Virulence potential of multidrug-resistant Acinetobacter baumannii isolates from COVID-19 patients on mechanical ventilation: The first report from Serbia

Abstract

Since the WHO declared the COVID-19 pandemic in March 2020, the disease has spread rapidly leading to overload of the health system and many of the patients infected with SARS-CoV-2 needed to be admitted to the intensive care unit (ICU). Around 10% of patients with the severe manifestation of COVID-19 need noninvasive or invasive mechanical ventilation, which represent a risk factor for Acinetobacter baumannii superinfection. The 64 A. baumannii isolates were recovered from COVID-19 patients admitted to ICU at General Hospital "Dr Laza K. Lazarević" Šabac, Serbia, during the period from December 2020 to February 2021. All patients required mechanical ventilation and mortality rate was 100%. The goal of this study was to evaluate antibiotic resistance profiles and virulence potential of A. baumannii isolates recovered from patients with severe form of COVID-19 who had a need for mechanical ventilation. All tested A. baumannii isolates (n = 64) were sensitive to colistin, while resistant to meropenem, imipenem, gentamicin, tobramycin, and levofloxacin according to the broth microdilution method and MDR phenotype was confirmed. In all tested isolates, representatives of international clone 2 (IC2) classified by multiplex PCR for clonal lineage identification, bla _AmpC, bla _OXA-51, and bla _OXA-23 genes were present, as well as ISAba1 insertion sequence upstream of bla _OXA-23. Clonal distribution of one dominant strain was found, but individual strains showed phenotypic differences in the level of antibiotic resistance, biofilm formation, and binding to mucin and motility. According to PFGE, four isolates were sequenced and antibiotic resistance genes as well as virulence factors genes were analyzed in these genomes. The results of this study represent the first report on virulence potential of MDR A. baumannii from hospital in Serbia.

Keywords: AMR; Acinetobacter baumannii; COVID-19; ICU; virulence potential.

Figure 1

Schematic description of COVID-19 patient’s hospitalization at intensive care unit (ICU) and timepoints of Acinetobacter baumannii recovery. Arrows indicate the sequenced isolates.

Figure 2

Dendrogram derived from ApaI PFGE patterns showing the relatedness of Acinetobacter baumannii isolated from COVID-19 patients in Serbia.

Figure 3

Distribution of Acinetobacter baumannii biofilm producers recovered from different samples (blood, tip of the aspirator, tracheal aspirate, tip of the CVC, and sputum) from COVID-19 patients.

Figure 4

Mucin binding ability of Acinetobacter baumannii isolates originated from female and male COVID-19 patients; # denotes statistical significance.

Figure 5

Heat map demonstrating summarized virulence potential and antibiotic resistance of tested Acinetobacter baumannii isolates. Results were approximated on the relative scale ranging from 0 (blue) as the lowest values, progressing to white, then to 100 (red) as the highest values.