CH5 - Infection Flashcards
A state of tissue destruction resulting from invasion of microorganisms:
Infection
Any microorganisms that can cause a disease ➡️ must be able to bind to human host cells
▫️directly destroys host cells
▫️interferes host cells metabolic capabilities
▫️exposes host cell to toxins
Pathogens
pathogenicity- qualities that allow microorganism to promote a disease.
▫️virulence ▫️infectivity ▫️toxigenicity ▫️antigenicity ▫️antigenic variability ▫️pathogenic defense mechanisms
The majority of _____ are harmless to humans and may even be beneficial to our lives ➡️ could not survive w/o them
▫️antibiotic
▫️insulin
▫️food industry: in bread making, yogurt, cheese
Microorganisms
The beneficial population of microbes (bacteria, viruses, Protozoa) that live in and on our bodies ▫️nose, pharynx ▫️mouth, colon, rectum ▫️vagina ▫️distal urethra and perineum
Normal flora
Manifestation of infection - Systemic
▫️fever ▫️weakness ▫️headache ▫️malaise ▫️anorexia ▫️nausea
Manifestation of infection - Local
▫️heat ▫️incapacitation ▫️Pain ▫️edema ▫️redness ▫️lymphadenitis ▫️purulent exudate
Classes of microorganisms
▫️bacteria
▫️viruses
▫️Protozoa
▫️fungi
Sterile areas of the body:
▫️blood, CSF ▫️Lungs ▫️stomach ▫️ uterus, Fallopian tubes, ovaries ▫️bladder and kidneys
▫️A single-called microorganisms
▫️do not require living tissues to survive
▫️vary in size and shape
▫️divide by binary fission - can occur outside of host cells
Components: cell membrane, indiscrete nucleus, cytosol
Bacteria - a full living cell
can essentially duplicate
Living requirements of bacteria
▫️moisture ▫️food ▫️electrolyte balance ▫️adequate temperature ▫️adequate O2 ▫️adequate pH ▫️adequate light
released from cell walls of bacteria when they are lysed.
Endotoxins
A unicellular organisms that do not require living tissue to survive. They vary in size, shape, and arrangement
Bacteria
A bacterium has one or two types of cell walls, which differ in chemical composition.
Gram-positive or gram-negative
Some bacteria secrete toxic substances, toxins, and enzymes.
Toxins consists of two types:
Exotoxins and endotoxins
A latent form of bacterium with coating that is highly resistant to heat and other adverse conditions. bacteria resume a vegetative state and reproduce.
Ex. Tetanus and botulism
Spores
Are produced by some bacteria and are a source of damage to the host tissues or cells. promote spread of infection
Ex: hemolysin
Enzymes
A non-living intracellular parasites -requires host cells to survive
▫️Viruses
Viruses consists of:
▫️protein coat or capsid (comes in many shapes sizes and undergoes change relatively quickly in the evolution of the virions)
▫️ genetic material (either DNA or RNA)
A large microorganisms found throughout environment
▫️on animals, plants, humans, food
▫️unicellular ➡️ yeast
▫️multicellular ➡️ moods and mushrooms
Fungi
Fungi infections are termed ?..
▫️mycoses or mycotic infections
Only few fungi are pathogenic, causing infection on the skin or mucous membranes. such as:
▫️pneumonia ▫️thrush mouth ▫️ring worm (scalp) ▫️vaginitis (candidiasis) ▫️athletes foot
Benefits of Fungi:
▫️major role in decomposition of dead matter, providing nutrients for other organisms
▫️antibiotic drugs (e.g. penicillin)
▫️food production (yogurt, bread)
▫️also keep bacteria, viruses at bay (ex.resident flora)
Complex unicellular organisms found in water, soil ➡️ important in food chain as producers and decomposers
Transmission occurs through contaminated food or water, sexual contact,mor a vector.
Protozoa
Common protozoal diseases:
▫️malaria
▫️traveler’s diarrhea
▫️dysentery
Phases of Acute infection:
🔺infection is established if host’s defense s are insufficient to destroy pathogens
- Exposure
- Incubation
- Prodrome
- Clinical illness
- Convalescence
complications of infection:
▫️septicaemia
▫️chronic infection
Common Laboratory and Diagnostic test to Detect infection
- WBC count
- Serum antibody levels
- Cultures
- Sensitivities
elevation in WBC w/c may indicate an infectious process, often bacterial in origin
Leukocytosis
decrease in WBC, which may indicate a viral infection or a problem with suppression of WBC production
Leukopenia
A lab test that identifies w/c anti microbial drugs would be most effective for a specific pathogen
Sensitivities
Certain factors decrease host resistance to infection
▫️age ▫️genetic susceptibility ▫️immunodeficient individual ▫️severe physical and emotional stress ▫️malnutrition
Modes of transmission of infectious Agents:
▫️direct contact
▫️droplet transmission
▫️airborne transmission
▫️vector transmission
