Which feature contributes to the resistance of Gram-negative bacteria?

Which feature contributes to the resistance of Gram-negative bacteria?

• A. Outer membrane containing lipopolysaccharide
• B. Peptidoglycan layer is thicker
• C. No outer membrane
• D. Endospore formation common

Answer: (A)

A Gram-negative cell’s outer membrane with lipopolysaccharide forms a protective barrier that makes many antimicrobial agents less able to reach their targets. This outer membrane restricts entry of drugs through porin channels, and the LPS layer together with the periplasmic space hosts enzymes like beta-lactamases that can inactivate antibiotics before they can act. This permeability barrier, plus specialized transport and efflux mechanisms, underlies much of the intrinsic resistance seen in Gram-negative bacteria. In contrast, Gram-positive bacteria lack this outer membrane and instead have a thick peptidoglycan layer exposed to the environment, while endospore formation is a resistance strategy more typical of certain Gram-positive genera. Thus, the outer membrane containing lipopolysaccharide is the feature that contributes to resistance.

A Gram-negative cell’s outer membrane with lipopolysaccharide forms a protective barrier that makes many antimicrobial agents less able to reach their targets. This outer membrane restricts entry of drugs through porin channels, and the LPS layer together with the periplasmic space hosts enzymes like beta-lactamases that can inactivate antibiotics before they can act. This permeability barrier, plus specialized transport and efflux mechanisms, underlies much of the intrinsic resistance seen in Gram-negative bacteria. In contrast, Gram-positive bacteria lack this outer membrane and instead have a thick peptidoglycan layer exposed to the environment, while endospore formation is a resistance strategy more typical of certain Gram-positive genera. Thus, the outer membrane containing lipopolysaccharide is the feature that contributes to resistance.