The Mycobacterial Growth Indicator Tube (MGIT; Becton Dickinson) system is a completely automated, nonradiometric, continuously monitoring, noninvasive instrument that requires neither needles nor other sharp instrument culture system (Hanna et al., 1999). Similar to Bactec 9000 MB, it uses the same oxygen-quenching fluorescence technology (Flanagan et al., 1999). It has greater capacity (960 bottles vs. 240 bottles) than other automated culture systems such as Bactec 460TB. This method detects MTB in 2 days (Epstein et al., 1998). Every 60 min, culture vials are monitored by instrument and based on specific growth algorithms are tagged as positive (Scarparo et al., 2002). This system is accepted as an alternative to radiometric culture system (Pfyffer et al., 1997b). Also, it is preferred by laboratory personnel as it is a safe and easy method (Cornfield et al., 1997). However, although it has significant safety advantages and is less labor intensive, the detection time for MTB, especially in smear-negative specimens, is longer than Bactec 460 TB (Chew et al., 1998). Morever, some studies have shown that this system has a higher contamination rate than radiometric Bactec 460 TB system (Hanna et al., 1999; Tortoli et al., 1999).
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