Thermo Scientific™ Bacitracin Discs

Description

Differentiate Lancefield Group A streptococci from other beta-haemolytic streptococci using Thermo Scientific™ Oxoid™ Bacitracin Discs. Bacitracin Discs help to save considerable time, labour and materials when used as a screening test prior to serological grouping.. Group A streptococci have been shown to be more sensitive to bacitracin than beta-haemolytic stains of other groups¹ allowing bacitracin to be used as a rapid diagnostic agent for presumptive identification of Group A streptococci.

Lancefield Group A streptococci (GAS) are mainly comprised of Streptococcus pyogenes, however S. dysgalactiae can also be Group A streptococci. S. pyogenes is a beta-haemolytic species of Gram positive bacteria that is responsible for a wide range of both invasive and non-invasive infections.  S. pyogenes is the most common bacterial cause of acute pharyngitis, accounting for 15-30% of cases in children and 5-10% of cases in adults.² 

Use Bacitracin Discs as a simple and practical screening technique for the routine clinical microbiology.

• Rapid differentiation of Lancefield Group A streptococci from other beta-haemolytic streptococci.
• Saves time, labour and materials when used as a screening test prior to serological grouping.
• Simple and ready-to-use.

Maxted¹ showed that Group A streptococci were more sensitive to bacitracin than beta-haemolytic strains of other groups, and that bacitracin might therefore be used as a rapid diagnostic agent for Group A streptoccoci. He found that only 1.7% of 2,386 bacitracin sensitive strains proved not to be Group A, and only 2.5% of 851 resistant strains were Group A. Levinson and Frank³ who employed impregnated paper discs for the same purpose, observed that 93.2% of 866 sensitive beta-haemolytic streptoccoci belonged to Group A. Streamer et al.⁴ compared bacitracin disc, fluorescent antibody and Lancefield precipitin techniques for the identification of Group A streptococci. The bacitracin disc technique was considered to be the simplest and most practical for the routine clinical laboratory.
The use of bacitracin sensitivity testing is not restricted to the differentiation of beta-haemolytic streptococci. Guthof⁵ found sensitivity to optochin, bacitracin, and furacin to be a useful test for distinguishing Aerococcus viridans and Streptococcus milleri from enterococci and mitis streptococci.

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Remel™ and Oxoid™ products are now part of the Thermo Scientific brand.