A PEDIATRIC PATHOGEN: Staphylococci remain one of the most important pathogenic agents leading to
community-acquired infection in children. Over the last decades, there has been an evolution in the localizations of these
infections: dramatic pleuropulmonary
staphylococcal infection in newborns has almost entirely disappeared in developed countries. Conversely, skin
infections and
soft tissue infections as well as bone and joint localizations are frequent. The severity of these bone and joint
infections has however declined allowing less aggressive therapeutic regimens. One of the current problems is the risk of emergence of
meticillin-resistant strains causing
community-acquired infections. Such
infections have been very rare in France but careful monitoring is nevertheless necessary.
NOSOCOMIAL INFECTION: Staphylococci are however the leading cause of
nosocomial infections in children, particularly in intensive care units. All localizations are concerned, especially
catheter-related
septicemia and
pneumonia. There has been an increasing trend for Staphylococcus aureus and
coagulase-negative staphylococci
infections. Most of the strains isolated are
meticillin-resistant. TOXINS: Staphylococcus aureus secretes toxins leading to specific diseases:
enterotoxins cause
food-poisoning and exofoliatines cause generalized exfoliation and bullous
impetigo. Staphylococcal scarlatina is related to the
shock provoked by staphylococcal toxins:
TSST-1 and entrotoxins. Staphylococcal
toxic shock syndrome is a relatively new entity more frequently observed in adults but which was initially described in children. The disease may develop during any
staphylococcal infection, particularly after
superinfection of a skin
burn or
varicella. MECHANISM OF ACTION OF TOXINS: Staphylococcal toxins act like
superantigens, capable of provoking polyclonal activation of a large number of T cells. This leads to the release of an important quantity of
cytokines that intervene in the pathogenesis of toxic diseases. This polyclonal activation has been observed in other pediatric diseases of unknown origin but in which the involvement of staphylococcal toxins can be suspected. There is solid evidence in favor of staphylococcal toxins in
Kawasaki syndrome. Likewise, these toxins could be implicated in
sudden death syndrome in infants and in acute exacerbations of atopic exzema.