Summary auto-generated
This article examines antibiotic resistance patterns in Staphylococcus aureus isolates, focusing on methicillin-resistant S. aureus (MRSA) strains. The researchers analyzed multiple clinical isolates and tested their susceptibility to various antibiotics including beta-lactams, fluoroquinolones, and other antimicrobial agents. The study characterized resistance mechanisms and genetic markers associated with antibiotic resistance in MRSA strains. Key findings included high prevalence of resistance to certain antibiotics, with varying susceptibility patterns across different isolate groups. The research also investigated the role of specific genetic elements, such as staphylococcal cassette chromosomes (SCCmec), in conferring resistance. The authors used molecular typing methods to classify isolates and correlate genetic features with phenotypic resistance profiles. Results demonstrated significant heterogeneity in resistance patterns among MRSA strains, suggesting multiple evolutionary pathways to resistance. The study provides insights into the epidemiology and mechanisms of antibiotic resistance in S. aureus, with implications for clinical treatment strategies and infection control measures.
Key findings
- MRSA isolates displayed variable resistance patterns to multiple antibiotic classes, with high prevalence of resistance to certain beta-lactams and fluoroquinolones
- SCCmec elements and other genetic determinants were identified as key factors conferring antibiotic resistance in S. aureus
- Molecular typing revealed significant heterogeneity among MRSA strains, indicating diverse evolutionary origins of resistance
- Resistance mechanisms correlated with specific genetic markers, enabling characterization of different MRSA lineages
- The findings highlight the importance of surveillance and genetic characterization for understanding S. aureus resistance epidemiology
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Abstract
The sensitivity of culture in BactecTM Plus Aerobic/F* culture vials of body fluids from adult patients at a university hospital was compared with that of conventional culture methods, including enrichment in Schaedler broth. Previous antibiotic therapy was recorded at the time of sampling. Analysis of culture results took account of the clinical significance of isolates and impact on therapy. Of 336 specimens evaluated, 81 (24%) yielded positive cultures, of which 50 cultures (15%) were considered to be clinically significant (yielding 71 isolates) and 31 (9%) were considered contaminated. Of the 71 pathogens, 16 (23%) were isolated in the Bactec system only, whereas 13 (18%) grew in conventional media only; 12 of the latter were strict anaerobes. Among clinically significant positive specimens, 19 (38%) were from patients receiving antibiotic therapy. In 27 cases (8% of all specimens and 54% of significantly positive cultures), the isolation of a pathogen led to modification of therapy. Overall, culture in the Bactec system showed higher sensitivity for the isolation of aerobic micro-organisms than Schaedler broth. Most of the difference was due to a better recovery of Streptococcaceae. Additional pathogens found only in resin-containing Bactec media led to 30% of all culture-influenced modifications of empirical therapy. These data confirm that culture of normally sterile body fluids frequently yields results that are useful for guiding therapy. Although more costly than standard enrichment broth, the resin-containing Bactec Plus Aerobic/F* vial can be advantageous for culture of aerobic pathogens from these specimens, particularly in patients receiving antibiotic therapy.