Colistin and Carbapenem-Resistant Acinetobacter baumannii Aci46 in Thailand: Genome Analysis and Antibiotic Resistance Profiling

Abstract

Resistance to the last-line antibiotics against invasive Gram-negative bacterial infection is a rising concern in public health. Multidrug resistant (MDR) Acinetobacter baumannii Aci46 can resist colistin and carbapenems with a minimum inhibitory concentration of 512 µg/mL as determined by microdilution method and shows no zone of inhibition by disk diffusion method. These phenotypic characteristics prompted us to further investigate the genotypic characteristics of Aci46. Next generation sequencing was applied in this study to obtain whole genome data. We determined that Aci46 belongs to Pasture ST2 and is phylogenetically clustered with international clone (IC) II as the predominant strain in Thailand. Interestingly, Aci46 is identical to Oxford ST1962 that previously has never been isolated in Thailand. Two plasmids were identified (pAci46a and pAci46b), neither of which harbors any antibiotic resistance genes but pAci46a carries a conjugational system (type 4 secretion system or T4SS). Comparative genomics with other polymyxin and carbapenem-resistant A. baumannii strains (AC30 and R14) identified shared features such as CzcCBA, encoding a cobalt/zinc/cadmium efflux RND transporter, as well as a drug transporter with a possible role in colistin and/or carbapenem resistance in A. baumannii. Single nucleotide polymorphism (SNP) analyses against MDR ACICU strain showed three novel mutations i.e., Glu229Asp, Pro200Leu, and Ala138Thr, in the polymyxin resistance component, PmrB. Overall, this study focused on Aci46 whole genome data analysis, its correlation with antibiotic resistance phenotypes, and the presence of potential virulence associated factors.

Emergence of high colistin resistance in carbapenem resistant Acinetobacter baumannii in Pakistan and its potential management through immunomodulatory effect of an extract from Saussurea lappa

“…Particularly, there were two isolates detected with resistance to all tested antibiotics from two different hospitals. Also, the emergence of colistin resistance among carbapenem resistant isolates have been reported in other parts of the world (Abdulzahra et al, 2018;Al-Kadmy et al, 2019;Thadtapong et al, 2021). If the situation is not tackled vigilantly, the frequent outbreaks of pan-drug resistant strains of A. baumannii could be expected in the near future.…”

Engineering of lysin by fusion of antimicrobial peptide (cecropin A) enhances its antibacterial properties against multidrug-resistant Acinetobacter baumannii

“…Pathogens with resistance to three or more antimicrobial agents are called multidrug-resistant (MDR) bacteria that have recently become a major public health concern ( Li et al, 2015 ; Thadtapong et al, 2021 ). Acinetobacter species is hospital-oriented bacterial pathogens responsible for several epidemics worldwide ( Almasaudi, 2018 ).…”

Whole genome sequence of pan drug-resistant clinical isolate of Acinetobacter baumannii ST1890

“…Advances in whole-genome sequencing technology have facilitated bacterial whole-genome characterization, enhancing the ability to elucidate the antibiotic-resistant mechanism and pathogenesis in Acinetobacter baumannii [33,34]. However, data concerning genome analysis on colistin resistance of Acinetobacter baumannii isolated from Thailand is currently limited in the literature [35]. To understand the antibiotics-resistant mechanism and virulence factors in A. baumannii, we described the whole genome of PDR-A.…”