Browsing by Author "Thilakarathna, Y."

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Analysis of Mycoplasma pneumoniae IgG response in patients with respiratory tract infections
(Research Symposium 2010 - Faculty of Graduate Studies, University of Kelaniya, 2010) Wijesooriya, W.R.P.L.I.; Kok, T.W.; Perera, J.; Thilakarathna, Y.
Introduction M. pneumoniae is the causative agent of primary atypical pneumonia. Patients mount IgM and IgG antibody responses against this infection. However, IgM antibodies are not always produced in adults upon reinfection. Therefore, diagnosis of M. pneumoniae infection in adults relies on specific IgG response which increases slowly during the course of illness. Most clinicians receive a single serum sample for serology tests, as paired sera testing will not be useful for management due to time delay or patients may not provide a convalescent-phase sample. Aim Analysis of the M. pneumoniae specific IgG response in paired-sera of patients with respiratory tract infections. Methodology A prospective clinical study was carried out involving 418 adult patients in Colombo North Teaching Hospital, Ragama and chest hospital, Welisara (Pneumonia-97, acute bronchitis-183, pharyngitis-138). M. pneumoniae specific IgG was tested and analyzed in paired sera using ELISA kits (IBLHamburg-Germany). Results 27 patients showed positive IgG antibody titer in acute, convalescent or both serum samples. In these 27 samples, seven were positive in acute-serum samples and negative in convalescent-samples. Thirteen were positive at convalescent-sampling but negative at acute-sampling. Seven were positive in both acute and convalescent samples. Discussion Only 25.9% (7/27) of the cases would be diagnosed correctly using paired sera. 48.2% (13/27) would be negatively misdiagnosed 25.9% (7/27) would be positively misdiagnosed by testing acute sample alone. Paired-serum samples were essential to confirm the diagnosis of 74.1% (20/27) of patients with suspected M. pneumoniae infection. Conclusion Paired-serum samples are mandatory in the diagnosis M. pneumoniae infection based on IgG response.
Detection of M. pneumoniae DNA and specific antibodies in relation to duration of illness
(Sri Lanka College of Microbiologists, 2009) 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 provide useful diagnostic markers. Tests for specific antibodies-and DMA amplification by poiymerase chain reaction (PCR) in respiratory samples are now widely used for this infection. The timing of specimen collection is the one most important component to influence test sensitivity, amongst other test parameters. AIM: To determine optimum sampling time for detection of M. pneumoniae specific IgG/IgM antibodies and DNA by PCR. DESIGN, SETTING AND METHOD: A prospective clinical study was carried out involving 418 adult patients in Colombo North Teaching Hospital, Ragama and Chest Hospital, Welisara. (Pneumonia -97, acute bronchitis - 183, pharyngitis - 138). M. pneumoniae specific IgG and IgM were tested in paired sera using ELISA kits (IBL-Hamburg-Germany). PCRfor M. pneumoniae DNA was done for serologically positive and serologically negative patients. Each positive result was analysed in relation to duration of illness. RESULTS: IgM was detected in 37.5% (3/8) of patients on days 1-10 , 37.5% (3/8) on, days 11-20 , 12.5% (1/8) days 21 -30 and 12.5% (1/8) days 31 -40 post onset of illness (poi). IgG was detected in 48% (11/23) of patients on days 11-20, 22% (5/23) days 21-30 poi. M. pneumoniae DNA was detected in 94% (16/17) during the first 15 days of illness. Three seronegative patients (3/4, 75%) were negative for M. pneumoniae DNA >15 days poi. CONCLUSION: IgM response, higher during the first 20 days of illness than IgG which was detected during days 11-20, post onset of illness. M. pneumoniae DNA was detected within the first two weeks of illness.
Paired sera IgG test detects more Mycoplasma pneumonias infections than the single IgM test
(Sri Lanka College of Microbiologists, 2009) 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 an IgM and IgG antibody response, which are useful diagnostic markers. The single serum test for IgM specific antibodies may be attractive for rapid laboratory diagnosis, due to delays or non-provision of the convalescent phase serum sample by patients. IgM antibodies are not always produced in adults upon reinfection. AIMS: To evaluate the diagnostic value of paired serum IgG testing compared to single serum IgM for diagnosis of M. pneumoniae infection. DESIGN, SETTING AND METHOD: A prospective clinical study was done involving 418 adult patients in Colombo North Teaching Hospital, Ragama and Chest Hospital, Welisara. {Pneumonia-97, acute bronchitis-183, pharyngitis-138). Control group-87 adults with no acute respiratory infections. M. pneumoniae specific IgG and IgM were tested in paired sera (taken 2-3 weeks apart) using an ELISA kit (IBL-Hamburg-Germany). RESULTS: Patients with >12 U/ml IgM response or IgG sero-conversion were considered positive for this infection. IgM response was detected in 27% (6/22) (4 - pneumonia, 2 - acute bronchitis) of the study population. IgG sero-conversion was detected in 64% (14/22) (9 - pneumonia, 10 - acute bronchitis, 2 - pharyngitis) and 9% (2/22) (2 -pneumonia) by both antibody types. In this study population, IgM specific antibodies were detected in 36% (8/22).There were no IgG responders in the control group but 2% (2/87) showed positive IgM response. CONCLUSION: Specific IgG testing with paired serum samples detect more cases of M. pneumoniae infection than the use of a single serum IgM test.
Predisposing factors associated with Mycoplasma pneumoniae respiratory tract infections
(Research Symposium 2010 - Faculty of Graduate Studies, University of Kelaniya, 2010) Wijesooriya, W.R.P.L.I.; Kok, T.W.; Perera, J.; Thilakarathna, Y.
Introduction Lower respiratory tract infections account for ~10% of worldwide burden of morbidity and mortality. Pneumonia is the 9th leading cause of hospital mortality in Sri Lanka and atypical pathogens account for 1/5th of the cases. M. pneumoniae is the predominant (50%) atypical pathogen. Knowing predisposing factors strengthen the modes of prevention. Objective Determination of predisposing-factors associated with M. pneumoniae respiratory infections in Sri Lanka. Methodology A prospective clinical study was done involving 416 adult-patients in Colombo-North Teaching-Hospital, Ragama and chest-hospital, Welisara (Pneumonia-97, acute-bronchitis-182, pharyngitis-137). M. pneumoniae specific IgG and IgM were tested in paired-sera using commercial-ELISA. Patient-interviewed-questionnaire was used to obtain data on predisposing factors and evaluated in serologically-positive and serologically-negative groups. The level of significance was considered as p < 0.05. Results There was no significant difference observed in relation to age (p-value-0.28, 0.76 and 0.2in pneumonia, bronchitis, pharyngitis respectively), gender, number of individuals/room (sleeping area) (p=0.82), having respiratory tract infections in close contacts (p=0.15), malignancies or past history of asthma (p>0.05 in both groups) with M. pneumoniae infection. However, there was significant association between M. pneumoniae pneumonia and diabetes mellitus (p<0.05). Discussion There was no specific age group detected to have M. pneumoniae infections which predominantly occur in childhood or significant gender predominance seen as with previous studies. The present study was not carried out in a setting with closed population to have significant infection amongst closed contacts. The significant association between M.pneumoniae infection and having diabetes mellitus would need further studies. Conclusion There were no identifiable strong factors predisposing to M. pneumoniae infection except diabetes mellitus.
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.