  Antibiotics resistance has caused much complication in the treatment of
diseases, where the pathogen is no longer susceptible to specific antibiotics
and the use of such antibiotics are no longer effective for treatment. A recent
study that utilizes digital organisms suggests that complete elimination of
specific antibiotic resistance is unlikely after the disuse of antibiotics,
assuming that there are no fitness costs for maintaining resistance once
resistance are established. Fitness cost are referred to as reaction to change
in environment, where organism improves its' abilities in one area at the
expense of the other. Our goal in this study is to use digital organisms to
examine the rate of gain and loss of resistance where fitness costs have
incurred in maintaining resistance. Our results showed that GC-content based
fitness cost during de-selection by removal of antibiotic-induced selective
pressure portrayed similar trends in resistance compared to that of no fitness
cost, at all stages of initial selection, repeated de-selection and
re-introduction of selective pressure. Paired t-test suggested that prolonged
stabilization of resistance after initial loss is not statistically significant
for its difference to that of no fitness cost. This suggests that complete
elimination of specific antibiotics resistance is unlikely after the disuse of
antibiotics despite presence of fitness cost in maintaining antibiotic
resistance during the disuse of antibiotics, once a resistant pool of
micro-organism has been established.
