Haemophilus aphrophilus isolated from the blood of a patient with infective endocarditis

On July 1994, a 62-year-old female, having a history of mitral regurgitation, was admitted because of high fever, hematuria and conjunctival petechiae. She was diagnosed as having infective endocarditis with mitral valve vegetation proved by ultrasonic cardiography. The gram negative rods were isolated from blood cultures performed five times, performed prior to the administration of antibiotics. The isolates were identified as strains of H. aphrophilus. After two days of treatment with PCG (12 million units/day), the organism became undetectable from the blood. Since the minimal inhibitory concentrations (MICs) of PCG and ABPC were ranged between 0.06-2.0 micrograms/ml and 0.06-0.5 microgram/ml, respectively, ABPC was selected as a first choice antibiotic instead of PCG. ABPC was given 12 g/day for the first 3 days, then 6 g/day for 28 days, followed by 3 g/day for 7 days. The patient recovered and was discharged after the 55 hospital days. H. aphrophilus grew on BTB lactose agar, chocolate agar and sheep blood agar, but failed to grow on MacConkey agar. H. aphrophilus produced smooth transparent nonhaemolytic micro colonies after 48 hours on sheep blood agar and chocolate agar plates. Atmosphere with 5% CO2 failed to enhance their growth. All the five strains of H. aphrophilus isolated, required neither factors V nor X. Positive synthesis of porphyrin from delta-aminolevlinic acid confirmed their ability to grow without X factor. For the correct identification of H. aphrophilus strains, fermentation test of glucose, lactose, maltose and sucrose in either phenol red broth or CTA medium are necessary.(ABSTRACT TRUNCATED AT 250 WORDS)