This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
All of the following factors increase the risk of aminoglycoside renal toxicity, except: 
Select and explain. 
A. Elderly person, B. Hypokalemia, C. Simultaneous use with penicillin, D. Aminoglycoside administration in recent past
C: Simultaneous use with penicillin
Answer: C: Simultaneous use with penicillin 
Explanation: Administration of penicillin along with aminoglycoside does not increase the risk of aminoglycoside renal toxicity. Aminoglycosides are highly effective against gram negative bacteria whereas penicillins are effective against gram positive bacteria. Penicillins also increase the bactericidal activity of aminoglycosides. Combination of penicillins/cephalosporins and aminoglycosides is the treatment of choice for pseudomonas infections. Ref: The Spinal Cord Injured Patient By Bok Y. Lee, 2nd Edition, Page 82