Micro Exam 4- Quiz & Chapter 14 Flashcards
Which of the following is not a most common portal of entry for pathogen?
skin
The LD50 is a
a measure of potency of a toxin
Siderophores compete with the host’s
iron-transport proteins
lymphocytes produce intense immune response by producing
cytokines
All of the following organisms produce exotoxins EXCEPT
E. coli
Contributing factor of Pathogenicity of an organism to host cells is best defined by?
numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production
Endotoxins are tested by
LAL test
The rise of herd immunity amongst a population can be directly attributed to
Vaccinations
Transient microbiota differs from normal microbiota in which transient microbiota
are present for a relatively short time
The science that deals with when diseases occur and how they transmitted is called
Epidemiology
A disease in which causative agent remains inactive for a time before producing symptoms is referred as
latent
In which of the following patterns of disease does the patient experience no signs or symptoms?
both incubation and convalescence
Which of the following is NOT a zoonosis?
influenza
Normal microbiota that compete with pathogens or alter the environment and this is phenomenon is known as Competitive Exclusion
True
Ergot and aflatoxins are toxins produced by gram negative bacteria
False
Biofilms provide pathogens with an adhesion mechanism and make them susceptible to antimicrobial agents.
False
Adaptive immunity is induced resistance to a specific pathogen and is achieved by
Lymphocytes
Study of reactions between antibodies and antigens is known as
Serology
Which of the following statements about M protein is FALSE?
It is readily digested by phagocytes.
Presence of toxin without microbial growth is known as intoxications
True
What is pathology?
Scientific study of disease
(pathos= suffering)
(logos= science)
etiology
Cause of the disease
infection
Invasion or colonization of the body by the pathogens
disease
Occurs when an infection results in any change from a state of health
An infection may exist in the absence of detectable disease
TRUE
Normal microbiota:
Microorganisms that establish permanent residence (colonize) but that do not produce disease under normal conditions
ei; bodys normal flora like E. coli in the intestines
Transient microbiota:
May present for several days, weeks, or months and then disappear
Ei; Skin flora example Staph
Influencing factors that determine the distribution and composition of normal microbiota:
Nutrients: May be derived from dead cells, food in the GI tract, secretory and excretory products of cells, and substances in body fluids
Physical and chemical factors: Temperature, pH, O2 & CO2, salinity, and sunlight
The host defenses: Variety of molecules and activated cells that kill microbes, inhibit growth, prevent their adhesion to host cell surfaces, and neutralize toxins
Mechanical factors: Chewing, flow of saliva, digestive secretions, muscular movement and flushing action of urine
Other factors that effect normal microbiota
Age Nutritional status Diet Health status & disability Hospitalization Stress Climate & geography Personal hygiene, living conditions Occupation and lifestyle
Once established, the normal microbiota can benefit the host by preventing the overgrowth of harmful microorganisms this phenomenon is called
Microbial antagonism or competitive exclusion
Example: Eg: E.coli cells in large intestines produce bacteriocins, proteins that inhibit the growth of other bacteria of the same or closely related species such as pathogenic salmonella and shigella
Symbiosis:
A relationship between normal microbiota and host cells. A relationship between two organisms in which at least one organism is dependent on the other
Commensalism:
A symbiotic relationship in which one of the organisms benefits and the other is unaffected
Eg: Staphylococcus epidermidis
Mutualism:
A symbiotic relationship that benefits both organisms
Ex. Beneficial microorganisms may be able to transfer antibiotic-resistance genes to pathogens
Parasitism:
One organism benefits by deriving nutrients at the expense of the other. Many disease-causing bacteria are parasites
Opportunistic microorganisms
They don’t cause disease in their normal habitat but do in a different environment
Ex. E. coli, Generally harmless if it remains in large intestines
But they may cause urinary tract infection (urinary bladder), pulmonary infections (lungs), meningitis (spinal cord), or abscesses (wounds)
Syndrome:
A specific group of symptoms or signs that accompany a particular disease
Communicable disease:
Infected person transmits infectious agent either directly or indirectly
Ex: chickenpox, measles, influenza, genital herpes, typhoid fever, and tuberculosis
(Contagious diseases: Spreads rapidly)
Noncommunicable disease:
Not spread from one host to another. These diseases are caused by microorganisms that reside inside the body or when they enter the body
Example is Tetanus; produces disease only when it is introduced to the body via wounds/abrasions
Occurrence of a disease
Incidence:
of a disease is number of people in a population who develop a disease during a particular period
(Indicator of spread of disease)
Ex: Incidence of COVID 19 in USA during March 2022
Prevalence of a disease is
the number of people in a population who develop a disease at a specified time, regardless of when it first appeared
Ex. Prevalence of COVID 19 in USA
Prevalence and incidence among specific groups of people, regions
Sporadic disease occurs
only occasionally example: Typhoid fever
Endemic disease- A disease constantly present in a population (cold)
A disease constantly present in a population
Ex. (cold)
Epidemic-
If many people in a region acquire a certain disease in a relatively short period, it is called an epidemic disease
Ex. (influenza)
Pandemic-
An epidemic disease that occurs worldwide is called a pandemic
Ex. (Covid-19)
Severity or duration of a disease
Acute:
Develops rapidly but lasts only a short time (Influenza)
Chronic:
Develops slowly but lasts for more time (Hep-B)
Subacute:
Intermediate between acute and chronic (Tuberculosis)
Latent disease:
In which causative agent remains inactive for a time (herpes)
Immunity-
- Protection against disease
Vaccination-
Provides immunity to a particular disease
Herd immunity-
When many immune people are present in a community (vaccinations)
Extent of host environment
Local infection:
Invading organisms limited to a relatively small area of the body (boils and abscesses)
Systemic infection:
Microorganisms or their products are spread throughout the body by blood or lymph
Focal infection:
Specific Areas of the body
Sepsis:
A toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins
Septicemia:
Blood poisoning arising from multiplication of pathogens in the blood (Bacteremia, Toxemia, Viremia)
Stages of a Disease
People can serve as reservoirs of disease during this entire period
- Incubation period
Interval between the initial infection and the 1st appearance of any signs of symptoms
Incubation period depends on specific microorganism involved, its virulence/degree of pathogenicity
No. of infecting microorganisms, and the resistance of the host
- Prodromal period
Short period that follows the period of incubation in some diseases
Characterized by early, mild symptoms of disease such as general aches and malaise
- Period of illness
Disease is most severe with overt exhibition of symptoms
Patients’ immune response and other defense mechanisms overcome the pathogen
Survival or death of patient occurs
- Period of decline
Signs and symptoms subside
May take 24 h or several days
Patient is vulnerable to secondary infections
- Period of convalescence
– Recovery of body to predeceased state
Covid 19 Illness Course
Spread of infection
I) Human reservoirs
Act as carriers and transmit the disease (symptomatic and asymptomatic)
II) Animal reservoirs
Both wild and domestic animals are living reservoirs of microorganisms
Diseases that transmit through animals are called zoonoses
Eg: Rabies found in bats, skunks, foxes, dogs, and coyotes
Lume disease found in mice
Transmission occur via direct contact with animals, animal wastes, contamination of food, water and air; consuming infected animal products or by insect vectors
III) Nonliving reservoirs
Soil and water
Transmission of disease via 3 principal routes
Contact transmission-
Direct contact transmission- Person to person transmission
( Eg: common cold, influenza, staphylococcal infections, Hep-A, STDs )
Indirect contact transmission- Transmission from fomites such as (tissues, towels, utensils, etc.. )
Droplet transmission- Through droplets in the air by (coughing, sneezing, laughing, or talking and travel less than 1m from the reservoir to the host)
- One sneeze may produce 20,000 droplets
- Disease agents that travel short distances are not considered airborne
ii) Vehicle transmission
Waterborne, foodborne, airborne
iii) Vectors :
Insects and Arthropods act as carriers
Mechanical transmission:
Passive transport of the pathogens from insect’s feet or other body parts
Biological transmission:
Active process and more complex. Arthopod or insect bites and ingest some of the infected blood into the host. The pathogens then reproduce and increase in the number inside the host
Epidemiology (epi “on or upon”; demos “people” ; logos “the study of”)
The scientific study of when and where diseases occur and how they are transmitted in populations is called epidemiology
It takes into account of factors such as :
Transmission
Incidence
Frequency
Chain of Infection
Father of Epidemiology
John Snow (1813-1858),
The story of Broad Street Pump
Cholera in London, 1854
Epidemiologists
Detectives and reporters
5Ws: What, Who, Where, When, Why & how
Descriptive epidemiology
Studies patterns by collecting data relating to person, place, time
Influenza in the winter, West Nile Virus in the summer
Lyme disease in NE USA & Dengue fever in Central and South America
Pneumocystis pneumonia is seen only in immunocompromised individuals
Analytical epidemiology
Takes the descriptive epidemiology data and formulate hypotheses about the cause of the disease and possible risk factors involved
Experimental study: Two groups of patients to compare a new vaccine
Observational study: Observe the disease status of each study participant
