Serotypes and antibiotic sensitivity of Moraxella bovis isolated from an outbreak of infectious bovine keratoconjunctivitis

Samples of conjunctival fluid of four calves, from a herd with infectious bovine keratoconjunctivitis, were collected five times at monthly intervals and from another 16 calves in the initial stages of the disease, were collected only once. Moraxella bovis was recovered from 82.3% of the samples. Twenty-six isolates were typed with polyvalent sera and 25 with monovalent sera. The antibiotic sensitivity of 13 isolates was also studied. Twenty of the 26 isolates reacted with polyvalent sera and 16 of 25 tested isolates, reacted with monovalent sera. The isolates recovered from the same animal in a different collection or from a different animal in the same collection did not always belong to the same serogroup. Different serotypes were prevalent in each collection. Differences in the antibiotic sensitivity of the isolates were also detected.