02 Antimicrobials & Resistance Flashcards
Substances that inhibit, kill, or destroy microorganisms
Antimicrobial agents
Streptomycin came from ____ spp.
Streptomyces
Penicillin came from ___
P. notatum
Examples of narrow spectrum antimicrobials
Penicillin G,
Bacitracin
Clindamycin
Erythromycin
Polymyxin B
Vancomycin
Examples of broad spectrum antimicrobials
Tetracycline
Ampicillin
Cephalosporin
Source of cephalosporins
Acromonium
Structurally similar to penicillin but better able to withstand B-lactamase and more modifiable
Cephalosporins
The original cephalosporin
Cephalosporin C
Inhibits enzymes needed for peptidoglycan formation
Beta-lacram drugs
Identify the cephalosporin generation:
Cefprozil
1
Identify the cephalosporin generation:
Cefuroxime
1
Identify the cephalosporin generation:
Cefixime
2
Identify the cephalosporin generation:
Cefotaxime
2
Identify the cephalosporin generation:
Ceftazidime
3
Identify the cephalosporin generation:
Cefepime
4
Identify the cephalosporin generation:
Ceftaroline
5
Identify the cephalosporin generation:
Ceftobiprole
5
Identify the cephalosporin generation:
narrow spectrum
1
Identify the cephalosporin generation:
extended spectrum
2
Identify the cephalosporin generation:
broad spectrum
3
Identify the cephalosporin generation:
extended spectrum
4
T/F: Carbapenems are effective for MRSA and VRE
F
Cell wall synthesis inhibitor that is effective for Gr (-) enterics and Pseudomonas
Carbapenems
Cell wall synthesis inhibitors
Monobactams
Carbapenems
Binds to terminal D-Ala-D-Ala of the pentapeptidyl-glycosyl peptidoglycan intermediates
Glycopeptides
DOC for MRSA
Vancomycin
Glycopeptides are ___ spectrum
narrow
Glycopeptides are limited to Gr ___ organisms only
positive
The use of this drug requires the monitoring of blood when used for more than three days
Vancomycin
Gr (+) organisms that are resistant to glycopeptides
Erysipelothrix
Lactobacillus
Pediococcus
Leuconostoc
Inhibits the synthesis of the peptidoglycan precursors in the cytoplasm
Cycloserine
2nd line drug for TB
Cycloserine
Act like detergents which interact with phospholipids
Polymyxins
Agent of last resort to P. aeruginosa and Acinetobacter infection
Polymyxins
Source of bacitracin
Bacillus licheniformis
A topical antibiotic that inhibits the transport of lipid-bound precursors across the cytoplasmic membrane
Bacitracin
Disrupts the membranes of Gr (+) bacteria
Lipopeptides
Effective for VRSA, VRE, MRSA
Lipopeptides
Binds to dihydropteroate synthase and is a competitive inhibitor of folic acid synthesis
Sulfonamides and sulfamethoxazole
Blocks the step leading to formation tetrahydrofolate by preventing dihydrofolate reductase mediated recycling of folate coenzymes
Trimethoprim
Used for chronic UTI and enterics such as E. coli and H. moraxella
Trimethoprim
Bind and interfere with DNA gyrase and topoisomerase IV
Fluoroquinolones
Effective for anaerobes, microaerophiles, protozoans, Gardnerella, C. difficile
Metronidazole
Prophylaxis for N. meningitidis
Rifamycins
Inhibits translation through inhibition of elongation step; preventing attachment of amino acid
chloramphenicol
Toxic effects of chloramphenicol
Aplastic anemia
Gray baby syndrome
Inhibits protein synthesis by binding to 23s RNA of the 50s ribosomal subunit inhibiting transfer RNA
Macrolides
T/F: macrolides are mostly bacteriostatic
T
DOC for CAP
Clindamycin
DOC for L. pneumophila
Erythromycin
The overuse of clindamycin leads to ___
pseudomembranous colitis
Inhibits protein synthesis by binding reversibly to the 30s ribosomal subunit
Tetracycline and doxycycline
Used for intracellular pathogens such as Mycoplasma, Spirochetes, Shigella
Tetracycline and doxycycline
Used for Mycoplasma, Treponemes, and Rickettsia
Macrolides
Contraindicated for pregnant women
Tetracycline and doxycycline
Often used together with penicillin in order to diffuse and enter bacterial cell
Aminoglycosides
Used for S. pyogenes infection
Aminoglycosides
1st Line TB drugs
Isoniazid
Rifampicin
Pyrazinamide
1st Line TB drug:
interferes with formation of mycolic acid
Isoniazid
1st Line TB drug:
inhibit DNA dependent RNA polymerase
Rifampicin
1st Line TB drug:
Bactericidal
Pyrazinamide
2nd Line TB drugs
Ethambutol
Streptomycin
2nd Line TB drug:
Inhibit mycolic acid
Ethambutol
2nd Line TB drug:
Aminoglycoside that inhibits the 30s ribosomal unit
Streptomycin
Changes that result in observably reduced susceptibility of an organism to a particular antimicrobial agent
biologic resistance
Decreased pH leads to ___, ___, and ___ resistance
aminoglycoside
erythromycin
clindamycin
Increased pH leads to ___ resistance
tetracycline
Anaerobic environment decreased the activity of ___
aminoglycoside
Mg and Ca conc. decreases the activity of ___ to ___
aminoglycosides
P. aeruginosa
Folate metabolites can decrease activity of ___ and ___ against ___
sulfonamide
trimethoprim
enterococci
Mechanism of intrinsic resistance:
sessile bacterial communities
biofilms
Mechanism of intrinsic resistance:
irreversibly attached to solid surfaces
biofilms
Mechanism of intrinsic resistance:
embedded in exopolysaccharide matrix
biofilms
Mechanism of intrinsic resistance:
leads to decreased penetration of antibiotics, formation of persister cells
biofilms
The resistance of S. saprophyticus to novobiocin is an example of ___ resistance
intrinsic
Genus of bacteria that have intrinsT/Fic resistance of polymyxins
Proteus
Providencia
Morganella
Edwardsiella
T/F: acquired resistance is unpredictable
T
Causes of acquired resistance
prior exposure
changes in the genetic make up
The gene mutated in S. pneumoniae, leading to acquired macrolide resistance
mefA gene
The gene mutated in S. aureus and Enterococcus, leading to acquired macrolide resistance
mrsA gene
The gene mutated in S. agalactiae, leading to acquired macrolide resistance
mreA gene
