Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item The use of serology and PCR in the diagnosis of Mycoplasma pneumoniae(Sri Lanka College of Microbiologists, 2010) Wijesooriya, W.R.P.L.I.; Kok, T.W.; Perera, J.; Thilakarathna, Y.; Sunil-Chandra, N.P.INTRODUCTION: M. pneumoniae is the causative agent of primary atypical pneumonia. Patients mount IgM and IgG antibody responses, which are useful diagnostic markers. Tests for specific DNA by polymerase chain reaction (PCR) in respiratory samples offer rapid and highly sensitive detection for M. pneumoniae diagnosis. AIM: To determine the relationship between serology and PCR in the diagnosis of M. pneumoniae inpatients with respiratory tract infections and a control group. METHODOLOGY: Paired sera from 418 adult patients were enrolled (pneumonia - 97, acute bronchitis -183, acute pharyngitis -138). The control group consisted of 87 paired sera from patients without acute respiratory infections. Isotype specific (IgM, IgG) antibodies were tested by M. pneumoniae specific ELISA (IBL-Hamburg-Germany). PCR for M. pneumoniae DNA was done in respiratory samples of serologically positive and age and gender matched serologically negative patients. RESULTS: M. pneumoniae specific IgG was seen in 9.3% (9/97), 5.4% (10/183) and 1.5% (2/138) in patients with pneumonia, acute bronchitis and pharyngitis respectively. IgM was seen in 4.1 % (4/97) and 2.1 % (2/183) and 0% (0/138) respectively. Both IgM and IgG were observed only in patients with pneumonia (2.1% (2/97)). M. pneumoniae DNA was detected in 52% (13/25) of serology confirmed and 15% (4/26) of serology negative cases. CONCLUSION: M. pneumoniae specific DNA was detected in both serologically positive and negative cases. These discordant results showed that with M. pneumoniae infection, both serology and PCR tests should be performed to maximize diagnosis.Item Reliability of cold agglutinin test (CAT) for the detection of patients with Mycoplasma pneumoniae pneumonia in hospitalized patients.(Sri Lankan Society for Microbiology, 2016) Wijesooriya, W.R.P.L.I.; Suni-Chandra, N.P.; Perera, J.INTRODUCTION: M. pneumoniae is one of the causative agents of primary atypical pneumonia. This infection causes 20-40% of community acquired pneumonia and is associated with an array of extra-pulmonary manifestations. There is a need for a rapid diagnostic test in order to prescribe prompt and appropriate antibiotic therapy. Even though isotype specific antibody testing provides definitive diagnosis, paired sera testing does not help in real time diagnosis. Cold agglutinins detectable by the Cold Agglutination Test (CAT) appear and disappear early in infection compared to long lasting specific antibodies that are detectable by specific immunoassays. Although there are some reports suggesting CAT is unreliable, it is being often used to diagnose M. pneumoniae pneumonia in Sri Lankan clinical settings. The aim of the current study was to evaluate the use of CAT as a bed-side screening test for early diagnosis of M. pneumoniae pneumonia compared to ELISA for detection of specific antibodies in the Sri Lankan context. METHODS: Ninety seven clinically and radiologically confirmed patients with pneumonia were enrolled in the study. CAT was performed on acute stage sera. A CAT titer ≥1/32 was considered as positive. Isotype specific M. pneumoniae ELISA with paired sera was compared with CAT results. RESULTS: Mycoplasma pneumonia was confirmed in 15 of the 97 patients in the study using Mycoplasma specific IgM and 4 fold rise in titre. Of these, 3 were positive by the CAT. The sensitivity and specificity of the CAT compared to IgM/4fold rise in IgG detection were 20% (3/15) and 81.7% (67/82) respectively. Negative and positive predictive values of the CAT compared to ELISA were 84.8% (67/79) and 16.7% (3/18) respectively. CONCLUSION: CAT is not a reliable screening test compared to specific antibody detection by isotype ELISA for the detection of M. pneumoniae pneumonia due to its low sensitivity and positive predictive values.