用半巢式PCR检测无创性标本诊断卡氏肺孢子虫肺炎的实验研究

目的无创性诊断卡氏肺施子虫肺炎。方法采用一对半引物进行半巢式DHFR－PCR检测实验大鼠无创性标本——支气管液、血清及活检标本——肺及肝脏组织中的卡氏肺孢子虫DNA。结果从59只经病理学检查证实的卡氏肺孢子虫肺炎大鼠中采集到的上述4种标本，卡氏肺孢子虫DNA的半巢式DHFR－PCR检出率分别为72.7％（32／44），37.3％（22／59），94．9％（56／59）和36．4％（8／22），而DHFR－PCR的检出率则仅为25％，13．6％，71．2％和9．1％。12只轻度感染的PCP大鼠的无创性标本中卡氏肺孢子虫DNA的检出率由刚提高至41．7％。正常鼠标本及各种病原体对照的半巢式DHFR－PCR均为阴性。结论用半巢式DHFR－PCR无创性地诊断大鼠卡氏肺孢子虫肺炎具有敏感、特异、省时、省力等优点；本文在血和肝中检出卡氏肺孢子虫DNA，提示在卡氏肺孢子虫肺炎大鼠模型中存在虫血症和肺外卡氏肺孢子虫感染。

THE USE OF A HEMI-NESTED POLYMERASE CHAIN REACTION FOR NON-INVASIVE DIAGNOSING PNEUMOCYSTIS CARINII PNEUMONIA IN RATS

Alm To detect rat-derived Pneumocystis carinii DNA for non-invasive diagnosing Pneumocystis cariniipneumonia (PCP). Metbods Three oligonucleotide primers(P,,P, and P,) specific for encoding the gene of dihydrofolate re-ductase(DHFR) of P. carinii were used in the hem-nested PCR. Results Of 59 immunosuppressed Wistar' rats with PCP asevidenced by patho1ogic changes,the P. carinii DNAs in only 13. 6 % (8/59) of sera, 25 % (1l/44) of tracheal aspirates(TA),71. 2N (42/59) of lung tissue samples and 9. l % (2/22) of liver tissue samples were respectively found by the first amplifica-tion using DHFR-PCR with primers P, and P2. After the second amplification by Hn DHFR-PCR with primers P, and P,,theP. carinii DNAs in 37. 3 % (22/59) of sera, 72. 7 % (32/44) of TA, 94. 9 % (56/59) of lung tissue samples and 36' 4% (8/22) ofliver tissue samples were respectively found. In l2 immunosuppressed rats with P. carinii light infection,the sensitivitg of HnDHFR-PCR on serum and TA samples had respectively increased by 41. 7 % over DHFR-PCR. All of the control samples werenegative to Hn DHFR-PCR. Conclusion The results suggest that the detecting P. carinii DNAs in the TA and serum samplesusing Hn DHFR-PCR is useful for non-invasive diagnosing PCR and there are extrapulmonary P. carinii infection in the im-munosuppressed rats.