Macrolides and Lincomycin Susceptibility of Mycoplasma hyorhinis and Variable Mutation of Domain II and V in 23S Ribosomal RNA

Abstract

A total of 151 strains of Mycoplasma hyorhinis isolated from porcine lung lesions (weaned pigs, n = 71, and finishers, n = 80) were investigated for their in vitro susceptibility to 10 antimicrobial agents. Thirty-one strains (28 from weaned pigs and 3 from finishers) showed resistance to 16-membered macrolide antibiotics and lincomycin. The prevalence of the 16-membered macrolide-resistant M. hyorhinis strain in weaned pigs from Japanese herds has approximately quadrupled in the past 10 years. Several of the 31 strains were examined for mutations in the 23S ribosomal RNA (rRNA). All field strains tested showed a transition of A to G at position 2059 of 23S rRNA-rendered Escherichia coli. On the other hand, individual tylosin-and lincomycin-resistant mutants of M. hyorhinis were selected in vitro from the susceptible type strain BTS7 by 3 to 9 serial passages in subinhibitory concentrations of each antibiotic. The 23S rRNA sequences of both tylosin and lincomycin-resistant mutants were compared with that of the radical BTS7 strain. The BTS7 mutant strain selected by tylosin showed the same transition as the field-isolated strains of A2059G. However, the transition selected in lincomycin showed mutations in domains II and V of 23S rRNA, G2597U, C2611U in domain V, and the addition of an adenine at the pentameric adenine loop in domain II. The strain selected by lincomycin showed an additional point mutation of A2062G selected by tylosin. KEY WORDS: antimicrobial susceptibility, macrolide resistance, Mycoplasma hyorhinis, 23S ribosomal RNA, tylosin. J. Vet. Med. Sci. 67(8): 795-800, 2005 Mycoplasma hyorhinis, which causes arthritis, pleuritis, peritonitis, pericarditis, and polyserositis, is frequently isolated from the upper respiratory tract and tonsils of young pigs [3, 4]. It is also reported as a causal agent of otitis media [13]. It has often been isolated from pigs with por-cine reproductive and respiratory syndrome (PRRS) [8, 19]. No vaccines have been available to control the spread of M. hyorhinis within herds. Thus, at present, chemotherapeutic control is the most practical way to minimize the economic losses caused by M. hyorhinis infection. There have been several reports examining the susceptibility of M. hyorhinis to antimicrobial agents [1, 2, 6, 9, 10, 20, 24]. Over the course of a decade in Japan, we detected isolates of M. hyorhinis and M. hyosynoviae that were resistant to 16-membered macrolides, such as tylosin and josamycin [9, 10]. A few reports describe macrolide resistance in swine mycoplasmas in European countries [1, 6]; however, no macrolide-resistant M. hyorhinis has been detected in the US. [24]. Alterations in the ribosomal proteins of L4 and L22 [16, 23] and rRNA [22] have been reported as the mechanism of resistance to macrolides in Escherichia coli. In addition, structural modifications of erythromycin by phosphorylation [14], glycosylation [7], and lactone ring cleavage by erythromycin esterase [15] have been reported as the mechanisms of resistance of many bacterial species to e...

Mutations Associated with Decreased Susceptibility to Seven Antimicrobial Families in Field and Laboratory-Derived Mycoplasma bovis Strains

“…Alteration of position 2448 in tiamulin resistant MYC53 lead to decreased susceptibility to florfenicol and pleuromutilins, and the importance of position 2447 in pleuromutilin resistance was previously described in M. gallisepticum. Previous studies have described the substitution C2611G in domain V of M. pneumoniae and the G2597U and C2611U mutations of M. hyorhinis, confirming their effect on 50S inhibitor resistance (36,38). The effects of polymorphisms at positions 171 and 316 have not been clarified yet.…”

“…The acquisition of resistance in M. bovis is generally due to the emergence and spread of a single clone decreasing the genetic heterogeneity of antimicrobial-resistant M. bovis isolates (10,17). The resistant isolates occurring in Hungary harbored the alteration of a neighboring position (position 2059) in rrl genes, an important position in macrolide resistance also (9,35,36,39) Pleuromutilins are used mainly in veterinary practice, especially in swine and poultry, but valnemulin also proved to be effective in calves infected with M. bovis (40). This antimicrobial group binds to the peptidyl transferase center and also inhibits the peptide bond formation and protein synthesis.…”

“…The E. coli nucleotide number is indicated in the column subheadings. *, Altered positions related to high MICs to macrolides in M. bovis (9); †, positions related to high MICs to macrolides and lincomycin in other Mycoplasma species (33,(35)(36)(37)(38); ‡, neighboring mutated positions already described in Mycoplasma gallisepticum (39) and in other bacterial species related to phenicol and pleuromutilin resistance (44,46). b PG45, M. bovis reference strain NCTC 10131 (MIC ϭ 0.5 g/ml [tylosin and tilmicosin] and MIC ϭ 1 g/ml [lincomycin]); MYC52-53, MIC ϭ 0.5 g/ml (tylosin and tilmicosin) and MIC Յ 1 g/ml (lincomycin); MYC2,42,65-76, MIC Ն 128 g/ml (tilmicosin), MIC Յ 32 g/ml (tylosin), and MIC Յ 2 g/ml (lincomycin); MYC22,30,43-51,77-84, MIC Ն 128 g/ml (tylosin and tilmicosin) and MIC Ն 64 g/ml (lincomycin).…”

Bovine mastitis outbreak in Japan caused by methicillin-resistant Staphylococcus aureus New York/Japan clone

“…2,4 As for antimicrobials for which the breakpoints are not established (DCX, NF, OTC, TS, and OA), the bullet value of the bimodal distribution of each antimicrobial was defined as the breakpoint. 24 Reference strain S. aureus ATCC 29213 served as the assay control. Of tested antimicrobials, acceptable quality control ranges of 4 antimicrobials (DCX, NF, OTC, and OA) are not established, 4 therefore MICs of all tested antimicrobials for S. aureus ATCC 29213 in our study are listed in Table 1 for subsequent judgment of quality control.…”

Multilocus Sequence Typing of Mycoplasma hyorhinis Strains Identified by a Real-Time TaqMan PCR Assay

“…These lung diseases result in financial losses due to poor growth performance, reduced feeding efficiency, and higher medication costs and have an adverse effect on pig welfare (4). Moreover, the administration of antimicrobials may have a potential negative effect on human health when associated with food-borne contamination by resistant pathogens (even if M. hyorhinis is generally susceptible to the antibiotics used against M. hyopneumoniae) or resistant commensal bacteria (6).…”