ABSTRACT
OBJECTIVE@#To evaluate luciferase reporter phage (LRP) phAE85 in rapid detection of rifampicin resistance in a region where TB is endemic.@*METHODS@#One hundred and ninety primary isolates on Lowenstein-Jensen medium were tested. Middlebrook 7H9 complete medium with and without rifampicin at 2 μg/mL was inoculated with standard inoculum from suspensions of the clinical isolate. After incubation for 72 h, LRP was added. Following 4 h of further incubation, light output from both control and test was measured as relative light units. Strains exhibiting a reduction of less than 50% relative light units in the drug containing vial compared to control were classified as resistant. Results were compared with the conventional minimum inhibitory concentration method (MIC) of drug susceptibility testing.@*RESULTS@#The two methods showed high level of agreement of 97% (CI 0.94, 0.99) and P value was 0.000 1. The sensitivity and specificity of LRP assay for detection of rifampicin resistance were 91% (CI 0.75, 0.98) and 99% (CI 0.95, 1.00) respectively. Time to detection of resistance by LRP assay was 3 d in comparison with 28 d by the minimum inhibitory concentration method.@*CONCLUSIONS@#LRP assay with phAE85 is 99% specific, 91% sensitive and is highly reproducible. Thus the assay offers a simple procedure for drug sensitivity testing, within the scope of semi-automation.
Subject(s)
Humans , Antibiotics, Antitubercular , Pharmacology , Drug Resistance, Bacterial , Genes, Reporter , Luciferases , Genetics , Metabolism , Microbial Sensitivity Tests , Mycobacteriophages , Genetics , Physiology , Mycobacterium tuberculosis , Virology , Rifampin , Pharmacology , Sensitivity and Specificity , Tuberculosis, Multidrug-Resistant , MicrobiologyABSTRACT
<p><b>OBJECTIVE</b>To study the effect of phage lysin on the growth of lysogens.</p><p><b>METHODS</b>Sputum specimens processed by modified Petroff's method were respectively treated with phagebiotics in combination with lysin and lysin alone. The specimens were incubated at 37 °C for 4 days. At the end of day 1, 2, 3 and day 4, the specimens were streaked on blood agar plates and incubated at 37 °C for 18-24 hours. The growth of normal flora observed after day 1 was considered as lysogens.</p><p><b>RESULTS</b>Sputum specimens treated with phagebiotics-lysin showed the growth of lysogens. When specimens treated with lysin alone, lysogen formation was avoided and normal flora was controlled.</p><p><b>CONCLUSIONS</b>Lysin may have no effect on the growth of lysogens.</p>
Subject(s)
Bacteria , Bacteriophages , Lysogeny , Microbial Viability , Mucoproteins , Metabolism , Sputum , Microbiology , Temperature , Time FactorsABSTRACT
Objective: To study the effect of phage lysin on the growth of lysogens. Methods: Sputum specimens processed by modified Petroff's method were respectively treated with phagebiotics in combination with lysin and lysin alone. The specimens were incubated at 37℃ for 4 days. At the end of day 1, 2, 3 and day 4, the specimens were streaked on blood agar plates and incubated at 37℃ for 18-24 hours. The growth of normal flora observed after day 1 was considered as lysogens.Results:When specimens treated with lysin alone, lysogen formation was avoided and normal flora was controlled. Conclusions: Lysin may have no effect on the growth of lysogens. Sputum specimens treated with phagebiotics-lysin showed the growth of lysogens.