METHODS: Tennessee submits to NARMS every 20thhuman NTS isolate detected statewide and all NTS isolates from retail meat purchased from 4 counties. Broth microdilution is performed to determine minimum inhibitory concentrations for 14 antimicrobials (8 classes). Resistance patterns among human isolates were compared to those in retail meats. Analysis was done using Epi Info 7.
RESULTS: From 2010 through 2013, 179 sporadic NTS human isolates and 76 NTS retail meat isolates were tested. Twenty-two (12%) NTS human isolates and 54 (71%) NTS retail meat isolates demonstrated AR. AR to ≥ 3 classes was detected in 13 (7%) NTS human isolates, 6 (18%) chicken breast isolates, and 14 (45%) ground turkey. Four (2%) human isolates were resistant only to ampicillin, chloramphenicol, sulfisoxazole, streptomycin, and tetracycline (ACSSuT); all were serotype Typhimurium. Resistance to quinolones was detected in 2 (1%) human isolates; serotypes Typhimurium and Litchfield. Only 1 (0.6%) of NTS human isolates was resistant to ceftriaxone compared to 2 (6%) and 5 (16%) from chicken breast and ground turkey isolates, respectively. Ceftriaxone-resistant human, chicken, and turkey isolates were differing serotypes and two of them also demonstrated ACSSuT resistance. No retail meat isolates were quinolone resistant.
CONCLUSIONS: AR is a public health concern. In Tennessee, AR NTS human isolates occurred less commonly than some national estimates, particularly AR to CIAs. Retail meat isolates demonstrated AR more frequently than human NTS with ground turkey isolate AR being more common than chicken. Serotypes varied among AR isolates from all 3 sources. Expansion of NARMS sampling statewide could provide a better understanding of attribution of human AR NTS infections to their source.