Outbreak of carbapenem-resistant Acinetobacter baumannii carrying the carbapenemase OXA-23 in ICU of the eastern Heilongjiang Province, China

Background: To investigate the carbapenem resistance mechanisms and clonal relationship of carbapenem-resistant Acinetobacter baumannii (CRAB) strains isolated in the intensive care unit (ICU) of the First Affiliated Hospital of Jiamusi University, management approaches to ICU clonal CRAB outbreaks were described. Methods: The sensitivity of the antibiotic was determined using the VITEK-2 automated system. Carbapenemase genes (bla(TEM), bla(SHV), bla(KPC), bla(NDM), bla(IMP-4), bla(VIM), bla(OXA-23), bla(OXA-24), bla(OXA-51), and bla(OXA-58)), AmpC enzyme genes (bla(ACC), bla(DHA), bla(ADC)), and ISAba1 were assessed for all collected isolates using polymerase chain reaction (PCR). The transfer of resistance genes was investigated via conjugation experiments. The clonal relationship of isolates was determined via enterobacterial repetitive intergenic consensus (ERIC)-PCR and multilocus sequence typing (MLST). When the detection rate of CRAB increased from 25% in 2010 to 92% in 2014, a number of actions were initiated, including enhanced infection control, staff education, and the cleaning of the hospital environment. Results: Clinical isolates were positive for the following genes: bla(OXA23), bla(OXA51), bla(OXA24), bla(ADC), bla(TEM), ISAba1, ISA-23, and ISA-ADC; however, bla(OXA58), ISA-51, bla(NDM), bla(IMP), bla(KPC), bla(TEM), bla(SHV), bla(VIM), and bla(ACC) were not detected. Four carbapenem-resistant isolates successfully transferred plasmids from A. baumannii isolates to E. coli J53. MLST showed that all strains belonged to ST2 except for one isolate, which belonged to the new genotype ST1199. The ERIC-PCR method found the following three genotypes: type A in 8, type B in 12, type C in 1, and two profiles (A, B) belonged to ST2. After taking control measures, the prevalence of CRAB isolates decreased, and the discovery rate of CRAB dropped to 11.4% in 2017. Conclusion: The obtained result suggests that bla(OXA-23)-producing CC2 isolates were prevalent in the ICU of the First Affiliated Hospital of Jiamusi University. Targeted surveillance was implemented to identify the current situation of the ICU and the further implementation of infection control effectively prevented the spread of nosocomial infection.