ABSTRACT
BACKGROUND: The combined use of liquid media and solid media is recommended for mycobacterial culture. We evaluated diagnostic performance of combination of BACTEC Mycobacteria Growth Indicator Tube (MGIT; Becton Dickinson, USA) and 2% Ogawa media (Korean Institute of Tuberculosis, Korea) for recovery of mycobacteria. METHODS: In September 2007, 1,764 specimens from 1,059 patients were cultured with MGIT and Ogawa. Acid fast bacilli (AFB) smear was fluorochrome-stained. The isolates were identified into Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM) with PCR using Seeplex TB Detection Kit (Seegene, Korea). Recovery rate, time to detection (TTD), contamination rate, mixed growth rate and species distribution were analyzed. RESULTS: Two hundred thirty-five specimens (13.3%) from 165 patients (15.6%) were positive for mycobacterial culture. Recovery rates of mycobacteria from the group using both media, MGIT only, and Ogawa only were 13.3%, 12.1%, and 7.8%, respectively. While MGIT recovered 98.9% of MTB and 79.7% of NTM, Ogawa recovered 65.9% of MTB and 54.1% of NTM. TTDs of total mycobacteria/MTB/NTM in MGIT and Ogawa were 10.6/11.4/9.7 days and 31/29/33 days, respectively. MGIT TTDs of total mycobacteria/MTB/NTM from AFB-positive specimens were significantly shorter than those of AFB-negative specimens; 8.2/9.5/4.4 days vs 11.6/12.7/10.7 days. Contamination and mixed growth rate of MGIT were 9.6% and 3.7%. Primary culture of Ogawa recovered 1 MTB and 1 NTM among the 170 MGIT-contaminated specimens and 38 mycobacteria among 66 specimens that showed mixed cultures of MGIT. CONCLUSIONS: MGIT warrants sensitive and rapid isolation of mycobacteria. However, the combination of MGIT and Ogawa is more desirable to recover mycobacteria in the case of contaminations or mixed cultures.
Subject(s)
Humans , Culture Media , False Positive Reactions , Mycobacterium/growth & development , Mycobacterium Infections/diagnosis , Mycobacterium tuberculosis/growth & development , Reagent Kits, Diagnostic , Sensitivity and Specificity , Sputum/microbiology , Time FactorsABSTRACT
BACKGROUND: As many as several weeks of incubation may be necessary for the recovery of mycobacteria when conventional culture media are used. Previous studies evaluating Mycobacteria Growth Indicator Tube (MGIT) as a rapid for the growth and detection of mycobacteria from clinical specimens have been reported. We compared MGIT with Ogawa media for the recovery of mycobacteria from clinical specimens. METHODS: Ninety nine clinical specimens received in the laboratory of Wonju Christian Hospital from June to September 199 were used for this study. The specimens from nonsterile body sites were digested, decontaminated, and concentrated, for culture and Ziehl-Neelsen stain, and specimen were inoculated onto MGIT tube and 3% Ogawa egg medium, and cultured for 8 weeks. RESULTS: Of the 38 specimens culture-positive for mycobacteria, 3 grew isolates in MGIT medium only, 8 grew isolates in Ogawa media only, and 27 grew isolates in both media. Mean (median, range) times to detection of mycobacteria were 13.7 (5.5, 2-48) days with MGIT and 19.6 (18, 13-37) days with Ogawa (P>0.05). The number recovered with MGIT plus Ogawa media was 24 (63.2%) within 14 days of receipt of specimen, and 31 (81.6%) within 21 days. The contamination rates were 31 % for MGIT and 1 % for Ogawa media. CONCLUSIONS: MGIT appears useful to quickly detect and identify mycobacteria from clinical specimens. However, because the number of culture-positive specimen in MGIT was not greater than those recovered with Ogawa media, MGIT should be used in combination with solid media to reduce turnaround times and increase the isolation rate.
Subject(s)
Culture Media , Mycobacterium , OvumABSTRACT
BACKGROUND: As many as several weeks of incubation may be necessary for the recovery of mycobacteria when conventional culture media are used. Previous studies evaluating Mycobacteria Growth Indicator Tube (MGIT) as a rapid for the growth and detection of mycobacteria from clinical specimens have been reported. We compared MGIT with Ogawa media for the recovery of mycobacteria from clinical specimens. METHODS: Ninety nine clinical specimens received in the laboratory of Wonju Christian Hospital from June to September 199 were used for this study. The specimens from nonsterile body sites were digested, decontaminated, and concentrated, for culture and Ziehl-Neelsen stain, and specimen were inoculated onto MGIT tube and 3% Ogawa egg medium, and cultured for 8 weeks. RESULTS: Of the 38 specimens culture-positive for mycobacteria, 3 grew isolates in MGIT medium only, 8 grew isolates in Ogawa media only, and 27 grew isolates in both media. Mean (median, range) times to detection of mycobacteria were 13.7 (5.5, 2-48) days with MGIT and 19.6 (18, 13-37) days with Ogawa (P>0.05). The number recovered with MGIT plus Ogawa media was 24 (63.2%) within 14 days of receipt of specimen, and 31 (81.6%) within 21 days. The contamination rates were 31 % for MGIT and 1 % for Ogawa media. CONCLUSIONS: MGIT appears useful to quickly detect and identify mycobacteria from clinical specimens. However, because the number of culture-positive specimen in MGIT was not greater than those recovered with Ogawa media, MGIT should be used in combination with solid media to reduce turnaround times and increase the isolation rate.
Subject(s)
Culture Media , Mycobacterium , OvumABSTRACT
BACKGROUND: BACTEC MGIT 960 system(Becton Dickinson, USA; MGIT 960) is a fully automated, noninvasive culture system for mycobacteria, which has been regarded as a sensitive and least labor-intensive method. This study was purposed to evaluate the performance of MGIT 960 compared to BACTEC 460 TB radiometric system(Becton Dickinson, USA; BACTEC 460) and Ogawa media. METHODS: A total of 1,067 clinical specimens submitted from April to June in 1999 was cultured for acid fast bacilli(AFB). All specimens were digested, decontaminated by the 6% sodium hydroxide(final concentration of 1.5%) and 0.5% N-acetyl-L-cysteine method. All specimens were inoculated into three kinds of media: a MGIT, a BACTEC 12B, and an Ogawa medium. The AFB recovered from cultures were identified to M. tuberculosis complex and MOTT by NAP test. RESULTS: Of 106 isolates of M. tuberculosis recovered from all culture systems, 101(95.3 %) were detected in the MGIT 960, 95(89.6%) in the BACTEC 460 and 76(71.7%) on Ogawa media. MGIT 960 plus Ogawa media detected 104(98.1%) isolates and BACTEC 460 plus Ogawa media recovered 96(90.6%) isolates. The mean time required for detection of M. tuberculosis was 12.7+/-5.8 days with MGIT 960, 16.2+/-7.7 days with BACTEC 460, and 22.8+/-9.5 days with Ogawa media. The contamination rate were 5.1% for MGIT 960, 2.7% for BACTEC 460, and 6.7% for Ogawa media. CONCLUSIONS: MGIT 960 is a sensitive and rapid method to isolate M. tuberculosis.