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Sensitivity to antibacterials of Staphylococcus aureus isolated from different types of skin infections
S Nishijima1, S Namura, M Nakagawa
1Division of Dermatology, Kansai Medical University Kori Branch Hospital, Osaka, Japan.
Abstract:
We examined the antibacterial susceptibility of Staphylococcus aureus isolated from several types of skin infections, which were classified into four groups: (i) impetigo, (ii) folliculitis, (iii) atopic dermatitis and eczema and (iv) ulcers and decubitus. The 50% minimal inhibitory concentration (MIC50) of the antibacterial agents was 3.13 micrograms/ml or lower, except that of gentamicin with isolates from the impetigo groups (25 micrograms/ml). The MIC90 of gentamicin was 50 micrograms/ml or more for isolates from all four groups. The isolates from the ulcers and decubitus group showed multiple resistance against antibacterial agents. The frequency of methicillin-resistant S. aureus was low, but was highest, at 25%, in the isolates from the ulcers and decubitus group. Few isolates from the atopic dermatitis and eczema group were resistant, and there was little difference in antibacterial resistance between isolates from atopic dermatitis and eczema.
Insights
Staphylococcus aureus from skin infections shows varying antibiotic resistance. Ulcer isolates displayed multiple drug resistance, while impetigo isolates were less susceptible to gentamicin.
Area of Science:
- Microbiology
- Dermatology
- Infectious Diseases
Background:
- Staphylococcus aureus is a common cause of various skin infections.
- Understanding antibiotic resistance patterns is crucial for effective treatment.
- Skin infection types may influence bacterial susceptibility to antimicrobials.
Purpose of the Study:
- To assess the antibacterial susceptibility of Staphylococcus aureus strains isolated from different skin infection types.
- To identify specific resistance patterns associated with each infection category.
Main Methods:
- Bacterial isolates of Staphylococcus aureus were collected from four distinct skin infection groups: impetigo, folliculitis, atopic dermatitis/eczema, and ulcers/decubitus.
- Minimal inhibitory concentration (MIC50 and MIC90) values for various antibacterial agents were determined.
- The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) was evaluated.
Main Results:
- Most antibacterial agents showed a minimal inhibitory concentration (MIC50) of ≤3.13 µg/ml.
- Gentamicin exhibited higher MIC50 (25 µg/ml) and MIC90 (≥50 µg/ml) values across all groups, particularly in impetigo isolates.
- Isolates from ulcers and decubitus demonstrated significant multiple drug resistance.
- Methicillin-resistant Staphylococcus aureus (MRSA) frequency was low overall but highest (25%) in the ulcers/decubitus group.
- Isolates from atopic dermatitis and eczema showed limited resistance.
Conclusions:
- Antibiotic susceptibility of Staphylococcus aureus varies significantly depending on the type of skin infection.
- Gentamicin resistance is a concern, especially in impetigo and ulcer/decubitus infections.
- The high prevalence of multiple drug resistance and MRSA in ulcer/decubitus isolates highlights the need for targeted therapeutic strategies.