Study on molecular epidemiology of carbapenem-resistant Acinetobacter baumannii in different ICUs

Abstract

Objective To investigate the molecular epidemiology of carbapenem-resistant Acinetobacter baumannii (CRAB) in different ICUs of Renmin Hospital of Wuhan University. Methods The CRAB was collected from March 2017 to February 2018. The homology was tested by multi-site sequence typing (MLST); the disinfectant resistance gene qac △E1 was detected by PCR. The minimum inhibitory concentration (MIC) of chlorine tablets, benzalkonium bromide (BB) and chlorhexidine gluconate (CLX) on CRAB in different ICUs was determined and compared. Results Totally 82 strains of CRAB were divided into 8 sequence types (STs) containing ST540 (36.58%, 30/82), ST195 (21.95%, 18/82), ST208 (18.29%, 15/82), ST191(13.41%, 11/82), ST369 (4.88%, 4/82), ST469 (2.44%, 2/82), ST381 (1.22%, 1/82) and ST136 (1.22%, 1/82), and no new ST was found. All STs were found to be the clonal complex 92. The positive rate of qac△E1 gene was 76.83% (63/82); the MIC distribution of BB and CLX between qac△E1 genes of positive and negative isolates all showed no significant differences (H = 0.413, P = 0.680; H = 0.662, P = 0.508). The MIC of 82 strains of CRAB to chlorine tablets was 250 mg/L, that to BB ranged from 32 to 128 mg/L, and that to CLX ranged from 0.001 9% to 0.007 8%. The MIC of 41 strains (50%) of CRAB to BB and CLX was 64 mg/L and 0.003 9%, respectively, that of 2 strains (2.43%) of CRAB to BB was 128 mg/L, and that of 24 strains (29.26%) of CRAB to CLX was 0.007 8%. Meanwhile, the MIC distribution of BB and CLX in respiratory ICU, neurology ICU, neurosurgery ICU, cardiovascular surgery ICU and critical care medicine all showed no significant differences (H = 1.680, P = 0.794; H = 1.341, P = 0.719). Conclusion There is a widespread epidemic of the clonal complex 92 in ICUs in all departments of our hospital, and the CRAB is generally more resistant to common disinfectants than sensitive strains. Key words: Acinetobacter; Carbapenem; Drug resistance, bacterial