Mycoplasma pneumoniae is innately resistant to all beta-lactam antibiotics. The structural basis of this resistance is:

• A Absence of a peptidoglycan cell wall ✓
• B Altered penicillin-binding proteins with reduced affinity
• C Production of extended-spectrum beta-lactamases
• D An impermeable polysaccharide capsule

Explanation

Beta-lactams act by inhibiting transpeptidation of the peptidoglycan layer of the bacterial cell wall. Mycoplasmas are the smallest free-living bacteria and completely lack a cell wall, being bounded only by a sterol-containing plasma membrane, so they have no target for penicillins. Beta-lactamase production and altered PBP mechanisms apply to wall-containing bacteria such as enterobacteria and pneumococcus, not to mycoplasmas.

Reference: Jawetz, Melnick and Adelberg's Medical Microbiology, 28th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.