Class 3 Flashcards
All living creatures share 2 basic objectives in life which are?
1) survival
2) reproduction
All living creatures share 2 basic objectives in life:
1) survival
2) reproduction
to satisfy these goals, organisms must do what?
Extract from the environment essential nutrients.
-can benefit both organisms or produce harmful &
potentially lethal consequences.
Consequences of these invasions are called _______________.
infectious diseases
What is a host?
any organism capable of supporting nutritional & physical growth requirements of another organism.
What is infectivity?
ability of organism to enter, multiply & survive in host
What is infection?
presence & multiplication within host that results in injury to host
What is colonization?
act of establishing a presence within a host
T/F All interactions between microorganisms and humans are detrimental?
False - NOT all interactions between microorganisms and humans are detrimental
What is microflora?
multitude of non-harmful bacteria that inhabit internal & external exposed surfaces of human body.
Microflora can be found in what?
• Skin
• Nose/Pharynx
• Mouth
• Colon/Rectum
• Vagina/Distal Urethra/Perineum
What is commensalism?
Colonizing organism benefits & host is NOT adversely affected by it
What is Mutualism?
Colonizing organism & host both derive benefits
What is Parasitic?
Colonizing organism benefits & host gains nothing or sustains injury
Infectious disease can vary in severity and can be due to
______________________ and ______________________________.
• host health
• virtulence of the organism
What is Virulence?
Disease producing potential of invading organism.
__________________ are an example of a highly virulent organism and are rarely found in the host when there is no disease.
Pathogens
What are Saprophytes?
Harmless, free living organisms that obtain nutrition from dead or decaying organic materials in environment.
What is an Opportunistic Pathogen?
An organism which is capable of producing an infectious disease only when health & immunity of host have been severely compromised.
What are Prions?
• protein particles that lack any kind of demonstrable genetic material.
• mutated forms of normal host protein.
• may affect other normal proteins & alter them.
• aggregate in brain & form plaques.
• have been identified in number of incurable &
transmissible degenerative neurological diseases
• defective protein may be inherited.
• Transmissible degenerative neurological diseases are
all characterized by slowly progressive, non inflammatory neuronal degeneration, leading to loss of coordination (ataxia), dementia & death ranging from months to years.
• Current antimicrobial agents are useless against them
therefore treatment is palliative.
Prions have been identified in a number of incurable &
transmissible degenerative neurological diseases such
as?
• Creutzfeldt-Jakob disease
• Kuru
• Mad Cow disease
Rickettsia, Chlamydia, Coxiella, Mycoplasma are organisms that combine characteristics of ______________ and ______________.
viruses and bacteria
What is Rickettsiacecae?
- Live inside host cell since they rely on host cell for vitamins & nutrients
- Transmitted by insect vectors/bite of arthropod (fleas, ticks & lice)
- Produce number of potentially lethal diseases
Ex. Rocky Mountain Spotted Fever & Epidemic Typhus.
What is Chlamydiaceae?
• Scavenge intermediates of energy metabolism, like ATP.
• Transmitted directly between susceptible vertebrates
without intermediate arthropod host.
Ex. Sexually transmitted infection Chlamydia which can lead to pelvic inflammatory disease & sterility in women. Infants born to infected mothers can develop eye infections & pneumonia.
What is Coxiella?
• Infects variety of animals & in humans produces
illness often called Q fever, illness that presents with flu-like symptoms, & cause progress to become systemic
affecting heart, lungs, & GI.
What is Mycoplasma?
• Capable of independent replication.
• Resistant to cell-wall binding antibiotics like Penicillin.
• In humans, they are commensals but some species are
capable of producing serious diseases including pneumonia, genital infections & maternally transmitted respiratory infections to infants with low birth weight.
What is fungi?
• free living saprophytes found in every habitat on earth.
• some are part of normal human microflora.
• few are capable of causing disease in humans & when they do, they are infections of skin & subcutaneous tissue.
• serious infections are usually initiated through puncture wounds or inhalation.
• can cause life threatening opportunistic diseases when host has been weakened.
What are the 2 groups of fungi?
- Yeast
- Molds
What is yeast described as?
smooth with a waxy or creamy texture
What are moldes described as?
cottony or powdery texture that can penetrate growth surface or project above
What are yeasts and molds?
• Yeasts & molds produce rigid cell wall layer which makes it not susceptible to effects of antibiotics.
• Can reproduce disease in humans only if they can grow at
temperature of infected body site.
Ex. Athletes Foot- fungal infection, scaly rash, contagious,
OTC meds
What is Candida?
Type of yeast that is commensal flora of skin, mucous membranes & GI tract, are capable of growth at wider range of temperature. Alterations in immune system by disease or antibiotic therapy can upset balance & result in overgrowth, setting stage for opportunistic infection.
What are types of parasites?
• Protozoa
• Helminths (a.k.a. Worms)
• Arthropods
What is Protozoa?
• most are saprophytes but few have adapted to accommodations of human environment & produce variety of diseases, for example Malaria.
Transmission of Protozoa?
host to host through sexual contact or indirectly from
water or food or by arthropod vector.
What are Helminths (a.k.a. Worms)?
• humans can serve as definitive or intermediate
host or as both.
Transmission of Helminths (a.k.a. Worms)?
ingestion of fertilized eggs or penetration of infectious larval stages through skin (Ex. Roundworms, tapeworms, flukes)
What are Arthropods?
• vectors of disease such as ticks, mosquitoes, biting flies, lice, fleas & mites infest external body surfaces & cause localized tissue damage or inflammation secondary to bite or burrowing action of arthropod.
Transmission of Arthropods?
directly by contact with any form of arthropod or its
eggs to human, clothing, bedding or grooming articles.
What is Epidemiology?
study of factors, events, & circumstances that influence transmission of infectious disease in human populations.
Epidemiology focuses on?
• Incidence of disease
• Prevalence of disease
• Source of infection
• Portal of entry
• Site of infection
• Virulence factors
• Signs & symptoms
• Clinical course of disease
The ultimate goal of epidemiologic studies?
Ultimate goal of epidemiologic studies are interruption of spread of infectious disease & its eradication.