Macrolides and ketolides are antibiotics that inhibit bacterial protein synthesis Synthesis Polymerase Chain Reaction (PCR) by binding to the 50S ribosomal subunit and blocking transpeptidation Transpeptidation Lincosamides. These antibiotics have a broad spectrum of antimicrobial activity but are best known for their coverage of atypical microorganisms. Common macrolides are erythromycin, clarithromycin, and azithromycin. Side effects include GI upset, QT prolongation, and hepatotoxicity Hepatotoxicity Acetaminophen. Resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing mechanisms include ribosomal methylation Methylation Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. . Glucocorticoids or mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations, inactivation of the drug through enzyme production, or removal of the drug through efflux pumps Efflux Pumps Lincosamides.
Last updated: 24 Feb, 2022
Chemical structure of erythromycin (the prototype drug of the macrolide class), featuring a macrocyclic lactone ring Lactone Ring Polyenes with 2 sugars attached
Image: “Erythromycin” by Edgar181. License: Public DomainThe chemical structure of telithromycin (a ketolide):
Notice the similar structure to erythromycin, with a keto group replacing a sugar.
The site of action for macrolides on the 50S ribosomal subunit
tRNA
tRNA
The small RNA molecules, 73-80 nucleotides long, that function during translation (translation, genetic) to align amino acids at the ribosomes in a sequence determined by the mRNA (RNA, messenger). There are about 30 different transfer rnas. Each recognizes a specific codon set on the mRNA through its own anticodon and as aminoacyl trnas (RNA, transfer, amino Acyl), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.
RNA Types and Structure: transfer
RNA
RNA
A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity.
RNA Types and Structure
mRNA
mRNA
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3′ end, referred to as the poly(a) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
RNA Types and Structure: messenger
RNA
RNA
A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity.
RNA Types and Structure
Macrolides | Ketolides | |
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Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption | Erythromycin:
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Rapid absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption |
Distribution |
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Metabolism |
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Excretion |
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There are 3 methods of resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing to macrolides:
Drug class | Mechanism of action | Coverage | Adverse effects |
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Amphenicols |
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Lincosamides Lincosamides The lincosamides, lincomycin and clindamycin, are inhibitors of bacterial protein synthesis. Drugs in this class share the same binding site as that of macrolides and amphenicols; however, they differ in chemical structure. Lincosamides target the 50S ribosomal subunit and interfere with transpeptidation. Lincosamides |
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Macrolides |
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Oxazolidinones Oxazolidinones The oxazolidinones (linezolid and tedizolid) are bacterial protein synthesis inhibitors. Their unique binding site on the 23S ribosomal RNA of the 50S ribosome gives them zero cross-resistance with other antibiotics. Oxazolidinones |
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Gram-positive
Gram-Positive
Penicillins
cocci
Cocci
Bacteriology:
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Antibiotic
sensitivity
Sensitivity
Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives.
Blotting Techniques:
Chart comparing the microbial coverage of different antibiotics for
gram-positive
Gram-Positive
Penicillins
cocci
Cocci
Bacteriology, gram-negative
bacilli
Bacilli
Shigella, and
anaerobes
Anaerobes
Lincosamides.