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Acquisition of antibiotic resistance by Staphylococcus aureus in skin patients
Abstract:
Acquisition of resistance to neomycin, gentamicin, fusidic acid, or clindamycin has been observed in three strains of Staphylococcus aureus and data from three patients infected with these strains are presented in detail. Clindamycin resistance followed the expected pattern by appearing in a strain of Staph. aureus with dissociated resistance to erythromycin after treatment with erythromycin and clindamycin. Low-level resistance to fusidic acid appeared in two strains in the apparent absence of exposure to that antibiotic. Labile neomycin resistance was encountered in a previously sensitive strain after topical neomycin therapy. Gentamicin resistance appeared in all three strains after topical therapy. In all three strains, a labile resistance (presumably plasmid-mediated) occurred with minimum inhibitory concentrations (MICs) of 64-128 microgram/ml but in one strain a stable resistance with MIC over 3000 microgram/ml appeared.
Insights
Antibiotic resistance in Staphylococcus aureus strains emerged after exposure to various antibiotics, including topical treatments. Resistance patterns varied, with some strains developing labile or stable resistance to gentamicin, neomycin, and fusidic acid.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Antibiotic resistance in Staphylococcus aureus is a growing public health concern.
- Understanding resistance mechanisms is crucial for effective treatment strategies.
Purpose of the Study:
- To detail the acquisition of resistance to neomycin, gentamicin, fusidic acid, and clindamycin in Staphylococcus aureus.
- To analyze resistance patterns in clinical isolates and patient data.
Main Methods:
- Clinical data from three patients infected with resistant Staphylococcus aureus strains were analyzed.
- Antibiotic susceptibility testing was performed to determine minimum inhibitory concentrations (MICs).
Main Results:
- Clindamycin resistance emerged in a strain with pre-existing erythromycin resistance after combined therapy.
- Low-level fusidic acid resistance appeared without direct antibiotic exposure in two strains.
- Labile neomycin resistance developed after topical neomycin treatment.
- Gentamicin resistance was observed in all three strains following topical therapy, with varying stability and MICs.
Conclusions:
- Antibiotic exposure, including topical applications, can drive the emergence of Staphylococcus aureus resistance.
- Observed resistance patterns suggest both expected and unexpected mechanisms, including potential plasmid-mediated resistance.
- Further research is needed to fully elucidate the mechanisms and clinical implications of these resistance developments.