The Journal of Medical Microbiology, Vol 13, Issue 3 411-421, Copyright © 1980 by Society for General Microbiology
Transfer of gentamicin resistance between cultures of Staphylococcus aureus in nutrient broth, serum and urine
R. W. Lacey and V. L. Lord
Only one of 23 gentamicin-resistant cultures of Staphylococcus aureus
transferred its resistance in mixed culture in broth to the non-lysogenic
S. aureus strain 1030; the transfer-frequency was 10(-3)-10(-4). Transfer
between non-lysogenic clones of strain 1030 occurred at a similar frequency
in urine, and at a frequency of approximately 10(-1) in serum. The
resistance determinant for transfer between non-lysogenic clones was
usually linked to phage genome, as shown by the possession by resistant
recipients of immunity to typing phage 75, plaque-forming particles in
their culture filtrates and inducibility by mitomycin C. Stability of the
resistance on storage and transduction kinetics suggested that these genes
were chromosomal. Two resistant derivatives were isolated that had lost
some phage functions and were unable to transfer their resistance further.
The epidemiology of gentamicin resistance may in part be explicable by the
transient formation of an auto-transmissible element with subsequent
integration of the resistance genes into a variety of replicons (i.e.,
transposition).
