Infectious Processes Patho Flashcards
Chain of Transmission
Infectious Agent -> Reservoir -> Portal of Exit -> Mode of Transmission -> Portal of Entry -> Host
- Chain can be broken at any point
Agent/Pathogen/Microbe
Disease-causing organism (infectious)
Reservoir
- Place where pathogen lives and reproduces (human)
- Destroy: mosquito eradication, garbage disposal, sewage treatment
Portal of Exit
- How organism gets out of reservoir
- Block: masks, gloves, isolation, condoms
Mode of Transmission
- How organism is spread (surfaces, fluids, vectors)
- Block: sterile technique, hand washing, body substance isolation
Portal of Entry
- How agent gets into host
- Block: masks, gloves, condom use
Host
- Individual at risk for contracting organism
- Reduce susceptibility: vaccination, optimal rest and nutrition
Epidemiology
Host -> vector -> agent and environment
3 types of relationship btw host and pathogen
- Symbiosis
- Mutualism
- Commensalism
Symbiosis
Benefit to human and no harm to microorganism
Mutualism
Benefit human and microorganism
Commensalism
Benefit to microorganism and no harm to human
Pathogenicity
Benefits organism and harms human
Immunogenicity
Ability of microbe to induce immune response
Host Characteristics
- Physical and Mechanical Barriers: epithelial cells (protective), mucus membranes, coughing/sneezing/peeing/pooping, sweat/saliva/tears
- Risk Factors: age, nutritional status, chronic illness, immunosuppression, chronic stress
- Immunization: directly or by herd immunity
Host Defenses
- Physical & Mechanical Barriers
- Innate inflammatory response
- Adaptive immunity response
2 classifications of microbes
- Normal microbial flora: beneficial
- Others: pathogenic/disease-causing
Characteristics of pathogenic microbes
- Adherence (stickiness, makes it harder for our defenses to attack)
- Invasive (how microbes get access into host and survive)
- Endotoxins and Exotoxins
- Bacterial enzymes (degrade tissue or dissolve blood cells)
- Antiphagocytic factors (outside coating to disguise and get rid of)
- Endospores (internal store of resting state is resistant to heat and chemicals)
- Mobility (flagellum to move toward nutrients or away from repellants)
- Antimicrobial resistance (mutation that allows microbe to survive in presence of antibiotic)
Bacteria Characteristics
- Single celled, rigid wall, no internal organelles
- Shapes: cocci (spherical), bacilli (rod or comma), spiral (twist)
- Gram stain tells us about cell wall components: positive (dark blue), negative (pink), acid fast (resist stain)
- O2 requirements: aerobic or anaerobic
Fungi Characteristics
- Eukaryotic, contains organelles, form complex structures, thick rigid cell wall
- Many are part of normal flora (become a problem when defense mechanisms are compromised)
- Infections caused by fungi = mycoses, mycotic infections
- Locations: superficial and cutaneous, subcutaneous, systemic
Parasite Characteristics
- Establish themselves with another organism and benefit from the other
- Types: protozoa (single-celled), helminthes (roundworms and flatworms), arthropods (invertebrate animals with jointed appendages)
- Sites: skin and GI tract
Virus Characteristics
- Most common afflictions
- Simple microorganisms: no metabolism, incapable of independent reproduction
- Need to infect a permissive host to replicate, turn cells into replication machine
- Can bypass many defense mechanisms because they develop intracellularly (protected)
Incubation
- Clinical Infectious Disease Stage 1
- period from initial exposure to onset of first symptoms
- still infectious
Prodromal
- Clinical infectious disease stage 2
- occurrence of initial symptoms (mild)
