Provisional identification of haemophilus influenzae from sputum cultures within one hour by rapid enzyme test

ABSTRACT

In this study, Identification of possible H. Influenzae Isolates from cultures of sputum samples by a 5 min test for production of indole and Beta-galactosidase followed by 1 h porphyrin test was compared with tests for dependence on[X] and [V] factors. A commercially produced form of the rapid tests [Haemstrip Lab. M. Bury, Lancs] was used. The study was conducted on 300 patients with respiratory symptoms from Banha and Zagazig University Hospitals where 75 potential Haemophilus colonies from cultures of sputum samples on heated blood agar incubated in humified atmosphere with CO[2] were identified. When the results of the two tests were in disagreement, both tests were repeated. Colonies that were Beta-galactosidase positive after 5 min were considered to be non H. lnfluenzae and those that were Beta-galactosidase negative but indole positive were considered to be H. Influenzae. At this stage the test had a sensitivity of 85.3% and specificity of 85.7%. After 1 h, only colonies that were Beta-galactosidase and porphyrin negative were considered to be H. Influenzae, the sensitivity was then 100% and specificity 100%. Accordingly, Haemstrip results may permit provisional identification of H. influenzae, a potential pathogen of the lower respiratory tract, after overnight culutre of primary isolation plate