Clinical Use of Antimicrobials

Question 1

Drugs for Gram + bugs

Answer 1

PCN G and V, Anti-staph PCN, 1st gen cephalosporins, Vancomycin, Daptomycin, Bacitracin, Streptogramins

Question 2

Drugs for Gram- bugs

Answer 2

Anti pseudomonal PCN, Aztreonam, 2nd gen Cephalosporins

Question 3

Renal Elimination

Answer 3

Aminoglycosides, most cephalosporins, Flouroquinolones, PCN, Sulfonamides, Tetracyclines, TMP-SMX, Vancomycin

Question 4

Hepatic Elimination

Answer 4

Chloramphenicol, clindamycin, erythromycin, clarithromycin, Nafcillin

Question 5

Aerobic only

Answer 5

Aztreonam, Aminoglycosides

Question 6

Anaerobic

Answer 6

Metronidazole

Question 7

Bactericidal

Answer 7

Aminoglycosides, B-lactams, Fluoroquinolones, metronidazole, vancomycin, Streptogramins

Question 8

Bacteriostatic

Answer 8

Clindamycin, macrolides, sulfonamides, tetracyclines, trimethoprim

Question 9

Effects on Fetus and neonate

Answer 9

Aminoglycosides: damage to 8th Cranial nerve
Tetracylcines/glycyclines: tooth enamel dysplasia and inhibition of bone growth
Sulfonamides: Kernicterus
Chloramphenicol: Gray baby syndrome (aplastic anemia)
Fluoroquinolones: cartilage damage
Nitrofurantoin: Hemolytic anemia
Trimethoprim: folate deficiency
Clarithromycin: embryonic

Question 10

Surgical Prophylaxis

Answer 10

Important for procedures with a history of >50% infection without treatment (GI, Hysterectomy, C-section, Joint replacement, Open fracture surgery)
-Most situations use Cefazolin
-with MRSA in Cardiothoracic surgery add Vancomycin
-colorectal: use ampicillin and sulbactam
For patients with PCN allergies: cardiothoracic changes to vancomycin + Azreonam and for colorectal use ciprofloxacin + metronidazole or clyndamycin

Question 11

Clostridium Difficile colitis

Answer 11

Common Causes: Clindamycin
*also ampicillin, amoxicillin, cephalosporins, fluoroquinolones
DOC: Oral Metronidazole, vancomycin, Fidaxomicin (decrease recurrence)

Question 12

Bacterial Meningitis in Adults

Answer 12

Empiric Treatment in all clinical settings in Vancomycin + Ceftriaxone (3rd gen)
Prophylaxis: Rifampin, Cipro, Ceftriaxone
Community: Use PCN G or ceftriaxone for S pneumonia or N meningitidis, for H inf: Ceftriaxone
Post-traumatic/surgical: S epidermidis: vancomycin
S Aureus: Oxacillin
P Aeruginosa: Ceftazidime + gentamycin
Immunocompromised: Listeria: Ampicillin + gentamycin
P Aeruginsoa: Ceftazidime + gentamycin
S Pneumonia: Vancomycin + 3rd gen cephalosporin

Question 13

Treatment of MDR infection

Answer 13

Anti Staph PCN: B lactamase producing gram +
Carbapenems: B lacatamase producing gram +/-
Aztreonams: B lactamase producing gram -
Vancomycin: MRSA and enterococci
Daptomycin: MRSA, enterococci and VRE
Tigecycline: MDR gram + and some gram-
Streptogramins: MRSA and VRE
Linezolid:MRSA and VRE
Rifampin: MTB, MRSA, meningitis prophylaxis
Start low and move up

Question 14

Endocarditis Prophylaxis

Answer 14

Most common during dental or respiratory procedures
Standard: oral amoxacillin
PCN allergy: Clindamycin, cephazolin, or macrolide
IV or IM meds: Ampicillin or if allergic to PCN use clindamycin or cefazolin

Question 15

Syphilis and UTI’s in Pregnancy

Answer 15

DOC for syphilis not matter what the stage in PCN G and is the only drug with documented efficacy during pregnancy.

• If a pregnant patient is allergic to PCN G, She should undergo desensitization rather than use any other drug.
• May develop a Jarisch-Herxheimer reaction: Fever, chills, myalgia, tachycardia…It is not an allergic reaction and the drug should be continued (Pretreatment with prednisolone may help)
• UTI Tx(Ecoli): Cotrimoxazole, Cipro, Nitofurantion or amoxicillin and clavulanic acid
• Pregnant and have UTI: PCN or cephalosporin (however, ceftriaxone can cause kernicterus) or nitrofurantoin.

Question 16

Community Acquired PNA

Answer 16

Most often caused by S Pneumonia
Atypical Pathogens include: Mycoplasma, legionella, chlamydia
*Macrolides/Doxycycline for healthy pt without antimicrobial use in past 3 months
*Fluoroquinolones or B lactam+Macrolide:for comorbidities or recent use of antimicrobial or inpatient, nonICU.
For patients who are allergic to PCN: fluoroquinolones and azetreonam

Question 17

Infective Endocarditis

Answer 17

*this is abnormal HV and bacteremia. **Need to have 3 separate cultures
Native valve (S viridans/bovis): PCN G or ceftriaxone+gentamycin)
Native valve (Staph): nafcillin or oxacillin, if they have a PCN allergy use cefazolin or if resistant use vancomycin
Prosthetic valve: Vancomycin+gentamycin +/- rifampin. If resistant to Vanc use Linezolid or daptomycin can be used