A prospective study of phage types & biotypes of Salmonella enterica serotype Typhi isolated from hospitalized children in Kolkata, India.

BACKGROUND & OBJECTIVES: Kolkata and its suburbs in eastern India faced an epidemic of typhoid fever in 1990. A prospective, hospital and laboratory based study over a period of 12 yr (1990-2001), on the phage typing and biotyping pattern of Salmonella enterica serotype Typhi was carried out, to see if there has been a change. METHODS: A total of 338 S. enterica serotype Typhi isolates from 1491 blood samples were phage typed and biotyped. The mean age of isolation was calculated. RESULTS: The age distribution of subjects (neonates to 12 yr) has been analysed. Of the 338 (22.7%) isolates obtained, eight different S. enterica serotype Typhi phage types were detected. Biotype I (95.8%) was more prevalent as compared to biotype II (4.1%). Phage type E1 was the commonest phage type in Kolkata and its suburbs. INTERPRETATION & CONCLUSION: The mean age at isolation was found to be 6.7 +/- 3.3 yr. Biotype I was predominant and it was of interest that all strains of phage type E1 belonged to biotype I.

Decreasing trend in the occurrence of Salmonella enterica serotype Typhi amongst hospitalised children in Kolkata, India during 1990-2000.

In a prospective hospital based surveillance, 1454 children clinically diagnosed as typhoid fever were enrolled during the period between 1990 to 2000. Of them 336 (23.1%) children were positive for Salmonella enterica serotype Typhi by blood culture. A declining trend of hospitalization and identification of the pathogen was observed from 1992 to 2000 as compared to 1990-1991. A declining trend of resistance to the commonly used anti-typhoid drugs was seen in the S. enterica serotype Typhi isolates. Recently in 2000, nine strains were detected as ciprofloxacin resistant. Misuse and overuse of ciprofloxacin for the treatment of typhoid fever influenced the development of ciprofloxacin resistant strains of S. enterica serotype Typhi in and around Kolkata.

Isolation of Salmonella enterica serotypes from children with diarrhoea in Calcutta, India.

The prevalence of Salmonella enterica serotypes, antimicrobial susceptibility, and phage typing of serovers were studied. Clinical presentations of the infected cases were also examined. The study was carried out during August 1993-September 1996 in and around Calcutta, India. In total, 1,025 faecal samples from hospitalized diarrhoeal children were screened for enteropathogens. Four S. enterica serotypes were identified in 157 (15.3%) cases as a single pathogen. S. enterica serotype Typhimurium was detected in 110 (70%) cases. S. Seftenberg, S. Infantis, and S. Virchow were detected in 28 (17.8%), 14 (8.9%), and 5 (3.2%) cases respectively. S. Typhimurium was isolated from 11 (3.2%) non-diarrhoeal control children. All of these children had acute watery diarrhoea, and 5% of them had severe dehydration, 40% had some dehydration, and 55% had no dehydration. Vomiting, fever, and diffused pain in abdomen were the associated presentations of these children. Most (95%) of them recovered with oral rehydration therapy only and without any antibiotics. In-vitro susceptibility testing showed that 120 of the 121 S. Typhimurium strains isolated from cases and controls were resistant to the commonly-used drugs. Thirteen of the 121 strains were phage-typeable and belonged to the phage type 193. However, no clinical or epidemiological significance could be established with these typeable strains. The findings of the study indicate that diarrhoeagenic Salmonella is one of the major pathogens causing diarrhoeal diseases in eastern India.

Value of faecal leucocyte count as an indicator of invasiveness in mucoid diarrhoea.

Importance of faecal leucocyte count as an indicator of invasiveness in mucoid diarrhoea was studied. A total of 290 faecal specimen, 170 from mucoid diarrhoea and 120 from watery diarrhoea were examined for faecal leucocyte count under high power field (hpf) from rural children below four years of age during the period from November 1992 to October 1995. Faecal leucocyte count > 10/hpf was noted in 45.9% of mucoid diarrhoea as against 19.2% of watery diarrhoea (p < 0.0001) samples. From faecal samples with > 10 faecal leucocyte count, invasive pathogens could be recovered in 19 (24.5%) to none of 23 patients with watery diarrhoea (p < 0.006 Fisher exact test). This sample test appears to be of value as an indicator of invasiveness in mucoid diarrhoea in the absence of culture facility.

Comparison between the multiplex PCR, sensitivity to biotype specific phages & polymyxin B for biotyping of Vibrio cholerae O1.

A total of 196 Vibrio cholerae O1 strains isolated between 1970 and 1996 were biotyped by multiplex PCR, susceptibility to polymyxin B and sensitivity to biotype specific phages. We modified the multiplex PCR by increasing the primer concentration of tcpA to improve the results. Comparison of the results of modified multiplex PCR and sensitivity to biotype specific phages and to polymyxin B showed that multiplex PCR was as efficient as phage typing for biotyping of V. cholerae O1. All the strains of V. cholerae O1 could be accurately distinguished based on polymyxin B sensitivity. Thus our results show that susceptibility of strains of V. cholerae O1 to polymyxin B is the easiest method to biotype V. cholerae O1 and is feasible in most laboratories when compared with multiplex PCR and sensitivity to biotype specific phages.

Multi-drug resistant typhoid fever with diarrhea.

OBJECTIVE: To provide information about the characteristics of diarrheal stool in multi-drug resistant typhoid fever and observe the clinical course after treatment with furazolidone or ciprofloxacin. SETTING: Hospital based. SUBJECTS AND METHODS: Twenty one male children who were positive for multi-drug resistant S. typhi by blood and stool cultures, having diarrhea at the time of hospitalization comprised the subjects. Serum and stool electrolytes were estimated. Stool samples were also processed to detect established enteropathogens, leukocytes and red blood cells. Children were treated either with furazolidone or ciprofloxacin and evaluated till recovery. RESULTS: Mean (+/- SD) pre-admission duration of fever and diarrhea of these cases were 19.1 (+/- 5.6) and 15.8 (+/- 4.6) days, respectively. Stool character in 81% of the patients was watery with mean (+/- SD) volume of stool 51.4 (+/- 25.1) ml per kg body weight in the first 24 hours of observation. Leukocyte count varied between 20-49 per high power field in 66.7% stool samples. Occult blood was present in only 19% cases. Fecal red blood cells in high power field were detected in 52.4% cases. Mean fecal electrolytes (mmol/liter) were as follows: sodium-53.8, potassium-51.4, chloride-41.6 and total CO2-24.3. Most of the children (71.4%) had no dehydration and had normal serum electrolytes. The isolated strains of S. typhi were multi-drug resistant. These children were treated successfully either with furazolidone or ciprofloxacin. CONCLUSION: The stools of multi-drug resistant typhoid fever patients were watery with little blood. Their electrolyte contents were more similar to the diarrheal stool seen in shigellosis rather than cholera. Uncontrolled observations revealed that children recovered with furazolidone or ciprofloxacin therapy.

Distribution of age-specific rotavirus antibody in human: a hospital-based study in Calcutta.

Sera obtained from 332 non-diarrhoeic individuals belonging to different age groups were tested by enzyme-linked immunosorbent assay method for detection of rotavirus antibody. All the sera were found to contain rotavirus antibody in varying titres, the highest being recorded in neonates which declined to the lowest by the age of 6 months with a rapid rise during the next 5 years. This study indicates the acquisition of rotavirus antibody in different age groups.

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.

Value of a single Widal test in the diagnosis of typhoid fever.

Results of a single Widal test in patients with bacteriologically confirmed typhoid fever (116), clinically suggestive but culture negative fever (170) and non-typhoidal febrile illness (98) and in normal control children (54) were analysed. Positive Widal test (antibody titre against S. typhi O antigen of 1:160) was recorded in 61.2 per cent of patients with bacteriologically confirmed typhoid fever and in 58.8 per cent with culture negative but clinically suggestive typhoid fever. In contrast, the same titre was observed in 10.2 per cent patients with other febrile illnesses of known etiology and in 1.8 per cent of normal children. Differences in the positivity of Widal test in patients with bacteriologically confirmed typhoid fever and clinically suggestive but culture negative fever were highly significant (P < 0.000001) when compared to that of patients with non-typhoidal febrile illnesses and normal controls. High specificity and positive predictive value in 1:160 dilution makes the Widal test acceptable as a diagnostic tool.

Prospective study of nosocomial enteric infections in a pediatric hospital, Calcutta.

Hospital acquired enteric infections were investigated by studying 3138 children under 5 years of age who were admitted without diarrhea in nine medical words of a pediatric hospital, Calcutta during the period between March and September 1987. Three hundred and twenty (10.2%) children developed nosocomial diarrhea during their hospital stay. Fecal samples from 178 nosocomial diarrhea, 345 hospitalized diarrhea cases, 178 hospital controls and 200 outpatient controls were collected for detection of established enteropathogens. There were no statistically significant differences in the detection of most of the enteropathogens from fecal samples of nosocomial diarrhea, hospitalized diarrhea and hospital controls. Enteric pathogens were detected at a higher frequency (statistically significant) from fecal samples of nosocomial diarrhea cases as compared to outpatient controls. This study highlights the importance of most of the enteropathogens like Shigella, Salmonella, rotavirus, enteropathogenic E. coli as the cause of hospital cross infection. This study reinforces the importance of developing preventive measures in order to reduce the frequency of illness.

Occurrence of multi-drug resistant Salmonella typhi in Calcutta.

Blood and faecal samples were collected from 122 hospitalised patients of Calcútta clinically suspected to have enteric fever, for isolation of S. typhi. It was isolated from 34.4, 4.9 and 4.1 per cent patients by blood culture, stool culture and by both respectively. The in vitro drug susceptibility testing showed that all the isolates were resistant to chloramphenicol, ampicillin and trimethoprim-sulphamethoxazole, but were uniformly susceptible to ciprofloxacin, norfloxacin and furazolidone. In view of the appearance of multi-drug resistant S. typhi in Calcutta, great care should be exercised in the use of newer quinolone derivatives.

Nosocomial rotavirus diarrhea in two medical wards of a pediatric hospital in Calcutta.

One hundred eighty nine children suffering from different medical problems were admitted in two wards of a pediatric hospital in Calcutta during the period between November 18, 1985 and February 10, 1986. Amongst them, 36 children developed nosocomial diarrhea and rotavirus was detected from 80.5% of the cases. The nosocomial rotavirus diarrhea cases had lesser frequency of stools and only mild dehydration but the course of illness was longer in comparison to that of the hospitalized rotavirus diarrhea cases. There is a possibility of spread of infection via fomites, environmental surfaces and most likely mothers.

Occurrence of multi-resistant Salmonella typhimurium infection in a pediatric hospital at Calcutta.

Salmonella typhimurium was isolated from 55 (15.9%) of the 347 hospitalized diarrheal children and 14 (11.1%) of the 126 non-diarrheal controls. All the 98 asymptomatic children attending hospital outpatients were negative. Six (3.7%) of the 162 samples of different categories examined from the hospital were positive for S. typhimurium. Finger washing of one female food handler, feces of two cats of the wards, surface of wash basin, lavatory seat and shelf yielded positive isolations. In vitro antibiotic sensitivity testing showed majority of the strains were resistant against commonly used antimicrobial agents while they were uniformly sensitive to norfloxacin and ciprofloxacin. The present study points to cross-infection by multi-resistant S. typhimurium strains in the hospital wards.

Effectiveness of oral rehydration salt solution (ORS) in reduction of death during cholera epidemic.

An extensive outbreak of acute gastroenteritis involving all age group of patients occurred during July-September, 1978 in the Central district of Manipur state. A total of 4469 cases occurred during the period. 45.7% of diarrhoea cases sampled and 47.6% of water samples collected from rivers were found to be positive for V.cholerae biotype EITor. Case fatality rate in this epidemic was exceptionally low (0.8%) which was attributed to the early domiciliary use of oral rehydration salt solution (ORS) in the affected villages. Utility of ORS in drastic reduction of case fatality rate during any epidemic situation was first of its kind in the Indian scene.

Report of an outbreak of diarrhoeal disease caused by cholera followed by rotavirus in Manipur.

An outbreak of acute diarrhoeal disease between August and October 1985 in 3 districts of Manipur state was investigated amongst 9,29,077 population at risk. The overall attack rate and case fatality rate were 0.2% and 0.9% respectively. Hospital records revealed that 58.8% of cases occurred amongst older children above 5 years of age. V.cholera was isolated from 25.3% of cases sampled. Interestingly, increased frequency in weekly admission of cases amongst children during first two years of life increased in the beginning of October when the original peak of diarrhoeal outbreak was about to decline. The October peak was caused by rotavirus which could be detected from 50.0% of diarrhoeal children in this age group. This possibly reflected beginning of the usual rotavirus diarrhoea season in the locality.