This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Microbiology (Sterilization and Bacterial Genetics), Subject name: Microbiology
Following are true of transferable drug resistance except : 
Select and explain. 
A. Multiple drug resistance simultaneously, B. Virulence of bacteria same, C. Prevented by drug combinations, D. Very high degree of resistance
C: Prevented by drug combinations
Answer: C: Prevented by drug combinations 
Explanation: Drug Resistance 1. Transferable drug resistance cannot be prevented by use of drug combinations. Drug combinations are used to get synergistic effect of antibiotics on pathogens in serious diseases. 2. Antimicrobial resistance can be of two types:-* Intrinsic Resistance: It is the innate ability of a bacterium to resist a class of antibiotics* Acquired Resistance: It is the emergence of resistance in bacteria, by acquiring the drug resistant genes either by - (i) Mutational or by (ii) Transferable drug resistance 3. Transferable drug resistance: * Multiple drug resistance at the same time* High degree resistance* Cannot be overcome by drug combinations* Virulence not decreased* Resistance is transferable to other organisms- Spread by: horizontal spread (conjugation, or rarely by transduction/transformation) 4. Transfer of plasmids during conjugation is responsible for the spread of multiple drug resistance among bacteria. -The plasmid responsible for drug resistance consists of two components, namely, F and a resistance determinant (r) for each of the several drugs. -Transferable drug resistance occurs widely among pathogenic as well as commensal bacteria of humans and animals. Plasmid is also responsible for production of colicins, the antibiotic-like substances lethal to other Gram-negative bacteria. -The plasmid that encodes for production of colicins is known as col factor and is also transferred by conjugation.