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Diversity of plasmids in Staphylococcus saprophyticus isolated from urinary tract infections in women
J A Cristino1, A T Pereira, L G Andrade
1Department of Microbiology, Faculty of Medicine, University of Lisbon, Lisboa, Portugal.
Abstract:
A group of 150 Staphylococcus saprophyticus strains isolated from urinary tract infections in women were included in this study. Antimicrobial susceptibility tests showed that these isolates were sensitive to most antimicrobial agents. All strains were sensitive to penicillin, cephalothin, gentamicin, kanamycin, trimethoprim and nitrofurantoin. Resistance to tetracycline was present in 10.6% of the strains, to chloramphenicol in 4%, to erythromycin in 1.3% and to streptomycin in 1.3%. All strains were resistant to cadmium chloride as well as to novobiocin and nalidixic acid. Plasmid analysis showed that 82% of the strains harboured plasmids, some of them with complex plasmid profiles. Most plasmids were considered to be cryptic, although antibiotic resistance plasmids were identified in 18 isolates. Tetracycline resistance was encoded by a plasmid of c. 2.8 MDa, chloramphenicol resistance by a plasmid of c. 2.9 MDa and erythromycin resistance by a plasmid of c. 1.6 MDa. Streptomycin resistance could not be linked to the presence of any specific plasmid. Plasmid profiling seemed to be a good method for differentiating among S. saprophyticus strains.
Insights
This study analyzed 150 Staphylococcus saprophyticus strains from urinary tract infections, finding most sensitive to common antibiotics but resistant to novobiocin and nalidixic acid. Plasmid analysis revealed resistance genes in some strains, suggesting plasmid profiling aids in strain differentiation.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Staphylococcus saprophyticus is a common cause of urinary tract infections (UTIs) in women.
- Understanding antimicrobial resistance patterns and genetic elements like plasmids is crucial for effective treatment and infection control.
Purpose of the Study:
- To investigate the antimicrobial susceptibility profile of Staphylococcus saprophyticus strains isolated from female UTIs.
- To analyze the presence and characteristics of plasmids in these strains and their potential role in antibiotic resistance.
- To evaluate plasmid profiling as a method for differentiating Staphylococcus saprophyticus strains.
Main Methods:
- Antimicrobial susceptibility testing was performed on 150 Staphylococcus saprophyticus isolates.
- Plasmid DNA was extracted and analyzed using various techniques.
- Plasmid profiles were compared to antibiotic resistance patterns.
Main Results:
- All isolates were sensitive to penicillin, cephalothin, gentamicin, kanamycin, trimethoprim, and nitrofurantoin.
- Resistance was observed for tetracycline (10.6%), chloramphenicol (4%), erythromycin (1.3%), and streptomycin (1.3%).
- All strains were resistant to cadmium chloride, novobiocin, and nalidixic acid.
- 82% of strains harbored plasmids, with 18 isolates showing antibiotic resistance plasmids.
- Specific plasmids were linked to tetracycline, chloramphenicol, and erythromycin resistance.
- Plasmid profiling demonstrated utility in differentiating Staphylococcus saprophyticus strains.
Conclusions:
- Staphylococcus saprophyticus strains from female UTIs exhibit varied antimicrobial susceptibility, with notable resistance to certain agents.
- Plasmids play a role in encoding antibiotic resistance in some strains.
- Plasmid profiling is a valuable tool for the epidemiological characterization and differentiation of Staphylococcus saprophyticus.