Utility of direct fluorescent antibody testing of nasopharyngeal washes in children with and without respiratory tract illness.
BACKGROUND
Direct fluorescent antibody (DFA) testing of nasopharyngeal wash specimens is a rapid and reliable means of diagnosing respiratory viral infection. The utility of DFA testing in the evaluation of febrile children without respiratory symptoms has not been critically evaluated. It is not known whether clinical or demographic factors apart from respiratory symptoms are associated with a positive DFA or whether a positive DFA is more likely to be associated with lower or upper respiratory tract symptoms (RTS).


METHODS
This is a retrospective case-series of 756 consecutive nasopharyngeal specimens with respiratory DFA testing performed at the University of California San Francisco from November 1, 2002 through October 31, 2003.


RESULTS
No RTS was a statistically significant predictor of negative DFA [odds ratio (OR), 0.03; 95% confidence interval (CI), 0.004-0.2; P = 0.001] compared with lower RTS. Male subjects were more likely than female subjects to have a positive DFA (OR 1.8; 95% CI 1.1-2.8; P = 0.02). Specimens collected from April to October were less likely to have a positive DFA (OR 0.4; 95% CI 0.2-0.7; P = 0.001). Specimens collected at the time of hospital admission and during a hospitalization were less likely to have a positive DFA (OR 0.5; 95% CI 0.3-0.9; P = 0.01 and OR, 0.07; 95% CI 0.02-0.2; P = 0.001, respectively) compared with specimens collected in the outpatient setting.


CONCLUSIONS
The yield of testing children without respiratory tract illness is extremely low.
Greenhow
Tara L
TL
Department of Pediatrics, Division of Infectious Diseases, University of California San Francisco, San Francisco, CA, USA. tlgreenhow@aol.com
Weintrub
Peggy Sue
PS
D000208:Acute Disease; D000914:Antibodies, Viral / Q000032:analysis; D001992:Bronchoalveolar Lavage Fluid; D016022:Case-Control Studies; D002675:Child, Preschool; D016001:Confidence Intervals; D005069:Evaluation Studies as Topic; D005260:Female; D019085:Fluorescent Antibody Technique, Direct / Q000379:methods / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015999:Multivariate Analysis; D009305:Nasopharynx / Q000382:microbiology / Q000821:virology; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011336:Probability; D012141:Respiratory Tract Infections / Q000175:diagnosis* / Q000821:virology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014777:Virus Diseases / Q000175:diagnosis*
D000914:Antibodies, Viral