Diseases of the Nervous System Caused by Bacteria

Microbiology

Diseases of the Nervous System Caused by Bacteria

Jennifer and Jamie

4/18/2012

Nervous System Diseases Caused by Bacteria:

Microbial diseases affecting the nervous system tend to be severe because of the vital tasks performed by the brain, spinal cord, and peripheral and cranial nerves. Infections can occur in the nervous tissue or in the covering membranes called meninges. The nervous system has no natural micro biota, it is sterile. Diagnostic test for diseases of the nervous system often involve examination of the cerebrospinal fluid, and antibiotic therapy must use drugs that pass the blood-brain barrier. We will discuss six of the most severe bacterial infections of the nervous system.

The Menigococcal Meningitis (bacterial meningitis, epidemic meningitis) is caused by a gram-negative diplococcus, which is aerobic and non-motile, Neisseria Meningitidis, also called Meningococcus. It is transmitted by respiratory droplets such as coughing and sneezing, it can also be transmitted by chewing on toys and pens. N. Meningitidis often inhabits the nasopharynx without evidence of disease. The organism is believed to possess endotoxins that account for the symptoms associated with meningitis. With symptoms that occur fast including severe headaches, high fever, pain and stiffness of the neck, back, and shoulders and nausea follows soon after all the initial symptoms. Skin lesions have been noted is 50% of patients. If someone is to survive the disease they will have life changing effects that can include deafness, mental retardation, and behavior defects. Examination of the cerebrospinal fluids reveals Gram-negative diplococcic. The adrenal glands may be involved (Waterhouse-Friderichen syndrome). A range of antibiotics can treat the infection, including penicillin, ampicillin, chloramphenicol, and ceftriaxone. As for prevention there are three vaccines available.

Haemophilusmeningitis is caused by Haemophilus Influenzaetype B. H. Influenzae was discovered in 1892 by Richard Pfeiffer during an influenza pandemic, resulting in the bacteria being mistakenly named after influenza. This organism is a Gram-negative, small rod, which is usually aerobic that typically affects children during the first few years of life. H .Influenzae may be transmitted through contact with mucus or droplets from the nose and throat (exhaled droplets). Normally H. Influenzae lives in their host without causing disease. The incubation period is unknown. Nerve disorder, fever, and possible mental retardation result from Haemophilusmeningitis. H. Influenzae is resistant to the penicillin family making cefotaxime and ceftriaxone the most used. Rifampin may be used as preventive treatment for someone that has been exposed. The HIB vaccine is used to provide immunity.

Listeriosis is caused by a small, Gram-positive bacterium called Listeria Monocytogenes, named for Joseph Lister. L. Monocytogenes was first described by E.G.D. Murray in 1926 based on six cases of sudden death in young rabbits. Murray referred to the organism as Bacterium Monocytogenes before Harvey Pirie changed the genus name to Listeria in 1940. However it was not until 1981 when it was associated with foodborne illnesses. L. Monocytogenes can be resistant to the effects of freezing, drying, and heat; surprisingly well for a non-spore forming bacterium. Listeriosis is the third leading cause of meningitis. It can be transmitted to newborns transvaginally. The disease is transmitted by unpasteurized or improperly pasteurized milk and cheese products, as well as from animals.

Leprosy is considered a disease of the nervous system because the bacilli destroy the peripheral nerves in the skin. Thus affected, the patient cannot sense environmental changes, and injury to the skin results. Deformed hands and feet and eroded bones, fingers, and toes are seen in the disease. In tuberculoid leprosy, skin pigments are lost. In lepromatous leprosy, skin nodules called lepromas disfigure the skin. The incubation time is roughly three to six years. Leprosy is caused by an acid-fast bacillus called Mycobacterium leprae. This disease is known Hansen's disease. It was first discovered in 1873 by Gerhard Armauer Hansen. He was searching for the bacteria in the skin nodules of patients with leprosy. Armadillos and humans are the only known organisms capable of contracting M. Leprae. Scientists are unaware of how the disease in contracted. Some say that it has to do with prolonged contact with an infected person, usually through bodily fluids. While other say that genetics play a big role. It has been found that only 5% of the human population is susceptible to the disease. While the skin was thought to be the best entry route of the disease, studies are showing that it is more likely through the respiratory tract. Dapson is used for therapy.

Tetanus is caused by the soilborne, anaerobic, gram-positive rod Clostridium Tetani. Spores enter a wound, and then germinate