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There is a lack of information about Salmonella enterica strains under acidic conditions and their association with their genome. This study characterized intraspecies variability in the growth of 167 S. enterica isolates under two acid conditions (pH 4 and 5) and linked to the whole genome sequencing (WGS) data. A total of 1002 curves for each condition were obtained using turbidimetry measurements, and Baranyi and Roberts model was used to estimate the maximum rate of change (rcmax; OD600 nm h−1). Strains were categorized into slow, intermediate, and fast; and associations with their WGS data were performed. Huge variability in rcmax¯$\overline {{\mathrm{r}}{{{\mathrm{c}}}_{{\mathrm{max}}}}} $ was observed at both conditions (pH 5 = 0.016–0.066 OD600nm h−1 and pH 4 = 0.003–0.028 OD600nm h−1). The majority of isolates was classified as intermediate rcmax¯$\overline {{\mathrm{r}}{{{\mathrm{c}}}_{{\mathrm{max}}}}} $ (59.5% at pH 5 and 46.1% at pH 4). Strains classified as fast had a low frequency of allABCD genes at both pHs, and any of them having the presence of pefABCD, spvBCR, aadA2, dfrA12, and gyrA_D87G genes were linked to virulence or antimicrobial resistance. This study suggests that strains with fast capacity for growth under acidic conditions could have a fitness cost in their virulence or resistance potential. Practical Application: Data presented in this study could be used to select representative strains to evaluate the exposure assessment in different food items, mainly the growth and survival in acidic foods. [ABSTRACT FROM AUTHOR]

Escherichia coli is a widespread bacterium in the intestines of warm-blooded animals and is employed as an indicator of fecal pollution. A total of 238 E. coli isolates from human sources (HS) and nonhuman sources (NHS) were gathered from the Apalachicola National Estuarine Research Reserve, from associated sewage treatment plants and directly from animals and tested for ribotype profile. It was observed that discriminant analysis of ribotype profiles may be a useful technique for identifying HS and NHS fecal pollution.

To estimate human exposure to Salmonella enterica, it is essential to understand the pathogen distribution and characteristics. Prevalence and concentration of S. enterica were determined in mango, tomato, and raw chicken samples purchased in three states (Aguascalientes, Querétaro, and Guadalajara) located in the central region of Mexico during two seasons. In addition, S. enterica isolates were characterized by absence/presence of 13 virulence genes (chromosomal, prophage, and plasmid) and resistance to 14 antibiotics. A total of 300 samples of mango, 272 of tomato, and 354 of raw chicken were analyzed. The mean of the prevalence (24.9%) and concentration (−0.61 Log MPN/g) of S. enterica in chicken was higher than in mango (1.3%, −1.7 Log MPN/g) and tomato (1.1%, −1.7 Log MPN). Among S. enterica isolates (284), there were 7 different virulotypes, belonging 68.7% of isolates to V2; there was high variability in the presence of mobile genetic elements. The occurrence of specific mobile elements ranged from 81.4% to 11.3% among isolates. Among the isolates, 91.5% were resistant to at least one antibiotic with ampicillin being the most frequent; 54.9% of isolates were multidrug resistant. Data from this study can be used for quantitative microbial risk assessment of S. enterica related to mango, tomato, and raw chicken consumption in the central region of Mexico. Practical Application: Data on the prevalence and concentration of Salmonella enterica obtained in this study can be used to estimate the exposure assessment for the consumption of mango, tomato, and chicken in the central region of Mexico. In addition, the characteristics of the S. enterica isolates could be used to select representative strains for future studies to evaluate the intraspecies variability. [ABSTRACT FROM AUTHOR]

Vibrio vulnificus is an invasive organism found in oyster meat. It causes life-threatening diseases in humans even at low levels of concentration. This necessitates the use of enrichment broths to facilitate cultivation for diagnostic purposes. A study was launched to determine the components of the enrichment broth that could enhance the selective growth of the organism. V. vulnificus was found to grow better in a broth mixture of peptone, sodium chloride and cellubiose. Colistin methanesulfonate further increased growth while suppressing non-target bacteria.

The association of multiple-antibiotic-resistance profiles with point and nonpoint sources of Escherichia coli in Apalachicola Bay was investigated using E. coli antibiotic resistance to differentiate point sources (PS) and nonpoint sources (NPS) pollution within the area. Results indicate that antibiotic resistance profile of E. coli is associated with its source of pollution. Furthermore, the level of antibiotic resistance among PS and NPS isolates is similar to those from urban and rural waters.

Vibrio vulnificus is a pathogenic bacteria found in shellfish and estuarine waters and it causes a rapid, invasive and highly lethal disease. To predict the incidence of V. Vulnificus disease, it is necessary to determine the species genetic diversity. Pulsed-field gel electrophoresis, ribotype and biotype analyses reveal four dominant gene clusters among 53 clinical and 78 environmental strains. A a significant relationship between geography and genotype is also observed.

The cholera-causing bacterium Vibrio cholerae 01 will inhabit and remain in the oyster Crassostrea virginica at higher concentrations than Escherichia coli or Salmonella tallahassee following exposure to contaminated water and standard purification procedures. Licenced purification methods were not effective in removing the V. cholerae 01 from the oysters. The persistence of this bacteria was not directly related to the concentration of V. cholerae - 1-specific agglutinin in the oyster, as has been previously hypothesized.

Measurement of extracellular viability and intracellular viability of opaque and translucent colonial Vibrio vulnificus associated with phagocytic oyster hemocytes reveals that the levels of phagocytosis and bactericidal degradation of the opaque isolates are lower than those of the translucent morphotype. Encapsulation plays a role in the resistance to hemocytes-induced ingestion and degradation. V. cholerae and E. coli exhibit higher rates of intracellular death compared to the opaque V. vulnificus isolate. V. vulnificus-inoculated hemocyte monolayers exhibit similar levels of lysozyme activity and acid phosphatase activity.

Studies on the control of facultative pathogen Listeria monocytogenes in crabmeat reveal that lactic acid bacterium fermentation products and food-grade chemicals are good antilisterial agents to reduce the counts of L. monocytogenes in crabmeat. Washing of crabmeat with Perlac 1911 or nicin at levels between 10000 Au/ml and 20,000 Au/ml lowers L. monocytogenes count. Among food-grade chemicals, trisodium phosphate acts as a potent antimicrobial agent by elevating pH to deleterious levels affecting L. monocytogenes survival.

The relation of Vibrio vulnificus to phagocytic oyster hemocytes was investigated. Experiments were conducted with time, temperature, bacterial concentration, hemolymph pretreatment and V. vulnificus translucent and opaque colony morphotypes as its parameters. The utility of these cellular interactions for understanding the retention of this bacterium in oyster tissues and its ecology in estuarine environments were demonstrated.

The effect of ultraviolet (UV) depuration was determined on Vibrio vulnificus associated with the oyster Crassostrea virginica. Two hours of UV treatment was bactericidal for pure cultures of the bacterium. In contrast, the bacterium persisted at 1,000 to 10,0000 cells per ml for three days when oysters containing the natural population of bacterium were present in the depurated seawater. After three days of UV treatment, the bacterial distribution increased progressively in the mantle, hemolymph and digestive tract. A temperature of 15 degrees centigrade was found inhibitory both in seawater and oyster tissues treated and untreated with UV.

The behavior of Bacillus anthracis Strene spores in sterile raw ground beef is measured at storage temperatures 2 to 70 degree centigrade, which has encompassed both bacterial growth and death. The inability of Bacillus anthracis to grow between 2 and 16 degree centigrade and inactivation at high temperatures might reduce the risk for recommended ground-beef handling and preparation procedures.

The interactions between Escherichia coli O157:H7 and the gastric environment, including comparisons with Shigella spp. are reported. In order to understand the kinetics of Escherichia coli O157:H7 survival in gastric fluid, individual Escherichia coli O157:H7 were suspended in various media mixed at various proportions with simulated human gastric fluid and then, incubated at 37 degree Celsius for up to 4 h.

Results indicate that ribotyping with a single restriction enzyme HindIII is not an effective method to differentiate Escherichia coli isolates within the same species or in samples collected from different geographical regions. However, the method differentiates E. coli from human or animal sources derived from a large geographic region.