Bacterial Drugs Flashcards by Richard Buksch

b-lactam cell wall inhibitors MOA

Looks like D-ala-D-ala; Binds PBPs (transpeptidases) and blocks peptidoglycan cross-linking; Disrupts integrity of bacterial cell wall

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b-lactam cell wall inhibitors Adverse Effects

All beta lactams are associated with allergic reactions including anaphylaxis, rashes, nephritis

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penicillin G

B lactam cell wall inhibitor

simple penicillins

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amoxicillin

B lactam cell wall inhibitor

extended spectrum penicillins

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nafcillin

B lactam cell wall inhibitor

b-lactamase-resistant penicillins

Associated with interstitial nephritis

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piperacillin

B lactam cell wall inhibitor

anti-pseudomonal

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cefazolin

1st gen cephalosporins (Contain FA)

Narrow spectrum; Good activity against gram pos.

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cefuroxime

2nd gen cephs (contain FU)

Intermediate spectrum

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ceftriaxone

3rd gen cephs (Tri)

Broad spectrum; Used for serious gram neg. infections;
Extended spectrum increases risk of secondary infections

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cefepime

4th gen cephs (contain PI)

Broad spectrum; Increased activity against pseudomonas

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ceftaroline

5th gen cephs (contain ROL)

Very broad spectrum; Active against MRSA; Does not cover pseudomonas

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meropenem

B lactam cell wall inhibitor

carbapenems

Increased seizure risk with renal dysfunction
Broad spectrum;
Resistant to most b-lactamases;

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aztreonam

B lactam cell wall inhibitor

monobactams

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clavulanic acid

Binds active site of b-lactamases; Inhibits hydrolysis of b-lactam drugs

Never given alone; Always in combination with b-lactam drug

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vancomycin

Binds D-ala-D-ala of cell wall precursors; Inhibits elongation of peptidoglycan chain

Nephrotoxicity, otoxocity, “Red man syndrome” flushing caused by rapid iv administration

MRSA active, oral for C.diff; Resistance can occur by altered D-ala-D-ala in peptidoglycan

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bacitracin

Prevents dephosphorylation of inactive lipid carrier to active form; Hinders transport of peptidylglucan building block from inside to outside of cell

Nephrotoxicity

Toxicity limits use to topical; Treat minor skin infections

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chloramphenicol

Binds 50S ribosomal subunit; Inhibits peptidyltransferase reaction (peptide transfer) in protein synthesis

Bone marrow depression; Serious and fatal blood disorders

Limited use due to toxicity

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azithromycin

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macrolides

Reversibly binds 50S ribosomal subunit; Blocks translocation of ribosome during protien synthesis

Cholestatic hepatitis; Arrhythmias cause by prolonged QT; GI motility issues

clindamycin

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licoamides

Reversibly binds 50S ribosomal subunit; Inhibits peptidyltransferase reaction (peptide transfer) in protein synthesis

MRSA active

linezolid

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oxazolidinones

Reversibly binds 50S ribosomal subunit; Prevents formation of initiation complex for protein synthesis

Bone marrow suppression; Serotonin syndrome (as MAO inhibitor)

MRSA active

gentamicin

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aminoglycosides

Irreversibly binds 30S ribosomal subunit; Inhibits initiation of protein synthesis; Causes misreading of mRNA

Nephrotoxicity; Ototoxicity

doxycycline

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tetracyclines

Reversibly binds 30S ribosomal subunit; Prevents entry of aminoacyl-tRNA during protein synthesis

GI stress

Some tetracyclines (e.g. doxy. and tigecycline) MRSA active; Doxycycline used to treat malaria

tigecycline

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glycylcyclines

Reversibly binds 30S ribosomal subunit; Prevents entry of aminoacyl-tRNA during protein synthesis

GI stress

Tetracycline derivative

sulfamethoxazole

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Competitive inhibitor of dihydropteroate synthase; Blocks synthesis of dihydrofolic acid

hypersensitivity reactions

Sulfa + trimeth almost always used together; Active against MRSA

trimethoprim

Competitive inhibitor of bacterial DHFR (dihydrofolate reductase) in folate synthesis pathway Bone marrow toxicity; Anemia, leukopenia Sulfa + trimeth almost always used together; Active against MRSA

ciprofloxacin

fluoroquinolones Inhibitor of bacterial DNA gyrase (topo II) & topoisomerase IV, enzymes that unwind DNA; Disrupts bacterial DNA replication & chromosome segregation GI stress, nausea; Tendonitis, tendon rupture in elderly

daptomycin

membrane disrupter Inserts into membranes to create channels; Causes leakage of small ions/molecules Skeletal muscle pain and weakness Inactivated by pulmonary surfactants (not for pneumonia); MRSA active

rifampin

TB drug RNA synthesis inhibitor Bacterial RNA polymerase inhibitor; Binds to beta subunit of RNA polymerase CYP450 inducer; Increases metabolism of other drugs; Hepatotoxicity

isoniazid

TB drug cell wall inhibitor Prodrug activated by mycobacterial KatG encoded catalase peroxidase; Inhibits synthesis of mycolic acid, important structural component unique to mycobacterial cell wall Vitamin B6 deficiency; Hepatotoxicity

pyrazinamide

TB drug Prodrug metabolized by mycobacterial pyrazinamidase to active form pyrazinoic acid; Exact mechanism unknown Hyperuricemia; Hepatotoxicity

ethambutol

TB drug cell wall inhibitor Inhibits arabinosyltransferase EmbB required for synthesis of arabinogalactan, essential component of myocobacterial cell wall Visual disturbances

How do bacteria become resistant to b-lactam antibiotics?

1. Hydrolysis of B-lactam ring 2. Structural changes to transpeptidase 3. Change in porin channels found in outer membrane of Gram neg.

How do bacteria become resistant to cycline antibiotics?

1. Decreased influx or increased efflux | 2. Expression of ribosome protection proteins that interfere with drug-target binding

How do bacteria become resistant to Aminoglycoside antibiotics?

1. Plasmid mediated expression of drug modification: | Acetylation of amine group; Phosphorylation or adenylation of hydroxyl group.

How do bacteria become resistant to Chloroamphenicol antibiotics?

1. Plasmid mediated expression of acetyltransferase that inactivates the drug.

How do bacteria become resistant to Macrolides antibiotics?

1. Efflux pumps | Production of methylase that adds a methyl group to rRNA which prevents drug binding site in ribosome.

How do bacteria become resistant to Linezolid antibiotics?

1. Rare

How do bacteria become resistant to Sulfonamides antibiotics?

1. Decreased intracellular accumulation. 2. Increased PABA production 3. Decreased sensitivity of dihydroteroate synthase

How do bacteria become resistant to Trimethoprim antibiotics?

1. Production of DHFR with reduced affinity for drug.

How do bacteria become resistant to Floroquinolones antibiotics?

1. Active efflux pumps | 2. Point mutation in DNA gyrase or topo 4

How do bacteria become resistant to Rifampin antibiotics?

1. Mutation in B-subunit of RNA pol

How do bacteria become resistant to Isoniazid antibiotics?

1. Mutation on KatG and InhA

How do bacteria become resistant to Pyrazinamide antibiotics?

1. Mutation in PncA

How do bacteria become resistant to Ethambutol antibiotics?

1. Mutation in EmbB

Bacterial Drugs Flashcards

(44 cards)