Recurrent bacteremia caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii complex

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Genomics

Background:

• Recurrent bacteremia caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex presents a significant clinical challenge.
• Distinguishing between relapse and reinfection is crucial for effective patient management and antimicrobial stewardship.
• Immunocompromised patients, particularly those with central venous catheters, are at higher risk for ACB complex bacteremia.

Purpose of the Study:

• To investigate the clinical and microbiological features of recurrent bacteremia attributed to the ACB complex.
• To differentiate between relapse and reinfection using molecular typing methods.
• To assess antimicrobial susceptibility patterns within the ACB complex.

Main Methods:

• Genomic species identification of ACB complex isolates using 16S-23S rRNA gene intergenic spacer sequencing.
• Genotyping through random amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE).
• Clinical data collection on patient characteristics, infection sources, and outcomes.

Main Results:

• 5.6% of 446 ACB complex bacteremia cases resulted in recurrence.
• Relapse occurred in 48% of recurrent cases (A. nosocomialis or A. baumannii).
• A. baumannii exhibited lower antimicrobial susceptibility compared to A. nosocomialis and A. pittii.

Conclusions:

• Relapse of ACB complex bacteremia is possible in immunocompromised patients, especially with central venous catheters.
• Molecular identification to the genospecies level is essential for differentiating relapse from reinfection.
• Understanding recurrence patterns informs clinical strategies for managing ACB complex infections.