In vitro evaluation of various antimicrobials against Mycoplasma gallisepticum and Mycoplasma synoviae by the micro‐broth method, and comparison with a commercially‐prepared test system

Abstract

SUMMARYThe efficacy of danofioxacin, a new quinolone antimicrobial agent, was tested in vitro by the micro-broth method with nine field strains of Mycoplasma gallisepticum (Mg) and eight of M. synoviae (Ms) and comparison was made with oxytetracycline and tylosin tartrate. The virulent S6 strain of Mg was also included for reference. All Mycoplasma strains, including a strain of Mg that was resistant to tylosin tartrate, were susceptible to danofioxacin with minimal inhibitory concentrations ranging from £ 0.008 to 0.5 μg/ml. A commercially produced test system (Sensititre®), using micro-plates whose wells were predosed with antimicrobial agents and then dried, was also investigated. Results with the same three antimicrobials were in agreement with those obtained by the micro-broth method. With the exception of the tylosin resistant strain, the Mg strains were more susceptible to erythromycin than the Ms strains. Conversely, Ms strains were susceptible to apramycin, while the Mg strains appeared to be resistant.

Persistence of Mycoplasma synoviae in hens after two enrofloxacin treatments and detection of mutations in the parC gene

“…Although M. synoviae is susceptible in vitro to various antibiotics including enrofloxacin [7,20], persistence after antimicrobial treatments is regularly observed in field conditions [22,35]. This phenomenon has already been described for M. gallisepticum in chickens [33], but successive treatments at the therapeutic dose reduced the percentage of M. gallisepticum-infected birds.…”

“…M. synoviae may be transmitted either vertically, through the eggs, or laterally, by direct contact or via the environment [22,25]. M. synoviae is susceptible to various antibiotics in vitro, including tetracyclines, macrolides (except erythromycin) and fluoroquinolones [7,15]. However, although antibiotic treatments decrease the symptoms, they do not eliminate M. synoviae infections [22].…”

In vitroantibiotic susceptibility of DutchMycoplasma synoviaefield isolates originating from joint lesions and the respiratory tract of commercial poultry

“…The initial MIC was defined as the lowest antibiotic concentration to show no change in colour when the colour of the mycoplasma growth control changed (Hannan, 2000). The final MIC was read when no further colour change was observed (Bradbury et al, 1994;Hannan, 2000).…”

“…However, the antibiotic susceptibility profiles of the mycoplasma strains involved should be determined if treatment efficacy is to be maximized. During the past decades a number of studies describing the in vitro antibiotic susceptibility of M. synoviae strains have been published (Jordan & Knight, 1984;Bradbury et al, 1994;Jordan & Horrocks, 1996;Wang et al, 2001;Cerda et al, 2002). Nevertheless, recent reports on the minimum inhibitory concentrations (MICs) of M. synoviae isolates from European countries are scarce.…”

Development of antibiotic resistance inMycoplasma gallisepticum in vitro

“…Domermuth (1958Domermuth ( , 1960, Osborn et al (1960), Kiser et al (1961) and Zanella (1966) used a number of antibiotics to study, both in vivo and in vitro, how antibiotic resistance was induced in Mycoplasma gallisepticum (Mg). More recently, in vivo and in vitro tests to assess the sensitivity to a wide spectrum of chemotherapeutic agents, particularly tylosin and quinolones, have been carried out on various isolates of Mg (Kleven & Anderson, 1971;Levisohn, 1981;Lin, 1987;Kempf et al, 1989;Jordan et al, 1989;Bradbury et al, 1994;Jordan & Horrocks, 1996).…”