First do no harm: making oral rehydration solution safer in a cholera epidemic.
(17/1654)
Oral rehydration solution (ORS) is lifesaving therapy for cholera and pediatric diarrhea. During a cholera epidemic in Guinea-Bissau, we evaluated the microbiologic quality of ORS prepared at a hospital and tested a simple intervention using special vessels for disinfecting tap water with bleach and for preparing, storing, and dispensing ORS. Few coliform bacteria and Escherichia coli were recovered from tap water; however, pre-intervention ORS contained numerous bacteria including E. coli and toxigenic Vibrio cholerae O1. In contrast, ORS samples from intervention vessels had few or no coliform bacteria, no E. coli, and no V. cholerae. Mean pre-intervention counts of coliform bacteria (3.4 x 10(7) colony-forming units [cfu]/100 ml) and E. coli (6.2 x 10(3) cfu) decreased significantly during the intervention period to 3.6 x 10(2) cfu and 0 cfu, respectively (P < 0.001). This simple system using bleach disinfectant and special storage vessels prevents bacterial contamination of ORS and reduces the risk of nosocomial transmission of cholera and other enteric pathogens. (+info)
Efficacy of orally administered oxolinic acid and Vetoquinol, an oxolinic acid ester, for the treatment of furunculosis in Atlantic salmon Salmo salar held in seawater.
(18/1654)
This study was performed to determine the efficacy of orally administered oxolinic acid and Vetoquinol, an oxolinic acid ester, in the treatment of experimental induced furunculosis in Atlantic salmon Salmo salar held in seawater. Two strains of the causative bacterium Aeromonas salmonicida subsp. salmonicida, 1 sensitive (VI-88/09/03175) and 1 resistant (3475/90) to oxolinic acid, were used. In 2 trials, cohabitational challenges were performed by introducing 8 fish challenged in advance by an intraperitoneal injection of 2.2 x 10(4) colony forming units of strain 3475/90 (Trial 1) or strain VI-88/09/03175 (Trial 2) to 10 aquaria each containing 40 healthy fish. The treatment groups in both trials consisted of 4 groups receiving either oxolinic acid (2 groups) or Vetoquinol (2 groups) and 1 control group. An unchallenged, unmedicated group was used to determine the natural mortality in the population. The recommended therapeutic dose of 25 mg oxolinic acid kg-1 fish at Days 1, 2, 4, 6, 8 and 10 following initiation of treatment was used. Oral medication initiated at Day 10 (Trial 1) or Day 11 (Trial 2) following challenge significantly (p < 0.05) lowered the specific mortality in all drug-treated groups compared to the untreated control groups. Mortality in Vetoquinol-treated groups was significantly (p < 0.05) lower than in oxolinic acid-treated groups in Trial 1 whereas no significant (p < 0.05) difference in survival rate was found between the medicated groups in Trial 2. (+info)
A preliminary investigation on the chemical composition of the cell surface of five enteropathogenic Escherichia coli serotypes.
(19/1654)
The cell surfaces of five enteropathogenic Escherichia coli serotypes (O111:H2; O111:H12; O125:H9; O119:H6; O26:H11) were assayed by chemical methods, lectin agglutination tests and spectroscopy associated to transmission electron microscopy. Results of lectin agglutination assays showed that all strains reacted with mannosebinding lectins. Strains belonging to serotype O125:H9 also agglutinated with lectins which recognize galactose and Nacetylgalactosamine residues. The bacterial cells were treated with 0.01M phosphate buffered saline (pH 7.0) at 100 degree C for 2 hr and the extracts were submitted to precipitation and fractionated by Cetavlon. Phosphate, total sugar and protein contents were determined. Gas liquid chomatography-mass spectrometry analysis of alditol acetates showed the presence of galactose, mannose, fucose, glucose and traces of ribose. Spectroscopic analysis of intact cells showed the presence of a capsule-like structure which was not totally preserved after extraction. Some cells were still surrounded by an amorphous capsular-like material after polysaccharide extraction. (+info)
Value of a single-tube widal test in diagnosis of typhoid fever in Vietnam.
(20/1654)
The diagnostic value of an acute-phase single-tube Widal test for suspected typhoid fever was evaluated with 2,000 Vietnamese patients admitted to an infectious disease referral hospital between 1993 and 1998. Test patients had suspected typhoid fever and a blood culture positive for Salmonella typhi (n= 1,400) or Salmonella paratyphi A (n = 45). Control patients had a febrile illness for which another cause was confirmed (malaria [n = 103], dengue [n = 76], or bacteremia due to another microorganism [n = 156] or tetanus (n = 265). An O-agglutinin titer of >/=100 was found in 18% of the febrile controls and 7% of the tetanus patients. Corresponding values for H agglutinins were 8 and 1%, respectively. The O-agglutinin titer was >/=100 in 83% of the blood culture-positive typhoid fever cases, and the H-agglutinin titer was >/=100 in 67%. The disease prevalence in investigated patients in this hospital was 30.8% (95% confidence interval, 26.8 to 35.1%); at this prevalence, an elevated level of H agglutinins gave better positive predictive values for typhoid fever than did O agglutinins. With a cutoff titer of >/=200 for O agglutinin or >/=100 for H agglutinin, the Widal test would diagnose correctly 74% of the blood culture-positive cases of typhoid fever. However, 14% of the positive results would be false-positive, and 10% of the negative results would be false-negative. The Widal test can be helpful in the laboratory diagnosis of typhoid fever in Vietnam if interpreted with care. (+info)
International multicenter evaluation of the clinical utility of a dipstick assay for detection of Leptospira-specific immunoglobulin M antibodies in human serum specimens.
(21/1654)
We performed a multicenter evaluation of a robust and easily performed dipstick assay for the serodiagnosis of human leptospirosis. The assay is aimed at the detection of Leptospira-specific immunoglobulin M (IgM) antibodies. The study involved 2,665 serum samples collected from 2,057 patients with suspected leptospirosis in 12 countries on five continents with different levels of endemicity and different surveillance systems. The patients were grouped as laboratory-confirmed leptospirosis case patients and noncase patients based on the results of culturing and the microscopic agglutination test. Paired samples from 27.7% of the subjects were tested. Of the 485 case patients, 87.4% had a positive dipstick result for one or more samples. Of the 1,513 noncase patients, only 7.2% had a positive result. Whereas most (88.4%) of the positive samples from the case patients showed moderate to strong (2+ to 4+) staining in the dipstick assay, most (68.1%) of the positive samples from the noncase patients showed weak (1+) staining. The sensitivity of the dipstick assay increased from 60.1% for acute-phase serum samples to 87.4% for convalescent-phase samples. The specificities for these two groups of samples were 94.1 and 92.7%, respectively. The dipstick assay detected a broad variety of serogroups. The results of the dipstick assay were concordant (observed agreement, 93.2%; kappa value, 0.76) with the results of an enzyme-linked immunosorbent assay for the detection of specific IgM antibodies, a test which is often used in the laboratory diagnosis of current or recent leptospirosis. This study demonstrated that this easily performed dipstick assay is a valuable and useful test for the quick screening for leptospirosis; has a wide applicability in different countries with different degrees of endemicity; can be used at all levels of the health care system, including the field; and will be useful for detecting and monitoring outbreaks of leptospirosis. (+info)
Leptospiral infection among primitive tribes of Andaman and Nicobar Islands.
(22/1654)
The Andaman islands were known to be endemic for leptospirosis during the early part of the century. Later, for about six decades no information about the status of the disease in these islands was available. In the late 1980s leptospirosis reappeared among the settler population and several outbreaks have been reported with high case fatality rates. Besides settlers, these islands are the home of six primitive tribes of which two are still hostile. These tribes have ample exposure to environment conducive for transmission of leptospirosis. Since no information about the level of endemicity of the disease among the tribes is available, a seroprevalence study was carried out among all the accessible tribes of the islands. A total of 1557 serum samples from four of the tribes were collected and examined for presence of antileptospiral antibodies using Microscopic Agglutination Test (MAT) employing 10 serogroups as antigens. An overall seropositivity rate of 191% was observed with the highest rate of 53.5% among the Shompens. The seropositivity rates in the other tribes were 16.4% among Nicobarese, 222% among the Onges and 14.8% among the Great Andamanese. All of the tribes except the Onges showed a similar pattern of change in the seroprevalence rates with age. The prevalence rates were rising from low values among children to reach a peak in those aged 2140 years and then declined. Among Onges the seroprevalence rates continued to rise beyond 40 years. In all the tribes, seroprevalence rates were found to be significantly higher among the males. The commonest serogroups encountered were Australis followed by Grippotyphosa, Icterohaemorrhagiae, Pomona and Canicola. (+info)
Co-agglutination test for the detection of circulating antigen in amebic liver abscess.
(23/1654)
We report here a simple and economical slide agglutination test, the co-agglutination (Co-A) test, for the detection of circulating amebic antigen in sera for the diagnosis of amebic liver abscess. Fifty serum specimens from cases of amebic liver abscess, 25 from other individuals with parasitic and miscellaneous infections, and 25 from healthy controls were tested for the presence of serum antigen by the Co-A test. Forty-five (90%) amebic liver abscess sera were found to be amebic-antigen positive by the Co-A test. None of 25 sera from healthy controls were positive for the antigen. However, false-positive results were seen with two sera from those with other parasitic and miscellaneous infection controls. These results show that the Co-A test can be used as a sensitive and specific rapid slide agglutination test for the detection of amebic antigen in the sera for diagnosis of cases of amebic liver abscess in a routine parasitology laboratory. (+info)
Cross-reaction between a strain of Vibrio mimicus and V. cholerae O139 Bengal.
(24/1654)
Of 200 isolates of Vibrio mimicus screened, one from water (N-57) agglutinated with V. cholerae O139 polyclonal antiserum (absorbed with a rough strain of V. cholerae only) and not with O139 polyclonal diagnostic antiserum (absorbed with the rough strain and V. cholerae O22 and O155). The antigenic relationship between V. cholerae 0139 and N-57 is of a,b-a,c type, where a is the common antigenic epitope and b and c are unique epitopes. Strain N-57 was assigned to a new serogroup of V. cholerae O194. It gave negative results in a monoclonal antibody-based rapid test and a PCR test specific for V. cholerae O139. It did not possess the ctx gene or produce cholera toxin. Antiserum to strain N-57 cross-protected infant mice against cholera on challenge with V. cholerae O139. Structural studies of the surface polysaccharides and studies of the rfb genes will shed more light on the extent of relatedness between V. mimicus N-57 and V. cholerae O139. (+info)