Study On Diagnosis Of Neonatal Chlamydia Trachomatis Pneumonia By Ligase Chain Reaction Enzyme Linked Immunoadsorbent Assay

Objectives To investigate the sensitivity, specificity, reliability, speed and objectivity of the good method for diagnosis of Chlamydia trachomatis ( CT ) infection. Compare the two methods of gap-ligase chain reaction(Gap-LCR) and tissue culture.Methods Collected nasopharyngeal swabs of our hospital in-patient and out-patient neonate with pneumonia and inoculated the specimens into the monolayer McCoy cell cultivated with 37C, 5 % CO2. Iodine dyeing to detect the CT. The plasmid gene probes labeled with biotin and digoxin were used to amplify CT plasmid DNA of nasopharyngeal swabs were examined by enzyme-linked immunosorbent assay(ELISA) and polyacrylamide gel electrophoresis (PAGE). The tissue culture(TC) negative and Gap-LCR positive specimens were analysed by major outer membrane protein gene probe polymerase chain reaction(PCR). Both TC and Gap-LCR negative cases were analysed by major outer membrane protein gene probe and plasmid PCR. Then calculated the sensitivity, specificity, positive predicative value(PPV) and negative predicative value(NPV) of both TC and Gap-LCR respectively. Compared the difference of the two methods.Results After having inoculated CT, the McCoy cell could form dark brown inclusion bodies. The standard species of CT were positive by LCR. There were nopositive results for clinical specimens of C psittaci, S.aureus and other bacteria and no CT infectiousMcCoy cell by Gap-LCR. It was suggested that Gap-LCR assay had great specificity.393 pneumonia nasopharyngeal swabs specimens were special. There were 49 positive specimens by "gold standard". There were 37 positive cases by TC, and the positive ratio was 9.4 % . The sensitivity, specificity, PPV, NPV of TC detection nasopharyngeal swab specimens was 75.5 % (37/49), 100 % (344/344), 100% (37/37), 96.6 % (344/356) respectively; The sensitivity, specificity, PPV, NPV of Gap-LCR-PAGE detection nasopharyngeal swab specimens was 91.8% (45/49), 99.7 % (343/344), 97.8% (45/46), 98.8 % (343/347) respectively; The sensitivity, specificity, PPV, NPV of Gap-LCR-ELISA detection nasopharyngeal swabs specimens was 95.9 % (47/49), 99.7 % (343/344), 97.9% (47/48), 99.4 % (343/345) respectively. There was significant difference between tissue culture, Gap-LCR-PAGE, Gap-LCR-ELISA by McNemar Test.(p<0.05)Conclusions LCR assay is a kind of rapid and accurate method to diagnose CT infection, compared with cell culture LCR is simple,sensitive and suitable for clinical application.