Bacteriology Part IV Flashcards
What are antimicrobials?
drugs that destroy microbes, prevent their multiplication, or growth, or prevent their pathogenic effect.
Alexander Fleming discovered what?
Penicillin
What is an antibiotic?
an antibiotic is a low molecular substance PRODUCED BY a microorganism that at a low concentration kills other microorganisms
antimicrobial
a substance (natural, semisynthetic, or synthetic) that kills or inhibits another microorganism. causes little to no damage to the host
all antibiotics are antimicrobials but not all antimicrobials are antibiotics
true
What are the three types of antimicrobials?
1) Natural
2) Semisynthetic
3) Synthetic
What are natural antimicrobials produced by? (true antibiotics) Examples?
produced by bacteria or fungus (streptomycin, penicillin, tetracycline)
What are semisynthetic antimicrobials? Examples?
a natural compound thats been chemically altered
-ampicillin, amikacin
What are synthetic antimicrobials? Examples?
chemically designed in a lab
-sulfonamide, enrofloxacin, marbofloxacin
Antimicrobials are classified in 4 ways:
1) Chemical structure
2) Mode of action
3) Type of antimicrobial activity
4) Spectrum of antimicrobial activity
Classification of antimicrobials: Mode of Action: Cell wall synthesis
B lactam antibiotics
What are B lactam antibiotics?
inhibit peptidoglycan synthesis; inhibits penicillin binding proteins
Examples of B lactam antibiotics?
Penicillin, ampicillin, cephalosporins
What is B lactamase?
B lactamase is an enzyme active in antibiotics that can cleave B lactam antibiotic causing resistance
Classification of antimicrobials: Mode of action: protein synthesis inhibitors:
1) aminoglycosides
2) Tetracyclines
3) Macrolides
Classification of antimicrobials: Mode of action: DNA synthesis inhibitors:
1) Quinolones
2) Metronidazole
Classification of antimicrobials: Mode of action: RNA synthesis inhibitors
1) Rifampin
2) Mupirocin
Classification of antimicrobials: Mode of action: Folic acid synthesis inhibitors:
1) Sulfamides
2) Trimethoprim
What are broad spectrum antibiotics?
Useful against gram positive and negative organisims
Narrow spectrum antibacterials?
useful against either gram positive or negative not both
what is Bactericidal (Suicidal)?
kills bacteria
What is Bacteriostatic?
inhibits bacterial growth
What is the Antimicrobial Susceptibility Test (AST)?
AST is a test to determine whether a bacterium is susceptible to an antimicrobial treatment
What are the 2 types of AST available?
1) Disk diffusion test (kirby bauer test)
2) Broth/Agar dilution test
What is the minimum inhibitory concentration (MIC)?
the minimum amount of drug required to inhibit bacterial growth
What is the susceptibility break point?
the drug concentration where above it the organism is considered resistant, below it, it is susceptible to drug
What are the three break point values?
Susceptible
Intermediate
Resistant
For AST - Kirby Bauer test, what MUST you use?
you must use a bacterial isolate in PURE culture
Two types of antimicrobial resistance?
1) Innate resistance
2) Acquired resistance
What are the 4 ways Bacteria can block entry of antimicrobial drug?
1) block entry into cell
2) Inactivating enzymes
3) Altering target molecule
4) Efflux or ejection of antibiotic
