Insertion Sequences within Oxacillinases Genes as Molecular Determinants of Acinetobacter baumannii Resistance to
Dagmara Depka1,2, Tomasz Bogiel1,2, Mateusz Rzepka1,2
1Microbiology Department, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, 85-094 Bydgoszcz, Poland.
Abstract:
Carbapenem-resistant Acinetobacter baumannii is one of the major problems among hospitalized patients. The presence of multiple virulence factors results in bacteria persistence in the hospital environment. It facilitates bacterial transmission between patients, causing various types of infections, mostly ventilator-associated pneumonia and wound and bloodstream infections. A. baumannii has a variable number of resistance mechanisms, but the most commonly produced are carbapenem-hydrolyzing class D β-lactamases (CHDLs). In our study, the presence of blaOXA-23, blaOXA-40 and blaOXA-51 genes was investigated among 88 clinical isolates of A. baumannii, including 53 (60.2%) strains resistant to both carbapenems (meropenem and imipenem) and 35 (39.8%) strains susceptible to at least meropenem. Among these bacteria, all the isolates carried the blaOXA-51 gene. The blaOXA-23 and blaOXA-40 genes were detected in two (5.7%) and three (8.6%) strains, respectively. Among the OXA-23 carbapenemase-producing A. baumannii strains (n = 55), insertion sequences (ISAba1) were detected upstream of the blaOXA-23 gene in fifty-two (94.5%) carbapenem-resistant and two (3.6%) meropenem-susceptible isolates. A. baumannii clinical strains from Poland have a similar antimicrobial resistance profile as those worldwide, with the presence of ISAba1 among blaOXA-23-positive isolates also being quite common. Carbapenem resistance among A. baumannii strains is associated with the presence of CHDLs, especially when insertion sequences are present.
Insights
Carbapenem-resistant Acinetobacter baumannii is a major hospital threat. Carbapenem-hydrolyzing class D beta-lactamases (CHDLs) and insertion sequences (IS) are key resistance factors in Acinetobacter baumannii.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Carbapenem-resistant Acinetobacter baumannii (CRAB) poses a significant threat to hospitalized patients, causing severe infections.
- CRAB's persistence in healthcare settings is linked to its virulence factors and efficient transmission.
- Carbapenem-hydrolyzing class D beta-lactamases (CHDLs) are primary mechanisms of carbapenem resistance in A. baumannii.
Purpose of the Study:
- To investigate the prevalence of carbapenemase genes (blaOXA-23, blaOXA-40, blaOXA-51) in clinical Acinetobacter baumannii isolates.
- To determine the association between carbapenem resistance and the presence of specific CHDL genes and insertion sequences.
Main Methods:
- Analysis of 88 clinical Acinetobacter baumannii isolates.
- Detection of blaOXA-23, blaOXA-40, and blaOXA-51 genes using molecular methods.
- Investigation of insertion sequence ISAba1 upstream of blaOXA-23.
Main Results:
- All isolates harbored the blaOXA-51 gene.
- blaOXA-23 and blaOXA-40 were detected in 5.7% and 8.6% of isolates, respectively.
- Insertion sequence ISAba1 was frequently found upstream of blaOXA-23 in carbapenem-resistant isolates (94.5%).
Conclusions:
- Acinetobacter baumannii clinical strains in Poland exhibit resistance profiles similar to global trends.
- CHDLs, particularly blaOXA-23, are associated with carbapenem resistance in A. baumannii.
- The presence of ISAba1 insertion sequences significantly contributes to carbapenem resistance mediated by CHDLs.
Related Concept Videos
01:30Development of Antibiotic Resistance
00:57Antibiotic Selection
01:28Gene Regulation in Microbial Communities: Quorum Sensing