Rapid identification of Mycobacterium tuberculosis complex on urine samples by Gen-Probe amplification test

Evaluation of reverse transcription loop-mediated isothermal amplification in conjunction with ELISA-hybridization assay for molecular detection of Mycobacterium tuberculosis

Traditional culture, followed by a panel of biochemical tests for the diagnosis of tuberculosis (TB), is time-consuming, and rapid identification of Mycobacterium tuberculosis is crucial for the early administration of appropriate therapy. In this study, the reverse transcription loop-mediated isothermal amplification combined with enzyme-linked immunosorbent hybridization (RT-LAMP-ELISA-hybridization) assay has been designed for the rapid detection of 16S rRNA in clinical isolates of M. tuberculosis. This assay reproducibly detected a single copy, as opposed to 2000 copies of MTB 16S rRNA detected by conventional gel electrophoresis. Among the 150 specimens of sputum analysed, RT-LAMP-ELISA-hybridization assay had a sensitivity of 94.1% in the culture method, compared to the Amplified M. tuberculosis Direct Test (AMTD), 91.1% and the 88.2% sensitivity of acid-fast staining. Furthermore, RT-LAMP-ELISA-hybridization assay is more cost-effective when compared to the real-time TaqMan RT-PCR and AMTD assays. In conclusion, our results suggest that the RT-LAMP-ELISA-hybridization assay is a highly sensitive, low cost diagnostic tool useful for the rapid and accurate direct diagnosis of sputum specimens, and is suitable for routine clinical use.

Laboratory diagnosis of urinary tract infections in adult patients

Urinary tract infections (UTIs) are among the most common bacterial infections and account for a significant part of the workload in clinical microbiology laboratories. Enteric bacteria (in particular, Escherichia coli) remain the most frequent cause of UTIs, although the distribution of pathogens that cause UTIs is changing. More important is the increase in resistance to some antimicrobial agents, particularly the resistance to trimethoprim-sulfamethoxazole seen in E. coli. Physicians distinguish UTIs from other diseases that have similar clinical presentations with use of a small number of tests, none of which, if used individually, have adequate sensitivity and specificity. Among the diagnostic tests, urinalysis is useful mainly for excluding bacteriuria. Urine culture may not be necessary as part of the evaluation of outpatients with uncomplicated UTIs, but it is necessary for outpatients who have recurrent UTIs, experience treatment failures, or have complicated UTIs, as well as for inpatients who develop UTIs.