My question in biochemistry this week is how bacterial infections cause so many deaths each year. I had this question because I hear all the time that patients die of “infection,” but I have no idea what this means or how such a generic term can be used to cover so many deaths.

To clarify, infection causes millions of deaths worldwide, and is often seen even in patients that have been hospitalized1. In 2011, about 721,800 deaths resulted from infections in U.S. hospitals alone. It is estimated that this number can decrease by nearly seventy percent if proper protocols are followed and patients adhere to approved guidelines2.  In particular, what causes death appears not to be the infection in and of itself, but rather the body’s overwhelming response to the pathogens. This phenomenon is known as sepsis, or septic shock3. The body’s immune response causes an attack on its own organs and tissues. This can cause organ failure in severe circumstances, which can lead to death if not treated in a timely fashion4.

As sepsis causes so many deaths each year, its treatment options are widely known. Typically, patients are treated with antibiotics as soon as symptoms show. Antibiotics work by targeting pathways and compounds used by infectious agents, but not by humans. For example, penicillin acts by inhibiting crosslink formation in bacterial cell walls, thereby only affecting bacteria5. Azithromycin prevents translation by 50S ribosomes, which are possessed by prokaryotic cells6.

Most infections occur as a result of improperly following sterile medical protocol, both by medical staff and patients. Typically, this happens post-surgery. As a result, most hospitals must publish data on cases of infection and review it internally at conferences known as “morbidity and mortality conferences” that occur periodically to prevent malpractice7.

  • Raj K.


  1. Deutschman CS, Tracey KJ. Sepsis: current dogma and new perspectives. Immunity. 2014;40(4):463-75.
  2. HAI Data and Statistics, Center for Disease Control, 2011
  3. “The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)”. February 23, 2016.
  4. Dellinger RP, Levy MM, Rhodes A, et al. Surviving sepsis campaign: international guidelines for management of severe sepsis and septic shock: 2012. Crit Care Med. 2013;41(2):580-637.
  5. Shi Q, Meroueh SO, Fisher JF, Mobashery S. A computational evaluation of the mechanism of penicillin-binding protein-catalyzed cross-linking of the bacterial cell wall. J Am Chem Soc. 2011;133(14):5274-83.
  6. Bakheit AH, Al-hadiya BM, Abd-elgalil AA. Azithromycin. Profiles Drug Subst Excip Relat Methodol. 2014;39:1-40.
  7. Campbell WB. Surgical morbidity and mortality meetings. Ann R Coll Surg Engl. 1988;70(6):363-5.