Among beta-lactams, which class is described as having the broadest spectrum and includes agents like imipenem and meropenem?

• A. Carbapenems
• B. Semi-Synthetic Penicillins
• C. First-Generation Cephalosporins
• D. Fifth-Generation Cephalosporins

Answer: (A)

Carbapenems have the broadest spectrum among beta-lactams. They cover many Gram-positive cocci, a wide range of Gram-negative rods, and anaerobes, making them especially useful for severe, polymicrobial infections and for organisms resistant to other beta-lactams. Imipenem and meropenem are classic examples, and their structure provides strong stability against many beta-lactamases. Imipenem is often given with cilastatin to prevent renal inactivation, whereas meropenem does not require that combination. Other options listed have narrower spectra: semi-synthetic penicillins target mostly certain Gram-negatives plus Gram-positives; first-generation cephalosporins are mainly effective against Gram-positive bacteria with limited Gram-negative activity; fifth-generation cephalosporins broaden Gram-positive coverage (including MRSA) but do not match the wide range of carbapenems.