Most bacteria coexist with humans without harm. However, some bacterial species cause severe infection with potentially disabling or life-threatening consequences. Disease-causing bacteria are termed pathogens. The bacteria Neisseria meningitidis, Mycobacterium leprae and Clostridium perfringens cause three notoriously feared infections--meningitis, leprosy and gas gangrene, respectively. Each of these infections is curable, in most cases, with early diagnosis and treatment.
Neisseria meningitidis
Neisseria meningitidis, better known as meningococcus, can be a virulent human pathogen. Unlike most other pathogens that can exist outside the human body, meningococcus lives only in the human nose and throat. In a 2009 article published in the journal, "Vaccine," Drs. Dominique Caugantab and Martin Maiden report an estimated 10 to 35 percent of young adults are carriers of meningococcus at any given point in time. In a small proportion of those who carry meningococcus, the bacteria migrate from the nose and throat to the bloodstream and spread throughout the body. Caugantab and Maiden report approximately 50 percent of those with meningococcal blood infections develop meningitis. The Centers for Disease Control and Prevention reports at least one out of every 10 people who develop meningococcal disease dies of the illness. Among survivors, up to 19 percent suffer permanent disabilities such as mental retardation, deafness or limb amputations.
Mycobacterium leprae
The bacterium Mycobacterium leprae can cause Hansen's disease, commonly known as leprosy. Mycobacterium leprae grows exceptionally slowly. According to the reference text, "Principles and Practice of Infectious Diseases," the average incubation period between contracting M. leprae and the onset of the disease is five to seven years. M. leprae can attacks the skin, upper respiratory tract and the nerves outside the brain and spinal cord. Thickened skin, lumps, and inflamed areas of skin known as plaques typically develop. Loss of sensation due to nerve infection in the extremities can be particularly debilitating. The inability to sense temperature or pain leads to frequent accidental self-injury. The National Hansen's Disease Program points out that early antibiotic treatment effectively prevents damaging nerve involvement.
Clostridium perfringens
Clostridium perfringens is the primary cause of clostridial myonecrosis, more commonly known as gas gangrene--a rapidly progressive, destructive form of wound infection. Dr. Kenneth Todar, author of "Todar's Online Textbook of Bacteriology," reports that gas gangrene typically occurs when C. perfringens contaminates a traumatic or surgical wound. Enzymes produced by the bacteria promote invasion into the surrounding tissues. Inordinately severe pain at the site of the wound and gas within the tissues are hallmark characteristics of gas gangrene. As noted in, "Principles and Practice of Infectious Diseases," surgical removal of dead and infected tissue and aggressive treatment with antibiotics are the mainstays of treatment for gas gangrene.
References
- "Vaccine"; Meningococcal Carriage and Disease--Population Biology and Evolution; Dominique A. Caugantab, Martin C.J. Maiden; June 2009
- Centers for Disease Control and Prevention: Meningitis, Clinical Information for Healthcare Professionals
- Centers for Disease Control and Prevention: Hansen's Disease (Leprosy)
- U.S. Health Resources and Services Administration: National Hansen's Disease (Leprosy) Program
- Todar's Online Textbook of Bacteriology: Pathogenic Clostridia, including Botulism and Tetanus
