An Outbreak of tet(X6)-Carrying Tigecycline-Resistant Acinetobacter baumannii Isolates with a New Capsular Type at a Hospital in Taiwan

Abstract

Dissemination of multidrug-resistant, particularly tigecycline-resistant, Acinetobacter baumannii is of critical importance, as tigecycline is considered a last-line antibiotic. Acquisition of tet(X), a tigecycline-inactivating enzyme mostly found in strains of animal origin, imparts tigecycline resistance to A. baumannii. Herein, we investigated the presence of tet(X) variants among 228 tigecycline-non-susceptible A. baumannii isolates from patients at a Taiwanese hospital via polymerase chain reaction using a newly designed universal primer pair. Seven strains (3%) carrying tet(X)-like genes were subjected to whole genome sequencing, revealing high DNA identity. Phylogenetic analysis based on the PFGE profile clustered the seven strains in a clade, which were thus considered outbreak strains. These strains, which were found to co-harbor the chromosome-encoded tet(X6) and the plasmid-encoded blaOXA-72 genes, showed a distinct genotype with an uncommon sequence type (Oxford ST793/Pasteur ST723) and a new capsular type (KL129). In conclusion, we identified an outbreak clone co-carrying tet(X6) and blaOXA-72 among a group of clinical A. baumannii isolates in Taiwan. To the best of our knowledge, this is the first description of tet(X6) in humans and the first report of a tet(X)-like gene in Taiwan. These findings identify the risk for the spread of tet(X6)-carrying tigecycline- and carbapenem-resistant A. baumannii in human healthcare settings.

Acinetobacter baumannii : Pathogenesis, virulence factors, novel therapeutic options and mechanisms of resistance to antimicrobial agents with emphasis on tigecycline

“…53 Recently co-exictence of tet(X6) and bla OXA-72 , located on chromosome and plasmid respectively, have been reported in A. baumannii clinical isolates. 54 Another suggested mechanism involved in tigecycline resistance is an outer membrane protein, AbuO, that is homologe of TolC.…”

Mobile Tigecycline Resistance: An Emerging Health Catastrophe Requiring Urgent One Health Global Intervention

“…Ecological niches in which plasmid-encoded TIG resistance tet (X) genes have been detected are shown in Table 1 . Clearly, there is increasing evidence of plasmid-encoded TIG resistance tet (X) genes reported in countries across Europe, Asia, United States, South America, and Africa involving humans, food animals, including chickens, pigs, ducks, pigeons, geese, and cattle, as well as companion animals, food animal products (meats), aquaculture and environment such as soil, livestock-farm water, wastewaters, sewages, and wildlife as reservoirs of MTR ( Bai et al, 2019 ; Chen et al, 2019a , b , 2020 , 2021 ; He et al, 2019 ; Sun C. et al, 2019 , 2020 ; Sun J. et al, 2019 ; Cao et al, 2020 ; Cui et al, 2020 , 2021b ; Ding et al, 2020 ; Du et al, 2020 ; He T. et al, 2020 ; Li et al, 2020 , 2021f ; Ma et al, 2020 ; Pan et al, 2020 ; Ruan et al, 2020 ; Song et al, 2020 ; Wang et al, 2020a , b ; Zhang et al, 2020b , 2021 ; Zheng et al, 2020 ; Cheng et al, 2021a , b ; Feng et al, 2021 ; Hirabayashi et al, 2021a , b ; Hsieh et al, 2021 ; Li et al, 2021e , f ; Lu et al, 2021 ; Marathe et al, 2021 ; Martelli et al, 2021 ; Mohsin et al, 2021 ; Soliman et al, 2021 ; Sun et al, 2021a , b ; Tang et al, 2021 ; Wang et al, 2021f , g ; Xu et al, 2021 ; Yu Y. et al, 2021 ; Wu et al, 2022 ; Zhai et al, 2022 ). We further demonstrate this, through the specific reservoirs in which plasmid-borne transmissible tet (X) and tmexCD-toprJ genes have been detected as shown in Table 2 .…”

“…In essence, those in contact with animals (including veterinarians) are potential disseminators of MTR gene-containing organism into the public and veterinary hospital environments where these organisms have become a major nosocomial threat. Unfortunately, the organisms in ESKAPE ( Enterobacter , Staphylococcus , Klebsiella , Acinetobacter , Pseudomonas aeruginosa , and Escherichia coli ) group which are the most troubling pathogens associated with nosocomial and community infections worldwide ( De Oliveira et al, 2020 ), have been reported as traffickers of MTR genes ( He et al, 2019 ; Wang et al, 2019 ; Cui et al, 2020 ; Hsieh et al, 2021 ). However, the transmission of MTR at the human-animal interface is of more concern in developing countries because humans, especially those in rural areas, live in close contact with livestock ( Alonso et al, 2017 ).…”

“…Finally, there is an urgent need for countries to improve on their antimicrobial stewardship emphasizing massive education of the stakeholders in human and animal medicine (physicians, veterinarians and allied health workers, policy makers, and clinical microbiologists) and the public, on the dangers associated with MTR as well as basic IPC practices like hand hygiene (which breaks transmission cycle of resistant organisms/pathogens), and environmental sanitation ( Wan et al, 2021 ). It is also crucial to lay emphasis on prompt/adequate diagnosis and antimicrobial susceptibility testing as some of the isolates in this review showed susceptibility to some available antibiotics ( Hsieh et al, 2021 ).…”

“…Yes Bai et al, 2019;Chen et al, 2019aChen et al, ,b, 2021He et al, 2019;Sun J. et al, 2019;Cao et al, 2020;Chen et al, 2020;Cui et al, 2020;Du et al, 2020;He T. et al, 2020;Li et al, 2020;Ma et al, 2020;Pan et al, 2020;Ruan et al, 2020;Song et al, 2020;Wang et al, 2020a,b;Zhang et al, 2020a,b;Zheng et al, 2020;Cheng et al, 2021a,b;Cui et al, 2021b;Feng et al, 2021;Li et al, 2021a,c,d,e,f;Lu et al, 2021;Sun et al, 2021a,b;Tang et al, 2021;Wang et al, 2021c,f,g;Xu et al, 2021Zhang et al, 2021;Wu et al, 2022; Wang et al, 2019Wang et al, , 2020aChen et al, 2020;Ding et al, 2020;Pan et al, 2020;Zhang et al, 2020a;Cui et al, 2021b;Hsieh et al, 2021;Li et al, 2021a,b;Zeng et al, 2021…”