ANTIBIOTICS Flashcards
Penicillins moa
• Inhibit bacterial cell wall synthesis by blocking the transpeptidation step1
Cephalosporins moa
• Structure resembles the penicillins, possessing a β-lactam ring
• Block bacterial cell wall synthesis through inhibition of penicillin-binding proteins that
catalyze transpeptidation
Penicillins
Cephalosporins
Tetracyclines
A beta-hemolytic streptococci,
Neisseria species, Treponema pallidum, and Erysipelothrix rhusiopathae
staphylococci and nonenterococcal
streptococci4
Effective against both gram-positive and negative organisms, mycoplasma infections,
Chlamydia and Rickettsia infections
Tetracyclines moa
Inhibit protein synthesis by binding to the 30S ribosomal subunit
tetracycline, unlike minocycline and doxycycline
impaired by the ingestion
of dairy products, calcium, and iron or zinc salts
only tetracycline for use in patients with renal
failure
Doxycycline, excreted by the GI tract
most phototoxic of all the tetracyclines
Demeclocycline and doxycycline
Tetracyclines are contraindicated
less than 9 years
of age → risk of brown discoloration of the teeth and delayed
bone growtha brown discoloration along the gingival third
allergic to penicillins may also exhibit similar
allergic reactions to cephalosporins
10% of patients
Tetracyclines ADR
Pneumonitis, drug-induced lupus and serum
sickness-like reactions from tetracyclines have been reported
most common
cause of fixed drug eruption
Tetracycline:
minocycline stains the permanent teeth in
adults,
with a gray-green discoloration of the midportion of the tooth
increased incidence of
serum sickness in children
Cefaclor
Inhibit the 50S ribosomal subunit during protein synthesis
MACROLIDE
gram-negative soft-tissue infections
Azithromycin and clarithromycin
cne, pyodermas, erythrasma,
and pitted keratolysis
Erythromycin
Cholestatic hepatitis is associated
with the ? form of
erythromycin12
estolate
inhibiting the cytochrome P-450
• Erythromycin
increasing levels of carbamezapine, warfarin, theophylline, phenytoin, digoxin, and
terfenadine
Fluoroquinolones
• Inhibit DNA gyrase
Mycobacterium species, gram-negative infections, particularly
Enterobacteriaceae organisms and multiresistant bacteria
Fluoroquinolones
Antacids ? the absorption of fluoroquinolones and should be taken at least two
hours after the drug
decrease
Rifampin
inhibits RNA synthesis by inhibiting DNA-dependent RNA polymerase
Only drug bactericidal to M. leprae
Effective in tuberculosis and atypical mycobacterial infections
Cutaneous leishmaniasis and rhinoscleroma
Rifampin
orange-red discoloration
Rifampin
Clindamycin MOA
• Binds to the 50S ribosomal subunit and inhibits protein
synthesis
deep tissue infections anaerobic and gram-positive organisms
Clindamycin
Pseudomembraneous colitis associated with Clostridium difficile
10% of treated patients Clindamycin
