Streptococcus, instructions for use. How dangerous is the infection which last year, after the Covid pandemic, returned to record levels especially in younger children? And how to diagnose it correctly in order to start the right treatment quickly? This is explained in a study published in ‘Lancet Microbe’ by researchers from Paediatrics and Microbiology at the Fondazione Policlinico Gemelli Irccs and the Catholic University of Rome. “Yes to rapid tests in pharmacies, but only as screening. For a certain diagnosis – the experts recommend – it is best to use a throat-tonsillar swab, carried out in a microbiology laboratory. The typing of the most virulent strains, such as M1, it is also important” to follow the epidemiological trajectory”.
“Streptococcal infections were the nightmare of last year”, which recorded “a significant resurgence especially among pre-school children. In 2023, many children in bed with high fever and swollen tonsils, with pharmacies rushed for diagnostic tests.” This is the framework from which the analysis of the authors of the research began. Considering the 6 years from 2018 to 2023, the work investigated the incidence of Streptococcus pyogenes (Gas) infection, analyzed by the privileged observatory of the Gemelli pediatric emergency room directed by Antonio Chiaretti, associate of general and specialist pediatrics at the Cattolica , which collected over 1,800 samples over the period examined.
What happened after the pandemic
“In the years of the Covid pandemic, that is, from 2020 to 2022 – describes Maurizio Sanguinetti, professor of Microbiology at the Cattolica, director of the Department of Laboratory and Infectious Sciences and of the Microbiology Unit of the Gemelli Polyclinic – we observed a significant reduction in streptococcal infections, both in terms of quantity of samples received (due to reduced access to our hospital clinic), but also a significant reduction in the percentage of positive samples. Non-pharmacological protection measures, such as masks, have reduced contact with the microorganism in recent years and the infection. However, when these protections were removed in 2023, we observed a restart of the infection, with an incidence quickly returning to the levels of the pre-pandemic period, when positive samples were 13-16% of all those examined”. But the real difference recorded in 2023, compared to the previous one – the specialists underline – was that the age group affected was not the usual one, i.e. children of school age and pre-adolescence, but a much lower one, from 3 to 6 years.
“The suspicion – reasons Sanguinetti – is that the children, having been significantly protected by staying at home and wearing masks, have not developed normal, partially protective immunity against the infection”.
“This is a very important concept – explains the expert – which concerns the benefits of coming into contact with microorganisms. During the pandemic, due to causes of force majeure, there has been a massive use of protection tools which have generally reduced contact with all microorganisms is essential for ‘training’ our immune system to respond to infections a so-called ‘immunological debt’ which prevented them from developing protection, even partial, against the microorganism and this led to a greater incidence of infections. Therefore, while on the one hand protection from infections is fundamental, especially in a time of emergency as was the case with the Covid-19 pandemic, it is equally clear that contact with microorganisms also acts as ‘prevention’, because low-level contact determines the development of a certain protection, the establishment of a certain immunity which is then reactivated more effectively when it comes into contact with the microorganism”.
“With respect to the epidemiological evolution – notes Sanguinetti – our research and various other evidence published in the literature point to many small outbreaks of Streptococcus pyogenes almost everywhere, with an increase in invasive pathologies linked in particular to the M1 immunotype, which is the most serious and virulent. This brings us to another important reflection, namely that the diagnosis of these infections must be carried out appropriately”.
The tests
“Rapid antigen tests carried out in pharmacies – Sanguinetti remarks – they can be a valid screening tool, even if they are burdened by many false positive and false negative results. But if a child is highly symptomatic (high fever, enlarged and inflamed tonsils) and tests negative on the rapid test, it would be appropriate to repeat the test in a laboratory to confirm this diagnosis. The same reasoning also applies in the case of a positive rapid test: only a throat-tonsillar swab carried out in the laboratory, followed by a culture test (and a possible in vitro drug sensitivity test, i.e. an antibiogram), allows the microorganism to be characterized , with both diagnostic and epidemiological implications to evaluate the possible circulation of hyper-virulent strains. So yes to the test in the pharmacy, but in some cases it must be supplemented by a confirmation/in-depth analysis in the laboratory“.
“No alarmism – concludes the specialist – because this is a disease that we know well, but at the same time we must avoid being superficial, because in 2023 there was a significant resurgence and because this microorganism can cause invasive infections, even in healthy individuals, and important sequelae years later, at the level of the kidneys (post-streptococcal glomerulonephritis), heart valves and joints, in particular in the case of the M1 strain”.
