用PCR诊断不同虫荷量的大鼠卡氏肺孢子虫肺炎的价值

THE VALUE OF PCR FOR DIAGNOSING PCP UNDER DIFFERENT BURDEN OF PNEUMOCYSTIS CARINII IN RAT MODELS

目的 评价在不同虫荷量条件下用 PCR诊断大鼠卡氏肺孢子虫肺炎 (PCP)的价值。 方法 将 PCP大鼠随机分为药物治疗组及未治疗组 ,测定其肺虫荷量 ,收集其支气管灌洗液 (BAL F)和血清标本 ,用 PCR和半套式 (Sn) PCR检测标本中的卡氏肺孢子虫基因 ,比较 PCR和环六亚甲基四胺银 (GMS)染色结果 ,及与病鼠肺虫荷量的关系。 结果 虫荷量高的未治疗组病鼠的 BAL F标本 PCR、Sn PCR及 GMS染色阳性率分别为 10 0 %、10 0 %和 92 .6 % ,差异无显著性 (P>0 .0 5 ) ;而虫荷量低的治疗组的 PCR(88.1% )、Sn PCR(94 .9% )阳性率均显著高于 GMS染色镜检阳性率 (30 .5 % ) (P<0 .0 5 )。肺虫荷量 >5 0 0个 /mg肺的 PCP大鼠 ,血清 PCR阳性率显著高于≤ 5 0 0者 (分别为 4 2 .9%和 1.7% )。 结论 PCR可用于虫株负荷量较低时的 PCP诊断 ,对判断 PCP病情及疗效考核亦有一定的帮助。

Objective To evaluate the value of PCR for diagnosing Pneumocystis carinii pneumonia(PCP) under different burden of P. carinii in rat models. Methods PCP model rats were randomly divided into two groups: therapy group and untherapy group. It was assayed the burden of P. carinii of the experimental rats. PCR and Sn PCR were used to detect P. carinii DNA in the specimens of bronchoalveolar lavage liquid (BALF) and serum collected from the PCP rats. The results of PCR were compared with that of GMS stain in BALF specimens in each group. And the results of serum PCR were also compared with the burden of P. carinii. Results In the untherapy group that of burdens of P. carinii were high, the positive rates of PCR, Sn PCR and GMS stain were 100%, 100% and 92.6% in the BALF specimen respectively (P>0.05). But in the therapy group that of burdens of P. carinii were low, the positive rates of PCR (88.1%) and Sn PCR (94.9%) in the BALF specimens were much higher than that of GMS stain (30.3%)(P< 0.05 ). Of the serum specimens collected from the PCP rats whose burden of P. carinii were≤500 cysts/mg of lung, only 1.7% showed PCR positive, and were much lower than that(42.9%)of PCP rats whose burden of P. carinii were >500 cysts/mg of lung (P< 0.05 ). Conclusion PCR and Sn PCR may detect P. carinii DNA in BALF specimen of the rats whose burden of P. carinii were very low, so they may play a role in diagnosing early PCP, and estimating the efficiency of drugs.