[Aetiology and outcomes of potentially serious infections in febrile infants less than 3 months old]

Background: Recent studies have shown changes in the aetiology of serious bacterial infections in febrile infants ≤ 90 days of age. The aim of this study was to describe the current microbiology and outcomes of these infections in Spain.

Material and methods: Sub-analysis of a prospective multicentre study focusing on febrile infants of less than 91 days of life, admitted between October 2011 and September 2013 to Emergency Departments of 19 Spanish hospitals, members of the Spanish Paediatric Emergency Research Group of the Spanish Society of Paediatric Emergencies (RISeuP/SPERG).

Results: The analysis included 3,401 febrile infants ≤90 days of age with fever without source. There were 896 positive cultures: 766 urine (85.5%), 100 blood (11.2%), 18 cerebrospinal fluid (2%), 10 stool, and 2 umbilical cultures. Among the 3,401 infants included, 784 (23%) were diagnosed with a serious bacterial infection, and 107 of them (3.1%) with an invasive infection. E. coli was the most common pathogen isolated from urine (628; 82%), blood (46; 46%), and cerebrospinal fluid cultures (7; 38.9%), followed by S. agalactiae that was isolated from 24 (24%) blood cultures and 3 (16.7%) cerebrospinal fluid cultures. There were only 2 L. monocytogenes infections. Four children died, and seven had severe complications.

Conclusions: Among infants ≤ 90 days of age with fever without source, E. coli was the most common pathogen isolated from urine, blood, and cerebrospinal fluid cultures.