Comparison of arbitrarily primed polymerase chain reaction and cell envelope protein electrophoresis for analysis of
M Vaneechoutte1, A Elaichouni, K Maquelin
1Department of Clinical Chemistry, Microbiology and Immunology, University Hospital Ghent, Belgium.
Abstract:
Two successive Acinetobacter outbreaks in a neonatal intensive care unit were studied with arbitrarily primed polymerase chain reaction (AP-PCR), cell envelope protein electrophoresis (protein fingerprinting) and antibiotic susceptibility testing. AP-PCR fingerprinting and protein fingerprinting yielded identical clustering of the isolates studied. Susceptibility test results were useful for rapid recognition of the outbreaks, but clustering of several isolates was different from the clustering obtained with AP-PCR fingerprinting and protein fingerprinting. Typing results indicated that the two outbreaks, which occurred at a three-month interval, were each caused by a single strain, and that both strains differed from the strains prevailing in the hospital. The strain of one outbreak was identified as A. junii, a species commonly not involved in outbreaks. A. baumannii isolates collected from different departments of this hospital during a period of four years clustered into only five different types. Moreover, strains from different departments of a second hospital belonged to the type prevailing in the first hospital, although there were no apparent connections between the two institutions. This may indicate that only a limited number of strains of the A. calcoaceticus-baumannii complex are involved in nosocomial outbreaks.
Insights
Two Acinetobacter outbreaks in a neonatal intensive care unit were caused by single, distinct strains. Molecular typing methods like AP-PCR and protein fingerprinting effectively identified these outbreak strains, revealing limited Acinetobacter strains cause hospital-acquired infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- Acinetobacter species are significant causes of hospital-acquired infections, particularly in neonatal intensive care units.
- Understanding the genetic relatedness of Acinetobacter strains is crucial for controlling outbreaks.
Purpose of the Study:
- To investigate the molecular epidemiology of two successive Acinetobacter outbreaks in a neonatal intensive care unit.
- To compare the discriminatory power of arbitrarily primed polymerase chain reaction (AP-PCR), protein fingerprinting, and antibiotic susceptibility testing for outbreak investigation.
Main Methods:
- Arbitrarily primed polymerase chain reaction (AP-PCR) for DNA fingerprinting.
- Cell envelope protein electrophoresis (protein fingerprinting).
- Antibiotic susceptibility testing.
Main Results:
- AP-PCR and protein fingerprinting demonstrated identical clustering, identifying single strains responsible for each outbreak.
- Antibiotic susceptibility testing aided rapid outbreak recognition but showed different isolate clustering compared to molecular methods.
- One outbreak strain was identified as Acinetobacter junii, a species not typically associated with outbreaks.
- A limited number of Acinetobacter calcoaceticus-baumannii complex strains appear to be involved in nosocomial outbreaks across different hospitals.
Conclusions:
- AP-PCR and protein fingerprinting are highly effective tools for discriminating Acinetobacter strains during outbreaks.
- Molecular typing provides more accurate strain relatedness information than antibiotic susceptibility testing alone.
- A restricted diversity of Acinetobacter strains may be responsible for a significant proportion of nosocomial infections.
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