A total of 90 strains of Mycoplasma hyopneumoniae from 70 farms in 10 prefectures, collected between 2004 and 2005, were investigated to determine in vitro susceptibilities to nine drugs that are considered effective antimicrobial agents for mycoplasmas. Seven strains were found resistant to 16-membered macrolide antibiotics and lincomycin. All resistant strains had point mutations either at A2058G (five strains) or A2058G and A2062C (two strains) in 23S rDNA. Strains possessing two mutations showed higher resistance to tylosin than those with one mutation. Focusing on the mutation in 23S rDNA, we developed a rapid detecting technique using HR-1TM and LC-Green ITM for the screening of macrolide-resistant M. hyopneumoniae. This technique is based on detection of a point mutation in a limited region of 23S ribosomal RNA. It took four hours to yield a result when a strain was harvested, compared to eight hours when a lung lesion sample was examined.
(Center for Animal Diseases Control and Prevention, TEL +81-29-838-7708)
