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Patho: Infections
Unit 4 Terms
| Question | Answer |
|---|---|
| Pathogenicity | The capacity of a microbe to cause disease |
| Virulence | Degree of pathogenicity |
| What determines virulence | Invasive qualities, e.g., motility or enzymes Toxins Adherence to tissue by pili, fimbriae, specific receptor sites Ability to avoid host defenses |
| Newly emerging diseases | Anti-genetically different forms of common infections such as influenza Spread beyond normal endemic areas |
| “Super infections” | Multi-drug resistant forms of existing diseases ex. TB, Staphylococcus aureus |
| Standard Precautions | used in all settings with all clients when body fluids may be exchanged. ex. gloves, hand washing, sometimes mask |
| Specific Precautions | Specific precautions in clients diagnosed with a particular infection. These are used in addition to standard precautions. |
| BREAKING THE CHAIN what could prevent transmission through direct contact | barriers mask, gloves, glasses, gown, etc |
| BREAKING THE CHAIN what could prevent transmission through indirect contact | hand hygiene and disinfecting |
| BREAKING THE CHAIN what would help prevent an infection from entering a susceptible host? | current immunizations |
| BREAKING THE CHAIN what would help prevent an infection from leaving a reservoir and exiting the body? | limiting numbers, barriers |
| How could you help break the cycle of infection? | Locate/remove/isolate the reservoir. Identify/restrict access to contaminated items. Reduce contact between infected persons. Block portals of exit and entry. Remove or block modes of transmission. Reduce host susceptibility by immunizations. |
| Incubation period | Time between entry of organism into the body and appearance of clinical signs of disease Vary considerable with different organisms |
| Prodromal period | Fatigue, loss of appetite, headache Nonspecific – “coming down with something” More evident in some infections that other |
| Ways to sterilize equipment | Chemicals Heat & pressure in an autoclave NOTE: Equipment must be cleaned prior to sterilization, or it will remain contaminated! |
| Antiseptics are - | used on the skin and tissues to clean. |
| Disinfectants are - | used on surfaces or objects to clean |
| Acute Infection | Infectious disease fully develops. Clinical manifestations reach peak. Length depends on virulence of organism |
| Chronic Infection | Infection is not totally eradicated. Organism continues to reproduce in body. Clinical signs are present and usually milder than in acute infection. Periodic acute episodes may recur. |
| Subclinical infection | Microbe reproduces in body but does not cause signs or symptoms. |
| Bacteremia | Bacteria in blood Small numbers for a short period of time Destroyed by circulating phagocytes but may lead to septicemia |
| Septicemia, Sepsis, Septic | Bacteria circulating and reproducing in bloodstream |
| Local signs of inflammation | Pain, swelling, redness, warmth If bacterial – purulent exudate If viral – serous, clear exudates |
| Systemic signs of inflammation | Fever may be present. Fatigue and weakness Headache Nausea |
| Normal Leukocyte count | 4,000-11,000 |
| Leukopenia | Leukocytes <4,000 |
| Leukocytosis | Leukocytes >11,000 |
| Normal ESR (Erythrocyte Sedimentation Rate) | 15-30 mm/hr |
| ESR of someone with an infection | > 30 mm/hr |
| What is C-reactive Protein? (CRP) | produced by liver, indicates level of inflammation |
| Differential WBC | measures percentage of each type of WBC |
| Culture and staining techniques | identifying if something is gram positive or negative |
| Guidelines for Drug Therapy | Drugs should be as directed and used COMPLETELY! If symptoms continue without reduction, contact pharmacist or physician. Do not use drugs prescribed for other patients. If drug resistance is known, use multi-drug therapy. |
| Antibiotic | Drugs derived from organisms |
| Antimicrobials | Antibacterial, Antiviral, Antifungal |
| Bactericidal | Drugs destroy organism |
| Bacteriostatic | Decrease rate of reproduction |
| Broad spectrum | Effective against both gram-positive and gram-negative |
| Narrow spectrum | Effective against either gram-positive or gram-negative organisms |
| First and second-generation drugs | First generation: original drug class Second generation: later version, which may be more effective, more tolerable, or more easily administered |
| How does Penicillin work? | Interference with bacterial cell wall synthesis |
| How does Polymyxin work? | Increase permeability of bacterial cell membrane |
| How does Tetracycline work? | Interference with protein synthesis |
| How does Sulfonamides work? | Interference with the synthesis of essential metabolites |
| Mode of Action of Antivirals | Blocking entry into host cell Inhibiting gene expression Inhibiting assembly of the virus |
| What is a Microorganisms | Small living forms Include bacteria, fungi, protozoa, viruses Many can grow in artificial culture medium Can be Non-pathogenic orPathogenic |
| Bacteria | Classified as prokaryotes No nuclear membrane – no nucleus Function metabolically and reproduce Complex cell wall structure Do not require living tissues to survive Vary in size and shape Reproduce by Binary Fission |
| Shape of Bacilli | Rod-shaped |
| Shape of Spirochetes | Spiral |
| Shape of Cocci | Spherical |
| What color do Gram-positive bacteria appear under the microscope? and why? | purple due to retention of stain from thick peptidoglycan layer in cell wall |
| What color do Gram-negative bacteria appear under the microscope? and why? | red due to lack of retention of stain from thin peptidoglycan layer in cell wall |
| Examples of gram-positive | Common antibiotics are used to treat Gram-positive Ex. Staph, strep |
| Examples of gram-negative | Can quickly develop resistance to antimicrobial agents through chromosomal mutations and gene transfers. Ex. E. coli, Pseudomonas, Salmonella |
| Other Bacterial Structures: External capsule or slime layer | Found in some Outside the cell wall Offers additional protection |
| Other Bacterial Structures: Flagella | One or more attached to cell wall Provide motility for some species |
| Other Bacterial Structures: Pili or fimbriae | Tiny hairlike structures – found in some bacteria Assist in attachment to tissue Transfer of DNA to another bacterium |
| Cell membrane | ALL BACTERIA Inside the bacterial cell wall Selectively permeable |
| Bacteria Cytoplasm contains: | Chromosome One long strand of DNA Ribosomes and RNA Plasmids DNA fragments; non-chromosomal; exchange DNA during conjugation |
| Exotoxins | Proteins produced INSIDE the pathogen and secreted into the surrounding medium. Usually produced by gram-positive bacteria |
| Endotoxins | Present in the cell wall of gram-negative bacteria Released upon death of bacterium Vasoactive compounds that can cause septic shock |
| Enzymes | Damage tissues and promote spread of infection |
| Spores | Dormant form of bacterium that are produced as a survival mechanism when conditions are unfavorable. Highly resistant to heat and disinfectants Can remain viable for thousands or millions of years |
| Viruses | Small obligate intercellular parasites Protein coat or capsid - comes in various shapes and sizes Can change (mutate) quickly Nucleic acid DNA or RNA |
| Type of Helical Virus | Tobacco Mosaic Virus Spiral shaped |
| Type of Polyhedral Virus | like adenoviruses shaped like a dodecahedron (20-sided dice) |
| Type of Spherical Virus | like COVID, Flu, HIV |
| Types of Complex Viruses | Bacteriophage -affects bacterial cells |
| If there is an Active Viral Infection, it is said to be in what type of reproductive cycle. | Lytic Cycle |
| If there is an Latent Viral Infection, it is said to be in what type of reproductive cycle. | Lysogenic Cycle |
| When would you see symptoms of an active viral infection | 3-14 days |
| When would you see symptoms of an latent viral infection | months to years |
| Example of viruses that go through lytic cycle | COVID, flu |
| Example of viruses that go through lysogenic cycle | HIV, Herpes, shingles |
| Main difference between the process between active and latent viral infection. | Active will assemble new viruses right away, then burst out of the cell. Latent is when the viral DNA incorporates into the host and replicates when the host goes through binary fission. |
| What is unique about Chlamydia, Rickettsiae, Mycoplasmas | They are bacteria that have characteristics of viruses (require a host) |
| What does Obligate Intracellular Parasite mean? | rely solely on intracellular resources of another organisms to replicate, cannot grow in artificial medium |
| What is Chlamydia | Common cause of sexually transmitted infection Can result in infertility |
| What is Rickettsiae | Gram-negative Transmitted by vector-borne (lice, fleas, mites, ticks) |
| What is Mycoplasmas | Lack cell wall Airborne (respiratory droplets) Cause of atypical type pneumonia |
| What is Fungi? | Eukaryotic organisms Found throughout environment On animals, plants, humans, food Fungal or mycotic infection Only a few are pathogenic. |
| Common name for Tinea Pedis | Athletes foot - fungus |
| What is Candida | opportunistic fungal infection, causes thrush and vaginitis |
| Common name for Tinea Corporis | ringworm - fungus |
| What is Histoplasmosis | fungal infection that causes neurologic disease and can be transmitted to embryo/fetus if woman infected |
| What is Pneumocytosis carinii | Opportunistic organism causing pneumonia Has some characteristics of fungi and some of protozoa |
| Protozoa | A subgroup of Protista Eukaryotic forms Unicellular, lack cell wall Many live independently, others are obligate parasites (require a host) Pathogens are usually parasites. |
| What is Trichomoniasis | protozoa - most prevalent nonviral STI |
| What is Malaria | vector-borne (mosquitos) - protozoa |
| What is Amebic dysentery | intestinal infections spread through human feces in contaminated food/water - protozoa |
| Helminths | (Flat or Round Worms) Are not microorganisms - Parasites May be small or up to 1 meter Life cycle include Ovum, larva, adult Enter body through skin or by ingestion Common in young children |
| Pinworms: | ovum inhaled in dust in fecally contaminated areas. Common in kids worldwide |
| Hookworms: | Larvae enter skin from fecally contaminated soil in tropical areas |
| Tapeworm: | Most common form is transmitted by larvae in undercooked pork |
| Ascaris/Giant Round Worm: | Ingested with food that has been grown in feces-contaminated soil or prepared with hands that have been in feces-contaminated soil |
| Prions | Protein-like agents that change the shape of proteins within host cells Transmitted by contaminated tissues (meat) or infected blood or donor organs Cause degenerative disease of the nervous system |
| What is Creutzfelt-Jacob disease? | variant of the human prion disease Both rapidly progressive and fatal |
| What is Resident Flora | Many areas of the body have a resident population of mixed microorganisms Ex: Skin, Nasal cavity, Mouth, Gut, Vagina, Urethra |
| Infection | organism can reproduce in or on body’s tissues |
| Sporadic | occurs in a single individual |
| Endemic | continuous transmission within a population |
| Epidemic | higher than normal transmission or spread to new geographical area |
| Pandemic | Transmission has occurred on most continents |
| How many links are in the chain of infection? | 6 |
| Agent | the microbe causing the infection |
| Reservoir | Environmental source such as contaminated soil Infected person or animal Source of infection, Person with active infection, Person who is asymptomatic |
| Carrier | A type of Reservoir where a person may never develop the disease but still is a carrier, person with subclinical signs of the disease |
| Portal of exit | Means by which the agent leaves the reservoir |
| Mode of transmission | Method by which the agent reaches new susceptible host |
| Portal of entry: | Access to new host |
| Susceptible host: | Susceptibility will depend on health status, immunity, age, nutrition, etc. |
| Direct contact | No intermediary Touching infectious lesion, sexual activity Contact with infected blood or bodily secretions |
| Indirect contact | Involves intermediary object or organism Contaminated hand or food Fomite or inanimate object |
| Droplet transmission | Respiratory or salivary secretions are expelled from infected individual |
| Aerosol transmission | Involve small particles from the respiratory tract Suspended in air and can travel farther than droplets |
| Vector borne | Insect or animal is an intermediate host |
| Formite | inanimate object |
| Nosocomial Infections | infections that occur in health care facilities: Hospitals, nursing homes, physician’s offices, dental offices |
| What percent of patients acquire an infection in the hospital? | 10% - 15% |
| Reasons how nosocomial infections occur. | Many microbes present Patients with undiagnosed infectious disease Shared environment Treatments may cause weakened immune systems. Many health care workers, fomites act as reservoirs |
| Host Resistance | the ability of an organism to limit the number of pathogens it's exposed to. |
| Microbial virulence | the ability of a microbe to cause damage to a host. |
| Factors that Decrease Host Resistance | Age (infants and elderly) Pregnancy Genetic susceptibility Immunodeficiency Malnutrition Chronic disease Severe physical or emotional stress Inflammation or trauma Impaired inflammatory responses |
| Factors that Increase Bacterial Virulence | Invasive qualities, e.g., motility or enzymes Toxins Adherence to tissue by pili, fimbriae, specific receptor sites Ability to avoid host defenses |
Created by:
adittrich
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