We studied the protective effect of subcutaneous immunization with Trichomonas vaginalis in a mouse model of vaginal infection. BALB/c mice were immunized with various doses of T. vaginalis (4.5 ؋ 10 5 , 9 ؋ 10 6 , and 1 ؋ 10 8 organisms per ml) suspended in Freund's complete adjuvant 56 days prior to vaginal infection and were given booster injections of the same doses of T. vaginalis in Freund's incomplete adjuvant 4 weeks later. Control mice were immunized and given booster injections of phosphate-buffered saline suspended in Freund's complete and incomplete adjuvants. The mice were tail bled and vaginal washes were performed at weekly intervals for 4 weeks to determine the isolation of T. vaginalis and the serum and vaginal antibody reactivity. Mice which had been immunized and given booster immunizations had significantly fewer intravaginal infections and had increased serum and vaginal antibody responses compared with those of control mice (P < 0.01). Mice that were vaginally infected, treated with metronidazole, and then reinfected vaginally did not develop protective immunity. Subcutaneous immunization with whole T. vaginalis organisms appears to confer protection against intravaginal challenge with T. vaginalis, protection which is not achieved as a result of prior vaginal infection.

Trichomonas vaginalis infection is the most commonly encountered sexually transmitted disease. There is a need for more accurate and rapid laboratory diagnostic methods, leading to better control and treatment strategies. Various virulence factors such as adherence, contact-independent factors, hemolysis and acquisition of host macromolecules have been shown to play a role in the pathogenesis of this infection. Detection of the factors that are only present in the pathogenic isolates of trichomonads will lead to a better understanding of the epidemiology of this pathogen. Culture technique is highly specific compared with microscopic techniques, but it is time consuming. Immunological techniques lack proper correlation with clinical manifestations. The application of monoclonal antibodies, either singly or in a group that recognizes a common antigen, along with methods such as detection of common DNA fragment from clinical specimens, may have a promising future in the laboratory diagnosis of trichomoniasis.

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The effect of typical sanitizers on the composition and toxicity of lipopolysaccharides (LPSs) produced by Salmonella Enteritidis ATCC 13076 was analyzed. Salmonella Enteritidis was propagated up to the late exponential phase in the presence of commercial sanitizing solutions. LPS was extracted and derivatized with trifluoroacetylation, and gas chromatography-mass spectrometry analysis and the chromogenic Limulus amoebocyte lysate assay were used to assess the ultrastructure and toxicity of the LPS. The viability and debris formation during growth were evaluated to verify the bactericidal and bacteriostatic effects of the sanitizers and to assess sanitizer effects on LPS formation. The LPSs produced were quantified at 1.7 x 10(4), 1.2 x 10(4), 3.6 x 10(3), and 9.6 x 10(4) [KDO] x OD(620nm)(-1) for the controls and the organisms grown in the presence of a chlorinated sanitizer, a heavy-duty alkaline cleaner, and a phenolic hand wash solution, respectively. In response to these treatments, the short-chain polysaccharide fractions of the LPSs in the Salmonella Enteritidis cells increased. This finding suggests that this organism increases the low-molecular-weight fraction of the LPS in relation to the high-molecular-weight fraction to survive these unfavorable conditions. The cumulative change in the LPS in response to the sanitizers influenced the toxicity of the LPS; however, this change could not be related to an individual compound within any of the assessed fractions.

Purpose -This paper aims to evaluate the influence of pasteurization, ultra high temperature (UHT) treatment and sodium benzoate preservation on the LPS-related endotoxicity of food-borne pathogens Escherichia coli, Salmonella enteritidis and Pseudomonas aeruginosa. Design/methodology/approach -The paper sees that selected bacteria were subjected to laboratory simulations of commercially used heat treatments. In the case of sodium benzoate preservation, the bacteria were grown in the presence of a sub-lethal dose of this preservative. Cells and debris were subjected to LPS extraction, GC-MS analyses and endotoxicity measurement with the chromogenic Limulus Amebocyte Lysate (LAL) assay. Findings -The heat treatments and preservation method influenced the LPS-related toxicity of each organism in a different manner. Increases in LPS-related toxicity were noted in the LPS liberated from UHT-treated E. coli and S. enteritidis and pasteurized E. coli and P. aeruginosa. Toxicity of the membrane associated LPS of UHT-treated E. coli and pasteurized S. enteritidis was also elevated. Sodium benzoate resulted in E. coli cells with LPS with related toxicity levels almost double compared to that of the control cells. S. enteritidis LPS also demonstrated an increase in toxicity, while that of P. aeruginosa was rendered less toxic. Practical implications -Toxicity could still be detected even after sterilization treatments like UHT, suggesting that viability and toxicity are not necessarily connected and that the toxicity of LPS molecules that remain in food products after treatment should be considered. Although ingestion of LPS originating from Gram-negative bacteria is a fairly new concept, the effect that these toxins might have on members of society with compromised immune systems and individuals suffering from gastrointestinal diseases cannot be ignored. Originality/value -The paper introduces a unique insight into food safety treatment-induced toxicological changes related to LPS originating from food-borne organisms, a factor that is currently unexplored in the South African food industry.