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Biomedical subjects

S Quessy

Publications and source records attributed to S Quessy.

At least 19 recordsLinked to original sources
PubMed2001

Development of an ELISA procedure to detect swine carriers of pathogenic Yersinia enterocolitica.

An enzyme immunoassay (ELISA) was developed to detect antibodies in pigs against the lipopolysaccharidic antigen of the three serotypes of Yersinia enterocolitica mostly associated with human infections. Recent epidemiological evidence has demonstrated that pigs and pork are important sources of yersiniosis in humans. The purpose of this study was to clarify the use of an ELISA to detect swine carriers of this enteroinvasive bacteria by examining seroconversion and tissue distribution of Y. enterocolitica following experimental infection and then screening pigs at a slaughterhouse by bacterial culture and ELISA. It was observed that seroconversion occurred in animals experimentally inoculated with Y. enterocolitica but not with other enterobacteria. It was also found that 27% of swine at a slaughterhouse carried the bacterium in their tonsils and/or intestinal tract, whereas 66% showed serological evidence of previous infection. About 6% of swine at slaughter were culture-positive, but seronegative. Although, similar numbers of swine showed serological evidence of previous infection by each of the three Y. enterocolitica serotypes tested, virtually all culture isolates belonged to serotype O:3. This ELISA appears as a valuable control tool that can be used, in conjunction with culture, to identify pigs or herds infected by strains of Y. enterocolitica associated with human infections.

Abattoirs↗
PubMed2001

Trends in antimicrobial resistance of Salmonella isolated from animals, foods of animal origin, and the environment of animal production in Canada, 1994-1997.

The purpose of our study was to determine the occurrence, magnitude, trends, and relationships regarding antibiotic resistance of Salmonella isolated from animals, animal food products, and the environment of animals. We examined 621 strains of 67 different serovars isolated in 1994, 721 strains of 75 different serovars isolated in 1995, 1,219 strains of 83 different serovars isolated in 1996, and 1,336 Salmonella strains of 92 different serovars isolated in 1997, for resistance to 17 antibiotics at one to three different concentrations with the agar dilution method. The overall resistance magnitude regressed from 9.2% in 1994 to 8.1% in 1997. Resistance to streptomycin (30.4% of 3,897 isolates), tetracycline (27.3%), and sulfisoxazole (23.7%) was highest. Resistance to streptomycin, tetracycline, kanamycin, and gentamicin declined during the 4-year period. Notable increases in resistance to ampicillin, chloramphenicol, and neomycin occurred during the 1994-1997 years. None of the isolates was resistant to amikacin. None of the isolates was resistant to ciprofloxacin at 1, 2, and 4 microg/ml. Salmonella bredeney isolates from turkeys showed a decreased sensitivity to ciprofloxacin and were resistant at the low level of 0.125 microg/ml, but none of these isolates was resistant at 1 microg/ml. Resistance to nalidixic acid correlated significantly with decreased sensitivity to ciprofloxacin; 122 of 127 (96%) isolates resistant to nalidixic acid at 32 microg/ml were resistant to ciprofloxacin at 0.125 microg/ml but sensitive at 1 microg/ml. Resistance to S. typhimurium to each of the seven antibiotics ampicillin, chloramphenicol, kanamycin, neomycin, streptomycin, sulfisoxazole, and tetracycline increased persistently during each of the years 1994-1997, but none of the S. typhimurium isolates showed decreased sensitivity to ciprofloxacin. Clinical isolates of Salmonella were twice as frequently resistant to the antimicrobials in the test panel than isolates obtained during surveys. Salmonella isolates from turkeys were more frequently resistant than isolates from pigs, cattle, and chickens.

Animal Population Groups↗
PubMed2001

Phenotypic and genotypic characterization of Escherichia coli verotoxin-producing isolates from humans and pigs.

The aim of this study was to characterize verotoxin-producing Escherichia coli (VTEC) isolates obtained from humans and pigs in the same geographic areas and during the same period of time in order to determine whether porcine VTEC isolates could be related to human cases of diarrhea and also to detect the presence of virulence factors in these isolates. From 1,352 human and 620 porcine fecal samples, 11 human and 18 porcine verotoxin-positive isolates were obtained by the VT immunoblot or the individual colony testing technique. In addition, 52 porcine VTEC strains isolated from diseased pigs at the Faculté de médecine vétérinaire during the same period or from fecal samples collected previously isolated at slaughterhouses were characterized in this study. Antimicrobial resistance profiles were different between human and porcine isolates. In general, the serotypes observed in the two groups were different. No porcine isolate was of serotype O157:H7; however, one isolate was O91:NM, a serotype that has been associated with hemorrhagic colitis in humans. Also, one serotype (O8:H19) was found in isolates from both species; however, the O8:H19 isolates of the two groups were of different pathotypes. The pathotypes observed in the human and porcine isolates were different, with the exception of VT2vx-positive isolates; the serotypes of these isolates from the two groups were nevertheless different. Pulsed-field gel electrophoresis analysis indicated no relatedness between the human and porcine isolates. In conclusion, these results suggest that the porcine and human isolates of the present study were not genetically related. Most porcine VTEC isolates did not possess known virulence factors required to infect humans. However, certain non-O157:H7 porcine VTECs may potentially infect humans.

Animals↗
PubMed2001

Classification of grossly detectable abnormalities and conditions seen at postmortem in Canadian poultry abattoirs according to a hazard identification decision tree.

This study was designed to review all grossly detectable abnormalities and conditions (GDACs) encountered in poultry in Canadian abattoirs to determine which have potential to cause adverse health effects for the consumer. Review of the literature and consultation with scientists in the field of microbiology, epidemiology, poultry pathology, chemistry, and meat inspection served to generate an inventory of GDACs, and a decision tree containing algorithms was developed to identify GDACs potentially representing a health hazard to consumers. Through the use of the decision tree, GDACs were classified into different categories with regard to the risk they represent to humans. A number of GDACs were identified as being of potential concern from a food safety perspective, namely Erysipelas, fowl cholera, Campylobacteriosis, clostridial diseases, hepatitis/enteritis associated with Helicobacter, Listeriosis, Salmonella infections (nontyphoid infections, Salmonella arizonae, pullorum disease, and fowl typhoid), Staphylococcosis, and Toxoplasmosis. Further characterization--i.e., hazard characterization, exposure assessment, and risk characterization--is required to quantify or better characterize the probability that products derived from affected carcasses may affect the consumer as well as the resulting consequences. Risk assessment is a dynamic process. Results presented in this paper are based on available information and expert opinion. As new information is obtained, the inventory of GDACs and their classification may be modified.

Abattoirs↗
PubMed2001

Decrease of the adhesion of Streptococcus suis serotype 2 mutants to embryonic bovine tracheal cells and porcine tracheal rings.

Streptococcus suis is an important swine pathogen that may be present in the tonsils of pigs that show no signs of illness. Because adhesion to host cells may be important in the carrier state, this study was undertaken to investigate adhesion to host cells by S. suis mutant strains defective in expression of a 39-kDa protein. Mutant strains of S. suis were generated by transposon Tn916 mutagenesis and were tested for adhesion to embryonic bovine tracheal cells and porcine tracheal rings. Compared with the parent strain, there was a significant reduction in adherence of 3 mutant strains to both bovine tracheal cells and porcine tracheal rings.

Animals↗
PubMed2001

Host response to various treatments to reduce Salmonella infections in swine.

Host response was evaluated following the administration of various treatments, such as probiotics, prebiotics, and vaccination, to reduce Salmonella in swine. Response to the treatments were studied by the evaluation of phagocytosis rates by flow cytometry, by studying the activation of whole-blood phagocytes by bioluminescence, the production of IgA against S. Typhimurium, and by histopathology. Significant differences were observed in the activation of whole-blood phagocytes in all groups of treated pigs (P = 0.0001). In SC54 vaccinated pigs, a significant reduction of Salmonella in the ileum was observed (P < 0.05) and the production of IgA against S. Typhimurium was higher in this group in comparison to uninfected control pigs (P = 0.0007). Furthermore, significant histopathological (P < 0.05) changes were observed in SC54 vaccinated pigs. Villus height and mucus and goblet cells density in the small intestine were reduced in vaccinated pigs in comparison to infected control pigs. Taken together, these findings suggest that SC54 vaccine can stimulate local immunity and reduce the presence of Salmonella in the ileum in swine. Use of SC54 vaccine should thus be considered in further field experiments.

Animals↗
PubMed2000

Evaluation of the hygienic performances of the processes for cleaning, dressing and cooling pig carcasses at eight packing plants.

The hygienic performances of the processes for the production of cooled carcasses at eight pork packing plants were assessed from small sets of microbiological data. At each plant, a single sample was obtained from a randomly selected site on each of 25 randomly selected carcasses at each of three stages of processing, which were after polishing, after washing at the end of the dressing process, and after cooling. The aerobic bacteria, coliforms and Escherichia coli recovered from each sample were enumerated. When bacteria of one type were recovered from > or = 20 of 25 samples, the log mean number of those bacteria on the population of carcasses undergoing processing was estimated on the assumption that the set of counts was normally distributed. The log of the total number recovered from 25 samples was calculated for each set of counts. The log mean numbers of total aerobic bacteria recovered from the polished carcasses at different plants ranged from about 1.9 to 3.8 log cfu cm(-2). At six of the plants, the log mean numbers of total aerobes on the cooled carcasses did not differ substantially from the log mean numbers on the polished carcasses, but the log mean numbers on the cooled carcasses were substantially higher at one plant and substantially lower at another than on the polished carcasses. Coliforms and E. coli were recovered from too few samples in most sets from cooled carcasses for estimation of their log mean numbers. However, the log total numbers of coliforms and E. coli recovered indicated that substantial numbers of those organisms were added to carcasses during the dressing processes at four of the plants, and that the numbers on the carcasses were substantially reduced by the processes for cooling without spraying at two of the plants. At seven of the plants, the total numbers of coliforms and E. coli recovered from cooled carcasses were <3.1 and <2.2 log cfu 2500 cm(-2), respectively. The findings indicate that production processes for pig carcasses can be operated to give cooled carcasses with log mean numbers of total aerobes < 2 cm(-2), and log total numbers of coliforms and E. coli each < 1 2500 cm(-2).

Animals↗
PubMed2000

Assessment of various treatments to reduce carriage of Salmonella in swine.

In this study, different strategies to reduce carriage of Salmonella spp. in pigs were evaluated. Probiotics, prebiotics, vaccination, and acidification of drinking water were assessed as means of reducing Salmonella. Acidification of water, use of egg yolk-specific immunoglobulins, and vaccination with an endotoxin vaccine did not reduce Salmonella excretion in experimentally infected pigs. A reduction of Salmonella in the colonization of mesenteric lymph nodes was observed with the use of bambermycins and a live attenuated vaccine. A reduction in the shedding of S. Typhimurium was also observed after supplementation with fructooligosaccharides in drinking water. The use of probiotics and prebiotics appeared to change the pig fecal bacterial flora as indicated by Gram staining of smears from rectal swabs.

Animals↗
PubMed2000

Epidemiological study of Yersinia enterocolitica in swine herds in Québec.

The objectives of this study were the identification of the different contamination sources of Yersinia enterocolitica, as well as the determination of the prevalence and the distribution of the different genotypes in swine herds. The owners of 20 farms, located in the Richelieu-Yamaska region, agreed to participate in the study. Each farm was visited a minimum of 5 times between May and October 1997, and, at each visit, 20 environmental and 10 fecal samples were collected. Yersinia enterocolitica isolates were identified, serotyped, and submitted to a genetic characterization by pulsed-field gel electrophoresis. The correlation coefficient (0.61) between prevalence in environment and in feces was significant (P = 0.004). Among the 153 positive samples, 93.5% belonged to serotype 0:3. The comparison of PFGE profiles revealed that all environmental Y. enterocolitica isolates had a profile identical to that of isolates recovered in feces from the corresponding farms. Also, when the genetic profiles of isolates recovered from feces collected at the first visit were compared with the profiles of isolates obtained from the subsequent visits, the same profile was observed on every farm. We concluded that environment does not represent the main source of contamination of swine by Y. enterocolitica and that, in most instances, the same strain persists in a barn from one production lot to another.

Animal Husbandry↗
PubMed1999

Distribution of Salmonella in swine herds in Québec.

Five porcine finishing units, previously identified as contaminated by Salmonella, were sampled to identify possible sources of contamination and to study the distribution of Salmonella within the herds. A total of 208 environmental samples were taken and 87 samples (42%) were found contaminated by Salmonella spp. Salmonella was recovered from several types of samples. Among these, fecal material from pens, building environment such as doors, floors, ventilation units, dust and farm accessories were most often found positive. Some of the flies and rodents were also positive. Two of the finishing units were part of an integrated production system and the prevalence and distribution of Salmonella spp. at different production steps of the integrated facilities were studied. Forty-one farms were sampled and a total of 1923 faecal samples in randomly selected pens were analysed. One hundred and fifty-one samples (7.9%) were positive for Salmonella spp. Among the farms sampled, 70.7% (29/41) were positive for isolation of Salmonella. The different levels in the integrated production were unevenly contaminated. Replacement sow (15.9%) and finishing unit for gilts (21.9%) were the most contaminated levels. Ten serotypes of Salmonella (n = 132) were identified in the production pyramid with a predominance of Salmonella Derby (37.1%) and Salmonella Typhimurium (34.1%). Pulse Field Gel Electrophoresis analysis of the various isolates from serotypes and Salmonella Typhimurium, Salmonella Derby and Salmonella Anatum showed no variation in the genetic profiles, within each serotype, suggesting a vertical contamination throughout the different production steps.

Agglutination Tests↗
PubMed1999

Prevalence of Salmonella spp. and Yersinia enterocolitica in finishing swine at Canadian abattoirs.

The prevalence of Salmonella spp. and Yersinia enterocolitica in finishing swine was evaluated using samples of cecal material. Samples were taken at six different slaughterhouses from 1420 healthy, 5-month-old pigs, raised by 223 producers in Quebec (1009 samples), Ontario (283), and Manitoba, Canada (128). Two different broth media (Rappaport-Vassiliadis and Tetrathionate brilliant green) were used for the selective enrichment of Salmonella spp. The recovery of Y. enterocolitica was done by a cold enrichment technique, followed by plating on a selective media (cefsulodin-irgasan-novobiocin agar). Prevalence (with a 95% confidence interval) of Salmonella spp. and Y. enterocolitica were, respectively, 5.2% (4.0 to 6.4%) and 20.9% (18.8 to 23.0%). Overall, 24.6% of the animals tested were positive for one or both of these pathogens. Since only a few herds (2.8%) appeared to be highly contaminated by Salmonella spp., efforts should be undertaken in priority to control this pathogen in those herds.

Abattoirs↗
PubMed1999

Characterization of the risk to human health of pathogenic Escherichia coli isolates from chicken carcasses.

The purpose of this study was to evaluate the risk for human health associated with pathogenic Escherichia coli isolated from airsacculitis and cellulitis in chickens, by comparing the genotypic and phenotypic profiles of avian E. coli isolates and E. coli strains isolated from sick humans during the same period and in the same geographical area as the avian isolates. A total of 96 isolates and 46 isolates from lesions of cellulitis and airsacculitis, respectively, were obtained. Isolates from the backs of some of the affected and healthy birds and 91 intestinal and extraintestinal isolates from humans with diarrhea, urinary tract infections, or septicemia were examined. The frequency of antimicrobial resistance was in general higher in the avian than in the human isolates. VT1-VT2-Eae and VT2-Eae, pathotypes associated with hemolytic and uremic syndrome and bloody diarrhea in humans, were the most frequently encountered pathotypes in human intestinal isolates but were not recovered from the avian isolates. Aero-Pap-TSH and Aero-TSH were the most frequently encountered pathotypes in avian isolates but were rarely observed in human isolates. No avian isolate was of serogroup O157, whereas many human isolates belonged to this O group. O78 and O2 were the most frequently observed O groups in avian isolates but were rarely found in human isolates. Only two avian isolates demonstrated possible relatedness to human isolates based on pulsed-field gel electrophoresis profiles, but they belonged to different pathotypes. Our results suggest that avian isolates recovered from cellulitis and air sacullitis possess very few of the attributes required to cause diseases in humans. It is also concluded that isolates from cellulitis and airsacculitis do not represent a greater hazard than isolates from the back of healthy birds.

Air Sacs↗
PubMed1999

[Monitoring of microbial contamination of stick wound in swine carcasses].

This study was done to evaluate the microbial contamination by Salmonella spp., Escherichia coli, fecal coliforms, and total aerobic count of the stick wound of swine carcasses. The effectiveness of trimming the stick wound in the 2 Québec slaughterhouses visited was evaluated. A bacteriological analysis was done on 276 stick wounds. Results indicated that, before trimming, 0.9% stick wounds were contaminated by Salmonella spp. Contamination by coliforms was observed in 40.6% of samples, and 27.7% were positive for E. coli. After trimming the stick wounds, 1.1% were contaminated by Salmonella spp., 34.1% were contaminated by coliforms, and 26.2% were positive for E. coli. The results showed that trimming contributes to reducing significantly the bacterial total count at the site and that the bacterial load at this site was less important than that found on the brisket.

Abattoirs↗
PubMed1999

Presence of Yersinia enterocolitica in tissues of orally-inoculated pigs and the tonsils and feces of pigs at slaughter.

In order to study the early events associated with infection of swine by Yersinia enterocolitica, 42 five-week-old crossbred piglets were inoculated per os with approximately 10(8) Y. enterocolitica O:3. Groups of 5 animals (and one negative control) were euthanized 30 min, 3, 6, 12, 24, 48 and 72 h following the infection. Palatine tonsils, retropharyngeal and mesenteric lymph nodes, esophagus, duodenum, jejunum, ileum (and Peyer's patches), stomach, liver, spleen and feces (from colon) were collected and analyzed for the presence of Y. enterocolitica by standard bacteriological procedures. Natural infections were also analyzed, as a complementary study, by taking one-gram samples of fecal material and tonsils from 291 pig carcasses less than 3 h after slaughter and culturing them for Y. enterocolitica using a cold enrichment technique. Within 30 min, Yersinia enterocolitica O:3 was already present at most sites. The presence of Y. enterocolitica in the liver of 3 out of 10 animals and also in the spleen of 3 out of 10 piglets, within the first 3 h postinfection, but not at later times (with one exception), probably indicated a transient bacteremia accompanying the initial stages of infection. The tonsils were colonized in most animals (13/20) as the bacteria remained present from 12 to 72 h postinfection, while only 4 out of 20 fecal samples were found to be positive over the same period. Up to 10(4) colony-forming units of Y. enterocolitica per gram of tonsil and fecal material were recovered. Finally, among the 291 animals sampled at the abattoir, a total of 79 were found positive, 70 of the tonsils sampled were positive, and bacteria were recovered in 17 fecal samples. It is therefore suggested that palatine tonsils are the most reliable tissue for the indication of an infection/colonization by Y. enterocolitica O:3 in swine and that the removal of this tissue during the slaughter process should be considered in order to minimize the possibility of contamination of meat products.

Abattoirs↗
PubMed1999

[Comparison of host water wash and trimming of pork carcasses for reducing the level of bacterial contamination].

This study was carried out to evaluate the microbial contamination on pork carcasses after they had fallen on the floor in the cooler and also to evaluate the effectiveness of trimming and hot, high-pressure water washing (55 degrees C). A bacteriological analysis was done on 2 groups of 40 carcasses before and after trimming or washing, along with a group of 10 control carcasses. Results showed that the bacterial total count was higher (P = 0.01) on carcasses after they had fallen, but, in this study, no significant difference (P = 0.76) was found for total coliform contamination. Also, no significant difference was observed between total count for aerobic bacteria, total coliforms, and Escherichia coli before and after decontamination, no matter which technique was used. Neither trimming nor washing carcasses showed, in this study, a significant difference (P = 0.37) in the reduction of the total aerobic bacterial count on the pork carcasses analyzed (P = 0.65).

Animals↗
PubMed1998

Simultaneous flow cytometric measurement of Streptococcus suis phagocytosis by polymorphonuclear and mononuclear blood leukocytes.

A simple flow cytometric method was used to study simultaneously the phagocytosis of Streptococcus suis serotype 2 by polymorphonuclear and mononuclear blood leukocytes from swine and humans. Using this method with a bacteria-to-leukocytes ratio of 10:1 and after 60 min of incubation, 80.2 +/- 2.8% of swine granulocytes and 77.0 +/- 2.8% of swine monocytes were shown to contain FITC-labelled S. suis serotype 2 strain 735. Using the same strain, FITC-labelled bacteria were found in 95.5 +/- 3.2% of human granulocytes and in 92.8 +/- 3.6% of human monocytes. The phagocytosis rates of avirulent and virulent strains of S. suis were not significantly different.

Animals↗
PubMed1997

Description of an albumin binding activity for Streptococcus suis serotype 2.

This study was undertaken to investigate the binding activity of Streptococcus suis serotype 2 to albumin. Using flow cytometry we observed a binding activity of S. suis to albumin for virulent as well as for avirulent isolates. Western immunoblots analysis revealed that a 39-kDa S. suis protein was responsible, at least in part, for this binding activity. This protein showed high N-terminal homology (95.6% for the first 23 residues) with a group A Streptococcus glyceraldehyde-3-phosphate dehydrogenase. Furthermore, the addition of albumin to the culture broth resulted in an increase in the virulence of S. suis strains in mice. These results suggest that an interaction with albumin could play a role in the pathogenesis of S. suis serotype 2 infections.

Albumins↗