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[Emergence of drug-resistant gram-positive pathogenic bacteria]
A Marchese1, G C Schito, E A Debbia
1Istituto di Microbiologia, Università di Genova, Largo R. Benzi 10, 16132 Genova.
Abstract:
Staphylococcus aureus is a common cause of soft tissue infection, e.g. impetigo, cellulitis, or wound infection, and causes osteomyelitis, arthritis, bacteremia with metastatic infection, and scalded skin and toxic shock syndromes. Coagulase-negative staphylococci have become increasingly important causes of nosocomial bacteremia associated with invasive monitoring, intravascular catheters and prosthetic heart valves or joints. Most staphylococci produce blactamase and are resistant to penicillin. An increasing proportion of S. aureus have intrinsic resistance to methicillin (MRSA) and present major problems in hospitals for the control of cross infection. The glycopeptides, teicoplanin and vancomycin, are the antibiotics of first choice for treatment of these infections. After the first report describing a Japanese clinical isolate of vancomycin-resistant S. aureus (VRSA), several papers have documented the emergence of these microorganisms. Since the development and spreading of this phenomenon which is perceived as a fearsome threat to the already difficult therapy of nosocomial infections due to the prevalence of heterogeneous vancomycin resistance, we found the incidence of MRSA exceeds 35% in our hospital. Out of 179 methicillin-resistant S. aureus isolated during 1997-1998, two strains (1.1%) gave subclones with vancomycin MICs of 8 mg/L. PFGE showed identical restriction patterns for both isolates, suggesting transfer of a single clone between two different patients.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) infections are a growing concern. Two MRSA strains isolated in our hospital showed emerging resistance to vancomycin, indicating a potential threat to patient treatment.
Area of Science:
- Microbiology
- Infectious Diseases
- Antibiotic Resistance
Context:
- Staphylococcus aureus is a significant pathogen causing various infections, including skin, bone, and bloodstream infections.
- Methicillin-resistant Staphylococcus aureus (MRSA) is a prevalent cause of hospital-acquired infections, complicating treatment due to resistance to beta-lactam antibiotics.
- Vancomycin and teicoplanin are primary treatments for MRSA infections, but emerging resistance poses a therapeutic challenge.
Purpose:
- To investigate the emergence of vancomycin resistance in clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA).
- To characterize MRSA strains exhibiting reduced susceptibility to vancomycin.
- To assess the potential for clonal spread of vancomycin-resistant MRSA within a hospital setting.
Summary:
- During 1997-1998, 179 MRSA strains were isolated, with two strains (1.1%) developing subclones demonstrating vancomycin Minimum Inhibitory Concentrations (MICs) of 8 mg/L.
- These vancomycin-resistant MRSA (VRSA) isolates exhibited identical restriction patterns via Pulse Field Gel Electrophoresis (PFGE).
- The findings suggest the successful transfer of a single vancomycin-resistant MRSA clone between patients, highlighting a significant public health concern.
Impact:
- The emergence of VRSA strains, even at low incidence, represents a critical threat to managing nosocomial infections.
- This study underscores the need for vigilant surveillance and infection control measures to prevent the spread of antibiotic-resistant bacteria.
- Understanding the mechanisms and transmission of vancomycin resistance in MRSA is crucial for developing effective therapeutic strategies.