Other antibiotics

Question 1

Quinolones inhibit:

Answer 1

• DNA gyrase • Topoisomerase IV

Question 2

4 Quinolones end in_

Answer 2

Ciprofloxacin, Levofloxacin, Moxifloxacin, Norfloxacin

Question 3

Quinolones Resistance Mechanisms:

Answer 3

Alterations of DNA gyrase and topoisomerase IV • Alteration in cell permeability • Efflux of drug

Question 4

3 Common clinical uses (adults only) of Quinolones:

Answer 4

Common clinical uses (adults only)

UTIs (E. Coli, other enteric gram negatives)

Pneumonia (S. pneumo, H. flu, atypicals)

Abdominal infections (enteric gram negatives)

Question 5

Quinolones Early Drugs

Answer 5

Nalidixic acid (not a fluoroquinolone), Norfloxacin • Mostly gram negative coverage • Limited/no gram positive coverage

Question 6

Quinolones Ciprofloxacin:

Answer 6

• Some gram positive coverage • Rarely used alone for gram positive coverage (resistance)

Very good gram negative coverage

Most reliable pseudomonas coverage

Used in UTIs, GI infections • Cipro ear drops for otitis externa

Question 7

Quinolones Levofloxacin:

commonly used in:

Answer 7

• More gram positive/atypical coverage than Cipro • Better strep pneumo coverage than Cipro • Covers most methicillin-susceptible Staph aureus • Less effective against pseudomonas than Cipro • Commonly used in pneumonia (strep, atypicals)

Question 8

Quinolones Gatifloxacin, Sparfloxacin, Moxifloxacin

Answer 8

• Better gram (+)/atypical coverage than Levofloxacin • Less effective for pseudomonas than Levofloxacin • Also used in pneumonia

Question 9

Quinolones Adverse Reactions:

rare/serious complication:

Answer 9

generally well tolerated but: Gastrointestinal upset • Anorexia, nausea, vomiting, and abdominal discomfort • Up to 17% of patients • Neurologic side effects • Headache, dizziness • 2 to 6% of patients

QT prolongation on EKG • Caused by blockade of K+ channels • Can lead to torsade de pointes

Question 10

Quinolones Adverse Reactions why can’t be used in kids/pregnancy?

Answer 10

Cannot use in pregnancy/children • Toxic to developing cartilage in animal studies

Tendon rupture/tendonitis • Most commonly Achilles • More common older patients (>60), people on steroids

Question 11

Antacids • Disrupt absorption of many drugs including:

Answer 11

• Key drugs • Tetracycline • Fluoroquinolones • Isoniazid • Iron supplements

Question 12

Vancomycin MOA:

contrast with beta lactams:

Answer 12

• Inhibits peptidoglycan formation (cell wall)

Binds D-alanyl-D-alanine peptides • Prevents crosslinking • Cell wall breakdown>formation → cell death

Same effect as beta lactams via different mechanism • Beta lactams: inhibit transpeptidases • Vancomycin: block transpeptidase binding

Question 13

Vancomycin Resistance:

Answer 13

terminal amino acids change • D-alanyl-D-alanine changed to D-alanyl-D-lactate • VRSA emerges

Question 14

Vancomycin only effective in:

Answer 14

gram (+) • Too large to pass outer membrane gram negatives

Question 15

Two common uses: of Vancomycin:

Answer 15

2: Oral therapy for C. difficile pseudomembranous colitis

• #1: Methicillin resistant Staph Aureus (MRSA)

Often given empirically when MRSA is a concern • Endocarditis • Severe pneumonia/sepsis

Question 16

Vancomycin Adverse Effects

Answer 16

Nephrotoxicity • Less common with modern preparations • Increased risk if concomitant aminoglycoside therapy

Ototoxicity • Tinnitus, vertigo, and hearing loss reported (rare)

• Vancomycin infusion reaction • Flushing, erythema, itching • Usually affects upper body, neck, face more than lower body • Occurs 10-20 minutes after start of infusion • Direct activation of mast cells → histamine release • “Pseudoallergic drug reaction” • May develop with first administration

Infusion related → slow infusion = no symptoms

Question 17

Metronidazole: whats needed for activation?

Answer 17

Prodrug: Must be reduced to activate

Only anaerobic bacteria capable of reduction

Activated form generates free radicals • Interact with DNA • DNA breakage/destabilization • Cell death

Question 18

Metronidazole Uses

Answer 18

• Good coverage of anaerobes “below the diaphragm”

Bacteroides fragilis • Clostridium difficile

Peritonitis, abdominal abscesses, diverticulitis

Often given with quinolone for anaerobic/GI gram(-) • Cipro/Flagyl often used for diverticulitis

Question 19

2 main Metronidazole Uses

Answer 19

• H. pylori and Gardnerella vaginalis • Facultative anaerobic bacteria • Susceptible to metronidazole • Triple therapy for H. Pylori • Treatment of bacterial vaginitis

Question 20

Anaerobic protozoa covered by Metronidazole

Answer 20

Anaerobic protozoa (lack mitochondria) • Trichomonas vaginalis • Entamoeba histolytica • Giardia lamblia

Question 21

Metronidazole Adverse Reactions

Answer 21

Unpleasant metallic taste • GI: Abdominal discomfort, nausea • Neuro: Neuropathy, headache

Disulfiram-like reaction Patients should avoid alcohol

Question 22

whats Used for UTIs in pregnancy? & 3 things to know about it

Answer 22

Nitrofurantoin

• Bactericidal drug
• Only use is UTIs (concentrates in urine)
• Can trigger hemolysis in G6PD patients