Urinary tract infection must be excluded in febrile infants less than 3 months of age with positive respiratory syncytial virus antigen test

Abstract

Study objectives: The prevalence of significant bacterial infections in young infants who have respiratory syncytial virus (RSV) is unknown in the era after the introduction of <i>Haemophilus influenzae</i> and <i>Streptococcus pneumoniae</i> vaccinations. The evaluation of these infants remains controversial. We hypothesize that infants with fever and RSV are at low risk for secondary bacterial infection and may not require extensive and invasive laboratory evaluations. Methods: This was a prospective evaluation; all infants younger than 3 months from October 1998 to December 2003 who had a sepsis evaluation for fever and an RSV antigen test performed were eligible. Infants excluded were those with previous antibiotic use and immunosuppression. Results: There were 128 infants in the study; 50 (39%) were RSV positive, and 78 (61%) infants were RSV negative. Median age in the RSV-positive group was 44.3±19.4 days and in the RSV-negative group, 43.6±19.2 days. In the RSV-positive group, there were 30 (60%) boys, 11 (22%) whites, 29 (58%) blacks, and 10 (20%) Hispanics. In the RSV-negative group, there were 42 (53.8%) boys, 12 (15.3%) whites, 54 (69.2%) blacks, and 10 (12.8%) Hispanics. In the RSV-positive group, median temperature was 38.6±0.6°C, whereas in the RSV-negative group it was 38.5±0.5°C. In the RSV-positive group, mean pulse rate was 170.7±18.5 beats/min, with a pulse rate greater than 160 beats/min in 27 (54%) patients. In the RSV-negative group, mean pulse rate was 165.9±21.1 beats/min, with a pulse rate greater than 160 beats/min in 37 (47.4%) patients. In the RSV-positive group, mean respiratory rate was 48.2±18 breaths/min, with a respiratory rate greater than 60 breaths/min in 10 (20%) patients. In the RSV-negative group, mean respiratory rate was 44.2±15.9 breaths/min, with a respiratory rate greater than 60 breaths/min in 8 (10.2%) infants. There was no significant difference in vital signs between groups. There were more upper respiratory infection symptoms and coughing in the RSV-positive group (<i>P</i><.05). The number of patients admitted in the RSV-positive group was 38 (76%) versus 62 (79.4%) in the RSV-negative group. There were 6 (12%) infants admitted to the pediatric ICU in the RSV-positive group versus 1 (1.2%) in the RSV-negative group. The laboratory evaluation in the RSV-positive group included a CBC count of 46 (92%), urinalysis and culture 44 (88%), blood culture 45 (90%), chest radiograph 21 (62%), and CSF fluid analysis 22 (44%). In the RSV-negative group, the laboratory evaluation included a CBC count of 71 (91%), urinalysis and urine culture 71 (91%), blood culture 73 (93.5%), chest radiograph 36 (46.1%), and CSF fluid analysis 53 (67.9%). There were more chest radiographs performed in the RSV-positive group (<i>P</i><.05). There were 7 (14%) significant infections in the RSV-positive group versus 8 (10.2%) in the RSV-negative group. In the RSV-positive group, there were 5 (10%) instances of pneumonia and 1 (2%) instance of urinary tract infection (UTI). There were no significant positive blood culture results in the RSV-positive group, but there were 4 (8%) contaminant results. In the RSV-negative group, there were 4 (5.1%) instances of pneumonia, 3 (2.5%) of UTI, 1 (1.2%) of bacteremia with group B streptococcus, and 1 (1.2%) of meningitis with enterococcus. Conclusion: The risk of serious bacterial infection is low in the RSV-positive group, especially if one excludes pneumonias. There were no cases of bacteremia or meningitis; however, UTIs still are significant. Therefore, it may be prudent to exclude a UTI in febrile infants with a positive RSV antigen test. Further studies with greater numbers are needed to validate these results.