477. Risk Factors for Serious Bacterial Infections in Infants 1 Week to 3 Months
Session: Poster Abstract Session: Pediatric Infections: Bacterial and Parasite
Thursday, October 18, 2012
Room: SDCC Poster Hall F-H
Background: Serious bacterial infections (SBIs) in young infants have remained an important ongoing concern for decades. Despite decades of research, a comprehensive review of incidence rate and current risk factors has not been performed.

Methods: We conducted a retrospective analysis of all blood, urine, cerebral spinal fluid (CSF) and stool cultures collected at Kaiser Permanente Northern California (KPNC) on full term, previously healthy infants age presenting for care between 1 week to 3 months from January 01, 2005 through September 30, 2011.  Potential cases were defined as infants with positive cultures collected in the outpatient setting, emergency department or first 24 hours of hospitalization. Manual chart review was conducted on all possible pathogens.

Results:  A total of 216,005 full-term births occurred during the study period.  892 infants had 1030 SBIs: 125 bacteremia, 867 urinary tract infections (UTIs), 16 bacterial meningitis, and 22 bacterial gastroenteritis.  58% of infants were male with 4.7% circumcised.

The incidence rate of serious bacterial infection was 4.8/1000 full term births. Bacteremia, UTI, meningitis and bacterial gastroenteritis occurred in 0.58/1000, 4.01/1000, 0.08/1000, and 0.10 /1000 full term births, respectively. Gram negative pathogens accounted for 92% of pathogens. The most common pathogen was Escherichia coli (809/946, 86%) causing 52 cases of bacteremia, 750 of UTI and 7 of meningitis.  Eighty-four pathogens were gram positive, with 23 (27%) Group B Streptococcus (GBS) including 6 cases of meningitis. Salmonella sp. caused the majority of bacterial gastroenteritis.

White blood cell (WBC) count >15,000 occurred in 41% (350/841) of infants with a SBI.  Viral co-infections and abnormal chest radiograph occurred in 20/158 (13%) of infants and 58/456 (13%), respectively. The GBS status of infants’ mothers was 26% positive, 70% negative and 4% unknown. 

Conclusion: Our study indicates SBIs in young infants occurs in 4.8 / 1000 full term live births. E. coli remains the most common pathogen to cause UTI, bacteremia and meningitis. Based on the epidemiology of pathogens found in this large cohort, these data suggest that SBI is a rare occurrence and UTI is the most important predictor for bacteremia and meningitis.

Tara Greenhow, MD, Pediatric Infectious Diseases, Kaiser Permanente Northern California, San Francisco, CA; UCSF, San Francisco, CA, Yun-Yi Hung, PhD, Kaiser Permanente Northern California, Oakland, CA and Arnd Herz, MD, Kaiser Permanente Northern California, Hayward, CA


T. Greenhow, None

Y. Y. Hung, None

A. Herz, None

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