ABSTRACT
192 Food samples (commonly consumed 8 food types), 355 animal samples (animal feces of bovine, ovine, goat and chicken) and 50 samples from clinical human cases in Sanliurfa city, Turkey in a year were collected to determine the Salmonella enterica subsp. enterica mosaic in Turkey. 161 Salmonella isolates represented 17 serotypes, 20 sequence types (STs) and 44 PFGE patterns (PTs). 3 serotypes, S. Enteritidis, S. Typhimurium and S. Kentucky, were recovered from three different hosts. The highest discriminatory power was obtained by PFGE (SID=0.945), followed by MLST (SID=0.902) and serotyping (SID=0.885) for all isolates. The prevalence of antimicrobial resistance genes (aadA1, aadA2, strA, strB, aphA1-Iab, blaTEM-1, blaPSE-1, tetA) was highly correlated with phenotypic profiles of aminoglycoside, ß-lactam and tetracycline groups (kappa >0.85). From our knowledge, this is the first study reporting spatial and temporal distribution of Salmonella species through phenotypic and genetic approaches over farm to fork chain in Turkey. Thus, our data provided further information for evolution, ecology and transmission of Salmonella in Turkey.
Subject(s)
Anti-Bacterial Agents/pharmacology , Chickens/microbiology , Drug Resistance, Multiple, Bacterial/genetics , Goats/microbiology , Meat/microbiology , Salmonella Infections, Animal/microbiology , Salmonella enterica , Sheep/microbiology , Animals , Cattle , Electrophoresis, Gel, Pulsed-Field , Foodborne Diseases/microbiology , Geography , Humans , Microbial Sensitivity Tests , Multilocus Sequence Typing , Salmonella enterica/classification , Salmonella enterica/drug effects , Salmonella enterica/genetics , Salmonella enterica/isolation & purification , Serotyping , Tetracycline Resistance/genetics , Turkey , beta-Lactam Resistance/geneticsABSTRACT
Four lactococcal bacteriophages (phiLl6-2, phiLl35-6, phiLd66-36 and phiLd67-42) in M17 broth were pressurized at 300 and 350 MPa at room temperature and their survival curves were determined at various time intervals. Tailing (monotonic upward concavity) was observed in all survival curves. The resulting non-linear semi-logarithmic survival curves were described by the Weibull model and goodness of fit of this model was investigated. Regression coefficients (R2), root mean square error (RMSE), residual and correlation plots strongly suggested that Weibull model produced a better fit to the data than the traditional linear model. Hazard plots suggested that the Weibull model was fully appropriate for the data being analyzed. These results have confirmed that the Weibull model, which is mostly utilized to describe the inactivation of bacterial cells or spores by heat and pressure, could be successfully used in describing the lactococcal bacteriophage inactivation by high hydrostatic pressure.
Subject(s)
Bacteriophages/growth & development , Food Microbiology , Hydrostatic Pressure , Lactococcus/virology , Models, Biological , Kinetics , Mathematics , Models, StatisticalABSTRACT
The aim of the current study was to develop, a new, rapid, sensitive and quantitative Salmonella detection method using a Real-Time PCR technique based on an inexpensive, easy to produce, convenient and standardized recombinant plasmid positive control. To achieve this, two recombinant plasmids were constructed as reference molecules by cloning the two most commonly used Salmonella-specific target gene regions, invA and ttrRSBC. The more rapid detection enabled by the developed method (21 h) compared to the traditional culture method (90 h) allows the quantitative evaluation of Salmonella (quantification limits of 10(1)CFU/ml and 10(0)CFU/ml for the invA target and the ttrRSBC target, respectively), as illustrated using milk samples. Three advantages illustrated by the current study demonstrate the potential of the newly developed method to be used in routine analyses in the medical, veterinary, food and water/environmental sectors: I--The method provides fast analyses including the simultaneous detection and determination of correct pathogen counts; II--The method is applicable to challenging samples, such as milk; III--The method's positive controls (recombinant plasmids) are reproducible in large quantities without the need to construct new calibration curves.
Subject(s)
DNA, Recombinant/genetics , Milk/microbiology , Plasmids/genetics , Real-Time Polymerase Chain Reaction/methods , Salmonella enterica/genetics , Salmonella enterica/isolation & purification , Animals , Bacterial Proteins/genetics , Bacterial Proteins/isolation & purification , Bacteriological Techniques , Cloning, Organism , DNA Primers , DNA Probes , DNA, Bacterial/genetics , Environmental Microbiology , Food Microbiology , Milk/chemistry , Salmonella Infections/diagnosis , Salmonella Infections/microbiology , Salmonella enterica/classification , Salmonella typhimurium/genetics , Salmonella typhimurium/isolation & purification , Serotyping/methods , Water MicrobiologyABSTRACT
The plasmid stability of three wild type Lactococcus lactis strains and their mutants was investigated at different incubation time and temperatures in two different media [M17 broth and reconstituted skim milk (RSM)]. The results showed that both incubation times and temperature are effective on plasmid loss. The plasmid profiles of wild type strains exhibited 8 to 9 distinct plasmid species with molecular weights from 2.1 to 24.0 kb. Lactose fermentation ability was found to be encoded by 22.2 (strain U70), 23.6 (strain U29) and 24.0 (strain U52) kb plasmids in the wild type strains, respectively. The stabilities of the plasmids were explained by applying a second-order polynomial modeling system. Reasonable fittings were obtained for the model and the adjusted regression coefficients (R ( 2 ) (adj)) were between 0.76 and 0.99 for the overall data. Overall, it was found that incubation time had the most profound effect on plasmid stability, with plasmid loss occurring after 72 h, while temperatures in the range of 15-40 degrees C also induced plasmid instability.