Evaluation of PCR on Bronchoalveolar Lavage Fluid for Diagnosis of Invasive Aspergillosis: A Bivariate Metaanalysis and Systematic Review

BACKGROUND: Nucleic acid detection by polymerase chain reaction (PCR) is emerging as a sensitive and rapid diagnostic tool. PCR assays on serum have the potential to be a practical diagnostic tool. However, PCR on bronchoalveolar lavage fluid (BALF) has not been well established. We performed a systematic review of published studies to evaluate the diagnostic accuracy of PCR assays on BALF for invasive aspergillosis (IA). METHODS: Relevant published studies were shortlisted to evaluate the quality of their methodologies. A bivariate regression approach was used to calculate pooled values of the method sensitivity, specificity, and positive and negative likelihood ratios. Hierarchical summary receiver operating characteristic curves were used to summarize overall performance. We calculated the post-test probability to evaluate clinical usefulness. Potential heterogeneity among studies was explored by subgroup analyses. RESULTS: Seventeen studies comprising 1191 at-risk patients were selected. The summary estimates of the BALF-PCR assay for proven and probable IA were as follows: sensitivity, 0.91 (95% confidence interval (CI), 0.79-0.96); specificity, 0.92 (95% CI, 0.87-0.96); positive likelihood ratio, 11.90 (95% CI, 6.80-20.80); and negative likelihood ratio, 0.10 (95% CI, 0.04-0.24). Subgroup analyses showed that the performance of the PCR assay was influenced by PCR assay methodology, primer design and the methods of cell wall disruption and DNA extraction. CONCLUSIONS: PCR assay on BALF is highly accurate for diagnosing IA in immunocompromised patients and is likely to be a useful diagnostic tool. However, further efforts towards devising a standard protocol are needed to enable formal validation of BALF-PCR

Purification of the DNA-dependent RNA polymerase from the myxobacterium Stigmatella aurantiaca.

The DNA-dependent RNA polymerase (EC 2.7.7.6) of the myxobacterium Stigmatella aurantiaca has been purified. It shows three main polypeptide bands with apparent molecular weights of 146,000, 105,000, and 40,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. beta and beta' subunits of the S. aurantiaca polymerase were shown to migrate in the 146,000-molecular-weight polypeptide band and the main sigma factor was shown to migrate in the 105,000-molecular-weight band by using heterologous antisera

Purification and characterization of SP21, a development-specific protein of the myxobacterium Stigmatella aurantiaca.

Stigmatella aurantiaca is a gram-negative bacterium with a complex life cycle, including cellular aggregation resulting in the formation of a characteristic three-dimensional structure, the so-called fruiting body. During fruiting and upon chemical induction of sporulation, a major development-specific protein, SP21, is synthesized. SP21 was purified to homogeneity from the membranous fraction of chemically induced spores. Expression of SP21 was studied with an antiserum raised against the purified protein