Many types of bacteria can inhabit or infect the human body. Those that live harmlessly in or on the body are colonizers. Bacteria that cause disease are pathogens. Certain bacteria may be colonizers, but can cause disease under specific conditions. These bacteria are opportunistic pathogens. Staphylococcus epidermidis and Gardnerella vaginalis are two examples of colonizers that may become opportunistic pathogens. Clostridium difficile is an illustrative example of a pathogenic bacterium.
Staphylococcus Epidermidis
Staphylococcus epidermidis normally colonizes the skin and nose. These bacteria, however, are common opportunistic pathogens. Typically, S. epidermidis causes infection and disease when illness or injury occurs. In an article published in "Emerging Infectious Diseases," Dr. Maria Sjölund and colleagues reported S. epidermidis is a significant cause of hospital-acquired infections. S. epidermidis may gain entry to the body through intravenous catheters, urinary catheters and surgical wounds. People with a weakened immune system are particularly vulnerable. Intravenous drug use is also a risk factor for S. epidermidis infections. The medical reference text, "Principles and Practice of Infectious Diseases," reports S. epidermidis may cause endocarditis, peritonitis, urinary tract infection, and bone and bloodstream infections.
Gardnerella Vaginalis
The bacterium Gardnerella vaginalis and other types of bacteria are normal colonizers of the vagina. Disturbances in the bacterial balance of the vagina cause the condition known as bacterial vaginosis. In an article published in "American Family Physician," Dr. Barbara Majeroni explains that bacterial vaginosis represents an overgrowth of some colonizers of the vagina, including Gardnerella vaginalis. The overgrowth is accompanied by loss of the Lactobacillus species that normally inhabit the vagina. Possible symptoms of bacterial vaginosis include vaginal itching or burning, pain and malodorous discharge. The U.S. Centers for Disease Control and Prevention advises women that antibiotic treatment for bacterial vaginosis is important because the infection can lead to pelvic inflammatory disease. Additionally, bacterial vaginosis increases a woman's susceptibility to sexually transmitted diseases including HIV, gonorrhea, herpes and chlamydia.
Clostridium Difficile
Clostridium difficile is a pathogenic bacteria that causes diarrhea and colitis, an inflammation of the colon. In an article published in "American Family Physician," Dr. Michael Schroeder reports that approximately 3 million cases of Clostridium difficile diarrhea and colitis occur annually in the United States. C. difficile infections are primarily contracted in a hospital or long-term care facility setting. People with underlying systemic diseases, preexisting bowel disease, a weakened immune system, and older adults are most likely to develop C. difficile-associated disease. Recent antibiotic treatment increases the risk for C. difficile infections. Symptoms include fever, nausea, abdominal pain and watery diarrhea. In a patient information article published in "The Journal of the American Medical Association," Dr. Janet Torpy explains that severe cases of C. difficile can cause extensive damage to the wall of the large intestine. This is termed pseudomembranous colitis. A serious complication of pseudomembranous colitis is intestinal perforation--the development of a hole in the intestine. This complication is potentially life-threatening.
References
- Emerging Infectious Diseases; Persistence of Resistant Staphylococcus epidermidis after Single Course of Clarithromycin; Maria Sjölund, et al.; September 2005
- American Family Physician; Bacterial Vaginosis--An Update; Barbara A. Majeroni, M.D.; March 1998
- U.S. Centers for Disease Control and Prevention: Bacterial Vaginosis Fact Sheet
- The Journal of the American Medical Association; Clostridium difficile Colitis; Janet M. Torpy, et al.; March 2009
- U.S. Centers for Disease Control and Prevention: General Information About Clostridium Difficile Infections
