The aim of this study was to detect the expression of 4 clinically-important efflux pumps in the Resistance-Nodulation-Cell Division (RND) family including MexAB-OprM, MexXY, MexCD-OprJ and MexEF-OprN in Pseudomonas a...The aim of this study was to detect the expression of 4 clinically-important efflux pumps in the Resistance-Nodulation-Cell Division (RND) family including MexAB-OprM, MexXY, MexCD-OprJ and MexEF-OprN in Pseudomonas aeruginosa using a combination of resistance-phenotypic markers and multiplex RT-PCR (mRT-PCR). The antibiotic substrates specific for each Mex systems were used as phenotypic markers including carbenicillin, MexAB-OprM, erythromycin, MexCD-OprJ, norfloxacin and imipenem, MexEF-OprN and gentamicin, MexXY-OprM. The methods were validated with reference strains with known genotypes of the Mex systems and the potential applicability in clinical practice was tested with clinical isolates. The results for the reference strains support that the combination of resistance phenotype and mRT-PCR is a potential-attractive method for diagnosis of efflux-mediated resistance in P. aeruginosa. Further development to make it more practical for clinical use and study in a larger number of clinical isolates is required.展开更多
Produce-associated food-borne outbreaks have been increasingly implicated as the significant proportion of the annual incidence of food-borne ilness worldwide.The objectives of this study were to determine the concent...Produce-associated food-borne outbreaks have been increasingly implicated as the significant proportion of the annual incidence of food-borne ilness worldwide.The objectives of this study were to determine the concentrations of indicator bacteria and the presence of Salmonella spp.Shigella spp..Escherichia coli(E.coln 0157:H7,and Listeria monocytogenes(L.monocytogenes),and to characterize predictors associated with Salmonella contamination of retail produce from fresh markets and supermarkets in Bangkok,Thailand.A total of 503 samples were col-lected during May 2018 and February 2019,comprised of sweet basil,spring onion,coriander,cabbage,lettuce,cucumber,and tomato,with conventional items from fresh open-air markets(n=167),conventional items from supermarkets(n=168),and organic items from supermarkets(n=168).The overall prevalence in these 503 items for fecal coliforms and E.coli was 84.3%and 71.4%,with mean concentrations(±standard deviation)of fecal coliforms and E.coli being(3.0×10^(5)±1.3×10^(5))most probable number(MPN)/g and(1.8×10^(5)±1.1×10^(5))MPN/g,respectively.The concentrations of fecal coliforms and E.coli were higher in produce sampled from fresh open-air markets than produce from supermarkets;simi-larly,these bacterial indicators were higher from produce grown under conventional methods than certified organic produce.The prevalence of Salmonella and Shigella was 4.8%and 0.4%,respectively,but no positives were found for E.coli 0157:H7 and L.monocytogenes.The predom-inant Salmonella serovar was Stanley(30.8%).Based on logistic regression,the odds of Salmonella contamination were significantly(P<0.05)higher during the rainy versus dry season,produce grown using conventional versus organic agriculture,sweet basil versus other commodities,and using ice tank versus dry refrigeration for overnight retail storage.This study indicated that fruits and vegetables are important sources of microbial contamination.Hence,monitoring and surveillance of pathogen contamination to produce is needed to strengthen food safety.展开更多
文摘The aim of this study was to detect the expression of 4 clinically-important efflux pumps in the Resistance-Nodulation-Cell Division (RND) family including MexAB-OprM, MexXY, MexCD-OprJ and MexEF-OprN in Pseudomonas aeruginosa using a combination of resistance-phenotypic markers and multiplex RT-PCR (mRT-PCR). The antibiotic substrates specific for each Mex systems were used as phenotypic markers including carbenicillin, MexAB-OprM, erythromycin, MexCD-OprJ, norfloxacin and imipenem, MexEF-OprN and gentamicin, MexXY-OprM. The methods were validated with reference strains with known genotypes of the Mex systems and the potential applicability in clinical practice was tested with clinical isolates. The results for the reference strains support that the combination of resistance phenotype and mRT-PCR is a potential-attractive method for diagnosis of efflux-mediated resistance in P. aeruginosa. Further development to make it more practical for clinical use and study in a larger number of clinical isolates is required.
基金the University of California Davis(A18-1020-S001),USAthe Chulalongkorn University Graduate Scholarship to Commemorate the 72nd Anniversary of His Majesty King Bhumibol Adulyadej(Thailand)to Jutanat Srisamran.
文摘Produce-associated food-borne outbreaks have been increasingly implicated as the significant proportion of the annual incidence of food-borne ilness worldwide.The objectives of this study were to determine the concentrations of indicator bacteria and the presence of Salmonella spp.Shigella spp..Escherichia coli(E.coln 0157:H7,and Listeria monocytogenes(L.monocytogenes),and to characterize predictors associated with Salmonella contamination of retail produce from fresh markets and supermarkets in Bangkok,Thailand.A total of 503 samples were col-lected during May 2018 and February 2019,comprised of sweet basil,spring onion,coriander,cabbage,lettuce,cucumber,and tomato,with conventional items from fresh open-air markets(n=167),conventional items from supermarkets(n=168),and organic items from supermarkets(n=168).The overall prevalence in these 503 items for fecal coliforms and E.coli was 84.3%and 71.4%,with mean concentrations(±standard deviation)of fecal coliforms and E.coli being(3.0×10^(5)±1.3×10^(5))most probable number(MPN)/g and(1.8×10^(5)±1.1×10^(5))MPN/g,respectively.The concentrations of fecal coliforms and E.coli were higher in produce sampled from fresh open-air markets than produce from supermarkets;simi-larly,these bacterial indicators were higher from produce grown under conventional methods than certified organic produce.The prevalence of Salmonella and Shigella was 4.8%and 0.4%,respectively,but no positives were found for E.coli 0157:H7 and L.monocytogenes.The predom-inant Salmonella serovar was Stanley(30.8%).Based on logistic regression,the odds of Salmonella contamination were significantly(P<0.05)higher during the rainy versus dry season,produce grown using conventional versus organic agriculture,sweet basil versus other commodities,and using ice tank versus dry refrigeration for overnight retail storage.This study indicated that fruits and vegetables are important sources of microbial contamination.Hence,monitoring and surveillance of pathogen contamination to produce is needed to strengthen food safety.
