Chapter 20

CNS

-anxient environment

-Has no normal microbiata

Pathogens may acesss the CNS in several different ways

-Breaks in bones and mengines

-Hospital proceedures

-Travel in peripheal nuerons to your CNS

-Inflammation can affect permebality of blood brain barrier

-Infect and kill cells of the mengiges causes mengitis.

Pathogens enter the brain in two ways

-Infect of the cells of Nervous System: Leprosy and Mengitis

-Bacteria grows elsewhere releases toxins that affects nuerons: Botiulism and Tetanus

Bacterial Mengitis

signs and symptoms:

-Sudden high fever, severe menigeal inflammation, and increase of white blood in the CSF.

-Inflammation is most signs and symptoms.

-Infection of the brain causes encephalitis

-can result in behaviour changes, coma, and death.

-can develop rapdily

Nisseria Menigitdis

-Also known as mengigococus

-Fimbrae, Capsules, and Lipologsaccharides help bacteria attatch to cells.

-Nisseria without these structures are A virulent

-Capsules protect bacteria from phagocyctic lysis

-Blebbing: releases Lipid A into the body: triggers shock, fever, inflammation, and clotting

Streptoccous Pneumoniae

-Leading cause of meningitis in adults.

-Capsules Protect bacteria from digestion by phagocytes.

-Enzymes and Toxins allow the bacteria to counteract immune defenses.

Phosphorylcholine: triggers endoyctosis by cells

Heaemophilus Influenzae

-Phelmorphic Bacilius

-Obligate parasite of humans and some animals.

-Presence of capsules resisting pahgocytosis.

Different Straints of H. Influenzae distingiushed by capsular antigens.

Prior to vaccination most diseases were caused by H. Influenezae type B

Listeria Monocytogenes

-Enters the body in contaiminated food or drinks.

-Rarely pathogenic in healthy adults.

-Meingitis can occur in pregnant women, fetuses, newborns, eldery, or immunocomprised.

-Production of Listeriolysin O protects bacteria from phagocytic digestion.

Streptocccus aggalactiae

-Lancefield group B strepoccocus

-Normal vaginal microbiata in some women.

-Capsules allow bacteria to evade phagocytosis.

-causes bactermia, pnuemonia, and mengitis in newborns.

-Aquired during birth

Pathogensis of Bacterial Mengitis Species

-Other Bacterial mengitis species transmitted via respiratory droplet.

-Bacteria usually spreads from the blood to the mengigies.

-Head or Neck Trauma allows entry of bacteria to the menngiges.

Epidemiology of Bacterial Mengitis Species

-H. Influenzae was leading cause of bacterial mengitis prior to vaccination.

-S. Pneumoniae and N mengitis are the now most prevalant.

-S agalactia is leading cause of mengitis is new borns.

-Listeria is not transmitted among humans expect mother to fetus

Diagnosis, Treatment, and Prevention of Bacterial Mengitis Species

-Diaggnosed is based on symptoms and culturing of the bacteria from CSF.

-Treated with intravenous antimicrobial drugs.

-Admistration of pencilin at birth reduces neonatal mengitis due to S. Alagactiae.

-Invidiuals at risk listeriosis should avoid high risk foods.

Hansen Disease (Leprosy)

Signs and Symptoms:

Turberculoid Leprosy- Non Progressive form of disease, strong cell mediated immune response.

Lepromatous Leprsosy- more virulent form of the disease, well cell mediated response.

Pathogen and Virulence Factors

Mycobacterium Leprae is a caustive agent

Mycolic acid in the cell wall is responsible for several characteristics of the bacterium:

slow growth rate

protection from phagocytic lysis

growth within pahgocytes

resistant to many antimicrobial drugs

Pathogensis

M. Leprae grows best in cooler regions of the body.

M Leprae can live inside infected cells for years

Cell mediated immunity eventually attacks infected cells; May destroy nerves any other tissues.

Epidemiology

Lepromatus Leprossy is becoming more rare.

Transmitted via person to person or breaks within the skin.

-Diagnosis, Treatment, and Prevention

-Diagnosis is based on signs and symptoms.

Confirmed by the presence of acid fast bacili in samples

Treated with multiple antimicrobials.

-Treatment may be life long for some patients

BCG vaccine provides some protection.

Prevent infections by avoiding exposure to the pathogen.

Botulism

Botulism is an intoxication with manifestations

Signs and Symptoms

Food Borne Botulism- progressive paraylysis on both sides of the body, slow recovery from growth of nerve endings.

Infant Botulism: Results from the ingestion of endospores, non specific symptoms.

Wound Botulism: Contamination of a wound by endospores. Symptoms are similar to food borne botulism.

Pathogen and Virulence Factors:
Clostridum Botulism is the causative agent: Gram Positive Endospore forming Baciliusm.

-Common world wide in the soil and water.

-Different straints produce 1 out of 7 nuerotoxins.
Epidemiology:

Infant Botulism is the most common form in the US.

Diagnosis, Treatment, and Prevention.

-Symptoms are diagnostic.

Four ways to approach treat:

Maintain open and functional airways

-Wash Intestinal tract to remove clostridum.

-Administer Botulism Immune Goblin

-Prevented by destroying endospores in containmated Food.

-Infants under 1 year old should not eat containmated honey.

How Botulism toxin acts as nueromuscular junction

1. Normal Neuromuscular junction: A nerve impulse from CNS causes vescicles to be filled with acetyholine to fuse with nueron cytoplasmic membrane releasing ACH to synpatic cleft a series of event leads to contraction of the muscle.

2. Botulism toxin blocks the fusion acetyholine with nueron cytoplasmic membrane which prevents secretion of ACH into the cleft which causes muscles not to contract