Scombrotoxic fish poisoning (SFP) is associated with the consumption of contaminated fish of the Scombroid family (including tuna, mackerel, herring, marlin, bonito and jacks). SFP is a chemical intoxication and symptoms occur within 10 minute to 2 h after consumption of preformed histamine in scombroid fish and include rash on the face, neck and upper chest, flushing, sweating, nausea, vomiting, diarrhoea, abdominal cramps, headache, dizziness, palpitations, oral burning sensation, metallic taste and hypotension. Symptoms usually resolve within 24 h. Although most cases do not seek medical attention, in some instances symptoms may be of sufficient severity to prompt cases to seek urgent medical attention, where antihistamine drugs may be used. Scombroid fish naturally contain high levels of histidine which is converted to toxic histamine as a result of histidine decarboxylase-producing bacteria if storage conditions are inadequate to control bacterial growth (Fig. 1). Histamine is heat stable and survives subsequent processing, including canning, and ingestion of fish with histamine at levels in excess of 1000 ppm (100 mg/100 g) can result in illness. Bacterial spoilage and production of histamine may occur at any stage in the food chain (i.e. from landing the fish, at the processing plant or in the distribution system or in catering premises or homes) and adequate temperature control is key in preventing bacterial growth and histamine formation. For control of fish belonging to the scombroid family the permissible level set by EU legislation for each batch of fish is an average histamine concentration lower than 100 ppm (10 mg/100 g).1 Surveillance of SFP is based on results from samples submitted to the Health Protection Agency Centre for Infections (Food Safety Microbiology Laboratory). However, this data may represent an under-ascertainment because investigations may take place through other laboratories such as public analysts. However, between 1992 and 2004, 56 outbreaks of SFP were reported to the Health Protection Agency from cases in England and Wales (0–10 incidents per year) affecting 296 people (Table 1). Analysis of outbreaks associated with fish and shellfish between 1992 and 1999 identified that SFP accounted for 32 per cent of these and that SFP outbreaks occurred more frequently during the summer months.2 Examples of incidents involving spoilage at the point of manufacture in a tuna factory in Sri Lanka and at the point of production in a sandwich bar in London are summarized in Table 2. There has been a recent increase in the number of outbreaks reported. Between December, 2004, and August, 2005, 24 SFP outbreaks and incidents (46 ill, 3 hospitalized) were reported to the HPA from several regions within England and Wales. Sixteen of the outbreaks occurred between December to June and the remaining eight occurred during the summer months up to August. A seasonal increase during the summer has been observed previously; however, the increase seen in the winter and spring months was unusual since outbreaks are more likely to occur during warmer weather after consumption of fish that has been improperly stored, handled and prepared.2 The outbreaks were associated with 21 catering premises (sandwich shops, restaurants, hotels and public houses) and three domestic setting, of which 23 were caused by consumption of tuna. Six of the catering premises were supplied with tuna from the same supplier in sealed foil vacuum packs that had low levels of histamine ( 3000 ppm). This suggests poor food handling and inadequate refrigeration during storage at these premises after the tuna packs were opened. In one of the other outbreaks, toxic histamine levels (>1970 ppm) were present in both sealed packs of raw and cooked tuna indicative of poor temperature control at some stage post-harvest, storage or transportation. Maintenance of microbiological quality from postharvest until the moment of consumption is essential if SFP associated with fish is to be avoided. The EU General Food Law Regulation 178/2002 requires the removal of contaminated food from the marketplace together with efficient and complete trace-back of incriminated food to the point of origin. The EU legal limits for histamine in food is <100 ppm, and following the recent SFP outbreaks, the Food Standards Agency has circulated a letter to food enforcement authorities to make them aware of the issue and emphasized the importance of following strict hygiene during
The accurate segregation of homologous chromosomes during the Meiosis I reductional division in most sexually reproducing eukaryotes requires crossing over between homologs. In baker's yeast approximately 80 percent of meiotic crossovers result from Mlh1-Mlh3 and Exo1 acting to resolve double-Holliday junction (dHJ) intermediates in a biased manner. Little is known about how Mlh1-Mlh3 is recruited to recombination intermediates and whether it interacts with other meiotic factors prior to its role in crossover resolution. We performed a haploinsufficiency screen in baker's yeast to identify novel genetic interactors with Mlh1-Mlh3 using sensitized
A simple amplified fragment length polymorphism method was developed for the epidemiological typing of Bacillus cereus. The method was applied to 21 cultures from seven food poisoning and eight non-food poisoning incidents. Results were compared with those obtained by conventional serotyping using flagellar antigens and assessed in relation to epidemiological data. Amplified fragment length polymorphism was found to be highly reproducible and 16 different profiles (each unique to the 15 incidents) were recognized. The method was also able to discriminate three subtypes within serotype H1, which is responsible for the majority of the emetic type of B. cereus food poisoning in England and Wales.
Wound infections due to Clostridium botulinum were not recognised in the UK and Republic of Ireland before 2000. C. botulinum produces a potent neurotoxin which can cause paralysis and death. In 2000 and 2001, ten cases were clinically recognised, with a further 23 in 2002, 15 in 2003 and 40 cases in 2004. All cases occurred in heroin injectors. Seventy cases occurred in England; the remainder occurred in Scotland (12 cases), Wales (2 cases) and the Republic of Ireland (4 cases). Overall, 40 (45%) of the 88 cases were laboratory confirmed by the detection of botulinum neurotoxin in serum, or by the isolation of C. botulinum from wounds. Of the 40 cases in 2004, 36 occurred in England, and of the 12 that were laboratory confirmed, 10 were due to type A. There was some geographical clustering of the cases during 2004, with most cases occurring in London and in the Yorkshire and Humberside region of northeast England.
In 2000, an unusual increase of morbidity and mortality among illegal injecting drug users in the UK and Ireland was reported and Clostridium novyi was identified as the likely source of the serious infection, although infections due to C. botulinum and Bacillus cereus were also reported. Because heroin was a possibile source of infection, this study investigated the microflora of heroin samples seized in England during 2000 and 2002. Two methods were developed for the examination of the microflora of heroin. The first consisted of suspension of the drug in maximum recovery diluent (MRD) which was inoculated directly into Clostridium Botulinum Isolation Cooked Meat Broth (CBI). The second method rendered the heroin soluble in citric acid, concentrated particulate material (and bacterial cells) by filtration and removed heroin residues by washing with citric acid and phosphate-buffered saline before placing the filter in CBI broth. Duplicate CBI broths from both methods were incubated without heating and after heating at 60°C for 30 min. Subcultures were made after incubation for 7 and 14 days on to eight different solid media. The methods were evaluated with heroin samples spiked with either C. botulinum or C. novyi spore suspensions; recovery of 10 spores in the original sample was demonstrated. Fifty-eight heroin samples were tested by citric acid solubilisation and 34 by the MRD suspension technique. Fifteen different gram-positive species of four genera were recognised. No fungi were isolated. Aerobic endospore-forming bacteria (Bacillus spp. and Paenibacillus macerans) were the predominant microflora isolated and at least one species was isolated from each sample. B. cereus was the most common species and was isolated from 95% of all samples, with B. licheniformis isolated from 40%. Between one and five samples yielded cultures of B. coagulans, B. laterosporus, B. pumilus, B. subtilis and P. macerans. Staphylococcus spp. were isolated from 23 (40%) samples; S. warneri and S. epidermidis were the most common and were cultured from 13 (22%) and 6 (10%) samples respectively. One or two samples yielded cultures of S. aureus, S. capitis and S. haemolyticus. The remainder of the flora detected comprised two samples contaminated with C. perfringens and two samples with either C. sordellii or C. tertium. Multiple bacterial species were isolated from 43 (74%) samples, a single species from the remaining 15. In 13 samples B. cereus alone was isolated, in one B. subtilis alone and in one sample B. pumilus alone. C. botulinum and C. novyi were not isolated from any of the heroin samples. Recommendations for the optimal examination of the microflora of heroin are given.
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