Question

A 44-year old male with kidney disease is admitted to the hospital due to the flesh-eating disease (aka necrotizing fasciitis). The patient is thought to have developed this disease from a scrape while doing yard work. This particular disease can be caused by different bacteria including but not limited to Group A Streptococcus pyogenes, Staphylococcus aureus and Vibrio vulnificus, which is found in sea water! Immediate treatment with onset of signs/symptoms is crucial and usually requires IV antibiotic treatment and surgical removal of necrotic tissue. While this disease is NOT the result of bacteria literally eating flesh (it’s due to toxins they produce), it CAN result in loss of limbs and/or life.

S. pyogenes is NOT a strict/obligate anaerobe. What two metabolic pathways can this bacterium use to produce ATP? Why? Hint: Think about the bacteria growing on the skin (what metabolic pathway would it use?) and then think about the bacteria growing in deeper/necrotic tissue (what metabolic pathway would it use?).

Metabolic pathway on skin:

Metabolic pathway in deep tissue:

Answer 1

Streptococcus pyogenes is a facultative anaerobe or in other words an aerotolerant anaerobe .

That is it is primarily an anaerobe but can also grow in aerobic conditions.

Metabolic pathway on the skin: due to the presence of oxygen and availability of glucose from the surrounding blood vessels , it chooses the EMP pathway or Embden Meyerhof Parnas pathway for production of ATP.

Metabolic pathway in deep tissue: in the deeper tissue due to absence of aerobic conditions and also due to a scarce availability of glucose , the bacteria shifts to Malate degradation pathway , to produce ATP and to survive in the highly acidic zone .