EXAM 1 Basics of Bacteriology Flashcards
what are two reasons bacterial infections are on the rise?
- advancements in medicine
- created large populations of immunocompromised people
- increasing spread of antibiotic resistant bacteria, facilitated by international travel and the misuse of available antibiotics
what are the oldest, most prevalent forms of life on earth?
bacteria
relationships among bacteria can be surmised by comparing ____
16S rRNA sequences
list and describe the 4 basic shapes of bacteria
- cocci
- spherical
- bacilli
- rods
- short bacilli are called coccobacilli
- spiral forms
- comma-shaped, S-shaped, spiral-shaped
- pleomorphic
- lacking a distinct shape
name 7 key unique features of bacteria
- usually single, circular chromosome
- haploid, no histones
- may have plasmids
- no internal organelles, no nucleus
- cell wall components
- 70S ribosomes
- unique metabolic pathways
- mode of replication (binary fission)
how do bacteria replicate?
binary fission
- DNA replication
- chromosome segregation
- cytokinesis
bacteria are often associated with ___ rather than free swimming
biofilms
what do biofilms promote?
bacterial colonization and persistence
where can biofilms form?
- in the environment
- on medical devices
- on body surfaces
what forms the basis for recognition of bacteria by innate and adaptive immunity and for antibiotic-based therapies?
the unique features of bacteria
what shape do neisseria sp. and moraxella catarrhalis have?
diplococci
what is the shape of streptococci sp?
streptococci
what is the shape of micrococcus luteus?
tetrad
located in soil and on the skin
what is the shape of sacina sp.?
sarcinae
found on skin and in intestines
what is the shape of staphylococcus aureus?
staphylococci
what is the shape of bacillus sp., escherichia sp, mycobacterium sp, salmonella sp, klebsiella sp, pseudomonas sp, yersinia sp, and porphyromonas gingivalis?
single bacillus and diplobacilli
what is the shape of bacillus anthracis and bacillus megaterium?
streptobacilli
what is the shape of haemophilus influenzae, chlamydia trachomatis, and bordetella pertussis (whooping cough)?
coccobacillus
what is the shape of vibrio cholerae?
vibrio
what is the shape of spirillum sp?
spirillum
rat bite fever agent
what is the shape of borellia, brachyspira, and treponemonas, and leptospira sp?
spirochete
lyme disease, relapsing fever, syphilis, leptospirosis
bacteria in biofilms are often refractory to ___ treatments and protected from ___
- antibiotics
- host defenses
bacteria within biofilms can persist for ___, but can break off and do what?
- long periods
- cause systemic or distant infections
biofilm development is often regulated by what?
quorum sensing
describe the gram positive cell wall
thick peptidoglycan layer
contains a plasma membrane
describe the gram negative cell wall
thin peptidoglycan layer with an outer membrane
contains a plasma membrane
which bacteria do not have cell walls?
mycoplasma and ureaplasma sp.
no cell wall, so no peptidoglycan
what is the function of bacterial cell walls?
maintains cell shape, controls influx and efflux of materials, protects against osmotic lysis
bacterial cell walls are the site for what 3 things?
- respiratory chains
- secretion systems
- adhesins
bacterial cell walls are the target of what?
lysozyme and many antibiotics
bacterial cell walls are the basis for ____ pathogens
- serotyping
- using antibodies to distinguish between bacteria
- antigens: O (LPS), K (capsule), H (flagellin)
the bacterial cell wall contains ___ that are recognized by innate and adaptive immune systems
ligands
the gram positive envelope contains ___ and ___ in the peptidoglycan layer
- lipoteichoic acid
- anchors to plasma membrane
- teichoic acid
they anchor the peptidoglycan layer to the plasma membrane
describe the peptidoglycan structure of both gram positive and gram negative cell walls
- binding of peptidoglycan by the pattern recognition receptor (PRR) toll-like receptor 2 (TLR2) can stimulate inflammatory responses
- cleaved by lysozyme
- biosynthesis is inhibited by various antibiotics, including beta-lactams like penicillin
what is contained in the gram negative envelope?
- lipoproteins
- anchor outer membrane to the peptidoglycan layer
- lipopolysaccharides (LPS)
- porins
- O-specific side chains of LPS
- phospho lipid and integral proteins on plasma membrane
what do bacteria that have no cell wall require to stabilize its cell membrane?
- sterols
- cholesterol from host
bacteria that lack a cell wall are linked with what pathogenic conditions?
- pelvic inflammatory disease, pneumoniae, meningitis, abortions, urethritis, infertility, premature birth, and some cancers
how does the unique cell wall of mycoplasma affect the susceptibility of these bacteria to antibiotics?
they will be resistant because they lack a peptidoglycan layer, so the antibiotics don’t have anything to attack
what factors are associated with bacterial cell walls?
- electron transport chains
- aerobic bacteria and facultative anaerobes versus anaerobes
- protein secretion systems
- flagella
- adhesins
- capsules
- spores
what is used by many bacteria to break down glucose to pyruvate, thus creating ATP?
fermentation
what are 4 types of facultative anaerobes, and how do they produce energy?
- phototrophs
- use light to generate energy
- autotrophs
- use chemicals to generate energy
- heterotrophs
- use organic sources
- chemoheterotrophs are the most medically important bacteria
what does superoxide dismutase do?
converts seperoxide to hydrogen peroxide and oxygen
what does catalase or peroxidase do?
converts peroxide to hydrogen and oxygen
describe gram negative secretion systems
- type I, II, and V secretion systems deliver proteins like toxins, siderophores to the extracellular environment
- type III, IV, VI, and VII secretion systems can inject factors (effector proteins or toxins) directly into target host cells
the structure of bacterial flagella promotes what?
bacteria dissemination within host environments, and facilitates chemotaxis towards or away from specific stimuli
highly antigenic (H antigen) and some bacteria can do what to escape immune detection?
swap (phase vary) different flagellin proteins
how can the expression of flagellin be down regulated within a host to avoid triggering innate immune responses?
by stimulating TLR5 or NLRC4
what are axial filaments?
flagella present within the periplasmic space
describe how axial filaments aid in movement
the rotation of the axial filament relative to the cell body causes the entire bacterium (spirochete) to move forward in a corkscrew-like motion, even through material viscous enough to prevent the passage of normally flagellated bacteria
what is the function of bacterial adhesins?
- mediate contact with other bacteria, inanimate surfaces, host cells, and ECM
- associate with different pili and can have unique receptor specificity, thereby affecting tissue tropism
what are anti-adhesins used for?
being developed as anti-bacterial therapeutics
what is the function of type IV pili?
- conjugation (bacterial mating)
- DNA binding/uptake (competence)
- motility
what are capsules?
- layers of polysaccharide (or polypeptide) associated with the bacterial surface
what is the function of capsules?
- provides protection against desiccation, phage, detergents, and antimicrobial peptides
- protects bacteria from phagocytes
antibodies against specific capsule (K antigen) are ___, and for this reason capsular antigens are a main component in some vaccines
opsonic (generate antibodies to recognize specific antigens, which can then be recognized by receptors on macrophages)
