ST20 Staphylococcus aureus causing suppurative cervical lymphadenitis in an extremely low-birth-weight infant.

Neonatal suppurative cervical lymphadenitis is uncommon, particularly in extremely low-birth-weight infants. We report a 772 g infant born at 28 weeks of gestation who developed rapidly progressive unilateral cervical lymphadenitis caused by methicillin-susceptible Staphylococcus aureus (MSSA) on postnatal day 31. The infant remained afebrile and blood cultures were negative despite progression requiring repeated drainage. The cervical isolate was genotyped as ST20/spa-t3929 and shared an identical genetic profile with an earlier pharyngeal isolate, suggesting that the infection arose from pre-existing S. aureus colonization. This case highlights the potential for ST20 MSSA to cause localized invasive infection in preterm infants.