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Molecular sequence typing reveals genotypic diversity among Escherichia coli isolates recovered from a cantaloupe packinghouse in Northwestern Mexico
Author(s) -
Quiñones B.,
Campos Sauceda J.P.,
Lee B.G.,
Yambao J.C.,
Cháidez Quiroz C.
Publication year - 2017
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12733
Subject(s) - multilocus sequence typing , biology , phylogenetic tree , genotype , escherichia coli , typing , genetic diversity , genetics , population , gene , demography , sociology
The increase in the consumption of fresh produce has correlated with a rise in the number of reported foodborne illnesses. To identify potential risk factors associated with postharvest practices, the present study employed multilocus sequence typing ( MLST ) for the genotypic classification of Escherichia coli isolates recovered from three sources sampled at seven operational stages in a cantaloupe packinghouse in Northwestern Mexico. The MLST analysis results indicated that the E . coli isolates were classified into 18 different sequence types ( ST ), and 11 of these ST s were found to be novel. ST ‐171 was the predominant type and was found in 19% (7/36) of the recovered isolates. Interestingly, the novel ST ‐827 was found to be significantly associated with isolates recovered from workers’ hands, sampled during final postwash stages. Further phylogenetic analyses to examine the relatedness of the ST s revealed genetic heterogeneity. Fourteen of the identified ST s were assigned to known clonal groups, while the remaining four novel ST s were distinct and did not cluster with any clonal group. The present study has provided the first evidence indicating that several sources from distinct operational stages in a cantaloupe packinghouse may contribute to a genotypic and phylogenetic diverse set of E . coli isolates. Significance and Impact of the Study Packinghouses can be considered as a potential source of microbial contamination. Using multilocus sequence typing, this study identified a genotypic and phylogenetic diverse set of Escherichia coli isolates recovered from the surfaces of cantaloupes, workers’ hands and processing equipment at a cantaloupe packinghouse. A total of 61% of the sequence types identified were novel, and a distinct sequence type, ST ‐827, was significantly associated with worker's hands, sampled during the final postwash operational stages in the packinghouse. These findings serve as a baseline to identify potential sources of microbial contamination at distinct operational stages in a cantaloupe packinghouse.