Back to the Future: Penicillin-Susceptible Staphylococcus Aureus

All health professionals know and fear antibiotic resistance. A penicillin resistance has been present in Staphylococcus aureus for years due to its widespread usage for bacterial infections. However, penicillin may be making its come back! New data suggests that penicillin may becoming out of a period of antibiotic resistance. A study published by the American Journal of Medicine examined penicillin resistance in methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia.

At the McGill University Health Centre in Montreal, Canada, all adult MSSA bacteremia from April 2010 to April 2015 were reviewed for susceptibility to penicillin, erythromycin, clindamycin, and trimethoprim-sulfamethoxazole.  Out of 324 samples of MSSA bacteremia, 90 were susceptible to penicillin. This means that more than one quarter of patients with MSSA bacterium could use parenteral penicillin for treatment. This returning treatment may possibly have pharmacokinetic advantages over other beta-lactam, such as amoxicillin. Such pharmacokinetic advantages could potentially lead to better outcomes in the treatment of bacterial infections.

While working at a community pharmacy, I often fill prescriptions for amoxicillin, but I have never seen a prescription for penicillin. This new discovery regarding penicillin resistance could lead to a change in prescribing patterns from physicians in the future. I think that this discovery is also valuable at this time because other antibiotic resistances are emerging in our population. Bringing back an old antibiotic would be very useful to combat bacterial infections that are not responding to current top antibiotics. Although it is great to see the renaissance of an old antibiotic, antibiotic resistance is a serious problem and will continue to be a serious problem unless pharmacists step in to provide effective patient counseling and form beneficial interprofessional relationships with prescribers.

Am J Med. Published online February 25, 2016.

Link to article

2 thoughts on “Back to the Future: Penicillin-Susceptible Staphylococcus Aureus”

  1. This article is very interesting to me. As an intern at a community pharmacy, I have seen a few prescriptions for penicillin, but they are fairly uncommon. As I think about this phenomenon of bacteria becoming susceptible to penicillin, it makes me think that antibiotic resistance is like a roller coaster. As bacteria become resistant to drug 1, drug 2 will treat it. But eventually, the bacteria will become resistant to drug 2 and susceptible again to drug 1. I think that this will continue along the years. Beta-lactams such as amoxicillin and penicillin are much less expensive than some of the current new antibiotics, so I am sure that many people who have a penicillin-susceptible bacterial infection will be treated successfully.

  2. Good stuff. Were it not for antibiotics, and the troubles we face in their effectiveness, I believe we may have not come to understand the ability of an organism to evolve as we do now. In this arms race against biology, we can also appreciate the resilience of microbes, and of researchers working around the clock to develop new therapies as lives are on the line.

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