Term
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Definition
Efflux pumps remove the drug from the bacteria.
They can be non-specific or specific.
They can be intrinsic, acquired, or mutational (derepression of pump expression). |
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Term
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Definition
| Gram-negative and Gram-positive bacteria produce -lactamases that will inactive penicillin by cleaving the -lactam ring. |
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Term
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Definition
| Fosfomycin is cleaved by fosfomycinases |
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Term
| Modification of aminoglycosides/chloramphenicol |
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Definition
Aminoglycosides are inactivated by modification by the bacteria. There are 3 basic modifications that will inactivate Aminoglycosides:
1. N-acetylation
2. O-phosphorylation
3. O-adenylation
Chloramphenicol can be inactivated by acetylation (acetyl transferase) |
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Term
| Target site modifications - PBP |
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Definition
Target site modifications will prevent antibiotic action. These include mutation to specific targets that are either acquired or mutational.
MRSA (methicillin resistant S. aureus)
mecA gene encodes a new beta-lactam resistance PBP (PBP2a)
S. pnuemoniae
PBP2X – low level resistance
PBP2B – low and high level resistance |
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Term
| Target site modification - Methylation of 23s rRNA |
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Definition
| MLS (macrolide-lincosamide-streptogramin) strains have a erthromycin methyltransferase gene that methylates 23S rRNA prevent interaction of macrolides and lincosamides/clindamycin with the 23S rRNA and the 50S ribosomal subunit |
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Term
| Target site modification - Vancomycin resistance |
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Definition
| Vancomycin resistance is acquired and encoded by 7 genes. These genes change the D-Ala-D-Ala pentapeptide to D-Ala-D-Ser or D-Ala-D-Lac. There are 3 types of Vancomycin resistance operons: VanA, VanB, VanC. |
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Term
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Definition
| There are either modification or complete substitution of Dihydropteroic acid synthetase and Dihydrofolate reductase |
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