Diagnostic value of Streptococcus pneumoniae autolysin rLytA for community acquired pneumonia / 中华检验医学杂志

ABSTRACT

Objective To obtain the recombinant protein LytA (rLytA) of Streptococcus pneumoniae strain (ATCC49619) through prokaryotic expression system and to investigate their diagnostic value for patients with community acquired pneumonia (CAP).Methods The specific primers were designed according to LytA gene sequence of Streptococcus pneumoniae M66 strain recorded in Genbank.The recombinant plasmid pET32a(+)/LytA was constructed and transformed into BL21(DE3) to express LytA.The expressed protein LytA was purified by electroeluting of bag filter.Serum IgM of anti-LytA accordingly of patients with CAP were detected by ELISA.The results were evaluated by Chi-square test.Results The recombinant protein LytA was expressed and purified successfully with a relative molecular weight of 56 000.The IgM antibodies level of anti-LytA was significantly higher than the healthy control group (P=0.000).Diagnostic sensibility and specificity of LytA-IgM were 27.8% and 100.0%,while sensibility and specificity of sputum culture were 19.4% and 72.2%,respectively.The sensibility of LytA-IgM was equal to sputum culture(χ2=0.693,P=0.405),but the specificity was higher than it(χ2=14.316 P=0.000).Conclusions A rLytA-ELISA assay maybe has clinical value for diagnosis of pneumococcal infections.It is more rapid and objective than the culture method.