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Molecular characterisation and control of Acinetobacter baumannii isolates resistant to multi-drugs emerging in
Ayşe Ertürk1, Ayşegül Çopur Çiçek2, Aziz Gümüş3
1Department of Infectious Diseases, School of Medicine, Recep Tayyip Erdogan University, Rize, Turkey. ayseace25@hotmail.com.
Background:
A nosocomial outbreak of Acinetobacter baumannii (AB) infections occurred among intensive care units (ICU) (surgery, medical, cardiovascular surgery, coronary unit) of Recep Tayyip Erdogan University Medical School (Rize, Turkey) between January 2011 and May 2012. The identification of isolates and clonal relation among them were investigated by molecular techniques.
Methods:
A total of 109 AB isolates were obtained from 64 clinical materials from 54 ICU patients and 3 from the hands of healthcare workers (HCWs) of 42 environmental samples. The isolates were identified by 16S rDNA sequencing and OXA- specific PCR. The clonal relation between isolates was investigated by PFGE methods using ApaI restriction enzyme.
Results:
All isolates were determined as AB by 16S rDNA sequencing and OXA-spesific PCR. While the blaOXA-51-like gene was amplified in all isolates, the blaOXA-23-like gene was amplified from 103 isolates. The PFGE pattern generated 9 pulsotypes and showed that the isolates from patients, HCWs, and the environment were genetically related. In 7 of these pulsotypes, there were 107 strains (98%) showing similar PFGE profiles that cannot be distinguished from each other, ranging from 2 to 53. The remaining 2 pulsotypes were comprised of strains closely associated with the main cluster. Two major groups were discovered with similarity coefficient of 85% and above. The first group consisted of 97 strains that are similar to each other at 92.7% rate, and the second group consisted of 12 strains that are 100% identical.
Conclusions:
The common utilization of the blood gas device among ICU was the reason for the contamination. AB strains can remain stable for a long period of time, although due to the disinfection procedures applied in hospitals, there is a small chance that the same clone might reappear and cause another epidemic. For that reason, the resistance profiles of the strains must be continuously followed with amplification-based methods, and these methods should be used to support the PFGE method in the short term.
Insights
A hospital outbreak of Acinetobacter baumannii infections was traced to a shared blood gas device. Molecular methods confirmed genetic relatedness among patient, healthcare worker, and environmental isolates, highlighting the need for continuous monitoring.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Molecular Epidemiology
Background:
- A nosocomial outbreak of Acinetobacter baumannii (AB) infections occurred in intensive care units (ICUs) at Recep Tayyip Erdogan University Medical School between January 2011 and May 2012.
- The study aimed to identify the source and clonal relationships of the AB isolates involved in the outbreak.
Purpose of the Study:
- To investigate the molecular epidemiology of an Acinetobacter baumannii outbreak in ICUs.
- To identify the source of infection and the clonal relatedness of isolates from patients, healthcare workers, and the environment.
Main Methods:
- A total of 109 AB isolates were collected from clinical samples, healthcare workers' hands, and environmental surfaces.
- Isolates were identified using 16S rDNA sequencing and OXA-specific PCR.
- Clonal relatedness was assessed using Pulse Field Gel Electrophoresis (PFGE) with ApaI restriction enzyme.
Main Results:
- All isolates were confirmed as Acinetobacter baumannii.
- The blaOXA-23-like gene was detected in 103 out of 109 isolates.
- PFGE analysis revealed 9 pulsotypes, indicating genetic relatedness among patient, healthcare worker, and environmental isolates. A dominant clone (98% of strains) was identified, with two major clonal groups showing high similarity.
Conclusions:
- The common use of a blood gas device in the ICU was identified as the source of contamination.
- Acinetobacter baumannii strains can persist, and the same clone may re-emerge, necessitating continuous monitoring of resistance profiles.
- Amplification-based methods should complement PFGE for short-term monitoring and outbreak investigations.
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