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A hospital outbreak of multiresistant Salmonella typhimurium belonging to phage type 193
Abstract:
An outbreak of nosocomial infection was caused by strains of Salmonella typhimurium phage type 193 that were resistant to ampicillin, chloramphenicol, neomycin-kanamycin, streptomycin, spectinomycin, sulfonamides, tetracyclines, trimethoprim, and nalidixic acid. Resistances to drugs other than nalidixic acid were specified by plasmids, and, on the basis of phage typing and plasmid characterization studies, the multiresistant phage type 193 strains were determined to be clonal. In a two-year period, 488 patients infected with these bacteria were identified. An investigation in a pediatric surgical ward, where the outbreak was particularly severe, showed that patients exposed to antibiotics were more likely to be colonized with the epidemic strain and that young debilitated patients were more liable to show clinical signs of infection. Epidemiologic studies suggested that cross infection via the hands of the ward staff was the likely means of propagation of the epidemic.
Insights
A severe nosocomial infection outbreak involved multidrug-resistant Salmonella typhimurium phage type 193. Antibiotic exposure increased colonization risk, and staff hands likely spread the epidemic strain.
Area of Science:
- Infectious Diseases
- Microbiology
- Epidemiology
Background:
- Nosocomial infections pose significant healthcare challenges.
- Multidrug-resistant bacterial strains are an increasing global concern.
- Salmonella typhimurium outbreaks require thorough investigation and control.
Purpose of the Study:
- To investigate a nosocomial outbreak caused by multidrug-resistant Salmonella typhimurium phage type 193.
- To identify risk factors for colonization and clinical infection.
- To determine the transmission dynamics of the epidemic strain.
Main Methods:
- Phage typing and plasmid characterization to determine strain clonality.
- Epidemiological investigation including patient data analysis.
- Assessment of antibiotic exposure and patient vulnerability.
Main Results:
- A clonal outbreak of multidrug-resistant Salmonella typhimurium phage type 193 infected 488 patients over two years.
- Antibiotic exposure was linked to increased colonization with the epidemic strain.
- Young, debilitated patients were more susceptible to clinical infection.
Conclusions:
- The outbreak strain was clonal and resistant to multiple antibiotics, primarily due to plasmids.
- Cross-infection via healthcare staff hands was the probable transmission route.
- Controlling antibiotic use and implementing strict hygiene protocols are crucial for preventing future outbreaks.