Microbiology Chapter 12 Answers – Flashcards
Unlock all answers in this set
Unlock answersquestion
| Selective toxicity |
answer
| the ability of a chemical or drug to kill a microorganism without harming its host. |
question
| Prophylaxis |
answer
| prevents imminent infection of a person at risk |
question
| Semi-synthetic |
answer
| Drugs that are chemically modified in a laboratory after being isolated from natural sources |
question
| Narrow Spectrum |
answer
| Antimicrobials effective against a limited array of microbial types, a drug effective on mainly gram positives |
question
| Broad Spectrum |
answer
| Antimicrobials effective against a wide variety of microbial types, a drug effective on gram positives and gram negatives bacteria. |
question
| Know the characteristics of an ideal drug |
answer
| 1. Selectively toxic to the microbe but nontoxic to host cells 2. Microbial rather than microbistatic 3. Relatively soluble; functions even when highly diluted in body fluids 4. Remains potent long enough to act and is not broken down or excreted prematurely 5. Doesn’t lead to the development of antimicrobial resistence 6. Complements or assists the activities of the host’s defenses 7. Remains active in tissue and body fluids 8. Readily delivered to the site of infection 9. Reasonably priced 10.Does not disrupt the host’s health by causing allergies or predisposing the host to other infections |
question
| Know 5 mecahnisms of drug action and drugs that target each |
answer
| 1) Inhibition of cell wall synthesis- Penicillins, Monobactams, Fosfomycin, Cephalospoins, Vancomycin, Bacitracin, and Cycloserine 2) Inhibition of nucleic acid structure and function- A. Quinolones (ciprofloxacin)= Inhibits replication and transcription B. Rifampin- Inhibits RNA polymerase 3) Inhibition of protein synthesis- SITE OF ACTION A- Chloramphenical, Ertyhromycin, Clindamycin, and Oxaloidinones SITE OF ACTION B- Aminoglycosides, Tetracylines, Sterptomycin, Amikacin 4) Interference with cell membrane structure or function- Polymyxins, antifungal antibiotics, 5) Inhibition of folic acid synthesis- Sulfonamides (sulfa Drugs), Trimethoprim |
question
| Know how penicillin, cephalosporin, and vancomycin work |
answer
| react with one or more of the enzymes required for cell wall synthesis and repair Penicillin & Cephalosporin- react with one or more enzyme required to complete the synthesis of new peptidoglycan and transporting of the to proper place in the cell wall. Vancomycin- bids to the peptide side chains b/t the layers of NAG-NAM in the cell wall so the interglycine bridge crosslink cannot form. |
question
| Know the enzyme fluoroquinolones target and the enzyme rifampin targets |
answer
| Fluoroquinolones-Gyrase and topoisomerase, stops DNA replication and transcription. Rifampin- bacterial RNA polymerase |
question
| Know how sulfonamides and trimethoprim work and why stopping folic acid is a big deal |
answer
| Sulfonamides and trimethoprim- competitive inhibition Supplied to cells in high concentrations to make sure enzyme is constantly occupied with the metabolic analog rather than the true substrate Why stopping folic acid is a big deal... because it is needed to synthesize; Purines, Pyrimidines, and Amino Acids |
question
| Know the components of penicillin |
answer
| a thiazolidine ring, a beta-lactam ring, and R group- a variable |
question
| Know the four generations of cephalosporin and its advantage over penicillin |
answer
| 1) Cephalothin- 2) Cefaotiam- 3) Moxalactam- 4) Cefepime- Broad-spectrum, Resistant to most penicillinases, Cause fewer allergic reactions than penicillins, |
question
| Know 2 other beta lactam drugs |
answer
| • Imipenem • Aztreonam |
question
| Know what family streptomycin is used for, what bacterial genus prodcues that class, and the disease it is used for |
answer
| • Products of various species of soil actinomycetes in the genera Streptomyces and Micromonospora • Relatively broad spectrum because they inhibit protein synthesis • Streptomycin: Bubonic plague and tularemia and good antituberculosis agent |
question
| Know the uses of tetracycline and the 2 specific drugs we mentioned in this class |
answer
| • Bind to ribosomes and block protein synthesis ( no protien goes innto 1st binding site and blocks tRNA) • Broad-spectrum • Subgroups and uses – Gram –positive and gram-negative rods and cocci – Aerobic and anaerobic bacteria – Mycoplasmas, rickettsias, and spirochetes Doxycycline and minocycline |
question
| Know uses of erythromycin |
answer
| Blocks protein synthesis by binding two subunits together, so the ribosome can't translocate.. stops its movement |
question
| Know oxazolidones are _______ and 2 diseases it is used for |
answer
| are synthetic methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) |
question
| Know the major usage of trimethoprim |
answer
| • Pneumocystis (carimi) Jirovecl pneumonia (PCP Aids Patients) |
question
| Know that sulfonamides is ___________ synthetics |
answer
| 1st |
question
| Know the 4 drugs in the fluoroquinolones class |
answer
| Norfloxacin Ciprofloxacin Sparfloxacin Levofloxacin |
question
| Know the 2 major uses of rifampin |
answer
| • Used to treat Mycobacterial infections such as: tuberculosis and leprosy |
question
| Know what genus of bacteria produces polymyxin and daptomycin as well as which organ polymyxin is toxic to |
answer
| • Polymyxins: narrow-spectrum peptide antibiotics – From Bacillus polymyxa – toxic to the kidney • Daptomycin – Lipopeptide made by Streptomyces |
question
| Know how macrolides work and the two drugs in this class |
answer
| 1. Bind to fungal membranes and cause loss of selective permeability 2. Specific for fungal membranes because fungal membranes contain ergosterol 3. Examples: amphotericin B and nystatin 4. Mimics lipids in some cell membranes |
question
| Know the name of the four azoles and what they are used for especially know the one used in AIDS patients |
answer
| • Ketoconazole: orally and topically for cutaneous mycoses, vaginal and oral candidiasis, and some systemic mycoses • Fluconazole: used in selected patients for AIDS-related mycoses • Clotrimazole and miconazole: mainly topical ointments for infections in the skin, mouth, and vagina |
question
| Know what griseofulvin is used for and the drawbacks |
answer
| Especially active in certain dermatophyte infections such as athlete’s foot Requires several months and is relatively nephrotoxic, so only given for most stubborn cases |
question
| Know what flucystosine is the analog for |
answer
| Analog for the nucleotide cytosine |
question
| Know the two antimalarial drugs and what chemical they come from |
answer
| Quinine: extracted from the bark of the cinchona tree –Replaced by synthesized quinolines (chloroquine and primaquine) |
question
| Know the name of the amoebicide |
answer
| Metronidazole (Flagyl) |
question
| Know the name of the two major helminthic drugs and what they do to the worm |
answer
| Mebendazole and Thiabendazole • Inhibit the function of microtubules of worms, eggs, and larvae |
question
| Know 3 major modes of action on the anti-virals |
answer
| – Barring penetration of the virus into the host cell – Blocking the transcription and translation of viral molecules – Preventing the maturation of viral particles |
question
| Know that interferon is a ____________ and what it has been used to treat |
answer
| a glycoprotein 1) Reducing the time of healing and some of the complications in certain infections 2) Preventing or reducing some symptoms of cold and papillomaviruses 3) Slowing the progress of certain cancers 4) Treating a rare cancer called hairy-cell leukemia, hepatitis C, genital warts, and Kaposi’s sarcoma in AIDS patients |
question
| Define biota |
answer
| beneficial or harmless resident bacteria commonly found on or in the human body. |
question
| Describe a superinfection also know the examples we discussed |
answer
| An infection occurring during antimicrobial therapy that is caused by an overgrowth of drug resistant microorganisms. |
question
| Know the names of the three forms of antimicrobial sensitivity testing |
answer
| 1. Kirby Bauer (MH plate) 2. Tube Dilution Series 3. Stokes method |
question
| DEFINE MIC and TI |
answer
| • MIC- minimum inhibitory concentration: the smallest concentration (highest dilution) of drug that visibly inhibits growth • Therapeutic index (TI): the ratio of the dose of the drug that is toxic to humans as compared to its minimum effective dose |
question
| If a drug that worked in lab fails in the host know why? |
answer
| • If antimicrobial treatment fails, the failure is due to – The inability of the drug to diffuse into that body compartment – A few resistant cells in the culture that did not appear in the sensitivity test – An infection caused by more than one pathogen, some of which are resistant to the drug |
question
| Know figure 12.13 |
answer
| Drug Inactivation- inactivation of a drug like penicillin by penicillinase, an enzyme that cleaves a portion of the molecule and render it inactive. Decreased Permeability- the receptor that transports the drug is altered, so that the drug cannot enter the cell. Activation of Drug Pumps- Specialized membrane proteins are activated and continually pump the drug out of the cell. Change in drug binding site- binding site on target (ribosome) is altered so drug has no effect. Use of alternate metabolic pathway- the drug has blocked metabolic pathway, so the microbe circumvents it by using an alternate, unblocked pathway that achieves the required outcome. |
