Broad-spectrum
Antibacterial drugs that can inhibit a variety of gram-positive and gram-negative bacteria.
Narrow-spectrum
Antibacterial drugs that are only active against a limited variety of bacteria
Bacteriostatic
Level of antimicrobial activity that inhibits the growth of an organism.
Minimum inhibitory concentration
The lowest concentration that inhibits the growth of the organism.
Minimum bactericidal concentration
The lowest concentration that kills 99.9% of the population.
Antibiotic combinations
Used to broaden the antibacterial spectrum for empirical therapy or the treatment of polymicrobial infections, prevent the emergence of resistant organism during therapy, and achieve a synergistic killing effect.
Antibiotic antagonism
Combination of antibiotics in which the activity of one antibiotic interferes with activity of other.
B-Lactamase
An enzymes that hydrolyzes the B-lactam ring in the B-lactam class of antibiotics, thus inactivating the antibiotic.
Penicillinases
Enzyme that breaks down penicillins and inactivates them.
Cephalosporinaes
Enzyme that breaks down cephalosporin drugs.
Carbapenemases
Enzyme that breaks down carbapenem drugs.
Penicillins, cephalosporins, cephamycins, carbapenems, monobactams
Bind PBPs and enzymes responsible for peptidoglycan synthesis
B-lactam inhibitors
Binds B-lactamases and prevents enzymatic inactivation of B-lactam.
B-lactam antibiotics
Most common type of antibiotic, generally act as bactericidal agents that inhibit cell synthesis.
Vancomycin
Inhibits cross-linkage of peptidoglycan layers. Inactive against gram-negative bacteria since it is too big to pass through the pores of the outer membrane to reach peptidoglycan.
Daptomycin
Causes depolarization of cytoplasmic membrane, resulting in disruption of ionic concentration gradients. Potent against gram-positive bacteria, but not gram-positive due to protective cell wall over cytoplasmic membrane.
Bacitracin
Inhibits bacterial cytoplasmic membrane and movement of peptidoglycan precursors. Typically applied topically and used for gram-positive bacteria. Resistance is due to failure of antibiotic ability to penetrate bacterial cell.
Polymyxins
Cyclic polypeptide that acts like a detergent on bacterial membranes increasing membrane permeability and causing cell death. B and E polymixins can cause serous nephrotoxicity and their use is limited. Most active against gram-negative rods.
Isoniazid, ethionamide
Inhibit mycolic acid synthesis in mycobacteria.
Ethambutol
Inhibits arabinogalactan synthesis
Cycloserine
Inhibits cross-linkage or peptidoglycan layers by inhibiting two enzymes D-alanine-D-alanine synthetase and alanine reacemase which catalyze cell wall synthesis.
Aminoglycosides
Produce premature release of aberrant peptide chains from 30S ribosomes to inhibit protein synthesis. Most active against gram-negative bacteria. Most common are amikacin, gentamicin, tobramycin
Tetracylines
Prevent polypeptide elongation at 30S ribosome to inhibit protein synthesis by binding irreversibly to the 30S ribosome and blocking tRNA from binding. Broad spectrum antibiotic active against gram-positive and some gram-negative bacteria.
Glycylcyclines
Bind to 30S ribosome and prevent initiation of protein synthesis and are similar to tetracyclines, but more active against gram-negative bacteria and rapidly growing mycobacteria. Tigecylcine.
Oxazolidinone
Prevents initiation of protein synthesis at 50S ribosome, not active against gram-negative bacteria. Linezolid, narrow spectrum antibiotic against resistant strains of gram-positive bacteria.
Chloramphenicol
Broad spectrum antibiotic that is not used widely since it disrupts protein synthesis in bone marrow as well as bacteria. Reversibly binds to 50S ribosomal subunit.
Macrolides, Ketolides, Clindamycin, Stretogramins
Prevent polypeptide elongation at 50S ribosomes to inhibit protein synthesis. Broad spectrum antibiotic against gram-positive and gram-negative bacteria and some mycobacteria.
Quinolones
Bind alpha subunit of DNA gyrase (topoisomeriase type II or IV) to inhibit nucleic acid synthesis. Fluoroquinolones are excellent broad spectrum against gram-positive and gram negative bacteria.
Rifampin, Rifabutin
Prevent transcription by binding DNA-dependent RNA polymerase. Active against Mycobacterium tuberculosis and gram-positive bacteria.
Metronidazole
Disrupts bacteria DNA (is cytotoxic compound)
Sulfonamides
Antimetabolite that inhibits dihydropteroate synthase and disrupt folic acid synthesis
Dapsone
Antimetabolite that inhibits dihydropteroate synthase
Trimethoprim
Antimetabolate that inhibits dihydrofolate reductase and disrupts folic acid synthesis.
Clofazimine
lipophilic antibiotic that binds tightly to mycobacterial DNA.
Pyrazinamide
Similar to phagolysosomes and is active against M. tuberculosis at low pH.
1935
Year the first "sulfa" drug was ushered in a new era in medicine.
Alexander Fleming
First person to discover the mold Penicillium.
Empirical therapy
The initiation of treatment prior to determination of a firm diagnosis.
Serine proteases
Enzymes that catalyze the ross-links and chains of peptidoglycan. Also called penicillin-binding proteins such as transpeptdases, transglycosylates, carboxypeptidases.
Porins
Transmembrane proteins that allow transport of molecules such as antibiotics into the cell.
Extended Spectrum B-lactamases
Also known as class A B-lactamases. Single point mutations on B-lactamases that have activity against all penicillin and cephalosporin. Encoded on a plasmids.
Class B B-Lactamases
Use zinc-dependent metalloenzymes that have a broad-spectrum against all B-lactam antibiotics
Class C B-lactamases
Primarily cephalosporinases encoded on the bacterial chromosome.
Class D B-lactamases
Penicillinases found primarily in gram-negative rods
Penicillin G
Used mainly as an intravenous drug because it is inactivated by gastric acid and incompletely absorbed.
Methacillin and Oxacillin
Penicillinase-resistant penicillins