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Macrolide-lincosamide-streptogramin B (MLS) resistance in cutaneous propionibacteria: definition of phenotypes
Abstract:
Erythromycin-resistant propionibacteria isolated from the skin of antibiotic-treated acne patients were found to express four different patterns of resistance to a set of eight MLS antibiotics. The majority of isolates (48/89 strains) were constitutively resistant to 14- and 16-membered ring macrolide, lincosamide and streptogramin B-type antibiotics. MICs of josamycin (0.5-16 mg/l) and spiramycin (0.5-128 mg/l) were lower than those of erythromycin, oleandomycin and tylosin (64 to less than 512 mg/l). Two strains of Propionibacterium granulosum exhibited inducible MLS resistance. Both 14- and 16-membered ring macrolides and virginiamycin S induced clindamycin resistance in these strains. Fifteen isolates demonstrated a similar phenotype to the inducible strains but were non-inducible by erythromycin. A fourth group of strains demonstrated high level resistance to all five macrolides tested (MIC greater than or equal to 128 mg/l) but were sensitive to virginiamycin S. The phenotype displayed by these strains is not compatible with the expression of methylase genes as currently known, nor with the action of an erythromycin esterase which hydrolyses only 14-membered ring macrolides. The resistance patterns of 12 isolates could not be classified into any of the above phenotypic classes. Therefore, the majority of erythromycin resistant propionibacteria express MLS resistance which is phenotypically similar to that coded for by several well characterized RNA methylase (erm) genes.
Insights
Erythromycin-resistant propionibacteria show diverse multidrug and macrolide-lincosamide-streptogramin B (MLS B) resistance patterns. Most strains exhibit constitutive MLS B resistance, with some displaying inducible or novel resistance mechanisms.
Area of Science:
- Microbiology
- Molecular Biology
- Dermatology
Background:
- Propionibacteria are skin commensals often implicated in acne.
- Antibiotic treatment for acne can lead to the emergence of resistant bacterial strains.
- Understanding resistance mechanisms is crucial for effective acne management.
Purpose of the Study:
- To characterize the multidrug and macrolide-lincosamide-streptogramin B (MLS B) resistance patterns in erythromycin-resistant Propionibacteria.
- To investigate the specific mechanisms of MLS B resistance in these isolates.
Main Methods:
- Isolation of Propionibacteria from antibiotic-treated acne patients.
- Determination of Minimum Inhibitory Concentrations (MICs) for eight MLS B antibiotics.
- Phenotypic characterization of inducible and constitutive resistance patterns.
Main Results:
- The majority of isolates (48/89) exhibited constitutive resistance to 14- and 16-membered ring macrolides, lincosamides, and streptogramin B antibiotics.
- Two Propionibacterium granulosum strains showed inducible MLS B resistance, triggered by various macrolides and virginiamycin S.
- A novel resistance phenotype, not explained by known methylase or esterase genes, was observed in some strains.
Conclusions:
- Erythromycin-resistant Propionibacteria display diverse MLS B resistance phenotypes.
- The prevalence of constitutive MLS B resistance suggests a significant challenge in treating acne with these antibiotics.
- Further research is needed to elucidate the molecular basis of the unclassified resistance patterns.