Haemophilus aegyptius
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Proteobacteria, Class Gammaproteobacteria, Order Pasteurellales, Family Pasteurellaceae, Genus Haemophilus,  
Haemophilus aegyptius (Trevisan 1889) Pittman and Davis 1950.

Historical synonyms: Bacillus aegyptius Trevisan 1889, Bacillus conjunctivitidis Kruse 1896, Bacterium conjunctivitis Chester 1897,
Bacterium pseudo conjunctivitidis (Kruse) Chester 1897, Bacterium aegyptiacum Lehmann and Neumann 1899, Hemophilus
conjunctivitidis (Kruse) Bergey et al. 1923. Common name: Koch-Weeks Bacillus.
Gram negative, 0.2-0.3 / 2.0-3.0 µm, piliated, long slender rods,  nonmotile,
nonsporeforming. Capsules have not been demonstrated.
Growth of freshly isolated strains on chocolate agar is slow; colonies are smooth,
low, convex, grayish, translucent, 0.5 mm in diameter in  48h. Forms comet-like
colonies in semisolid agar media. Hemolysis is negative.
Does not grow on Tryptic soy agar Difco with X and V factors added , in contrast to
Haemophilus influenzae.
Aerobic, facultatively anaerobic, require X-factor and V-factor
for growth. CO
2 is not required. Optimum temperature 34-37 ºC. Growth on Mac
Conkey agar was not determined.
Causes acute or subacute infectious conjunctivitis in hot climates. It has not been demonstrated in healthy individuals. Humans are
the only natural host .
Produce an extracellular IgA1-cleaving endopeptidase and have neuraminidase activity. Is piliated. Have hemagglutinating activity.
Causes acute or subacute infectious conjunctivitis in hot climates.
“BPF clones” closely related to
H. aegyptius (H. influenzae biogroup aegyptius) have been associated with Brazilian purpuric fever.
Presents low experimental pathogenicity for mouse and higher for 8-days chicken embryos.
  1. Mogens Kilian, 2004.Genus III. Haemophilus . In:  Bergey’s Manual of Systematic Bacteriology, Second edition,Vol two, part B,
    George M. Garrity (Editor-in-Chief),   pp. 883-904.
  2. Mary P.E. Slack, 2006.Haemophilus. In: Topley & Wilson’s Microbiology and Microbial Infections, 10 edition, Vol. 2, Bacteriology,
    Edward Arnold Ltd.
  3. Pozsgi N., 1985. Genul Pasteurella. In: Bacteriologie medicala, vol II, v. Bilbiie, N. Pozsgi (sub redactia), Ed. Medicala, Bucuresti,
    123-130.
  4. Margaret Pittman & Dorland J. Davis: IDENTIFICATION OF THE KOCH-WEEKS BACILLUS (HEMOPHILUS AEGYPTIUS). J.
    Bacteriol. 59 (3): 413.
Nitrates reduction, oxidase, alkaline phosphatase, catalase & urease are positive.
Acid production from D(+) glucose, D(+) galactose & maltose is weak.

H
2S, arginine dehydrolase, lysine decarboxylase, ornithine decarboxylase, indole, glycerol, xylitol, L(+) arabinose, dulcitol, meso-
inositol, mannitol, D(-) sorbitol, D(-) fructose,  D(+) mannose, L(+) rhamnose, L(-) sorbose, cellobiose, lactose, ONPG, D(+)
melibiose,
sucrose (saccharose), trehalose, raffinose, inulin,  D(+) xylose, esculin, salicin, α-glucosidase (PNPG) & gas from D(+) glucose are
negative.
(c) Costin Stoica
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