Methicillin is a type of antibiotic that belongs to the penicillin family. It was developed to treat infections caused by certain bacteria, particularly those that are resistant to other penicillins. Methicillin works by inhibiting the growth of bacteria, making it effective against infections like Staphylococcus aureus. However, the use of methicillin has declined due to the emergence of methicillin-resistant Staphylococcus aureus (MRSA), a strain of bacteria that has developed resistance to this antibiotic. As a result, healthcare providers often rely on alternative treatments to manage infections caused by MRSA and other resistant bacteria.