HOST–MICROBE RELATIONSHIPS AND DISEASE PROCESSES CHAPTER 14

Symbioses Mutualism- Both parties benefit example E. coli in gut Commensalism- One party benefits, other does not example Staph Aureus on skin Photo of mixed bacteria on skin

Symbioses Parasitism Opportunism One party benefits, other harmed Pinworms on anus

Infection and Disease Contamination-organisms present Infection- organisms multiply Disease- disturbance of health

Pathogenicity Concepts Pathogenicity- capacity to produce disease Virulence/Avirulence - intensity of disease E. coli k12 nonpathogenic E. coli O157:H7 = pathogenic

Normal Microflora Populations Resident Transient

Extend normal flora to outcompete pathogens - probiotics Extend normal flora to outcompete pathogens

Koch’s Postulates 1. specific causative agent must be observed 2. The agent must be isolated and grown in pure culture. 3. Hosts must get the same disease when inoculated. 4. The agent must be reisolated and show to be the same causative agent.

Satisfying Koch’s Postulates

Kinds of Disease Infectious/Non-infectious-caused by organism Communicable/Non-communicable Pneumonia / Emphysema Can be transmitted or not HIV / ulcer

How Microbes Cause Disease Direct Action- adherence, colonization, enzyme action Bacterial Toxins- exotoxins, endotoxins, Cytopathic Effects - hemolysis, loss of membrane integrity Cholera, botulism Salmonella, Staph

Hemolysis Alpha-green halo hemoglobin oxidation Beta - complete hemolysis agar clearing Gamma - no hemolysis or discoloration Blood agar with 3 organisms

Virulence Factors

Botox Excitation signals from the central nervous system Muscle Normal Acetylcholine (A) induces contraction of muscle fibers Botulism Botulinum toxin, , blocks release of A, inhibiting contraction

Tetanus Inhibitory Interneuron Excitation signals from the central nervous system Tetanus toxin Muscle Tetanus Tetanus toxin binds to inhibitory interneurons, preventing release of glycine (G) and relaxation of muscle

Table 28-4

Vocabulary Terms Sign Symptom Syndrome Sequelae Acute Chronic Subacute Latent

Vocabulary Terms (2) Local infection Focal infection Systemic infection Septicemia Bacteremia Viremia

Vocabulary Terms (3) Primary infection Secondary infection Superinfection infection with another virus (discuss HIV and CMV) Mixed infection Inapparent (subclinical) infection

Infectious Disease Stages Incubation Prodromal Invasive Decline Convalescence Migraine example

Disease Stages and Microbe Populations

Control of Infectious Disease Drugs Immunization Sanitization Future Challenges

Protection from disease Removal of particles including microorganisms by rapid passage of air over cilia in nasopharynx Lysozyme in tears and other secretions dissolves cell walls Mucus, cilia lining trachea suspend and move microorganisms out of the body Skin is a physical barrier, produces antimicrobial fatty acids, and its normal flora inhibit pathogen colonization Mucus and phagocytes in lungs prevent colonization Blood and lymph proteins inhibit microbial growth Stomach acidity (pH 2) inhibits microbial growth Rapid pH change inhibits microbial growth Normal flora compete with pathogens Normal flora compete with pathogens in the gut Flushing of urinary tract prevents colonization