Pneumonia are one of the important problems in cattle breeding. Mycoplasmas are detected at a significant rate among the agents of pneumonia, and the most common among them is M. bovis. Pneumonia cases caused by mycoplasmas have been reported for different years
14, 18, 28.
In studies conducted in various countries, differences in M bovis isolation rates from pneumonia cases were observed. It has been reported that M. bovis is isolated in 11.8% in Hungary 29, 13-23% in Ireland 30, 31, 25% in Italy 32, 30% in France 7 and 91% in Canada 33.
In various studies conducted in different regions of Türkiye, it is reported that the isolation rate of M. bovis varies between 4% and 81.3% 21, 28, 34-36.
In this study, a total of 100 bovine lung samples were examined by molecular and cultural methods. Out of 52 (52%) examined samples were found positive for M. bovis by real time PCR. In studies on the prevalence of M. bovis in various countries (11.8-91%) and Türkiye (4-81.3%), it has been reported that it can be isolated at different rates. The results obtained in this study are similar to the isolation rates obtained in both Türkiye and other countries. In particular, isolation by molecular or bacteriological culture method may cause proportional differences since the sensitivity of molecular methods is higher than the bacteriological culture method.
Since the host defense system is weakened in M. bovis infections, a predisposing situation may occur in terms of secondary pathogens. In studies of mixed infections, Arcangioli et al. 37 stated that M. bovis was detected in the early stage of pneumonia and M. bovis may be the primary or predisposing factor in the formation of bovine respiratory disease outbreaks.
Haines et al. 26 reported that they detected M. bovis antigen by immunohistochemical method in the 35 lungs and the 22 joints of 49 cattle with chronic pneumonia that did not respond to treatments. They reported that out of M. bovis antigen positive cases, 39% were BVDV, 10% H. somni, 20% M. haemolytica, and 12% vere found to be both BVDV and M. haemolytica antigen positive.
Bacterial agents isolated together with M. bovis include M. haemolytica, P. multocida, Trueperella pyogenes and less frequently H. somni, and viral agents such as bovine respiratory syncytial virus, BHV-1 and BPIV-3. agents are reported 38. Brice et al. 30 also stated that they isolated 20.5% M. haemolytica, 9.06% T. pyogenes and 8.36% P. multocida in 287 animals with positive M. bovis. Şahin 34 isolated various mycoplasma species (6 M. bovis, 4 M. bovirhinis and 2 M. arginine) from 12 of 109 cattle lungs with pneumonia. Seven of them were P. multocida, M. haemolytica and Staphylococcus spp. reported positive. Byrne et al. 31 reported that in 66% of the M. bovis positive cases they detected in Ireland, they also detected viral agents such as BHV-1 and BPIV-3, as well as other bacteria such as P. multocida and M. haemolytica.
Various bacterial agents were detected by culture method in 50 of 100 lung samples examined in this study. While 9 of the culture positive samples contained more than one agent, only one agent was isolated from 41 of them. Different species and numbers of bacteria were detected in 23 of 52 samples found positive for M. bovis by real time PCR. While 2 different bacteria were detected in 3 of them, a single bacterium was isolated and identified in the other 20. In this study, bacterial culture positivity was detected in 23 of the samples found positive for M. bovis by real time PCR. Out of 23 M. bovis positive samples, E. coli from 8, P. multocida from 5, M. haemolytica from 3, K. pneumonia from 3, S. paucimobilis from 3, and Staphylococcus spp. from 1 sample were isolated and identified. Among these samples, E. coli was also isolated and identified in 2 K. pneumonia and 1 S. paucimobilis positive samples. Various bacterial agents were isolated by culture method from 27 of 48 lung samples that were negative for M. bovis by real time PCR. A single agent was isolated in 21 of the samples that were positive for bacteriological culture. More than one agent was isolated in 6 of them.
In studies on the subject, it was observed that other pathogens isolated from M. bovis positive animals showed similarities with the isolated strains in this study. As can be seen, suppression of the immune system in pneumonia cases and other predisposing factors that develop in the tissues provide an environment for the inclusion of secondary factors. The existence of multifactorial pneumonia cases observed in other studies was once again demonstrated in this study.
The results obtained in this study show that M. bovis is a common and important (52%) pneumonia agent in southern Türkiye. In the study, different types and numbers of bacteria were isolated in 44.2% of the samples that were positive for M. bovis by real time PCR, while 2 different bacteria were isolated and identified in 3 of them, and a single bacterium was isolated and identified in the other 20. In such studies, it is very difficult to determine the primary factor. On the other hand, the inability to detect different agents in M. bovis positive samples increases the possibility of M. bovis being the primary agent.
It was concluded that the high rate of M. bovis positivity in the study was due to the real time PCR method, which is shown as a reference method among diagnostic methods in the literature and used in this study.
As a result, pneumonia cases are frequently seen in cattle in Türkiye as well as all over the world and cause significant economic losses in many regions. For this reason, pneumonia cases are an important problem that should be carefully considered. In the prevention of disease, business management errors, negative care conditions and stress factors should not be ignored in terms of herd management.