Haemophilus aegyptius

Haemophilus influenzae biogroup aegyptius
Scientific classification
Kingdom:	Bacteria
Phylum:	Proteobacteria
Class:	Gammaproteobacteria
Order:	Pasteurellales
Family:	Pasteurellaceae
Genus:	Haemophilus
Species:	H. influenzae
Trinomial name
Haemophilus influenzae biogroup aegyptius Brenner et al., 1988

Haemophilus influenzae biogroup aegyptius (Hae) is a causative agent of acute and often purulent conjunctivitis, more commonly known as pink eye. It was discovered independently by Koch and Weeks in the 1880s.

During the mid-1980s to early 1990s, a highly virulent clonal group of Haemophilus aegyptius, localized in and around the São Paulo State of Brazil, was found to be responsible for Brazilian purpuric fever, an acute septicemic fulminant illness affecting children.

Haemophilus aegyptius was first observed by Koch in 1883. Under the German Cholera Commission of Egypt, Koch studied 50 patients in Egypt who were suffering from Egyptian eye disease. He discovered this disease was caused by two bacteria. The first, and more serious strain was caused by a “gonococcus-like organism.” H. aegyptius was the more benign form, however at this point it had not been named. Three years later, Weeks published a paper detailing the essential characteristics of H. aegyptius (see “Characteristics” section below).

Neither Koch nor Weeks gave a name for this bacterium, choosing instead to refer to it in relation to the disease it was causing; Weeks’ paper called it “the bacillus of acute conjunctival catarrh.” In 1889, in the first classification treatise naming bacteria under the Latin binomial system, Trevisan listed it as “Bacillus aegyptius.” In the United States, it was listed in 1923 in Bergey’s Manual of Determinative Bacteriology as “Hemophilus conjuntivitidis.” It was listed as “Hemophilus aegyptius” for the first time in the seventh edition of Bergey’s Manual after Pittman and Davis explored and described the characteristic differences between this bacterium and H. influenzae.

In 1892, Pfeiffer discovered H. influenzae, raising some confusion over whether H. aegyptius was different from H. influenzae. Debate has occurred for more than a century. Pittman, who first gave this bacteria its modern name, felt that these bacteria had enough dissimilarities to be considered a separate species. Others, like Brenner et al. stand by a historical viewpoint that the two species are one and the same, with H. influenzae being the older name, and thus the name with higher priority. These bacteria are curious in that they are phylogenetically one species but differ phenotypically; they share the same historical pattern but have clinical differences. Today, the issue remains unresolved, although scientists have put in a lot of effort to classify this bacteria. So far, no one test standing alone has been able to differentiate these two bacteria; however, through compound efforts of different scientists and different tests scientists have gained a greater understanding of the relationship between these two bacteria. In order to account for both the similarities and differences, H. aegyptius has been classified as a biogroup of H. influenzae.

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