Based on your knowledge of beta-lactam drugs, which of the following antibiotics likely has the broadest spectrum?

• A. Cephalexin, a first generation cephalosporin.
• B. Meropenem.
• C. Oxacillin.
• D. Aztreonam.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the classification of beta-lactam antibiotics. Beta-lactams include penicillins, cephalosporins, carbapenems, and monobactams, each with different spectrums of activity against bacteria.
2. Step 2: Identify the spectrum of each antibiotic listed: Cephalexin is a first-generation cephalosporin, generally effective mainly against Gram-positive bacteria; Oxacillin is a penicillinase-resistant penicillin, mainly targeting Gram-positive bacteria; Aztreonam is a monobactam, primarily active against Gram-negative bacteria; Meropenem is a carbapenem, known for its broad spectrum covering many Gram-positive, Gram-negative, and anaerobic bacteria.
3. Step 3: Compare the spectrum breadth by considering the range of bacteria each antibiotic can inhibit. Carbapenems like Meropenem are designed to resist many beta-lactamases and have a wide range of activity, often broader than first-generation cephalosporins, penicillinase-resistant penicillins, and monobactams.
4. Step 4: Conclude that among the options, Meropenem likely has the broadest spectrum because it covers a wider variety of bacterial species, including many resistant strains, compared to the other listed antibiotics.
5. Step 5: Remember that the choice of antibiotic depends on the infection type and susceptibility patterns, but in terms of spectrum alone, carbapenems like Meropenem are generally considered the broadest among beta-lactams.