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53 Cards in this Set
- Front
- Back
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What ways can bacteria acquire resistance to drugs?
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Spontaneous, random chromosomal mutations (change in protein receptor for antibiotic or a protein involved in drug transport).
Transformation: transfer of naked DNA between same species. Transduction: transfer of DNA by a bacteriophage. Conjugation: sex pilus. Transpositions: mobile genetic elements. |
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What is a B-lactam ring?
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Penicillins consists of a thiazolidine ring attached to a B-lactam ring. The B-lactam ring is required for antimicrobial activity. The R-group attached to B-lactam ring alters the pharmacological properties.
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How does penicillin prevent bacterial cell growth?
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Penicillin inactivate bacterial transpeptidases, preventing cross-linking of peptidoglycan polymers (cell wall synthesis). Penicillin also inactivates penicillin-binding proteins. They are bacteriocidal.
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What is penicillin G and V most commonly used to treat?
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Streptococci pneumoniae, Group A beta-hemolytic streptococci: Strep. pyogenes, Strep viridans.
Neisseria meningitidis (gram - aerobes) and Neisseria gonorrhoeae. Treponema pallidum (syphillis). Gram + rods: Clostridium perfringes, Bacillus species, listeria. |
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What is the difference between Penicillin G and V?
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G is given IV or IM. V is given orally.
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What are amoxicillin and ampicillin? What is the main difference between the two?
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Broader spectrum than penicillin. They cover gram - organisms: H. influenzae, Proteus mirabilis, Neisseria meningitides, E. coli. They are also used against gram + enterococcus.
Amoxicillin has better oral absorption. |
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Name the penicillinase resistant penicillins. What are they used to treat? What is a major side effect?
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IV: Methicillin, oxacillin, cloxacillin, and nafcillin are administered via IV to treat Staph aureus. Nephrotoxicity.
Oral: cloxacillin and dicloxacillin. Used for Staph aureus (cellulitis, impetigo). |
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What is the function of clavulonic acid? Name two other compounds that have similar functions.
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Irreversibly inhibits B-lactamase.
Sulbactam and tazobactam. |
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What are two major adverse effects of penicillin?
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Anaphylaxis. Performed IgE lead to anaphylactic shock, urticaria, rash.
Superinfection: Clostridium difficile can overrun the colon causing pseudomembranous enterocolitis. |
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What are the functions of the R1 and R2 groups on cephalosporins?
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Substitutions at R1 determine antibacterial activity. Substitutions at R2 determine pharmacokinetics.
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Name two bacteria that are resistant to all the cephalosporins.
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Enterococci (including Streptococcus faecalis) and MRSA
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Tell me about cefuroxime.
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Cefuroxime is a second generation cephalosporin. It has good coverage against Streptoccous pneumoniae, Haemophilus influenzae, Moraxella catarrhalis. This makes its ideal for treating community acquired bacterial pneumonia (and otitis media) when the agent is unknown. Cefuroxime is the only 2nd-ceph to have CSF penetration.
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What generation of cephalosporins are used to treat anaerobes? Name the three drugs.
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Second-generation cephalosporins. Cefotetan, cefoxitin, and cefmetazole.
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Which cephalosporins are effective against Pseudomonas aeruginosa?
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3rd/4th generations: cefoperazone, cefepime, ceftazidime.
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Which cephalosporin has the best CSF penetration? What is it used to treat?
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Ceftriaxone: meningitis, Neisseria gonorrhea.
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________ and ________, two 3rd-generation cephalosporins are excreted via the biliary tract making them useful to treat infections of the biliary tree.
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Cefoperazone and ceftriaxone.
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What are some side affects of cephalosporins?
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10% of patients allergic to penicillin will also be allergic to cephalosporin.
Alcohol intolerance. Inhibits vitamin K clotting factors: cephs with MMT side chain. Nephrotoxic when administered with diuretics. Superinfection. |
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What is aztreonam? What is its benefit.
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Monobactam that inhibits bacterial cell wall synthesis. It is used against gram - bacteria and it doesn't elicit hypersensitivity reactions like the penicillins.
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Name a couple carbapenems. What is unique about this drug? Why is it administered with cilastatin?
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Imipenem, meropenem, ertapenem. Broadest antibacterial activity of any antibiotic (doesn't cover MRSA, pseudomonas, mycoplasma).
Cilastatin inhibits renal dihydropeptidase. |
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What is vancomycin used against? What are the serious side effects?
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Vancoymcin (IV) prevents elongation/crosslinking of peptidoglycan. It is used against g+ bacteria: MRSA, antibiotic associated enterocolitis (oral - stays in GI!). Vancomycin is ototoxic and causes red man syndrome.
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How is bacitracin administered?
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It is used only topically for minor infections (gram +).
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Name the 5 antibiotics that inhibit the function of the bacterial ribosome.
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CLEan TAGS:
CLE (50s): Chloramphenicol and clindamycin, linezolid, erythromycin. TAGS (30s) Tetracycline, aminoglycosides, spectomycin. |
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When is chloramphenicol used? For what infections?
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Because of severe side effects, this agent is limited to the tx of infections when there is no alternative.
Uses: bacterial meningitis (when patient is allergic to penicillin), pregnant women with Rocky Mountain spotted fever, Salmonella typhi. |
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What are the adverse affects of chloramphenicol?
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Bone marrow suppresion (pancytopenia), hemolytic anemia in G6PD def., reticulocytopenia, gray baby syndrome.
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A patient presents to the ER with a bullet wound that penetrates the abdomen. What drugs should be administered?
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Aminoglycosides to cover gram - infections. Clindamycin to cover the anaerobes.
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Instead of draining abscesses in the lung, you can administered what drug? This same drug can also be used in severe acne.
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Clindamycin. Can cause diarrhea.
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What can cause pseudomembranous colitis? How do you treat?
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Clindamycin and penicillin family drugs. Treat with oral vancomycin or metronidazole (preferably) to kill Clostridium difficile.
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Whats the advantage of giving an MRSA patient linezolid instead of vancomycin?
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Linezolid can be taken orally.
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What are the macrolides and the mode of action of these drugs?
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Erythromycin, clarithromycin, azithromycin, telithromycin (ketolide) all inhibit the 50s ribosomal subunit to terminate protein synthesis.
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How are macrolides metabolized?
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Cytochrome P-450.
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What inhibits the absorption of tetracyclines?
What is the safest tetracycline to administer to an individual with impaired renal function? |
Tetracyclines chelate with cations, so milk products, calcium and magnesium all inhibit absorption.
Doxycycline is the safest tetracycline to take when renal function is impaired because it is excreted via bile. |
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What is tetracycline/doxycyline used for?
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Chlamydia trachomatis, Mycoplasma pneumoniae, Brucella, Rickettsia.
Also used in combination regimens for Helicobacter pylori. Doxycycline is also used for acne. |
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Side effects of tetracycline.
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GI disturbances
Phototoxic dermatitis Hepatic toxicity Discolored teeth |
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List some aminoglycosides. What is this class of drugs used against?
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Streptomycin, gentamicin, tobramycin, amikacin, neomycin.
This class of drugs is used against aerobic gram-negative enteric organisms. |
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What are the adverse effects of aminoglycosides?
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Aminoglycosides have a narrow therapeutic index. Side effects include: ototoxic, renal damage, neuromuscular blockade.
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Name the anitpseudomonial penicillin drugs. Side effects?
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Carboxypenicillin: ticarcillin, carbenicillin. SE: inhibits platelets and causes hypokalemia.
Ureidopenicillin: piperacillin, mezlocillin. |
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What drugs can cause pseudomembranous colitis? What drugs could be given to treat this condition (and how would they be given?
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Penicillin, cephalosporins, clindamycin, and flouroquinolones.
Give vancomycin or metronidazole orally. Neither will be absorbed, therefore, high concentrations will be present in the GI. |
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What is the drug of choice for outpatient treatment of community acquired pneumonia? What else is this drug used to treat?
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Macrolids: azithromycin, clarithromycin, telithromycin
Treatment of U and LRTI Syphilis Atypical organisms (legionella, mycoplasma, chlamydia). Mycobacterium avium (AIDS pt) |
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Patient with a history of arrythmias present with pneumonia due to Legionella. What drug (to treat Legionella) do you not want to send the patient home with?
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Erythromycin: caused prolonged QT syndrome. Other side effects: induces peristalsis, cholestatic hepatitis
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Patient is diagnosed with gonorrhea. The patient is also allergic to penicillin. How would you treat?
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Treat with spectinomycin (30s inhibitor) and doxycycline to cover Chlamydia trachomatis that is found in 50% of cases of urethritis.
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What four drugs are used to treat M. tuberculosis? What is the mode of action of each.
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Pyrazinamide: unknown.
Ethambutol: unknown. Isoniazid: inhibits mycolic acid synthesis. Rifampin: RNA polymerase inhibitor. |
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Child with M. tuberculosis presents with encephalopathy? Why?
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Child is being treated with isoniazid. Isoniazid inhibits pyridoxine (B6) which is a cofactor for delta-ALA synthase. High concentrations of delta-ALA damages neurons, causes cerebral edema, and demyelination in children. Only causes peripheral neuropathy in adults.
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Patient has orange/red tears, urine, feces, saliva, sweat. What is the patient being treated with? What do you do?
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Rifampin. Nothing.
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What is the main side effect of ethambutol?
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Ocular toxicity: loss of central vision and color vision.
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What drug can be used for preoperative coverage before GI surgery?
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Neomycin or netilmicin (aminoglycosides).
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Name the old antibiotic that inhibits bacterial protein synthesis by binding to 50s, but due to severe side effect it is used only to fight very resistant bugs (VRE and MRSA). Side effects include hyperbilirubinemia, pain at infusion site, and arthralgias/myalgias.
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Quinupristin/dalfopristin
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What is Clofazimine used to treat?
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Leprosy. Colors normal tissues red and lepromatic lesions black.
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How does dapsone work?
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PABA antagonist (much like sulfonamides). Results in blockage of dihydrofolic acid synthesis, therefore it inhibits DNA synthesis.
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How do the fluoroquinolones work (-floxacin)?
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Inhibit DNA gyrase (topoisomerase II) resulting in the breakage of the bacterial DNA structure.
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Why should you avoid given children flouroquinolones?
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These drugs damage cartilage. They are also associated with tendonitis and tendon rupture.
Other side effects: ciprofloxacin can cause seizures (by inhibiting GABA) in renal insufficiency. Gatifloxacin: associated with hyper/hypoglycemia. |
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How does daptomycin work?
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Kills gram positive bacteria by altering cell-membrane electrical charges.
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How does TMP work?
How does SMX work? |
Competitively inhibits dihydrofolate reductase preventing the conversion of TH2 to TH4.
Competitively inhibits production of TH4. |
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Patients on ______ should NOT be given TMP/SMX because it wound increase the levels of that drug and the patient could bleed out.
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Warfarin.
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