The halophilic bacterium Vibrio fluvialis is an enteric pathogen that produces an extracellular hemolysin. This hemolysin was purified to homogeneity by using sequential hydrophobic-interaction chromatography with phenyl-Sepharose CL-4B and gel filtration with Sephacryl S-200. It has a molecular weight of 63,000 and an isoelectric point of 4.6, and its hemolytic activity is sensitive to heat, proteases, and preincubation with zinc ions. The hemolysin lyses erythrocytes of the eight different animal species that we tested, is cytotoxic against Chinese hamster ovary cells in tissue culture, and elicits fluid accumulation in suckling mice. Lysis of erythrocytes occurs by a temperature-dependent binding step followed by a temperature-and pH-dependent lytic step. Fourteen of the first 20 N-terminal amino acid residues (Val-Ser-Gly-Gly-Glu-Ala-Asn-Thr-LeuPro-His-Val-Ala-Phe-Tyr-Ile-Asn-Val-Asn-Arg) are identical to those of the El Tor hemolysin of Vibrio cholerae and the heat-labile hemolysin of Vibrio mimicus. This homology was further confirmed by PCR analysis using a 5 primer derived from the amino-terminal sequence of the hemolysin and a 3 primer derived from the El Tor hemolysin structural gene. The hemolysin also reacts with antibodies to the El Tor-like hemolysin of non-O1 V. cholerae.Vibrio fluvialis is a halophilic bacterial pathogen that has been isolated from humans with diarrhea and from river and estuarine water, marine mollusks, crustaceans, and fish. It has been implicated in outbreaks and sporadic cases of diarrhea, and gastrointestinal illness caused by this pathogen is usually associated with consumption of raw or improperly cooked seafood. In the United States, recent data show that it was responsible for 82 of the 1,584 Vibrio infections reported to the Centers for Disease Control and Prevention since 1997 (M. C. Evans, P. M. Griffin, and R. V. Tauxe, CDC report: Vibrio surveillance system, summary data, 1997-2000 [http://www.cdc.gov /ncidod/dbmd/diseaseinfo/files/CSTE_Vibrio_2000.pdf]). Clinical symptoms of gastroenteritis caused by V. fluvialis and Vibrio cholerae are very similar, and therefore the ability of V. fluvialis to cause diarrhea has been examined in various animal models originally designed for V. cholerae. V. fluvialis elicits intestinal fluid when fed to suckling mice (18, 23) and in rabbit ileal loops (5, 25). It produces a toxin that elongates Chinese hamster ovary (CHO) cells, a nonhemolytic CHO cell-killing cytotoxin, a protease, and a cytolysin active against rabbit erythrocytes (5, 17). Lockwood et al. (18) showed that partially purified preparations of the elongation factor, protease, and cytolysin/hemolysin induced fluid accumulation in suckling mice. However, it is not clear what roles these products play in diarrheal disease since none of them have been purified. In their research with the V. fluvialis hemolysin (VFH), Rahim and Aziz (26) reported that of the six different growth media tested, brain heart infusion broth yielded maximal amounts of hemolysin. In order to ha...
This study investigated the sources of two foodborne pathogens, Salmonella and Campylobacter in a commercial swine production system. Pathogens were characterized using conventional culture and isolation techniques and antibiograms. Four swine herds were selected and followed from late nursery to slaughter along with the four truck washes servicing the system. Increase in Salmonella prevalence with increasing age from late nursery to slaughter was found. Prevalence of Campylobacter fluctuated in different age groups throughout the production period. All truck washes, except truck wash D, showed a reduction in contamination from pre to post wash. It was found that trucks remain a potential source of Salmonella and Campylobacter even after washing and disinfection. The type and extent of multi-drug resistance varied by stage of production and environmental source. Genotypic profiling is underway to determine the clonality of isolates from pigs, trucks and environmental samples to better characterize important sources of cross contamination.
The main objective of this study was to develop a rapid, sensitive and accurate real-time detection assay for multi-drug resistant (MDR) Salmonella strains isolated from pigs. Initially, standardized procedures for use with real-time PCR using SYBR ® green were developed to evaluate selected primers, detection limitations using two predominant strains: S. Typhimurium phage types DT104 and DT193. The use of bacterial lysate and purified DNA samples was also compared. Lysate dilutions for concentrations (100-10-5) resulted in widely varied amplification as reflected in amplification curves. In contrast, purified DNA samples diluted to 10-8 µg/mL resulted in lower threshold cycles thus was found to be a more reliable procedure. The low detection limit and therefore, increased sensitivity of real-time PCR suggests this technology could be the cornerstone for development of assays for potential use on farms, in slaughter facilities, and by veterinarians in field efforts to detect pathogens in biological samples before organisms cause foodborne illness in humans.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.