Final answer:
Oxacillin and nafcillin may be used IV in the treatment of bacterial infections caused by Staphylococcus spp. and Streptococcus spp., but they may not be effective against MRSA infections.
Step-by-step explanation:
Oxacillin and nafcillin are often used intravenously (IV) in the treatment of certain bacterial infections caused by Staphylococcus spp. and Streptococcus spp. These antibiotics belong to the penicillin class and are effective against gram-positive bacteria. However, it's important to note that these drugs may not be effective against methicillin-resistant Staphylococcus aureus (MRSA) infections, as MRSA is resistant to many beta-lactam antibiotics.