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Control of infection with multiple antibiotic resistant bacteria in a hospital renal unit: the value of plasmid
C S Reed1, S P Barrett, E J Threlfall
1Department of Medical Microbiology, St. Mary's Hospital Medical School, London, U.K.
Abstract:
An outbreak of infections due to multiple antibiotic-resistant bacteria took place over a period of approximately 18 months in a renal unit. Strains of Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Citrobacter spp. and Pseudomonas spp. were involved, and a variety of antibiotic resistances was encountered. Closely related plasmids encoding resistance to aztreonam, ceftazidime and piperacillin, possibly derived from an archetypal plasmid of 105 kb were found in the majority of isolates examined. After limiting the use of aztreonam the incidence of new patient isolates of multiple-resistant organisms was greatly reduced. This study demonstrated how molecular studies can contribute to the control of an outbreak situation in a hospital unit by providing an impetus to reduce the use of specific antibiotics.
Insights
Limiting aztreonam use significantly reduced hospital-acquired infections from multidrug-resistant bacteria. Molecular studies aided outbreak control by guiding antibiotic stewardship, highlighting the impact of targeted interventions.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Molecular Epidemiology
Background:
- An 18-month outbreak of multidrug-resistant bacterial infections occurred in a renal unit.
- Involved pathogens included Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Citrobacter spp., and Pseudomonas spp.
- Multiple antibiotic resistances were prevalent among the isolated strains.
Purpose of the Study:
- To investigate the molecular basis of an antibiotic-resistant bacterial outbreak in a hospital setting.
- To assess the impact of molecular findings on infection control strategies.
- To evaluate the effectiveness of reducing specific antibiotic use in controlling the outbreak.
Main Methods:
- Plasmid analysis to identify genetic relatedness and resistance mechanisms.
- Molecular typing of bacterial isolates.
- Monitoring of new patient isolates and antibiotic usage patterns.
Main Results:
- Closely related plasmids encoding resistance to aztreonam, ceftazidime, and piperacillin were identified in most isolates.
- These resistance plasmids may have originated from a common 105 kb archetypal plasmid.
- A significant reduction in new patient isolates of multidrug-resistant organisms was observed after limiting aztreonam use.
Conclusions:
- Molecular studies, particularly plasmid analysis, are crucial for understanding and controlling hospital outbreaks.
- Reducing the use of specific antibiotics, guided by molecular data, can effectively curb the spread of multidrug-resistant bacteria.
- This study underscores the importance of antibiotic stewardship informed by molecular epidemiology in clinical settings.