Microbiology and Immunology Flashcards
how are bacterial classified?
their morphological and metabolic/biochemical differences
allows to determine shape or organism, necessary because most bacteria are colorless and invisible to light
staining
most useful microbiological staining technique
gram stain
this type of bacteria stains blue
gram +
this type of bacteria stains red
gram -
different gram stains are a result of differences in what?
cell walls
what type of bacteria cell wall? very thick, contains teichoic acid, doesn’t block diffusion of antibiotics (vulnerable to penicillin and lysozyme), has 2 layers, low lipid content, no endotoxin, no space/porin channel.
gram positive cell wall
thin, cell wall has murrain lipoprotein, 3 layers, high lipid content, has periplasmic space and porin channel, outer cell membrane contains endotoxin (lipid A), blocks diffusion of things that attack walls (penicillins and lysozyme)
gram negative cell wall
are all organisms susceptible to gram staining?
no - require other accomodations
require dark field microscopy, can’t do gram stain
spirochetes
require acid fast staining, can’t do gram stain
mycobacteria
most disease causing organisms are what kind of bacteria?
gram neg rods or gram neg pleomorphic bacteria
do not form spores, non mobile
gram pos cocci
“spreading factor”, needed for invading tissue during spreading infection
hyaluronidase
spherical gram pos cocci, usually arranged in chains or pairs, all are catalase negative, divided into 3 groups based on their ability to homeless red blood cells
streptococcus
completely lyse RBCs, arranged in groups a-u, group a are among the most important human pathogens, many strains are anti-phagocytic, production of hemolysins, ability to adhere to pharyngeal epithelium
beta-hemolytic streptococcus
group A streptococci are causative for?
pyogenic infections, streptococcal pharyngitis, tonsillitis, scarlet fever/rhuematic fever
inflammatory disease that may develop after an infection with streptococcus bacteria can involve heart, joints, brain, skin
rheumatic fever
not bile soluble, most of these are alpha-hemolytic, normal inhabitants of nasopharynx sf gingival crevices, group of streptococcus
viridans group of streptococcus
part of viridans group, bind to teeth by producing dextran polysaccharides in presence of sucrose, not associated with period disease!
S. mutans
metabolize sucrose to lactic acid which creates an acidic environment
s. mutans
used by s. mutants to produce dextran
sucrose
can be digested by S. mutants but the end product is lactic acid
glucose, lactose, fructose
S. intermedius and S. anginosus (normal inhabitants of GI tract) are associated with what?
dental, brain, abdominal abscesses
spherical, gram + bacteria, associated with tongue, colonize in mouth and URT of humans hours after birth
streptococcus salivarius
most common aerobic organisms implicated in facial cellulitis
viridans streptococcus
can be encapsulated with polysaccharide layer, resistant/destructive
streptococcus pneumoniae
generally harmless component of normal flora, penicillin G resistant, non mobile, non spore forming, arranged in grape like clusters, facultative anaerobe, typical for access formation
staphylococcus
most resistant disease causing organism that vancomycin and bactrim are often used 1st to tx
MRSA
major producer of leukocidins, significant exotoxins- coagulase, hyaluronidase (degrades hyaluronic acid - ground substance of subcutaneous tissue), produces pigmented compounds called carotenoids
staphylococcus aureus
bacillus (cause for anthrax and food poisoning)
clostriudum (tetanus, botulism, gangrene, food poisoning, AB resistant pseudo colitis), corynebacterium (diptheria), listeria (endotoxins that cause meningitis and sepsis)
gram pos rods
causes lock jaw or tetanus, spores generally dust born
clostridium tetani
causative organism for meningitis and gonorrhea
neisseria, gram neg cocci
spirochetes (cause for syph**, terponemtosies, lyme disease, leptospirosis), found in associated with NUG/NUP
gram neg spiral shaped organisms
creates an acidic environment “aciduric”, doesn’t produce dextrans but produces a different extra-polysaccharide called lexan, associated with advanced caries in deep enamel
lactobacillus
have been implicated in root caries, role in dental caries initiation and progression is unknown
actinomyces
growth phase of bacteria. growth is slow at 1st as bacteria acclimate to environment, cellular metablic activity noy increased during this phase
lag phase
growth phase of bacteria. phase that microorganisms are most prone to breakdown by antimicrobial agents
logarithmic “eponential” phase
3 enzymes bacteria posses to break down oxygen products
catalase- breaks down hydrogen peroxide
peroxidase- same
superoxide dismutase- breaks down superoxide radical
have all the enzymes, uses kreb’s cycle and glycolysis, examples: neisseria,
obligate aerobes
aerobic, can grow in absence of oxygen by using fermentation, ex: staphylococcus, listeria, actinomyces
facultative anaerobes
“aerotolerant anaerobes”, use fermentation, tolerate low amts of O2, ex: streptococcus, spirochetes, campylobacter (pregnancy gingivitis)
microaerophilic bacteria
hate oxygen, ex: prevotella, porphymonas gingivalis
obligate anaerobes
most often associated with hormonal “pregnancy” gingivitis, facial cellulitis, and NUP/NUG
prevotella
produce collagenase, important pathogen for perio diseases
porphymonas gingivalis
what are most fungi?
obligate aerobes
most common fungus encountered in the dental setting, part of normal flora in digestive/respiratory/urogenital tracts
candidia albicans
energy-less, must have host cell, composed of protein core (capsid) surrounding genetic material, may have outer lipid bilayer (envelope) or may be naked, small (.02-.03 microns)
viruses
refers to the different kinds of organisms a virus can infect
host range
referes to specific kinds of cells a virus can infect and is determined mainly by whether a virus can attach to a cell
specificity
a complete virus particle (including its envelope if it has one)
virion
4 possible outcomes once a host cell has been infected by a virus
death, transformation, latent infection, chronic slow infections
what is the classification of viruses based on?
type and structure of viral nucleic acids (RNA or DNA- never both)
role of _____ is to move the info contained in the DNA to the cell’s cytoplasm where protein synthesis and viral replication takes place
mRNA
primary function of mRNA
translation
transcription is what to what?
DNA to RNA
RNA genome can be similar to mRNA is known as what?
positive strand RNA
RNA genome is a template for production is known as what?
negative strand RNA
examples of RNA viruses?
HIV, Hep A, rhino virus, influenza virus, mumps, measles, rabies
virus that has both positive and negative strands, cannot be translated into proteins until it is transcribed into mRNA
DNA viruses
examples of DNA viruses
HPV, HSV I and II, VZV, CMV, EBV, small pox
spreads via nasopharyngeal secretions, can cross placental barrier, has Koplik’s spots
measles
small, red-based lesions with blue center in mouth, seen in measles
Koplik’s spots
causative organism for herpangina
coxsackie virus
causes chickenpox and shingles upon reactivation of the dormant virus
VZV
DNA hepatitis virus
hep B
RNA hepatitis virus
hep a, c, d, e
hep b vaccine is an example of what type of immunity?
artificial acquired active immunity
gamma globulin is an example of what type of immunity?
passive
protection of body is provided by what 2 systems?
cell mediated immunity and antibody mediated “humoral” immunity
what type of immunity? t-cell, defense against infection (esp mycobacterium tb, viral and fungal), allergic response, graft and tumor rejection, regulation of antibody response
cell mediated immunity
what type of immunity? b cells, defense against infection (opsonizes bacteria, neutralizes toxins, and viruses), allergic response, autoimmunity
antibody mediated “humoral” immunity
what type of immunity? non specific, not acquired from previous antigen exposure, doesn’t improve after exposure, have no memory, includes skin/mucous membranes, natural killer cells, phagocytosis, inflammation, complement proteins
natural immunity
group of proteins that circulate in the blood and serve to assist other defense mechanisms
complement systems
2 complement pathways
classical- antibody dependent
alternative- spontaneous
what type of immunity? occurs after exposure, improves with repeated exposures, mediated by antibodies and t cells, long term memory, passive or active
acquired immunity
cells of immune systems made where
bone marrow
cells of immune systmes
leukocytes- granulocytes, lymphocytes, monocytes, dendritic cells
types of t cells
t-cytoxic cells, helper cells “CD4 cell”
only T cels that can directly attack and kill diseased cells, including cancer cells
cytoxic t cells
produce cytokines that stimulate macrophages, NK cells, dendritic cells, and other t cells
t helper cells
what type of cell? differentiate into plasma cells and produce antibodies, antigen presenting cells, can form memory cells, involved in humoral immune response
b cells
what do plasma cells come from?
antibodies
functions of this cell- phagocytosis, antigen transportation/processing/presentation, cytokine production
macrophages
kill virus and tumor infected cells, active w/ out prior exposure to antigen, non specific, a lymphocyte, kill with out antibody
Natural killer (NK) cells
most numerous WBC, capable of phagocytosis, migrate in response to chemotactic factors (diapedesis), 1st line of defense
Polymorphonuclear neutrophils (PMNs)
key regulator of the immune system, antigen presenting cell capable of activating T and B cells
dendritic cells
immunoglobulins that react specifically with antigen, 5 classes- IgG, IgM, IgA, IgD, IgE
antibodies
immunoglobulin class, predominant in secondary response, opsonizes, capable of activating the classical (antibody) complement pathway
IgG
immunoglobulin class, produced in primary response, most efficient in agglutination “clumping”, 10 binding sites, largest antibody, capable of activating the classical “antibody” complement pathway
IgM
immunoglobulin class, main immunoglobulin in secretions, has J chain and secretory component, prevents attachment of antigen to mucous membranes
IgA
immunoglobulin class, no known function in body, present in small amounts in serum
IgD
immunoglobulin class, mediates anaphylactic hypersensitivity by binding to mast cells and basophils, targets certain parasites
IgE
hypersensitivity reaction- IgE antibody is induced by antigen “allergen”, binds to mast cells and basophils, release of mediators such as histamine, requires previous exposure to allergen
Type I- anaphylactic (immediate)
what cells release histamine?
mast cells
pallor is or is not a sign of histamine release?
is not
hypersensitivity reaction- antigens on a cell surface combine with antibody leads to complement mediated lysis, ex: Rh and transfusion reactions, primary antibody- IgG
Type II- cytotoxic
hypersensitivity reaction- release of lysosomal enzymes cause tissue destruction, complement is activated, PMNs called in, IgG primary antibody
Type III- Immune Complex
hypersensitivity reaction- helped T cells are sensitized by antigens, *cell versus antibody mediated, induces inflammation and activation of macrophages which release mediators, ex: Tb skin test
Type Iv- delayed
autoimmune diseases more common in male or female?
female
autoimmune disorder, associated with Raynaud’s phenomenon and generalized widening of the periodontal ligament space
scleroderma
what makes up protein?
amino acids
smallest unit of protein
amino acids
buffer in saliva
sodium bicarbonate
primary cell in the PDL
fibroblasts
movement of cells to the site of inflammation
chemotaxis
