Presence of indicator bacteria, diarrhoeagenic Escherichia coli pathotypes and Salmonella in fresh carrot juice from Mexican restaurants

Abstract

Coliform bacteria (CB), faecal coliforms (FC), Escherichia coli, diarrhoeagenic E.coli pathotypes (DEP) and Salmonella frequencies were determined for fresh carrot juice from restaurants in Pachuca city, Mexico. Two hundred and eighty carrot juice samples were purchased in three types of restaurants: (A), national chain restaurants; (B), local restaurants; and (C), very small restaurants. Two restaurants for each A and B, and three for C, were included. Forty juice samples were purchased at each restaurant. All tested juice samples had poor microbiological quality. Of these samples, 100, 96·8, 54·3, 8·9 and 8·6% had CB, FC, E.coli, DEP and Salmonella, respectively. CB were present in all juice samples regardless of source, with limits ranging from 3·6×102 to 8·5×107 CFU ml-1, and the limits for FC and E.coli were <3 to 1100 MPN ml-1 and <3 to 460 MPN, respectively. DEP and Salmonella were isolated from samples from all the restaurants at levels of 5% or above: DEP, 5% (A1, B2), 10% (A2, B1, C1, C2) and 12·5% (C3); Salmonella, 5% (A1, A2, B2), 7·5% (C2), 10% (C1), 12·5% (B1) and 15% (C3). Significance and Impact of the Study: This is the first report of microbiological quality and Salmonella, enteroinvasive E.coli (EIEC), enterotoxigenic E.coli (ETEC) and Shiga toxin-producing E.coli (STEC) isolation from fresh carrot juice in Mexico. Fresh carrot juice from restaurants could be an important factor contributing to the endemicity of EIEC-, ETEC- and STEC- and Salmonella-caused gastroenteritis in Mexico. © 2012 The Society for Applied Microbiology.