RISK OF SERIOUS BACTERIAL INFECTION IN YOUNG FEBRILE INFANTS WITH RESPIRATORY SYNCYTIAL VIRUS INFECTIONS.

Levine DA, et al. Pediatrics. 2004 Jun;113(6):1728-34.

BACKGROUND: The evaluation of young febrile infants is controversial, in part because it is unclear whether clinical evidence of a viral infection significantly reduces the risk of serious bacterial infections (SBIs). Specifically, it remains unclear whether the risk of SBI is altered in a meaningful way in the presence of respiratory syncytial virus (RSV) infections.

OBJECTIVE: The objective of this study was to determine the risk of SBI in young febrile infants who are infected with RSV compared with those without RSV infections.

METHODS: We conducted a 3-year multicenter, prospective, cross-sectional study. All febrile (> or =38 degrees C) infants who were < or =60 days of age and presented to any of 8 pediatric emergency departments from October through March 1998-2001 were eligible. General clinical appearance was evaluated using the Yale Observational Scale. We determined RSV status by antigen testing of nasopharyngeal secretions. We defined bronchiolitis as either wheezing alone or chest retractions in association with an upper respiratory infection. We evaluated infants with blood, urine, cerebrospinal fluid, and stool cultures. Urinary tract infection (UTI) was defined by single pathogen growth of > or =5 x 10(4) cfu/mL, or > or =10(4) cfu/mL in association with a positive urinalysis in a catheterized specimen, or > or = 10(3) cfu/mL in a suprapubic aspirate. Bacteremia, bacterial meningitis, and bacterial enteritis were defined by growth of a known bacterial pathogen. SBI was defined as any of the above-mentioned 4 bacterial infections.

RESULTS: We enrolled 1248 patients, including 269 (22%) with RSV infections. The overall SBI status could be determined in 1169 (94%) of the 1248 patients, and the rate of SBIs was 11.4% (133 of 1169; 95% confidence interval [CI]: 9.6%-13.3%). The rate of SBIs in the RSV-positive infants was 7.0% (17 of 244; 95% CI: 4.1%-10.9%) compared with 12.5% (116 of 925; 95% CI: 10.5%-14.8%) in the RSV-negative infants (risk difference: 5.5%; 95% CI: 1.7%-9.4%). The rate of UTI in the RSV-positive infants was 5.4% (14 of 261; 95% CI: 3.0%-8.8%) compared with 10.1% (98 of 966; 95% CI: 8.3%-12.2%) in the RSV-negative infants (risk difference: 4.7%; 95% CI: 1.4%-8.1%). The RSV-positive infants had a lower rate of bacteremia than the RSV-negative infants (1.1% vs 2.3%; risk difference: 1.2%; 95% CI: -0.4% to 2.7%). No RSV-positive infant had bacterial meningitis (0 of 251; 95% CI: 0%-1.2%); however, the differences between the 2 groups with regard to bacteremia and bacterial meningitis did not achieve statistical significance.

CONCLUSIONS: Febrile infants who are < or =60 days of age and have RSV infections are at significantly lower risk of SBI than febrile infants without RSV infection. Nevertheless, the rate of SBIs, particularly as a result of UTI, remains appreciable in febrile RSV-positive infants.

PREVALENCE OF SERIOUS BACTERIAL INFECTIONS IN FEBRILE INFANTS WITH RESPIRATORY SYNCYTIAL VIRUS INFECTION.

Titus MO, Wright SW. Pediatrics. 2003 Aug;112(2):282-4.

OBJECTIVE: Neonates with fever generally undergo a full, invasive septic evaluation to exclude serious bacterial infection (SBI). The risk of SBI in febrile older infants and children with documented respiratory syncytial virus (RSV) infection has been found to be negligible. The purpose of this study was to investigate the prevalence of SBI in febrile infants who were younger than 8 weeks and had documented RSV infection and to compare the risk of SBI with control subjects who were febrile and RSV-negative.

METHODS: This was a retrospective cohort study of infants who were age 8 weeks or less and presented with documented fever to the emergency department at an urban children's hospital in October through April during a 4-year period. RSV-positive cases were gender- and age-matched to febrile RSV-negative control subjects. Clinical characteristics and the rate of SBI were compared between the 2 groups.

RESULTS: A total of 174 previously healthy infants with fever and a positive RSV antigen test were identified and matched with 174 previously healthy infants with fever and a negative RSV test. Infants with RSV infection were more likely to present with upper respiratory infection symptoms, increased work of breathing, and apnea. Overall, 2 patients in the RSV group had SBI (both with urinary tract infections), compared with 22 in the control group (relative risk: 0.009), 17 of which were urinary tract infections.

CONCLUSIONS: The risk of SBI in febrile infants with RSV infection seems to be very low, particularly in comparison with a control group of RSV-negative infants. These data suggest that full septic evaluations are not necessary in nontoxic-appearing infants with a positive RSV test. It seems to be prudent to examine the urine in these infants, as there is a clinically relevant rate of urinary tract infection.

COMMENT: This may spare a nontoxic, febrile child from getting a lumbar puncture. However, admission is still indicated for children less than 2 months as there is still a risk of apnea.