Micro3. Chap 20
Terms
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- __________ dieseases are transmitted from one host to another.
- Communicable
- In order for a disease to spread, the pathogen must have a __________ environment in which to live and must leave that environment to be transmitted to susceptible _______.
-
Suitable
Host - The natural habitat of a bug is termed __________.
- Resevoir
- The pathogen leaves animal reservoir through _________ of ________.
- Portal of exit
- Epidemiologists are more concerned with _______ of the disease.
- Rate
- Rate of the disease = ...?
- Percentage of given population that is infected. 100/10,000,000 vs 100/1000
- _________ rate is the number of cases developing in group of people exposed.
-
Attack
10 sick out of 100 = 10% attack rate - _________ rate is the number of cases of illness divided by the population at risk.
- Morbidity
- _________ rate reflects population that dies from the disease.
- Mortality
- __________ reflects number of new cases per specific time period.
- Incidence
- __________ reflects the total number of existing cases.
- Prevalence, a snapshot
- Diseases that are constantly present are termed _________.
- Endemic, this varies with location.
- When endemics are spread worldwide they are termed _________.
- Pandemic
- _________ refers to a cluster of cases in a brief time affecting a specific population.
- Outbreak
- _________ of pathogen affects extent and distribution of disease.
- Reservoirs
- Reservoirs can be...
- Human, non-human or environmental
-
True or False:
Human reservoirs are sometimes not affected by the disease, making it easier to control. - True
- Human reservoirs can be ____________ infections or ____________ carriers.
-
Symptomatic (obvious source of infectious agent)
Asymptomatic (harbors pathogen w/ no ill effects but may shed organisms for long time) - Disease transmitted by non-human animal reservoirs are termed __________, infection into humans is accidental.
- Zoonotic
- Two examples of environmental reservoirs, one in water and one in soil:
-
Water = geardea
Soil = tetunus - Pathogens with ___________ reservoirs are near impossible to eradicate.
- Environmental
- Three types of portals of exit:
-
1. Intestinal tract thru feces
2. Respiratory tract = aerosols (most efficient)
3. Skin = shed with skin cells - Successful pathogens must be able to tranfer from ____________ to susceptible __________.
-
Reservoir
Host - Transmission of pathogen via contact with food, water, living agent is termed ____________ transfer. While the transfer from mother to fetus = _________ transfer.
-
Horizontal
Vertical - ________ contact is when it goes directly from one person to another. Usually bugs that can't survive for extended periods in the environment.
- Direct
- Indirect contact involves transmission via inanimate objects or _________. This is common on cruise ships.
- Fomites
- __________ are the most common vectors.
- Arthropods
- Factors that influence the epidemiology of disease are:
-
1. Dose
2. Incubation period
3. Population characteristics - Probability of contracting a disease is often proportional with ________.
- Dose
- A disease with a _____ incubation period (like smallpox) can spread extensively before first case appears.
- Long
- Six population characteristics that influence occurrence of disease are...
-
1. Immunity to pathogen
2. General health
3. Age (very young or old)
4. Gender
5. Religious and cultural practices (breast feeding, canabalism)
6. Genetic background - Previous exposure or immunization of population __________ susceptibility of population to organism. This can lead to ______ immunity.
-
Decreases
Herd - Stressors such as ___________ or overcrowding increase susceptibility.
- Malnutrition
- Gender influences disease distribution often due to ___________ differences.
- Anatomical
- Epiemiologists investigate disease outbreak to determine __________ agent, __________ and route of ____________. Knowing these things helps minimize spread.
-
Causative
Reservoir
Transmission - _________ studies are used to determine things like person, place and time.
- Descriptive
- The first case of an outbreak is called the ______ ________.
- Index case
- If the infection spread rapidly, probably a _________ _________ epidemic.
- Common source
- A gradual rise in numbers = a _________ disease, termed _________ epidemic.
-
Contagious
Propagated - _________ studies determine which potential factors from descriptive study are relevant.
- Analytical
- ______-________ studies survey range of people to determine prevalence of number of characteristics.
- Cross-Sectional
- ____________ studies are done following a disease outbreak and compare actiosn and events surrounding outbreak.
- Retrospective
- ____________ studies look ahead to see if risk factors from retrospective study predict tendancy to develop disease.
- Prospective
- The only health organization we learned about that doesn't have political ties is the...
- World Health Organization
- ___________ studies are used to judge the cause and effect relationshop of risk factors or prevalence factors and disease development.
- Experimental
- Treatments in experimental studies are compared with __________ and the method of _________-_______ testing is used.
-
Placebo
Double-blind - There is a general upswing of infectious diseases worldwide mainly due to two things:
-
1. Antibiotic resistant strains
2. HIV - __________ infections are defined as hospital acquired infections.
- Nosocomial
- What species is a common cause of nosocomial pneumonia and UTI's and burn infections?
- Pseudomonas species
- _____________ species, E. coli, and other species in the family enterobacteriaceae are part of the normal flora.
- Enterococcus
- ____________ ________ is the biggest threat today. It survives in environment for long time and is easily trasmissable to _________.
-
Staphylococcus aureus
Fomites -
True or False:
All Staph species are pathogenic. - False, most are part of normal flora.
- Health care workers are often the cause of hospital outbreaks due to...
- Improper handwashing or sterile techniques.
- Patient's own normal flora can cause problems if ___________ treatments introduce surface flora to interior regions of body (like the appendix repturing)
- Invasive
- List three ways that infectious agents can be transmitted through a hospital:
-
1. Medical devices (devices usually breach first-line defenses)
2. Healthcare personel
3. Airborne - ________ _________ discovered antibiotics when he was workign with _____________.
-
Alexander Fleming
Staphylococcus - Ernst ________ and Howard ________ successfully purified penicillin, not Fleming.
- Chain and Florey
- Selman _________ isolated ___________ from soil bacterium Streptomyces griseus.
-
Waksman
Streptomycin - Most modern antibiotics come from organisms living in the ______ that are excreating _________ to kill competition.
-
Soil
Toxins - In some cases drugs are chemically altered to impart new characteristics, these are termed:
- Semi-synthetic
- Antimicrobial drugs have ________ toxicity, meaning they cause greater harm to microorganisms then humans, but they arn't totally harmless.
- Selective toxicity
- The toxicity of a drug is termed as its __________ _______. The higher the number is, the less toxic the drug is.
- Therapeutic index
- Drugs can either kill = _________ or inhibit = ___________ bacterial growth.
-
Kill = bacteriocidal
Inhibit = bacteriostatic - ___________ drugs still rely on the host's immunity to eliminate the pathogen.
- Bacteriostatic
- ________ of activity refers to antimicrobials variance when it comes to range of organisms controlled.
- Spectrum
- A narrow spectrum works on either ________ OR _________.
- Gram - OR Gram +
- A broad spectrum works on _________ AND __________. The disadvantage of this one is disruption of normal flora.
- Gram - AND Gram +
- Drugs differ in how they are distributed, metabolized and excreted. The rate of elimination of drug from body is expressed in _______-________.
- Half-life
- Hife life dictates frequency of _______.
- Dosage
- Sometimes drugs are combined. When action of one drug enhances that of another, effect is _________.
- Synergistic (2+2=5)
- When the action of one drug interferes with another, it is termed ___________.
- Antagonistic
- When the effect of combination is neither synergistic or antagonistic, it is called __________.
- Additive (like two narrow spectrum antibiotics)
- One toxic effect from antimicrobial drugs that prevents the boy from making RBC or WBC is called:
- Aplastic Anemia
- Supression of normal flora results in antibiotic associated __________.
- Colitis
- Drugs that interfere with cell wall synthesis have a very _______ theraputic index.
- High, low toxicity with high effectiveness
- Three antimicrobials that deal with inhbition of cell walls are:
-
1. Beta lactam drugs
2. Vancomycin
3. Bacitracin - Penicillins are part of a group of drugs called:
- Beta-Lactams
- Beta-Lactams inhibit ________ __________ formation btwn glycan molecules.
- Peptide bridge
- Vancomycin inhibits formation of _________ chains. This must be given ____________ due to poor absorbtion thru digestional tract.
-
Glycan
Intravenously - ____________ reversibly bins 30S ribosomal subunit and block attachment of tRNA to ribosome.
- Tetracyclins
- Newer tetracylins, like __________, have a longer half life.
- Doxycycline
- ___________ block prokaryotic RNA polymerase, so they block the initiation of transcription. Mostly effective against Gram ___'s.
-
Rifamycins
+ - Rifamycins is generally used to treat _____________ as well as preventing ___________ after exposure.
-
TB
Meningitis - There is resistance against Rifamycin due to mutation coding ______ __________.
- RNA polymerase
- MIC refers to _____________ _____________ ____________. This number is determined through __________ tests.
-
Minimum inhibitory Concentration
Quantitative - MIC is determined by producing _________ __________ with decreasing concentrations of test drug.
- Serial dilutions
- ________-_______ disc diffusion is routinely used to qualitatively determine susceptibility. A clear zone of __________ is shown around effective antimicrobials.
-
Kirby-Bauer
Inhibition