Evaluation of BACTEC MGIT 960 system for recovery of Nocardia from clinical specimens

Nocardia spp. is an aerobic Gram-positive bacillus responsible for nocardiosis. Herein, we performed a retro-spective study to evaluate the performance of BACTEC MGIT 960 system, in comparison with smear microscopy and blood agar plate (BAP) culture, to recover Nocardia from different clinical specimens. Furthermore, the inhibitory effect of antibiotics contained in MGIT 960 tube on Nocardia was also evaluated. The sensitivities for Nocardia recovery using smear microscopy, BAP culture, and MGIT 960 were 39.4% (54/137), 46.1% (99/215), and 81.3% (156/192), respectively. N. farcinica was the most detected species (60.4%, 136/225). In MGIT 960-recovered Nocardia strains, N. farcinica accounted for 76.9%. Furthermore, trimethoprim in MGIT 960 tube inhib-ited less N. farcinica growth than that of other Nocardia species, partially explaining why MGIT 960 recovered more N. farcinica from sputa. The current study demonstrated that MGIT 960 could recover Nocardia strains from heavily-contaminated samples if its components and antibiotics are redesigned.(c) 2023 Elsevier Inc. All rights reserved.

Automated summary

A retrospective study was conducted to evaluate the performance of the BACTEC MGIT 960 system in recovering Nocardia from different clinical specimens, compared to smear microscopy and blood agar plate culture. The study also assessed the inhibitory effect of antibiotics in the MGIT 960 tube on Nocardia. The results showed that MGIT 960 had the highest sensitivity for Nocardia recovery (81.3%), and N. farcinica was the most detected species (60.4%, 136/225). The study concluded that the components and antibiotics of the MGIT 960 system need to be redesigned for better recovery of Nocardia strains.