August MGI Final Exam

2.1

Growth dependent

requires growth in diagnostic media which can take days, provides identification/treatment options

Growth independent

performed directly on specimens, detect pathogens by molecular recognition (using DNA/DNA base pairing or antibody/antigen rxns)

Serotypes

defining different strains of the same pathogen using its antigens

Enzyme immunoessays (growth independent)

enzymes can be chemically attached to antibodies (produce color that can be measured)

PCR (growth independant)

answers does a patient sample contain DNA of a specific pathogen (product is made only if primers exactly base pair with pathogen DNA from patient)

3.2

Selective toxicity

kills patheogenic microbes w/o significant damage to host

Antibiotic that inhibits critical metabolic pathways

isoniazid (inhibits cell wall synthesis)

Antibiotic that inhibits peptidoglycan synthesis

penicillins or B-lactam antibiotics

Antibiotic that inhibits bacterial DNA replication

Quinolones (inhibit DNA gyrase)

Antibiotics that inhibit translation of proteins by binding to ribosomes

aminoglycoside, macrolide, tetracyclines

Antibiotics that affect either function or synthesis of cell membrane

daptomycin (creates pores in membrane, PMF lost)

major mechanisms of antibiotic resistance

• reduce ability of antibiotic to reach effective concentrations

• Inactivation of antibiotic by bacterial enzyme

• Mutation of antibiotic target molecule

3.3

Lymphocytes

digest and present an antigen (portion of molecule that stimulates immune system)

MHC II proteins

• Th1: causes Inflammation that calls more macrophages

• TH2: stimulated B cells

MHC I proteins

• cytotoxic T cells: destroys infected cells by releasing granules containing perforin and granzymes

3.4

Pathogenisis

process by which microorganisms cause disease (initiated by exposure of host to pathogen)

Glycocalyx

polymers surrounding some bacterial cells that aid in attachment/biofilm formation

Virulence factor

pathogen produced substance that promoted pathogenisis of an infectious disease

Enzyme virulence factors

Collagenase

breaks down collagen in connective tissue

Streptokinase

destroys fibrin of blood clots

Coagulase

creates fibrin layer around bacteria that prevents immune detection

Cytotoxins

exotoxins that cause damage to host cell menbranes

AB toxins

exotoxin- B subunit binds to surface of host cell and A subunit enters and causes damage

Superantigens

exotoxin that causes hyperstimulated immune response

3.5