Neonatal varicella complicated by Staphylococcus aureus lung abscess in a preterm infant: a case report.

BACKGROUND: Neonatal varicella is a rare but potentially life-threatening condition, particularly in preterm infants. Although secondary bacterial infections are common complications, deep organ involvement such as lung abscess formation is exceedingly rare. Reports describing neonatal varicella complicated by Staphylococcus aureus lung abscess are scarce.

CASE PRESENTATION: We report a 26-day-old preterm infant (32 weeks' gestation, birth weight 1.94 kg) who developed a progressive vesiculopustular skin lesions and respiratory deterioration following exposure to maternal varicella. Despite initial topical treatment, the rash rapidly worsened and was accompanied by poor responsiveness, apnea, cyanosis, and hypothermia. On admission, the infant presented with extensive skin lesions, respiratory distress requiring non-invasive ventilation, coagulopathy, and thrombocytopenia. Intravenous acyclovir and immunoglobulin were initiated. Although the skin lesions gradually crusted and resolved, respiratory abnormalities persisted and oxygen supplementation remained necessary. Chest imaging subsequently revealed a right upper lobe abscess. Blood cultures remained negative; however, respiratory metagenomic next-generation sequencing (mNGS) identified Staphylococcus aureus, confirming secondary bacterial infection. Initial antibiotic therapy with vancomycin was selected because of severe pulmonary infection and the local prevalence of oxacillin-resistant Staphylococcus aureus. However, subtherapeutic trough concentrations and limited clinical response prompted a switch to linezolid. Following treatment adjustment, the infant showed gradual clinical and radiographic improvement and was discharged in stable condition. Follow-up imaging confirmed complete resolution of the lung abscess.

CONCLUSIONS: This case represents a rare presentation of neonatal varicella complicated by Staphylococcus aureus lung abscess in a preterm infant. It highlights that apparent resolution of cutaneous lesions does not exclude ongoing deep-seated bacterial infection and that persistent respiratory abnormalities should prompt early imaging evaluation, even in the absence of typical respiratory signs. In culture-negative cases, mNGS may facilitate pathogen identification and guide targeted antimicrobial therapy. Early recognition, individualized antimicrobial management, and therapeutic drug monitoring are important for optimizing outcomes in high-risk neonates. This case also underscores the importance of timely post-exposure prophylaxis and the limited availability of varicella-zoster immune globulin (VZIG) in some regions.