Which cells are medically important due to association with chronic infections that do not respond to antibiotic treatment?

• A. Persister cells
• B. Obligate anaerobes
• C. Facultative anaerobes
• D. Aerotolerant anaerobes

Answer: (A)

Persister cells are a small subset of bacteria that can switch into a dormant state, becoming tolerant to antibiotics that kill actively growing cells. This tolerance isn’t due to genetic resistance; the cells are simply metabolically inactive, so antibiotics targeting processes like cell wall synthesis or DNA replication have little effect while they’re dormant. In chronic infections, persisters can survive a full course of antibiotics and later wake up to repopulate, causing relapse. They’re also common in biofilms, where slow growth and protective microenvironments further promote persistence. That combination—surviving antibiotic treatment and driving relapse in chronic infections—is what makes persister cells medically important. The other options refer to oxygen needs or tolerances and don’t inherently explain antibiotic tolerance or persistence in chronic infections.