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Biomedical subjects

I G Wilson

Publications and source records attributed to I G Wilson.

At least 19 recordsLinked to original sources
PubMed2004

Antimicrobial resistance of Salmonella in raw retail chickens, imported chicken portions, and human clinical specimens.

Salmonella isolates from raw, chilled, retail chickens (n = 434) sampled between 1998 and 2000 were tested for resistance to 12 antibiotics. Of 23 salmonellas isolated, 30% were susceptible and 30% were resistant or intermediately resistant to one antibiotic, 26% to two, and 13% to four or more. One Salmonella Saint-Paul and two Salmonella Typhimurium isolates were resistant to more than four antibiotics. Highest resistance rates were sulfonamide (52%), streptomycin (26%), tetracycline (22%), and ampicillin (17%). Isolates (n = 27) from frozen chicken portions (n = 150) imported from Brazil and Thailand (generally for manufacturing and catering) were also tested. Brazilian salmonellas showed no multiple resistance, but an isolate of Salmonella Virchow from Thai chickens was resistant to two antibiotics. This compared with 39% resistance to two or more antibiotics in nonimported isolates. Resistance patterns of both sets of chicken isolates were compared with human fecal clinical isolates (n = 274) submitted for routine examination at this hospital, and a greater similarity was found between the clinical and local isolates than with imported salmonellas. Sulfonamide resistance in imported salmonellas was lower than that of nonimported and clinical isolates. Resistance to one or more antimicrobial was found in 70% of nonimported raw retail chickens, 52% of imported chicken breast fillets, and 84% of human fecal isolates. Multiple resistance (to four or more antibiotics) is a much more limited problem.

Animals↗
PubMed2003

Antibiotic resistance of Campylobacter in raw retail chickens and imported chicken portions.

Campylobacter isolates from raw retail chickens (n = 434) sampled between 1998 and 2000 were tested for resistance to 12 antibiotics. Among 208 campylobacters tested, more than 90% of isolates were susceptible to 4 out of 9 antibiotics (nalidixic acid, erythromycin, chloramphenicol and gentamicin). Most campylobacters were resistant to 3 antibiotics and multiple resistance was found in 4%. Ciprofloxacin resistance was 11%. Campylobacter contamination (28%) in imported chickens (n = 150) was almost half that found in local whole chickens (50%), but the resistance of imported isolates (n = 42) was similar to that of local campylobacters. Resistance in isolates from imported chicken breasts was generally more common, but to only 4 antibiotics. Resistance patterns of chicken isolates were compared to human clinical isolates (n = 494), and a greater similarity was found between the clinical and local isolates than with imported campylobacters. Lower chloramphenicol resistance was found in clinical Campylobacter isolates than in those from chicken sources.

Animals↗
PubMed2002

Vancomycin-resistant enterococci in shellfish, unchlorinated waters, and chicken.

Vancomycin-resistant enterococci (VRE) have been a cause of increasing concern chiefly regarding the infection of hospital patients. There is suspicion, but limited evidence, that food and environmental spread may be important. Biomonitoring by examination of bivalve shellfish was used to assess the occurrence of VRE entering the environment. Using pre-enrichment and Lewisham and Slanetz and Bartley agars, 2/125 (1.6%) of shellfish were found to contain enterococci resistant to high levels of vancomycin. Lewisham agar allows relatively rapid identification of VRE. In a second phase of the work using pre-enrichment and Slanetz and Bartley agar, 4/151 (2.7%) shellfish and 5/27 (18.5%) raw chickens contained VRE. Using filtration and pre-enrichment, no VRE were found in 54 unchlorinated water samples. The study shows that environmental prevalence of VRE is low, and that raw chickens are frequently contaminated.

Agar↗
PubMed2002

Salmonella and campylobacter contamination of raw retail chickens from different producers: a six year survey.

Between 1995 and 2000, a prospective survey was undertaken to investigate the levels of contamination of raw retail chickens (n = 1,127) with salmonella and campylobacter. The levels of contamination over the 6-year period were 11 % (95 % CI +/- 6.5%) for salmonella, and 57% (95% CI +/- 95%) for campylobacter. S. Bredeney (20%) and S. Enteritidis (18%) were the dominant serovars. Although salmonella contamination was higher than in an earlier survey we conducted (7%), since 1998 it has declined to 6%. Many S. Enteritidis isolates (43%) were associated with one large integrated poultry organization that appears to have successfully managed the contamination, and the serovar has not been isolated since 1998. Contamination ranged from 0 to 44% between different producers. There was no significant difference between producers contributing large and small numbers of samples, although some small producers had much poorer contamination rates than others. S. Bareilly, S. Bredeney, S. Enteritidis and S. Virchow showed associations with particular producers. Campylobacter contamination remains high. Contamination ranged from 47 to 81% between different producers. This study did not show a temporal association between contamination of chickens and human campylobacter infections, indicating that many cases of human campylobacteriosis, particularly during seasonal peaks, do not originate from chickens. Control measures that have reduced salmonella contamination have been largely ineffective against campylobacter and new interventions are needed. Most raw chickens are contaminated with these pathogens, and communicating the importance of minimizing this risk to caterers and the public is vital in reducing human infections.

Animals↗
PubMed2001

The occurrence of enteric pathogens and Aeromonas species in organic vegetables.

A range of commercially available organic vegetables (n = 86) was examined for the presence of Salmonella, Campylobacter, Escherichia coli, E. coli O 157. Listeria and Aeromonas spp., to provide information on the occurrence of such organisms in organic vegetables in Northern Ireland. The study was not designed to quantify such organisms or to compare occurrence with conventionally farmed vegetables. Standard enrichment techniques were used to isolate and identify enteric pathogens and Aeromonas species. No Salmonella, Campylobacter, E. coli. E. coli O 157, Listeria were found in any of the samples examined. Aeromonas species were isolated from 34% of the total number of organic vegetables examined. Many (64%) of the organic vegetables examined were "ready-to-eat" after minimal processing, i.e., washing. Aeromonas spp. was isolated from 41% of these vegetables. Aeromonas spp. was not recovered from certain vegetable types. The most commonly isolated species of Aeromonas was Aeromonas schubertii with 21.0% of all samples contaminated with this species; 5.8% of samples contained A. hydrophila, 5.8% A. trota, 3.5% A. caviae and 2.3% contained A. veronii biovar veronii. Although Aeromonas species are frequently detected in organic vegetables, the absence of accepted enteric pathogens was encouraging, and does not support the allegation of organic foods being of high risk due to the farming methods used.

Aeromonas↗
PubMed2000

On binocular alternation.

Diaz-Caneja (1928) made some prescient observations about binocular rivalry. Being in French, however, his paper remained largely unknown to the broader research community. His findings are similar to those reported very recently by contemporary researchers who had independently observed similar phenomena. Using concentric circles and parallel lines as stimuli, Diaz-Caneja presented half of each form to opposite eyes to provoke binocular rivalry. He observed periods in the ensuing binocular alternations in which rivalry occurred between the good Gestalt forms, despite the fact that they were distributed between the eyes. He proposed that each half of a good form generates synchronised oscillations in the visual system, and that this synchronisation enables the dichoptically viewed halves of the one form to be perceived as a whole.

Animals↗
PubMed1998

Salmonella in raw shell eggs in Northern Ireland: 1996-7.

The shells and contents of 2090 packs of six raw eggs from shops in Northern Ireland were examined for the presence of salmonella between April 1996 and October 1997. Nine isolates of salmonella were detected from separate packs of eggs (0.43%). One of the isolates was from egg contents (0.05%), where salmonella can proliferate to levels likely to cause human infection if the egg is inadequately cooked. Visible dirt and organic contamination were poor predictors of salmonella contamination since most contaminated eggs had apparently clean and uncracked shells. Contaminated eggs were more likely to have been sold from small shops than supermarkets. Sampling for uncommon pathogens is expensive, labour intensive, and yields many negative results. The small numbers of positive results make it particularly susceptible to variations between methods. It continues to be important to cook eggs thoroughly to eliminate the risk of salmonellosis since this survey suggests that over 10,000 boxes containing one or more contaminated eggs may be sold in Northern Ireland each year. Caterers should use pasteurised liquid egg. A system of branding to enable eggs to be traced to individual flocks would assist in the investigation of outbreaks.

Eggs↗
PubMed1997

Microbiological quality of ice in hospital and community.

A survey was undertaken in response to a report of a clinical infection which had been related to an ice-making machine on a hospital ward. A detailed study of the ice microflora of 27 ice-making machines was performed. In a subsequent survey, ice samples (N = 194) from establishments such as bars and hotels were examined for bacterial indicators of hygiene. Samples from hospital ice-making machines yielded low numbers of a wide range of potentially opportunistic micro-organisms, many of environmental rather than clinical origin. For ice sampled in the community, the total aerobic plate count (TAPC) at 37 degrees C for 95% of the samples was < 500 cfu/mL, and at 22 degrees C 75% had < 500 cfu/mL. Examination for coliforms showed that 69% of samples contained no coliforms, but 20% contained > 100 coliforms/100 mL. Escherichia coli was detected in three samples but in very low numbers. This report investigates the relevance of ice machines to the control of hospital infection, the hygiene of ice in the community, discusses the microbiological quality of ice and proposes possible guidelines.

Bacterial Infections↗
PubMed1997

The effect of ice-cream-scoop water on the hygiene of ice cream.

A survey of unopened ice cream, ice cream in use, and ice-cream-scoop water (n = 91) was conducted to determine the effect of scoop water hygiene on the microbiological quality of ice cream. An aerobic plate count around 10(6) c.f.u. ml-1 was the modal value for scoop waters. Unopened ice creams generally had counts around 10(3)-10(4) c.f.u. ml-1 and this increased by one order of magnitude when in use. Many scoop waters had low coliform counts, but almost half contained > 100 c.f.u. ml-1. E. coli was isolated in 18% of ice creams in use, and in 10% of unopened ice creams. S. aureus was not detected in any sample. Statistical analysis showed strong associations between indicator organisms and increased counts in ice cream in use. EC guidelines for indicator organisms in ice cream were exceeded by up to 56% of samples.

Aerobiosis↗
PubMed1996

Salmonella in retail poultry in Northern Ireland.

A prospective survey was carried out in Northern Ireland between February and August 1994 to assess the current levels of salmonella in retail chickens, and to determine whether contamination rates differed between chickens sold in supermarkets and by butchers. One hundred and forty chilled and frozen raw chickens were sampled from retail display and examined for the presence of salmonella using an approved method. Contamination was commoner in chickens that were chilled, sold from smaller premises, and reared or slaughtered outside Northern Ireland. Salmonella enteritidis phage type 4 was the most commonly isolated type. The contamination rate of about 7% is considerably lower than in Great Britain and this may partially explain the lower rate of human salmonella infections in Northern Ireland. This finding supports the recommendations made in the Advisory Committee on the Microbiological Standards of Food's report on poultry meat, since many of the improvements proposed are already in operation in areas of the Northern Ireland poultry industry.

Animals↗
PubMed1996

Occurrence of Listeria species in prepacked retail sandwiches.

A survey of 725 prepacked sandwiches was conducted examining for the presence on enrichment, and by plate count, of Listeria species. Sandwiches were found to contain Listeria sp. more frequently than their component foods. Chicken, beef and bacon fillings were associated with more frequent isolation. Salad also was associated with more frequent isolation, but the increase was not significant. On enrichment, over 15% of sandwiches contained Listeria species. L. innocua and L. monocytogenes were the only species isolated by plate count at numbers > or = 100 cfu/g (1.5% of total samples). Potentially hazardous levels of L. monocytogenes (defined as > or = 10(3) cfu/g) were found in two sandwiches examined (0.3%), indicating that although Total Viable Counts (TVCs) may often be high, the risk of listeriosis to vulnerable individuals from sandwiches is relatively low. It is important to distinguish the risk of consuming potentially hazardous levels of a pathogen in food from the risk of contracting illness as a result of such an event.

Eggs↗
PubMed1996

Presence of Salmonella spp. and Campylobacter spp. in shellfish.

Bivalve molluscs, (cockles, mussels, scallops and oysters) were examined according to EC shellfish bed classification regulations for faecal coliforms, Escherichia coli and salmonella, and for coliforms and campylobacter which are not specified by these regulations. Salmonella serotypes were detected in 8% of 433 molluscs. Seven salmonella isolations (2%) were made from category A beds, nominally suitable for immediate consumption according to E. coli counts. A higher percentage of salmonella isolates (6%) was detected in shellfish which require relaying or depuration prior to eating. In another survey, thermophilic Campylobacter spp. were found in 42% of 380 shellfish. These findings show bed classification on the basis of indicator organisms alone is not sufficient to assure the absence of bacterial, and no doubt viral, pathogens. Depuration and end product specifications which require the absence of salmonellae are an essential part of these regulations. Microbiologists may wish to consider whether tests for pathogens such as salmonella and campylobacter should be included when determining the suitability of shellfish for human consumption.

Campylobacter↗
PubMed1995

Occurrence of Listeria species in ready to eat foods.

Over 8000 ready to eat foods were examined for the presence of Listeria species. Overall, 5% of foods were found to contain these organisms. Higher occurrence was found in some foods such as chicken (11%) and fish (14%). Most of the Listeria species isolated were L. monocytogenes (49%) and L. innocua (36%) with lower numbers of other species. No seasonal pattern in the recovery of L. monocytogenes was found. Unsatisfactory or potentially hazardous levels of L. monocytogenes were found in 14 products (< 0.2%), mostly cooked meats. Undercooked chicken products appeared to present the greatest risk for the duration of this survey. The small number of samples which were potentially hazardous suggests that the risk to consumers is not high, and this is confirmed by the absence of clinical cases in the region during the period of study.

Bacteriological Techniques↗
PubMed1994

A non-isotopic DNA hybridisation assay for the identification of Staphylococcus aureus isolated from foods.

A digoxygenin-labelled total genomic DNA probe was used to identify Staphylococcus aureus. Isolation and identification of organisms was possible in less than 4 days. Identification alone could be completed in less than 2 days, compared with over 5 days for identification of isolates by multipoint inoculation. The probe showed excellent discrimination of S. aureus from other staphylococci and from a wide range of bacteria commonly associated with milk and meat. The effectiveness of this probe was tested against cultural isolation of staphylococci in milk using Baird-Parker agar followed by identification using multipoint inoculation and API Staph. The probe gave comparable results to the conventional methods and, for large sample numbers, offered lower cost and greater ease of use.

Animals↗
PubMed1994

Some factors inhibiting amplification of the Staphylococcus aureus enterotoxin C1 gene (sec+) by PCR.

PCR amplification of the sec+ gene for staphylococcal enterotoxin C1 (SEC1) can be achieved from as little as 10 fg total genomic DNA (equivalent to less than 10 cells) using two nested primer pairs. The presence of bacterial cells, particularly thermonuclease-producing staphylococci, and the thermonuclease enzyme (TNase) itself, were found to be factors which individually and together reduced the sensitivity of PCR amplification.

DNA, Bacterial↗