From brenda@jupiter.esd.ornl.gov Mon Mar 20 10:47:32 1995

Dr. Gross,
I discussed some of the questions we had about pathway resistance with
Ed Smith at UT Hospital.
1.  If resistance was developed to an antibiotic working through 
a given pathway (i.e., inhibition of cell wall synthesis), would it
be more likely that the patient would develop resistance to other
drugs that used that same pathway? 
Yes, it is more likely, because it is more likely that a patient
will become resistant to an antibiotic that is structurally similar.
An example is the floroquinilones--it you are resistant to 1, you are
resistant to the whole class.  Also, for example if you are resistant to 
Aminoglycin (?) you will easily become resistant to Genamycin, but not
some likely to become resistant to Amakaysin, which is in the same family
but is structurally different.
Also, if a resistant bacteria acts by modifying a binding site (i.e.
protein 1), any antibiotics which act be binding to protein site 1
will not be useful.

2.  Is any one pathway the most common route for antibiotic
resistance?
He said that all are becoming more and more common.