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73 Cards in this Set
- Front
- Back
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from where do humans obtain folic acid?
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present in green, leafy vegetables in the diet
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what is formed from folic acid in humans?
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tetrahydrofolic acid
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how do bacteria differ from humans in folate metabolism?
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bacteria cannot take in preformed folate, where as humans can
the bacteria must produce it from its precursors (dihydropteroate synthetase forms dihydrofolic acid from para-aminobutyric acid) and then form tetrahydrofolic acid |
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why is folate an important vitamin?
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it is a precursor for tetrahydrofolic acid which is an important co-factor for various 1-carbon transfer reactions used in the synthesis of amino acids, purines, and pyrimidines
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what enzyme is blocked by sulfonamides?
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dihydropteroate synthetase (aka dihydrofolic acid synthetase)
enzyme responsible for forming dihydrofolic acid from PABA in bacteria (necessary since they cannot take in preformed folate like humans can) |
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what enzyme is blocked by trimethoprim?
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dihydrofolic acid reductase
enzyme responsible for converting dihydrofolic acid into tetrahydrofolic acid |
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what are the sulfonamides?
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sulfisoxazole
sulfamethoxazole |
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what is the most common antibiotic associated with skin rashes?
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sulfamethoxazole
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why can sulfamethoxazole not be given in the last trimester of pregnancy?
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it displaces bilirubin from albumin in the plasma and causes neonatal death
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what is the drug of choice in Pneumocystis carinii pneumonia?
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Sulfamethoxaxole + Trimethoprim combo
administered as a high dose IV, not oral |
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what is the function of type II topoisomerase?
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when DNA is being copied, topoisomerase resolves super helical twists which increase tension in the DNA strands and interfere with further unwinding
OR separate catenanes that are created transcription of circular DNA |
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what are the two subtypes of type II topoisomerase?
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DNA gyrase
topoisomerase IV |
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what is the difference between topoisomerase I and topoisomerase II?
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topoisomerase I breaks only 1 strand of a DNA molecule to change the coiling (relieve tension caused by supercoils)
topoisomerase II breaks both strands of a DNA molecule to change the coiling |
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what are catenanes?
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chains of 2 rings of bacterial DNA formed by transcription
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how do quinolones cause double-stranded DNA breaks and bacterial killing?
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inhibit passage of the T-segment of DNA past the G-segment in topoisomerase
inhibit re-ligation of the G-segment of DNA by topoisomerase promote topoisomerase subunit dissociation (allow DNA to break, but not to pass or to be re-ligated) |
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what are the steps in the action of type II topoisomerase?
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1) G-segment of DNA (DNA with supercoil) associates with type II topoisomerase
2) T-segment of DNA (guide DNA) associates with type II topoisomerase 3) G-segment is cleaved (double-stranded break) 4) T-segment passes through G-segment and through the enzyme, and finally leaves the enzyme 5) G-segment is re-ligated by the topoisomerase |
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what is the effect of fluoride atoms in the structure of quinolones (fluoroqunolones)?
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increases the spectrum, as compared to those quinolones without the flouride atoms
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what makes quinolones special?
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they are oral antibiotics for gram negative infections
**can also be given IV in hospital **even P. aeruginosa is susceptible |
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GI absorption of what antibiotics is inhibited by divalent metal cations (aluminum, magnesium, calcium)?
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quinolones (ciprofloxacin, levofloxacin, moxifloxacin)
tetracyclines (doxycycline, minocycline) |
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what is the function of bacterial pyruvate-ferredoxin oxidoreductase? why is this important to antibiotic therapy?
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converts pyruvate to acetyl-CoA while simultaneously reducing ferredoxin
reduced ferredoxin transfers electrons to metronidazole (antibiotic), thereby activating it |
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what is the function of bacterial nitroreductase? why is this important to antibiotic therapy?
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oxidizes NADPH to NADP+
simultaneously, it can transfer the electrons to metronidazole (antibiotic), thereby activating it |
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what are the two activation pathways for metronidazole?
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PFOR-dependent: pyruvate-ferredoxin oxidoreductase-dependent (PFOR reduces ferredoxin, which then transfers electrons to metronidazole)
nitroreductase-dependent: simultaneous oxidation of NADPH and reduction of metronidazole reduced metronidazole is the active form |
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in what type of environment is the active form of metronidazole favored?
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anaerobic environments
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why is metronidazole not used to treat C. difficile?
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there is too much resistance encountered
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what antibiotics are bactericidal, including at least partial bactericidal activity against resting microorganisms?
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streptomycin
kanamycin gentamicin tobramycin amikacin **aminoglycosides** |
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what antibiotics are bactericidal only against proliferating microorganisms?
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penicillins
cephalosporins bacitracin vancomycin **cell wall inhibitors** |
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what antibiotics are bacteriostatic?
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chloramphenicol
tetracyclines erythromycin clindamycin **protein synthesis inhibitors** |
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why can antibiotic cell wall inhibitors not be combined with protein synthesis inhibitors?
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the protein synthesis inhibitors are bacteriostatic, so they inhibit the proliferation of the bacteria
cell wall inhibitors require proliferation of bacteria in order to have a bactericidal activity, so if combined with with inhibitors of protein synthesis they have no effect on the bacteria |
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Tx options for intestinal perforation into peritoneal cavity
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1) gentamicin (gram-neg) + clindamycin (anaerobes)
2) imipenem |
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synergy between what two types of drugs is utilized in Tx for bacterial endocarditis?
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penicillins
aminoglycosides synergy causes increased bacterocidal action |
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synergy between what drugs is utilized for Tx of Pseudomonas aeruginosa infections?
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piperacillin
aminoglycosides |
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synergy between what drugs is utilized for Tx of UTIs?
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sulfamethoxazole
trimethoprim |
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why does the simultaneous administration of two drugs with different mechanisms of action decrease the incidence of resistance?
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two independent mutations would be required to confer resistance to the bacteria; the simultaneous development of two such mutations is highly unlikely
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why are bacteria relatively resistant penicillins after treatment with tetracycline?
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tetracycline inhibits bacterial proliferation, but penicillin is most effective against rapidly proliferating bacteria
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what drugs are commonly used to treat UTIs caused by E. coli?
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Trimethoprim/Sulfamethoxazole combination
ciprofloxacin |
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what drugs are commonly used to treat UTIs caused by Proteus mirabilis?
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trimethoprim/sulfamethoxazole combination
ciprofloxacin (not in children) ampicillin in children amoxicillin in children ampicillin/gentamycin combination in severe problem |
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what drugs are commonly used to treat UTIs caused by Klebsiella?
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trimethoprim/sulfamethoxazole combination
ciprofloxacin (not in children) ampicillin in children amoxicillin in children ampicillin/gentamycin combination in severe problem |
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what drugs are commonly used to treat UTIs caused by Staphylococci?
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trimethoprim/sulfamethoxazole combination
ciprofloxacin (not in children) ampicillin in children amoxicillin in children ampicillin/gentamycin combination in severe problem |
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what drugs are commonly used to treat UTIs caused by Pseudomonas aeruginosa?
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ciprofloxacin
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what drugs are commonly used to treat UTIs? against what microorganisms are they effective?
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trimethoprim/sulfamethoxazole combination (klebsiella, E. coli, P. mirabilis, Staph)
ciprofloxacin (E. coli, P. mirabilis, Klebsiella, P. aeruginosa, Staph) - cannot be used in kids Ampicillin (E. coli, P. mirabilis, Staph) - used in kids Amoxicillin (E. coli, P. mirabilis, Staph) - used in kids ampicillin/gentamicin combination (E. coli, P. mirabilis, Staphylococci, Klebsiella, P. aeruginosa) - used in severe infections |
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what are the types of skin infections?
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cellulitis
impetigo infected skin breaks |
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what is the usual cause of skin infections?
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Streptococcus pyogenes
sometimes caused by Staphylococcus aureus or Staphylococcus epidermidis |
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what antibiotics are commonly used for Tx of skin infections caused by S. pyogenes?
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oral amoxicillin/clavulanic acid combination
oral cephalexin |
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what antibiotics are commonly used for Tx of skin infections caused by S. aureus?
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IV nafcillin
IV cefazolin |
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what antibiotics are commonly used for Tx of skin infections caused by S. epidermidis?
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IV nafcillin
IV cefazolin |
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what antibiotics are commonly used for Tx of pressure ulcers?
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usually caused by E. coli/P. aeruginosa anaerobes
pipericillin/tazobactam combination imipenem/cilistatin combination oral moxifloxacin |
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what antibiotics are commonly used for Tx of diabetic ulcers?
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usually caused by E. coli/P. aeruginosa anaerobes
pipericillin/tazobactam combination imipenem/cilistatin combination oral moxifloxacin |
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what antibiotics are commonly used for Tx of nosocomial MRSA skin infections?
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Vancomycin
Linezolid Daptomycin |
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what antibiotics are commonly used for Tx of community-acquired MRSA skin infections?
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trimethoprim/sulfamethoxazole combination (useless for abscess due to MRSA)
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what antibiotics are commonly used for Tx of bone and joint infections?
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usually caused by S. aureus or S. pyogenes
Nafcillin cefazolin pipericillin/tazobactam combination Vancomycin if MRSA suspected |
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what antibiotics are commonly used for Tx of meningitis caused by Streptococcus pneumoniae?
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ceftriaxone
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what antibiotics are commonly used for Tx of meningitis caused by Neisseria meningitidis?
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ceftriaxone (DOC)
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what antibiotics are commonly used for Tx of Lyme disease?
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doxycycline
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what antibiotics are commonly used for Tx of syphilis?
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Benzathine Penicillin G
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what antibiotics are commonly used for Tx of gonorrhea?
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1 dose of ceftriaxone IM
doxycycline is also given BIDx10 days to kill chlamydia which coinfects 50% of patients |
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what antibiotics are commonly used for Tx of pelvic inflammatory disease caused by Chlamydia?
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doxycycline BIDx10 days
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what antibiotics are commonly used for Tx of pelvic inflammatory disease caused by Neisseria gonorrhea?
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cefoxitin, 1 dose IM
(second gen cephalosporin) |
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what antibiotics are commonly used for Tx of pelvic inflammatory disease caused by Bacteroides fragilis?
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cefoxitin, 1 dose IM
(second gen cephalosporin) |
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what antibiotics are commonly used for Tx of pelvic inflammatory disease caused by E. coli?
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cefoxitin, 1 dose IM
(second gen cephalosporin) |
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what antibiotics are commonly used for Tx of sinusitis and otitis media caused by Streptococcus pneumoniae?
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amoxicillin
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what antibiotics are commonly used for Tx of sinusitis and otitis media caused by Haemophilus influenzae?
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amoxicillin/clavulanic acid combination
trimethoprim/sulfamethoxazole combination levofloxacin (adults only) azithromycin H. influenzae is a gram-negative rod |
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what antibiotics are commonly used for Tx of sinusitis and otitis media caused by Moraxella catarrhalis?
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amoxicillin/clavulanic acid combination
trimethoprim/sulfamethoxazole combination levofloxacin (adults only) azithromycin M. catarrhalis is a gram-negative rod |
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what antibiotics are commonly used for Tx of pneumonia caused by Streptococcus pneumoniae?
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clarithromycin or azithromycin
doxycycline levofloxacin or moxifloxacin |
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what antibiotics are commonly used for Tx of pneumonia caused by Haemophilus influenzae?
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clarithromycin or azithromycin
doxycycline levofloxacin or moxifloxacin |
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what antibiotics are commonly used for Tx of pneumonia caused by mycoplasma pneumoniae?
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clarithromycin or azithromycin
doxycycline levofloxacin or moxifloxacin |
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what antibiotics are commonly used for Tx of pneumonia caused by Staphylococcus aureus?
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clarithromycin or azithromycin
levofloxacin or moxifloxacin |
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what antibiotics are commonly used for Tx of pneumonia caused by Klebsiella pneumoniae?
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levofloxacin or moxifloxacin
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what antibiotics are commonly used for Tx of pneumonia caused by Chlamydia pneumoniae?
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clarithromycin or azithromycin
doxycycline |
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what antibiotics are commonly used for Tx of pneumonia caused by Legionella pneumophila?
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erythromycin
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what are the bacteria that cause atypical pneumonia?
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Chlamydia pneumoniae (Tx with clarithromycin, azithromycin, or doxycycline)
Legionella pneumophila (Tx with erythromycin) |
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what drugs are commonly used if a patient has a severe pneumonia that requires hospitalization?
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ceftriaxone/azithromycin combination (both IV)
levofloxacin (IV) moxifloxacin (IV) |
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what antibiotics are commonly used for Tx of strep throat?
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caused by Strep pyogenes
Penicillin VK sometimes amoxicillin |
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what is Penicillin VK?
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penicillin V with potassium salt
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