Exam 2-bacteriology Flashcards
Gram + bacteria
Thick peptidoglycan
Contains Lipoteichoic acid
Gram + staining
- Use crystal violet
- If a bacteria is gram positive the bacteria will stain purple.
- the crystal violet and grams iodine complexes cannot escape a thick peptidoglycan layer
Gram - bacteria
- Thin layer of peptidoglycan
- contains LPS (lipopolysaccharides)
- only ones to have outer membrane which contains LPS
Gram - Staining
- Gram - bacteria will stain pink
- the bacteria pick up the Safrain due to inn peptidoglycan
- Allows for passage of large crystals
Mycobacterium
Contains mycolic acid and LAM (Lipoarabinomaman)
Mycobacteria staining
Acid fast + = pink
Acid fast - = blue (lack of mycolic acid)
-will only work if mycobacterium present
E.coli K88 fimbria
Neonatal pigs
E.coli K99 fimbria
Neonatal calfs
Pili/fimbrae
- Used for adherence
- on bacteria’s surface
- small thread-like
Capsule
- Outer covering, helps to Nevada phagocytes
- polysaccharide of the outside of the cell wall
What is the Capsule used for?
- sticking cells together
- food reserve
- protection against dedication and chemicals
- helps bacteria to evade apoptosis
Endospores
- Survival mechanism for some G+ bacteria
- highly resistant dormant form of bacteria
- produced when bacteria are exposed to adverse conditions or essential nutrients are depleted
Oxygen required
Aerobic
Microaerophilic
Capnophilic
Oxygen Not required or utilized for growth
Obligate anaerobe
Aerotolerant anaerobe
Oxygen not required and not utilized for growth
Facultative anaerobe
How do bacteria cause disease?
Pathogenesis
Triangle of Tragedy-Pathogen
Type Genotype Survival Virulence Route Tropism Dose Resistance Vector
Triangle of Tragedy- Host
Breed Age Sex Genotype Immunity Physiology Damage
Triangle of Tragedy-Enviroment
Housing Space Ventilation hygiene Nutrition Disease control Survival
Microorganism that has the potential to cause disease
Pathogen
The invasion and multiplication of pathogenic microbes in an individual or population
Infection
When the infection causes damage to the individuals vital functions or systems
Disease
Site at which microbes enter our bodies
Port of entry
What are the 4 sites that microbes can enter the body?
1) Skin
2) Mucous membranes of respiratory tract
3) Gastrointestinal tract
4) Urogenital tract
Proteins produced by bacteria and released to outside and they exert action of specific target cells, release when living
Exotoxins
Examples of Exotoxins
Neurotoxins
Leukotoxins
Entertoxins
Heat stable, only released when dead, they can induce inflammation by stimulating the immune system
Endotoxins
Superantigens
- Produced by pathogenic microbes
- (including viruses, mycoplasma, and bacteria)
- Bind to MHC class II molecule –> which binds to T-helper cells (massive cytokines release)
- nausea, vomiting, fever (shock)
Examples of superantigens
Staphylococcus
Streptococcus entertoxins
Smaller circular DNA present in bacteria
Plasmids
Virus particles which attack bacteria
Bacteriophages
The process by which one bacterium transfers genetic material to another through direct contact
Conjugation
The genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surrounding and taken up through the cell membranes (add DNA fragment into DNA)
Transformation
The process by which DNA is transferred from one bacterium to another by a virus
Transduction
Mechanisms by which cause disease
Pathogenesis
Degree of pathogenicity includes severity
Virulence
Properties or traits found in isolates that cause disease but which are not found in isolates of the same species that lack the ability to cause disease
Virulence factors
What predisposes an animal to infectious disease
Predisposition
Sequence of events in bacterial or fungal pathogenesis
1) Entry into the host
2) Evade host defense
3) Colonize the host system
4) Multiply
5) Exert damage in the host
6) Transmit to other hosts - infectious
How bacterial pathogens cause disease?
1) Depleting the host’s nutrients by using them
2) Direct damage to the host cell (toxins)
3) As a result of immune response to the microbe
4) Combination of all
Consequences of Pathogen-host Interaction
-No colonization/ colonization
-Inapparent subclinical/ chronic infection
-Infection, disease followed by recovery
-infection, disease, death, or disability
-Infection, disease, followed by persistence
(Often leading to transmission or carrier stage)
Diagnosis of Bacterial Infections
1) Infection of the agent
2) Identification of the host immune response
Ways to identify the agent in the diagnosis of bacterial infections
- direct detection (microscopic, simple/differential staining, fluorescent antibody staining)
- Isolation and ID
- direct detection of antigens, toxins (ELISA)
- PCR
Ways to identify the host immune response of bacterial infections
1) humoral immune system detect antibodies to an infectious agent (Brucella infection)
2) cell-mediated immune response (TB)
Type of media selective to Salmonella
Hektoen Enteric Agar
Media that is selective for G- bacteria
MacConkey
A media selective for G+ bacteria
Phenylethyl alcohol agar
Aerobic
Bacteria that needs oxygen
Microaerophilic
-needs low amount of oxygen
Capnophilic
Needs CO2 to grow
oxygen not required but can be utilized for growth
Facultative anaerobe
Antigen Detection
-Use antibody reagents. To detect antigens in serum, feces, urine, tissue
Examples of antigen detection
Enzyme immunoassay
Agglutination
Fluorescent antibody staining
Chemical Detection
- Analysis of total cell fatty acids/ proteins
- limited use on clinical specimens
Examples of Chemical detection
HPLC
GLC
MALDI-MS
Biological detection
-Adapted from clotting mechanism of horseshoe crab
Examples of Biological detection
Linulus amoebocyte assay test for LPS
Sterilization Methods
- Moist heat
- Dry heat
- Incineration
- Alcohol flame
Methods used to limit microbial growth
- Fridge
- Boiling
- Pasteurization
- Acidification
Drugs that destroy microbes, prevent their multiplication/growth/prevention their pathogenic effect
Antimicrobials
A low molecular substances produced by a microorganism that at a low concentration inhibits or kills other micro organisms
Antibiotic
Any substance of natural, semi-synthetic, synthetic orgin that kills or inhibits the growth of micro organisms but causes little or no damage to the host
Antimicrobial
** all antibiotics are antimicrobials, but not all antimicrobials are antibiotics
**
Natural Antimicrobials
-produced by bacteria or fungus
Examples of Natural Antimicrobials
- Streptomycin
- Penicillin
- Tetracycline
Semi-synthetic Antimicrobials
-chemically altered natural compound
Examples of Semi-synthetic antimicrobials
- Ampicillin
- Amikacin
Synthetic Antimicrobials
0chemically designed in the lab
Examples of synthetic antimicrobials
- Sulfonamide
- Enrofloxacin
- Macbofloxacin
4 Classification of antimicrobial agents
1) chemical structure
2) mode of action
3) type of antimicrobial activity
4) Spectrum of antimicrobial activity
Prevents degradation of penicillin by B-lactamose
Clavulanic acid
B-lactate antibiotics
Penicillin, Ampicillin, Cephalosporins
An enzyme present in bacteria which can cleave B-lactate ring and inactivate penicillin + contribute to resistance
B-lactamase
Last drugs of choice for some gram+ bacteria
Vancomycin and daptomycin
Examples of Quinolones
- Nalidixic acid
- Ciprofloxacin
- Enrofloxacin
Metronidazole
-makes breaks in the DNA
Inhibits 30s subunit
- Aminoglycosides (bacterial ribosome)
- Tetracyclines (reg ribosomes)
Examples of Aminoglycosides
- Gentamicin
- Amikacin
Examples of Tetracyclines
- Oxytetracycline
- Chlortetracycline
Inhibits 50s subunit
- Macrolides
- Chloramphenicol
- Lincosamides
Examples of Macrolides
- Erythromycin
- Azithromycin
Inhibits RNA polymerase (transcription)
Rifampin
Inhibits tRNA synthetase (translation)
Mupirocin
Folic acid Synthesis Inhibitors
- Sulfonamides
- Trimethoprim
Broad Spectrum antibacterials
Active against both Gram + and Gram - organisms
Examples of Broad Spectrum antibacterials
- Tetracyclines
- Chloramphenicol
- Fluoroquinolones
- Cephalosporins
Narrow spectrum antibacterials
-have limited activity and are primarily only useful against particular specie of microorganisms (G+ and G-)
Examples of Narrow Spectrum antibacterials
- Isoniazid
- Polymyxins
Bactericides Agents
-Kills bacteria and reduces the total # of viable organisms
Bacteriostatic agents
-Arrest the growth and replication of bacteria, thus allowing the host immune system to complete pathogen elimination
