Detection of antigenuria for diagnosis of invasive Haemophilus influenzae type b disease.

BACKGROUND

Haemophilus influenzae type b (Hib) diseases are responsible for an estimated 400,000 childhood deaths, mostly in developing countries.

OBJECTIVES

To determine the value of the Wellcogen quantitative latex agglutination test (LA) in urine for the diagnosis of Hib pneumonia and meningitis.

METHODS

Healthy and sick children aged <5 y were enrolled in Dhaka Shishu (Children's) Hospital. Boiled and non-concentrated urine specimens underwent LA testing. In vaccinated subjects, urine was tested by LA at 24 h, 4-6 and 7-10 d after vaccination.

RESULTS

Of 1302 enrolled cases, 201 were healthy (90 Hib vaccine recipients and 111 provided NP) and 1101 were sick with either pneumonia (n=974) or meningitis (n=127). Among the healthy children enrolled, 41 (41/111, 37%) were colonised with Hib and two (2/41, 5%) were positive by LA test. Hib antigenuria among the children who had received Hib vaccination was mainly detected only on day 1 (7/90, 8%) of vaccination. Among the sick children, LA test for Hib antigen was positive for all confirmed cases of Hib pneumonia (10) and meningitis (35). In contrast, none of the urine specimens from the cases with a known aetiology other than Hib (n=104) was positive. Quantitative analysis of antigenuria of sick children showed that it is positive at least up to 1:8 and 1:16 dilutions for pneumonia and meningitis, respectively, in contrast with <or=1:4 for healthy children. In addition to the ten cases of culture-proven Hib, the test detected an additional 16 Hib pneumonia cases among children diagnosed as pneumonia, based on the presence of antigenuria >or=1:8 dilutions.

CONCLUSIONS

The Wellcogen LA test for Hib using boiled and non-concentrated urine is more sensitive than blood culture alone and is highly specific.