Final answer:
The correct answer is option a. Bacteria become resistant to penicillin and similar drugs primarily by producing beta-lactamase enzymes like penicillinase, which break down the antibiotic and render it ineffective.
Step-by-step explanation:
The mechanism that renders bacteria resistant to penicillin and similar drugs is producing beta-lactamase enzymes. These enzymes, most notably penicillinase, function by breaking down the antibiotics, particularly through the cleavage of the amide linkage in the lactam ring.
This enzymatic action inactivates the drug and prevents it from being effective against the bacterial cell wall. Beta-lactam antibiotics, which include penicillins, cephalosporins, carbapenems, and monobactams, target penicillin-binding proteins (PBPs) that are crucial for bacterial cell wall synthesis.
When bacteria produce beta-lactamase, the structural integrity of the antibiotic is compromised, leading to drug resistance. Other resistance mechanisms involve mutation of targets on the bacterial cell's surface, producing a bypass protein that negates the antibiotic's effect, or preventing the antibiotic's entry into the cell. However, the correct answer in this context is option (a) producing beta-lactamase enzymes.