Experimental Vaccine Defeats S Aureus Infections

Dentistry Today


Janette Harro, PhD, has developed an experimental vaccine that protects up to 80% of mice against Staphylococcus aureus, which accounts for a third of the deadly healthcare-acquired infections (HIAs) that often emerge after people undergo surgical procedures. 

A research assistant professor with the University of Maryland School of Dentistry (UMSOD) Department of Microbial Pathogenesis, Harro notes that the vaccine also has proven effective in 66% of rabbits infected with S aureus, the most deadly Staph bacterium. 

Though tested only in animals so far, the vaccine has shown the potential to drastically reduce the number of patients who succumb to S aureus infections post-surgery, a time when their immune systems already are compromised, Harro and her colleagues believe. 

“This vaccine could prove hugely beneficial, especially for orthopedic and cardiovascular patients, for example, where medical structures or devices are implanted,” said Harro. “S aureus is difficult to eradicate because it so readily forms biofilms at the surgical site.” 

“Preliminary results are very promising, and we are hopeful that this vaccine will prove protective in humans as well,” said Mark A. Reynolds, DDS, PhD, dean and professor at UMSOD. “Dr. Harro and colleagues’ innovative research offers the potential of significantly reducing the risk of life-threatening S aureus infections following surgery.”

In theory, Harro said, if patients undergoing elective surgeries can be immunized prior to surgery with a vaccine that protects against a deadly S aureus infection, both fatalities and healthcare costs could be markedly reduced. 

“Biofilms unfortunately are very hard to treat,” said Harro. “Antibiotics don’t work well, and the immune system can’t clear it effectively on its own.”

HIAs account for about 1.7 million infections and 99,000 associated deaths each year, reports the Centers for Disease Control and Prevention, mostly due to their virulence and resistance to traditional antibiotics. Also, S aureuscosts the US healthcare system $10 billion each year.  

Most vulnerable are young children, the elderly, and patients with compromised immune systems. Longer hospital stays put patients at greater risk, along with poor hygiene, antibiotic resistance, and the use of catheters. 

A surgical site can be contaminated by contact from a healthcare provider, with equipment, or from germs already on the body or in the air. About 2% to 5% of patients undergoing surgery succumb to HIAs. 

The next steps for the experimental vaccine involve testing in a wider range of animal models and analyzing its effectiveness across various strains of the bacterium as well as with multiple conditions such as skin and soft tissue infections, bone and joint infections, bloodstream infections, pneumonia, and septic shock.

The study, “Clearance of Staphylococcus Aureus from In Vivo Models of Chronic Infection by Immunization Requires Both Planktonic and Biofilm Antigens,” was published by Infection and Immunity.

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