A case of group B streptococcal bacteremia presenting with lumbar cellulitis in a 52-day-old infant

Group B Streptococcus (GBS) is a leading cause of invasive infections in infants under 3 months of age. While late-onset GBS disease (LOD) typically presents as bacteremia or meningitis, focal skin infections such as cellulitis are less common.

A 52-day-old full-term female infant presented with fever and localized erythema in the lumbar region on the day of symptom onset. Her mother had tested positive for GBS during pregnancy and received intrapartum antibiotic prophylaxis. On admission, her vital signs were as follows: temperature, 37.8 °C; heart rate, 124 bpm; respiratory rate, 28 breaths/min; and blood pressure, 100/62 mmHg. Physical examination revealed no other signs of skin infection. Blood and throat cultures were positive for GBS (serotype Ib), and magnetic resonance imaging ruled out osteomyelitis or abscess. Lumbar puncture was deferred because of the location of the inflammation. The patient received intravenous ampicillin for 21 days. The fever and erythema alleviated rapidly by day 2 of hospitalization.

Lumbar cellulitis is an unusual manifestation of LOD. Although breast milk has been implicated in recurrent GBS infections, current evidence does not support the routine cessation of breastfeeding after a single episode. The findings from this case highlight the importance of recognizing the atypical presentations of GBS. Individualized decisions regarding breastfeeding, supported by close follow-up, may be appropriate after LOD without recurrence.