Blood broth: Slightly turbid. No hemoly- sis. Litmus milk with blood: Rendered very slightly alkaline by some strains. Sterilized potato slant: No growth. Fresh, unheated, sterile potato added to broth favors development. Indole is produced by some strains. Various carbohydrates are attacked by some strains, provided a suitable medium is used, while other strains do not attack any of the carbohydrates. Mannitol and lactose are never fermented. Nitrites produced from nitrates. Aerobic, facultatively anaerobic; CO2 may favor primary isolation. Temperature relations: Optimum, 37° C. Minimum, between 25° and 27° C. Maxi- mum, 43° C. Killed in thirty minutes at 55° C. Pathogenic; strains may or may not be encapsulated. Six serological types (a-f) of Haemophilus influenzae are recognized on the basis of precipitation of immune serum by capsular substance. Strains from cerebrospinal fluid are usually of type b. The majority of the strains from the respiratory tract are not type-specific, but they may cause infec- tion. Source : Isolated by Pfeiffer from cases of influenza; also found in the nasopharynx, in sputum, sinuses, conjunctiva, cerebro- spinal fluid, blood and in pus from joints. Habitat: Found in the respiratory tract. A cause of acute respiratory infections, of acute conjunctivitis and of purulent menin- gitis of children, rarely of adults. Regarded by Pfeiffer and by others to be the cause of influenza. 2. Haemophilus aegyptius (Trevisan, 1889) Pittman and Davis, 1950. (Koch, Wiener med. Wochnschr., 33, 1883, 1550; reprinted in Arb. a. d. kaiserl. Gesund- heitsamte, 8, 1887, Anlage 2, 19; Weeks, Arch. Ophthalmol., 15 (old series), 1886, 441; also see New York Med. Record, 31, 1887, 571; Bacillus aegyptius Trevisan, I generi e le specie delle Batteriacee, 1889, 13; Bacterium aegyptiacum Lehmann and Neumann, Bakt. Diag., 2 Aufl., 3, 1899, 191; Hemophilus conjunctivitidis Bergey et al.. Manual, 1st ed., 1923, 270; Pittman and Davis, Jour. Bact., 59, 1950, 413.) ae.gyp'ti.us. L. adj. aegyptius Egyptian. Common name: The Koch-Weeks Bacil- lus. Rods, 0.25 to 0.5 by 1.0 to 2.5 microns, occurring singly, occasionally in short chains and at times in the form of threads. Show bipolar staining. Non-motile. Gram- negative. Requires both the factors V and X for growth. Blood agar colonies: Very small, circular, transparent, homogeneous, entire. No hemolysis. Satellitism with Micrococcus. V and X transparent agar colonies: 1 to 2 mm in diameter, bluish sheen in trans- mitted light. V andX broth: Turbid. Indole not produced. Weak acidity but no gas from glucose, fructose and galactose. No acid from xylose, maltose, sucrose, lactose or mannitol. Nitrites produced from nitrates. Aerobic, facultatively anaerobic. Optimum temperature, between 34° and 37° C. Growth range, 25° to 40° C. Pathogenic for man. Serologically homogeneous or closely related to, and distinct from, Haemophilus influenzae. Agglutinates human red blood cells. Source: Isolated from conjunctiva. Habitat: Causes acute or subacute infec- tious conjunctivitis in warm climates. 3. Haemophilus suis Hauduroy et al., 1937. (Hemophilus influenzae suis Lewis and Shope, Jour. Exp. Med., 54, 1931, 361; Hauduroy et al.. Diet. d. Bact. Path., 1937, 258.) su'is. L. noun sus a hog, swine; L. gen. noun suis of swine. Morphologically resembles Haemophilus influenzae. Requires both the factors V and X for growth (Lewis and Shope, op. cit., 1931, 361). Requires V but not X; serum added to Levinthal agar stimulates growth (Alexan- der, in Dubos, Bacterial and Mycotic Infections of Man, 2nd ed., 1952, 528). Blood agar colonies: Very minute. No
