Lead and mercury residues in kidney and liver of Canadian slaughter animals.
(1/1054)
Liver and kidney samples were collected from Canadian slaughter animals during the winter of 1973-1974. A total of 256 samples were analyzed for lead. Mean lead levels of 1.02 ppm in poultry liver, 1.04 ppm in bovine liver, 1.02 ppm in bovine kidney, 0.73 ppm in pork liver and 0.85 ppm in pork kidney were found. A total of 265 samples were analyzed for mercury. Mean mercury levels of 0.003 ppm in poultry liver, 0.007 ppm in bovine liver, 0.008 ppm in bovine kidney, 0.001 ppm in pork liver and 0.013 ppm in pork kidney were found. All levels detected were below the Canadian official tolerance of 2 ppm for lead and administrative tolerance of 0.5 ppm for mercury. (+info)
Complementary randomly amplified polymorphic DNA (RAPD) analysis patterns and primer sets to differentiate Mycoplasma gallisepticum strains.
(2/1054)
Randomly amplified polymorphic DNA (RAPD) analysis was used to differentiate 7 strains of Mycoplasma gallisepticum. Six commercially available primers or primer combinations were screened for their ability to differentiate vaccine and type strains. Although major and minor bands were produced with each primer, many of the primers were unsuitable for strain differentiation. The use of primer 6 and combined primers 3 and 4 resulted in complementary RAPD banding patterns for each M. gallisepticum strain. Eleven different isolates representing 7 different strains were segregated into 7 different patterns, corresponding to the 7 strains. (+info)
Cloning of Mycoplasma synoviae genes encoding specific antigens and their use as species-specific DNA probes.
(3/1054)
A genomic library of Mycoplasma synoviae (MS) was generated by using bacteriophage lambda gt11 as a cloning and expression vector. Identification of recombinant clones highly specific to MS was achieved by screening the library for expression of MS proteins with polyclonal antiserum that had been preadsorbed with 6 heterologous avian mycoplasma species antigens. Expression of the recombinant clones in Escherichia coli followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the total cell lysates and immunoblot yielded a predominant reactive fusion protein of 165 kD. Two clones (MS2/28 and MS2/12) that yielded inserts of different size were selected. The 2 MS DNA inserts were subcloned in a plasmid vector, labeled with digoxigenin, and used as probes for the specific recognition of several MS strains. A high degree of conservation was demonstrated for the MS2/12 and MS2/28 genes in tested MS strains. In addition, neither DNA fragment recognized any other avian mycoplasma species (M. gallisepticum, M. meleagridis, M. gallinarum, M. iners, M. anatis, and M. iowae), thus indicating their high specificity to MS. The sensitivity of the slot blot hybridization method using digoxigenin-labeled MS2/12 and MS2/28 probes for direct detection of MS from broth cultures of field isolates was 10(5) colony-forming units/ml. These results demonstrate the effectiveness of adsorbed antisera for the isolation of species-specific mycoplasma DNA and the potential for its use as probes for the specific and direct detection of MS from broth cultures of field isolates. (+info)
Phage type conversion in Salmonella enterica serotype Enteritidis caused by the introduction of a resistance plasmid of incompatibility group X (IncX).
(4/1054)
The plasmid pOG670, a 54 kb, conjugative plasmid that specifies resistance to ampicillin and kanamycin and belonging to the incompatibility group X (IncX), was transferred into 10 isolates of Salmonella enterica serotype Enteritidis belonging to 10 different phage types (PT1, 2, 3, 4, 8, 9, 9b, 10, 11 and 13). Acquisition of the plasmid by these strains did not result in the loss of any resident plasmids but resulted in phage type conversion in 8 of the 10 strains (PT1, 2, 4, 8, 9, 9b, 10 and 11). The observed changes in phage type were found to result from the loss of sensitivity to 3 of the 10 typing phages used (phages 3, 5 and 7). Where the conversion resulted in a change to a defined phage type, both the new and original PTs belonged to the same, previously described, evolutionary lines. Enteritidis PTs 1, 4 and 8, commonly associated with poultry world-wide, were converted to PTs 21, 6 and 13a respectively. The results indicate a different route for phage type conversion Enteritidis from others reported in the literature and, although IncX plasmids are not normally present in PT8 or PT13a, may suggest a possible mechanism/link connecting these phage types. (+info)
Molecular typing of Salmonella serotype Thompson strains isolated from human and animal sources.
(5/1054)
One-hundred-and-thirteen isolates of Salmonella serotype Thompson from diverse sources in seven countries were characterized by PvuII ribotyping and IS200 fingerprinting. Ten PvuII ribotypes were observed. The predominant PvuII ribotype 1 represented a major clone of world-wide distribution but was not found in Australia; PvuII ribotypes 2 and 3 represented minor clones. HincII ribotyping discriminated subtypes within PvuII ribotype 1: HincII ribotype 1 was distributed widely but HincII ribotype 2 was found mainly in Scottish isolates. None of 101 isolates of PvuII ribotypes 1-3 contained copies of IS200. All 12 isolates of PvuII ribotypes 4-10 were from Australia and 7 of them contained copies of IS200 of 5 different profiles. These results suggest the existence of at least two lineages of Salmonella Thompson with a different geographical distribution. The finding that most isolates from man and poultry in Scotland belonged to the same ribotype (PvuII 1/HincII 2) and were IS200-negative suggests that poultry is an important source of human infection in Scotland. (+info)
High-resolution genotyping of Campylobacter strains isolated from poultry and humans with amplified fragment length polymorphism fingerprinting.
(6/1054)
For epidemiological studies of Campylobacter infections, molecular typing methods that can differentiate campylobacters at the strain level are needed. In this study we used a recently developed genotyping method, amplified fragment length polymorphism (AFLP), which is based on selective amplification of restriction fragments of chromosomal DNA, for genetic typing of Campylobacter jejuni and Campylobacter coli strains derived from humans and poultry. We developed an automated AFLP fingerprinting method in which restriction endonucleases HindIII and HhaI were used in combination with one set of selective PCR primers. This method resulted in evenly distributed band patterns for amplified fragments ranging from 50 to 500 bp long. The discriminatory power of AFLP was assessed with a C. jejuni strain, an isogenic flagellin mutant, and distinct C. jejuni strains having known pulsed-field gel electrophoresis and fla PCR-restriction fragment length polymorphism genotypes. Unrelated C. jejuni strains produced heterogeneous patterns, whereas genetically related strains produced similar AFLP patterns. Twenty-five Campylobacter strains obtained from poultry farms in The Netherlands grouped in three C. jejuni clusters that were separate from a C. coli cluster. The band patterns of 10 C. jejuni strains isolated from humans were heterogeneous, and most of these strains grouped with poultry strains. Our results show that AFLP analysis can distinguish genetically unrelated strains from genetically related strains of Campylobacter species. However, desirable genetically related strains can be differentiated by using other genotyping methods. We concluded that automated AFLP analysis is an attractive tool which can be used as a primary method for subtyping large numbers of Campylobacter strains and is extremely useful for epidemiological investigations. (+info)
Salmonellosis in North Thames (East), UK: associated risk factors.
(7/1054)
We assessed the rate of salmonella infections and risk factors associated with infection in North East Thames in 1993. Cases of culture confirmed infection were identified through microbiology laboratories and environmental health officers in the North East Thames. A total of 1730 cases were reported and 209 of these individuals (those who could be contacted within a 3-week interval after onset of symptoms) and matched controls were interviewed by telephone. In addition randomly selected controls were interviewed over a 4-month period about recent gastric acid lowering medication and antimicrobial ingestion. Sixty-six serotypes were identified: S. enteritidis was isolated from 1179 (69%) cases, S. typhimurium from 221 (13%), S. virchow from 77 (4%) and S. newport 25 (1%). Infections were more frequent in summer months. Highest rates were documented in children under 2 years of age for S. enteritidis (108/100,000) and under 1 year for S. typhimurium (36/100,000). Using the Townsend score, highest isolation rates of S. enteritidis were in more prosperous areas (36/100,000 vs. 27/100,000; odds ratio (OR) 1.3, 95% confidence intervals (CIs) 1.2-1.6, P < 0.0001), while for S. typhimurium, there was no relation between deprivation index and isolation rates areas (6.4/100,000 vs. 6.1/100,000; OR 1.1, 95% CIs 0.8-1.5, P = 0.77). The case control study showed a significant association between ingestion of products containing raw eggs and S. enteritidis infection (8/111 cases vs. 0/110 controls; OR undefined, lower 95% CIs 3.4). Individuals with salmonella infection were significantly more likely to have travelled abroad in the week before the onset of illness [42/186 (23%) vs. 1/182 (0.5%); OR 40, 95% CIs = 5.5-291, P < 0.001] and to report gastroduodenal disease [11/143 (7%) vs. 3/143 (2%); OR 5.0, 95% CIs = 1.1-23, P = 0.04]. There was an association between illness and gastric acid-lowering medications [unmatched controls OR 22.3 (95% CIs 1.5-3.7, P = 0.0002), matched controls OR 3.7 (95% CIs 1.0-3.8, P = 0.07)], but no association with antimicrobial ingestion. (+info)
Case-control study of risk factors for avian influenza A (H5N1) disease, Hong Kong, 1997.
(8/1054)
In May 1997, a 3-year-old boy in Hong Kong died of a respiratory illness related to influenza A (H5N1) virus infection, the first known human case of disease from this virus. An additional 17 cases followed in November and December. A case-control study of 15 of these patients hospitalized for influenza A (H5N1) disease was conducted using controls matched by age, sex, and neighborhood to determine risk factors for disease. Exposure to live poultry (by visiting either a retail poultry stall or a market selling live poultry) in the week before illness began was significantly associated with H5N1 disease (64% of cases vs. 29% of controls, odds ratio, 4.5, P=.045). By contrast, travel, eating or preparing poultry products, recent exposure to persons with respiratory illness, including persons with known influenza A (H5N1) infection, were not associated with H5N1 disease. (+info)