Multiplex PCR amplification of invA and virA genes was developed enabling simultaneous detection in mussels of Salmonella spp. and Shigella spp., respectively. Simultaneous amplification of products of 215 and 275 bp was obtained either by using mixtures of individual strains of Sh. dysenteriae and Salm. typhimurium or spiked contaminated mussels with both bacteria. In the case of the mussels, 10–100 cells of Salmonella spp. and Shigella per millilitre of homogenate were detected by the multiplex PCR following a pre‐enrichment step to increase sensitivity and to ensure that detection was based on the presence of cultivable bacteria. Also, the sensitivity and specificity of this method was evaluated. Multiplex PCR amplification was shown to be an effective, sensitive and rapid method for the simultaneous detection of pathogens in mussels.

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In this study the assessment of randomly amplified polymorphic DNA (RAPD) analysis was established as a molecular epidemiological tool. RAPD analysis was performed to differentiate faecal Escherichia coli isolates from human and animal sources. E. coli strains (128) were isolated from human and animal faeces (from cattle and sheep). Genomic DNA was extracted and randomly amplified polymorphic DNA-PCR (RAPD-PCR) fingerprinting was performed. Seven arbitrary primers were tested with a view to discriminating between E. coli isolates from humans and E. coli isolates from animals. RAPD profiles were analysed with hierarchical cluster analysis using an unweighted pair group method. RAPD profiles obtained with three of the tested primers (1247, 1290 and 1254) established a distinct differentiation between E. coli isolates from humans and E. coli from animals. Low levels of misclassification and high levels of specificity make RAPD a sensitive, efficient and reliable means of distinguishing closely related strains.

BackgroundOn the 20th September 2005, soldiers and staff at the Air Force base in Western Greece experienced an outbreak of acute gastroenteritis. The purpose of this study was to identify the agent and the source of the outbreak in order to develop control measures and to avoid similar outbreaks in the future.MethodsA case-control analytical approach was employed with 100 randomly selected cases and 66 controls. Patients completed standardized questionnaires, odds ratios were calculated and statistical significance was determined using χ2 test.In addition, to identify the source of the infection, we performed bacteriological examination of food samples (included raw beef, cooked minced meat, grated cheese and grated cheese in sealed package) collected from the cuisine of the military unit.ResultsMore than 600 out of the 1,050 individuals who ate lunch that day, became ill. The overall attack rate, as the military doctor of the unit estimated it, was at least 60%. The overall odds ratio of gastroenteritis among those who had lunch was 370 (95% CI: 48–7700) as compared to those who didn't eat lunch. Among the symptoms the most prominent were watery diarrhoea (96%) and abdominal pain (73%). The mean incubation period was 9 h and the median duration of the symptoms was 21 h. In the bacteriological examination, Staphylococcus aureus was detected in a sample of raw beef (2,000 cfu per g) and in two samples of grated cheese; leftover cheese from lunch (7,800 cfu per g) and an unopened package purchased from the market (3,000 cfu per g).ConclusionThe findings of this study suggest that the aetiological agent of this outbreak was S. aureus. The food vehicle was the grated cheese, which was mixed with the beef and served for lunch in the military unit. This outbreak highlights the capacity of enterotoxin-producing bacteria to cause short term, moderately-severe illness in a young and healthy population. It underscores the need for proper food handling practices and reinforces the public health importance of timely notification of such outbreaks.

Aims:  Multiple antibiotic resistance (MAR) was performed on 128 Escherichia coli isolates, recovered from faecal samples of humans and animals (cattle, goat, sheep) to determine and compare their antibiotic resistance patterns and to evaluate them statistically in order to specify the source of the faecal material. Methods and Results:  Disk diffusion method was applied with a selection of antibiotics. Statistical approach was performed with hierarchical cluster analysis (CA), discriminant analysis (DA) and principal component analysis. Comparing human and animal isolates there was significant difference in levels of resistance to all antibiotics tested (P < 0·05) with 46 and 24 distinct resistance patterns for human and animal isolates respectively. CA and DA separated human and animal isolates with a high average rate of correct classification (99·2%), when all animal isolates were pooled together. Conclusions:  MAR analysis compared with appropriate statistical evaluation may provide a useful tool for differentiating the human or animal origin of E. coli isolates derived from environmental samples. Subsequently, determination of the source of faecal pollution becomes possible. Significance and Impact of the Study:  Determining the source of faecal pollution enables the prediction of possible risk for public health and the application of appropriate management plans for prevention of further contamination.