Molecular epidemiological characteristics of non-Acinetobacter baumannii in a three-A hospital in Guangzhou from 2013 to 2021

OBJECTIVE  To investigate the molecular epidemiological characteristics of non-Acinetobacter baumannii in a three-A hospital in Guangzhou from 2013 to 2021, including species distribution, drug resistance phenotype and genotype, characteristics of virulence gene and characteristics of genome structure.

METHODS  A total of 46 clinical isolates of non-A. baumannii strains at Guangdong General Hospital from 2013 to 2021 were analyzed. Drug susceptibility testing was performed with the disk diffusion method, and whole-genome sequencing was employed to predict resistance genes and virulence genes, and conduct pan-genome analysis.

RESULTS  Among the 46 non-A. baumannii strains, four species were identified, with Acinetobacter pittii （28 strains, 60.87%） and Acinetobacter nosocomialis （16 strains, 34.78%） being the predominant species. One strain each of Acinetobacter haemolyticus and Acinetobacter seifertii was detected （2.17% each）. Non-A. baumannii strains exhibited the most prominent drug resistance to cefepime, with a resistance rate of 21.74%, alongside a high intermediate resistance rate. Genomic analysis revealed abundant resistance genes （e.g., bla_OXA-417, bla_NDM-1） and virulence genes （primarily involved in iron uptake and biofilm formation）. Pan-genome analysis showed a low proportion of core genes （204）, indicating significant genomic divergence among the four species.

CONCLUSIONS  This study highlights the notable genetic diversity and reservoir of resistance genes in non-A. baumannii strains from this hospital, emphasizing the need for strengthening surveillance through molecular techniques to guide clinical infection prevention and control.