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Flashcards in Antibiotics 2 Deck (86):
1

carbapenem agents

imipenem-cilastatin, meropenem, ertapenem, doripenem

2

carbapenem spectrum

broad spectrum against gram-positive, gram-negative, and anaerobic organisms. stable against most beta lactamases including ESBLs and AmpCs. hits pseudomonas except ertapenem

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what bug developed high level resistance against carbapenems?

E. faecium.

4

carbapenem clinical uses

complicated UTIs, complicated intraabdominal infections, healthcare acquired pneumonia, bone and SSTI, bacterial meningitis. These are usually caused by gram negative things.

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carbapenem side effects

generally well tolerated. lower association with c. diff colitis, coag abnormalities, nephrotox or hepatotox. CNS: low incidence of seizures, but higher than other antibiotics.

6

what drug do carbapenems interact with?

substantially decrease valproic acid concentrations

7

what is great about the ertapenem halflife?

very long, allows q24h dosing. good for outpatient settings. has poor activity against pseudomonas / acinetobacter though

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what is the most active carbapenem against pseudomonas?

doripenem!

9

monobactam agents

aztreonam

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aztreoname spectrum

gram negative: enterobacteriaceae and pseudomonas. NO ACTIVITY AGAINST GRAM POSITIVE OR ANAEROBIC BACTERIA!

11

azteronam

rarely used alone empirically. alternative to penicillin to provide gram-negative coverage in combo with another agent. best used as definitive therapy for gram-neg infections. give if someone has a severe penicillin allergy

12

glycopeptide agent

vancomycin

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vancomycin mechanism of action

inhibits late stages of cell wall synth by binding to the D-Ala D-ala terminus of the nascent peptidoglycan pentapeptide. prevents elongation by inhibiting transglycosylase.

14

mechanisms of resistance to vancomycin

enterococcus (VRE) can do target modication. VISA can get a thickened cell wall. VRSA gets a plasmid-mediated transfer of the vanA gene cluster from VRE.

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vancomycin spectrum

gram pos: staphylococci (MRSA, MSSA), streptococci, enterococci, bacillus, corynebacterium.

Anaerobes: peptostrepto, actinomyces, propionibacterium, clostridium.

NO GRAM NEGATIVE ACTIVITY

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vancomycin clinical uses

SSTI especially when MRSA is suspected (purulent cellulitis). Bacteremia and endocarditis. Meningitis and ventriculitis. Pneumonia. Bone and joint infection. Neutropenic fever. Surgical prophylaxis. C. diff colitis (only the oral form)

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vancomycin side effects

nephrotox at high concentrations, infusion reactions (redman syndrome), maculopapular rash, drug fever, phlebitis, neutropenia, thrombocytopenia

18

lipopeptide agent

daptomycin

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daptomycin mechanism of action

insertion into the gram-positive cell membrane causing depolarization and ulimate cell death. Not a cell-wall active agent. resistance arises due to alteration of the cell membrane.

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daptomycin spectrum

gram pos: s. aureus, strepto/entero cocci.

Anaerobe: has invitro activity against gram-pos anaerobes

NO GRAM NEGATIVE ACTIVITY

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daptomycin clinical uses

SSTI, s. aureus bacteremia and endocarditis, osteoarticular infection, enterococcal infections. Not effective for pneumonia.

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why is daptomycin not effective for pneumonia?

it is inactivated by the surfactant!

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daptomycin side effects

CPK elevation and possible skeletal muscle damage. paresthesia, peripheral neuropathy. eosinophilic pneumonia-rare. causes myalgias.

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lipoglycopeptide agents

telavancin, dalbavancin, oritavancin.

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telavancin mechanism of action

binds to cell wall precursors like vancomycin. depolarizes cell membrane. `

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telavancin spectrum

vancomycin's spectrum PLUS VISA, VRSA, some VRE isolates

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telavancin clinical uses

SSTI, hospital acquired pneumonia. infrequently used.

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telavancin side effects

nephrotox, more so than vancomycin. GI: n/v, metallic taste. potentially teratogenic.

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dalbavancin mechanism of action

inhibition of cell wall precursors

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dalbavancin spectrum

gram positive: MRSA, MSSA, strep, coag negative staph. NO GRAM NEGATIVE ACTIVITY. Anaerobes: c. perf, c. diff, prop. acnes, peptostrepto

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oritavancin mechanism of action

inhibition of cell wall precursors, binds to pentaglycl bridging segment in peptidoglycan and inhibits transpeptidation. interaction and disruption of the cell membrane

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oritavancin spectrum

similar to dalbavancin, but active against VRE.

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dalbavancin and oritavancin clinical uses

SSTI, can be given in infusion centers (good for outpatient setting). very expensive though!!!

34

aminoglycoside agents

gentamicin, tobramycin, amikacin, streptomycin

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aminoglycoside mechanism of action

oxygen-dependent, active transport across the bacterial cell membrane. binds to the 30S subunit of ribosomes and interferes with an initiation complex, inhibiting protein synth.

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aminoglycoside mechanism of resistance

enzymatic modification, reduced uptake or decreased cell permeability, altered ribosome binding sites.

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aminoglycoside spectrum

gram neg: enterobacteriaceae and Pseudomonas
gram pos: synergy with cell wall active agent against enterococcus (cant give as monotherapy)
Amikacin: some types of mycobacteria and nocardia
Anaerobes: NONE!!!!!

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aminoglycoside clinical uses

infections caused by gram-negative bacilli. UTI. hospital acquired pneumonia when combined with a beta lactam. Enterococcal infection combined with cell wall active agent. Cystic fibrosis. Orthopedic surgery (used in antibiotic cement)

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aminoglycosides side effects

nephrotoxicity. ototoxicity. neuromusular damage (rare)

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aminoglycoside pharmacokinetics

distributed extensively into urine. distribution into tissues

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aminoglycoside pharmacodynamics

concentration dependent. High peak is important!!! biphasic killing. higher the peak, the faster the killing.

42

tetracycline agents

doxycycline, minocycline, tetracycline

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tetracycline mechanisms of action

passive diffusion through porins in gram-negative organisms. binds to 30S ribosomal subunit preventing protein synthesis

44

tetracycline mechanisms of resistance

efflux pump. ribosomal protection (through dissociation of tet from ribosomal binding sites)

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tetracycline spectrum

atypical: chlamydia and mycoplasma pneumoniae
spirochetes: borrelia, leptospira, treponema pallidum
Rickettsiae.
Gram pos: s. pneumoniae, CA-MRSA
gram neg: h. influenzae, neiserria
rapidly growing mycobacteria

46

tetracycline clinical uses

tick borne illness Drug of Choice! lyme disease, ehrlichiosis, anaplasmosis. CAP. SSTI caused by CA-MRSA. conbo therapy for h. pylori. prophylaxis for exposure to anthrax, tularemia, plague, Q fever, brucellosis

47

tetracycline side effects

GI: n/v, diarrhea.
Photosensitivity and hyperpigmentation! MAINLY IN THE HANDS
teeth and bone: tooth discoloration in kids. inhibition of bone growth in infants
Nephrotox and neurotox

48

glycylcycline agent

tigecycline

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glycylcycline chemistry/mechanism of action

9-glycl substitution enables tigecycline to overcome two major types of resistance: efflux pumps and ribosomal protection

50

tigecycline spectrum

organisms covered by tetracycline plus some tetracycline-resistant organisms. Broad spectrum: gram negative, gram positives, anaerobes. activity against stenotrophomonas. Doesn't hit pseudomonas, proteus, providencia, morganella

51

tigecycline clinical uses

FDA approved for complicated skin and soft tissue infections, intra-abdominal infection, CAP. also used for carbapenem resistant enterobacteriaceae. Not advised for treating bacteremia due to low serum concentrations

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tigecycline side effects

GI: significant N/V and diarrhea.
Transaminitis. increased mortality.

53

macrolide agents

azithromycin, clarithromycin, erythromycin.

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macrolide mechanism of action

reversible binding to 50S subunit of ribosome.

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macrolide mechanisms of resistance

decreased permeability in enterobacteriaceae. Alteration in the 50S receptor site. Alteration in the 23S ribosomal RNA of the 50S ribosomal subunit. Enzymatic inactivation

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macrolide spectrum

gram pos: s. pneumoniae, signif resistance in beta hemolytic strep. Gram neg: h. influenzae and m. catarrhalis.
Atypicals: legionella, chlamydia, mycoplasma
Anaerobes: actinomyces

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macrolides clinical uses

uncomplicated upper and lower respiratory tract infections. Mycobacterial infection. H. pylori in combo with other agents.

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macrolides side effects

GI: abdominal cramps, N/V, diarrhea. Thrombophlebitis with erythromycin. Cardiac: QT prolongation -> torsades de pointes

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what is the safest macrolide to use?

azithromycin! only has one interaction. much safer than the other macrolides

60

clindamycin mechanism of action

binding to 50S ribosomal subunit preventing protein synth.

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clindamycin mechanisms of resistance

alteration in 23S ribosomal RNA of 50S ribosomal subunit. Alteration in 50S ribosomal proteins of the receptor site. Enzymatic inactivation

62

clindamycin spectrum

gram pos: streptococci including group B strep. Staph aureus.
NO GRAM NEGATIVE ACTIVITY
Anaerobes: B. fragilis, clostridium, peptostreptococcus, fusobacterium, prevotella.
Toxoplasmosis, plasmodium falciparum

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clindamycin clinical uses

tends to be an alternative treatment, mainly for surgical prophylaxis and SSTIs caused by staph aureus.
Combo with penicillin for toxic shock. combo with quinine for falciparum malaria

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clindamycin side effects

diarrhea, pseudomembranous colitis

65

oxazolidinone agents

linezolid, tedizolid.

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oxazolidinone mechanism of action

binds to 23 S ribosomal RNA of the 50S subunit inhibiting protein synthesis

67

linezolid and tedizolid spectrum

activity against gram-positives: staphylococci, enterococci, streptococci. NO GRAM NEGATIVE ACTIVITY. poor activity against anaerobes.

68

linezolid and tedizolid clinical uses

tedi is approved for SSTI. linezolid is used for enterococcal infection, nosocomial pneumonia caused by s. aureus, CAP caused by s aureus, SSTI. not recommended for s. aureus bacteremia

69

linezolid and tedizolid side effects

hematologic toxicity, reversible myelosuppression, mitochondrial toxicity, serotonin syndrome

70

fluoroquinoline agents and mechanism of action

end in -floxacin. Inhibit DNA gyrase and inhibit topoisomerase IV

71

fluoroquinolone spectrum

gram pos: s. aureus, s. pneumoniae, enterococcus (poor).
gram neg: enterobacteriaceae, h flu, p aeruginosa, atypicals.
mycobacterium
moxifloxicin has moderate activity against anaerobes

72

fluoroquinolone clinical uses

resistance in enterobacteriaceae problematic. UTI. GI and abdominal infections: traveler's diarrhea. STDs: gonoccoal urethritis, chlamydial infection. Respiratory tract infections. Bone and joint infection. cutaneous anthrax. adjunctive therapy in MDR TB

73

fluoroquinolone side effects

GI: mild
CNS: headache, dizziness, confusion
Tendinitis and tendon rupture rare.
QT prolongation

74

metronidazole mechanisms of action

interacts with DNA to cause a loss of helical DNA structure and strand breakage resulting in inhibition of protein synthesis

75

metronidazole antimicrobial spectrum

anaerobes: b. fragilis, clostridial species.
Protozoa

76

metronidazole clinical uses

C. diff diarrhea. intra-abdominal infections. surgical prophylaxis in colon surgery. trichomoniasis.

77

rifamycin agents

rifampin, rifabutin, rifaximin

78

rifamycin mechanism of action

bind to DNA dependent RNA polymerase inhibiting RNA synthesis

79

rifamycin spectrum

gram pos: staphylococci, streptococci, c. diff, listeria
gram neg: h flu, n meningitidis, h. pylori
mycobacterium

80

clinical uses for rifamycins

rifampin: m. tuberculosis infection. adjunct in endocarditis. prophylaxis for n. meningitidis
rifabutin: alternative to rifampin for MAC or tuberculosis
rifaximin: hepactic encephalopathy, recurrent C. diff, traveler's diarrhea

81

isoniazid mechanism

inhibition of synthetic pathways of mycolic acid

82

pyrazinamide and ethambutol mechanisms of action

pyrazinamide: unknown
ethambutol: inhibits arabinosyl transferase enzymes involved in biosynth of cell walls

83

bacterial anti-metabolite agents

trimethoprim-sulfamethoxazole (bactrim)

84

trimeth-sulfameth mechanism of action

sulfa: interferes with bacterial folic acid synth
trimeth: inhibits dihydrofolic acid reduction to tetrahydrofolate

85

trimeth-sulfameth spectrum

gram pos: CA-MRSA, MSSA. not ideal for beta hemolytic strep. listeria
Gram neg: enterobacteriaceae. toxoplasmosis, nocardia, pneumocystis. NO ANAEROBES

86

trimeth-sulfameth clinical uses

prophylaxis and treatment of pneumocystitis jiroveccii pneumonia. toxoplasmosis encephalitis. UTI. listeria meningitis. CA-MRSA