Question | Answer |
What are bactericidal antibiotics? | Drugs that kill bacteria |
What are bacteriostatic antibiotics? | Drugs that inhibit the growth of bacteria, but do not immediately kill them |
When are bactericidal antibiotics preferable to bacteriostatic antiobiotics | Imunocompromised patients, infections that are immediately life-threatening and infections that are protected from the host's immuntiy (abscess) |
What is MIC? | Minimum inhibitory concentration: the lowest conentration of a drug that inhibits bacterial growth invitro (visual) |
What is MBC? | Minimum bactericidal concentration: the lowest concentration of drug that kills bacteria invitro (plated) |
What is synergism? | An effect when the action of combining two or more drugs is significantly greater than the sum of the drug separately |
What is antagonism? | An effect when the action of combining two or more drugs is significantly lower the sum of the drug separately |
What are broad-spectrum antiobiotics? | Drugs that affect several different classes of bacterial (gram positive and gram negatives for example) |
What are narrow spectrum antiobiotics? | Drugs that are effective against a few types of bacteria (gp or gn) |
What four parts of the bacterial cell are common targets for antibacterial drugs? | Cell walls, cell membranes, ribosomes, nucleic acid and biosynthetic enzymes |
what structure do all penicillin-family antibiotics contain? | Beta lactam ring |
What are three organisms that produce b-lactamase? | Staph aureus, Haemophilus influenza and bacteroides fragilis |
How does the spectrum of the cephalosporins change from first through third generation? | Increasing spactrum for gram negative bacteria and decreasing spactrum for gram positive bacteria |
What is the spectrum of activity for each of the following: 1st generation cephalosporins? | Gram positive only |
2nd generation cephalosporins? | Increasing activity against gram negative bacteria and variable activity against gram positive bacteria |
3rd generation cephalosporins? | Even more gram negative activity and even less gram positive activity |
4th generation cephalosporins? | Extended activity against gram positive and gram negative bacteria |
What is the main advantage of cephalosporins over the other penicillins? | More resistant to beta lactamases |
Which antibiotics target cell wall synthesis? | Penicillins, vancomycin, bacitracin |
What is the spactrum of activity for vacomycin? | All gram positives including MRSA and enterococcus except VRE |
What drugs target the 50s ribosomal subunit? | Chloamphenical |
What is the spectrum of activity for chloramphenicol? | gram + and gram - anarobes |
What is the toxicity of chloramphenicol? | Bone marrow toxicity and grey baby syndrome |
Which drugs target the 30s ribosomal submit? | Aminoglycosides, tetracyclines |
Are aminoglycosides bactericidal or bacteriostatic? | Bactericidal |
What is the spectrum of activity for aminoglycosides? | Aerobic gram negative rods |
Are tetracyclines bactericidal or bacteriostatic? | Bacteriostatic |
What are the side effects of tetracyclines? | Bone deposition and discoloration, renal or hepatic toxicity, GI irritation, superinfections and teratogenic (deformaties) effects in fetus |
What drugs target messenger ribonucleic acid (mRNA) synthesis? How? | Rifampin, it inhibits RNA polymerase |
What are the side effects of rifampin | Hepatotoxicity and secretions are orange |
What drugs target tetrahydrofolate syntheses (and therefore nucleotide synthesis)? | Sulfonamides and trimethoprim |
What is a common combination of these drugs? | Trimethoprim-sulfamethoxazole |
Why are these drugs usually given together? | They have a synergistic effect |