Format: Article
• Language: English
• Subjects: Antibiotic resistance; Detection; Filtration; Methods; Salmonella; Water
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.167189

Developing effective and sensitive detection methods for antimicrobial resistant Salmonella enterica from surface water is a goal of the National Antimicrobial Resistance Monitoring System (NARMS). There are no specified methods for recovery of S. enterica in surface waters in the U.S. A multi-laboratory evaluation of four methods - bulk water enrichment (BW), vertical Modified Moore Swab (VMMS), modified Standard Method 9260.B2 (SM), and dead-end ultrafiltration (DEUF) – was undertaken to recover S. enterica from surface water. In Phase 1, one-liter volumes of water were collected from the same site on five different dates. Water was shipped and analyzed at four different laboratory locations (A, B, C, and D) for recovery of 1) inoculated fluorescent S. Typhimurium strain (ca. 30 CFU/L) and 2) Salmonella present in the water sampled. At each location, BW, VMMS, or SM recovery was performed on five separate 1 L water samples. Twenty 1 L water samples were subjected to each recovery method, and overall, sixty 1 L samples were assayed for Salmonella. Inoculated, fluorescent Salmonella Typhimurium and environmental Salmonella spp. were recovered from 65 % (39/60) and 45 % (27/60) of water samples, respectively. BW, VMMS, and SM recovered fluorescent S. Typhimurium from 60 %, 60 %, and 75 % of inoculated samples, respectively. Analysis by Chi-squared test determined laboratory location had a significant (p  0.05) did not affect Salmonella recovery. Uniform laboratory methodology and training should be prioritized in conducting Salmonella recovery from surface water in laboratories. [Display omitted] •Four different laboratories compared four different methods to recover inoculated S. enterica from surface water.•Laboratory location influenced recovery of S. Typhimurium more than method or date.•Modified standard method 9260.B2, vertical modified Moore Swab, and Bulk Water recovered S. Typhimurium at similar levels.•Modified standard method 9260.B2 and dead-end ultrafiltration recovered statistically similar levels of S. Typhimurium.