INCREASE IN ANTIBIOTIC RESISTANCE (NNIS 1999)

Question

Resistance
60%
50%
40%
30%
20%
10%
0% Cana lo
1981 1985 1989 1993
1997
•- MRSA
•- VRE
+ FQRP
2001
Figure 4. The graph above shows the % of bacterial resistance
to several different antibiotics.
#10. A bacterial population was exposed to an antibiotic. Most of
the bacteria died, but a few survived and reproduced. What
would you expect to happen if the bacterial population was
exposed to the same antibiotic again?
(2 points)
A. All of the bacteria will die because the antibiotics will
know what to kill this time.
B. Most of the bacteria will die again but a few will survive
because the antibiotic can't reach all of them.
O
C. The bacteria will infect the antibiotic.
D. Most of the bacteria will survive because the surviving
bacteria from the first round passed on their resistant
traits.

Answer 1

The correct answer is:

D. Most of the bacteria will survive because the surviving bacteria from the first round passed on their resistant traits.

When a bacterial population is exposed to an antibiotic, those bacteria that have or develop resistance to the antibiotic may survive. When they reproduce, they pass on their resistant traits to the next generation. As a result, if the bacterial population is exposed to the same antibiotic again, it is likely that a larger proportion of the bacteria will be resistant and survive the treatment.