Prospective comparison of eubacterial PCR and measurement of procalcitonin levels with blood culture for diagnosing septicemia in intensive care unit patients.

Rapid identification of infection has a major impact on the clinical course, management, and outcome of critically ill intensive care unit (ICU) patients. We compared the results of PCR and procalcitonin with blood culture for ICU patients suspected of having septicemia. Ninety patients (60 patients meeting the criteria for sepsis and 30 patients not meeting the criteria for sepsis) were evaluated. Compared with blood culture as the gold standard, the sensitivity, specificity, and positive and negative predictive values for PCR were 100%, 43.33%, 46.87%, and 100%, respectively, and for procalcitonin were 100%, 61.66%, 56.6%, and 100%, respectively. The average times required to produce a final result were as follows: PCR, 10 h; blood culture, 33 h; procalcitonin, 45 min. Both PCR and procalcitonin may be useful as rapid tests for detecting septicemia but compared with blood cultures lacked specificity.

An improved method of elimination of DNA from PCR reagents.

OBJECTIVE: The presence of exogenous DNA in commercially available polymerase chain reaction (PCR) reagent preparations is a serious problem when amplifying conserved regions of bacteria. The preferred and currently in-use method of decontamination using 8-methoxypsoralen (8-MOP) and UVA requires re-standardization of decontamination with increasing concentrations of 8-MOP and UVA irradiation timings, if the DNA load of reagents is high due to lot-to-lot differences. The objective of this study was to develop a decontamination method, which would (i) work at the minimum reported concentration of 8-MOP and UVA irridation timings; and (ii) take care of inter-batch DNA-load variability of reagents. MATERIALS AND METHODS: The improved method described here was formulated after studying the exact molecular mechanism of action of 8-MOP with DNA. The successful working of the method was experimentally proven and validated with 6-7 new batches of PCR reagents. The sensitivity of eubacterial PCR, after using the new method of decontamination, to be used clinically was checked with both the spiked specimens and the actual clinical specimens. RESULTS AND DISCUSSION: The new method was found to work at the same starting parameters of 8-MOP and UVA in such situations. The increased efficiency of this method was found to be due to the synergistic effect of both the selective treatment of Taq DNA polymerase and the split-irradiation approach.

Comparing serology, antigenemia assay and polymerase chain reaction for the diagnosis of cytomegalovirus infection in renal transplant patients.

BACKGROUND: Cytomegalovirus (CMV) disease is responsible for significant morbidity and mortality following renal transplantation. Currently serology is the only method widely available in our country. Newer methods like early CMV pp65 antigenemia assay and CMV DNA amplification can diagnose CMV disease in its very early period. AIM: The aim of our study was to compare serologic method with antigenemia assay and CMV DNA amplification to diagnose CMV. METHODS: Seventy-three renal transplant recipients (from 7 centres) with clinical suspicion of CMV disease were studied prospectively. The diagnosis of CMV infection was suspected on the basis of fever and leucopenia. RESULT AND DISCUSSION: Three tests were done in all 73 patients and in 22 healthy subjects (control group). The sensitivity and specificity of serological test (CMV IgM) was 72.97 and 62.06%; of antigenemia assay was 89.18 and 100% and of PCR was 100 and 72.41%. CONCLUSION: Antigenemia assay is a sensitive and specific test for early and rapid diagnosis of CMV infection. Qualitative PCR is a sensitive marker but has low specificity.