Antibacterials 6 Flashcards

1
Q

Describe Cotrimoxazole? MOA?

A
  • Combination of trimethoprim & sulfamethoxazole
  • Bactericidal

Mechanism of action:
• Synergistic: inhibition of sequential steps in
tetrahydrofolic acid synthesis

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2
Q

Cotrimoxazole Clinical Applications?

A

• Uncomplicated UTI’s (drug of choice)
• Commonly used in treatment of opportunistic
infections (in immunocompromised)
• Upper respiratory, ear and sinus infections

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3
Q

Cotrimoxazole PK?

A
  • Oral admin. generally (can be given IV)

* Well distributed (including CSF)

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4
Q

Cotrimoxazole AE?

A
  • Dermatologic (common)
  • GI
  • Hematologic (hemolytic anemia)
  • AIDS patients = higher incidence
  • Contraindicated in pregnancy (esp. 1st trimester)
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5
Q

Describe Metronidazole

A
  • Antimicrobial, amebicide & antiprotozoal
  • Activity against anaerobic bacteria
  • Bactericidal
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6
Q

Metronidazole MOA?

A

• Anaerobic conditions are vital for optimal activity
• Undergoes reductive bioactivation of its nitro group by
ferredoxin
• Forms cytotoxic products that interfere with nucleic acid
synthesis -> damage DNA

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7
Q

Metronidazole Clinical Applications?

A
  • Pseudomembranous colitis
  • Anaerobic or mixed intra-abdominal infections
  • Vaginitis
  • Brain abscesses
  • H.pylori eradication (in combination)
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8
Q

Metronidazole PK?

A
  • Oral, IV, rectal or topical
  • Wide distribution (including CSF)
  • Elimination = hepatic metabolism
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9
Q

Metronidazole AE?

A

• Disulfiram-like effect (avoid alcohol)
• Headache, dark coloration of urine, metallic taste
• GI irritation, stomatitis, peripheral neuropathy (prolonged
use)
• Leukopenia, dizziness, ataxia (rarer)
• Opportunistic fungal infections
• Use generally not advised in 1st trimester

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10
Q

Describe Polymyxin B?

A
  • Basic peptides
  • Activity against Gram-negative bacteria
  • Gram-positive bacteria are resistant
  • Bactericidal
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11
Q

MOA of Polymyxin B?

A
  • Act as cationic detergents
  • Attach to and disrupt bacterial cell membranes
  • Also, bind to and inactivate endotoxin
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12
Q

Polymyxin B Clinical Applications?

A

• Mostly topical treatment for infected superficial skin
lesions
• Possible emerging role as parenteral agent for salvage
therapy of infections caused by resistant Acinetobacter
baumannii, P.aeruginosa and Enterobacteriaceae strains

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13
Q

Polymyxin AE?

A
  • Few when used topically

* Given systemically = extremely nephrotoxic

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14
Q

Describe Urinary antiseptics and use?

A
  • Oral agents with antibacterial activity in urine but little or no systemic effect
  • Use is limited to prophylaxis and treatment of lower UTI’s
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15
Q

Describe Nitrofurantoin?

A

• Bacteriostatic & bactericidal
• Active against many Gram-positive and Gram-negative
bacteria

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16
Q

Nitrofurantoin MOA?

A

• Reduction of nitrofurantoin by bacteria in the urine leads
to formation of reactive intermediates that subsequently
damage bacterial DNA
• Slow emergence of resistance and no cross-resistance

17
Q

Nitrofurantoin PK and AE?

A

Pharmacokinetics
• Rapid elimination (only achieves adequate concentrations
in urine)

Adverse Effects
• Anorexia, nausea & vomiting.
•Neuropathies, hemolytic anemia (G6PD deficient patients)
•Pulmonary injury (rare)

18
Q

Nitrofurantoin Contraindications?

A
  • Significant renal insufficiency
  • Pregnancy at term (38-42 weeks)
  • Infants <1 month (risk of hemolytic anemia)
19
Q

Antimicrobial effect on fetus and neonate? Aminoglycoside? Tetracycline,Glycilines? Sulfonamides? Choramphenicol? Fluoroquinolones? Nitrofurantion? Trimethoprim? Metronidazole?

A

Aminoglycosides -Possible damage to the eighth
cranial nerve of the fetus

Tetracyclines, Glycylcyclines -Tooth enamel dysplasia, inhibition
of bone growth

Sulfonamides Kernicterus (displacement of
bilirubin from serum albumin)

Chloramphenicol Gray baby syndrome

Fluoroquinolones Tendon rupture/damage

Nitrofurantion Hemolytic Anemia

Trimethoprim Folate deficiency

Metronidazole Unknown safety

20
Q

Surgical Antimicrobial Prophylaxis Cardiothoracic?

A

Antimicrobials:
Routine: Cefazolin
MRSA: Cefazolin +
vancomycin

Penicillin-allergic patient:
Vancomycin + aztreonam (routine & MRSA)

21
Q

Surgical Antimicrobial Prophylaxis Colorectal?

A

Antimicrobials:
Ampicillin/sulbactam

Penicillin-allergic patient:
Ciprofloxacin +
metronidazole or
ciprofloxacin +
clindamycin
22
Q

Surgical Antimicrobial Prophylaxis General Surgery?

A

Antimicrobials: Cefazolin

Penicillin-allergic patient:
Vancomycin or
clindamycin

23
Q

Surgical Antimicrobial Prophylaxis Neurosurgical?

A

Antimicrobials: Cefazolin

Penicillin-allergic patient: Vancomycin

24
Q

Surgical Antimicrobial Prophylaxis Orthopedics?

A

Antimicrobials: Cefazolin

Penicillin-allergic patient:
Vancomycin or
clindamycin

25
Q

Surgical Antimicrobial Prophylaxis Vascular Surgery?

A

Antimicrobials: Cefazolin or cefuroxime

Penicillin-allergic patient:
Vancomycin or
clindamycin

26
Q

Anti-staphylococcal penicillins used against which bacteria?

A

beta-lactamase producing bacteria

Gram +ve

27
Q

Carbapenems used against which bacteria?

A

beta-lactamase producing bacteria

Gram +ve and –ve

28
Q

Aztreonam used against which bacteria?

A

beta-lactamase producing bacteria

Gram –ve

29
Q

Vancomycin used against which bacteria?

A

MRSA, enterococci

30
Q

Daptomycin used against which bacteria?

A

MRSA, enterococci, VRE

31
Q

Tigecycline used against which bacteria?

A

MDR Gram +ve and some Gram –ve bacteria

32
Q

Streptogramins used against which bacteria?

A

MRSA, VRE

33
Q

Linezolid used against which bacteria?

A

MRSA, VRE

34
Q

Rifampin used against which bacteria?

A

MRSA