Acinetobacter baumannii multidrug-resistant strain occurrence in liver recipients with reference to other high-risk
I Netsvyetayeva1, M Sikora, M Golas
1Department of Medical Microbiology, Warsaw Medical University, and Regional Hospital of Traumatology, St Anna, Warsaw, Poland. irenanets@gmail.com
Introduction:
The increasing clinical significance of Acinetobacter baumannii species is due to its ability to survive in hospital environments, its species-specific multidrug resistance, and its ability to instantly develop various drug-resistance mechanisms through antibiotic pressure.
Materials And Methods:
We identified 16 A baumannii strains isolated from patients presenting postoperative infections in 2010. A baumannii isolates were obtained from clinical specimens by standard microbiologic methods. As previously described, we performed polymerase chain reaction (PCR) analysis for carbapenemase-encoding genes (VIM, IMP, SPM, OXA23, OXA24, OXA51, OXA58) in Acinetobacter spp.
Results:
The double-disk synergy test phenotypic method did not detect any A baumannii strains producing metallo-beta-lactamaus cultured from swabs from all the patient groups. No products of PCR amplification with specific starters for VIM, IMP, and SPM (Sao Paulo metallo-β-lactamase) genes were found. All analyzed strains were colistin-sensitive. Among five strains from liver recipients, one was imipenem- and meropenem-resistant. Four among six strains isolated from cancer patients were resistant to imipenem and/or meropenem; 1/5 were imipenem-and meropenem-resistant; 1, meropenem-resistant and imipenem-sensitive; 1, meropenem- and imipenem-resistant; and 1 with intermediate resistance to both meropenem and imipenem among swabs cultured from patients with postoperative complication after bone fracture. Fifteen among 16 analyzed A baumannii strains had an OXA51 gene. Two among five A baumannii strains isolated in liver recipients had only an OXA51 gene; one, OXA51 and OXA24 genes; one, OXA51 and OXA23 genes.
Insights
Acinetobacter baumannii exhibits significant multidrug resistance. This study found OXA51 genes in most strains, with some also carrying OXA23 or OXA24, indicating complex resistance mechanisms in hospital-acquired infections.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Acinetobacter baumannii is a significant pathogen due to its environmental survival, inherent multidrug resistance, and rapid development of resistance.
- Antibiotic pressure drives the evolution of diverse resistance mechanisms in A. baumannii.
Purpose of the Study:
- To investigate the prevalence of carbapenemase-encoding genes in Acinetobacter baumannii strains.
- To characterize the antimicrobial resistance profiles of A. baumannii isolates from postoperative infections.
Main Methods:
- Identification of 16 A. baumannii strains from postoperative infections.
- Polymerase chain reaction (PCR) analysis for carbapenemase genes (VIM, IMP, SPM, OXA23, OXA24, OXA51, OXA58).
- Phenotypic testing using double-disk synergy and antimicrobial susceptibility testing.
Main Results:
- No metallo-beta-lactamase-producing strains were detected phenotypically or by PCR for VIM, IMP, and SPM genes.
- All strains were susceptible to colistin. Resistance to imipenem and/or meropenem was observed in some strains, particularly from liver recipients and cancer patients.
- Fifteen of 16 strains harbored the OXA51 gene; some also carried OXA23 or OXA24 genes, suggesting diverse carbapenemase gene carriage.
Conclusions:
- A. baumannii strains in this cohort primarily carried OXA-type carbapenemase genes, with OXA51 being highly prevalent.
- The absence of VIM, IMP, and SPM genes suggests a different resistance mechanism profile.
- Understanding these genetic determinants is crucial for managing A. baumannii infections and guiding treatment strategies.
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