A luciferase-based assay for rapid assessment of drug activity against Mycobacterium tuberculosis including monitoring of macrophage viability.

The intracellular (IC) effect of drugs against Mycobacterium tuberculosis (Mtb) is not well established but increasingly important to consider when combining current and future multidrug regimens into the best possible treatment strategies. For this purpose, we developed an IC model based on a genetically modified Mtb H37Rv strain, expressing the Vibrio harvei luciferase (H37Rv-lux) infecting the human macrophage like cell line THP-1. Cells were infected at a low multiplicity of infection (1:1) and subsequently exposed to isoniazid (INH), ethambutol (EMB), amikacin (AMI) or levofloxacin (LEV) for 5days in a 96-well format.

Rapid identification of pneumococci, enterococci, beta-haemolytic streptococci and S. aureus from positive blood cultures enabling early reports.

Background: The aim of this study was to evaluate diagnostic tests in order to introduce a diagnostic strategy to identify the most common gram-positive bacteria (pneumococci, enterococci, β-haemolytic streptococci and S. aureus) found in blood cultures within 6 hours after signalling growth.

Methods: The tube coagulase test was optimized and several latex agglutination tests were compared and evaluated before a validation period of 11 months was performed on consecutive positive blood culture patient samples from Kalmar County Hospital, Sweden.