The "Other Guys" Antibiotics

Question 1

Fluoroquinolones

Answer 1

Ciprofloxacin (Cipro): 200-400mg IV q12h or 250-740mg PO q12h

Levofloxacin (Levaquin): 250-750 mg IV/PO daily

Moxifloxacin (Avelox)

MOA: Inhibits DNA Gyrase (topo II) - for G(-) and Topoisomerase IV for G(+).

Coverage:
G(+): Respiratory Quinolones (Levofloxacin/Moxifloxacin) covers S.pneumo, E. faecalis, and S.viridans

G(-): All enterobacteriaceae, H. flu, M.cat, Neisseria. Cipro > Levo for P. Aeruginosa

Anaerobes: Moxifloxacin

Uses: CAP, UTIs, intra-abdominal infections

ADR: QT prolongation, CNS affects, increased C. diff, Tendonitis/ Tendon rupture (BBW), Dysglycemia (Hypo or Hyper), impaired cartilage formation (avoid in prengnacy)

Pearls: Avoid with multivalent cations, DDI CYP1A2, Levofloxacin/Ciprofloxacin require renal dose adjustment.

Question 2

Nitroimidazoles

Answer 2

Metronidazole (Flagyl): 500mg PO/IV q 6-8h

MOA: produces reactive radicals that cause cell death

Coverage:
Anaerobes: Bacteroides, Clostridium + C.diff, Peptostreptococcus
Parasitic Anaerobe: Trichomonas vaginalis (STD)

Uses: Anaerobic infections (DOC for B. fragilis), brain abscesses, intra-abdominal infections, bacterial vaginosis, trichomoniasis. 1st line for Bacteroides, 2nd line for C.diff

ADR: Metallic taste, Stomatitis, Peripheral neuropathy, Avoid in pregnancy and breastfeeding.

Pearls: Avoid alcohol use (x48 hours after use)

Question 3

Sulfonamides (Antimetabolite)

Answer 3

Trimethoprim/Sulfamethoxazole (Bactrim)

MOA: Inhibits microbial folic acid synthesis cause bactericidal activity.

Coverage:
G(+): CA-MSRA, MSSA
G(-): E. coli, Klebsiella

Uses: SSTI, UTI, PJP/PCP Pneumonia, opportunistic infections/prophylaxis

ADR: Hypersensitivity (Sulfa allergies), photosensitivity, GI, hematologic (G6PD deficient), Avoid in pregnancy

Pearls: needs renal dose adjustment

Question 4

Nitrofurans

Answer 4

Nitrofurantoin (Macrobid, Macrodantin): ER dose: 50-100mg PO q12h

MOA: Blocks translation and inhibits bacterial respiration and metabolism

Coverage:
G(+): S. saprophyticus
G(-): E. coli

Uses: uncomplicated UTI - cystitis (in young women)

ADR: GI (N/V), loss of appetite

Pearls: Contraindicated when CrCl < 30.

Question 5

Fosfomycin

Answer 5

Fosfomycin PO

MOA: Inactivates enzyme used in early step of bacterial peptidoglycan synthesis

Uses: G(-) UTIs (not first line)

ADR: GI (N/V)

Pearls: Safe for pregnant women, often used for UTIs during pregnancy

Question 6

Rifamycins

Answer 6

Rifampin IV/PO
Rifabutin PO
Rifaximin PO

MOA: inhibits RNA polymerase, preventing transcription

Coverage/Use:
Atypical: Mycobacteria
Rifampin: G(+): MSSA/MRSA in synergy
Rifampin/Rifabutin: tuberculosis combination regimens

ADR: Discolored body fluids (orange-red), Hepatotoxicity, Rifampin decreases effectiveness of oral contraceptives (Use Rifabutin instead)

Pearls: Rifampin PO/IV greatly induces 3A4 decreases oral contraceptives effectiveness, use Rifabutin intstead.
Rifaximin is used to kill E.coli

Question 7

Polymyxins

Answer 7

Colistin
Polymyxin B

MOA: displaces calcium and magnesium, causing leakage of intracellular contents due to increased membrane permeability. (bactericidal -concentration dependent)

Coverage: A. baumanii, P. aeruginosa, Klebsiella

Uses: Last-line agents against multidrug-resistant and extensively drug-resistant G(-) pathogens)

Question 8

MRSA agents

Answer 8

CA-MRSA (SSTI):
Bactrim, Clindamycin, Doxycycline, Tedizolid, Oritavancin, Dalbavancin

HA-MRSA: Vancomycin (DOC), Daptomycin (not for pneumonia), Linezolid, Ceftaroline, Televancin, Synervid (avoid use), Tigecycline (last line, CI bacteremia)

Question 9

Enterobacteriaceae

Answer 9

Penicillins: Amino PCNs
Cephalosporin: 1st to 3rd gen
Carbapenem: Any (overkill)
Aztreonam: use (if theres an allergy)

KPC enzymes:
Avycaz, Vabomere, Recarbrio

Question 10

Pseudomonas Aeruginosa

Answer 10

Zosyn, Ceftazidime, Cefepime, Carabapenems (not ertapenem), Aztreonam, Cipro/Levofloxacin, Amikacin > Torbramycin > Gentamicin

Question 11

Enterococcus

Answer 11

Ampicillin ± Gentamicin
Vancomycin ± Gentamicin
Linezolid, Daptomycin, Carbapenems, Tigecycline, Lipoglycopeptides (Vancins)

Question 12

A. baumanii

Answer 12

Carbapenems (50% of strains are resistant)
Polymyxin B and Colistin
High dose Unasyn

Question 13

Atypicals

Answer 13

Macrolides
Tetracyclines
Fluoroquinolones

Question 14

Anaerobes Bacteroides

Answer 14

Metronidazole, BL/BLI combo, carbapenems, Moxifloxacin, Cefoxitin, Cefotetan, Cindamycin

Question 15

Anaerobes Clostridium

Answer 15

PO vancomycin, PO fidoxamicin, PO/IV metronidazole (potentially)

Question 16

No Renal Dose Adjustments

Answer 16

Nafcillin/Oxacillin
Ceftriaxone
Azithromycin

Question 17

Bacteriocidal

Answer 17

β-lactams, Vancomycin, Daptomycin, Quinolones, Aminoglycosides, Polymyxins, Nitrofurantoin, Metronidazole, Fosfomycin

Question 18

Bacteriostatic

Answer 18

Protein synthesis inhibitors except aminoglycosides.

Macrolides, Tetracyclines, Linezolid/Tedizolid, Clindamycin

Question 19

CPJE Outpatient Pearls

Answer 19

All β-lactam suspensions are refrigerated EXCEPT Cefdinir (do not refrigerate), Amoxicillin (refrigeration recommended but room temp is OK)

All other antibacterial suspensions are room temp. EXCEPT Vancomycin

Take antibacterials with food EXCEPT: Pen VK, Levaquin solution, Zithromax ER Suspension, Metronidazole ER, Diclofloxacin, Lefamulin

Question 20

CPJA IV Pearls

Answer 20

NS only: Ertapenem, Daptomycin, Ampicillin, Unasyn

D5W only: Bactrim, Amphotericin B, Synercid

AVOID with Lactated Ringer’s Ca2+ solutions: Ceftriaxone, Zosyn without EDTA

Short stablities: Bactrim, Rifampin

Protect from light: Doxycycline, Rifampin

Question 21

Adverse Events Shared by Classes

Answer 21

Photosensitivity: Bactrim, Tetracyclines, Quinolones

Avoid with multivalent cations: Tetracyclines, Quinolones

Nephrotoxicity: Vancomycin, Aminoglycosides, Polymyxins,

Hypersensitivity reactions: β-lactams (not Aztreonam), Sulfamethoxazole (component of bactrim)

Question 22

Stewardship Prospective Audit and Feedback

Answer 22

Pros:
Visibility of program and potential to build collegial relationships.
More clinical data available.
More flexibility.
Resource flexibility.
Educational benefit for prescribers.
Prescriber autonomy maintained
Adresses de-escalation and DOT

Cons:
Variable success depending on feedback to prescribers.
Labor intensive.
Prescriber compliance is voluntary.
Prescriber reluctance to change therapy if patient is improving.
Technological limitations.
May take more time to decrease antimicrobial use

Question 23

Stewardship Preauthorization

Answer 23

Pros: 
Prevent initiation of certain agents
Optimize empiric therapy.
Direct control over antimicrobial use. 
Decrease antimicrobial costs.
Rapid response to shortages.
Encourage a more thorough review of available clinical data.

Cons: 
Only impacts restricted agents
Downstream use neglected.
Shift to other agents
Loss of prescriber autonomy
May delay therapy
Approver skill impact effectiveness.
Resource intensive