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P Desmarchelier

Publications and source records attributed to P Desmarchelier.

16 recordsLinked to original sources
PubMed2004

Enumeration of Escherichia coli O157 in cattle faeces using most probable number technique and automated immunomagnetic separation.

AIMS: To determine the numbers of Escherichia coli O157 present in the faeces of naturally infected cattle. METHODS AND RESULTS: A combination of the most probable number (MPN) technique and automated immunomagnetic separation (AIMS) was used to enumerate E. coli O157 in cattle faeces from both pasture-fed and grain-fed animals. A total of 22 E. coli O157 positive faecal samples were enumerated for E. coli O157 (10 from pasture-fed and 12 from grain-fed animals). The numbers of E. coli O157 in cattle faeces varied from undetectable (<3 MPN g-1 of faeces) to 2.4 x 104 MPN g-1. There was no significant difference (P = 0.06) between the numbers of E. coli O157 in pasture-fed or grain-fed cattle faeces, although the geometric mean (antilog of the mean of log10 transformed MPN values) was higher in grain-fed (130 MPN g-1) than in pasture-fed (13 MPN g-1). CONCLUSIONS: Although the number of samples tested is small, the results indicate that E. coli O157 make up a small proportion of the total E. coli population present in cattle faeces. SIGNIFICANCE AND IMPACT OF THE STUDY: Information on the numbers of E. coli O157 present in cattle will assist in developing more robust quantitative risk assessments and formulating intervention strategies.

Animal Feed↗
PubMed2004

The prevalence and concentration of Escherichia coli O157 in faeces of cattle from different production systems at slaughter.

AIMS: To determine the prevalence and concentration of Escherichia coli O157 shed in faeces at slaughter, by beef cattle from different production systems. METHODS AND RESULTS: Faecal samples were collected from grass-fed (pasture) and lot-fed (feedlot) cattle at slaughter and tested for the presence of E. coli O157 using automated immunomagnetic separation (AIMS). Escherichia coli O157 was enumerated in positive samples using the most probable number (MPN) technique and AIMS and total E. coli were enumerated using Petrifilm. A total of 310 faecal samples were tested (155 from each group). The geometric mean count of total E. coli was 5 x 10(5) and 2.5 x 10(5) CFU g(-1) for lot- and grass-fed cattle, respectively. Escherichia coli O157 was isolated from 13% of faeces with no significant difference between grass-fed (10%) and lot-fed cattle (15%). The numbers of E. coli O157 in cattle faeces varied from undetectable (<3 MPN g(-1)) to 1.1 x 10(5) MPN g(-1). Twenty-six (67%) of 39 O157 positive faeces had <10 MPN g(-1) and three (8%) had counts between 10(3)-10(5) MPN g(-1). There was no significant difference between concentrations of E. coli O157 in the faeces of grass-fed or lot-fed cattle. CONCLUSION: The prevalence and numbers of E. coli O157 in the faeces of cattle at slaughter were not affected by the production systems evaluated in this study. SIGNIFICANCE AND IMPACT OF THE STUDY: Information on the prevalence and numbers of E. coli O157 can be used for formulating intervention strategies and in quantitative risk assessments.

Abattoirs↗
PubMed2004

Quantification and prevalence of Salmonella in beef cattle presenting at slaughter.

AIMS: A survey to determine the prevalence and numbers of Salmonella in beef cattle presented for slaughter at abattoirs across Australia was conducted between September 2002 and January 2003. METHODS AND RESULTS: Automated immunomagnetic separation (AIMS) was used for detection and isolation of Salmonella enriched from cattle faeces. Salmonella were enumerated from positive samples using a combination of the Most Probable Number (MPN) technique and AIMS. A total of 310 faecal samples were tested, 155 were from lot-fed cattle and 155 from grass-fed cattle. Salmonella spp. were isolated from 21 (6.8%) of the cattle and the prevalence amongst grass-fed cattle (4.5%) was not significantly different to that found in lot-fed cattle (9%). Counts of Salmonella in positive faeces varied from <3 MPN g(-1) of faeces to 2.8 x 10(3) MPN g(-1) and 71% of positive samples had counts <10 MPN g(-1) faeces. There was no significant difference in the mean log10 number of Salmonella in faeces of cattle from each production system. CONCLUSION: Low numbers of beef cattle were found to shed Salmonella at the time of slaughter and the prevalence and the associated faecal concentrations did not vary significantly with the pre-slaughter production system (grass or lot feeding). The faecal concentration of Salmonella in the majority of faeces was low (<10 MPN g(-1)) with few high concentrations up to 3 x 10(3) MPN g(-1), suggesting there may be a low risk of carcase contamination. SIGNIFICANCE AND IMPACT OF THE STUDY: Beef cattle do not appear to be a major source of entry of Salmonella into the human food chain and the quantitative information contained in this study can be used in quantitative assessments of the associated risk of human salmonellosis.

Abattoirs↗
PubMed2002

Comparison between human and animal isolates of Shiga toxin-producing Escherichia coli O157 from Australia.

There is very little human disease associated with enterohaemorrhagic Escherichia coli O157 in Australia even though these organisms are present in the animal population. A group of Australian isolates of E. coli O157:H7 and O157:H- from human and animal sources were tested for the presence of virulence markers and compared by XbaI DNA macrorestriction analysis using pulsed-field gel electrophoresis (PFGE). Each of 102 isolates tested contained the gene eae which encodes the E. coli attaching and effacing factor and all but one carried the enterohaemolysin gene, ehxA, found on the EHEC plasmid. The most common Shiga toxin gene carried was stx2c, either alone (16%) or in combination with stx1 (74%) or stx2 (3%). PFGE grouped the isolates based on H serotype and some clusters were source specific. Australian E. coli O157:H7 and H- isolates from human, animal and meat sources carry all the virulence markers associated with EHEC disease in humans therefore other factors must be responsible for the low rates of human infection in Australia.

Animals↗
PubMed2002

Horizontal transmission of Shiga toxin-producing Escherichia coli within groups of dairy calves.

To examine the dissemination of Shiga-toxigenic Escherichia coli (STEC) within cattle groups, dairy calves on two farms utilizing different calf-rearing practices were exposed to a traceable STEC strain. Test strain dissemination differed significantly between farms, with a higher prevalence being associated with group penning. Pen floors and calf hides may be the main environmental mechanisms of transmission. Dairy calf husbandry represents a control point for reducing on-farm STEC prevalence.

Animals↗
PubMed2001

Characterisation and clonal relationships of Shiga-toxigenic Escherichia coli (STEC) isolated from Australian dairy cattle.

A total of 136 Shiga toxin-producing Escherichia coli (STEC) isolated during a longitudinal survey of three Australian dairy farms were examined to determine their virulence factors, serotype and genomic relationships. This study aimed to assess the potential of these STEC to cause disease in humans and to analyse the on-farm ecology of STEC. Virulence factors (stx, eae, ehxA) were used as determinants of potential to be enterohaemorrhagic E. coli (EHEC) and were examined using polymerase chain reaction (PCR). Among the cattle groups tested, calves, both before and during weaning, shed the most putative EHEC and were the main source of serotypes commonly associated with human disease. E. coli O157:H7 and E. coli O26:H11 represented 9.4 and 7.8% of cattle STEC isolates respectively, with other putative EHEC serotypes reported for the first time from cattle. Based on serotype and virulence factors, 20% of STEC were putative EHEC. Pulsed-field gel electrophoresis (PFGE) was used to compare the genomic profiles of STEC from dairy farms. Isolates common to cattle and the farm environment were identified. Multiple strains of STEC with high clonal turnover were detected in the faeces of cattle, and isolates appeared to be specific to individual farms. To fully assess the pre-slaughter EHEC risk factors on-farm, examination of STEC virulence is as important as determination of STEC prevalence.

Adhesins, Bacterial↗
PubMed2001

Pre-slaughter handling of cattle and Shiga toxin-producing Escherichia coli (STEC).

AIMS: The aim of the study was to monitor the shedding and transmission of generic and Shiga toxin-producing Escherichia coli (STEC) in a consignment of cattle during lot feeding. METHODS AND RESULTS: Faecal and environmental samples were tested for total E. coli and screened with PCR specific for Shiga toxin and O157 rfb. STEC were isolated using colony hybridization and characterized by serology and genotyping. STEC prevalence initially decreased after the diet shift from pasture to grain, although there were intermittent peaks in numbers of cattle shedding STEC and E. coli O157. Water troughs and soil were intermittently contaminated. Common genotypes and serotypes were isolated from animals, water and soil in the feedlot, with additional types introduced at slaughter. CONCLUSION: STEC and E. coli O157 are endemic in cattle and intermittent peaks in shedding occur. Prevention of these peaks and/or reduction in transmission is required to reduce the risk of carcass contamination during slaughter. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings contribute to the understanding of the ecology of STEC and suggest control points for reducing STEC contamination in feedlot cattle production.

Abattoirs↗
PubMed2001

Ancestral divergence, genome diversification, and phylogeographic variation in subpopulations of sorbitol-negative, beta-glucuronidase-negative enterohemorrhagic Escherichia coli O157.

The O157:H7 lineage of enterohemorrhagic Escherichia coli is a geographically disseminated complex of highly related genotypes that share common ancestry. The common clone that is found worldwide carries several markers of events in its evolution, including markers for acquisition of virulence genes and loss of physiological characteristics, such as sorbitol fermentation ability and beta-glucuronidase production. Populations of variants that are distinct with respect to motility and the sorbitol and beta-glucuronidase markers appear to have diverged at several points along the inferred evolutionary pathway. In addition to these variants, distinct subpopulations of the contemporary non-sorbitol-fermenting, beta-glucuronidase-negative O157:H7 clone were recently detected among bovine and human clinical isolates in the United States by using high-resolution genome comparison. In order to determine if these recently described subpopulations were derived from a regional or ancestral divergence event, we used octamer-based genome scanning, marker sorting, and DNA sequence analysis to examine their phylogenetic relationship to populations of non-sorbitol-fermenting, beta-glucuronidase negative O157:H7 and O157:H- strains from Australia. The inferred phylogeny is consistent with the hypothesis that subpopulations on each continent resulted from geographic spread of an ancestral divergence event and subsequent expansion of distinct subpopulations. Marker sorting and DNA sequence analyses identified sets of monophyletic markers consistent with the pattern of divergence and demonstrated that phylogeographic variation occurred through emergence of regional subclones and concentration of regional polymorphisms among distinct subpopulations. DNA sequence analysis of representative polyphyletic markers showed that genome diversity accrued through random drift and bacteriophage-mediated events.

Animals↗
PubMed2000

A longitudinal study of Shiga-toxigenic Escherichia coli (STEC) prevalence in three Australian diary herds.

Over a 12 month period, 588 cattle faecal samples and 147 farm environmental samples from three dairy farms in southeast Queensland were examined for the presence of Shiga-toxigenic Escherichia coli (STEC). Samples were screened for Shiga toxin gene (stx) using PCR. Samples positive for stx were filtered onto hydrophobic grid membrane filters and STEC identified and isolated using colony hybridisation with a stx-specific DNA probe. Serotyping was performed to identify serogroups commonly associated with human infection or enterohaemorrhagic Escherichia coli (EHEC). Shiga-toxigenic Escherichia coli were isolated from 16.7% of cattle faecal samples and 4.1% of environmental samples. Of cattle STEC isolates, 10.2% serotyped as E. coli O26:H11 and 11.2% serotyped as E. coli O157:H7, and the E. coli O26:H11 and E. coli O157:H7 prevalences in the cattle samples were 1.7 and 1.9%, respectively. Prevalences for STEC and EHEC in dairy cattle faeces were similar to those derived in surveys within the northern and southern hemispheres. Calves at weaning were identified as the cattle group most likely to be shedding STEC, E. coli O26 or E. coli O157. In concurrence with previous studies, it appears that cattle, and in particular 1-14-week-old weanling calves, are the primary reservoir for STEC and EHEC on the dairy farm.

Animals↗
PubMed1999

Shiga toxin-producing Escherichia coli in sheep and pre-slaughter lambs in eastern Australia.

Sheep and lambs from 14 farms in southern Queensland and one from central New South Wales were surveyed to determine the prevalence of Shiga toxin-producing Escherichia coli (STEC). STEC, isolated from 45% of 144 sheep faeces collected on the farms and 36% of 72 lamb faeces from abattoir yards, were tested for the presence of genes encoding virulence factors. Most (64%) of the 117 STEC isolates contained Shiga toxin 1 and 2 genes, 22% contained those encoding Shiga toxin 1, and 14% contained genes encoding Shiga toxin 2. The genes encoding the E. coli attaching and effacing factor were present in 2.6% of STEC and 26% contained the enterohaemolysin gene. The isolates that contained the E. coli attaching and effacing gene were serotype O157:H. This study has shown that STEC are widely distributed in eastern Australian sheep and lambs and are shed in their faeces prior to slaughter. Thus, there is potential for contamination of carcasses and entry of STEC into the human food chain.

Adhesins, Bacterial↗
PubMed1999

Dynamics of Shiga toxin-producing Escherichia coli (STEC) in feedlot cattle.

Feedlot cattle were monitored during fattening to determine changes in faecal shedding of Shiga toxin-producing Escherichia coli (STEC) and their relation to the coliform population. Faecal samples were enriched, screened for Shiga toxin genes (stx) by a polymerase chain reaction test and isolated using colony hybridization. During 117 d in the feedlot, there were differences in the numbers of coliforms shed and in the percentage of samples positive for stx. These fluctuations did not appear to be consistently related to changes in feed or time in the feedlot. The mean log coliform count for stx-positive samples (log 5.85 g-1) was similar to that for stx-negative samples (log 6.00 g-1). The STEC isolates obtained from the first 5 d in the feedlot belonged to eight serotypes. Later, one serotype (O136:H16) became the predominant STEC which appeared to be one clone as characterized by virulence determinants and pulsed-field gel electrophoresis.

Animal Feed↗
PubMed1992

Risk factors for the transmission of diarrhoea in children: a case-control study in rural Malaysia.

In response to a recorded increasing incidence of diarrhoea in Tumpat District, Malaysia, a case-control study was performed to identify modifiable risk factors for the transmission of diarrhoea, in children aged 4-59 months. Ninety-eight pairs of children, matched on age and sex, were recruited prospectively from health centres. Exposure status was determined during a home visit. Interviewers were 'blinded' as to the disease status of each child. Odds ratios were measured through matched pair analysis and conditional logistic regression. Risk factors for diarrhoea identified were: reported--drinking of unboiled water, storage of cooked food before consumption and bottle feeding; and observations--animals inside the house and absence of washing water in latrines. Water quality, source of drinking water, reported hand washing behaviour, indiscriminate defecation by children, cup use and the absence of a functional latrine were not associated with diarrhoea. Nonsignificant associations were found for: accessibility of washing water source, type of water storage container and use of fly covers for food.

Acute Disease↗
PubMed1980

Fulminating systemic infection caused by Vibrio cholerae species which does not agglutinate with 0-1 V. cholerae antiserum.

A case of fatal septicaemia caused by Vibrio cholerae which did not agglutinate with 0 group 1 V. cholerae antiserum is presented. The illness occurred in a 64-year-old Aboriginal woman from Aurukun Mission in Cape York. The organism was isolated from multiple blood cultures and urine during life, and froma a large hepatic abscess found post mortem. The pathogenicity and epidemiology of the organism is discussed.

Agglutination↗
PubMed1979

ICMSF methods studies. XII. Comparative study for the enumeration of Clostridium perfringens in feces.

As the second phase of an international comparative study for the enumeration of Clostridium perfringens, four methods were compared for "total" and spore counts of C. perfringens in fecal specimens: the SFP (Shahidi-Ferguson perfringens) agar (A), TSC (tryptose-sulfite-cycloserine) agar (B), SC (sulfite-cycloserine) agar (C), and neomycin blood agar (D) methods. In both the total and spore count procedures, the confirmed C. perfringens counts in method D were lower than in methods A, B, and C. Little differences among methods were found in the percentages of presumptive colonies confirmed as C. perfringens. The nonspecific counts in methods A and D were generally greater than in B and C, but nonspecific microorganisms did not interfere in the enumeration of C. perfringens spores by any of the four methods. In overall performance, methods B and C were superior to A and D. The mean C. perfringens spore count was only 0.17 log lower than the mean total count. Spore counts alone are, therefore, adequate in investigations of C. perfringens outbreaks.

Bacteriological Techniques↗
PubMedDate not supplied

An evaluation of the hydrogen sulphide water screening test and coliform counts for water quality assessment in rural Malaysia.

The H2S water screening test and the membrane filtration faecal coliform count were compared with Escherichia coli counts for water samples collected from household water sources and domestic drinking water in rural Malaysia. Water samples were taken from 151 wells, 44 taps supplying water from the treated municipal supply and 192 domestic stored water supplies. E. coli were detected in 20% of the samples (42% of wells, 7% of tap water and 6% of drinking water). Excellent correlation (Spearman's rank correlation rs = 0.93) was found between the faecal coliform and E. coli counts for all sample types. The H2S method was poorly correlated whether read at 18 or 30 h. False positive rates were highest for well water, and false negative rates were highest for both well and drinking water samples, with low E. coli counts. The faecal coliform test was an excellent predictor of the presence of E. coli in these water samples, while the H2S test was very inadequate.

Enterobacteriaceae↗