Antimicrobial susceptibility pattern in strains of contaminating mycoplasmas in cell cultures

Abstract

Antibiotics are used in the control of mycoplasma contaminations in cell cultures. The antimicrobial resistance of these microorganisms has increased considerably in recent years and the antibiotics of choice, such as quinolones, aminoglycosides and tetracyclines, have become less effective. The aim of this work was to determine the susceptibility patterns in strains of mycoplasma contaminants in cell cultures. Eleven mycoplasma strains, derived from the diagnosis of contamination in cell cultures and previously characterized by biochemical and genetic tests, were used for this purpose. It was determined the Minimum Inhibitory Concentration (MIC) of strains against nine antimicrobial agents used in the routine work with cell cultures and against contaminating mycoplasma species. Isolates showed susceptibility to tetracyclines: minocycline (MIC range: 0.25-0.5 μg/mL) and oxytetracycline (MIC range: 1-2 μg/mL), and to macrolide: tylosine (MIC range: 0.25-1 μg/mL); while they showed moderate resistance to quinolones: enrofloxacin (MIC range: 4-8 μg/mL) and ciprofloxacin (MIC range: 4-8 μg/mL). A total of 10/11 strains showed resistance to aminoglycosides: neomycin (MIC range: 8-16 μg/mL), gentamicin (MIC range: 8-32 μg/mL), kanamycin (MIC range: 8-32 μg/mL), and streptomycin (MIC range: >64 μg/mL). The antimicrobial resistance of mycoplasmas should be continuously monitored with a view to minimizing changes in susceptibility and maintaining antimicrobial efficacy against contamination.