Microbiology Flashcards
(21 cards)
There are four major sites in the bacterial cell that are sufficiently different from the human cell that they serve as the basis for the action
of clinically effective drugs
cell wall, ribosomes, nucleic acids, and cell membrane
Selective toxicity
selective inhibition of the growth of the microorganisms without damage to the host.
Broad-spectrum antibiotics
are active against several types of microorganisms.
Narrow-spectrum antibiotics
are active against one or very few types.
Bactericidal drugs
kill bacteria, whereas bacteriostatic drugs inhibit the growth of the bacteria but do not kill.
Penicillins and cephalosporins
act by inhibiting transpeptidases, the enzymes that catalyze the final cross-linking step in the synthesis of peptidoglycan.
Exposure of the bacterial cell to lysozyme,
is present in human tears, results in degradation of the peptidoglycan and osmotic rupture similar to that caused by penicillin.
They are also bactericidal and acts on Gram positive bacteria.
Glycopeptides: Vancomycin, Bacitracin & Cycloserine
act at the level of the 30S ribosomal subunit.
Aminoglycosides & tetracyclines
act at the level of the 50S ribosomal subunit.
chloramphenicol, erythromycins, and clindamycin
Inhibition of mRNA Synthesis
Rifampin
Inhibition of Precursor Synthesis :
Sulfonamides& Trimethoprim;
Inhibition of DNA Synthesis
Fluoroquinolones
Antifungal drugs
These drugs have selective toxicity because fungal cell membranes contain ergosterol, whereas human cell membranes have cholesterol.
Bacteria, do not have sterols in their membranes and therefore are resistant to these drugs.with the exception of
Mycoplasma
Polymyxins
It is active against gram-negative rods, especially P. aeruginosa
Daptomycin
It is active against gram-positive cocci. such as S. aureus
Amphotericin B
disrupts fungal cell membranes by binding at the site of ergosterol in the membrane).
Isoniazid
inhibits the synthesis of mycolic acid; a long chain fatty acid found in the cell wall of mycobacteri
Isoniazid
tuberculosis and other mycobacterial diseases.
Metronidazole
effective against anaerobic bacteria and certain protozoa because it acts as an electron sink, taking away the electrons that the organisms need to survive. It also forms toxic intermediates that damage DNA.
