Identifying the seasonal origins of human campylobacteriosis.

Human campylobacteriosis exhibits a distinctive seasonality in temperate regions. This paper aims to identify the origins of this seasonality. Clinical isolates [typed by multi-locus sequence typing (MLST)] and epidemiological data were collected from Scotland. Young rural children were found to have an increased burden of disease in the late spring due to strains of non-chicken origin (e.g. ruminant and wild bird strains from environmental sources). In contrast the adult population had an extended summer peak associated with chicken strains. Travel abroad and UK mainland travel were associated with up to 17% and 18% of cases, respectively. International strains were associated with chicken, had a higher diversity than indigenous strains and a different spectrum of MLST types representative of these countries. Integrating empirical epidemiology and molecular subtyping can successfully elucidate the seasonal components of human campylobacteriosis. The findings will enable public health officials to focus strategies to reduce the disease burden.

Environmental determinants of Ixodes ricinus ticks and the incidence of Borrelia burgdorferi sensu lato, the agent of Lyme borreliosis, in Scotland.

Lyme borreliosis (LB) is the most common arthropod-borne disease of humans in the Northern hemisphere. In Europe, the causative agent, Borrelia burgdorferi sensu lato complex, is principally vectored by Ixodes ricinus ticks. The aim of this study was to identify environmental factors influencing questing I. ricinus nymph abundance and B. burgdorferi s.l. infection in questing nymphs using a large-scale survey across Scotland. Ticks, host dung and vegetation were surveyed at 25 woodland sites, and climatic variables from a Geographical Information System (GIS) were extracted for each site. A total of 2397 10 m2 transect surveys were conducted and 13 250 I. ricinus nymphs counted. Questing nymphs were assayed for B. burgdorferi s.l. and the average infection prevalence was 5·6% (range 0·8-13·9%). More questing nymphs and higher incidence of B. burgdorferi s.l. infection were found in areas with higher deer abundance and in mixed/deciduous compared to coniferous forests, as well as weaker correlations with season, altitude, rainfall and ground vegetation. No correlation was found between nymph abundance and infection prevalence within the ranges encountered. An understanding of the environmental conditions associated with tick abundance and pathogen prevalence may be used to reduce risk of exposure and to predict future pathogen prevalence and distributions under environmental changes.

Combining risk assessment and epidemiological risk factors to elucidate the sources of human E. coli O157 infection.

E. coli O157 can be transmitted to humans by three primary (foodborne, environmental, waterborne) and one secondary (person-to-person transmission) pathways. A regression model and quantitative microbiological risk assessments (QMRAs) were applied to determine the relative importance of the primary transmission pathways in NE Scotland. Both approaches indicated that waterborne infection was the least important but it was unclear whether food or the environment was the main source of infection. The QMRAs over-predicted the number of cases by a factor of 30 and this could be because all E. coli O157 strains may not be equally infective and/or the level of infectivity in the dose-response model was too high. The efficacy of potential risk mitigation strategies to reduce human exposure to E. coli O157 using QMRAs was simulated. Risk mitigation strategies focusing on food and environment are likely to have the biggest impact on infection figures.

Putative household outbreaks of campylobacteriosis typically comprise single MLST genotypes.

During a 15-month period in Scotland a small but important number of human Campylobacter cases (3·2%) arose from 91 putative household outbreaks. Of the 26 outbreaks with known strain composition, 89% were composed of the same MLST which supports the potential use of MLST in public health epidemiology. The number of cases associated with household outbreaks is much larger than general outbreaks and there is some evidence to indicate that there may be secondary transmission, although this is relatively rare.

Multi-locus sequence types of Campylobacter carried by flies and slugs acquired from local ruminant faeces.

AIMS: To assess whether flies and slugs acquire strains of Campylobacter jejuni and Campylobacter coli present in local ruminant faeces. METHODS AND RESULTS: Campylobacter was cultured from flies, slugs and ruminant faeces that were collected from a single farm in Scotland over a 19-week period. The isolates were typed using multi-locus sequence typing (MLST) and compared with isolates from cattle and sheep faeces. Campylobacter jejuni and Camp. coli were isolated from 5·8% (n=155, average of 75 flies per pool) and 13·3% (n=15, average of 8·5 slugs per pool) of pooled fly and slug samples, respectively. The most common sequence type (ST) in flies was Camp. coli ST-962 (approx. 40%) regardless of the prevalence in local cattle (2·3%) or sheep (25·0%) faeces. Two positive slug pools generated the same ST that has not been reported elsewhere. CONCLUSIONS: Despite their low carriage rate, flies are able to acquire Campylobacter STs that are locally present, although the subset carried may be biased when compared to local source. Slugs were shown to carry a previously unreported Campylobacter ST. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has demonstrated that flies carry viable Campylobacter and may contribute to the transfer of STs within and between groups of animals on farms. Further, they may therefore present a risk to human health via their contact with ready-to-eat foods or surfaces.

Campylobacter immunity and coinfection following a large outbreak in a farming community.

An outbreak of campylobacteriosis affected approximately one-half of 165 people attending an annual farmers' dance in Montrose, Scotland, in November 2005. Epidemiological investigations, including a cohort study (n = 164), identified chicken liver paté as the most likely vehicle of infection. Paté preparation involved deliberate undercooking of chicken livers by flash-frying, followed by mechanical homogenization. Typing of 32 Campylobacter strains (isolated from submitted stools) by multilocus sequence typing identified four distinct clades of Campylobacter jejuni. There was good agreement when isolates were typed by Penner serotyping, pulsed-field gel electrophoresis, and flaA short variable region sequencing but poorer agreement with phage and antibiotic susceptibility testing. At least three attendees were coinfected with two Campylobacter strains each. The outbreak was probably due to several livers contributing Campylobacter strains that survived undercooking and were dispersed throughout the paté. The study highlights improper culinary procedures as a potential human health risk and provides a striking counterexample to the "dominant outbreak strain" view of point source outbreaks of food-borne infections. It also demonstrates that previous exposure to biologically plausible sources of Campylobacter may confer protection against subsequent infection.

Characterising transmission of a tuberculosis genotype in Scotland: a qualitative approach to social network enquiry.

SETTING: Contact investigation resulting from specimens sent to the Scottish Mycobacteria Reference Laboratory. OBJECTIVE: To characterise patients and types of exposures associated with transmission of a prevalent Mycobacterium tuberculosis genotype in Scotland. DESIGN: A combined approach using molecular epidemiology and semi-structured patient interviews for social network enquiry. RESULTS: We investigated social connections between 64 patients diagnosed between 1994 and 2004. Fifty-five per cent had > or = 1 identifiable contact. One third (n = 14, 32.6%) of the 43 epidemiological links detected were discerned as a result of patient interviews and were not previously recorded on surveillance reports, nor recognised by nurse specialists (all were non-household contacts). Sixteen putative sites of exposure were identified, 11 were public houses. Rather than a single-source outbreak, eight pockets of transmission were identified, the largest involving UK-born alcohol-misusing males frequenting several public houses. CONCLUSIONS: Using a standardised approach to explore themes around which individuals may have been exposed to TB resulted in the detection of previously unrecognised epidemiological links. Epidemiological data obtained from cluster investigations, e.g., risk and social behaviours that increase the risk of infection and sites of putative exposure, can enhance the development of more appropriate questions for the contact tracing interview.

Human fetal adrenal hydroxysteroid sulphotransferase: cDNA cloning, stable expression in V79 cells and functional characterisation of the expressed enzyme.

Dehydroepiandrosterone sulphate (DHEAS) is a major adrenal secretory product, particularly in the fetus where it serves as a substrate for oestrogen biosynthesis by the placenta. The enzyme in the adrenal responsible for synthesising DHEAS, hydroxysteroid sulphotransferase (HST), is therefore essential for human development. We have isolated a full-length cDNA clone, encoding human fetal adrenal HST, and constructed a stable cell line expressing it by transfection into V79 Chinese hamster lung fibroblast cells. This cDNA was essentially identical to that isolated from adult human liver, where the role of HST is less well understood. This recombinant cell line allowed determination of the substrate specificity and kinetic properties of this enzyme towards various steroid hormones, and by comparison of these activities with human liver cytosol we have shown that HST is the major sulphotransferase responsible for the sulphation of DHEA, androsterone and pregnenolone in man and that, functionally, the hepatic and adrenal enzymes are very similar. The expressed HST was also active with testosterone, cortisol (although at low levels) and the xenobiotic 17 alpha-ethinyloestradiol, but not with oestrone or 1-naphthol. We have therefore created a valuable resource for the study of this important enzyme.

The efficacy of the heat killing of Mycobacterium tuberculosis.

There is concern that current procedures for the heat inactivation of Mycobacterium tuberculosis may not be adequate. This raises serious safety issues for laboratory staff performing molecular investigations such as IS6110 restriction fragment length polymorphism typing. This paper confirms that the protocol of van Embden et al, as performed routinely in this laboratory, is safe and effective for the heat inactivation of M tuberculosis. This procedure involves complete immersion of a tube containing a suspension of one loopfull of growth in a water bath at 80 degrees C for 20 minutes. Seventy four isolates were included in this investigation. Despite prolonged incubation for 20 weeks, none of the heat killed M tuberculosis suspensions produced visible colonies or gave a positive growth signal from liquid culture. This method did not affect the integrity of the DNA for subsequent molecular investigations.

Molecular epidemiology of a large outbreak of multiresistant Klebsiella pneumoniae.

An outbreak of multiresistant Klebsiella pneumoniae has continued in the Grampian Region of Scotland since 1992. The organism, which generally produces an extended-spectrum beta-lactamase (ESBL), has spread to several hospitals and nursing homes. DNA from 80 possible outbreak isolates was digested with the restriction endonucleases XbaI and SpeI, and the patterns obtained by pulsed-field gel electrophoresis were compared. Restriction patterns of 79 of the isolates were found to be highly similar with both restriction enzymes, whereas one isolate was unrelated. The outbreak isolates were divided into six subtypes with SpeI and 16 subtypes with XbaI. These subtypes were independent of antibiotic susceptibility pattern, date of isolation and ward of origin, but the XbaI subtype did correlate with the SpeI subtype. It was concluded that the Klebsiella isolates of this outbreak were clonally related.

Molecular epidemiology and antibiotic resistance of Enterobacter spp. from three distinct populations in Grampian, UK.

The distribution of Enterobacter spp. within the population of Aberdeen Royal Infirmary was compared with the outpatient population with regard to molecular epidemiology and antibiotic resistance. Enterobacter spp. from 60 patients and one environmental site were characterised as ITU, non ITU and outpatients' isolates. Thirty-five percent were blood culture isolates. Cefotaxime resistant strains in the hospital were frequent. Cefotaxime (64%) sensitive isolates were inducible for hyperproduction of Bush group 1 beta-lactamase. Isolates were further investigated by PFGE. Isolates (27%) were clonally related and typed in four clusters. Consecutive isolates were studied in selected patients showing minor genomic changes. One environmental isolate from a deep sink at ITU was related to a patient's isolate.

Preparation and characterization of anti-peptide antibodies directed against human phenol and hydroxysteroid sulphotransferases.

Sulphotransferases (STs) catalyze the sulphation and, in general, detoxication of a large number of xenobiotics and endogenous compounds. A total of six synthetic peptides derived from the cDNA-derived amino acid sequences of the human phenol-sulphating form of phenosulphotransferase (P-PST) and human hydroxysteroid sulphotransferase (HST)--three from each sequence--were separately conjugated to the carrier protein keyhole limpet hemocyanin, and used to immunize rabbits. One successful antibody preparation was produced from among the P-PST peptides, and two from the HST peptides. On immunoblot analysis following SDS/PAGE, the anti-P-PST antibodies recognized two major forms of phenol ST in man, P-PST and the monoamine-sulphating form of PST, M-PST, and the two antibody preparations against HST recognized the human HST. These experiments demonstrate that it is possible to design specific antibodies against human sulphotransferases based on their amino acid sequences.

Salmonella septic arthritis: a case report and review.

We describe a case of septic arthritis in a child with no apparent predisposing conditions. Salmonella virchow was isolated from her knee and faeces, both isolates being identical except for the latter's resistance to ampicillin. Evidence is presented for the acquisition of ampicillin resistance in vivo, including the demonstration of the R plasmid and its ready transferability to Escherichia coli. The recent literature on the subject is reviewed and the role of group CI salmonellae in invasive disease is examined.

Voices of experience: making students the experts.

A poster campaign targeting 1st-year students was developed on the basis of responses of student focus groups to the following questions. 1. What are the major problems faced by incoming students regarding academic performance, alcohol use, relationships, attitudes toward their appearance and/or weight? 2. What are some of the ways in which you, or people you know, have coped with these problems effectively? An evaluation found that 89% of 1st-year students had read the posters and that 56% had used at least 1 of the tips. The campaign followed guidelines for promoting behavioral change suggested by the research of Prochaska on stages of change and Bento's social marketing model.

Source attribution, prevalence and enumeration of Campylobacter spp. from retail liver.

Campylobacter prevalence from retail liver (chicken, cattle, pig and sheep) was found to be 81%, 69%, 79% and 78% respectively. Molecular source attribution demonstrated that strains from chicken liver were most similar to those found commonly in humans. This provides further evidence of liver being a probable source of human infection.

Chromosomal mapping in Erwinia carotovora subsp. carotovora with the IncP plasmid R68::Mu.

Conjugational gene transfer was established in Erwinia carotovora subsp. carotovora SCRI193 by using plasmid R68::Mu c+ to mobilize the chromosome into multiply mutant recipients. It was observed that although the plasmid alone mobilized markers randomly at a frequency of ca. 10(-5) chromosomal recombinants per donor, the presence of a Mu prophage on the chromosome of the donor increased the frequency of mobilization of markers adjacent to the prophage by up to 10-fold. Using this system it was possible to order 17 chromosomal mutations. The behavior of Mu in E. carotovora subsp. carotovora was also studied.

A Mycobacterium tuberculosis IS6110 preferential locus (ipl) for insertion into the genome.

A 267-nucleotide Mycobacterium tuberculosis genomic sequence (ipl, the IS6110 preferential locus) which can harbor the insertion sequence IS6110 at six alternative locations has been identified in some three-quarters of the isolates tested. Only one IS6110 copy was observed at this locus in the ipl::IS6110(+)-containing isolates tested, and all insertions had the same orientation. The implications of this finding for IS6110 fingerprint typing methods is discussed in this work.

Molecular epidemiology of Mycobacterium malmoense infections in Scotland.

Clinical isolates of Mycobacterium malmoense collected over 5 years from patients across Scotland with a variety of diseases have been characterized by pulsed-field gel electrophoresis (PFGE), ribotyping, and 16S ribosomal DNA gene sequencing. Results indicate that this species harbors little genetic diversity and that the different strain types that were identified by PFGE showed no correlation with geographical origin or date of isolation.

Allelic variation in the Helicobacter pylori flagellin genes flaA and flaB: its consequences for strain typing schemes and population structure.

Extensive DNA sequence diversity was noted in Helicobacter pylori flagellin genes flaA and flaB. PCR amplified sequences from 49 isolates were digested with AluI, HindIII, MboI or MspI, the resultant patterns were compared between the different isolates and these used to differentiate the isolates from each other. Evidence that the extensive diversity that was found in these genes is the result of reassortment of sequences between strains in the bacterial population is presented, such that a comparatively small number of individual sequence mutations can recombine together in random combinations to form a greater number of distinct alleles. Geographical differences in the predominant patterns in the flaA alleles were also observed and could reflect regional differences either in the human host population or in the bacterial population. In view of the genetic complexity of this species, molecular typing schemes designed to identify related strains may falsely associate strains if the methods do not characterize sufficient genetic sites to exclude chance associations of genetic markers in strains which are actually not closely related to each other.