Streptococcus pyogenes (Group A streptococcus according to Lancefield grouping, GAS) is one of the most frequent infecting pathogen in children, occurring in the form of asymptomatic carriage, localised disease, organ disease and sepsis (1, 2). It may be the cause of different infections, such as pharyngitis and tonsillitis, lymphadenitis, scarlet fever, localized abscess (middle ear, sinuses, lungs, pleura, the meninges, appendages, joints and bones) as well as necrotising fasciitis, sepsis and toxic shock syndrome (1, 3). A group A streptococcal infection may result in complications, such as rheumatic fever with heart involvement and glomerulonephritis (1, 3). The incidence of invasive disease caused by Streptococcus pyogenes (S. pyogenes) in the world is estimated to be equal to 663 thousands cases a year (including 163 thousands deaths) (2). Polish National Institute of Public Health epidemiological reports from the last 3 years indicate constant increase in group A streptococcal invasive infections. In the year 2011 there was 3455 infections per year at incidence rate of 9.0/100 thousands; in the year 2012 there was 4286 infections per year at incidence rate of 11.1/100 thousands; in the year 2013 there was 5294 infections per year at incidence rate of 13.7/100 thousands; in the year 2014 there was 5597 infections per year at incidence rate of 14.54/100 thousands (4). This is probably associated with increasing virulence of the streptococcus and the presence of the M protein which blocks the complement system and inhibits phagocytosis (1, 3). Invasive infections are most prevalent in immunodeficient patients and patients with chronic diseases, although they occur also in immunocompetent patients (3).

Between 2010 and 2014, five paediatric patients (three females and two males) were hospitalised at the Clinical Paediatrics Department of Bielański Hospital in Warsaw with an invasive disease caused by group A streptococcus. The youngest patient was 3 years and 3 months old, and the oldest patient was 10 years old. Four patients were hospitalized from January to March, and one female patient with the diagnosis of soft tissue inflammation of the shin was hospitalized in July. All the paediatric patients were in a good condition, without immune disorder history (tab. 1).

Female patient (JK) aged 3 years and 3 months was admitted to the paediatric department with dyspnoea (SpO₂ 86%), dry cough and fever lasting for 3 days, with the temperature up to 39°C. Pneumonia was diagnosed with pleural reaction. Blood culture test result was proper. There was a need for pleural cavity drainage and 750 mL of fluid was extracted. The fluid culture showed an increase in S. pyogenes number. During hospitalization general condition improved (fig. 1 and 2).

Female patient (ZW) aged 3 years and 3 months was admitted to the paediatric department with the right shin swelling, fever up to 40°C and diarrhoea, which occurred twenty four hours before admission. Soft tissue inflammation of the shin and prerenal azotemia was diagnosed. The starting point of the infection was the wound caused by a mosquito bite. Although third generation cephalosporin was included in the treatment, the general condition of the girl deteriorated. Acute phase proteins concentration increased (CRP from 136.7 mg/l to 426 mg/l), as well as white blood cells (WBC from 17.1 thous./μl to 22.9 thous./μl), with insignificant decrease of procalcitonin concentration (PCT from 76.5 ng/ml to 58.6 ng/ml). During the first three days of the treatment the female patient still had a fever and her urea level was raised (72.4 ng/ml). Physical examination revealed meningism symptoms (neck stiffness, Brudzinski’s symptom). To rule out meningitis a lumbar puncture procedure was performed with the correct result. Several ultrasound examinations of the shin and surgical consultation was performed to rule out necrotising fasciitis. There were no indications for surgical intervention. After receiving the wound culture (S. pyogenes) result, the treatment was switched to crystalline penicillin with clindamycin. The general condition of the girl started to improve as fever as well as oedema and infiltration of the right shin subsided. After 4 days of antibiogram compliant treatment (penicilin, clindamycin susceptibility), the CRP and PCT values decreased considerably (51.6 mg/l and 1.2 ng/ml) accordingly).