Antibiotics Flashcards

1
Q

What is the structure of Gram (+) bacteria?

A

Thick peptidoglycan layer, contains teichoic acid, no outer membrane, stains purple.

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2
Q

What is the structure of Gram (-) bacteria?

A

Thin peptidoglycan layer, outer membrane with lipopolysaccharides (LPS), contains porins, stains pink.

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3
Q

What are the five general properties of antimicrobial agents?

A

Solubility in body fluids, selective toxicity, stability and resistance to degradation, spectrum of activity, limited side effects.

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4
Q

Name three Gram (+) bacteria and the diseases they cause.

A

Staphylococcus aureus: skin infections.
Streptococcus pyogenes: strep throat.
Clostridium difficile: pseudomembranous colitis.

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5
Q

Name three Gram (-) bacteria and the diseases they cause.

A

Escherichia coli: UTIs.
Pseudomonas aeruginosa: hospital-acquired infections.
Neisseria gonorrhoeae: gonorrhea.

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6
Q

Name three atypical bacteria and the diseases they cause.

A

Mycoplasma pneumoniae: atypical pneumonia.
Chlamydia trachomatis: STIs.
Rickettsia spp.: Rocky Mountain spotted fever.

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7
Q

What is the spectrum of activity of antibiotics?

A

The range of pathogens an antibiotic can target (narrow vs. broad-spectrum).

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8
Q

What is selective toxicity in antibiotics?

A

The ability to target bacterial processes without harming host cells.

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9
Q

What are the five main targets of antimicrobial agents?

A

Cell wall synthesis: penicillins, cephalosporins.
Cell membrane: polymyxins.
Protein synthesis: tetracyclines, macrolides.
Nucleic acid synthesis: fluoroquinolones.
Folic acid synthesis: sulfonamides, trimethoprim.

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10
Q

How do beta-lactam antibiotics kill bacteria?

A

Inhibit transpeptidase enzymes, preventing peptidoglycan cross-linking, leading to bacterial lysis.

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11
Q

What are three mechanisms of beta-lactam resistance?

A

Beta-lactamases hydrolyze the beta-lactam ring.
Altered penicillin-binding proteins (PBPs).
Decreased permeability via porin mutations in Gram (-) bacteria.

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12
Q

What are examples of penicillins and their uses?

A

Penicillin G: narrow-spectrum, Gram (+), used for strep, C-diff, meningitis.

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13
Q

What are examples of cephalosporins and their uses?

A

Cephalexin: first-generation, Gram (+), used for skin infections and UTIs.

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14
Q

What are examples of carbapenems and their uses?

A

Imipenem: broad-spectrum, used for serious hospital-acquired infections, sepsis, and pneumonia.

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15
Q

What are examples of monobactams and their uses?

A

Aztreonam: Gram (-), used for UTIs, lower respiratory tract infections, and Gram (-) sepsis.

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16
Q

What are the major adverse effects of penicillins?

A

Allergic reactions, GI upset, interstitial nephritis.

17
Q

What are the major adverse effects of cephalosporins?

A

Hypersensitivity, bleeding disorders, superinfections.

18
Q

What is a key feature of imipenem, and how is it used?

A

Broad-spectrum, co-administered with cilastatin to prevent renal degradation.

19
Q

What is a benefit of meropenem over imipenem?

A

Similar broad-spectrum activity but less nephrotoxic.

20
Q

Why is premature termination of antibiotics problematic?

A

Encourages resistance, leading to infection relapse or persistence.

21
Q

What are the clinical uses of vancomycin?

A

Treats MRSA and penicillin-resistant Gram (+) infections.

22
Q

What are the toxicities of vancomycin?

A

Red man syndrome, nephrotoxicity, ototoxicity.

23
Q

How do polymyxins work, and what bacteria do they target?

A

Bind bacterial membrane phospholipids, disrupting integrity, targeting Gram (-) bacteria.

24
Q

Why are protein synthesis inhibitors broad-spectrum?

A

They target bacterial ribosomes (70S), which differ from human ribosomes (80S).

25
Q

What are the toxicities of tetracyclines?

A

DEVILS CAP: Dentition issues, epigastric pain, severe nausea/vomiting/diarrhea, vestibular toxicity, liver damage, kidney damage, superinfection, phototoxicity.

26
Q

What are examples of tetracyclines?

A

Doxycycline, tetracycline.

27
Q

What are examples of macrolides?

A

Azithromycin, erythromycin.

28
Q

What are examples of other protein synthesis inhibitors?

A

Clindamycin, linezolid.

29
Q

How do sulfonamides affect bacterial folic acid synthesis?

A

Inhibit dihydropteroate synthase.

30
Q

How does trimethoprim affect bacterial folic acid synthesis?

A

Inhibits dihydrofolate reductase.

31
Q

What are the clinical uses of sulfonamides and trimethoprim?

A

UTIs, pneumocystis pneumonia, toxoplasmosis.

32
Q

How do fluoroquinolones inhibit bacterial nucleic acid synthesis?

A

Inhibit DNA gyrase and topoisomerase IV, preventing DNA replication and transcription.

33
Q

What are problems caused by disruption of normal microflora?

A

Superinfections (e.g., C-diff colitis), yeast infections, reduced pathogen competition.

34
Q

What questions should guide antibiotic selection?

A

Clinical diagnosis, causative organism, antimicrobial susceptibility, spectrum, patient-specific factors.