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Methicillin-resistant Staphylococcus aureus: a 6-month survey in a Lisbon paediatric hospital
Abstract:
The prevalence of nasal colonization and infection with methicillin-resistant Staphylococcus aureus (MRSA) among patients and staff was studied in a section of a Paediatric Surgical Unit in Lisbon between February and July 1985. Nasal colonization was demonstrated in 41% of burned patients, 5% of non-burned patients and 35% of the nurses. Infection by MRSA occurred in 30% of the burns. The isolates had identical serological patterns, slight differences on phage typing and were resistant to methicillin, cephalosporins, tetracycline, erythromycin and aminoglycosides. A chloramphenicol resistance plasmid of 3 Md was present in those isolates which were chloramphenicol resistant and a small plasmid of 1.7 Md which coded for constitutive erythromycin resistance was present in many isolates. Gentamicin, tetracycline and inducible erythromycin resistance were chromosomal. Several reasons for the apparent low virulence of the isolates are discussed. Attempts to control the outbreak by the discharge of colonized or infected patients, improvement of nursing practices and treatment with temporary removal from work of the colonized nurses did not eliminate the organism from the unit.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization was high in pediatric burn patients (41%) and nurses (35%) in 1985 Lisbon. Control measures failed to eliminate this resistant bacteria from the unit.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat in healthcare settings.
- Understanding MRSA colonization and infection dynamics is crucial for effective control.
Purpose of the Study:
- To investigate the prevalence of MRSA nasal colonization and infection in a pediatric surgical unit.
- To characterize the resistance patterns and genetic elements of MRSA isolates.
- To evaluate the effectiveness of control strategies implemented.
Main Methods:
- Conducted a study in a Lisbon Paediatric Surgical Unit from February to July 1985.
- Assessed nasal colonization in burned patients, non-burned patients, and nursing staff.
- Identified MRSA infections, particularly in burn patients.
- Performed serological typing, phage typing, and antibiotic resistance profiling.
- Analyzed plasmid and chromosomal resistance mechanisms.
Main Results:
- MRSA nasal colonization rates were 41% in burned patients, 5% in non-burned patients, and 35% in nurses.
- MRSA infection occurred in 30% of burn patients.
- Isolates showed consistent serological patterns and resistance to multiple antibiotics including methicillin, cephalosporins, tetracycline, erythromycin, and aminoglycosides.
- Plasmid-mediated resistance to chloramphenicol (3 Md) and constitutive erythromycin resistance (1.7 Md) were observed, alongside chromosomal resistance to gentamicin, tetracycline, and inducible erythromycin.
Conclusions:
- High rates of MRSA nasal carriage were found among vulnerable pediatric patients and healthcare workers.
- MRSA isolates exhibited multi-drug resistance, complicating treatment.
- Implemented control measures, including patient discharge, improved hygiene, and temporary staff removal, were insufficient to eradicate MRSA from the unit.
- The study highlights the challenges in controlling MRSA outbreaks in hospital environments.