Frequency of indicator bacteria,Salmonella and diarrhoeagenic Escherichia coli pathotypes on ready‐to‐eat cooked vegetable salads from Mexican restaurants

The presence of coliform bacteria, faecal coliforms, Escherichia coli, diarrhoeagenic E. coli pathotypes (DEP) and Salmonella were determined in ready‐to‐eat cooked vegetable salads (RECS) from restaurants in Pachuca city, Mexico. The RECS were purchased from three types of restaurants: national chain restaurants (A), local restaurants (B) and small restaurants (C). Two restaurants for each A and B, and three for C, were included. Forty RECS samples were purchased at each A and B restaurant and 20 at each C restaurant. Of the overall total of 220 analysed samples, 100, 98·2, 72·3, 4·1 and 4·1% had coliform bacteria, faecal coliforms, E. coli, DEP and Salmonella, respectively. Identified DEP included enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC) and Shiga toxin‐producing E. coli (STEC). The EPEC, ETEC and STEC were isolated each from 1·4% of samples. No E. coli O157:H7 were detected in any STEC‐positive samples. The analysis of Kruskal–Wallis anova and median test of microbiological data showed that the microbiological quality of RECS did not differ between the different restaurants (P > 0·05).

Significance and Impact of the Study

This is the first report regarding microbiological quality and Salmonella, enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC) and Shiga toxin‐producing E. coli (STEC) isolation from ready‐to‐eat cooked vegetable salads from Mexican restaurants. Ready‐to‐eat cooked vegetable salads could be an important factor contributing to the endemicity of EPEC, ETEC and STEC, and Salmonella caused gastroenteritis in Mexico.     

猪源大肠杆菌(ETEC、STEC、AEEC)毒力基因及其与O抗原型的关系

[目的]揭示从我国部分地区仔猪腹泻或水肿病病猪体内分离到的300个大肠杆菌分离株所属病原型(pathotype)、毒力基因及其与O血清型的关系.[方法]O血清型采用常规的凝集试验进行测定,毒力基因采用PCR方法检测.[结果]通过对这300个分离株的O血清型及其毒素、紧密素和黏附素基因进行鉴定,结果显示除50株未定型、17株自凝外,测定出233个分离株的血清型,这些分离株覆盖了45个血清型,其中以0149、0107、0139、093和091为主,共133株,占定型菌株的57.1%;拥有est Ⅰ、estⅡ、elt、stx2e和eae A基因的菌株分别为102(34.0%)、190(63.3%)、81(27.0%)、57(19.0%)和54(18.0%)株;分离株中有51株K88基因阳性(其中菌毛表达率为100%),75株F18基因阳性(其中菌毛表达率为50.7%),在K88菌株中,0149血清型与est Ⅰ或estⅡ elt密切相关,在F18菌株中,0107血清型与est Ⅰ或estⅡ、0139血清型与stx2e紧密相关.依其毒力特征可将这些分离株分为以下6种类型:ETEC、STEC、AEEC、ETEC/STEC、AEEC/ETEC和AEEC/ETEC/STEC,分别拥有190、24、36、32、17和1个菌株,占分离株的63.3%、8.0%、12.0%、10.7%、5.7%和0.3%.通过分析这些分离株的O血清型、毒素类型和黏附素型之间的相关性:猪源ETEC以0149、0107、093和098等血清型为主,0149:K88菌株主要与estⅡ或estⅡ elt肠毒素相关,0107:F18菌株主要与estⅡ相关,093和098血清型菌株主要与estⅡ肠毒素相关;STEC菌株以0139:F18血清型为主,拥有stx2e;AEEC菌株拥有紧密素,无明显优势血清型;ETEC/STEC菌株以0107:F18和0116:F18血清型为主,主要与est Ⅰ stx2e或estⅡ stx2e密切相关,ETEC/AEEC菌株以091和0107血清型为主,全部拥有肠毒素est Ⅰ和紧密素基因.[结论]我国至少存在6种病原型的猪肠道致病性大肠杆菌,其中ETEC为我国部分地区猪大肠杆菌病的主要病原,同时其病原型日益复杂.     

Escherichia coli biofilm: development and therapeutic strategies

Escherichia coli biofilm consists of a bacterial colony embedded in a matrix of extracellular polymeric substances (EPS) which protects the microbes from adverse environmental conditions and results in infection. Besides being the major causative agent for recurrent urinary tract infections, E. coli biofilm is also responsible for indwelling medical device‐related infectivity. The cell‐to‐cell communication within the biofilm occurs due to quorum sensors that can modulate the key biochemical players enabling the bacteria to proliferate and intensify the resultant infections. The diversity in structural components of biofilm gets compounded due to the development of antibiotic resistance, hampering its eradication. Conventionally used antimicrobial agents have a restricted range of cellular targets and limited efficacy on biofilms. This emphasizes the need to explore the alternate therapeuticals like anti‐adhesion compounds, phytochemicals, nanomaterials for effective drug delivery to restrict the growth of biofilm. The current review focuses on various aspects of E. coli biofilm development and the possible therapeutic approaches for prevention and treatment of biofilm‐related infections.     

Antimicrobial resistance in faecal enterococci and Escherichia coli isolates recovered from Iberian wolf

The aim of this study was to report the antimicrobial resistance, the molecular mechanisms associated and the detection of virulence determinants within faecal Enterococcus spp. and Escherichia coli isolates of Iberian wolf. Enterococci (n = 227) and E. coli (n = 195) isolates were obtained from faecal samples of Iberian wolf (Canis lupus signatus). High rates of resistance were detected for tetracycline and erythromycin among the enterococci isolates, and most of resistant isolates harboured the tet(M) and/or tet(L) and erm(B) genes, respectively. The bla_TEM, tet(A) and/or tet(B), and aadA or strA‐strB genes were detected among most ampicillin‐, tetracycline‐ or streptomycin‐resistant E. coli isolates, respectively. E. coli isolates were ascribed to phylogroups A (n = 56), B1 (91), B2 (13) and D (35). The occurrence of resistant enterococci and E. coli isolates in the faecal flora of Iberian wolf, including the presence of resistant genes in integrons, and virulence determinants was showed in this study. Iberian wolf might act as reservoir of certain resistance genes that could be spread throughout the environment.

Significance and Impact of the Study

This study shows antimicrobial resistance in commensal bacteria from the free‐range, Portuguese, Iberian wolf population. The results indicate that the Iberian wolf could contribute to the spread of resistant bacteria throughout the environment. Additionally, in case of infection, an increased risk of therapeutic failure due to the presence of multiresistant bacteria may represent a health problem for this endangered species. Future studies must be performed to analyse the possible contamination of these animals through the environment and/or the food chain.