[Bacteriological studies of Haemophilus equigenitalis Taylor 1978, the causative organism of contagious equine metritis 1977 (author’s transl)].

This study examines various properties of Haemophilus equigenitalis, a bacteria responsible for a contagious horse disease called equine metritis. The analysis covers its culture, biochemistry, antigens, and reactions to different antibiotics, highlighting the uniqueness of its biochemical profile compared to other bacteria tested.

Investigation of Haemophilus equigenitalis Strains

• The researchers studied 17 strains of Haemophilus equigenitalis, a bacterium known to cause contagious equine metritis, a serious disease in horses.
• Multiple aspects of the bacteria were focused on in this study, including its cultural, biochemical, antigenic, and antibiotic susceptibility characteristics.
• For this purpose, they utilised conventional methods as well as the API ZYM system, a technique developed for the detection of enzymatic activities.

Biochemical Characteristics

• The study found that the biochemical profile of Haemophilus equigenitalis was unique and distinct from the other bacteria, like Haemophilus influenzae, Haemophilus parainfluenzae, Brucella abortus, Brucella melitensis, Pasteurella multocida, and Acinetobacter calcoaceticus, investigated under the same conditions.
• It was observed that the necessary X and V factor requirements weren’t demonstrated by Haemophilus equigenitalis, making its classification within the genus Haemophilus questionable.

Antigenic Homogeneity and Antibiotic Susceptibility

• The research also revealed that there was antigenic homogeneity within the Haemophilus equigenitalis species, meaning that strains of these bacteria had identical antigenic properties. Notably, these strains did not cross-react with other strains tested in the study.
• Antibiotic susceptibility was another crucial aspect covered in this research. Using a diffusion test and minimal inhibitory concentration (MIC) determination, the researchers found that Haemophilus equigenitalis strains were susceptible to almost all tested antibiotics, except for clindamycin, lincomycin, and streptomycin.
• However, of these, streptomycin resistance in the strains was sporadic, meaning it was not consistently present.