Microbiology - Block 2 - Part 1

cipoxixo's version from 2017-01-21 14:50


Question Answer
Molecule in the cell wall of bacteria that is the target of beta-lactam drugsPeptidoglycan
Sometimes used as sites of attachmentPilus/Finbria
Bacteria that absorbs Gram stainGram Positive
Bacteria that do not absorbs Gram stainGram Negative
Bacteria that has a thick cell wall containing large amounts of peptidoglycan along with Teichoic acid and Lipoteichoic acidGram Positive
Bacteria that has a thin cell wall containing peptidoglycan and an outer membrane composed of Lipopolysaccharide (LPS)Gram Negative
Outer membrane of Gram negativeLipopolysaccharide (LPS)
Holes in the Lipopolysaccharide that allow substances to reach the bacteria cell wallsPorins
Lipopolysaccharide (LPS) is also known asEndotoxin
The toxic component of Lipopolysaccharide (LPS)Lipid A
This antibiotic cannot pass through the porins of Gram negative bacteria to target the peptidoglycan and is therefore not a viable treatment antibiotic for Gram negative bacteriaVancomycin
Bacteria that are Gram positiveThick Cell Wall
Bacteria that are Gram negativeThin Cell Wall
The structure of peptidoglycan is composed of these glycan subunitsn-Acetylmuramic Acid (NAM) and n-Acetylglucosamine (NAG)
The peptide sequence that is targeted by vancomycinD-Alanine - D-Alanine
Transpeptidase-carboxypeptidase enzymes are also known asPenicillin-Binding Proteins
Formation of these help certain bacteria survive harsh conditions and are highly resistant to dessication, chemicals, hot/cold tempsEndospores
The two important genera of bacteria that form sporesBacillus and Clostridium
Beta-lactum drugs work best at this phase of bacterial growthLog Phase
2O2- + 2H+ > H2O2 + O2Superoxide Dismutase
2H2O2 > 2H2O + O2Catalase
O2 necessary, use only aerobic respiration and die in absence of O2Obligate aerobes
Pseudomonas, Mycobacterium are examples ofObligate aerobes
Require lesser amounts of O2 - 5 to 10%Microaerophiles
Campylobacter, Helicobacter are examples ofMicroaerophiles
Can use both aerobic respiration (using O2) and fermentation/anaerobic respiration (without O2)Facultative anaerobes
Enterobacteriaceae is an example ofFacultative anaerobes
Cannot use O2 and will die when exposed to O2Obligate anaerobes
Clostridium, Bacteroides are examples ofObligate anaerobes
Bacteria that live outside of a cellExtracellular bacteria
Vibrio cholera is an example of this life styleExtracellular bacteria
Can survive both outside or inside host cells. Intracellular bacteria escape antibodies (present in extracellular environment), can only be eliminated by a cellular immune response. Have adapted mechanisms to escape host killing mechanisms once internalizedFacultative intracellular bacteria
Grows inside macrophages, induces its’ own uptake & blocks lysosomal fusionLegionella
Grows inside macrophages, destroys phagosome, inhibits lysosomal fusion, escapes and grows in cytoplasm of macrophageMycobacterium tuberculosis
Cannot survive outside host cellsObligate intracellular bacteria
Chlamydia is an example of this type of bacteria life styleObligate intracellular bacteria

Gram Stain and Morphology

Question Answer
The genus of bacteria and the type of antibiotic to be used is indicated byGram Stain
Gram +, Cocci, chainStreptococcus
Gram +,Cocci, clusterStaphylococcus
Gram +, Cocci, pairsStreptococcus pneumoniae
Gram -, Cocci, pairsNeisseria
Gram +, Bacilli, chainBacllus anthracis
Gram +, Bacilli, with terminal sporesClostridium tetani
Gram -, Vibrio, isolated with flagellumVibrio cholera
Gram -, Coccobacilli, isolated/pairsBordetella pertussis
Gram +, Coccobaclli, pairsCorynebacterium diptheriae
Gram -, Spiral, isolatedHelicobacter pylori
Gram +, Bacilli, isolatedClostridium Botulinum
Gram o , Coccobaclli, pairsKlebsiella pneumoniae

Bacteria Genetics

Question Answer
Genes directing transfer of plasmid to other cellsFertility plasmid
Genes for antibiotic resistanceResistance plasmids
Genes for toxin productionExotoxin Plasmids
Plasmids that can integrate into bacterial chromosomeEpisomes
Genes the can copy themselves and then excise themselves from the chromosome leaving a copy where they were and insert into another part of the chromosome or into a plasmidTransposons
The genes that encode many virulence factors are clustered together. Examples include genes encoding adhesins, invasins, and exotoxins are adjacent to one anotherPathogenicity Islands
The process by which bacteria transfer genes from one cell to another by cell-to-cell contactConjugation
There is one-way transfer of DNA from a donor (or male) cell to a recipient (or female) cell throughSex Pilus
The sex pilus forms this between the two bacteriaConjugation Bridge
Many conjugative plasmids carry genes for thisAntibiotic Resistance
The transferred F plasmid integrates into the chromosomeHigh-frequency Recombinant (Hfr Cell)
Controls conjugationFertility factor (F plasmid)
Transfer of genes from one cell to another via phage-vector, no cell-to-cell contact occursTransduction
A phage picks up bacterial DNA by error and transfers the DNA into another bacteriaTransduction
Only undergo lytic replicationVirulent Phages
Can undergo both types of replicationTemperate Phages
Uptake of naked DNA from the environment by competent cellsTransformation

Bacteria Pathogenessis

Question Answer
A microorganism capable of causing diseasePathogen
One that rarely causes disease in an immunocompotent host but can cause serious infection in immunocompromised individualsOpportunistic Pathogen
Is the ability of a microorganism to cause diseasePathogenicity
One that lives in a certain niche in the host and is unharmful there. May be pathogenic when introduced into other areas of the bodyCommensal
Is a quantitative measure of pathogenicityVirulence
Attributes possessed by disease-causing microorganisms that aid in their colonization of host tissue and establishment of infectionVirulence Factors
Entry into host tissue, Adherence to host cells, Evasion of primary host defenses, Growth in numbers are in this stage of infectionColonization
Invasion accompanied by inflammation and production of toxins, enzymes – damage host tissue are in this stage of infectionProduction of Disease
Prevents bacteria from being carried away by mucus or washed swept away by fluids using pili/fimbriae in this stage of infectionAdherence to Host Surfaces
Capsules and IgA proteases, biofilm production, intracellular survival of bacteria, antigenic variation and inactivation of complement are measures used by bacteria in this stage of infectionEvasion of Primary Host Defenses
Variable expression of antigens that constantly change the presentation of the bacteria to the immune systemAntigenic Variation
Neisseria meningititis, Haemophilus influenzae type b, Streptococcus pneumoniaeall are encapsulated and produce IgA proteases which can cause this if it can get into the CSFMeningitis
Cells of immune system and antibiotics cannot penetrate this structure produced my a group of bacteriaBiofilm
Secreted into the surrounding environmentExotoxin
Polypeptides, antigenic, can be converted to toxoids, A-B subunit toxinsExtoxin
An integral part of the cell wall of only Gram negative bacteriaEndotoxin
Structural part of cell wall (outer membrane). Found only in Gram negative bacteria and released into host circulation following bacterial cell lysisEndotoxin
Subjecting exotoxins to low heat and chemicals (eg. Formaldehyde) in the laboratory environment inactivates them. Looses toxicity but retains antigenicityToxoid
Dimeric endotoxin structureA-B Subunit Exotoxin
Subunit that binds the exotoxin to specific receptors on target cellsB Subunit
Subunit that enters the host cell and exerts toxic effectA Subunit
A-B subunit toxin that inhibits protein synthesis by binding to EF-2Diphtheria Toxin
A-B subunit toxin that activates cAMPCholera Toxin
Cholera toxin increases cAMP by binding toAdenylate Cyclase
Toxin that inhibits of protein synthesis by ADP-ribosylation of host elongation factor (EF-2). Primarily targets heart/nerves/epitheliumDiphtheria Toxin
Toxin inhibition of protein synthesis by ADP-ribosylation of elongation factor (EF-2). Primary target is the liverPseudomonas Exotoxin A
Inhibits protein synthesis by interfering with 60S ribosomal subunitShiga and Shiga-like Toxin
Stimulates adenylate cyclase by ADP-ribosylation of GTP binding protein. Hypersecretion of fluids and electtrolytes from intestinal epitthelium. Profuse watery diarrheaCholera Toxin
Stimulates adenylate cyclase by ADP-ribosylation of GTP binding protein. Watery diarrhea.Heat Labile Toxin (LT)
Stimulates guanylate cyclase. Watery diarrheaStable toxin (ST)
Heat labile toxin (LT) and Stable toxin (ST) are produced byEnterotoxigenic E.coli
ADP ribosylation of Gi (inhibitory G protein - negative regulator of adenylate cyclase) causing increased cAMPPertussis Toxin
EF = edema factor = adenylate cyclase, LF = lethal factor, PA = protective antigen. Decreases phagocytosis; causes edema, kills cellsAnthrax Toxin
Toxin causes cell membrane damage and leakage of cell membraneCytolysins
Has lecithinase activity which damages cell membranesAlpha Toxin (Clostridium perfringens, Myonecrosis “gas gangrene”)
Inserts into membrane to form pores which causes cell membrane to become leakyAlpha Toxin (Staph aureus)
Toxins that inhibit normal neuron function or transmissionNeurotoxin
Blocks release of inhibitory neurotransmitters glycine & gamma-amino butyric acid (GABA). Inhibits neurotransmission in inhibitory synapses. Results in muscle spasms, spastic paralysisTetanus Toxin
Blocks release of acetylcholine from peripheral cholinergic neurons. Results in flaccid paralysisBotulinum Toxin
Cause non-specific activation of T-helper lymphocytes. Bind and link MHC-II molecule (of antigen-presenting cell) with T-cell receptor (on T-helper cell) outside of the peptide binding groove. Large numbers of T cells are activated irrespective of their specificity for the antigen which leads to massive amount of cytokines secretedSuperantigens
Pyrogenic, Fever, rash, shock, capillary leakage. Endotoxin enhancer which increases susceptibility to LPSToxic Shock Syndrome Toxin (TSST-1)
Toxic shock syndrome toxin is produced byStaph aureus
Pyrogenic, Fever, rash, shock, capillary leakage. Endotoxin enhancer which increases susceptibility to LPS, CardiotoxicityErythrogenic/Pyrogenic Toxin
Erythrogenic/pyrogenic toxin is produced byStrep pyogenes
Inject the exotoxins they produce directly into host target cells using this system. Toxin evade the antibodies because it directly enters a host cellType III Secretion System