VIEW ARTICLE

Genetics

In Vitro Susceptibility and Resistance of Two Spiroplasmas to Antibiotics. C. H. Liao, Assistant research professor, Department of Plant Pathology, Rutgers University—The State University of New Jersey, New Brunswick 08903; T. A. Chen, professor, Department of Plant Pathology, Rutgers University—The State University of New Jersey, New Brunswick 08903. Phytopathology 71:442-445. Accepted for publication 18 September 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-442.

More than 20 antibiotics that inhibit protein and nucleic acid synthesis in bacteria were examined for effectiveness against Spiroplasma citri and the honeybee spiroplasma. Rifampicin, nalidixic acid, actinomycin D, and streptomycin and three of its derivatives were ineffective at concentrations that ordinarily suppress bacterial growth. Aminoglycoside antibiotics that contain a deoxystreptamine moiety, such as kanamycin, neomycin, and gentamicin were highly effective; while those without a deoxystreptamine moiety, such as kasugamycin, hygromycin, and spectinomycin were not. Spiroplasma strains that permanently resist kanamycin (300 μg/ml), neomycin (300 μg/ml), gentamicin (300 μg/ml), chlortetracycline (300 μg/ml), tetracycline-HCl (20 μg/ml), oxytetracycline (10 μg/ml), and erythromycin (100 μg/ml) were selected at low frequencies (10^–9–10^–10). Resistance to kanamycin, neomycin, gentamicin, tobramycin, and paromomycin appeared to be linked, but a linked resistance to different forms of tetracycline was not found.