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Erythromycin-inducible resistance in Staphylococcus aureus: survey of antibiotic classes involved
Abstract:
Certain erythromycin-resistant strains of Staphylococcus aureus remain sensitive to other macrolide antibiotics. If these strains are exposed to low levels of erythromycin, resistance to other antibiotics is induced. The antibiotics to which resistance is induced by erythromycin include: other macrolides as well as lincosaminide, streptogramin (group B) antibiotics but not chloramphenicol, amicetin, streptogramin (group A) antibiotics, tetracyclines, and aminoglycosides. Hence erythromycin induces resistance exclusively towards inhibitors of 50S ribosomal subunit function and, thus far, only with respect to three of six known classes of inhibitors which act on this subunit. In the four strains tested, erythromycin did not induce resistance to pactamycin or bottromycin, to fusidic acid (which inhibits a function involving both subunits), or to other antibiotics which do not inhibit ribosomal function. Thus, by inducing resistance erythromycin could antagonize the action of other antibiotics, and a consistent pattern of antagonism was observed to each antibiotic class in all of the strains in which this could be tested, as well as to other antibiotic members of the same chemical class in each bacterial strain.
Insights
Erythromycin can induce resistance to other antibiotics in resistant Staphylococcus aureus strains. This cross-resistance impacts macrolides, lincosamides, and streptogramins, potentially reducing treatment effectiveness.
Area of Science:
- Microbiology
- Molecular Biology
- Antibiotic Resistance
Background:
- Certain erythromycin-resistant Staphylococcus aureus strains retain sensitivity to other macrolide antibiotics.
- Exposure to low-level erythromycin can induce resistance to a broader spectrum of antibiotics in these strains.
Purpose of the Study:
- To investigate the range of antibiotics to which erythromycin can induce resistance in Staphylococcus aureus.
- To determine the mechanism and pattern of this induced antibiotic resistance and antagonism.
Main Methods:
- Testing erythromycin-exposed Staphylococcus aureus strains for induced resistance to various antibiotic classes.
- Analyzing the ribosomal subunit targets of antibiotics exhibiting induced resistance.
Main Results:
- Erythromycin induced resistance to other macrolides, lincosaminides, and streptogramin (group B) antibiotics.
- No induced resistance was observed for chloramphenicol, amicetin, streptogramin (group A), tetracyclines, aminoglycosides, pactamycin, bottromycin, or fusidic acid.
- Induced resistance was specific to inhibitors of the 50S ribosomal subunit, with consistent antagonism patterns observed.
Conclusions:
- Erythromycin induces cross-resistance exclusively towards inhibitors of the 50S ribosomal subunit.
- This induced resistance can antagonize the action of other antibiotics, impacting therapeutic strategies.