Short communication: In vitro antimicrobial susceptibility of Mycoplasma bovis isolates identified in milk from dairy cattle in Belgium, Germany, and Italy

Abstract

The objective of this study was to assess the in vitro antimicrobial susceptibility of 73 isolates of Mycoplasma bovis isolated from milk of dairy cattle herds of Belgium, Germany, and Italy. Minimal inhibitory concentration (MIC) values were determined by the microbroth dilution method for the following antimicrobials: erythromycin, spiramycin, tilmicosin, tylosin, lincomycin, enrofloxacin, doxycycline, oxytetracycline, florfenicol, and tiamulin. Macrolides, florfenicol, oxytetracycline, and enrofloxacin, were chosen because they represent antimicrobials families commonly used in several countries for treatment of M. bovis, and their MIC values in cattle population are reported in several studies, allowing a comparison with previous data. Doxycycline and tiamulin were selected to assess the susceptibility of M. bovis to new antimicrobials, because they are not registered in the European Union for the treatment of dairy cattle. Among the agents of the different antimicrobial classes, the macrolides showed the highest concentration to inhibit 90% of isolates (MIC90), all above the highest concentration tested: >8μg/mL for erythromycin, >16μg/mL for spiramycin, and >32μg/mL for tilmicosin and tylosin. Also the MIC90 of lincomycin was above the highest concentration tested (>32μg/mL), but the distribution of the MIC values was almost perfectly bimodal: 41 isolates had a MIC ≤0.5μg/mL and 30 isolates >32μg/mL. Oxytetracycline had a 2-fold higher concentration to inhibit 50% of isolates (2 vs. 0.5μg/mL) and 1-fold higher MIC90 (4 vs. 2μg/mL) than doxycycline. Enrofloxacin and florfenicol had both a MIC90 of 2μg/mL, whereas tiamulin had a MIC90 of 0.5μg/mL. Significant differences on the MIC values were found among the 3 countries for several antimicrobials: compared with Germany, Belgium and Italy showed significantly higher MIC for lincomycin, spiramycin, and tylosin, and lower for oxytetracycline and florfenicol. The Belgian isolates showed the lowest MIC for enrofloxacin compared with Germany and Italy. The MIC results obtained in our study suggest the presence of a high level of resistance of M. bovis isolates originating from milk to macrolides in all countries involved in this study. On the contrary, a low level of resistance was found against the antimicrobials that are not used in cattle, such as tiamulin and doxycycline, highlighting a possible link between antimicrobial treatments and development of resistance in the studied M. bovis population.

Emerging Antibiotic Resistance in Mycoplasma Microorganisms, Designing Effective and Novel Drugs / Therapeutic Targets: Current Knowledge and Futuristic Prospects

“…It is interesting to note that the antibiotics to which the entities are usually sensitive may prove to be ineffective due to development of resistance 97 . Recently a number of studies have been carried out for evaluating antibiotic sensitivity of mycoplasma species against antimycoplasma antibiotics 98,99,100,101,102 . The antibiotics under focus included enrofloxacin, marbofloxacin, melittin, gramicidin D, spiramycin, tulathromycin, erythromycin , tylosin, florfenicol, oxytetra-cycline, doxycycline, tilmicosin, lincomycin, tiamulin, gamithromycin, tildipirosin and valnemulin 98,99,100,101,102 .…”

AntibioticScout.ch: Decision support for the prudent use of antimicrobials: Application in cattle

“…Dieses Antibiotikum aus der Gruppe der Phenicole besitzt eine ausreichende Gewebepenetration, ein sehr breites Wirkspektrum, ein grosses Verteilungsvolumen und zeigt gegen die häufigsten Erreger der EBP (inkl. Mykoplasmen) eine gute Wirkung; Resistenzen wurden bisher wenig beobachtet (Bäumer, 2012;Gautier-Bouchardon et al, 2014;Sulyok et al, 2014;Barberio et al, 2016). Als "second line" empfiehlt AntibioticScout.ch die Anwendung von Sulfonamiden in Kombination mit Trimethoprim.…”

The status of Mycoplasma bovis infection in clinical mastitis cases in China

“…), Belgium, and Germany and Italy (Barberio et al . ). Investigations of the pathogen in clinical cases of mastitis in China are also limited.…”

“…However, because as many as 25% of clinical and 40% of subclinical mastitis cases were not detected, cases of mastitis caused by M. bovis were completely undiagnosed in Europe and Israel (Bradley et al 2007;Lysnyansky et al 2016). To date, outbreaks of mastitis attributed to M. bovis have been reported in Denmark (Nielsen et al 2015), Northern Greece (Filioussis et al 2007), the Netherlands (Heuvelink et al 2016), Australia (Schibrowski et al 2018, Switzerland (Aebi et al 2015), Belgium, and Germany and Italy (Barberio et al 2016). Investigations of the pathogen in clinical cases of mastitis in China are also limited.…”