Abstract
This study aims to characterize antimicrobial resistance (AMR) of all the non-duplicated Acinetobacter baumannii strains isolated from an intensive care unit in a tertiary hospital during the period of January 1 to December 31, 2015. A. baumannii (n = 95 strains) isolated from patients was subjected to antimicrobial susceptibility test (AST) by Vitek 2 Compact system to determine minimum inhibitory concentrations, followed by genotyping by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). Resistance genes of interest were PCR amplified and sequenced. All isolates were qualified as MDR, with a resistance rate of > 80% to 8 antimicrobials tested. In terms of beta-lactamase detection, the blaOXA23, blaTEM-1, and armA genes were detected frequently at 92.63%, 9 1.58%, and 88.42%, respectively. The metallo-β-lactamase genes blaIMP and blaVIM were undetected. Aph (3')-I was detected in 82 isolates (86.32%), making it the most prevalent aminoglycoside-modifying enzyme (AMEs) encoding gene. In addition, ant (3″)-I was detected at 30.53%, while 26.32% of the strains harbored an aac (6')-Ib gene. ERIC-PCR typing suggested moderate genetic diversity among the isolates, which might be organized into 10 distinct clusters, with cluster A (n = 86 isolates or 90.53%) being the dominant cluster. All of the A. baumannii strains detected in the ICU were MDR clones exhibiting extremely high resistance to carbapenems and aminoglycosides as monitored throughout the study period. They principally belonged to a single cluster of isolates carrying blaOXA23 and armA co-producing different AMEs genes.
Highlights
Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen adept at colonizing and thriving in the hospital environment
By virtue of its extraordinary aptitude to survive in the hospital environment and to develop extremely high resistance to an array of common antibiotics including aminoglycoside and carbapenem classes of antibiotics, A. baumannii has become a major challenge to medical care at the intensive care units (ICUs) (Shimose LA et al 2016; Molter G et al 2016; Shamsizadeh Z et al 2017)
We found that the isolates (n = 95) generally exhibited very high resistance to most of the commonly used clinical antibiotics including aminoglycosides and carbapenems, carried blaOXA23, blaTEM-1 and aph (3’)-I as major resistance genes and consisted mostly of strains belonging to a single dominant cluster (Cluster A in ERIC-PCR analysis)
Summary
Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen adept at colonizing and thriving in the hospital environment. Carbapenemase-producing multidrug resistant (MDR) A. baumannii has emerged as a prominent cause of healthcare-associated infections (HAIs) notably at intensive care units (ICUs), whose incidence seems to be ascending alarmingly in parts of China (He C et al 2011; Li Y et al 2018; Mariana Bitrian et al 2012; Behdad R et al 2020). By virtue of its extraordinary aptitude to survive in the hospital environment and to develop extremely high resistance to an array of common antibiotics including aminoglycoside and carbapenem classes of antibiotics, A. baumannii has become a major challenge to medical care at the ICU (Shimose LA et al 2016; Molter G et al 2016; Shamsizadeh Z et al 2017). Analysis on genomic relatedness among clinical isolates is necessary for determining an epidemic strain, as a first step toward informed diagnosis and anti-infective countermeasures
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