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[Molecular epidemiology of a streptococcus pyogenes related nosocomial outbreak in a burn unit]
Alberto Fica1, Jorge Fernández, Germán Ebensperger
1Departamento de Medicina, Hospital Clínico Universidad de Chile, Av. Santos Dumont 999, Independencia, Santiago. afica@ns.hospital.uchile.cl
Insights
Molecular analysis revealed two distinct groups of Group A Streptococcal (GAS) infections during a 1996 burn unit outbreak. One group caused severe disease, including toxic shock syndrome, while the other was linked to a healthcare worker carrier.
Area of Science:
- Microbiology
- Epidemiology
- Molecular Biology
Context:
- Group A Streptococcal (GAS) infections are increasing globally in severity.
- A 1996 nosocomial outbreak in a pediatric burn unit involved seven patients with severe GAS infections.
- The outbreak likely originated from a source patient and spread within the facility.
Purpose:
- To conduct a molecular analysis of an apparently clonal Group A Streptococcal outbreak.
- To identify the genetic relatedness of bacterial isolates from patients and healthcare workers.
Summary:
- Molecular methods including Random Amplified Polymorphic DNA (RAPD) analysis, Pulsed Field Gel Electrophoresis (PFGE), and PCR for speA, speB, and speC genes were employed.
- Two distinct GAS groups were identified: one associated with invasive disease and the speA gene, and another linked to a healthcare worker carrier.
- The second group showed further differentiation based on speB profiles.
Impact:
- Random Amplified Polymorphic DNA (RAPD) analysis demonstrated effectiveness comparable to PFGE for epidemiological analysis of GAS infections.
- This study highlights the utility of molecular techniques in tracking and understanding bacterial outbreaks in healthcare settings.
- Findings contribute to improved infection control strategies for GAS.
Background:
Group A Streptococcal (GAS) infections have increased in frequency and severity worldwide. During April 1996, a nosocomial outbreak associated to GAS infections affected seven patients admitted to a pediatric burn unit. The causative organism was likely disseminated from the source patient to another child in the emergency room before he was transferred to the burn unit. Patients developed burn infections or invasive disease. One of them died due to a toxic shock syndrome and 3 other lost their skin grafts. Perineal and nasal microbiological surveillance of 42 related health care workers identified only one of them as carrier of S pyogenes.
Aim:
To report a molecular analysis of an apparently clonal outbreak.
Material And Methods:
The available isolates were analyzed by molecular methods including random amplified polymorphic DNA analysis (RAPD) with 4 different primers, Sma-I pulsed field gel electrophoresis (PFGE) analysis, and speA, speB and speC detection by polymerase chain reaction (PCR).
Results:
Two phylogenetically distant and sequentially isolated bacterial groups were identified either by RAPD analysis with selected primers or by Smal-PFGE analysis. The first group involved isolates identified in two patients that included the lethal case. The second bacterial group comprised 5 clinical isolates and the perineal and nasal isolates obtained from a health care worker. Only strains belonging to the first group harbored the speA gene and were associated with invasive disease. The second group could be split further in two subgroups according to their speB profile.
Conclusions:
RAPD analysis with selected primers can reproduce the PFGE-discriminating ability on the epidemiological analysis of GAS infections.