1.1 Flashcards
Microorganisms and the human body (5)
bacteria viruses fungi protozoa helminths (worms)
microbiome (4)
bacteria
viruses
fungi
protozoa
Parasitic organisms
Symbionts that harm or live at the expense of their host
Commensal organisms
Normal microbiota - microbes frequently found on or within
the bodies of healthy persons
Infection
–growth and multiplication of parasite on or within host
Infectious disease
–disease resulting from infection
Pathogen
–any parasitic organism that causes infectious disease
primary (frank) pathogen –
causes disease by direct
interaction with host
opportunistic pathogen –
causes disease only under certain
circumstances
Pathogenicity
–ability of parasite to cause disease
Virulence factor
- any component of a pathogenic microbe that is required for
or that potentiates its ability to cause disease
steps in infectious disease (6)
encounter entry spread multiplication damage outcome
Encounter (3)
Exogenous
Endogenous
Congenital
- Entry (2)
ingress
penetration
Ingress:
inhalation, ingestion
Penetration:
microbes pass through epithelia directly (via
attachment and internalization), insect bites, cuts
and wounds, organ transplants and blood
transfusions
Spread (3)
lateral propagation versus dissemination
anatomical factors
active participation by microbes
Multiplication (2)
environmental factors (e.g. temperature) subversion of host defenses
Mucormycosis (fungal infection) in
rhinocerebral form, almost always with (2)
hyperglycemia and metabolic acidosis
Damage (2)
direct damage
immune response
Outcome (3)
microbe wins, host wins, or they learn to coexist
Normal microbiota-
microbes frequently found on or within
the bodies of healthy persons
commensal organisms
Colonization by bacteria occurs rapidly after
birth
— of bacterial species are part of the normal flora.
Thousands
The Human Microbiome
the collection of all the microorganisms living
in association with the human body
eukaryotes, archaea, bacteria and viruses
Bacteria in an average human body number — times more than human cells
ten
contain a total of about 1000 more genes than are present in the human genome because of their small size bacteria make up only about 1-3% of our body mass
2 to 6 pounds of bacteria in a 200-pound adult
Bacteria in the microbiome of a healthy individual are essential for maintaining —
health
Bacteria in the microbiome of a healthy individual are essential for maintaining health (6)
produce some vitamins that we do not have the genes to make
break down our food to extract nutrients we need to survive
teach our immune systems how to recognize dangerous invaders
produce helpful anti-inflammatory compounds that fight off other disease-causing microbes
occupy space to crowd out disease-causing microbes
detoxification of carcinogens but sometimes are the source of carcinogen production
Changes in the composition of our microbiomes correlate with
numerous disease states
source of infection
manipulation of these communities could be used to treat disease
Locations in body with largest amounts of bacteria (5)
skin (especially moist areas) respiratory tract (nose and oropharynx) digestive tract (mouth and large intestine) urinary tract (anterior parts of urethra) genital system (vagina)
Other body locations have small numbers of bacteria.
Remainder of respiratory and digestive tracts
Some body locations are sterile. (4)
blood, cerebrospinal fluid, synovial fluid, deep tissues
Transient vs. resident organisms
Pathogenicity/virulence also depend on the
host
Definition of pathogen not so certain
periodontitis -
overgrowth of particular bacteria in gingival
crevices
pneumonia -
defenses lowered and microaspirations of
pneumococci
catheter-associated infections -
staphylococci
Oral flora includes (4)
bacteria (and archeae)
fungi
protozoa (eukaryotes)
viruses
~— different species of bacteria are estimated to
be present in the oral cavity
700
Oral habitats (5)
buccal mucosa dorsum of tongue tooth surfaces crevicular epithelium dental appliances
Issues for microbial cells (3)
Nutritional fluxes
Maintaining occupancy
Resistance to damage
anatomical features that create areas that are
difficult to clean (4)
- shape and topography of teeth
e. g. fissures - malalignment of teeth
- poor quality of restorations (e.g. fillings and bridges)
- non-keratinized sulcular epithelium
saliva fxns (7)
mixture of inorganic ions
organic constituents
salivary pellicle
source of food
promotes aggregation of bacteria, facilitating their clearance from mouth
inhibits growth of microbes by non-specific defense factors
maintains pH
saliva organic constituents (2)
proteins
glycoproteins (e.g. mucin)
salivary pellicle
promotes adhesion of bacteria on tooth surfaces
organic components form a coating on tooth surfaces
gingival crevicular fluid (5)
flushing microbes out of crevice source of nutrients for microbes maintains pH specific and non-specific defense factors phagocytosis
phagocytosis
— main phagocyte
neutrophils
microbial factors (4)
competition for adhesion receptors
toxin production
metabolic end products
coaggregation
metabolic end products
negative vs. positive effects
local pH
will vary with diet as a result of
bacterial metabolism
redox potential
a measure of oxygen levels in locality
Factors modulating oral microbial growth (9)
anatomical features that create areas that are difficult to clean saliva GCF microbial factors local pH redox potential antimicrobial therapy diet iatrogenic factors
iatrogenic factors
dental scaling
— are an absolute requirement for
all living organisms
membranes