Identification of clinical isolates of Acinetobacter baumannii from Iran and study of their heterogeneity
Parisa Sadeghi1, Azar Dokht Khosravi2, Abdolrazagh Hashemi Shahraki3
1Clinical Biochemistry Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran; Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Background:
Acinetobacter baumannii has become one of the most serious causative agents of nosocomial infections due to its significant ability to survive on hospital surfaces. It is mainly an emerging opportunistic pathogen infecting patients in intensive care units. This study was aimed to identify the clinical isolates of A. baumannii and to investigate their heterogeneity using polymerase chain reaction (PCR)-based typing methods.
Methods:
A total of 197 nonduplicate isolates recovered from a wide range of clinical samples were subjected to conventional cultural and biochemical tests. For those isolates that were preliminary identified as A. baumannii, rpoB-based PCR with subsequent restriction fragment length polymorphism (RFLP) using two restriction enzymes (TagI and HaeIII) was performed to investigate the genetic diversity of the strains and their presumptive relationships with different clinical presentation of the disease caused by this pathogen.
Results:
In total, 50 isolates (25.4%) were identified as A. baumannii using conventional phenotypic methods with subsequent confirmation by rpoB sequencing. RFLP analysis demonstrated five different restriction enzyme patterns, designated as A-E clusters. Most A. baumannii isolates were categorized under Cluster A (32%). We found no significant relationship between clinical presentation and the clustering of the isolates.
Conclusion:
This study showed that the rpoB region possesses high discriminatory power to identify the isolates to the species level. This marker showed high interspecies variability that might be useful for strain typing. The results also suggest the possibility of the existence of a predominant clone of A. baumannii among infected patients in Iran.
Insights
Acinetobacter baumannii, a common cause of hospital infections, shows genetic diversity. This study used rpoB gene sequencing and RFLP to analyze clinical isolates, revealing five distinct clusters but no link to patient outcomes.
Area of Science:
- Clinical Microbiology
- Molecular Epidemiology
- Infectious Diseases
Background:
- Acinetobacter baumannii is a significant cause of nosocomial infections, thriving on hospital surfaces.
- It frequently infects patients in intensive care units, posing a major healthcare challenge.
Purpose of the Study:
- To identify clinical isolates of Acinetobacter baumannii.
- To investigate the genetic heterogeneity of these isolates using molecular typing methods.
Main Methods:
- Conventional cultural and biochemical tests were used for preliminary identification.
- Polymerase chain reaction (PCR)-based rpoB gene sequencing and restriction fragment length polymorphism (RFLP) were employed for genetic analysis.
Main Results:
- Fifty Acinetobacter baumannii isolates were identified from 197 clinical samples.
- RFLP analysis revealed five distinct genetic clusters (A-E), with Cluster A being the most prevalent (32%).
- No significant correlation was found between isolate clusters and clinical presentation.
Conclusions:
- The rpoB gene marker demonstrates high discriminatory power for Acinetobacter baumannii species identification and strain typing.
- The findings suggest the potential dominance of a specific Acinetobacter baumannii clone in Iran.
- Further research into strain typing is warranted for effective infection control.
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