Prevalence and Antimicrobial Susceptibility of Bovine Mycoplasma Species in Egypt

Abstract

Among many bovine Mycoplasma species (spp.), Mycoplasma bovis is recognized as a significant causative agent of respiratory diseases in cattle. In recent years, resistant M. bovis isolates, especially to fluoroquinolones, have been reported globally as a result of the extensive usage of antimicrobials in the treatment of bovine pneumonia. Therefore, the aim of this study is to investigate the prevalence and antimicrobial susceptibility patterns of bovine Mycoplasma spp. isolated from the respiratory tracts of cattle in Egypt and to assess the fluoroquinolones resistance in the recovered mycoplasma isolates via broth microdilution and conventional PCR techniques. Conventional phenotypic methods identified 128 mycoplasma isolates (32%) from 400 different samples, with M. bovis being the predominant spp. (61%), followed by M. bovirhinis (15%). Of note, mycoplasma isolates were rarely isolated from total healthy lung tissues (7/55, 12.7%), but they were frequently isolated from pneumonic lungs (31/45, 68.9%). All the examined mycoplasma isolates (n = 76) were sensitive to tilmicosin, tylosin, tulathromycin, spiramycin, and spectinomycin (100% each), while 60.5% and 43.4% of the examined isolates had high minimum inhibitory concentration (MIC) values to enrofloxacin and doxycycline, respectively. Three and two mycoplasma isolates with high enrofloxacin MICs were confirmed to be M. bovis and M. bovirhinis, respectively, by PCR assays. All molecularly confirmed mycoplasma isolates (n = 5) were positive for the gyrA gene (100%); meanwhile, three isolates (60%) were positive for the parC gene. In conclusion, our findings revealed alarming resistance to enrofloxacin and doxycycline antibiotics; thus, antimicrobial usage must be restricted and molecular techniques can help in the rapid detection of the resistant strains.

Keywords: Mycoplasm bovis; cattle; fluoroquinolone resistance; gyrA; parC.

Figure 1

Prevalence of M. bovis and M. bovirhinis isolates in various samples’ sources (A) and types (B). Ns: nasal swabs, Ts: tracheal swabs, Lt: lung tissues; Tt: tracheal tissues, * p < 0.05, *** p < 0.001, ns: non-significant.

Figure 2

Prevalence rates of enrofloxacin and doxycycline among mycoplasma isolates from different samples’ sources. Ns: nasal swabs, Ts: tracheal swabs, Lt: lung tissue, Tt: tracheal tissue, *** p < 0.001.

Figure 3

Prevalence of molecularly identified Mycoplasma species in the collected samples from different sources. The prevalence rate for each species was calculated regarding the total number of the examined samples from different sources. ns: non-significant, Lt: lung tissue, Tt: tracheal tissue.

Figure 4

Prevalence of gyrA and parC genes in two bovine Mycoplasma species (A) and mycoplasma isolates from different samples’ sources (B). Lt: lung tissue, Tt: tracheal tissue, QRDRs: quinolone resistance-determining regions, ns: non-significant.