Exam 3 material Flashcards
human microbiome
sum total of all microbes found on and in normal humans
critically important to the health and functioning of its host organisms
infection
microbes get past host defenses, enter tissues, and multiply
disease
deviation from health that results when cumulative effects of infection damage or disrupt tissues and organs
infectious disease
a pathologic state caused directly by miroorganisms or their products
what is the human microbiome project?
worldwide research efforts to characterize microbes living on human bodies when healthy
determine how the microbiome differs on various diseases
utilizes powerful techniques of genome sequencing and big data tools
how many protein-encoding genes are there in human cells
21,000
are microbes found in sterile environments?
yes
how many viruses are found in human feces
100 million
what sites typically harbor normal microbiota
skin and adjacent mucuos membranes, upper respiratory tract, gastrointestinal tract, outer portion of urethra, external genitalia, vagina, external ear canal, external eye
what factors weaken host defenses and increase susceptibility to infection
old age and extreme youth(infancy and prematurity)
genetic defects in immunity and acquired defects in immunity
surgery and organ transplants
underlying disease: cancer, liver malfunction, diabetes
chemotherapy/immunosuppressive drugs
physical and mental stress
pregnancy
other infections
where do newborns get important microbiota
through its trip through the vagina
-lactobacillus provides the baby with the necessary enzymes to digest milk\
what are some disorders attributed to disruption of gut microbiome
inflammatory bowel disease, obesity
inflammatory bowel disease
chronic inflammation of the gut and disruption of homeostasis, an impaired microbiome(dysbiosis)
ulcers or sores form on superficial lining of large intestine and rectum
also called Crohn’s disease
dysbiosis
when normal colon microbiome is impaired, not in homeostasis
ex: clostridioides difficile infection(CDI)
strict anaerobic, gram-positive
antibiotic-associated colitis
primary result of antibioitic treatment for some other infection and ingestion of spores
antibiotics can drastically affect normal microbiome of colon
C.diff is allowed to proliferate, releasing toxins that attack the mucosa of the colon, causing epithelial necrosis in the colon
pseudomembranous colitis
inflammatory cells, dead cells, necrotic tissue, and fibrin that obstructs the intestine
cramping, water diarrhea, can result in death
microbiological factors affecting C.difficle infection and recurrence
microbiota(healthy microbiota inhibits to C.difficle spore colonization, but once microbiota populations are disrupted C.diff infection can occur)
c. difficle spore variability(disrupted microbiota will not lead to CDI unless spores are present in gut)
fecal microbial transplants
treatment: very potent drugs, relapse occurs
fecal transplant
combat bacterial infection of colon by infusing the colon with feces from a healthy person to displace the pathogenic c. difficle, restoring the normal balance in the colon
reservoirs for c. difficle
likely that colonized patients serve as reservoirs for c. difficle in health care settings
domestic animals(cattle, horses, dogs, cats, etc)
food supply(meat)
pathogen
a microbe whose relationship with its host is parasitic and results in infection and disease
pathogenicity
an organism’s potential to cause disease
true pathogens(primary pathogens)
capable of causing disease in healthy persons with normal immune defenses
have well developed virulence properties
generally associated with specific disease
opportunistic pathogens
cause disease when the host’s defenses are compromised or when the pathogens become established in a part of the body that is not natural to them
not pathogenic to normal, healthy people
virulence
relative severity of a disease caused by a particular microbe
degree of pathogenicity
what is the virulence of a microbe determined by
its ability to establish itself in a host
enter host, attach firmly to host tissues, negotiate the microbiome, and survive host defenses
cause damage
produce toxins that damage host tissues or induce a host response that actually harms or damages the host tissues or cells
virulence factor
any characteristic or structure of the microbe that contributes to its ability to establish itself in the host and cause disease
what does influenza(viral infection) frequently lead to
pneumonia(often a bacterial infection)
what tracts are involved in finding a portal of entry
skin, GI tract, respiratory tract, urogenital tract, endogenous biota
what parts are involved in attaching firmly and negotiating the microbiome
fimbrae, capsules, surface proteins, and viral spikes
what parts are involved in surviving host defenses
avoiding phagocytosis, avoiding death inside phagocyte, absence of specific immunity
what parts are involved in the portal of exits
respiratory tract, salivary glands, skin cells, fecal matter, urogenital tract, blood
portal of entry
route that a microbe takes to enter the tissues of the body to initiate an infection
exogenous
microbe originating from a source outside the body from the environment or another person or animal
endogenous
microbe already existing on or in the body-normal biota or a previously silent infection
what does mycobacterium tuberculosis travel through
both the respiratory and gastrointestinal tract
what do streptococcus and staphylococcus enter through
through the skin, urogenital tract, and the respiratory tract
infectious dose
minimum number of microbes necessary to cause an infection to proceed
phagocytes
cells that engluf and destroy host pathogens by means of enzymes and antimicrobial chemicals
antiphagocytic factors
virulence factors used by some pathogens to avoid phagocytosis by phagocytes
leukocidins
cytotoxin that kill phagocytes outright
produced by streptococcus and staphylococcus
exoenzymes
enzymes secreted by microbes that break down and inflict damage on tissues
dissolve the host’s defense barriers to promote the spread of disease to other tissues
mucinase
digests the protective coating on mucous membranes
major factor in amoebic dysentery
hyaluronidase
digests the ground substance that cements animal cells together
coagulase
causes clotting of blood or plasma
kinase
dissolves fibrin clots
toxins
a specific chemical product of microbes that is poisonous to other organisms
neurotoxins
act on nervous system
enterotoxins
act on intestine
hemotoxin
lyse red blood cells
nephrotoxins
damage the kidneys
sign
objective evidence of disease as noted by an observer
symptom
subjective evidence of disease as sensed by the patient
syndrome
a disease identified by a certain complex of signs and symptoms
signs of inflammation
edema(swelling), granulomas and abscesses, lymphadenitis
edema
the accumulation of fluid in afflicted tissue
granulomas and abscesses
walled-off collections of inflammatory cells and microbes in the tissues
lymphadenitis
swollen lymph nodes
symptoms of inflammation
fever, pain, soreness, swelling
signs of infection in the blood
septicemia
septicemia
a general state in which microorganisms are multiplying in the blood and are present in large numbers
why do infections go unnoticed
no noticeable symptoms are produced
microbe is active in host tissues
host does not seek medical attention
asymptomatic
what are the major portals of exit
coughing/sneezing, insect bite, removal of blood, feces, urine, skin cells and lesions
incubation period
time from initial contact with the infectious agent to the appearance of symptoms
agent is multiplying but has not caused enough damage to elicit symptoms
prodromal stage
1-2 day period when the earliest notable symptoms of infections appear
vague feelings of discomfort: head and muscle aches, fatigue, upset stomach, general malaise
acute stage
infectious agent multiplying at high levels, exhibits its greatest virulence, becomes well established in its target tissue
convalescent period
patient begins to respond to infection and symptoms decline
patients health and strength gradually return due to healing nature of immune response
reservoir
primary habitat in natural world from which a pathogen originates
transmitter
individual of object from which an infection is acquired
syphilis
reservoir and transmitter are the same
carrier
an individual who inconspicuously shelters a pathogen, spreads it to others without any notice
what is the typical reservoir of animals
arthropods such as fleas, mosquitoes, flies, and ticks
larger animals:mammals=rabies, birds=psittacosis, lizards=salmonellosis
zoonosis
an infection indigenous to animals but naturally transmissible to humans
close association between animals and humans
communicable
a disease in which an infected host can transmit the infectious agent to another host and establish infection in the host
contagious
disease that is highly communicable, especially through direct contact
influenza and measles are highly contagious
noncommunicable
infectious disease that does not arise through transmission of the infectious agent from host to host
vertical transmission
disease transmitted from parent to offspring via ovum, sperm, placenta, milk
horizontal transmission
disease is spread through a population from one infected individual to another
direct contact
close contact between people
indirect transmission
an object or substance carriers the agent from one person to another
fomite
inanimate object
vehicle
natural, nonliving material like air, water, soil, and food
vector transmission
arthropods that harbor an infectious agent and transfer it to a human
mechanical vector
insect carries microbes to host on its body parts
biological vector
insect injects microbes into a host; part of microbe life cycle completed in insect
nosocomial infections
infectious diseases acquired or developed during a hospital or health care facility stay
what are the factors tied to healthcare-associated infections
compromised patients
collection point for pathogens
lowered defenses permit normal biota to enter the body
infections acquired directly or indirectly from fomites, medical equipment, other patients, medical personnel, visitors, air, and water
what are the most common healthcare-associated infections
pneumonia
gastrointestinal illness
urinary tract infections
bloodstream infections
surgical site infections
common hospital pathogens
clostridioides difficle
staphylococcus aureus
etiologic/causative agent
cause of infection and disease
koch’s postulates
series of proofs that became the standard for determining causation of infectious disease
obligate intracellular parasites
cannot multiply unless they invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses
properties of viruses
obligate intracellular parasites
ubiquitous in nature and had major impact on development of biological life
ultramicroscopic in size
capsid
protein shell that surrounds the nucleic acid
nucleocapsid
the capsid together with the nucleic acid
naked viruses
only have a nucleocapsid
envelope
external covering of a capsid, usually a modified piece of the host’s cell membrane