Invasive group A Streptococcus infection (Streptococcus pyogenes): Current situation in Spain

Abstract

Group A ß-hemolytic Streptococcus (S. pyogenes), also known as GAS, is a Gram-positive bacterium. It can be easily identified in the microbiology laboratory by its ability to hemolyse blood in culture media. This bacterium is highly virulent due to its production of enzymes and toxins, and its ability to cause immunologically mediated diseases such as rheumatic fever and post-streptococcal glomerulonephritis. GAS is the primary cause of bacterial pharyngotonsillitis, although it is typically a benign and non-invasive disease. However, it also has the potential to cause severe skin and soft tissue infections, necrotising fasciitis, bacteraemia and endocarditis, pneumonia and empyema, and streptococcal toxic shock syndrome, without any age or predisposition limits. The term invasive GAS disease (iGAS) is used to refer to this group of conditions. In more developed countries, iGAS disease has declined thanks to improved hygiene and the availability of antibiotics. For example, rheumatic fever has practically disappeared in countries such as Spain. However, recent data suggests a potential increase in some iGAS diseases, although the accuracy of this data is not consistent. Because of this, the COVID and Emerging Pathogens Committee of the Illustrious Official College of Physicians of Madrid (ICOMEM) has posed several questions about invasive GAS infection, especially its current situation in Spain. The committee has enlisted the help of several experts in the field to answer these questions. The following lines contain the answers that we have collaboratively produced, aiming to assist not only the members of ICOMEM but also anyone interested in this topic.

Keywords: Streptococcus pyogenes; bacteraemia; empyema; endocarditis; explosive pleuritis; glomerulonephritis; group A streptococcus; necrotising fasciitis; pharyngotonsillitis; pneumonia; rheumatic fever; skin and soft tissue infection; streptococcal toxic shock syndrome.

Figure 1

Complete haemolysis in a culture medium enriched with blood from S. pyogenes

Figure 2

Incidence of rheumatic fever in Denmark and mortality of rheumatic fever in the United States. Taken from Alm PA [24] CC-BY license, version 4.0

Figure 3

Evolution of bacteraemia episodes per 100,000 inhabitants of GAS in four large hospitals in Madrid

Figure 4

Evolution of episodes of GAS bacteraemia per 1000 hospital admissions in 4 large hospitals in Madrid

Figure 5

S. pyogenes necrotising fasciitis

Figure 6

Estimated number of cases and deaths due to invasive GAS disease in USA [117,118].