P3.S372: Fever, Otorrhea and Discomfort with Valsalva: An Unusual Presentation of Neonatal E. coli Infection

Introduction: Mastoiditis is a serious, uncommon complication of acute otitis media (1). It is commonly caused by S. pneumoniae, S. pyogenes, P. aeruginosa, H. influenzae, and anaerobes, with other gram-negative bacilli recovered infrequently (2, 10). It is uncommon in infants younger than six months with few case reports in children less than two months of age (3). Here, we report a case of a nine-day-old newborn with bilateral E. coli mastoiditis.

Case Description: A nine-day-old, full-term, otherwise healthy female was brought to the emergency department (ED) with increased fussiness and inconsolability with stooling. Parents also noted yellow-green drainage from the patient’s right ear. She was febrile in the ED to 38.1⁰C. Initial labs revealed profound neutropenia and elevated inflammatory markers. She was started empirically on ampicillin and cefepime in the setting of profound neutropenia. Culture of the ear drainage grew E. coli. Pediatric Otolaryngology was consulted and advanced imaging was obtained which revealed bilateral mastoid opacification with bony erosion and subperiosteal abscess formation (images 1 and 2). A small parapharyngeal abscess was also identified. The patient underwent an uncomplicated bilateral mastoidectomy. Intraoperative tissue cultures grew E. coli, which was also demonstrated on mastoid bone biopsy via 16s rRNA sequencing. She completed a 4-week parenteral antibiotic course with improvement in inflammatory markers and normalization of neutrophil counts. Follow-up imaging demonstrated resolution of the parapharyngeal abscess without signs of ongoing infection. Immunological work-up, including neutrophil oxidative burst function, was normal. Genetic testing for inborn errors of immunity was unrevealing.

Discussion: To our knowledge, there is only one other documented case of bilateral mastoiditis prior to one month of life (4, 5), which was due to S. pneumoniae and occurred in an infant with transient hypogammaglobulinemia (6). Unlike that case, our patient was ultimately found to be immunocompetent, despite her initial profound neutropenia, and presented with an unusual pathogen, potentially acquired perinatally. This case highlights the difficulty of diagnosing mastoiditis in neonates. Although limited reports of mastoiditis in children less than 6 months of age suggest that young patients present with obvious signs such as auricular displacement or posterior auricular edema similar to older toddlers (3, 11), our patient did not. Our patient presented with otorrhea and discomfort with stooling (i.e. Valsalva), which should prompt a more thorough otoscopic exam and early consideration for neuroimaging. A high index of suspicion combined with early recognition of nonspecific signs allowed for a timely diagnosis of neonatal mastoiditis, appropriate surgical intervention, and avoidance of a more fulminant course of disease.

Conclusion: Acute mastoiditis in the neonatal period is rare and should raise concern for an immunodeficiency (8, 9). Early symptoms may be subtle and neonatal pathogens along with typical pathogens of mastoiditis should be considered in empiric antibiotic decision-making.