Drug resistance of healthcare-associated pathogenic bacteria and carbapenem-resistant Acinetobacter baumannii homology in the general intensive care unit.

Background: The objective of this study was to understand the distribution and drug resistance of healthcare-associated infection (HAI) pathogens in an intensive care unit (ICU) of a general tertiary hospital in Inner Mongolia, and to classify carbapenem-resistant Acinetobacter baumannii (CR-AB) in ICU patients and environmental samples. Additionally, this study aimed to provide scientific evidence for the use of clinical antibiotics and effective prevention and control measures for CR-AB outbreak.

Methods: The distribution and drug resistance of pathogens isolated from patient's samples in the ICU of 12 Hospitals from January to May 2019 were retrospectively analyzed. Meanwhile, CR-AB isolated from patients and environmental samples were collected and classified by pulsed-field gel electrophoresis (PFGE).

Results: The pathogens isolated from ICU samples, mainly Gram-negative bacteria (63.07%), were CR-AB, Klebsiella pneumoniae, and Pseudomonas aeruginosa; the main Gram-positive bacteria (22.13%) were Enterococcus faecium and Staphylococcus aureus; and fungi accounted for the remaining (14.80%). The samples mainly came from sputum (41.09%). Among non-fermenting bacteria, the resistance rates of CRAB to piperacillin, piperacillin/tazobactam, and other treatments were higher than those of Pseudomonas aeruginosa (P<0.05). Meanwhile, the resistance rates to ampicillin/sulbactam and compound sulfamethoxazole were lower than those of Pseudomonas aeruginosa (P<0.05). The resistance rates of Klebsiella pneumoniae to piperacillin/tazobactam, ceftazidime, and others were higher than those of Escherichia coli (P<0.05). Among Gram-positive bacteria, the resistance rates of Enterococcus faecium to erythromycin, clindamycin, and other treatment were higher than those of Staphylococcus aureus (P<0.05). A total of 62 bands were obtained from 63 strains of CR-AB by electrophoresis. Also, 16 clusters (A-P) were obtained with a 74% similarity coefficient, among which K, L, and N types (more than 9 strains) were more common.

Conclusions: Gram-negative bacteria were the primary pathogens of HAI in the ICU, and their drug resistance was serious. There is homology in the PFGE typing of CR-AB. Therefore, hospitals should strengthen the surveillance of drug-resistant pathogenic bacteria. Additionally, further cleaning and disinfection measures are needed to improve environmental hygiene and prevent outbreaks of HAI.