Abstract: Objective  In the course of culture, adopting a way of using magnetic nanoparticle to concentrate mycobacteria, and evaluated its feasibility. Methods  Ninety-four clinical specimens from outpatients and inpatients with pulmonary tuberculosis were collected during December 2012 to March 2013 in Nanjing Chest Hospital and were concentrated by PEG600 magnetic nanoparticle self-made or centrifugation (3000×g, 20 min), and inoculated. After incubating, we compared their results of positive rate, contamination rate and average culture time with the way of direct inoculation. For count data, the chi-square test was used for statistical analysis. Kolmogorov-Smirnov normality test was performed, and data non-normally distributed was analyzed by using the Wilcoxon rank sum test, P<0.05 was considered statistically significant. Results  The positive rates of direct, centrifugal, bead enrichment method were 29.79%(28/94), 43.62%(41/94) and 41.49%(39/94) respectively; Contamination rates were 2.91%(3/103), 4.85%(5/103) and 3.88%(4/103) respectively; Average culture time(day)［Median(upper and lower quartile)］ were 28(21，40), 21(21，35), 21(21，35), respectively. The positive rates of bead enrichment and centrifugal method were statistically higher than simple method, their values ofχ² were 9.09, 11.08 respectively, both P<0.01. The average culture times of bead enrichment and centrifugal method were statistically shorten than simple method, their values of Z were －3.983 and －3.980 respectively, both P<0.01. There did not show significantly difference between centrifugal and bead enrichment method about their positive rates and average culture times(about positive rate：χ²＝0.25，P=0.62；about average culture times：Z=－0.557，P=0.577). Conclusion  The bead enrichment method had a higher positive rate and a shorten average culture time than simple method, and had the similar results gotten from the centrifugal method, little contamination to environment and easy batch processing; therefore had good prospects for clinical application.

Key words: Mycobacterium, Specimen handling, Iron compounds, Nanoparticles, Bacteriological techniques