Epidemiological Analysis of Multidrug-Resistant Acinetobacter baumannii Isolates in a Tertiary Hospital Over a 12-Year Period in China

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.

Fitness Costs of Tigecycline Resistance in Acinetobacter baumannii and the Resistance Mechanism Revealed by a Transposon Mutation Library

“…Although tigecycline is regarded as the last resort for treating MDR and XDR A. baumannii infections, the tigecycline resistance rate has risen in recent years [ 23 , 42 , 43 , 44 ]. However, the underlying mechanism is still not well understood.…”

Origin, Phylogeny, and Transmission of the Epidemic Clone ST208 of Carbapenem-Resistant Acinetobacter baumannii on a Global Scale

“…In recent years, ST208 has become one of the predominant sequence types (STs) of carbapenem-non-susceptible isolates in China ( 10 – 12 ). Several outbreaks of MDR ST208 A. baumannii producing OXA-23-like carbapenemase have occurred ( 13 – 15 ), representing a serious public health threat. However, few studies have focused on evaluating the genetic background differences and worldwide dissemination of ST208 A. baumannii isolated from very distant geographic regions.…”

Untitled

“…Multidrug-resistant (MDR) bacteria are termed so because of their in vitro resistance to "more than one" antibiotic, and one of these serious bacteria that are showing this behavior is A. baumannii [9]. In the 1970s, this bacterium was sensitive to most known antibiotics, but nowadays, most A. baumannii are resistant [10,11]. The term "Iraqibacter" was used as a moniker for this resistant bacterium isolated from American soldiers in Iraq during 2003 [12].…”