Brazilian purpuric fever: fast characterization of invasive Haemophilus aegyptius

Strains of H. aegyptius isolated during outbreak of Brazilian Purpuric Fever (BPF) in Brazil were characterized antigenically by slide agglutination test utilizing antiserum produced with a H. aegyptius strain isolated from blood culture from a patient with BPF. By means of this method, it were identified H. aegyptius strains responsible for outbreaks of conjunctivitis with identical antigenic characteristics to strains isolated from BPF. The sensitivity and specificity of slide seroagglutination test was 97.7% and 89.6% respectively; therefore this assay was efficient to be used as a screening method in the studies of purulent conjunctivitis for detecting high risk populations for BPF, and to implement measures that will increase the efficiency of epidemiologic surveillance.