Mycoplasma bovis spreading throughout cattle in Croatia since it first outbreak in 2002

Mycoplasma bovis was first isolated from milk of cows with mastitis in USA. Throughout the years, its significance has also been proved in arthritis, pneumonia, otitis and conjunctivitis in calves. In recent years, M. bovis has been frequently isolated from nasal cavities and/or pneumonic lungs of calves in many countries in North America, Europe, and Asia. The first isolation of M. bovis in Croatia was in year 2002 during the first outbreak of mycoplasma bovine mastitis recorded in the country. Since then milk from cows with history of mastitis from selected large milk farms has been monitored for mycoplasma and M. bovis has been recovered from 209 out of 1764 milk samples examined. Unfortunately the significance of M. bovis in calf pneumonia in Croatia is poorly appreciated, as demonstrated by the low numbers of clinical samples submitted to the Institute for diagnostic investigation. In a preliminary investigation to confirm the contribution of M. bovis to calf pneumonia in Croatia, four farms on which calves from various sources were raised and which had experienced continuous problems with chronic pneumonia were selected for study. Sixty six nasal swabs from 4 farms were collected and examined for the presence of M. bovis using enrichment and capture sandwich ELISA, culture in Hayflick broth and culture on mycoplasma agar. After isolation on solid agar and identification by sELISA, 20 isolates were randomly selected and tested by PCR. M. bovis was detected in 39 out of 74 (52, 7 %) nasal swabs from all 4 farms and 5 out of 11 (45, 5 %) lung samples from 4 farms by enrichment and capture sELISA. All samples positive in sELISA yielded growth of mycoplasma colonies on mycoplasma agar plates. All 20 selected isolates that were previously identified by ELISA were confirmed as M. bovis by PCR.