Browsing by Author "Somasiri, D.A.D.H."

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Evaluation of a rapid whole blood assay for testing dengue patients at point of care
(Sri Lanka College of Microbiologists, 2004) Sunil-Chandra, N.P.; Karunasekera, E.W.S.; Somasiri, D.A.D.H.; Samarakoon, S.M.R.M.; Jayawardena, K.A.T.M.; Fernando, W.M.D.; Wijesooriya, W.R.P.L.I.; Garcia, M.
INTRODUCTION: Dengue is the most significant mosquito borne viral disease affecting nations from Asia to the Americas. Symptoms associated with dengue infection range in severity. . The presentation of disease is impacted by age, prior exposure to the virus and the infecting strain of virus. The more severe form of the disease (haemorrhagic fever) can lead to mortality are generally associated with Secondary infections. Clinically, the measurement of dengue-specific IgM and elevated IgG, allows for the detection and differentiation of Primary and Secondary dengue infection. This discrimination is particularly important in situations such as outbreaks where the allocation of resources needs to be directed to those at greatest risk. In cities and major regional centers worldwide clinicians have access to traditional serological techniques such as ELISA and HAI that measure IgM and IgG levels. Unfortunately, clinicians in rural and remote areas generally do not have the resources available for this technology. Hence there is high clinical utility in a field diagnostic device which has the ability to rapidly and accurately detect and differentiate dengue infections. OBJECTIVES: To evaluate a novel dengue whole blood assay (PanBio) having the capacity for qualitative detection of both dengue-specific IgM and IgG, and differentiate between primary and secondary dengue with regard to sensitivity and specificity. To meet the demand for testing at the point of care or in the near patient environment, the test was required to have the capacity to detect antibodies in whole blood. DESIGN, SETTING AND METHODS: This assay device was used at the bed site of patients to evaluate its performance. The test is simply performed by adding the specimen to the sample well followed by running buffer to the buffer well, wait 15 minutes and visually reading the results. No additional materials required. 231 hospital inpatients in the Gampaha district of Sri Lanka, using a finger prick drop of blood as the analyte were assessed against PanBio Dengue Capture IgM and IgG ELISA for the period of 6 weeks starting from 10Ih November 2003. The capacity to detect and differentiate presumptive primary and secondary dengue was evaluated. RESULTS: The whole blood dengue cassette was able to detect 151 positive and 80 negative samples where as the ELISA could detect 126 positive samples and 105 negative patients. The detection of IgM and IgG positive samples by the cassette gave a relative sensitivity of 94.5%, specificity of 86% and 87.1% agreement between the assays. The cassette was able to identify 71% of positive samples as primary infections (IgM positive) and 96.7% as secondary infections (IgG positive with or without IgM) compared to ELISA. CONCLUSION: These data indicate that the Whole Blood Dengue Cassette has good utility in the detection of primary and secondary dengue with a very high accuracy in discriminating patients at greatest risk and represents a valuable field based assay to support the clinical evaluation of patients presenting with symptoms suggestive of dengue fever. ACKNOWLEDGEMENTS: PanBio Ltd, Australia for the financial assistance and Directors of Teaching hospital Ragama and Base hospitals of Negombo, Gampaha and Wathupitiwala.
Evidence of leptospira and Hanta virus co-infections amongst patients hospitalised for leptospirosis-like illness
(Sri Lanka College of Microbiologists, 2003) Sunil-Chandra, N.P.; Premaratna, R.; Somasiri, D.A.D.H.; de Silva, H.J.
INTRODUCTION: Hantavirus infection and leptospirosis are zoonoses with similar epidemiology and disease forms. Both infections spread to humans from infected rodents. OBJECTIVES: To assess the frequency and clinical manifestations of hantavirus infection in patients hospitalised with leptospirosis-like illness. METHODS: Two groups of patients admitted with leptospirosis-like illness to the University Medical Unit, Ragama, were investigated for evidence of both hantavirus infection and leptospirosis. Demographic data were obtained prospectively from 39 patients (Group 1) (M:F=34:5, mean age 35 yrs) (1996-1997), and retrospectively from 35 patients (Group 2) (M:F=34:1, mean age 30 yrs) who had been admitted to the unit during the previous year (1995-1996). Paired sera from 31/39 patients in Group 1 were tested for IgM antibodies and a single serum sample from 24/35 patients in Group 2 was tested for IgG antibodies to Hantaan and Puumala serotypes of hantavirus using m-capture ELISA separately. The same panels of sera were also tested for the presence of anti-leptospiral IgM (in Group 1) and IgG (in Group 2) antibodies. RESULTS: In Group 1, 9/31 and 25/31 sera were positive for hantavirus and leptospira IgM antibodies respectively. 5/31 were negative for both antibodies. 8/9 hantavirus IgM positive sera were also positive for leptospira IgM antibodies indicating co-infection. 1/9 showed seroconversion to hantavirus only, and 17/31 showed seroconversion to leptospira only. Based on the reactivity of hantavirus IgM antibody positive sera against recombinant hantavirus neucleocapsid proteins by m-capture ELISA, 5/9 had Puumala-like and 2/9 had Hantaan-like predominant antigenic specificities. The other 2/9 showed specificity to Puumala only. In Group 2, 10/24 and 23/24 sera were positive for hantavirus and leptospira IgG antibodies respectively. 1/24 was negative for both. All 10 hantavirus IgG antibody positive sera were also positive for leptospira IgG antibodies. 7 of 10 had specificity to Puumala, 2 of 10 had predominantly Puumala and 1 had predominantly Hantaan antigen specificity. Male predominance, occupations related to agriculture and farming, and exposure to rodents were risk factors associated with leptospirosis-like illness. Anorexia, nausea, and myalgia were features common to all patients More patients with hantavirus infection or with or without leptospirosis than those with leptospira infections only had hepatic (78% Vs. 17%) and renal (56% Vs. 17%) involvement during the course of their illness. Conclusions: In our study, hantavirus infection or co-infection with leptospirosis occurred in about one third of patients with leptospirosis-like illness admitted to hospital. The majority had hepatic and renal involvement. Three hantavirus serotypes, Puumala, Puumala-like and Hantaan-like, were detected.
A study on the bio-burden of doctors' and other health care workers' hands, stethoscopes and other medical devices in a Sri Lankan set up - Potential risk of nosocomial infections?
(Sri Lanka College of Microbiologists, 2003) Thusharika, M.M.P.; Somasiri, D.A.D.H.; Athukorala, G.I.D.D.A.D.; Sunil-Chandra, N.P.
OBJECTIVE: To assess the potential risk of nosocomial infection DESIGN: Descriptive, prospective controlled study over a period of 17 days in November 2002. SETTING: Special care baby unit, labour room, surgical wards 1 and 2. theatre and the intensive care unit of the Teaching Hospital, Ragama. METHODS: Thirty hand imprints including 13 doctors, 17 other health care workers and 85 swabs from 6 stethescopes and 31 medical equipment were taken randomly. Six health care workers and 3 stethoscopes were included for a control study. Cultures were identified and antibiotic sensitivity tests were performed. RESULTS: 97% (29/30) of hand imprints were contaminated. The main pathogen isolated was Staphylococcus aureus (43%). 60% of Staphylococcus aureus strains were methicillin resistant (MRSA) and 33% of MRS A were also resistant to Vancomycin. Vancomycin resistance needs confirmation. There were Klebsiella spp, E. coli and other coliforms in 27%, Pseudomonas spp in 13% and Candida spp in 3%. 73 % (51/85) of equipment were contaminated. There were Staphylococcus aureus in 29%, E. coli, Klebsiella species and other coliforms in 22%, Pseudomonas species in 13%, arid Candida species in 1%. Of the stethescopes. 33% of bells and diaphragms had Staphylococcus aureus. There was complete elimination of organisms from both hands and stethoscopes of the control following the useof4%hibitane CONCLUSION: This study clearly demonstrates the burden of bacterial contamination among hands of healthcare workers in Sri Lanka.
Transmission of atypical Myeobacteria by a fiberoptic bronchoscopc leading to a pseudo-outbreak of tuberculosis
(Sri Lanka College of Microbiologists, 2003) Somasiri, D.A.D.H.; Wijesinghe, C.K.; Sunil-Chandra, N.P.
INTRODUCTION: Failure to eradicate contamination of bronchoscopes that occur during use may lead to person-to-person transmission of Mycobacterium tuberculosis or pseudo-outbreaks from environmental microbes such as nontuberculous mycobacteria. OBJECTIVE: To determine the rate of detection of Mycobacterium strains from sputum and bronchial wash preparations of patients, and the extent of nosocomial transmission of Mycobacterium strains following bronchoscopy, and to determine whether results of smear examination for acid fast bacilli (AFB) can mislead the diagnosis and management of patients. DESIGN ANDSETTING: 107 sputum and 60 broncho alveolar lavage (BAL) samples received from patients suspected of tuberculosis and microbiological specimens from the fiberoptic bronchoscope at the Teaching Hospital, Ragama from January 2001 to October 20027 . METHODS: All samples were stained for AFB with Ziehl-Neelsen stain. Samples which were positive by the stain were inoculated into the Lowenstein-Jensen medium and Para-nitro benzoic acid (PNB) containing medium for culture. RESULTS: 13 of 107 patients' sputum and 39 of 60 patients' BAL samples and the saline wash specimen of the bronchoscope were positive for AFB stain. Sputum of 12/13, BAL samples of 22/39 patients and the saline wash specimen were cultured, 1/12 sputum and 8/22 BAL and the saline wash specimen yielded a growth of an atypical CONCLUSIONS: This study reveals a pseudo-outbreak of acid fast bacilli amongst patients with respiratory disease due to the transmission of non-tuberculous mycobacteria by a fiberoptic bronchoscope indicating the value of positive AFB in BAL for predicting pulmonary tuberculosis is questionable.