ABSTRACT
Background & objectives: Mycoplasma pneumoniae is the most important and common cause of community-acquired pneumonia (CAP). The conventional detection methods (culture and serology) lack sensitivity. PCR offers a better approach for rapid detection but is prone to carry over contamination during manipulation of amplification products. Quantitative real-time PCR (qRT-PCR) method offers an attractive alternative detection method. In the present study, qRT-PCR, PCR and serology methods were used to detect M. pneumoniae infection in cases of pneumonias and findings compared. Methods: A total of 134 samples consisting of blood (for serology) and respiratory secretions (for PCR and qRT-PCR) from 134 patients were collected. The blood samples were tested for IgG, IgM and IgA using commercially available kits. For standardization of PCR of M. pneumoniae P1 gene was cloned in pGEMTEasy vector. Specific primers and reporter sequence were designed and procured for this fragment. The qRT-PCR assay was performed to prepare the standard curve for M. pneumoniae positive control DNA template and detection in patient samples. Results: Of the 134 patients, 26 (19%) were positive for antibodies against M. pneumoniae. IgG was positive in 14.92 per cent (20) cases, IgM in 4.47 per cent (6) and IgA was positive in 5.22 per cent (7) cases. In the qRT-PCR assay 19 per cent (26) samples were positive. Of the 26 qRT-PCR positive samples, nine could be detected by serology. PCR was positive for 25 samples. An extra sample negative by PCR was detected by qRT-PCR. Thus, real-time PCR assay, PCR and serology in combination could detect M. pneumoniae infection in 43 patients. Interpretation & conclusions: The study shows that 17 patients were detected by serology alone, 17 were detected by qRT-PCR only and nine patients were positive by both serology and real-time PCR. Of the 134 samples tested, 25 were positive by conventional PCR, but qRT-PCR could detect one more sample that was negative by PCR and serology. These results suggest that a combination of two or three methods may be required for reliable identification of CAP due to M. pneumoniae.
ABSTRACT
We report here a case of polyarthritis caused by Mycoplasma pneumoniae in a 30 years old male who initially triggered suspicion of tuberculosis. Synovial fluid subjected to AFB smear, culture and PCR for Mycobacterium tuberculosis along with culture for aerobic and anaerobic bacteria by standard methods were negative. Synovial fluid was found to be positive by PCR for M. pneumoniae amplifying 543 bp fragment of P1 gene, however it could not be grown in culture. Specific IgG immunoglobulins to M. pneumoniae were also detected in synovial fluid as well as serum by ELISA which were further confirmed by IgG immunoblotting showing response to M. pneumoniae proteins specially immunodominant protein P1. The finding that both M. pneumoniae DNA and specific antibodies to M. pneumoniae are present in synovial fluid of the patient suggests that M. pneumoniae play an important role in arthritis. To the best of our knowledge, this is the first PCR confirmed M. pneumoniae infection in synovial fluid from a case of polyarthritis.