ABSTRACT
Background: To distinguish the different types of pathogenic E. coli with other non-pathogenic E.coli in the intestine is extremely important in diagnosis. Up to date there are at least six types of E. coli that causes diarrhea. Objectives: We have designed a multiplex PCR assay for the direct detection of 6 categories of diarrheagenic Escherichia coli. Subjects and method: This techniques proved to be specific and rapid for detecting virulence genes from Shiga toxin-producing (stx and eae), enteropathoogenic (eae), enterotoxigenic (elt, est), ennteroinvasive (ipaH), enteroaggregative (aggR), and diffuse adherent (daaE) Esscherichia coli. The technique was applied to 295 clinical stool specimens. Results: The highest prevalence is EAggEC with 51 positive samples.(17.29%), 48 EIEC (16.27%), 17 EPEC (5.76%), 8 ETEC (LT) (2.71%), 5 ETEC (ST) (1.69%), 1 DAEC (0.34%), no STEC positive and 19 mix infections (6.44%). Conclusion: Multiplex PCR assay is a quick and highly accuurate technique. It is not only specific but can also amplify 7 virulence genes of diarrrheagenic E.coli at the same time. This method would offer an effective alternative to traditional culture methods for the identification and differentiation of human diarrhaegenic Escherichia coli.
ABSTRACT
Background: Classification of vibriophages has been applied for epidemiological surveillance of cholera, but in Vietnam, there was virtually no knowledge about it. It is very important to determine whether the strains have common origin or different origins.Objectives: To classify vibriophages isolated from environmental surface water samples in Thai Binh in order to monitor cholera outbreaks. Subjects and method: Three vibriophages (84, 87, and 811) were collected from surface water samples in Thai Binh in 2006. Electronic microscopy was used to compare the size and morphology of Vibrio phages. Also, the structures of genomic DNA of vibriophages were compared by hind III digestion pattern and Southern blotting. Results: Vibriophages S4 and S11 isolated from Thai Binh were similar to kappa phage (a phage produced by V. cholerae 01 EI Tor strain), phage IV (a phage produced by V. cholerae 01 classical strain) in term of morphology and genome and were the same shape and DNA dimension of phage 1823 isolated from V. cholerae O139 strain in India and Bangladesh. Conclusion: Phage 84, 81 isolated from Thai Binh were new kinds of vibriophage isolated in Viet Nam. These findings were very useful for supervising and controlling cholera outbreaks in Vietnam.
Subject(s)
ClassificationABSTRACT
Background: In countries that cholera outbreaks commonly occurs, surveillance of surface water is important to control the epidemics. Kappa phage (K139) of Vibrio cholerae is related to epidemic El Tor and O139 strains in various countries. Objectives: To study the relationships between V. cholerae 01 and vibriophages in surface water in Thai Binh and Hai Phong city and to determine the predictors of cholera outbreaks. Subjects and method: Total of 82 water samples were collected by shrimp swab method in Hai Phong and Thai Binh in June and September 2007, where cholera outbreaks occurred. The enriched culture method and direct peR were applied to define the relationships between vibriophages and V. cholerae 01 in surface water. Results: The rates of detecting kappa junction with chromosomes of V. cholerae 01 in Hai Phong and Thai Binh were 10% and 15% in June 2007, 35% and 41% in September 2007. The rates of detecting vibriophages in Hai Phong and Thai Binh were 15% and 15% in June 2007, 25% and 36% in September 2007. The rates of Fs1 and Fs2 detected by PCR method were 70% and 100% in Hai Phong at June and September 2007, and were 57% and 100% in Thai Binh at June and September 2007, respectively. V. cholerae 01, O139 weren\u2019t found in water samples. Conclusion: The presences of vibriophages (kappa phage and fs1 fs2) in surface water contaminated with V. cholerae 01 were dependent on the ability of the vibriophages to infect and lyse these bacteria. Vibriophages played a role in the transfer of cholera toxin and pathogenic factors. Surveillance by detecting V. cholerae 01 and vibriophages in surface water may be a feasible means of predicting outbreaks of cholera before a significant number of cases occur.
Subject(s)
Surface WatersABSTRACT
Background: Diarrhea is a leading cause of death in children under 5 years old, especially in developing countries. About 12.600 children die because of diarrhea everyday in Asia, Africa and Latin-America. Objective: To identify the main organism that causes diarrhea in children under 5 years old. Subject and Method: The etiology agents of diarrheal children under 5 years old admitted to the Pediatric Hospital in Hai Phong city were studied in the period from September 2006 to August 2007. A total of 968 children were examined for diarrheagenic Escherichia coli (DEC), Salmonella, Shigella, Vibrio, Aeromonas, Campylobacter, these pathogens as being significant bacteria associated with diarrhea. A total of 212 out of 968 cases were positive for bacteria. Result: The main pathogens were diarrheagenic Eschierichiacoli 153 (15.7%), Salmonella 12 (1.24%), Shigella 32 (3.3%). Vibirio paraheamolyticus 1(0.1%), Aeromonas 8 (0.8%), Campylobacter 6(0.6%) from rectal swabs and no Vibrio cholerae was found. The multiplex PCR assays for the identification of DEC was developed. DEC was classified into 6 categories with frequencies of EPEC 3.9%, ETEC 4.4%, EIEC 0.6%, EAggEC 6.7%, DAEC 0.1%, no EHEC was identified. Conclusion: An analysis of incidence of enteropathogens with respect to seasonal variant demonstrated that the frequencies of isolation of etiology agents mainly in July, August and September. This study also showed that diarrheagenic- Escherichia coli is the main organism causing diarrhea in children under 5 years old.
Subject(s)
DiarrheaABSTRACT
Background:The kit Crystal VC is a Lateral Flow Imunochromatographic test for the qualitative determination of Lipopolysacharide (LPS) antigen of both V cholerae 01 and 0139, from stool specimens, using monoclonal antibodies specific to V. cholerae 01 and 0139 LPS. It does not include culturing the specimen and is performed without the need for sophisticated laboratory equipment. \r\n', u'Objectives: To evaluate the dipstick kit for detection of V. cholerae 01. Subjects and methods: A total of 65 stool specimens from diarrhea patients were tested to determine V. cholerae 01 by Crystal VC kit. \r\n', u'Results: The sensitivity of the 01 dipstick compared to culture was 93.7%, with a specificity of 87.7%. Crystal VC kit is simple, sensitivity, specific and does not require culturing procedures, making it suitable for direct detection of V. cholerae in clinical specimens. Also, the test only requires 10 minutes to complete.\r\n', u'Conclusions: The dipsticks test may be helpful in confirming clinically suspected cholera cases, especially during the start of an outbreak. Once a cholera outbreak has been confirmed, large scale preventive measures could be mobilized to minimize morbidity and mortality. \r\n', u'
ABSTRACT
Background: Food-born bacteria can be present in raw materials or contaminated foods during process and storage. Shrimp paste is a popular food in Viet Nam, but there are no studies on the hygiene and safety of this food. Objectives: To identify the microbial contamination of commercial shrimp paste available in Ha Noi City. Materials and method: A total of 50 shrimp paste samples were collected randomly from markets around Ha Noi City. Enumeration and isolation methods were used to determine the microbial contamination in these samples. Results: 100% of the samples were contaminated with Clostridium perfringens and Candida albicans. 10% of samples were contaminated with Coliform. Other pathogenic bacteria, including Escherichia coli, Salmonella, Staphylococcus aureus, Vibrio parahaemolyticus and Vibrio cholerae were not found in shrimp paste samples. Conclusion: Evaluation of microbial contamination in popular foods such as shrimp paste should be done regularly to prevent food-born diseases in the community.