The vaccine works
Staphylococcus aureus (S.aureus) causes more than 30,000 deaths from hospital-acquired infections in the United States annually and costs the healthcare system $10 billion. It is associated with a wide range of acute and chronic diseases, such as bacteremia, sepsis, skin and soft tissue infections, infectious endocarditis and osteomyelitis (bone infection), and is accompanied by high mortality (for example, 20-30% of patients die with bacteremia).
American researchers from the University of Maryland, led by (unfortunately, the late) Professor Mark E. Shirtliff, have developed and tested an experimental anti-staphlococcal vaccine on mouse and rabbit models of S. aureus infection. More than 80% of the immunized mice survived, and two-thirds of them were completely cured, compared with less than 10% of the control animals. On the 21st day after infection, the surviving animals – both immunized and control animals – showed no signs of poor health, such as ruffled fur or other appearance abnormalities, and they all regained the weight they had before infection.
In experiments on rabbits, researchers injected a pathogen into the bone marrow of the tibia to create a model of osteomyelitis. Twenty-four days after infection, almost two-thirds of the immunized rabbits got rid of the infection; none of the individuals from the control group had such a result. While control rabbits had perforated bone lesions, vaccinated rabbits had less or no damage at all. (Rabbits, as a rule, do not succumb to S.aureus infection.)
Effective vaccination can be of great therapeutic value for patients after surgery, especially orthopedic and cardiovascular operations, when medical devices are implanted, as well as in cases of traumatic injuries. Infections at the surgical site account for 20% of all hospital-acquired infections, and S.aureus is the main causative agent.
The variety of diseases caused by S.aureus is due to the differential expression of more than 70 virulence factors. Virulence factors initiate colonization and growth, mediate host damage and interfere with the immune response.
Biofilm formation is a powerful virulence factor. S.aureus is difficult to destroy largely because it forms biofilms so easily. They are communities of bacteria that stick strongly to surfaces, like plaque. Biofilms are particularly resistant to the host's immune response and to antibiotics, because they do not allow drugs inside, and the bacteria inside have a low metabolism, further reducing the possibility of penetration of antibiotics and antibodies into bacterial cells. Biofilms are often formed on joint implants and cardiac devices. They can form wherever there is a surface, moisture and a source of nutrients.
The vaccine developed by the researchers recognizes five different S. aureus proteins. Four of these proteins are specific to S. aureus biofilms, and one is specific to S. aureus in the free state.
Article by J. M. Harro et al. Clearance of Staphylococcus aureusfrom In Vivo Models of Chronic Infection by Immunization Requires Both Planktonic and Biofilm Antigens is published in the journal Infection and Immunity.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of the American Society for Microbiology: New vaccine protects from widespread, costly infection, mice study shows.