Among the least 20 species isolated from human sources, E. faecalis and E. faecium are the most frequent ones accounting for at least 85% of the isolates. Enterococci, as already reported, have exhibited resistance to glycopeptide, vancomycin and teicoplanin, by seven types of respective genes. Van A and Van B are considered the most clinically relevant phenotypes and are usually associated with E. faecalis and E. faecium isolates. Other types of glycopeptide resistance encoded by the Van D, Van E, Van G, and Van L genes Inhibitors,research,lifescience,medical are also reported in E. faecalis.3 In the above-mentioned study, the identifications of E. faecalis and the two glycopeptide resistance genotypes described for enterococci has been based on specific

amplification of fragments intragenic to ddl E. faecalis gene and specific amplification of portions of the Van A and Van B genes, respectively. Three pairs of oligodeoxynucleotides, developed by Dutka-Malen and colleagues,4 to prime the amplifications of these fragments, were used. Inhibitors,research,lifescience,medical They,4 developed a PCR assay that allows simultaneous detection of four glycopeptide resistance genotypes (Van A, Van B, Van C-1, and Van C-2) and identification of the species level of clinically relevant enterococci (Enterococcus faecium, E. faecalis, E. gallinarum, and E. casseliflavus). The amplification of portions of the 16S rRNA

(rrs) gene, present in almost all the bacteria, was included Inhibitors,research,lifescience,medical as an internal PCR control to promote the reliability of the assay.5 According to the Clinical Laboratory Improvement Act (CLIA), to verify a new assay it is critical to statistically determine if the assay performance specifications are acceptable Inhibitors,research,lifescience,medical compared to a defined standard reference method.1 These specifications include analytical sensitivity and specificity, accuracy, precision, and any other characteristics required to test the performance and interpretation of results. The performance of clinical test can be evaluated using clinical

sensitivity and specificity, receiver HIV Integrase inhibitor drugs operating characteristic (ROC) Inhibitors,research,lifescience,medical analysis, and positive predictive and negative predictive values of the tests.6 In the above-mentioned study, the authors Adenosine tried to verify the PCR assay by determining its analytical sensitivity and specificity. The major limitation of the study is that for the determination of analytical specificity, the assay should have been tested with closely-related or genetically similar organisms to assess any cross-reactivity with other organisms. However, only two standard strains of vancomycin-resistant enterococci were used to evaluate the test. Typically, for an analytical sensitivity, one should perform minimum 12 repetitions of each target level (low, middle and high) and one level at least 1 log below the expected limit of detection.6 Therefore, the reported analytical specificity and sensitivity need further studies to be confirmed, and clinical specificity and sensitivity remained to be determined.