Staphylococcus aureus infections

Staphylococcus aureus can cause a range of illnesses from minor skin infections, such as impetigo (may also be caused by Streptococcus pyogenes), boils (furuncles), pimples and abscesses, to life-threatening diseases such as necrotising pneumonia, endocarditis, toxic shock syndrome (TSS), and septicemia. Its incidence is from skin, soft tissue, respiratory, bone, joint, endovascular to wound infections. It is also one of the most common causes of nosocomial infections, especially post-surgical wound infections. Toxins from S. aureus, such as alpha toxin and Panton-Valentine Leukocidin (PVL) are major contributors to the virulence of S. aureus causing infections in the hospital as well as the community.

Staphylococcus aureus vaccine candidates

Vaccine candidates have been under development and used in clinical trials recently. They include the conjugate vaccine composed of S. aureus capsular polysaccharides type 5, 8 and 336 conjugated to a novel carrier protein, the mutant non-toxic recombinant Pseudomonas aeruginosa exotoxin A (rEPA); and toxoid vaccine candidates targeting PVL and alpha toxin.

Clostridium difficile infections

Clostridium difficile can cause diarrhoea, ranging from a mild disturbance to a very severe illness with ulceration and bleeding from the colon (colitis) and, at worst, perforation of the intestine leading to peritonitis. It can be fatal. Generally, it is only able to do this when the normal, healthy intestinal bacteria have been killed off by antibiotics. When not held back by the normal bacteria, it multiplies in the large intestine and produces two toxins (A and B) that damage the cells lining the intestine. These toxins are the cause of nosocomial diarrhoea and pseudomembranous colitis in antibiotic-associated disease. Most infections occur in hospitals (including community hospitals), nursing homes, etc, but can also occur at home.  The bacterium can form spores which enable it to survive in the environment outside the body and which protect it to some degree against cleaning detergents and chemical disinfectants.

Clostridium difficile vaccine

A toxoid-based vaccine using chemically detoxified toxins (Toxin A and B) has shown to be well-tolerated and able to generate an immune response to the two toxins with the ability to resolve recurrence of the disease.

Research

A programme of preclinical laboratory evaluation of vaccine components under development for safety, quality and potency has been carried out in NIBSC in support of the clinical trials conducted by the National Vaccine Evaluation Consortium, UK. This involves physico-chemical characterisation and assessment of residue toxicity and immunogenicity using both in vivo and in vitro models.