A patient with walking pneumonia not responding to penicillin. This is due to

A patient with walking pneumonia not responding to penicillin. This is due to

• A. Organism developed penicillinase
• B. Organism has no cell wall
• C. Organism is intracellular
• D. Organism is resistant to all antibiotics

Answer: (B)

Penicillin targets cell wall synthesis, so organisms that lack a cell wall are inherently unaffected by it. Walking pneumonia is caused by Mycoplasma pneumoniae, which has no peptidoglycan cell wall, so there’s nothing for penicillin to disrupt. That intrinsic absence of a cell wall is why penicillin doesn’t work here. Infections like this are treated with antibiotics that don’t rely on targeting a cell wall, such as macrolides or doxycycline. Penicillinase production would explain resistance in bacteria that still have a cell wall, but it isn’t the reason Mycoplasma pneumoniae resists penicillin. The organism isn’t intracellular, and it isn’t resistant to all antibiotics—macrolides and tetracyclines can be effective.

Penicillin targets cell wall synthesis, so organisms that lack a cell wall are inherently unaffected by it. Walking pneumonia is caused by Mycoplasma pneumoniae, which has no peptidoglycan cell wall, so there’s nothing for penicillin to disrupt. That intrinsic absence of a cell wall is why penicillin doesn’t work here. Infections like this are treated with antibiotics that don’t rely on targeting a cell wall, such as macrolides or doxycycline.

Penicillinase production would explain resistance in bacteria that still have a cell wall, but it isn’t the reason Mycoplasma pneumoniae resists penicillin. The organism isn’t intracellular, and it isn’t resistant to all antibiotics—macrolides and tetracyclines can be effective.