Molecular typing and resistance analysis of travel-associated Salmonella enterica serotype Typhi.

Salmonella enterica serotype Typhi is a human pathogen causing 12 to 30% mortality and requiring antibiotic therapy to control the severity of the infection. Typhoid fever in United States is often associated with foreign travel to areas of endemicity. Increasing resistance to multiple drugs, including quinolones, is associated with decreased susceptibility to ciprofloxacin (DCS). We investigated 31 clinical strains isolated in Florida from 2007 to 2010, associated with travel to six countries, to examine the clonal distribution of the organism and apparent nalidixic acid (NAL) resistance. The strains were isolated from blood or stool of patients aged 2 to 68 years. The isolates were subtyped by ribotyping and pulsed-field gel electrophoresis. Susceptibilities to 15 antimicrobials were determined, and the isolates were screened for integrons and gyrase A gene mutations. Both typing techniques effectively segregated the strains. Identical clones were associated with different countries, while diverse types coexisted in the same geographic location. Fifty-one percent of the strains were resistant to at least one antimicrobial, and five were resistant to three or more drugs (multidrug resistant [MDR]). All 12 isolates from the Indian subcontinent were resistant to at least one drug, and 83% of those were resistant to NAL. Three of the MDR strains harbored a 750-bp integron containing the dfr7 gene. Ninety-three percent of the resistant strains showed a DCS profile. All the NAL-resistant strains contained point mutations in the quinolone resistance-determining region of gyrA. This study affirms the global clonal distribution, concomitant genetic heterogeneity, and increased NAL resistance of S. enterica serovar Typhi.

Consumption of Raw Flour in the United States: Results from the 2019 U.S. Food and Drug Administration Food Safety and Nutrition Survey.

ABSTRACT: Several outbreaks of Shiga toxin-producing Escherichia coli infections in the past decade have been linked to flour and flour-associated products and have raised concerns that the consumption of raw flour represents a public health risk as a vehicle for foodborne pathogens. The extent to which consumers know and understand that they should not consume raw flour is unclear. In fall 2019, the U.S. Food and Drug Administration collected data on perceptions regarding uncooked flour and on self-reported consumption behaviors via the Food Safety and Nutrition Survey, a national probability survey of U.S. adults (≥18 years of age). Cross-tabulations and regressions were used to analyze the data (n = 2,171). Thirty-five percent of consumers reported having tasted or eaten something with uncooked flour in it in the previous 12 months. Responses differed significantly by sex, race, education, and age. On average, respondents indicated that uncooked flour is not likely to contain germs that can make people sick, with significant differences noted by demographic categories. Respondents rated raw homemade cookie dough as moderately likely to have germs that can make people sick, with significant demographic differences. These findings indicate that U.S. consumers are largely unaware that raw flour is risky to consume, and many people are consuming products that contain raw flour.

Real-time PCR detection of Salmonella species using a novel target: the outer membrane porin F gene (ompF).

AIMS: To evaluate the outer membrane porin F gene (ompF) for the specific detection of Salmonella species by real-time PCR assay. METHODS AND RESULTS: Two hundred and eighteen isolates belonging to Salmonella enterica (subspecies I-VI) and Salmonella bongori were examined using primers designed to detect the ompF gene. The DNA of the bacteria was extracted from pure culture. The target was present in all the 218 Salmonella isolates including all the subspecies of Salm. enterica and Salm. bongori. The ompF gene was absent in 180 non-Salmonella strains tested. The limit of detection was determined to be three colony forming units per reaction in pure culture. In artificially contaminated food experiments with ten or less colony forming units per 25 g, the assay was successful in identifying the target in 100% of the samples after 22- to 24-h incubation in enrichment broth. CONCLUSIONS: Based on this study, the ompF gene is 100% inclusive for Salmonella species and 100% exclusive for non-Salmonella species for the strains tested. SIGNIFICANCE AND IMPACT OF THE STUDY: ompF gene was present in all the Salmonella strains tested and has the potential to be a good target for the rapid molecular identification of Salmonella.