Abstract
Acinetobacter baumannii is an important nosocomial pathogen, which is multidrug resistant (MDR). Acinetobacter baumannii has become a major threat to public health worldwide due to its ability to easily acquire resistant genes. In order to analyze its epidemiology characteristics and the genetic evolution, A. baumannii isolates obtained from a Chinese tertiary hospital in the past 12 years (2008–2019), 295 isolates of non-repetitive A. baumannii, were recovered from patients and wards environments. The resistance genes were analyzed using antimicrobial susceptibility testing. The genetic relatedness of 295 isolates was identified by multilocus sequence typing (MLST) and eBURST analysis. It was found that the antibiotic-resistant and carbapenemase-resistant genes of all the 295 MDR A. baumannii in the hospital have not changed significantly over the past 12 years; all of them were resistant to multiple antibiotics except the polymyxin E and tigecycline. The results of drug-resistant genes showed that the detection rates of carbapenemase-resistant genes blaOXA−23, blaTEM−1, and blaOXA−66 were 97.6, 75.3, and 71.9%, respectively, which were detected almost every year from 2008 to 2019. Additionally, 16s rRNA methylation enzyme gene armA, aminoglycoside-resistant gene ant(3")-I, and class I integrase gene could also have a high positive rate. By MLST, these isolates were assigned to 12 sequence types (STs), including ST369, ST208, ST195, ST191, ST368, ST530, ST469, ST451, ST229, ST381, ST543, and ST1176. eBURST analysis showed that 9 STs with ST208 as the founder genotype belonged to Group 1 except for ST229, ST530, and ST1176. Therefore, most MDR A. baumannii isolates had a relatively close genetic relationship. Notably, the predominant ST208 and ST369 at the early stage changed to ST451 in 2019, indicating that the complex and diverse genetic background of the prevalence of A. baumannii isolates in the hospital. Overall, further epidemiological surveillance and genetic evolution analysis of A. baumannii are required, which can provide new strategies for the prevention and control of A. baumannii infections.
Highlights
Acinetobacter baumannii, a Gram-negative and nonfermentative bacterium, is an important opportunist pathogen in hospitals
The sensitivity of all A. baumannii isolates recovered from 2008 to 2019 to 15 antimicrobial agents was shown in Table 3, all of them exhibited an multidrug resistance (MDR) phenotype, being resistant to three or more classes of antibiotics, such as amikacin, gentamicin, ceftazidime, ceftriaxone, piperacillin/tazobactam, imipenem, meropenem, levofloxacin, and ciprofloxacin, and the resistance of isolates to these drugs has not changed much over the past 12 years
All 295 MDR A. baumannii isolates were sensitive to polymyxin E, indicating that this antibiotic had a good therapeutic effect on A. baumannii in the hospital
Summary
Acinetobacter baumannii, a Gram-negative and nonfermentative bacterium, is an important opportunist pathogen in hospitals. It can cause a wide range of severe nosocomial infections, including ventilator-associated pneumonia, bloodstream infections, skin and soft tissue infections, wound infections, urinary tract infections, and meningitis [1]. Acinetobacter baumannii is found almost exclusively in the hospital environment; it can colonize the skin surface, respiratory tract, and digestive tract of patients [2]. Another concern for A. baumannii is the drug resistance. The World Health Organization (WHO) has assigned A. baumannii as a critical priority pathogen posing a great threat to public health, and toward which new antibiotics are urgently needed
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