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Poultry Science Mar 2014Salmonella spp. are widespread foodborne pathogens that contaminate egg and poultry meats. Attachment, colonization, as well as biofilm formation capacity of Salmonella...
Salmonella spp. are widespread foodborne pathogens that contaminate egg and poultry meats. Attachment, colonization, as well as biofilm formation capacity of Salmonella spp. on food and contact surfaces of food may cause continuous contamination. Biofilm may play a crucial role in the survival of salmonellae under unfavorable environmental conditions, such as in animal slaughterhouses and processing plants. This could serve as a reservoir compromising food safety and human health. Addition of antimicrobial preservatives extends shelf lives of food products, but even when products are supplemented with adequate amounts of preservatives, it is not always possible to inhibit the microorganisms in a biofilm community. In this study, our aims were i) to determine the minimum inhibitory concentrations (MIC) and minimum biofilm inhibitory concentrations (MBIC) of selected preservatives against planktonic and biofilm forms of Salmonella spp. isolated from chicken samples and Salmonella Typhimurium SL1344 standard strain, ii) to show the differences in the susceptibility patterns of same strains versus the planktonic and biofilm forms to the same preservative agent, and iii) to determine and compare antimicrobial and antibiofilm effects of selected food preservatives against Salmonella spp. For this purpose, Salmonella Typhimurium SL1344 standard strain and 4 Salmonella spp. strains isolated from chicken samples were used. Investigation of antimicrobial and antibiofilm effects of selected food preservatives against Salmonella spp. was done according to Clinical and Laboratory Standards Institute M100-S18 guidelines and BioTimer assay, respectively. As preservative agents, pure ciprofloxacin, sodium nitrite, potassium sorbate, sodium benzoate, methyl paraben, and propyl paraben were selected. As a result, it was determined that MBIC values are greater than the MIC values of the preservatives. This result verified the resistance seen in a biofilm community to food preservatives and highlighted this subject, not to be ignored in food applications.
Topics: Animals; Anti-Bacterial Agents; Biofilms; Chickens; Food Preservatives; Meat; Microbial Sensitivity Tests; Salmonella; Salmonella typhimurium
PubMed: 24604864
DOI: 10.3382/ps.2013-03404 -
Epidemiology and Infection Dec 2004Street-vendors in Mexico City provide ready-to-eat food to a high proportion of the inhabitants. Nevertheless, their microbiological status, general hygienic and trading...
Street-vendors in Mexico City provide ready-to-eat food to a high proportion of the inhabitants. Nevertheless, their microbiological status, general hygienic and trading practices are not well known. During spring and summer 2000, five tianguis (open markets) were visited and 48 vendors in 48 stalls interviewed. A total of 103 taco dressings were sampled for E. coli and Salmonella spp.: 44 (43%) contained E. coli and 5 (5%) Salmonella (2 S. Enteritidis phage type 8, 1 S. Agona, 2 S. B group). Both E. coli and salmonellas were isolated from three samples. Of Salmonella-positive stalls 80% (4/5) had three or more food-vendors and 80% of vendors were males, compared with 37.3% (16/43) and 46.4% (20/43) in the Salmonella-negative stalls respectively. Food-vendors kept water in buckets (reusing it all day), lacked toilet facilities, and prepared taco dressings the day before which remained at the tianguis without protection for 7.8 h on average. Consumption of street-vended food by local and tourist populations poses a health risk.
Topics: Cities; Commerce; Data Collection; Escherichia coli; Escherichia coli Infections; Food Contamination; Humans; Hygiene; Mexico; Prevalence; Public Health; Risk Assessment; Salmonella; Salmonella Infections; Seasons
PubMed: 15635978
DOI: 10.1017/s0950268804003036 -
Journal of Food Protection Dec 2002A 1-year study was carried out to investigate the prevalence of Salmonella in two abattoir environments coded "A" and "B" in Gaborone, Botswana. The total number of...
A 1-year study was carried out to investigate the prevalence of Salmonella in two abattoir environments coded "A" and "B" in Gaborone, Botswana. The total number of environmental samples collected from abattoirs A and B was 250 and 300, respectively. The samples were taken from soils in the corrals, knife blades, saw blades, cattle-drinking water, cattle feces, and feed. Preenrichment, enrichment, and selective/differential media, which enabled the favorable growth of Salmonella, were used in the study. Salmonellae were present in all sampled environments. The most common serotypes found in the environment at abattoir A were E1, C1, C2, and B. Serotypes B, C1, C2, C3, and E1 were common in abattoir B. Antigenic characterization of the salmonellae isolates showed that Salmonella Anatum, Salmonella Azteca, Salmonella Saintpaul, Salmonella Cerro, and Salmonella Westhampton were predominant in abattoir A, whereas Salmonella Anatum, Salmonella Mbandaka, Salmonella Molade, Salmonella Reading, and Salmonella Oranienburg were dominant in abattoir B. Implementing hazard analysis critical control point principles in work procedures would definitely reduce the gross contamination taking place in abattoirs.
Topics: Abattoirs; Animals; Botswana; Cattle; Cross Infection; Equipment Contamination; Feces; Food Microbiology; Prevalence; Salmonella; Serotyping; Soil Microbiology; Water Microbiology
PubMed: 12495003
DOI: 10.4315/0362-028x-65.12.1869 -
Proceedings of the National Academy of... Aug 2021spp. express pathogenicity island 1 Type III Secretion System 1 (T3SS-1) genes to mediate the initial phase of interaction with their host. Prior studies indicate...
spp. express pathogenicity island 1 Type III Secretion System 1 (T3SS-1) genes to mediate the initial phase of interaction with their host. Prior studies indicate short-chain fatty acids, microbial metabolites at high concentrations in the gastrointestinal tract, limit population-level T3SS-1 gene expression. However, only a subset of cells in a population express these genes, suggesting short-chain fatty acids could decrease T3SS-1 population-level expression by acting on per-cell expression or the proportion of expressing cells. Here, we combine single-cell, theoretical, and molecular approaches to address the effect of short-chain fatty acids on T3SS-1 expression. Our in vitro results show short-chain fatty acids do not repress T3SS-1 expression by individual cells. Rather, these compounds act to selectively slow the growth of T3SS-1-expressing cells, ultimately decreasing their frequency in the population. Further experiments indicate slowed growth arises from short-chain fatty acid-mediated depletion of the proton motive force. By influencing the T3SS-1 cell-type proportions, our findings imply gut microbial metabolites act on cooperation between the two cell types and ultimately influence 's capacity to establish within a host.
Topics: Bacterial Proteins; Bacteriological Techniques; Culture Media; Fatty Acids, Volatile; Gene Expression Regulation, Bacterial; Microfluidics; Salmonella
PubMed: 34330831
DOI: 10.1073/pnas.2103027118 -
The Journal of Hygiene Feb 1982One hundred and eighty-two raw, 112 pre-cooked and 750 cooked hamburgers composed mainly of beef or beef and pork were subjected to microbiological examination.Raw...
One hundred and eighty-two raw, 112 pre-cooked and 750 cooked hamburgers composed mainly of beef or beef and pork were subjected to microbiological examination.Raw hamburgers gave total bacterial counts from 10(6) to 10(8) per g, counts of Enterobacteriaceae from 10(4) to 10(6) per g, of Escherichia coli from 10(3) to 10(5), of group D streptococci from 10(2) to 10(4), of Staphylococcus aureus from 3 to 10(2) and of Clostridium perfringens less than 10 bacteria per g. Of the samples, 32% contained salmonellas; the highest most probable number was 10(2) per g but most estimates were below 1 per g. Corresponding figures for the pre-cooked samples were 2-3 log cycles lower, and only one sample contained salmonella. Yersinia enterocolitica was not isolated from any raw or pre-cooked sample.Three hundred and ninety-five of the cooked hamburgers were prepared by grilling raw hamburgers for between 2 and 5.5 min. These gave total bacterial counts from 10(5) to 10(7) per g, and counts of Enterobacteriaceae from 10(2) to 10(5) per g. Of the samples, 9.4% contained salmonellas, always in numbers below 1 per g. The remaining 355 cooked hamburgers were prepared from samples pre-cooked for 10 min at 80 degrees C. Some were grilled and some fat fried. The total bacterial counts were from 10(3) to 10(5) per g, and counts of Enterobacteriaceae below 10(2) per g. Salmonellae, again in small numbers only, were recovered from 3.5% of samples.When hamburgers were artificially contaminated with Salmonella typhimurium it took 5.5 min on a commercial grill, 2.25 min frying in a frying pan and 1.75 min on a household grill to reliably reduce the salmonella count one hundredfold. This means that at many vending places hamburgers are often cooked for too short a time.D-values were determined for S. typhimurium in hamburger meat at 50, 55, 60, 65 and 70 degrees C, these values were 7.1, 5.1, 1.2, 0.9 and 0.6 min respectively. It can be concluded that the heating action in the centre of the hamburgers will take place more slowly than in the hamburger as a whole, and that the time between cooking and consumption is very important in reducing the microbial load to acceptable levels.Pre-cooking (10 min at 80 degrees C in a water bath) gives a reduction in the numbers of salmonella of about 4 x 10(3), after which cooking gives a further reduction as mentioned above.
Topics: Animals; Cattle; Clostridium perfringens; Cooking; Enterobacteriaceae; Escherichia coli; Food Contamination; Food Handling; Food Microbiology; Horses; Hot Temperature; Meat; Salmonella; Staphylococcus aureus; Streptococcus; Swine; Yersinia
PubMed: 6276464
DOI: 10.1017/s0022172400069989 -
PloS One 2018The transmission of Salmonella enterica within a vertically integrated poultry operation was investigated longitudinally over an 18-month period (2013-2014). Thirty six...
Salmonella spp. transmission in a vertically integrated poultry operation: Clustering and diversity analysis using phenotyping (serotyping, phage typing) and genotyping (MLVA).
The transmission of Salmonella enterica within a vertically integrated poultry operation was investigated longitudinally over an 18-month period (2013-2014). Thirty six percent of all samples collected (1503 of 4219) were positive for salmonellae with seven Salmonella enterica subsp. enterica serovars, and one Salmonella enterica subsp. salamae serovar detected. Both Salmonella enterica subsp. enterica serovars Infantis and Typhimurium were detected in all locations sampled. Salmonella Typhimurium was the most frequently detected serovar (63% of serotyped samples) with 8 phage types (PT) and 41 multiple-locus variable-number tandem-repeats analysis (MLVA) profiles identified. The most frequently identified phage types were PT135a and DT135. A total of 62 PT/MLVA combinations were observed. MLVA profiles 03-14-10-09-525 and 03-15-11-11-525 were the most frequently identified and 83% of the isolates shared at least one MLVA profile with an isolate from another phage type. The use of phage typing and MLVA profiling, on their own or in combination, were insufficient to understand the complexity of the epidemiological relationships between locations within this production system. Despite the high level of apparent diversity, cluster analysis was unable to differentiate the transmission pathways of all S. Typhimurium variants detected within the integrated enterprise. Using additional epidemiological information, the parent breeder rearing site was identified as the most likely point of introduction of two S. Typhimurium isolates into the production system with subsequent dissemination to the broiler flocks via the hatchery. This complexity is unable to be resolved in the absence of intensive sampling programs at all generations of the production system.
Topics: Animals; Bacteriophage Typing; Chickens; Genotype; Minisatellite Repeats; Molecular Typing; Phenotype; Poultry; Salmonella; Salmonella Infections; Serotyping
PubMed: 30024964
DOI: 10.1371/journal.pone.0201031 -
Journal of Infection in Developing... Jun 2012Resistance of Salmonella to therapeutic agents currently being used for treatment of Salmonella infections is emerging as a global problem. This study aimed to assess...
INTRODUCTION
Resistance of Salmonella to therapeutic agents currently being used for treatment of Salmonella infections is emerging as a global problem. This study aimed to assess the prevalence of Salmonella serotypes and their susceptibility patterns to commonly used drugs for treatment of Salmonella infections including quinolones. Correlation between nalidixic acid susceptibility of these isolates and their ciprofloxacin minimum inhibitory concentrations was also sought.
METHODOLOGY
Salmonella isolates (n=213) were collected between January 2007 and May 2009 at King Khalid University Hospital in Riyadh, Saudi Arabia. The isolates were serotyped and their susceptibilities to commonly used first-line anti-Salmonella drugs (ampicillin, ceftriaxone, trimethoprim/sulfamethoxazole, nalidixic acid and ciprofloxacin) were determined using the automated Microscan system, the Kirby-Bauer disk diffusion method, and E-test.
RESULTS
The most frequently detected serotype was D1 (37%) followed by the serotypes, B (24%) and C1 (11%). Non-typable Salmonella isolates detected using available conventional Salmonella anti-sera were (11%). Overall resistance rates to nalidixic acid, ampicillin, trimethoprim/sulfamethoxazole and ceftriaxone were 99/213 (46%), 43/213 (20%), 34/213 (16%) and 7/213 (3%), respectively. Of the total isolates, 117 (55%) had a ciprofloxacin MIC of <0.125 µg/ml and among these 105 (90%) were susceptible to nalidixic acid. The remaining 96 (45%) isolates had a ciprofloxacin MIC of ≥ 0.125 µg/ml and among them, 83 (86.5%) were resistant to nalidixic acid.
CONCLUSIONS
The majority of Salmonella isolates in this study were non-typhi serotypes. Significantly higher proportions of Salmonellae were resistant to nalidixic acid and ciprofloxacin and a vast majority of nalidixic acid resistant organisms exhibited decreased susceptibility to ciprofloxacin.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents; Child; Child, Preschool; Drug Resistance, Bacterial; Female; Hospitals; Humans; Infant; Male; Microbial Sensitivity Tests; Middle Aged; Prevalence; Prospective Studies; Salmonella; Salmonella Infections; Saudi Arabia; Serotyping; Young Adult
PubMed: 22706189
DOI: 10.3855/jidc.1805 -
Applied and Environmental Microbiology Sep 2006Genes of Salmonella enterica serovar Typhimurium LT2 expected to be specifically present in Salmonella were selected using the Basic Local Alignment Search Tool (BLAST)... (Comparative Study)
Comparative Study
Genes of Salmonella enterica serovar Typhimurium LT2 expected to be specifically present in Salmonella were selected using the Basic Local Alignment Search Tool (BLAST) program. The 152 selected genes were compared with 11 genomic sequences of Salmonella serovars, including Salmonella enterica subsp. I and IIIb and Salmonella bongori (V), and were clustered into 17 groups by their comparison patterns. A total of 38 primer pairs were constructed to represent each of the 17 groups, and PCR was performed with various Salmonella subspecies including Salmonella enterica subsp. I, II, IIIa, IIIb, IV, VI, and V to evaluate a comprehensive DNA-based scheme for identification of Salmonella subspecies and the major disease-causing Salmonella serovars. Analysis of PCR results showed that Salmonella enterica subsp. I was critically divided from other subspecies, and Salmonella strains belonging to S. enterica subsp. I were clustered based on their serovars. In addition, genotypic relationships within S. enterica subsp. I by PCR results were investigated. Also, Salmonella signature genes, Salmonella enterica serovar Typhimurium signature genes, and Salmonella enterica subsp. I signature genes were demonstrated based on their PCR results. The described PCR method suggests a rapid and convenient method for identification of Salmonella serovars that can be used by nonspecialized laboratories. Genome sequence comparison can be a useful tool in epidemiologic and taxonomic studies of Salmonella.
Topics: Bacterial Typing Techniques; Base Sequence; DNA Primers; DNA, Bacterial; Genome, Bacterial; Genotype; Phylogeny; Polymerase Chain Reaction; Salmonella enterica; Salmonella typhimurium; Sequence Homology, Nucleic Acid; Serotyping; Species Specificity
PubMed: 16957240
DOI: 10.1128/AEM.00138-06 -
Genetics Jul 1998The spv operon is common to all Salmonella virulence plasmids. DNA hybridization analysis indicates that the spv region is limited in distribution to serovars of...
Salmonella virulence plasmid. Modular acquisition of the spv virulence region by an F-plasmid in Salmonella enterica subspecies I and insertion into the chromosome of subspecies II, IIIa, IV and VII isolates.
The spv operon is common to all Salmonella virulence plasmids. DNA hybridization analysis indicates that the spv region is limited in distribution to serovars of Salmonella enterica subspecies I, II, IIIa, IV, and VII and is absent from Salmonella bongori isolates. Among strains of subspecies II, IIIa, and VII, all isolates examined contained sequences that hybridized with the spv region. However, among isolates of subspecies I, DNA sequences capable of hybridizing with the spv region were found in some isolates of certain serovars. Furthermore, in isolates of subspecies I, the virulence plasmid was found in the same set of isolates as an F-related plasmid, as determined by the presence of the spv region of the virulence plasmid and the finO, traD, and repA sequences of the F-plasmid. The concordance of the virulence plasmid and all three F-plasmid sequences in subspecies I serovar Choleraesuis, Paratyphi, and Typhimurium is most easily explained if the spv region is carried in an F-related plasmid in these isolates. In contrast, among S. enterica subspecies II, IIIa, IV, and VII, the isolates that contain spv sequences did not hybridize with an F-related plasmid or any other identifiable plasmid. With the use of pulse-field gel electrophoresis, the spv region in subspecies II, IIIa, and VII was found to be encoded on the chromosome. Analysis of the phylogenetic distribution of spv among Salmonella isolates and comparative nucleotide sequence analysis of spvA and spvC suggests that the spv region was acquired very recently, after speciation of the salmonellae.
Topics: Base Sequence; Chromosomes, Bacterial; F Factor; Mutagenesis, Insertional; Operon; Phylogeny; Polymerase Chain Reaction; Polymorphism, Genetic; Salmonella enterica; Salmonella enteritidis; Salmonella paratyphi A; Salmonella typhimurium; Sequence Alignment; Sequence Deletion; Sequence Homology, Nucleic Acid; Virulence
PubMed: 9649513
DOI: 10.1093/genetics/149.3.1183 -
Applied and Environmental Microbiology Jun 2004The ability of salmonellae to become internalized and to survive and replicate in amoebae was evaluated by using three separate serovars of Salmonella enterica and five...
The ability of salmonellae to become internalized and to survive and replicate in amoebae was evaluated by using three separate serovars of Salmonella enterica and five different isolates of axenic Acanthamoeba spp. In gentamicin protection assays, Salmonella enterica serovar Dublin was internalized more efficiently than Salmonella enterica serovar Enteritidis or Salmonella enterica serovar Typhimurium in all of the amoeba isolates tested. The bacteria appeared to be most efficiently internalized by Acanthamoeba rhysodes. Variations in bacterial growth conditions affected internalization efficiency, but this effect was not altered by inactivation of hilA, a key regulator in the expression of the invasion-associated Salmonella pathogenicity island 1. Microscopy of infected A. rhysodes revealed that S. enterica resided within vacuoles. Prolonged incubation resulted in a loss of intracellular bacteria associated with morphological changes and loss of amoebae. In part, these alterations were associated with hilA and the Salmonella virulence plasmid. The data show that Acanthamoeba spp. can differentiate between different serovars of salmonellae and that internalization is associated with cytotoxic effects mediated by defined Salmonella virulence loci.
Topics: Acanthamoeba; Animals; Bacterial Proteins; Cell Line; Colony Count, Microbial; Culture Media; Dogs; Humans; Microscopy, Electron; Salmonella enterica; Trans-Activators; Virulence
PubMed: 15184177
DOI: 10.1128/AEM.70.6.3706-3714.2004