To the Editors: Streptococcus pyogenes is currently an uncommon cause of early onset neonatal sepsis; however, it can be associated with mortality rates of up to 61% in low- and middle-income countries.1 We present the case of a term newborn who was admitted at 2 hours of life to the neonatal intensive care unit of a secondary-level hospital due to respiratory distress, after an uncomplicated vaginal delivery. Upon admission, a chest radiograph was performed, revealing a diffuse increase in density in both lung fields. Blood cultures were obtained, and laboratory tests were conducted. The laboratory tests revealed a markedly elevated interleukin-6 (19,265 pg/mL), and empirical antibiotic therapy with ampicillin and gentamicin was initiated. At approximately 18 hours of life, a positive blood polymerase chain reaction result for S. pyogenes was received, and antibiotic therapy was adjusted to ampicillin and clindamycin. On the third day of admission, the gynecology department contacted us to inquire about the microbiological results of our patient, as the mother had developed fever and general malaise. The positive result for S. pyogenes was reported and, given the suspicion of vertical transmission, it was suggested to perform a rapid antigen test for this organism at the vaginal level in the mother, although it is usually only validated for pharyngeal exudate. The result of this test was positive, and targeted antibiotic therapy was initiated, with good clinical evolution. Our patient showed a favorable evolution after the initiation of antibiotic therapy and, after hospital discharge, has no sequelae. The importance of recognizing this organism as a cause of invasive neonatal infection lies in its high mortality. Early onset sepsis (onset <72 hours of life) caused by this organism most commonly presents initially as respiratory distress,2,3 which may be followed by rapid deterioration. According to Sokou et al,2 vertical transmission of the organism may explain 94% of cases, with vaginal delivery being the most frequent. Despite this, the prevalence of vaginal carriers of S. pyogenes varies across studies. In Europe, according to Donders et al,4 there is a prevalence of 0.03%,4 and vaginal screening for this organism is not currently recommended. Nevertheless, given the severity that this condition may entail for both the neonate and the mother, the availability of rapid diagnostic tools for suspected cases would be beneficial, such as validation of pharyngeal antigen tests for vaginal use in detecting S. pyogenes. However, definitive diagnosis must be established by blood culture.
Iglesias et al. (Thu,) studied this question.