Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
TOPIC 10. MICROBIAL DISEASES OF THE NERVOUS SYSTEM (Chapter 22) 1. STRUCTURE AND FUNCTION OF THE NERVOUS SYSTEM (Figure 22.1, 22.2 pg 616, 617) a) The nervous system has two parts: a. The central nervous system (CNS): brain and the spinal cord. b. The peripheral nervous system (PNS): nerves that branch from the CNS. b) The CNS is covered by three membranes called meninges: a. Dura mater (outermost), b. Arachnoid mater (middle), c. Pia mater (innermost). c) Cerebrospinal fluid (CSF): a. Circulates between the arachnoid mater and the pia mater, in the subarachnoid space. b. This has little complement or Ab and few phagocytes, so bacteria in the CSF can multiply quickly and easily. d) The blood-brain barrier: a. Normally prevents many substances, such as antibiotics (unless lipid soluble), from entering the brain. b. Inflammation of the brain changes the blood-brain barrier so that antibiotics can cross it, thus allowing us to treat infections with drugs. e) Microbes can enter the CNS through: a. Trauma (e.g. skull fracture or spinal tap), b. Along peripheral nerves, c. Through the bloodstream and lymphatic system. f) An infection of the meninges is called meningitis. An infection of the brain is called encephalitis. 2. BACTERIAL DISEASES OF THE NERVOUS SYSTEM a) Infrequent but serious. A. BACTERIAL MENINGITIS (Table 22.1 pg 617) a) Symptoms : a. Initial symptoms include fever, headache and stiff neck. b. This is followed by nausea and vomiting. c. Eventually convulsions and coma. d. If death occurs, it is quick, caused by shock and inflammation from endotoxins from gram-negative bacteria and cell wall fragments from gram-positive bacteria. e. Survivors may suffer neurological damage. b) Causes : a. Three bacterial species cause more than 70% of the meningitis cases and 70% of the related deaths. These are encapsulated bacteria: 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
i. Haemophilus influenzae, ii. Streptococcus pneumoniae, iii. Neisseria meningitidis. i) Haemophilus influenzae Meningitis (Figure 22.3 pg 618) a) H. influenzae (gram-negative aerobe) is part of the normal microbiota of the throat. b) Occasionally it enters the blood stream and can cause: a. Meningitis b. Otitis media c. Pneumonia d. Epiglottitis c) H. influenzae requires blood factors for growth (hemo = blood; philus = love). d) There are six types of H. influenzae based on polysaccharide capsule differences. a. H. influenzae type b (Hib) is the most common cause of meningitis in children under age 4. b. A vaccine is available and use of it has decreased the incidence of meningitis in children under five years of age by 99% in the U.S. ii) Neisseria Meningitis (Meningococcal Meningitis) a) N. meningitidis (gram negative aerobic coccus) causes meningococcal meningitis. b)
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 8


This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online