MOLECULAR CHARACTERIZATION SOME BACTERIAL PATHOGENS CAUSING BOVINE MASTITIS WITH SPECIAL REFERENCE TO Mycoplasma bovis

Abstract

In dairy industry, bovine mastitis is the most prevalent disease, which reduces milk production and causes economic losses. This study was conducted to estimate the prevalence of Mycoplasma bovis and some bacteria causing mastitis in dairy farms and partial sequencing of 16SrRNA target genes and Quinolones Resistance Determining Regions (QRDRs) (gyrA and parC) in M. bovis isolates. 370 milk samples were obtained from farms located in villages in Fayoum governorate, Egypt. The examined milk samples (8,91%) were positive for the California mastitis test (CMT). Multiplex RT-PCR was used for the recognition of microorganisms causing mastitis (Staphylococcus (S.) aureus, Streptococcus species (spp.), Escherichia (E.) coli, and Mycoplasma (M.) bovis) from mastitic milk. The results revealed that E. coli was the most predominant (84.8%) followed by S. aureus (81.8%) while M. bovis was the lowest one (51.5%). Mixed infection with two or more mastitic bacterial agents was also identified. All 33 examined mastitic milk samples were diagnosed with mixed infection with E. coli, S. aureus, Streptococcus spp. and M. bovis (36.36%), E. coli and S. aureus (21.21%), and rephrase E. coli, M. bovis, and Streptococcus spp. (6.06%). The sequence analysis of M. bovis 16SrRNA genes illustrated a high similarity of examined isolates to strains previously deposited in the GenBank recovered from the same locality. The gyrA amino acids showed no substitution but showed 100% similarity with M. bovis isolates worldwide. However, the amino acid sequence of parC, showed substitution at positions 2 (Gln to Arg) (CAG >>CGT), 75 (Ile to Ser) (ATT>>AGC), and 79 (Asn to Asp) (AAC>>GAT). Sequence results can lead to the creation of appropriate treatment and control measures for M. bovis, while multiplex RT-PCR, can be exploited as a standard diagnostic method for major mastitis pathogens.