A case of acute rheumatic fever in Italy: clinical and microbiological findings

Objectives. Acute rheumatic fever (ARF) is a post-infectious non-suppurative condition resulting from an autoimmune response to a Group A streptococcus (GAS) pharyngeal infection. In the last decades, the incidence of ARF showed a significant decrease in industrialized Countries. However, sporadic outbreaks have been reported in combination with the reappearance of certains emm-types of GAS. Here, we report a case of ARF occurred in a child from a primary school in Bologna, North of Italy. In addition, we describe the epidemiological investigation of GAS strains isolated from pharyngeal swabs collected during a surveillance program conducted in his classroom. Methods. In November 2012, a 11-year-old previously healthy white boy suffered for a GAS pharyngitis and was treated with clarithromycin for 10-days. In February 2013, he complained about left knee joint pain and retrosternal pain and was admitted to the hospital since a diagnosis of ARF was suspected. The patient underwent a complete clinical examination, an echocardiography and an electrocardiography (ECG). Several blood samples were taken to perform white blood cell count (WBC), antistreptolysine O titer (ASO) and inflammation markers. A pharyngeal swab was collected for GAS investigation. A surveillance program, based on pharyngeal swabs screening, was started in the classroom since case definition of ARF. Pharyngeal swabs were seeded on blood agar plates and β-haemolytic colonies were identified with mass-spectrometry (MALDI-TOF). In case of GAS isolation, antibiogram was performed using MICroSTREP plus1 panel (Microscan). Susceptibility was determined according to EUCAST criteria. Emm-type of each GAS isolates was determined by PCR and sequencing. Streptococcal pyrogenic exotoxin (spe) profile of each isolate, were performed by multiplex PCR Results. During hospitalization, echocardiography showed a mild mitral regurgitation. ECG revealed a first-degree atrioventricular block (PR=200-440 ms). The cardiac auscultation highlighted a faint systolic murmur. Blood tests showed an elevated ASO (2264 U/L) and inflammation markers and a mild leucocytosis (18.070/mmc). According to Jones criteria a diagnosis of ARF was established. A GAS strain showing a mucoid phenotype was isolated from pharyngeal swab of ARF case and the typing analysis conducted on it identified the presence of emm18 gene. Superantigen profile showed the presence of speA, speC, speG, speL, speM genes. Seven out of 24 pharyngeal swabs collected for surveillance resulted positive for GAS. Detailed microbiological characteristics are shown in table 1. Patient was given a therapy with corticosteroids for 21 days and benzilpenicillin (1.200.000 U im), with a gradual resolution of symptoms. Pharyngeal swab culture were negative after 2 weeks of hospitalization. Conclusion. Our case highlights that ARF has not disappeared in developed Countries. Moreover, as observed in our experience, a high circulation of certain mucoid GAS strains, like emm-type 18, could be a risk factor for ARF development.