Staphylococcal Infections and antibiotic resistance

Bacterial resistance to antibiotics is one of the top three health care concerns worldwide, with staphylococcal bacterial infections being one of the largest contributors to this growing problem. Additionally, complex non-healing wounds are often associated with the presence bacteria living as a protected community, otherwise known as biofilm. These chronic wounds often do not respond to commercially available agents. Eradicating biofilms from wounds is key for their healing. Otherwise, the limb is typically amputated, or the infection might aggressively spread, creating a high risk of death. Such infections, using conventional treatment modalities, now result in over 100,000 limb amputations [1] and ~90,000 people a year in the US alone [2]. Millions of people throughout the world suffer each year from wound infections. Those include diabetic foot ulcers, bedsores, traumatic injuries and also surgical wounds, creating a silent epidemic.  

 Many of the staph strains have developed resistance to the majority of antibiotics.  For example, methicillin-resistant S. aureus (MRSA) and vancomycin-intermediate resistant S. aureus (VISA) have developed, and infections with these organisms are on the rise.  Community-acquired MRSA (CA-MRSA) is causing a major public health alarm because it can be easily acquired through casual contact and must often be treated with antibiotics which are becoming less and less effective [3,4].

BACTERIA IN A BIOFILM ARE MORE RESISTANT TO ANTIBIOTICS      

Bacteria attach to a variety of surfaces, forming bacterial communities that exhibit properties, behaviors and survival strategies that far exceed their capabilities as individual bacteria. Importantly, compared to their free-floating (planktonic) counterparts, biofilm bacteria have an enhanced ability to survive and proliferate in infected hosts, and to secrete virulence factors (toxins) that enhance their survival while destroying the host. Bacteria in a biofilm have reduced susceptibility to host immune defense mechanisms and to antibiotics, and are up to x1000 more tolerant to common treatment modalities. It is estimated that biofilms contribute to at least 80% of all infections [6,7], yet commonly used antibiotics target planktonic bacteria and not biofilms! Thus novel antibiotics that target bacterial biofilms are urgently needed.

1.    http://www.infection-research.de/perspectives/detail/pressrelease/a_life_in_slime_biofilms_rule_the_world/

2.    Costerton, J.W., Stewart, P.S., Greenberg, E.P. Bacterial biofilms: a common cause of persistent infections. Science 1999; 284: 5418, 1318-22

3.    James GA, Swogger E, Wolcott R, Pulcini Ed, Secor P, Sestrich J, Costerton JW, Stewart PS. Biofilms in chronic wounds. Wound Repair Regen. 2008; 16:37-44

4.    Interagency Task Force on Problem of Bacterial Reistance to Antibiotics: http://www.cdc.gov/drugresistance/pdf/action-plan-2012.pdf

5.    http://www.cdc.gov/mrsa/statistics/MRSA-Surveillance-Summary.html

6.    CDC statistics:  www.mrsasurvivors.org/statistics

7.    http://www.statisticbrain.com/staph-infection-statistics/