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Biomedical subjects

F J Bolton

Publications and source records attributed to F J Bolton.

At least 37 records · Page 2Linked to original sources
PubMed2001

General outbreaks of infectious intestinal disease associated with fish and shellfish, England and Wales, 1992-1999.

Between 1992 and 1999 1425 foodborne general outbreaks of Infectious Intestinal Disease (IID) were reported to the PHLS Communicable Disease Surveillance Centre. Of these, 148 (10%) were associated with the consumption of fish and shellfish. Three main aetiologies were identified. Outbreaks associated with fish (47%) occurred more frequently in the summer months, and were linked with Scombrotoxic fish poisoning caused by the consumption of tuna that was improperly stored. Outbreaks associated with molluscs (36%) were associated with the consumption of oysters contaminated with viral pathogens, particularly in February. Outbreaks associated with the consumption of crustaceans (11%) often involved eating prawns that contained either salmonellas or viral pathogens. The maintenance of microbial quality from prior to capture/harvesting until the moment of consumption, based on a Hazard Analysis and Critical Control Point style approach, is essential if gastrointestinal illness associated with such produce is to be avoided.

Adolescent↗
PubMed2000

Waterborne Escherichia coli O157.

The waterborne route of Vero cytotoxin-producing E. coli (VTEC) O157 infection was first suggested in two unconnected human cases in 1985. Since then, waterborne VTEC O157 has been identified in sporadic cases and in outbreaks of illness. Recreational waters, private and municipal supplies have been implicated from microbiological, environmental and epidemiological studies of cases. In addition, a research cohort study of farm workers identified exposure to private water supplies as a risk factor for having antibodies to E. coli O157. Sources of contamination are thought to be animal and human faeces or sewage. The presence of low numbers of target organisms in water makes microbiological confirmation difficult, therefore epidemiological evidence has been essential in outbreak investigations. Despite the potential for contamination of water with VTEC O157, waterborne infection is relatively rare largely due to the susceptibility of the organism to water treatment processes. This paper presents the evidence for waterborne VTEC O157 infection, considering current microbiological, environmental and particularly epidemiological information.

Animals↗
PubMed2000

Campylobacter contamination of raw meat and poultry at retail sale: identification of multiple types and comparison with isolates from human infection.

Campylobacter species are the major cause of acute bacterial enteritis reported in the United Kingdom, nonetheless many aspects of campylobacteriosis epidemiology remain poorly understood. The aim of this study was to determine the prevalence of Campylobacter jejuni and Campylobacter coli in fresh bovine, ovine, and porcine liver and chicken portions from retail outlets and compare strain subtype distributions with those associated with cases of human campylobacteriosis occurring within the same period and study area. Meat samples were examined by both enrichment culture and direct plating, and Campylobacter isolates were subjected to the same test procedures (identification, serotyping, phagetyping, resistotyping) applied to the clinical strains. Campylobacter species were isolated from 73.2% of 489 samples examined. Chicken exhibited the highest contamination rate (83.3%), followed by lamb (72.9%), pig (71.7%), and ox (54.2%) liver. C. jejuni predominated in chicken (77.3%), lamb (75.0%), and ox (49.0%) liver, and C. coli predominated in pigs' liver (42.4%). Campylobacter fetus was identified in 12.5% of ox liver samples and also in pig and lamb. Of the human isolates, 89.3% were C. jejuni and 10.7% C. coli. The greatest variation in C. jeuni subtypes was observed among the chicken isolates (57 sero/phage-types), followed by human (48 types) and lamb (30 types). A significant proportion of the chicken and lamb isolates shared identical subtypes with the human strains, indicative of their role as potential sources of infection. Almost 30% of samples yielded multiple strains of Campylobacter, a finding that reinforces the epidemiological importance of selecting and testing more than one presumptive isolate per sample.

Animals↗
PubMed2000

Guidelines for the microbiological quality of some ready-to-eat foods sampled at the point of sale. PHLS Advisory Committee for Food and Dairy Products.

These guidelines for the microbiological quality of ready-to-eat foods represent a revision and expansion of guidelines first published by the PHLS in September 1992 and revised in March 1996. The latest guidelines incorporate many of the constructive comments received from food examiners and other microbiologists within and outside the PHLS and from environmental health officers throughout the United Kingdom. This document reviews the changes and the reasons they were made and sets out the new guidelines. It also clarifies the role of food examiners in interpreting the microbiological results of formal samples.

Colony Count, Microbial↗
PubMed1999

Presence of Campylobacter and Salmonella in sand from bathing beaches.

The purpose of this study was to determine the presence of thermophilic Campylobacter spp. and Salmonella spp. in sand from non-EEC standard and EEC standard designated beaches in different locations in the UK and to assess if potentially pathogenic strains were present. Campylobacter spp. were detected in 82/182 (45%) of sand samples and Salmonella spp. in 10/182 (6%). Campylobacter spp. were isolated from 46/92 (50%) of samples from non-EEC standard beaches and 36/90 (40%) from EEC standard beaches. The prevalence of Campylobacter spp. was greater in wet sand from both types of beaches but, surprisingly, more than 30% of samples from dry sand also contained these organisms. The major pathogenic species C. jejuni and C. coli were more prevalent in sand from non-EEC standard beaches. In contrast, C. lari and urease positive thermophilic campylobacters, which are associated with seagulls and other migratory birds, were more prevalent in sand from EEC standard beaches. Campylobacter isolates were further characterized by biotyping and serotyping, which confirmed that strains known to be of types associated with human infections were frequently found in sand on bathing beaches.

Bathing Beaches↗
PubMed1998

Quality assurance in food microbiology--a novel approach.

The introduction of quality systems as a requirement of laboratory accreditation is causing microbiologists to review current practices. The need for Quality Assurance (QA) in food microbiology is of growing importance and this paper presents a novel approach to implementing QA based on a system which is analogous to the Hazard Analysis Critical Control Point approach adopted by the food industry. The basis of the QA system is the recognition of Quality Assessment Points (QAPs). Several Quality Control and monitoring practices are suggested for each of the QAPs with the overall aim of developing a Total Quality Assurance system for food microbiology laboratories.

Animals↗
PubMed1998

Strategies in the development of media for the detection of food-borne pathogens.

Successful medium development is dependent on using a systematic approach and also by giving due consideration to the factors which can influence the performance of the medium at the various stages of assessment. The most important factors to be considered are: (i) the properties of the target organisms, (ii) the selection of test strains, (iii) the methods of evaluation, (iv) the basal medium and growth supplements, (v) the properties of the medium, and (vi) the intended use of the medium. If these are investigated fully then culture media can be optimised to fulfil the demands of modem microbiology techniques used for detection and confirmation of bacteria.

Culture Media↗
PubMed1998

A reverse transcriptase polymerase chain reaction assay for the detection of thermophilic Campylobacter spp.

A novel method was developed for the detection of thermophilic enteropathogenic campylobacters based on the detection of mRNA using the reverse transcriptase polymerase chain reaction (RT-PCR). The RNA extraction method, DNase treatment and RT-PCR assay were shown to be specific for mRNA. The assay is specific for the thermophilic campylobacters Campylobacter jejuni, Campylobacter coli and Campylobacter upsaliensis and restriction fragment length polymorphism (RFLP) analysis of the 256 bp amplified product with the restriction endonucleases Alu I, Dde I and Dra I revealed distinct species specific patterns. The assay was applied to the detection of C. jejuni cells killed by heating at 72 degreesC for 5 min and mRNA was detected by RT-PCR immediately after heat killing but became undetectable within 4 h when the cells were held at 37 degreesC. The assay therefore can differentiate between viable and dead cells of C. jejuni.

Campylobacter↗
PubMed1998

A comparison of the bactericidal and photobactericidal activities of aminoacridines and bis(aminoacridines).

An attempt was made to increase the activity of some antibacterial acridines in two ways: (a) via the use of bis-aminacrines (analogues of 1,6-bis-[9-acridinamino]hexane), in order to increase the potential for DNA intercalation and (b) via photoactivation, as several acridines are known to produce the cytotoxin singlet oxygen on irradiation. The bactericidal activity of the simple aminoacridines was much higher than that of the corresponding bis-acridine compounds. In addition, on low-power illumination of the compounds in liquid culture, many of the monomeric compounds exhibited marked increases in activity against both Gram-negative and Gram-positive bacteria, whereas the bis-acridines showed little or no increase.

Aminoacridines↗
PubMed1998

Characterisation of 16 Campylobacter jejuni and C. coli typing bacteriophages.

Taxonomic classification of bacteriophages specific for Campylobacter jejuni and C. coli has not been reported previously. A set of 16 virulent phages, distinguishable by their lytic spectra, has been used extensively for epidemiological typing of C. jejuni and C. coli at Preston Public Health Laboratory. These phages were investigated by electron microscopy, pulsed-field gel electrophoresis and restriction endonuclease analysis. All phages had icosahedral heads and long contractile tails. Accordingly, they were classified as members of the Myoviridae family. These phages could be subdivided into three groups according to genome size and head diameter: group I, two phages with head diameters of 140.6 and 143.8 nm and genome sizes of 320 kb; group II, five phages with average head diameters of 99 nm and average genome sizes of 184 kb; and group III, nine phages with average head sizes of 100 nm and average genome sizes of 138 kb. Phages NCTC12676 and NCTC12677 of group I had unusually large genomes of c. 320 kb which are two of the largest phage genomes to be described. Restriction endonuclease analysis demonstrated that DNA from the 16 phages was refractory to digestion by a number of restriction enzymes.

Bacteriophage Typing↗
PubMed1998

Verocytotoxin-producing Escherichia coli O157: public health and microbiological significance.

Escherichia coli O157 was recognised as a human pathogen in the late 1970s, its public health significance being recognised in 1982 when it was implicated in a large outbreak of infection associated with a fast-food restaurant in North America. Incidence of infection in the population is relatively low compared to other enteric pathogens; however, this organism causes a spectrum of disease increasing in severity from a mild diarrhoeal illness to haemorrhagic colitis, haemolytic uraemic syndrome (HUS) and, in some cases, death. Production of verocytotoxin and intimin, and the presence of a 60 mDa plasmid are thought to be important virulence factors; however, many currently unidentified factors may also contribute. The infectious dose of this organism is low and reports of food-borne, water-borne and person-to-person transmission have occurred, including several laboratory-acquired infections. Techniques for isolation, identification and confirmation of these organisms, based on cultural, immunological and molecular detection, are described. Additionally, schemes have been developed to type these organisms for epidemiological investigation, and the roles of phage typing and genotyping are discussed. These enable identification of sources and the introduction of intervention strategies for prevention of spread in the community.

Bacterial Toxins↗
PubMed1997

A community outbreak of Vero cytotoxin producing Escherichia coli O157 infection linked to a small farm dairy.

A community outbreak of infection with Vero cytotoxin producing Escherichia coli O157 (VTEC 0157) occurred in a small area of north west England in 1996. An outbreak control team was established to investigate the outbreak and implement control measures. Nine people developed symptomatic infections with VTEC O157, and a further three were found to be excreting the bacteria. All were infected with the same genotype of VTEC O157. Three children under 5 years of age and one adult were admitted to hospital. One child developed haemolytic uraemic syndrome. All cases recovered. All primary cases had consumed milk from a particular farm dairy. No other common foods were identified. The farm dairy had a faulty pasteuriser and the potential for post pasteurisation contamination existed. VTEC O157 was isolated from a milk sock specimen and from two cows, but these strains differed from that infecting the cases. All local doctors and the public were alerted and advised about preventative measures. Distribution of unpasteurised milk from the farm was discontinued as was the sale of pasteurised milk when the faulty pasteuriser was discovered. A replacement pasteuriser was installed and checked before milk was released for human consumption. No conclusive evidence of the origin of this outbreak was found, but the farm was the most probable source. The investigations raised concerns about the distribution of VTEC O157 colonised dairy cattle, the natural history of such colonisation, the effectiveness of pasteurisation with respect to the elimination of VTEC O157, and the effectiveness of current legislation for the prevention and control of milkborne infection.

Adult↗
PubMed1997

Comparison of a novel microaerobic system with three other gas-generating systems for the recovery of Campylobacter species from human faecal samples.

Three commercial gas-generating systems--CampyGen (Oxoid, UK), Oxoid BR56 (Oxoid, UK), and CampyPak Plus (Becton Dickinson, USA)--and the evacuation replacement technique were compared for the recovery of Campylobacter spp. from 500 human faecal samples collected from patients with gastroenteritis. Four hundred fifty faecal samples were tested upon receipt in the laboratory. Fifty faecal samples that had been previously found to be positive for Campylobacter spp. were tested retrospectively; these had been stored at 4 degrees C for more than 48 h. A total of 41 (9.1%) of the fresh faecal samples and 41 of 50 (82%) of the stored faecal samples were positive for thermophilic campylobacters. The CampyGen, the Oxoid BR56, the CampyPak Plus, and the evacuation replacement system detected Campylobacter spp. in 40 (97.6%), 39 (95.1%), 41 (100%), and 41 (100%) of the positive fresh faecal samples and in 37 (90.2%), 40 (97.6%), 39 (95.1%), and 40 (97.6%) of the stored samples, respectively. There was no statistical difference in performance of any of the four gas systems used (p = 0.98; chi-square test). Eighty-six percent of the isolates were Campylobacter jejuni and 14% were Campylobacter coli. Biotyping and phage typing of the isolates demonstrated that they were of a diverse range of subtypes. This study demonstrates that thermophilic campylobacters can be isolated from human diarrhoeal faecal samples using any of the four microaerobic-atmosphere-generating systems.

Campylobacter↗
PubMed1997

New media for detection and counting of Clostridia in foods.

The growth of pure cultures of Clostridium perfringens (ATCC 12922) and Cl. sporogenes (PA 3679) in five non-selective media, fluid thioglycollate medium (FTM), rapid perfringens medium (RPM), Columbia broth Malthus (CBM), reinforced clostridial medium (RCM) and lactose sulphite (LS), was monitored using conductance measurements with a Malthus analyser. Only FTM and CBM gave useful results. The correlation of log10 plate counts on blood agar of the pure strain of Cl. sporogenes with detection times in FTM was highly significant (r = 0.96, n = 73), and with detection times in CBM less so (r = -0.909, n = 33). The correlation of log10 counts on tryptose sulphite neomycin medium (TSN) of wild strains of Cl. sporogenes and Cl. perfringens with detection times with FTM in meat was also highly significant (r = 0.933, n = 54).

Bacteriological Techniques↗
PubMed1997

In-vitro photobactericidal activity of aminoacridines.

The toxicities of several aminoacridines were measured against pathogenic strains of both Gram-positive (Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) organisms. In several cases, illumination at a light dose of 6.3 J/cm2 resulted in considerable decreases in the minimum lethal drug concentrations required, giving up to 50-fold increases in bactericidal activity. Derivatives of 9-aminoacridine (aminacrine) exhibited phototoxicity against one or more of the test organisms, but the established photosensitizing acridines proflavine and acridine orange were photobactericidal against all strains.

Aminoacridines↗
PubMed1997

A study of photobactericidal activity in the phenothiazinium series.

The photodynamic antibacterial properties of a closely related series of commercially available phenothiazinium dyes were tested against a range of pathogenic strains of Gram-positive (Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus) and Gram-negative organisms (Escherichia coli, Pseudomonas aeruginosa). The photosensitisers were illuminated using a non-laser light source at a fluence of 1.75 mW cm-2 and this resulted in the enhancement of antibacterial activity in liquid culture. In several cases, illumination resulted in considerable decreases in the minimum lethal concentrations required, giving up to 100-fold increases in bactericidal activity.

Acridine Orange↗
PubMed1996

PHLS begins a national case control study of Escherichia coli O157 infection in England.

Infection with Vero cytotoxin producing Escherichia coli O157 (VTEC O157) is a growing public health problem and the commonest cause of acute renal failure in children in the United Kingdom. Foodborne outbreaks of VTEC O157 infection have been reported in the United Kingdom, other European countries, and North America. Most cases of infection are sporadic, however, and the contribution of food vehicles, animal contact, and person to person spread in the acquisition of infection needs to be clarified. The PHLS is starting a case control study in England to identify and estimate the relative importance of risk factors for the acquisition of VTEC O157 infection. The study will run for 12 months. This article describes its objectives and asks microbiologists, public health physicians, clinicians, and others who may be asked for details about cases or to find suitable controls for their help in achieving a successful outcome.

Case-Control Studies↗