Nosocomial diarrhoea in the elderly due to enterotoxigenic Clostridium perfringens

Effects of Bile Acids and Nisin on the Production of Enterotoxin by Clostridium perfringens in a Nutrient-Rich Medium

Clostridium perfringens is the second most common cause of bacterial foodborne illness in the United States, with nearly a million cases each year. C. perfringens enterotoxin (CPE), produced during sporulation, damages intestinal epithelial cells by pore formation, which results in watery diarrhea. The effects of low concentrations of nisin and bile acids on sporulation and toxin production were investigated in C. perfringens SM101, which carries an enterotoxin gene on the chromosome, in a nutrient-rich medium. Bile acids and nisin increased production of enterotoxin in cultures; bile acids had the highest effect. Both compounds stimulated the transcription of enterotoxin and sporulation-related genes and production of spores during the early growth phase. They also delayed spore outgrowth and nisin was more inhibitory. Bile acids and nisin enhanced enterotoxin production in some but not all other C. perfringens isolates tested. Low concentrations of bile acids and nisin may act as a stress signal for the initiation of sporulation and the early transcription of sporulation-related genes in some strains of C. perfringens, which may result in increased strain-specific production of enterotoxin in those strains. This is the first report showing that nisin and bile acids stimulated the transcription of enterotoxin and sporulation-related genes in a nutrient-rich bacterial culture medium.

Spread of a large plasmid carrying thecpegene and thetcplocus amongstClostridium perfringensisolates from nosocomial outbreaks and sporadic cases of gastroenteritis in a geriatric hospital

To investigate two clusters of diarrhoea cases observed in our geriatric hospital wards, the faecal specimens were analysed. Reversed passive latex agglutination assay revealed that 63·2% and 41·7% of the faecal specimens from each cluster were positive forClostridium perfringensenterotoxin. PCR assay revealed that 71·4% and 68·8% ofC. perfringensisolates from each cluster were positive for the enterotoxin gene (cpe). These observations suggested that both the clusters were outbreaks caused by enterotoxigenicC. perfringens. Subsequent pulsed-field gel electrophoresis analysis revealed that the two outbreaks were caused by differentC. perfringensisolates. However, these outbreak isolates as well as other sporadic diarrhoea isolates shared a 75-kb plasmid on which thecpegene and thetcplocus were located. The 75-kb plasmid had horizontally spread to variousC. perfringensisolates and had caused outbreaks and sporadic infections. However, the site and time of the plasmid transfer are unclear.

Comparative analysis of prevalence, risk factors, and molecular epidemiology of antibiotic-associated diarrhea due to Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus

We prospectively studied the comparative epidemiology and risk factors for Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus antibiotic-associated diarrhea (AAD). Four thousand six hundred fifty-nine inpatient fecal specimens (11 months) were tested for C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus by Vero cell assay, enzyme-linked immunosorbent assay, and growth on fresh blood agar, respectively. Two distinct age-, sex-, and location-matched control patient groups were used for multivariate logistic regression risk factor analyses: symptomatic patients who were AAD pathogen negative and asymptomatic patients with histories of recent antimicrobial therapy. All AAD pathogen isolates were DNA fingerprinted. In AAD cases, the prevalences of C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus were 12.7%, 3.3%, and 0.2%, respectively (15.8% overall). Age of >70 years was a common risk factor. Other risk factors for infective AAD and C. difficile AAD included length of hospital stay and use of feeding tubes (length of stay odds ratios [OR], 1.017 and 1.012; feeding tube OR, 1.864 and 2.808). Female gender and use of antacids were significantly associated with increased risk of C. perfringens AAD (OR, 2.08 and 2.789, respectively), but unlike what was found for C. difficile AAD, specific antibiotic classes were not associated with increased risk. A limited number of genotypes caused the majority of C. difficile and C. perfringens AAD cases. Similar to what was found for C. difficile AAD, there was epidemiological evidence of C. perfringens AAD case clustering and reinfection due to different strains. C. difficile AAD was approximately 4 and 60 times more common than C. perfringens AAD and S. aureus AAD, respectively. Risk factors for these AAD pathogens differed, highlighting the need to define specific control measures. There is evidence of nosocomial transmission in cases of C. perfringens AAD.

Genetic diversity of Clostridium perfringens type A isolates from animals, food poisoning outbreaks and sludge

BACKGROUND

Clostridium perfringens, a serious pathogen, causes enteric diseases in domestic animals and food poisoning in humans. The epidemiological relationship between C. perfringens isolates from the same source has previously been investigated chiefly by pulsed-field gel electrophoresis (PFGE). In this study the genetic diversity of C. perfringens isolated from various animals, from food poisoning outbreaks and from sludge was investigated.

RESULTS

We used PFGE to examine the genetic diversity of 95 C. perfringens type A isolates from eight different sources. The isolates were also examined for the presence of the beta2 toxin gene (cpb2) and the enterotoxin gene (cpe). The cpb2 gene from the 28 cpb2-positive isolates was also partially sequenced (519 bp, corresponding to positions 188 to 706 in the consensus cpb2 sequence). The results of PFGE revealed a wide genetic diversity among the C. perfringens type A isolates. The genetic relatedness of the isolates ranged from 58 to 100% and 56 distinct PFGE types were identified. Almost all clusters with similar patterns comprised isolates with a known epidemiological correlation. Most of the isolates from pig, horse and sheep carried the cpb2 gene. All isolates originating from food poisoning outbreaks carried the cpe gene and three of these also carried cpb2. Two evolutionary different populations were identified by sequence analysis of the partially sequenced cpb2 genes from our study and cpb2 sequences previously deposited in GenBank.

CONCLUSION

As revealed by PFGE, there was a wide genetic diversity among C. perfringens isolates from different sources. Epidemiologically related isolates showed a high genetic similarity, as expected, while isolates with no obvious epidemiological relationship expressed a lesser degree of genetic similarity. The wide diversity revealed by PFGE was not reflected in the 16S rRNA sequences, which had a considerable degree of sequence similarity. Sequence comparison of the partially sequenced cpb2 gene revealed two genetically different populations. This is to our knowledge the first study in which the genetic diversity of C. perfringens isolates both from different animals species, from food poisoning outbreaks and from sludge has been investigated.

Usefulness of a combination of pulsed-field gel electrophoresis and enrichment culture in laboratory investigation of a foodborne outbreak due to Clostridium perfringens

Clostridium perfringens is ubiquitous in nature and normally detectable in human stools. Therefore, it is difficult to perform specific microbiologic diagnosis in foodborne outbreaks, particularly when only a few cultures are detected from fecal specimens. Usually, it has been necessary to detect over 10(6) spores/g of fecal sample as a diagnostic criterion of diarrhea due to C. perfringens. A relatively large foodborne outbreak occurred in Osaka City, Japan in October 2001. Although C. perfringens was suspected as the causal agent, four to seven days had passed after the onset of symptoms before fecal specimens were brought into our laboratory. The positive rate obtained by direct plating was quite low (13/83). We attempted to detect the organisms using enrichment culture after 75 degrees C 20 min heat-treatment, and C. perfringens enterotoxin gene (cpe)-positive strains were isolated from 53 of 81 samples. Pulsed-field gel electrophoresis (PFGE) and serotyping showed that 36 (67.9%) of these 53 strains had indistinguishable PFGE patterns and the same serotype, TW69. Our experience indicates that the enrichment culture could be useful for laboratory confirmation of a C. perfringens foodborne outbreak if it is used with adequate molecular epidemiologic methods.

Detection of Clostridium difficile cytotoxin and Clostridium perfringens enterotoxin in cases of diarrhoea in the community

Faecal specimens from 843 cases of diarrhoea in the community were tested for the presence of Clostridium difficile cytotoxin and Clostridium perfringens enterotoxin. C. difficile cytotoxin was detected in faecal specimens from 0.6 % of cases aged at least 2 years by using a Vero cell assay. Factors associated with detection of C. difficile cytotoxin were antibiotic therapy, age over 60 years and living in a home with other elderly people. Three methods were used for the detection of C. perfringens enterotoxin: a Vero cell assay, a commercial (TechLab) enzyme immunoassay (EIA) and an in-house EIA. The lower level of detection of pure C. perfringens enterotoxin in buffer was 0.01 micro g ml(-1) by the TechLab EIA and 1.0 micro g ml(-1) by the Vero cell assay. C. perfringens enterotoxin was detected by using the TechLab EIA in faecal specimens from 2.5 % of cases. This commercial EIA was less sensitive than the in-house EIA, detecting only 31 % of positive cases, but was specific and could be used for outbreak investigation by routine diagnostic laboratories. Age over 60 years was a factor associated with C. perfringens enterotoxin detection; this age group may be targeted for testing.

Molecular typing of Clostridium perfringens from a food-borne disease outbreak in a nursing home: ribotyping versus pulsed-field gel electrophoresis

In 1998, 21 inhabitants of a German nursing home fell ill with acute gastroenteritis after consumption of minced beef heart (P. Graf and L. Bader, Epidemiol. Bull. 41:327-329, 2000). Two residents died during hospital treatment. Seventeen Clostridium perfringens strains were collected from two different dishes and from patients' stool samples and autopsy materials. A majority of these isolates was not typeable by restriction fragment length polymorphism-pulsed-field gel electrophoresis (PFGE). Subsequent ribotyping of C. perfringens distinguished four different groups. The same ribopattern was detected in a minced beef heart dish, in autopsy material from the two deceased patients, and additionally in stool samples from six further residents who had fallen ill with diarrhea. Three further ribopatterns from food and autopsy materials could be differentiated. As chromosomal macrorestriction with subsequent PFGE is generally regarded more useful than ribotyping for molecular strain analysis, four selected isolates were lysed in parallel with a standard protocol and two nucleases inhibiting modifications. Neither of these methods could differentiate all of the isolates. These results suggest that PFGE with the current standard protocols is not able to characterize all C. perfringens isolates from food-borne disease investigations and that ribotyping is still a helpful method for molecular identification of clonal relationships.

Molecular epidemiology of Clostridium perfringens related to food-borne outbreaks of disease in Finland from 1984 to 1999

From 1975 to 1999, Clostridium perfringens caused 238 food-borne disease outbreaks in Finland, which is 20% of all such reported outbreaks during these years. The fact that C. perfringens is commonly found in human and animal stools and that it is also widespread in the environment is a disadvantage when one is searching for the specific cause of a food-borne infection by traditional methods. In order to strengthen the evidence-based diagnostics of food poisonings suspected to be caused by C. perfringens, we retrospectively investigated 47 C. perfringens isolates by PCR for the cpe gene, which encodes enterotoxin; by reversed passive latex agglutination to detect the enterotoxin production; and by pulsed-field gel electrophoresis (PFGE) to compare their genotypes after restriction of DNA by the enzymes SmaI and ApaI. The strains were isolated during 1984 to 1999 from nine food-borne outbreaks of disease originally reported as having been caused by C. perfringens. In seven of the nine outbreaks our results supported the fact that the cause was C. perfringens. Our findings emphasize the importance of a more detailed characterization of C. perfringens isolates than mere identification to the species level in order to verify the cause of an outbreak. Also, to increase the probability of finding the significant cpe-positive C. perfringens strains, it is very important to isolate and investigate more than one colony from the fecal culture of a patient and screen all these isolates for the presence of the cpe gene before further laboratory work is done.

Evidence for antibiotic induced Clostridium perfringens diarrhoea

Clostridium difficile is a well documented cause of antibiotic associated diarrhoea in hospitalised patients, but may account for only approximately 20% of all cases. This leader reviews the current knowledge and understanding of the pathogenesis, epidemiology, and diagnosis of non-food borne Clostridium perfringens diarrhoea. Although enterotoxigenic C perfringens has been implicated in some C difficile negative cases of antibiotic associated diarrhoea, C perfringens enterotoxin detection methods are not part of the routine laboratory investigation of such cases. Testing for C perfringens enterotoxin in faecal samples from patients with antibiotic associated diarrhoea and sporadic diarrhoea on a routine basis would have considerable resource implications. Therefore, criteria for initiating investigations and optimum laboratory tests need to be established. In addition, establishing the true burden of C perfringens antibiotic associated diarrhoea is important before optimum control and treatment measures can be defined.

Comparison of protocols for pulsed-field gel electrophoresis of Clostridia

Genotyping of bacterial strains via pulsed-field gel electrophoresis has to be considered an important tool for epidemiological investigations in food hygiene as well as in other areas. Yet, a major disadvantage of this method is its long duration. Therefore, rapid procedures for DNA isolation and restriction are being sought. One such protocol was modified and further shortened to two days. This short protocol was used for macrorestriction analysis of 34 strains of 25 different Clostridium species. Parallel analyses were performed using a conventional 5-day protocol in order to compare the long and the short method by running the DNA samples obtained via both protocols on the same gel. In the case of nine strains, none of the two methods yielded satisfactory results, whereas for three strains the long protocol proved to be preferable to the short one. Comparable results were obtained using both methods in the case of 22 strains belonging to 17 different Clostridium species.

Short protocol for pulsed field gel electrophoresis of a variety of Clostridia species

While pulsed field gel electrophoresis has become an important tool for genotyping of bacteria, one of its drawbacks is that standard methods are rather time-consuming. In order to overcome this problem, shortened procedures for DNA preparation have been developed for some bacterial species. The aim of this study was to examine if a short procedure used for pulsed field gel electrophoresis of Clostridium botulinum could be applied to other Clostridia species. For this, the protocol was modified and used to prepare the DNA of 34 strains of 25 different Clostridia species. In contrast to a standard procedure, which takes at least 5 days from DNA extraction to completion of the electrophoresis, this protocol yielded results within 2 days. In order to directly compare the results of the short protocol with those of the standard, long procedure, parallel DNA preparations were performed using both methods and the two DNA samples thus obtained per strain were then run on the same gel. Briefly, the procedure was as follows. After embedding the bacterial cells in agarose, the agarose blocks were incubated for 1 h in lysis solution containing lysozyme, mutanolysin, lysostaphin and RNase. This was followed by a 1-h proteinase K treatment. Then, slices were cut from the agarose blocks and washed for 15 min in TE buffer, these washes were repeated four times with fresh TE. After a 2-h restriction with SmaI, electrophoresis was carried out overnight.