Antibiotic sensitivity and mutation rates to antibiotic resistance inMycoplasma mycoidesssp.mycoides

Abstract

SUMMARYThe antibiotic resistance ofMycoplasma mycoidesssp.mycoidesstrain T1was investigated. This strain was resistant to high levels ( > 100 μg ml−1) of rifampicin and nalidixic acid. It was sensitive to streptomycin, spectinomycin and novobiocin; however, single step mutants with high levels of resistance ( > 100 μg ml−1) were readily isolated. With erythromycin and tylosin for which the minimum inhibitory concentration (MIC) for the parent strain was < 0·1 μg ml−1, mutants resistant to > 100 μg ml−1were obtained in two and three steps respectively. The MIC of tetracycline in single step resistant mutants (0·6 μg ml−1) was tenfold higher than the parent strain, but could not be increased further. There was only a twofold increase in resistance to chloramphenicol in single step mutants. The frequency of resistant mutants varied with the antibiotic and was between 4× 10minuss;6and 2× 10−8. The mutation rate to antibiotic resistance to streptomycin, spectinomycin, novobiocin, erythromycin and tylosin was between 3× 10−8and 5× 10−9per cell per generation. There was a fivefold decrease in mutation rate to resistance to 60 μg ml−1streptomycin compared to that to 20 μg ml−1.

Development of antibiotic resistance inMycoplasma gallisepticum in vitro

“…It is possible that further passages might have increased the resistance but this is considered unlikely in the light of other workers' results. Similar results were obtained by Hannan et al (1997) with M. hyopneumoniae and by Lee et al (1987) with M. mycoides. Osborn et al (1960) reported that strains less sensitive to tetracycline appeared only after prolonged treatment (5 months) of chickens with a very high dosage in the feed (1000 g/ton).…”

Direct transfer of whole genomes from bacteria to yeast

“…Finally, whole-genome sequencing revealed only one new mutation in the genomes of these transplants relative to the genome sequence determined with a population of cells before cloning and genome transfer into yeast. This frequency is consistent with the mutation rate of Mycoplasma 20 . Therefore, it is likely that no mutation in these genomes is attributed to our transfer procedure ( Supplementary Note 1 ).…”

Evolutionary History of Contagious Bovine Pleuropneumonia Using Next Generation Sequencing of Mycoplasma mycoides Subsp. mycoides “Small Colony”

“…In bacteria, mutation rate has been estimated for decades in vitro by detecting phenotypic traits that depend on SNPs, such as antibiotic resistance. The in vitro mutation rate for mycoplasmas is similar to that of other bacteria [33]. This finding is surprising since mycoplasmas lack the methylation-mediated DNA repair system commonly found in other bacteria whose genome has not been drastically reduced in size.…”