Final answer:
For an Ampicillin-sensitive Enterococcus faecalis resistant to gentamicin, a combination of ampicillin with streptomycin could be used for treatment as it could offer a synergistic effect and streptomycin is not mentioned to be resisted.
Step-by-step explanation:
The student has asked which combination of antibiotics could possibly be used for the treatment of an Ampicillin-sensitive Enterococcus faecalis with high-level resistance to the aminoglycoside gentamicin. Since the organism is sensitive to ampicillin but resistant to gentamicin, the use of gentamicin would be ineffective. Ampicillin is often used in combination with other antibiotics to enhance the bactericidal effect, and when treating infections like endocarditis, combinations are chosen for their synergistic effects.
A reasonable choice in this scenario would be ampicillin in combination with streptomycin, as streptomycin is another aminoglycoside that isn't specifically mentioned as having resistance. The other aminoglycosides listed (gentamicin, tobramycin, and amikacin) might be ineffective if the high-level aminoglycoside resistance observed with gentamicin extends to these related drugs.