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3.1 Flashcards

Antibiotics

1
Q

selective toxicity

A

targeting differences in cell structure or morphology, resulting in destruction of bacterial cells but not host cells

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2
Q

ideal chemotherapeutic agent

A

no allergy, no resistance, and selective toxicity (just against microbe)

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3
Q

what is selective toxicity measured by?

A

chemotherapeutic index (want very forgiving drug)

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4
Q

broad spectrum

A

less discrimination and targets a wide range of organisms

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5
Q

narrow spectrum

A

only targets a select group while leaving others unharmed; unlikely resistance will develop due to limited use

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6
Q

Cell Wall Synthesis Inhibitors

A

Beta-lactams, Glycopeptides, Polypeptides, Acid-fast drugs

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7
Q

Transpeptidase

A

Penicillin Binding Protein; synthesizes the cross link; w/o this, integrity of cell wall will fall apart

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8
Q

Beta-lactam antibiotics

A

competitively bind to transpeptidase and prevent peptidoglycan crosslinking

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9
Q

Penicillin

A

Beta-lactam
- inhibits transpeptidase, but susceptible to beta-lactamase
- ex: Penicillin G and V
- Spectrum: G+, select G-

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10
Q

Beta-lactamase

A

enzymes that bind to beta-lactam antibiotics and destroy them; led to creation of semi-synthetic penicillin

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11
Q

Semi-synthetic penicillin

A

Beta-lactam
1. Ex: Methicillin, Oxacillin
Spectrum: G+
Increases resistance to
beta-lactamase
2. Ex: Piperacillin,
Temocillin
Spectrum: G-
3. Ex: Amoxicillin,
Ampicillin
Spectrum: Broad
Often combined with
beta-lactamase
inhibitor; most
prescribed antibiotics in
USA

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12
Q

clavulanic acid

A

binds and inhibits beta-lactamases

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13
Q

Cephalosporins

A

Beta-lactam
1st gen: G+, select G-
2nd gen: G+, increased G-
3rd gen: G+, most G-
4th gen: Broad
- Cefepime
5th gen: MRSA treatment
- Ceftaroline
*More resistant to beta-lactamases, less likely to produce allergy than penicillin, can lead to C. diff, top most prescribed antibiotics in USA

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14
Q

Monobactam

A

Beta-lactam
Ex: Aztreonma
Spectrum: Aerobic gram-negative
* Resistant to beta-lactamase, can be nebulized to treat lung infections

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15
Q

Carbapenem

A

Beta-lactam
Ex: Imipenem, Meropenem
Spectrum: Broad
*Less susceptible to bacterial resistance mechanisms but can be toxic to host, reserved for drug-resistant pathogens

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16
Q

Glycopeptides

A

Ex: Vancomycin, Dalbavancin
Mechanism: Blocks transpeptidase and trans glycosylases from creating NAG-NAM synthesis
Spectrum: G+
* useful against MRSA and C.diff, can be more toxic than other cell wall inhibitors

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17
Q

Bacitracin

A

Polypeptide
Mechanism: blocks bactoprenol
Spectrum: G+
* topical antibiotic creams

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18
Q

Acid-fast drugs (CW)

A

Isoniazid
- interferes with synthesis of mycolic acid
Ethambutol
- interferes with synthesis of arabinogalactan
Cycloserine
- interferes with formation of peptidoglycan sidechain formation
*Spectrum: TB
*Can be used for kidney and bladder infections

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19
Q

Cell Membrane Inhibitors

A

Polypeptides, Ionophores, Bacteriocins, Acid-fast drugs

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20
Q

Polymyxins

A

Polypeptide
Ex: B and E (Colistin)
Mechanism: disrupt the membrane and increase permeability, causing cell lysis
Spectrum: G-
* B often found in topical antibiotic creams, E is considered “last-resort”`

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21
Q

Ionophores

A

Gramicidin
Mechanism: forms pores in bacterial membrane
Spectrum: G+
* exists as mixture of gramicidin A/B/C, often used in cough drops, topical creams, eye drops

22
Q

Bacteriocins

A

Nisin
Mechanism: combines with Lipid 2 to form pores in membrane
Spectrum: G+, endospores
* used as food preservative and selective agent in microbiological media

23
Q

Acid-fast drugs (CM)

A

Pyrazinamide
Mechanism: diffuse into cells and enzyme converts to acid, causing physiological changes
Spectrum: TB

24
Q

Protein Synthesis Inhibitors

A

Oxazolidinones, Aminoglycosides, Tetracyclines, Macrolides, Lincosamides

25
No specific class
Chloramphenicol, Mupirocin, Streptogramin
26
peptidyl transferase
blocks peptide bond formation
27
large subunit (50S)
peptidyl transferase activity
28
small subunit (30S)
binds mRNA
29
Oxazolidinones
Ex: -zolid Mechanism: binds to 23S rRNA of 50S (large) subunit and prevents initiation of ribosomal assembly Spectrum: G+ * substitute treatment for drug-resistant S. aureus
30
Aminoglycosides
Ex: Amikacin, Neomycin, Streptomycin Mechanism: irreversible binding to 30S (small) subunit that prevents translation Spectrum: Aerobic G- * renal and CNS side effects; give as IV, IM, or topical cream
31
Tetracyclines
Ex: -cycline; Doxycycline, Tetracycline Mechanism: binds to 30S (small) unit and inhibit tRNA Spectrum: Broad, cell wall-less, some parasitic infections * liver/renal toxicity, effective against rare infections, treat severe acne, top 4 most prescribed antibiotics in USA
32
Macrolides
Ex: Azithromycin (Z-pack), Clarithromycin, Erythromycin Mechanism: bind to 23S rRNA in 50S (large) subunit; inhibit peptidyl transferase and translocation Spectrum: Broad, cell wall-less, some fungal/parasitic infections * topical forms exist, can treat COPD, top 4 most prescribed antibiotics in USA
33
Lincosamides
Ex: Clindamycin, Lincomycin Mechanism: bind to 23S rRNA of 50S (large) subunit and prevent translocation Spectrum: Most G+, anaerobic G- * increased risk of C. diff
34
Chloramphenicol
Mechanism: bind to 23S rRNA in 50S subunit and prevent peptidyl transferase Spectrum: Broad * severe side effects, many drug interactions, used in eye drops but rarely preferred IV/orally over safer drugs
35
Mupirocin
Mechanism: bind to tRNA and prevents amino acid incorporation into polypeptide chain Spectrum: G+ * topical antibiotic, treat MRSA
36
Streptogramin
Combination drug (Dalfopristin and Quinupristin) Mechanism: bind to 50S (large) subunit and prevent elongation Spectrum: Broad * effective against vancomycin resistant organisms, bacteriostatic individually but bactericidal when together
37
Nucleic Acid Synthesis Inhibitors
Quinolones, Nitrofurans, Nitroimidazoles, Acid-fast Drugs
38
DNA Gyrase and Topoisomerase
relieving tension during DNA replication and breaking apart replicated chromosomes after DNA replication
39
Quinolones
Ex: -floxacin Mechanism: target both enzymes, prevent replication and transcription Spectrum: Broad, cell wall-less * Risk for C. diff, rarely given to immunocompromised or children
40
Nitrofuran
Ex: Nitro... and Furazolidone Mechanism: converted within cell to damage DNA Spectrum: Broad * excreted by kidneys, builds up in urine (good for UTIs), not recommended for those with renal issues
41
Nitroimidazoles
Ex: -dazole Mechanism: produce ROS that damage RNA, depletes thiol --> prevents transcription Spectrum: Anaerobic bacteria, some parasitic infection
42
Acid-fast category of Nitroimidazoles
Ex: -manid Mechanism: produce ROS that disrupt formation of arabinogalactan Spectrum: MDR-TB
43
Acid-fast Drugs (NA)
Clofazimine - Spectrum: Leprosy and M. avium - Mechanism: bind to guanine, forms knot and polymerase can't move Rifamycin - Ex: Rifa... - Spectrum: Acid-fast - Mechanism: bind to RNA Polymerase; prevents transcription *Subgroup of Ansamycins, can treat G+/- infections
44
Metabolite Inhibitors
Antifolates and Acid-fast Drugs
45
Tetrahydrofolate (THF)
need for nucleotides, amino acids; selective toxicity because humans don't use pathway; drugs that target this pathway are antifolates 1. PABA, 2. Dihydropteroate Synthetase, 3. Dihydrofolate Reductase
46
Sulfonamides
Antifolate Ex: Sulfa... Mechanism: inhibits Dihydropteroate Synthetase Spectrum: Broad, C. albicans * Earliest antibiotics discovered, highest risks, combined with other drugs for parasitic infections
47
Trimethoprim
Antifolate Mechanism: inhibits Dihydrofolate Reductase Spectrum: Aerobic bacteria * Both antifolates are given together to navigate mutation or rerouting
48
Dapsone
Acid-fast Mechanism: inhibits first enzyme (like Sulfo) Spectrum: Leprosy * anti-inflammatory properties
49
Bedaquiline
Mechanism: blocks ATP synthase by not allowing it to turn (**Shot glass incident) Spectrum: TB * treat MDR-TB
50
Top 4 most prescribed antibiotics
Semi-synthetic Penicillin, Cephalosporins, Macrolides, Tetracyclines
51
Anaerobic bacteria
Clostridium, Chlamydia, Spirochetes

Microbiology (7 decks)

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