A Bacteriological Study of Vibrio cholerae Isolated from Rural Tertiary Care Hospital of Loni, Western Maharashtra.

Aim: Cholera is endemic in many parts of India and a major public health problem. The present study was carried out with the aims to understand biotype, serotype, phage type and drug resistance of Vibrio cholerae isolates obtained at a rural tertiary care hospital in Loni. Study Design: Descriptive retrospective study was carried out to study V. cholerae isolates from 544 faecal specimens of patients with acute gastroenteritis. Place and Duration of Study: The study was conducted during 2009-2012 at Rural Medical College of Pravara Institute of Medical Sciences, Loni, District Ahmednagar, Maharashtra, India. Methods: A total of 28 isolates of V. cholerae were included in the study. V. cholerae was identified by standard microbiological procedures. Biotyping, serotyping and phage typing was done. Antibiotic sensitivity testing was performed by Kirby- Bauer disc diffusion method. Results: V. cholerae strains were isolated from 28 faecal specimens. All the isolates were identified as V. cholerae O1 biotype El Tor serotype Ogawa and phage 27 was the predominant type. Male: Female ratio was 1:1.5 and high incidence was seen in 0-10 age group (35.71%). Maximal occurrence in monsoon season was recorded. All the isolates were resistant to co-trimoxazole, nalidixic acid and ampicillin. However maximum sensitivity was observed to norfloxacin (71.42%) followed by gentamycin (67.85%) and chloramphenicol (28.57%). Conclusion: A continuous surveillance for V. cholerae is required with respect to changing epidemiology and emergence of antibiotic resistance strains. The source and spread of infection should be investigated to decide the proper management strategies. Additionally, quality of water and status of sanitation should be monitored.

Epidemiology & antibiograms of Vibrio cholerae isolates from a tertiary care hospital in Chandigarh, north India.

Background & objectives: Cholera is endemic in Chandigarh and its surrounding areas. This retrospective study was undertaken over a period of nine years (January 1999-December 2007) from a tertiary care hospital in north India to understand the changing epidemiology aspects and antibiotic resistance patterns in Vibrio cholerae isolates. Methods: A total of 277 isolates of V. cholerae were included in the study. V. cholerae was identifi ed by standard microbiological procedures. Antibiotic sensitivity testing was performed by disc diffusion method and isolates phage typed. Results: All the isolates were identifi ed as V. cholerae O1 biotype El Tor serotype Ogawa; phage 27 was the predominant type. Men were more commonly affected with maximum number in the age group 0-5 yr. Majority of the isolates were resistant to furazolidone but sensitive to gentamicin and cefotaxime. Resistance pattern to amoxycillin was variable. Three isolates were found to be resistant to ciprofl oxacin. All the patients presented during June-October coinciding with the monsoon season and a majority were from suburbs. Interpretation & conclusions: The emergence of resistance amongst V. cholerae especially towards ciprofl oxacin may signifi cantly infl uence the control strategies in future outbreaks. Phage 27 remained the predominant type in all the years. Continuous surveillance with regard to drug resistance, early detection and a strong regional commitment may help contain the disease.

Occurrence, significance & molecular epidemiology of cholera outbreaks in West Bengal.

BACKGROUND & OBJECTIVE: Diarrhoeal disease outbreaks are causes of major public health emergencies in India. We carried out investigation of two cholera outbreaks, for identification, antimicrobial susceptibility testing, phage typing and molecular characterization of isolated Vibrio cholerae O1, and to suggest prevention and control measures. METHODS: A total of 22 rectal swabs and 20 stool samples were collected from the two outbreak sites. The V. cholerae isolates were serotyped and antimicrobial susceptibility determined. Pulsed- field gel electrophoresis (PFGE) was performed to identify the clonality of the V. cholerae strains which elucidated better understanding of the epidemiology of the cholera outbreaks. RESULTS: Both the outbreaks were caused by V. cholerae O1 (one was caused by serotype Ogawa and the other by serotype Inaba). Clinically the cases presented with profuse watery diarrhoea and dehydration. All the tested V. cholerae isolates were sensitive to tetracycline, gentamycin and azithromycin but resistance for ampicillin, co-trimoxazole, nalidixic acid, and furazolidone. PFGE pattern of the isolates from the two outbreaks revealed that they were clonal in origin. Stoppage of the source of water contamination and chlorination of drinking water resulted in terminating the two outbreaks. INTERPRETATION & CONCLUSION: The two diarrhoeal outbreaks were caused by V. cholerae O1 (Inaba/Ogawa). Such outbreaks are frequently seen in cholera endemic areas in many parts of the world. Vaccination is an attractive disease (cholera) prevention strategy although long-term measures like improvement of sanitation and personal hygiene, and provision of safe water supply are important, but require time and are expensive.

Epidemiological, microbiological & electron microscopic study of a cholera outbreak in a Kolkata slum community.

BACKGROUND & OBJECTIVE: Epidemics of cholera caused by Vibrio cholerae O1 or O139 have been reported from different parts of India. Factors such as unsafe water supply, poor environmental sanitation, indiscriminate defaecation and lack of personal hygiene are mainly responsible for continued transmission of this disease. We report here epidemiological and microbiological findings of a localized outbreak of cholera, which occurred during March and April 2004 in the eastern part of Kolkata city. METHODS: The affected slum area has a population of 4409, predominantly muslims. Patients suffering from acute watery diarrhoea attended the health outposts organized by National Institute of Cholera and Enteric Diseases, Kolkata and International Vaccine Institute, South Korea as part of a routine surveillance programme at the locality as well as the emergency medical camp organized by the Kolkata Municipal Corporation. Stool and water samples were collected and tested for diarrhoeagenic pathogens in the laboratory. Bacteriophages specific for V. cholerae were isolates and studied electron microscopically for morphology. RESULTS: A total of 89 diarrhoea cases were reported giving an attack rate of 2 per cent. V. cholerae O1 biotype ElTor, serotype Ogawa was isolated as a sole pathogen from 15 (15.8%) of 89 stool samples screened. Water samples (2 from tube wells, 3 from municipal taps and 1 from well) showed presence of coliform bacilli with high MPN (Most Probable Number) count. Bacteriophages specific to V. cholerae were isolated from 2 of 6 water samples examined. A leakage was detected in the main pipeline supplying drinking water to that area. INTERPRETATION & CONCLUSION: The outbreak was caused by V. cholerae O1 (Ogawa) biotype ElTor. The presence of phages in the water samples was an additional indicator for V. cholerae contamination in this community. Occurrences of such outbreaks support vaccination against cholera as an alternative strategy.

An el tor cholera outbreak amongst tribal population in Tripura.

An outbreak of acute diarrhoeal disease occurred in Dhalai and North Tripura district, Tripura during month of May 2004. An investigation was done to identify causative agent with anti microbial susceptibility pattern and to know the epidemiological feature. Overall attack rate and Case Fatality Rate (CFR) was 18.8%. and 6.9/1000 respectively. Vibrio cholerae O1 biotype El Tor, Ogawa was isolated as sole pathogen in 40% of hospitalized acute diarrhoea patient and from a water samples examined. The strains were sensitive to Tetracycline, Doxycycline, Norfloxacin, Ciprofloxacin, Chloramphenicol, and Azithromycin. Bad peridomestic sanitation, use of contaminated surface water along with low literacy, lack of personal hygiene, frequent movement might be the factor associated with persistence and spread of pathogen amongst tribal groups leading to outbreak of cholera.

Bacteriological profile of cholera in Tamil Nadu (1980-2001).

BACKGROUND & OBJECTIVE: In addition to Vibrio cholerae O1, a recently emerged non-O1 serotype, V. cholerae O139 has also been found to be responsible for epidemics of cholera. In the context of the changing etiology of cholera, the occurrence of different serotypes, biotypes and phage types of V. cholerae in Tamil Nadu is presented. METHODS: Between 1980 and 2001, 26,502 stool/rectal swabs from patients suspected to have cholera were processed for the presence of V. cholerae at the King Institute of Preventive Medicine, Chennai (Madras), Tamil Nadu. Serotypes, biotypes and phage types (Basu & Mukerjee and new phage typing method) of the isolates were determined. Antimicrobial susceptibility determination was included from 1997 onwards. RESULTS: Of the 26,502 stool/rectal swabs tested, 6035 (22.8%) specimens yielded V. cholerae. 4,046 (67%) of them were O1 serotype; followed by 1529 (25.3%) O139 serotype and 448 (7.4%) non-O1 serotypes other than O139 were encountered. Twelve specimens yielded rough strains of V. cholerae. All V. cholerae O1 were the biotype ElTor and the predominant serotype was Ogawa (95.9%). After the initial explosive epidemic by O139 serotype in late 1992 and early 1993 occurrence of this serotype had declined. Resurgence of this new serotype was observed in 1997. O1 domination was observed during 1995 and 1996. The new phage typing scheme for V. cholerae O1 was able to differentiate the isolates into 22 types, type 27 (68.2%) being the predominant one followed by type 26 (12.3%). In Basu & Mukerjee scheme, the isolates were clustered between two types--type 2 (34%) and type 4 (61%). Further, about 5 per cent of them were untypeable. All but a few of the isolates irrespective of serotype, were susceptible to chloramphenicol, tetracycline, gentamicin and ciprofloxacin. 97 per cent of the O1 strains and 48.9 per cent of the O139 strains were resistant to cotrimoxazole. INTERPRETATION & CONCLUSION: V. cholerae O139 might have the ability to survive during interepidemic periods. Both V. cholerae O1 and O139--the two serotypes with epidemic potential seem to be firmly established in this region. This situation warrants constant surveillance.

Distribution of phage type of Vibrio cholerae O1 biotype ElTor in Indian scenario (1991-98).

During the period 1991-98, distribution of biotype, serotype and phage type of V. cholerae O1 strains isolated from different parts of the country and referred to the National Institute of Cholera and Enteric Diseases, Calcutta were studied. Of the 8101 strains received, 5613 (69.2%) were subjected to phage typing. All these strains belonged to the biotype ElTor and Ogawa was the predominant serotype (96.08%). The strains were clustered into only two types--types 2 and 4 and around 10 per cent strains remained untypable. However, using the new scheme, all these strains were found to be typable and 8 major types were recognized of which type number 27 was the predominant type (66.12%). The distribution of a common type throughout the country suggests that a particular clone of V. cholerae O1 is probably circulating all over India. A constant monitoring through phage typing is necessary to observe the emergence of any new clone of V. cholerae O1 in India.

An El Tor cholera outbreak in Maldah district, West Bengal.

An outbreak of cholera occurred in Maldah district, West Bengal during July-August 1998. Attack rate was 34/1000. Cases were more (59.3%) amongst adults (> 15 years.). V. cholerae 01 biotype E1 Tor serotype ogawa was isolated as a single pathogen from 52.9% (9/17 samples examined). All V. cholerae strains belonged to phage type 2 (Basu and Mukherjee scheme) and type 27 (new phage type scheme). The strains were resistant to co-trimoxazole, furazolidone, ampicillin, streptomycin and nalidixic acid.

Isolation of Vibrio cholerae 0139 phages to develop a phage typing scheme.

Five V. cholerae 0139 phages isolated from different parts of India have been used for phage typing study. A strain isolated from Nagpur city (NPR-4) was used as the host for phage propagation. All but one of the 260 strains of V. cholerae 0139 were found to be typeable and could be clustered into 8 distinct phage types as revealed by lytic patterns. Phage type 1 was the predominant type (61.15%) followed by type 2 (18.46%). The strains isolated from Madras exhibited 7 out of 8 phage types. These newly isolated phages could be adopted for phage typing of V. cholerae 0139 strains as an epidemiological tool.

Biological activity & interaction of Vibrio cholerae bacteriophages in rabbit ileal loop.

A set of ten V. cholerae EITor phages is in routine use for phage typing of V. cholerae O1 biotype EITor strains. These phages were used in rabbit ileal loop experiment to investigate whether these phages have any prophylactic value as regards their lytic capability on V. cholerae strains. The phages were found to have no prophylactic use as they were unable to lyse the standard bacterial strain V. cholerae MAK 757.

Outbreak of cholera due to Vibrio cholerae 01 in Orissa state.

During May-June 1993, an outbreak of acute diarrhoea resulting in deaths primarily in adults was reported in two districts of Orissa state. Epidemiological and microbiological investigations revealed that this outbreak was caused by V. cholerae 01 biotype EITor. V. cholerae 01 strains were uniformly resistant to furazolidone.

Validity of new phage typing scheme against Vibrio cholerae 01 biotype ElTor strains.

A total of 538 strains of V. cholerae 01 biotype ElTor were phage typed by the conventional Basu and Mukerjee and also the new typing scheme developed at the National Institute of Cholera and Enteric Diseases, Calcutta. The strains could be clustered into seven types by the new scheme as against only two by the conventional method. The results provide conclusive evidence on the validity of the new scheme for phage typing of V. cholerae strains.

An outbreak of acute diarrhoeal disease amongst tribal population in Tripura.

A massive outbreak of acute diarrhoeal diseases occurred during March-April, 1992 in the north district of Tripura. Investigation of the outbreak revealed Vibrio cholerae 01 biotype ElT or as the main etiologic agent in 50 per cent of patients. The outbreak which started amongst the tribal population might have spread due to prevailing illiteracy, poverty, low personal and domestic hygiene and vulnerable water sources (chhara water).