Medical Technology Department, Faculty of Science, Islamic University-Gaza MB M ICRO B IOLOGY Dr. Abdelraouf A. Elmanama Ph. D Microbiology 2008 Chapter 22 Microbial Diseases of the Nervous System

2008 Microbes enter the nervous system via: Skull or backbone fractures Medical procedures Along peripheral nerves Blood or lymph

2008 The Nervous System Figure 22.1

2008 Microbial Diseases of the Nervous System Bacteria can grow in the cerebrospinal fluid in the subarachnoid space of the CNS The blood brain barrier (capillaries) prevents passage of some materials (such as antimicrobial drugs) into the CNS Meningitis Inflammation of meninges Encephalitis Inflammation of the brain

2008 The Meninges and Cerebrospinal Fluid Figure 22.2

2008 Fever, headache, stiff neck Followed by nausea and vomiting May progress to convulsions and coma Diagnosis by Gram stain of CSF Treated with cephalosporins Bacterial Meningitis

2008 Bacterial Meningitis Table 22.1

2008 Occurs mostly in children (6 months to 4 years) Gram-negative aerobic bacteria, normal throat microbiota Capsule antigen type b Prevented by Hib vaccine Haemophilus influenzae Meningitis

2008 Haemophilus influenzae Meningitis Figure 22.3

2008 N. meningitidis Gram-negative aerobic cocci, capsule 10% of people are healthy nasopharyngeal carriers Begins as throat infection, rash Serotype B is most common in the U.S. Vaccine against some serotypes is available Neisseria Meningitis, Meningococcal Meningitis

2008 Neisseria Meningitis, Meningococcal Meningitis Figure 22.4

2008 Gram-positive diplococci 70% of people are healthy nasopharyngeal carriers Most common in children (1 month to 4 years) Mortality: 30% in children, 80% in elderly Prevented by vaccination Streptococcus pneumoniae Meningitis, Pneumococcal Pneumonia

2008 Listeria monocytogenes Gram-negative aerobic rod Usually foodborne, can be transmitted to fetus Reproduce in phagocytes Listeriosis

2008 Listeriosis Figure 22.5

2008 Clostridium tetani Gram-positive, endospore-forming, obligate anaerobe Grows in deep wounds Tetanospasmin released from dead cells blocks relaxation pathway in muscles Prevention by vaccination with tetanus toxoid (DTP) and booster (dT) Treatment with tetanus immune globulin Tetanus

2008 Tetanus Figure 22.6

2008 Clostridium botulinum Gram-positive, endospore-forming, obligate anaerobe Intoxication due to ingesting botulinal toxin Botulinal toxin blocks release of neurotransmitter causing flaccid paralysis Prevention: Proper canning Nitrites prevent endospore germination in sausages Botulism

2008 Treatment: supportive care and antitoxin Infant botulism results from C. botulinum growing in intestines Wound botulism results from growth of C. botulinum in wounds. Botulism

2008 Type A 60-70% fatality Found in CA, WA, CO, OR, NM Type B 25% fatality Europe and eastern U.S. Type E Found in marine and lake sediments Pacific Northwest, Alaska, Great Lakes area Botulism

2008 Diagnosis Figure 22.7

2008 Mycobacterium leprae Acid-fast rod that grows best at 30°C Grows in peripheral nerves and skin cells Transmission requires prolonged contact with an infected person Tuberculoid (neural) form: Loss of sensation in skin areas; positive lepromin test Lepromatous (progressive) form: Disfiguring nodules over body; negative lepromin test Leprosy

2008 Leprosy Figure 22.8

2008 Poliovirus Transmitted by ingestion Initial symptoms: sore throat and nausea Viremia may occur; if persistent, virus can enter the CNS; destruction of motor cells and paralysis occurs in <1% of cases Prevention is by vaccination (enhanced-inactivated polio vaccine) Poliomyelitis

2008 Poliomyelitis Figure 22.10

2008 Transmitted by animal bite Virus multiplies in skeletal muscles, then brain cells causing encephalitis Initial symptoms may include muscle spasms of the mouth and pharynx and hydrophobia Furious rabies: animals are restless then highly excitable Paralytic rabies: animals seem unaware of surroundings Preexposure prophylaxis: Infection of human diploid cells vaccine Postexposure treatment: Vaccine + immune globulin Rabies virus (Rhabdovirus)

2008 Rabies virus (Rhabdovirus) Figure 22.11

2008 Rabies virus (Rhabdovirus) Figure 22.12

2008 Arboviruses are arthropod-borne viruses that belong to several families. Prevention is by controlling mosquitoes Arboviral Encephalitis

2008 Soil fungus associated with pigeon and chicken dropping Transmitted by the respiratory route; spreads through blood to the CNS Mortality up to 30% Treatment: amphotericin B and flucytosine Cryptococcus neoformans Meningitis (Cryptococcosis)

2008 Cryptococcus neoformans Meningitis (Cryptococcosis) Figure 22.14

2008 Trypanosoma brucei gambiense infection is chronic (2 to 4 years) T. b. rhodesiense infection is more acute (few months) Transmitted from animals to humans by tsetse fly Prevention: elimination of the vector Treatment: Eflornithine blocks an enzyme necessary for the parasite Parasite evades the antibodies through antigenic variation African Trypanosomiasis

2008 African Trypanosomiasis Figure 22.15

2008 Protozoan infects nasal mucosa from swimming water Naegleria fowleri Figure 22.16

2008 Caused by prions Sheep scrapie Creutzfeldt-Jakob disease Kuru Bovine spongiform encephalopathy Transmitted by ingestion or transplant or inherited Chronic, fatal Transmissible Spongiform Encephalopathies

2008 Transmissible Spongiform Encephalopathies Figure 22.17a