[The first identification of epidemic clone of enterotoxic Escherichia coli O∶6 serogroup highly associated with azithromycin resistance in Shanghai].

Objective: To investigate the molecular characterization of adult diarrhea cases caused by enterotoxic Escherichia coli (ETEC) and explore the practical model of epidemiology for laboratory technique and data needs based on the surveillance network. Methods: Epidemiological design and sampling targeted adult cases ETEC caused diarrhea in epidemic season. The enterotoxin type, serogroup, resistance, colonization factor and molecular type of ETEC were identified. Multiple dynamic phenotypic characteristics of ETEC were indicated by multidimensional and multivariable data. Results: From 2016 to 2018, 84 eligible ETEC strains were detected. The dominant serums/toxins were O∶6 (STh), O∶25 (LT), O∶159 (STh), O∶153 (STh). O∶6 (STh+CS21), which replaced O∶25 and O∶159 as the popular clones in 2018. Six cases of O∶153 (STh+CFA/I+CS8+PT34) in outbreak in 2017 were imported ones. The resistance rates of ETEC strains detected in adults to sulfasoxazole, naproxinic acid, ampicillin and azithromycin were more than 30%, multidrug resistance (MDR) reached 58.3%. Serum/toxin types suggested that attenuated strains were more likely to become MDR. Molecular typing confirmed that the genetic similarity of the dominant clone of O∶6 serogroup (PT20-24) was higher than O∶25 and O∶159. There was a high correlation between the minimal inhibitory concentration (MIC) of azithromycin and the resistant gene mphA (87.5%, 28/32). O∶6 (STh+CS21+mphA) resistant clone was first detected in 2016. Conclusion: A new epidemic clone in adult ETEC diarrhea cases in Shanghai was O∶6 (STh+CS21+mphA). For the first time the association between azithromycin resistance gene mphA and a serum group of ETEC was observed. Multidimensional and multivariate analysis techniques based on epidemiology can help reveal the potential transmission pattern of ETEC for the accurate surveillance and early warning of outbreaks.

Composição química e concentração mínima bactericida de dezesseis óleos essenciais sobre Escherichia coli enterotoxigênica / Determination of minimum bactericidal concentration of sixteen essential oils on enterotoxigenic Escherichia coli

RESUMO Este trabalho teve por objetivo avaliar o efeito bactericida in vitro de dezesseis óleos essenciais sobre Escherichia coli enterotoxigênica (ETEC). Dentre os óleos essenciais estudados, três foram extraídos in situ por arraste a vapor e treze foram adquiridos comercialmente. Todos os óleos foram analisados por CG-EM e CG-DIC. A atividade bactericida foi avaliada pelo método de microdiluição utilizando-se caldo triptona de soja e microplacas de poliestireno de 96 poços, com posterior plaqueamento das culturas em ágar triptona de soja. Os óleos essenciais de Cinnamomum cassia e de Thymus vulgaris apresentaram concentração mínima bactericida (CMB) de 0,12% e 0,25%, respectivamente. Já os óleos comerciais de Syzygium aromaticum e Origanum vulgare apresentaram ambos CMB de 0,50% e os óleos extraídos in situ de Cymbopogon citratus e Origanum vulgare apresentaram ambos CMB de 1,00%. Os dezesseis óleos essenciais apresentaram composição química qualitativa e quantitativa distintas. As análises químicas dos óleos essenciais de Cinnamomum cassia e de Thymus vulgaris tiveram a presença majoritária de E-cinamaldeído (84,52%) e timol (50,89%). Conclui-se que os óleos de C. cassia e T. vulgaris foram os mais eficazes na inibição do crescimento in vitro dessa bactéria, a qual possui diferentes níveis de sensibilidade dependendo da composição química do óleo.

ABSTRACT This study aimed to evaluate the bactericidal effect in vitro of sixteen essential oils on enterotoxigenic Escherichia coli (ETEC). Among the essential oils, three were extracted in situ by steam distillation and thirteen were purchased commercially. All oils were analyzed by GC-MS and GC-FID. The bactericidal activity was evaluated by the microdilution method using tryptone soy broth, and 96-well polystyrene microplates with subsequent plating of the cultures in tryptone soy agar. Cinnamomum cassia and Thymus vulgaris essential oils showed minimal bactericidal concentration (MBC) 0.12% and 0.25%, respectively. Both commercial oils of Syzygium aromaticum and Origanum vulgare showed MBC of 0.50% and the oils extracted in situ Origanum vulgare and Cymbopogon citratus showed both MBC of 1.00%. The sixteen essential oils pointed out distinct qualitative and quantitative chemical composition. Chemical analysis of Cinnamomum cassia and Thymus vulgaris oils had the predominant presence of E-cinnamaldehyde (84.52% ± 0.07%) and thymol (50.89% ± 0.31%). In conclusion, T. vulgaris and C. cassia oils were the most effective in inhibiting in vitro growth of this bacterium, which has different sensitivity levels depending on the chemical composition of the oil.

A standardised challenge model with an enterotoxigenic F4+ Escherichia coli strain in piglets assessing clinical traits and faecal shedding of fae and est-II toxin genes.

This study evaluated the effect of five feed additives on post weaning diarrhoea (PWD) in piglets challenged 3 d after weaning with an enterotoxigenic Escherichia coli strain (ETEC). In three experimental runs, a total of 84 piglets was weaned at 21 days of age and randomly assigned to seven treatments. As dietary treatment, piglets were fed a basal diet or diets with addition of bovine colostrum (0.2%), pineapple stem extract containing bromelain (0.2%), an autolysed yeast preparation (Saccharomyces cerevisiae) (0.1%), a combination of organic acids (0.7%) and a phytogenic product with thyme essential oil (0.015%). A porcine ETEC, serotype O149:K91:K88ac was given twice via oral infection on day 3 after weaning at 10(10) colony forming units/animal. One group of piglets was fed the basal diet without ETEC challenge. Traits included clinical sores, body temperature, faecal scoring and determination of faecal dry matter and the shedding of fae and est-II ETEC toxin genes. After weaning, non-challenged control piglets did not show signs of diarrhoea or impaired health, while the majority of infected piglets had a drop in body temperature, signs of diarrhoea and impaired general health. Mortality, the decrease of faecal dry matter and shedding of the toxin genes fae and est-II were not affected by the different additives. In conclusion, the ETEC challenge model induced distinct clinical signs of PWD in piglets, but the tested feed additives had no preventive effect under these conditions.

Presence of non-O157 Shiga toxin-producing Escherichia coli, enterotoxigenic E. coli, enteropathogenic E. coli and Salmonella in fresh beetroot (Beta vulgaris L.) juice from public markets in Mexico.

BACKGROUND: Unpasteurized juice has been associated with foodborne illness outbreaks for many years. Beetroot is a vegetable grown all over the world in temperate areas. In Mexico beetroot is consumed cooked in salads or raw as fresh unpasteurized juices. No data about the microbiological quality or safety of unpasteurized beetroot juices are available. Indicator bacteria, diarrheagenic Escherichia coli pathotypes (DEP) and Salmonella frequencies were determined for fresh unpasteurized beetroot juice from restaurants. RESULTS: One hundred unpasteurized beetroot juice samples were collected from public markets in Pachuca, Mexico. Frequencies in these samples were 100%, 75%, 53%, 9% and 4% of positive samples, for coliform bacteria, fecal coliforms, E. coli, DEP and Salmonella, respectively. Identified DEP included enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC) and non-O157 Shiga toxin-producing E. coli (STEC). Identified Salmonella serotypes included Typhimurium and Enteritidis. CONCLUSION: This is the first report of microbiological quality and atypical EPEC, ETEC, non-O157 STEC and Salmonella isolation from fresh raw beetroot juice in Mexico. Fresh raw beetroot juice from markets is very probably an important factor contributing to the endemicity of atypical EPEC, ETEC, non-O157 STEC and Salmonella-related gastroenteritis in Mexico.