Staphylococcal bacteria are significant human pathogens, causing a broad array of infections, which range in severity from mild to potentially life-threatening. Different forms of Staph exhibit a propensity for causing specific types of infections. Colonization of human skin and the common presence of Staph in the environment provide abundant reservoirs for infection when the protective barriers of the body are breached. Growing antibiotic resistance found among certain strains of Staph poses a serious public health threat.
Staphylococcus Aureus
Staphylococcus aureus, or Staph aureus, remains a leading cause of human infections. Many healthy people harbor Staph aureus on the skin or in the nasal cavity. Carriers of Staph aureus may become infected if the bacteria gain an opportunity to enter the body. Personal contacts of carriers can be similarly infected. Additionally, Staph aureus survives well on inanimate surfaces and resists killing by many types of disinfectants, further extending the opportunities for infection.
The medical reference text "Principles and Practice of Infectious Diseases" notes a variety of skin infections frequently caused by Staph aureus, including folliculitis, an infection of the hair follicles; boils, abscesses of the hair follicles; styes, abscesses of the eyelids; hydradenitis supprativa, an infection of the sweat glands; impetigo, an infection of the uppermost layers of the skin; cellulitis, an infection of the deep layers of the skin; mastitis, an infection of the breast; and wound infections.
Invasive infections that may be caused by Staph aureus include pneumonia, meningitis, urinary tract infections, endocarditis, an infection of the heart, and osteomyelitis, an infection of the bone. Staph aureus also remains a common cause of food poisoning. Certain strains of Staph aureus produce toxic proteins that can provoke toxic shock syndrome, a potentially life-threatening systemic illness.
MRSA
Methicillin-resistant Staphylococcus aureus, or MRSA, is a variant strain of Staphylococcus aureus that resists killing by an array of antibiotics, including methicillin, penicillin, amoxicillin, oxacillin and others. The Centers for Disease Control and Prevention reports that MRSA accounts for the majority of serious staphylococcal infections. In an October 2007 article published in "The Journal of the American Medical Association," Dr. R. Monina Klevens and colleagues report that the most common forms of MRSA infections include bacteremia, a bloodstream infection, pneumonia and cellulitis.
Staphylococcus Epidermidis
Staphylococcus epidermidis, or Staph epi, is a normal inhabitant of human skin. Although harmless when living on top of the skin, Staph epi can cause serious infections when presented with an opportunity to enter the body. Sites commonly infected by Staph epi include the urinary tract, especially related to bladder catheterization; surgical or traumatic wounds; bones exposed through surgery or trauma; intravenous catheters or central lines; replacement heart valves; joint replacement prostheses; and breast implants.
References
- "Principles and Practice of Infectious Diseases, Sixth Edition"; Gerald L. Mandell, M.D., et al., Editors; 2004
- Centers for Disease Control and Prevention: Healthcare-associated Methicillin Resistant Staphylococcus aureus (HA-MRSA)
- "The Journal of the American Medical Association"; Invasive Methicillin-Resistant Staphylococcus aureus Infections in the United States; R. Monina Klevens, D.D.S., M.P.H., et al.; October 2007
- Todar's Online Textbook of Bacteriology: Staphylococcus aureus and Staphylococcal Disease
- Microbiology and Immunology Online, University of South Carolina School of Medicine: Streptococcus Pneumoniae and Staphylococci
