Non-beta-haemolytic variants of Streptococcus pyogenes: a challenge for the microbiology laboratory

摘要

Streptococcus pyogenes is one of the most important human pathogens isolated in the clinical diagnostic microbiology laboratory. It is carried asymptomatically, usually in the upper respiratory tract, in 5-30% of healthy individuals. It also causes a wide spectrum of disease, ranging from superficial skin infection and pharyngitis to more invasive disease such as bacteraemia, necrotising fasciitis and streptococcal toxic shock syndrome (streptococcal TSS). Death occurs in 10-15% of patients with invasive S. pyogenes infection/ with mortality from streptococcal TSS reported at up to 44% . S. pyogenes infection is also causally linked with delayed non-suppurative post-streptococcal sequelae such as acute rheumatic fever and glomerulonephritis. S. pyogenes is classified as group A Streptococcus (GAS) by Lancefield grouping.