Impetigo is a bacterial infection caused by Streptococcus and/or Staphylococcus organisms. Both staphylococcus and streptococcus are part of the normal flora found on human skin, but given the opportunity they can become pathogenic. Streptococcus is a spherical bacterium that is arranged into chains. It is Gram positive and catalase negative. Group A Streptococcus (GAS), such as Streptococcus pyogenes, are responsible for most cases of streptococcal infections. The letter A is part of a classification system that separates streptococcal organisms according to the composition of the cell wall. Other illnesses associated with GAS are "strep throat", necrotizing fasciitis, and streptococcal toxic shock syndrome (4,9).
Staphylococcus is arranged into clusters of spherical bacteria. They are Gram positive and catalase positive. Staphylococcus bacteria are classified into two major groups, aureus and non-aureus. Staphylococcus aureus is another organism that causes impetigo. It is distinguished from other species by a positive result in a coagulase test. Staphylococcus aureus is also associated with soft tissue infection as well as toxic shock syndrome and has been found to be the causative agent in pneumonia, boils, arthritis, meningitis and osteomyelitis. The pathogenic abilities of Staphylococcus are most commonly associated with the toxins it produces in the stationary phase of the bacterial growth curve (2).
Impetigo involves an infection of the superficial, top layers, of the skin. It is characterized by the development of red blisters that start to rupture and ooze fluid. A yellowish or honey colored crust then develops. It usually effects the face, hands, arms, and legs but may spread to other areas by scratching. Occasionally a person will become ill experiencing symptoms like headache, muscle aches, fever, nausea and fatigue. In rare cases the infection may spread and cause post-streptococcal glomerulonephritis (kidney failure). A diagnosis will primarily be based on the appearance of the lesions on the skin but a culture can be taken from active lesions to test for the presence of streptococcus or staphylococcus (6,7).
The occurrence of impetigo is worldwide. Children are most at risk for developing impetigo, particularly if they are exposed to poor hygienic conditions. Most outbreaks occur in areas like schools and day care centers. They may acquire impetigo through direct contact with an infected person or the bacteria will enter through a break in the skin caused by insect bites, animal bites or other trauma to the skin. Children who often have cuts and scrapes on their body are more vulnerable to impetigo. Household items like toys or cups probably do not play a major role in the transmission of the disease. Sometimes it develops out of the blue with no apparent source of infection. The incubation period from date of exposure to the first signs is...