Continuous source outbreak of campylobacteriosis traced to chicken.

Poultry is a source of human campylobacteriosis, but a large continuous source outbreak, heretofore, has not been attributed to both a single source of poultry and single serotype of Campylobacter. Here we report an outbreak of C. jejuni affecting 6 catering college trainees and 13 patrons of a restaurant in southern England. An epidemiological investigation successfully tracked the outbreak source to the farm of origin. Frequency of occurrence of campylobacters and outbreak serotype distribution were determined in index cases, the local population, and local chicken suppliers. The source farm was investigated and the effect of interventions assessed. A single outbreak serotype of C. jejuni was isolated from trainee chefs, patrons, and chicken supplied to the college by Wholesaler A. The Campylobacter isolation rate for Wholesaler A was 89% (98% outbreak serotype), compared to 40% for non-Wholesaler A (10% outbreak serotype). The isolation rate for 14 months averaged 85% (99% outbreak serotype) in chickens grown on two farms (X and Y) supplying Wholesaler A, contributing approximately 40% to all local cases. In the research reported here, a specific strain and hygiene practice were found to be important for understanding transmission of Campylobacter from poultry to humans in this outbreak.

Microbial ecology of Campylobacter jejuni in a United Kingdom chicken supply chain: intermittent common source, vertical transmission, and amplification by flock propagation.

A study of Campylobacter jejuni on a broiler chicken farm between 1989 and 1994 gave an estimated isolation rate of 27% (3,304 of 12,233) from a 0.9% sample of 1.44 million broiler chickens from six to eight sheds over 32 consecutive rearing flocks comprising 251 broiler shed flocks. During the study, C. jejuni was found in 35.5% of the 251 shed flocks but only 9.2% (23 of 251) had Campylobacter isolates in successive flocks, with 9 of those 23 sheds having the same serotype between consecutive flocks, indicating a low level of transmission between flocks. Analysis of a systematic sample of 484 of 3,304 (14.6%) C. jejuni isolates showed that 85% were of 10 serotype complexes but 58% were of 3 serotype complexes, indicating a high degree of strain similarity throughout the entire study. The three commonest types were detected in 8 of 32 flocks during the 5-year study period, suggesting an intermittent common external Campylobacter source. This hypothesis was tested by a retrospective cohort analysis of C. jejuni rates and types by reference to hatchery supplier of the 1-day-old chicks. Isolation rates of C. jejuni and frequency distribution of types were determined in 6-week-old broiler chickens identified by the hatchery supplying the original chicks. The isolation rate of C. jejuni in broilers, supplied by hatchery A, was 17.6%, compared to 42.9% (P < 0.0001) for broilers reared from chicks supplied by hatchery B. In two instances, when both hatcheries were used to stock the same farm flock, Campylobacter isolates were found only in those sheds with chicks supplied by hatchery B. Thus, the frequency distribution of Campylobacter types for chickens supplied by the two hatcheries over the 5-year period showed marked dissimilarity. These findings suggest that the isolation rate and type of Campylobacter isolates in broiler chickens was associated with the hatchery supplying chicks. The lack of diversity of types and the intermittent high positivity of sheds is evidence for a common source of C. jejuni introduced by vertical transmission rather than contamination at the hatchery or during transportation.

Procurement of information systems effectively (POISE): using the new UK guidelines to purchase an integrated clinical laboratory system.

Open tendering for medical informatics systems in the UK has traditionally been lengthy and, therefore, expensive on resources for vendor and purchaser alike. Events in the United Kingdom (UK) and European Community (EC) have led to new Government guidance being published on procuring information systems for the public sector: Procurement of Information Systems Effectively (POISE). This innovative procurement process, launched in 1993, has the support of the Computing Services Association (CSA) and the Federation of the Electronics Industry (FEI). This paper gives an overview of these new UK guidelines on healthcare information system purchasing in the context of a recent procurement project with an NHS Trust Hospital. The aim of the project was to replace three aging, separate, and different laboratory computer systems with a new, integrated turnkey system offering all department modules, an Open modern computer environment, and on-line electronic links to key departmental systems, both within and external to the Trust by the end of 1994. The new system had to complement the Trust's strategy for providing a modern clinical laboratory service to the local population and meet a tight budget.

Constructing a database for low cost identification of gram negative rods in clinical laboratories.

A database was constructed for the routine identification of Enterobacteriaceae and Gram negative rods growing aerobically on MacConkey agar. The test methods were based primarily on multipoint inoculation technology. The final database was constructed from the laboratory results of 4989 clinical isolates and 66 reference strains and was extensively analysed and evaluated. The proposed scheme is rapid, reliable, and cheap.

A general-purpose system for characterizing medically important bacteria to genus level.

A computer program and accompanying data matrix have been prepared for bacteria of medical interest, to assist the assignment of an unidentified bacterium to the most likely genus. The results on a set of relatively simple tests are entered. The program prints the more likely genera, followed by a list of diagnostic tables in Cowan & Steel (1974) and Buchanan & Gibbons (1974). Where available, identification matrices for further computer-assisted study, are presented. This program may be of particular help in laboratories where a wide range of bacteria have to be identified.

A collaborative evaluation of a rapid automated bacterial identification system: the Autobac IDX.

A collaborative evaluation of the Autobac IDX, a rapid, semi-automated bacterial identification system, was performed in three independent laboratories in three European countries. The system utilises growth inhibition by a series of chemical compounds. Subsequent analysis of the resultant data by quadratic discriminant function automatically results in a bacterial identification. Three sets of 30 strains were examined repeatedly in each of the participating laboratories. The reproducibilities obtained ranged from 85.6% to 96.6%, with an overall average of 91.8%. The accuracy of the system was also determined by examining 1076 isolates from the three participating laboratories. An overall accuracy of 90.3% was calculated by comparing the Autobac result with a reference method. When the results were weighted to represent clinical frequency, the accuracy was 93.6%.

Construction of matrices for computer-assisted identification of aerobic Gram-positive cocci.

Two identification matrices for use with computerized probabilistic identification were constructed, based on 327 reference strains and 212 field isolates of Gram-positive, aerobic coccoid bacteria. The first, MICR1, was constructed for catalase-positive strains (Micrococcaceae); the second, STPC1, for catalase-negative strains (streptococci). The quality of the resultant data was assessed using statistical analysis, and the value of the identification statistic used was considered in the light of possible alternatives.

Characterisation of an epidemic strain of Klebsiella and its variants by computer analysis.

An outbreak of hospital-acquired klebsiella infection was investigated by means of six different typing schemes. Interpretation of the information generated by these schemes proved difficult and allowed only tentative conclusions to be reached concerning the origin of some strains. Consequently, the results were subjected to computer analysis by means of a numerical taxonomic programme adapted for the purpose. A dendrogram was constructed giving the percentage similarity between strains. It established the source of four atypical strains and showed that three of them were derived from the original clone. This form of numerical epidemiological analysis could have useful applications in the investigation of hospital-acquired infection.