Behavior of non-O157 Shiga toxin-producing Escherichia coli, enteroinvasive E. Coli, enteropathogenic E. Coli, and enterotoxigenic E. coli strains on alfalfa sprouts

Data about the behavior of non-O157 Shiga toxin-producing Escherichia coli (non-O157 STEC), enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC), and enteropathogenic E. coli (EPEC) on seeds and alfalfa sprouts are not available. The behavior of STEC, EIEC, ETEC, and EPEC was determined during germination and sprouting of alfalfa seeds at 20 Zapotitlán 2°C and 30 Zapotitlán 2°C and on alfalfa sprouts at 3 Zapotitlán 2°C. When alfalfa seeds were inoculated with STEC, EIEC, ETEC, or EPEC strains, all these diarrheagenic E. coli pathotypes (DEPs) grew during germination and sprouting of seeds, reaching counts of approximately 5 and 6 log CFU/g after 1 day at 20 Zapotitlán 2°C and 30 Zapotitlán 2°C, respectively. However, when the sprouts were inoculated after 1 day of seed germination and stored at 20Zapotitlán2°C or 30Zapotitlán2°C, no growth was observed for any DEP during sprouting at 20Zapotitlán2°C or 30 Zapotitlán 2°C for 9 days. Refrigeration reduced significantly (P < 0.0.5) the number of viable DEPs on sprouts after 20 days in storage; nevertheless, these decreases have no practical significance for the safety of the sprouts. Copyright Zapotitlán International Association for Food Protection

Structural characteristics of gels formed by mixtures of carrageenan and mucilage gum from Opuntia ficus indica

Sol-gel and gel-sol transitions of mixtures formed by mucilage gum from Opuntia ficus indica and either K-carrageenan or L-carrageenan were studied using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). A total polymer concentration of 2% (w/w), a mucilage concentration in the interval between 0 and 80% (w/w), and KCl or CaCl2 concentrations of 12 or 60 mM, were used. Results from DSC showed that gelation was independent of the presence of mucilage gum in the mixtures. SEM results showed the non-gelling characteristic of mucilage gum from O.ficus indica. However, when mixed with K-carrageenan a synergistic effect was observed only at (he 80/20 kappa-carrageenan/mucilage gum ratio. The DSC and SEM results indicated that the mucilage gum gets adsorbed onto the i-carrageenan structure in an interaction controlled by electrostatic charges. Regarding the i-carradeenan/mucilage mixtures no clear interaction at structural level was observed. (c) 2005 Published by Elsevier Ltd

Presence of some indicator bacteria and diarrheagenic E. coli pathotypes on jalapeño and serrano peppers from popular markets in Pachuca City, Mexico

The chili pepper is a very important crop in Mexico. Diarrheagenic E. coli pathotypes (DEPs) are important foodborne pathogens in different countries including Mexico. No data exists on DEPs presence on fresh jalapeño and serrano pepper and little data have been published on the microbiological quality of these peppers. The frequencies of coliform bacteria (CB), thermotolerant coliforms (TC), E. coli and DEPs were determined for jalapeño and serrano peppers. Of 100 serrano samples, CB, TC, E. coli and DEPs were identified in 100, 90, 58 and 36%, respectively. Of 100 jalapeño samples, CB, TC, E. coli and DEPs were identified in 100, 88, 38 and 14%, respectively. Identified DEPs included enterotoxigenic E. coli (ETEC) and Shiga toxin-producing E. coli (STEC). STEC were isolated from 36% of serrano samples and 14% of jalapeño samples. ETEC were isolated from 12% of serrano samples and 2% of jalapeño samples. Both STEC and ETEC were identified in 14 serrano samples and 2 jalapeño samples. No E. coli O157:H7 were detected in any STEC-positive samples. Jalapeño and serrano peppers could be an important factor contributing to the endemicity of DEPs-caused gastroenteritis in Mexico. © 2012 Elsevier Ltd

Behaviour of four diarrheagenic Escherichia coli pathotypes on carrots and in unpasteurized carrot juice

The behaviours of Shiga toxin-producing Escherichia coli (STEC), enteroinvasive E.\ua0coli (EIEC), enteropathogenic E.\ua0coli (EPEC) and enterotoxigenic E.\ua0coli (ETEC) strains on raw carrots at 3\ua0±\ua01 and 30\ua0±\ua01°C, and in unpasteurized carrot juice at 3\ua0±\ua01, 12\ua0±\ua01, 20\ua0±\ua01, 30\ua0±\ua01°C and 37\ua0±\ua01°C were determined. Raw carrots were purchased in a local market. Fresh juice was obtained from raw carrots in the laboratory. On whole carrots stored at 30\ua0±\ua01 or 3\ua0±\ua01°C, no growth was observed for any of the diarrheagenic E.\ua0coli pathotype (DEPs) strains studied. After 15\ua0days at 30\ua0±\ua01°C, the tested DEPs had decreased from an initial inoculum level of approximately 6 log colony-forming units (CFU) to approximately 3·5 log CFU on whole carrots, while at 3\ua0±\ua01°C, they decreased from approximately 2·4 log to 1·6 log CFU. All these DEPs grew in fresh carrot juice at 12\ua0±\ua01, 20\ua0±\ua01, 30\ua0±\ua01 and 37\ua0±\ua01°C, reaching counts of approximately 4·2 log, 5·8 log, 6·7 log and 7·5 log CFU\ua0ml-1, respectively, after 24\ua0h. At 3\ua0±\ua01°C, the DEP growth was inhibited at least during 7\ua0days. Thus, storage of carrot juice at unrefrigerated temperatures can result in DEP growth to levels likely to represent a risk to consumers. © 2013 The Society for Applied Microbiology

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

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 &lt;3 to 1100 MPN ml-1 and &lt;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

Presence and correlation of some enteric indicator bacteria, diarrheagenic escherichia coli pathotypes, and salmonella serotypes in alfalfa sprouts from local retail markets in Pachuca, Mexico

Data on the presence of diarrheagenic Escherichia coli pathotypes (DEPs) in alfalfa sprouts and correlations between the presence of coliform bacteria (CB), fecal coliforms (FC), E. coli, DEPs, and Salmonella in alfalfa sprouts are not available. The presence of and correlations between CB, FC, E. coli, DEPs, and Salmonella in alfalfa sprouts were determined. One hundred sprout samples were collected from retail markets in Pachuca, Hidalgo State, Mexico. The presence of indicator bacteria and Salmonella was determined using conventional culture procedures. DEPs were identified using two multiplex PCR procedures. One hundred percent of samples were positive for CB, 90% for FC, 84% for E. coli, 10% for DEPs, and 4% for Salmonella. The populations of CB ranged from 6.2 up to 8.6 log CFU/g. The FC and E. coli concentrations were between <3 and 1,100 most probable number (MPN)/g. The DEPs identified included enterotoxigenic E. coli (ETEC; 2%), enteropathogenic E. coli (EPEC; 3%), and Shiga toxin-producing E. coli (STEC; 5%). No E. coli O157:H7 strains were detected in any STEC-positive samples. In samples positive for DEPs, the concentrations ranged from 210 to 240 MPN/g for ETEC, 28 to 1,100 MPN/g for EPEC, and 3.6 to 460 MPN/g for STEC. The Salmonella isolates identified included Salmonella enterica serotype Typhimurium in three samples and Salmonella enterica serotype Enteritidis in one. STEC and Salmonella Typhimurium were identified together in one sample. Positive correlations were observed between FC and E. coli, between FC and DEPs, and between E. coli and DEPs. Negative correlations occurred between CB and DEPs and between CB and Salmonella. Neither FC nor E. coli correlated with Salmonella in the sprout samples. To our knowledge, this is the first report of ETEC, EPEC, and STEC isolated from alfalfa sprouts and the first report of correlations between different indicator groups versus DEPs and Salmonella. © International Association for Food Protection

Presence of Shiga toxin-producing Escherichia coli, Enteroinvasive E. coli, Enteropathogenic E. coli, and Enterotoxigenic E. coli on tomatoes from public markets in Mexico

Diarrheagenic Escherichia coli pathotypes (DEP) are important foodborne pathogens in various countries, including Mexico. However, no data exist on the presence of DEP on fresh tomatoes (Solanum lycopericum) from Mexico. The frequency of fecal coliforms (FC), E. coli, and DEP were determined for two tomato varieties. One hundred samples of a saladette tomato variety and 100 samples of a red round tomato variety were collected from public markets in Pachuca, Mexico. Each tomato sample consisted of four whole tomatoes. For the 100 saladette samples, coliform bacterial, FC, E. coli, and DEP were identified in 100, 70, 60, and 10% of samples, respectively. For the 100 red round samples, coliform bacterial, FC, E. coli, and DEP were identified in 100, 75, 65, and 11% of samples, respectively. Identified DEP included Shiga toxin-producing E. coli (STEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC). STEC were isolated from 6% of saladette samples and 5% of red round samples. ETEC were isolated from 3% of saladette samples and 4% of red round samples. EPEC were isolated from 2% of saladette samples and 3% of red round samples, and EIEC were isolated from 1% of saladette samples. Both STEC and ETEC were identified in two saladette samples and 1 red round sample. E. coli O157:H7 was not detected in any STEC-positive samples. Copyright © 2013, International Association for Food Protection

Acid and alcohol tolerance of Escherichia coli O157:H7 in pulque, a typical Mexican beverage

Pulque is a traditional Mexican fermented alcoholic beverage produced from the nectar of maguey agave plants. No data exist on the behavior of Escherichia coli O157:H7 in agave nectar and pulque. An initial trial was done of the behavior of E. coli O157:H7 during fermentation of nectar from a single producer, a nectar mixture from different producers and "seed" pulque. A second trial simulating artisanal pulque production was done by contaminating fresh nectar with a cocktail of three E. coli O157:H7 strains, storing at 16° and 22°C for 14. h, adding seed pulque and fermenting until pulque was formed. A third trial used pulque from the second trial stored at 22°C as seed to ferment fresh nectar at 22°C for 48. h (fermentation cycle). This procedure was repeated for an additional two fermentation cycles. During incubation at 16° or 22°C in the first trial, the E. coli O157:H7 strains multiplied in both the single producer nectar and nectar mixture, reaching maximum concentration at 12. h. E. coli O157:H7 cell concentration then decreased slowly, although it survived at least 72. h in both fermented nectars. E. coli O157:H7 did not multiply in the seed pulque but did survive at least 72. h. In the second trial, the numbers of E. coli O157:H7 increased approximately 1.5. log. CFU/ml at 22°C and 1.2. log. CFU/ml at 16°C after 14. h. After seed pulque was added, E. coli O157:H7 concentration decreased to approximately 2. log. CFU/ml, and then remained constant until pulque was produced. In the third trial, the E. coli O157:H7 cells multiplied and survived during at least three nectar fermentation cycles. The results suggest that E. coli O157:H7 can develop acid and alcohol tolerance in pulque, and constitutes a public health risk for pulque consumers. © 2011 Elsevier B.V

Preparation of silver nanostructures from bicontinuous microemulsions

Data on the presence of diarrheagenic Escherichia coli pathotypes (DEPs) in alfalfa sprouts and correlations between the presence of coliform bacteria (CB), fecal coliforms (FC), E. coli, DEPs, and Salmonella in alfalfa sprouts are not available. The presence of and correlations between CB, FC, E. coli, DEPs, and Salmonella in alfalfa sprouts were determined. One hundred sprout samples were collected from retail markets in Pachuca, Hidalgo State, Mexico. The presence of indicator bacteria and Salmonella was determined using conventional culture procedures. DEPs were identified using two multiplex PCR procedures. One hundred percent of samples were positive for CB, 90% for FC, 84% for E. coli, 10% for DEPs, and 4% for Salmonella. The populations of CB ranged from 6.2 up to 8.6 log CFU/g. The FC and E. coli concentrations were between <3 and 1,100 most probable number (MPN)/g. The DEPs identified included enterotoxigenic E. coli (ETEC; 2%), enteropathogenic E. coli (EPEC; 3%), and Shiga toxin-producing E. coli (STEC; 5%). No E. coli O157:H7 strains were detected in any STEC-positive samples. In samples positive for DEPs, the concentrations ranged from 210 to 240 MPN/g for ETEC, 28 to 1,100 MPN/g for EPEC, and 3.6 to 460 MPN/g for STEC. The Salmonella isolates identified included Salmonella enterica serotype Typhimurium in three samples and Salmonella enterica serotype Enteritidis in one. STEC and Salmonella Typhimurium were identified together in one sample. Positive correlations were observed between FC and E. coli, between FC and DEPs, and between E. coli and DEPs. Negative correlations occurred between CB and DEPs and between CB and Salmonella. Neither FC nor E. coli correlated with Salmonella in the sprout samples. To our knowledge, this is the first report of ETEC, EPEC, and STEC isolated from alfalfa sprouts and the first report of correlations between different indicator groups versus DEPs and Salmonella. " International Association for Food Protection.",,,,,,"10.4315/0362-028X.JFP-14-229",,,"http://hdl.handle.net/20.500.12104/43833","http://www.scopus.com/inward/record.url?eid=2-s2.0-84923828231&partnerID=40&md5=c0aa6359a10dc78c84b5ecc1e2e4672