![]() ![]() However, these studies were limited to liquid medium, less used in resources limited sitting because of the high costs associated with them. Limited data have indicated that culture with mycobacterial Growth Indicator Tube (MGIT) supplemented with the Vancomycin, Amphotericin B and Nalidixic acid (VAN) combination and culture with Selective Kirchner medium supplemented with Vancomycin 10 mg/l (SKV) showed important reduction of culture contamination 18, 19. Fortunately, vancomycin, generally inactive on mycobacteria is active against SFB 16, 17, therefore, it was a potential candidate to include in the antibiotic combination used as a selective supplement for culture media. These contaminants, particularly resistant to biocides due to their ability to sporulate give for the first time, a stronger justification for high contamination rate of mycobacterial culture in Burkina Faso and also maybe in most resource limited sittings. However, knowing the species to which these contaminants belong would provide information on their likely origin (maybe for prevention), and would help to understand and to resolve the contamination issue. But no specific identification of SFB species has been carried out on these studies, excepted that of McClean et al. Recently in 2017, a basic characterization of sputum culture contaminants in Burkina-Faso, showed for the first time that SFB from the genus of Bacillus and related were the major residual contaminants 15. But possibly due to the difference in the context, none of them mentioned SFB as major contaminants. A few studies involved mycobacterial culture from different specimen (sputum, liquid gastric) on different media (liquid and solid) reported the presence of SFB among contaminants in mycobacterial cultures 9, 11, 12, 13, 14. Studies carried out in Ireland, in 2011, and in Uganda in 2014, showed that a Gram negative bacteria (Pseudomonas aeruginosa (47.2%), Serratia marcescens (13%)), and Gram positive bacteria excluding SFB ( Staphylococcus spp (50%) and Streptococcus spp (16%)), were respectively the main contaminant species isolated 9, 10. The literature reports little and different data about contaminants from LJ media. Indeed, the presence of an external envelope for Gram negative bacteria, of a wax coat for mycobacteria or a sporale coat for spore forming bacteria (SFB) lead to a variability of sensibility to biocides within the microorganisms 8. But the type of the contaminant microorganisms can influence the efficiency of the decontamination 7. The sputum culture process on LJ media, include a step of decontamination in order to eliminate contaminating microorganisms while protecting mycobacteria 6. However, the effectiveness of culture systems is greatly undermined by contamination with other bacteria and fungi 3, 4, 5. ![]() VCNT containing 10 µg of vancomycin is a good alternative method to reduce mycobacterial culture contamination.Ĭulture on solid media remains the gold standard for detecting TB and drug sensitivity testing 1, 2. Almost all identified strains were similar to those currently isolated in fermented traditional food suggesting in part food related contaminants. The most important SFB identified were B. The overall contamination rate on LJ with VCNT at 10 µg of vancomycin was statistically lower than which without VCNT (18.7% versus 43.8%) (p = 0.01). Eighteen (34%) isolates were non-reactive Bacillus. The most important species were Bacillus cereus (30%) and Bacillus licheniformis (21%). Thirty- five (66%) isolates representing 4 genera ( Bacillus, Paenibacillus, Brevisbacillus and Lysinibacillus) including 10 species were identified. ![]() API 50CH/B was performed and MALDI-TOF MS was used for external quality control. Bacteria cells and isolated colonies were described. SFB had been stored at −20 ☌ and identified after subculture onto 5% sheep blood Columbia agar and incubated at 37 ☌ during 24 h. The effectiveness of LJ with VCNT at 10 µg of Vancomycin were evaluated with sputum collected in the same period. Fifty-three SFB isolated between February 2016 and May 2017 were used. This study aims to identify the species of this contaminants and to evaluate the effectiveness of VCNT at 10 µg of vancomycin to reduce mycobacterial culture contamination mainly linked to SFB. A basic characterization of contaminants from LJ contaminated media showed that Gram positive Spore Forming Bacteria (SFB) were the major contaminants. The type of commensal microorganisms can influence the efficiency of sputum decontamination for TB diagnosis. ![]()
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