[Comparision of Different Detection Methods for Blood Flow Infection with Cryptococcus Neoformans].

Objective: To compare the sensitivity and specificity of real-time fluorescent quanttative PCR(FQ-PCR), blood culture and serum capsular antigen test for the detection of blood flow infection with cryptococcus reoformans, so as to provide the experimental evidence for use of FQ-PCR to detect the blood flow infection with cryptococcus neoformans.

Methods: Sixty male Sprague-Dawley (SD) rats were randomly divided into group A (immune suppression plus infection), group B (immune normal plus infection), group C (immune suppression plus non infection) and group D (normal control). The rats in group A were injected intraperitoneally with cyclophosphamide at D1 of experiment and were injected with suspension of cryptococcus neoformans by tail vein at D4 of experiment; the rats in group B were injected intraperitoneally with saline at D1 and were injected with suspension of cryprococcus neoformans by tail vein at D4; the rats in group C were injected intraperitoneally with cyclophosphamide at D1 and were injected with saline by tail vein at D4; the rats in group D were injected intaperitoneally with saline at D1 and were injected with saline by tail vein at D4.At D 4 after successful extablishment of rat model with infection, the blood samples were collected from ocular veneous plexus at 0, 6, 12, 24, 48 and 72 hours by parity number respectively, then the plasma was extracted, and the blood samples infected at different time were detected by FQ-PCR, and at the same time, the blood culture and serum capsular antigen test were performed. The detected results obtained from above-mentioned 3 kinds of detection methods were compared.

Results: The FQ-PCR detection of cryptococcus neoformoms showed that the positive rate detected after 12 hours in A group significantly increased (P<0.05), as compared with B, C and D groups. For the blood samples, the positive rate detected by FQ-PCR was significantly higher than that detected by the blood culture and serum capsular antigen test, moreover the detected results could be quantified, and difference was statistically significant (P<0.05).

Conclusion: The FQ-PCR system for detection of cryptococcus neoformant can detect the pathogens in blood of infected rats, and its sensitivity is superior to the blood culture and serum capsular antigen test; the FQ-PCR can detect the pathogens in blood of infected rats much more early, as compared with the blood culture and serum capsular antigen test.