Transcript Tetanus
Tetanus “LOCK JAW” Clostridia: general characteristics Genus Clostridium contains a large number of gram-positive, spore-forming species, several of which are able to produce disease in humans. Most species are obligate anaerobes, some will grow under microaerophilic conditions. Natural habitat: soil and the intestinal tracts of animals and humans. Very active metabolisms, ferment a variety of sugars, very short generation times. C. tetani: key characteristics Large, spore-forming, motile, obligate anaerobic bacillus (see below). Ferments: proteins or amino acids. Produces: acetic acid, fatty acids, NH3, CO2, H2, and a strong exotoxin. Tetanospasmin, a powerful neurotoxin. Tetanus etiology Tetanus does not follow typical infectious disease patterns where microbes are passed from host to host. Some situations are conducive to tetanus, however. Soils or materials in contact with animal wastes are usually heavily contaminated with C. tetani and offer excellent sources of infection. Soil-contaminated wounds are the most frequent source of infection. Before the development of an effective vaccine, tetanus often resulted from wounds received in battle. Access of tetanus spores to open wounds does not necessarily result in disease: C. tetani can often be cultured from wounds of patients without tetanus, because in clean wounds with good blood supply and high oxygen tension, germination rarely occurs. In necrotic and infected wounds, anaerobic conditions will permit germination. Contaminated puncture wounds can be particularly dangerous, especially when a foreign body is present. Spores may occasionally lay dormant in a healed wound for months or years; trauma to the area may then cause germination and disease. Tetanus symptoms & signs Tetanus is an acute, potentially deadly, systemic infection characterized by painful involuntary contraction of skeletal muscles. Other symptoms include • Febrile (feverish), irritability, heavy sweating • A stiff neck, a tight jaw (lockjaw) • Facial muscle spasms (risus sardonicus) and difficulty swallowing Tetanus symptoms & signs In advanced stages, tetanus spasms can break bones. Respiratory complications are common and death rates high, especially in children and elderly persons. Risus sardonicus A soldier dying from tetanus. Painting by Charles Bell Opisthotonos (spastic paralysis of the back) Diagnosis of tetanus Diagnosis of tetanus is made on the basis of the clinical disease, and the patient’s history may indicate inadequate immunization. As stated earlier, C. tetani is a common contaminant of wounds and may be found in patients who do not develop tetanus. Hence, isolation of the bacteria from a patient may not be diagnostic. Treatment As soon as clinical tetanus is suspected, steps to neutralize existing toxin and prevent the formation of new toxin must begin. Antitoxin (tetanus immune globulin) should be administered immediately. This will inactivate toxins in the blood. Wounds should be debrided to remove dead tissue or foreign bodies. Antibiotics should be given to inhibit growth of C. tetani. A tetanus toxoid booster immunization should be given to patients who have not received one within the last 5 years. If spasms occur, antispasmodic drugs should be used and respiration maintained by a breathing apparatus if necessary. Prevention Tetanus carries a 35% mortality rate, making prevention very important! The best course is childhood immunizations, with consistent booster doses, and prompt cleaning of wounds with hydrogen peroxide. Bibliography Microbiology: an introduction, 8th ed. Torotra, Funke, Case, ©2004 Pearson Ed. Inc. Biology of microorganisms, 2nd ed. Brock, ©1974 by Prentice-Hall, Inc. Microbiology, 2nd ed. Davis, Dulbecco, Eisen, Ginsberg, Wood, ©1973 by Harper & Row, Publishers, Inc. Microbiology for the Health Sciences, 4th ed. Jensen, Wright, Robison, ©1997 by Prentice-Hall, Inc. Essentials of Human Diseases and Conditions, 2nd ed. Frazier, Drzymkowski, ©2000 by W.B. Saunders Co. Bacteriology Principles and Practice, 6th ed. Bryan, ©1962 by Barnes & Noble Microbes and Man, 4th ed. Postgate, ©2000 by Cambridge University Press A Field Guide to Germs, 1st ed. Biddle, ©1995 by Henry Holt & Co., Inc. Where the Germs Are: A Scientific Safari ©2003 Nicholas Bakalar, published by John Wiley & Sons, Inc.