Microbial Interactions with Humans Flashcards
What are the 8 sites known to host a microbiome
- Skin and adjacent mucous membranes
- Upper respiratory tract
- Gastrointestinal tract (including mouth)
- Outer portion of urethra
- External genitalia
- Vagina
- External ear canal
- External eye (lids, conjunctiva)
What are the 6 newly discovered sites that host a microbiome?
- Lungs (lower respiratory tract)
- Bladder (and urine)
- Breast and breast milk
- Amniotic fluid and fetus
- Brain (DNA detected)
- Bloodstream (DNA detected)
What are the sites that only DNA has been detected?
Brain, Bloodstream
What is virulence?
The relative severity of a disease caused by a particular microbe
What are the 5 steps of infection?
- Portal of entry
- Attachment interactions
- Surviving host defense
- Damaging the host/causing disease
- Exiting the host
Describe the Portal of entry step
The route that a microbe takes to enter the tissues of the body to initiate an infection.
: Through mucous membrane, skin, parenteral route
Exogenous - Organisms coming from OUTSIDE the body
Endogenous - Organisms coming from somewhere in the same human
Describe the Attachment interactions step
Use ADHESION which is a process which microbes gain a more stable foothold on host tissues.
Bacterial, fungal and protozoal pathogens attach most often through fimbrae, surface proteins and adhesive slimes or capsules.
Viruses attach by specialized receptors
Explain the surviving host defenses step
Antiphagocytic factors are used by some pathogens to avoid phagocytes (white blood cells)
Some like Streptococcus and Staphylococcus produce leukocidins which are toxic to WBC
OR some microbes secrete a capsule or slime layer to prevent being engulfed
or they can survive within the WBC
What are the 3 ways a microbe can damage their host?
- Directly through the action of enzymes or toxins (both endo and exotoxins)
- Microbial enzymes and exo- endotoxins disrupt host cell structure or connections between host cells. - Indirectly by inducing the hosts defenses to respond excessively or inappropriately
- Epigenetic changes made to host cells by microbe (such as histones, altering the host genes that are expressed)
What are exotoxins and what do they cause?
They’re secreted proteins that are the most potent toxins produced by microbes
Damaging the cell membrane and causing lysis or disrupting intracellular function.
Describe the exiting the host step
Pathogens depart through the portal of exit
What do exoenzymes do?
They break down and inflict damage on tissues, other enzymes dissolve the host’s defense barriers and promote the spread or microbes to deeper tissues.
What are enterotoxins?
Bacterial toxins that affect the GI tract (small intestine)
What are endotoxins
Also lipopolysaccharides (LPS) on gram-negative bacteria, initiates a host inflammatory response cause fever, diarrhea, decreased number of immune cells
What is an infectious dose?
The minimum number of microbes necessary to cause an infection to proceed.
Whats the 7 difference between exotoxins and endotoxins
Exotoxins -
- Proteins from gram + and -, toxic in small amounts
- SPECIFIC mode of action (binds to a specific cell receptors or structures)
- HIGHLY toxic
- Can be converted to a toxoid: FORMALDEHYDE will DESTROY toxicity
- Can be killed by antitoxins
- Does NOT cause Fever
- unstable
Endotoxins -
- LPS only on Gram -, released on cell lysis
- GENERAL/SYSTEMIC : fever, diarrhea, vomiting
- RARELY fatal
- Immune réponse not sufficient to neutralize toxin
- No toxoid potential
- INDUCES fever in host
- stable
What is a toxoid?
a chemically modified toxin from a pathogenic microorganism, which is no longer toxic but is still antigenic and can be used as a vaccine.
What are the 4 cardinal signs of inflammation?
- Redness (blood flow to an area)
- Pain
- Heat (local area, fever)
- Swelling
What is a reservoir?
The primary habitat in the natural world where a pathogen makes its home
What are examples of reservoirs?
Living:
Animals, humans (carriers),
Arthropods
Nonliving: Soil Air Water The built environment
When is a host communicable?
When an infected host can transmit the infectious agent to another host and establish infection in that host.
What does it mean for an agent to be contagious?
Highly communicable , especially through direct contact
What does it mean for an agent to be noncommunicable?
When an infectious disease does not arise through transmission of the infectious agent from host to host.
When a compromised person is invaded by his or her own microbiota (EAR INFECTION). Or when a person gets in contact with a nonliving resivoir.(MYCOSES)
What are the 5 different patterns of transmission?
- Vertical
- Horizontal
- Indirect
- Direct
- Vector/Vehicle
Define Vertical transmission
Transmission is from parent to offspring via the ovum, sperm, placenta, or milk
Define horizontal transmission
Disease is spread through a population from one infected individual to another
Define direct horizontal transmission
Involves very close proximity or actual physical contact between two hosts
Define indirect horizontal transmission
Infectious agent must pass from an infected host to an intermediate conveyor (a VEHICLE which is a nonliving material) from there to another host.
EX: doorknobs, water, air, soil, food
Describe the two vector transmission
Vectors are living
Vehicles are nonliving
Fomite is an inanimate object
Mechanical vector - insect carry microbes to host in its body parts
Biological vector - insects INJECTS microbes into host ; part of microbe life cycle completed in insect . The microbe lives and multiples within the insect.
What is prevalence and Incidence of disease?
Prevalence - total number of existing cases in a given population
Incidence - the number of new cases over a certain time period
What is Ro?
Reproduction rate , how many people will 1 person infect?
The Case fatalility rate is
the number of people who die from the disease, the higher the number the more deadly you know the disease is
Why are reportable disease important?
They help districts etc keep track of the diseases out there
What are some of the reportable diseases?
Anthrax, leprosy, smallpox, syphilllus, TB, Lyme disease, zika virus, yellow fever
An adaptive response in which microorganisms begin to tolerate an amount of drug that would ordinarily be inhibitory is called drug ______.
resistance
Drug resistance arises when ______.
- an organism gains the genetic information for resistance from another organism
- a spontaneous mutation occurs in the organism’s DNA code
Drugs can be identified from noncultivable bacteria by ______.
harvesting antibiotics directly from soil
What are the advantages to the consumption of probiotics?
- They can be helpful for managing food allergies.
- They are safe to consume.
What are the categories of major drug side effects?
- Allergic reactions
- Toxic damage to tissue
- Normal flora disruption
Summarize the problems that have led to the worldwide problem of managing antimicrobial drugs.
increase in superinfections
physicians use a “shotgun” approach to treat minor infections
development of resistance in “bystander” microbes
One consequence of widespread use of ______-spectrum antibiotics is the development of resistance in ______ microbes that are part of the normal biota.
broad ; bystander
The human body typically begins to be colonized by its normal biota _______.
before birth
Resident biota are found in/on the ________.
skin , mouth , nasal passages, large intestine
The effect of “good” microbes against invading microbes is called _______.
microbial antagonism
Microbial hyaluronidase, coagulase, and streptokinase are examples of _______.
exoenzymes
What are the stages of an infection?
Incubation period - the time the initial contact with the infectious agent
Prodromal stage - general symptoms such as fatigue and muscle aches
Acute phase (Height of infection) - marked by fever
Convalescent period - symptoms decline, patients strength and health gradually return
Continuation period - only some infections have this phase. The organisms lingers within the patient or the organism is gone but symptoms continue.
The objective, measurable evidence of disease evaluated by an observer is termed a(n) _______.
sign
The subjective evidence of disease sensed by the patient is termed a(n) _______.
symptom
Long-term or permanent damage to tissues or organs resulting from a specific disease are called _______.
sequelae
Meningitis: deafness
Strep throat : rheumatic heart disease
Lyme disease: arthritis
Polio: paralysis
What is latency?
A dormant state of microbes in certain chronic infectious diseases
A _______ is the presence of small numbers of bacteria in the blood bu not multiplying.
bacteremia
A _______ is an infection indigenous to animals that can, on occasion, be transmitted to humans.
zoonosis
_______ carriers are shedding and transmitting pathogens while they are recovering from an infectious disease.
Convalescent
The study of the frequency and distribution of a disease in a defined population is _______.
epidemiology
The principal government agency responsible for tracking infectious diseases in the United States is the ________.
Centers for Disease Control and Prevention
The number of persons afflicted with an infectious disease is the _______ rate.
morbidity
Ninety people developed diarrhea, fever. and abdominal cramps in the aftermath of a wedding. On diagnosis it was determined that they were suffering from salmonella, and after taking their histories, they all reported that they had eaten the chicken at the reception. This is an example of ________
point-source epidemic
