Journal Article

Molecular Detection of Carbapenemases in Acinetobacter baumannii Strains of Portugal and Association With Sequence Types, Capsular Types, and Virulence

Saavedra, Maria José, Almeida, Carina, Oliveira, Hugo, Franz, Charles M.A.P., Araújo, Daniela, Domingues, Rita, Cho, Gyu-Sung, Oliveira, Ricardo, Azeredo, Joana, Silva, Sónia

2024

Overview

•In a longitudinal study of carbapenem-resistant Acinetobacter baumannii strains of Portugal conducted (n = 26, 2005–2019), a clear increase in antimicrobial resistance profile was observed over the years, explaining in part the successful dominance of specific clones.•There is a low diversity of capsule types (KL7 > KL2 > KL120 > KL9, ordered by decreasing prevalence), among >120 KL types available in A baumannii, with different virulence.•Correlations between OXA genes with specific sequence type (ST)/KL types were identified (eg, OXA-40-like/ST46Past/KL9 or KL120 and OXA-23-like/ST2Past/KL2).•Clonal shifts of carbapenem-resistant Acinetobacter baumannii (OXA-40-like/ST46 in 2005 and OXA-23-like/ST2 in 2006–2019) were observed. Particular KL shifts (KL2, KL7, and KL9) within ST2 (or clonal complex II) were also found, potentially favoring its adaptation and worldwide global dominance. Carbapenem-resistant Acinetobacter baumannii (CRAB) is an important nosocomial pathogen. The capsular type (K-type) is considered a major virulence factor, contributing to the evasion of host defenses. The global spread and dissemination dynamics between K-types, sequence types (ST), antibiotic resistance genes, and virulence factors remain largely unknown in Portugal. A collection of 96 CRAB clinical samples collected between 2005 and 2019 in the northern region of Portugal were tested for antimicrobial susceptibility profile and screened by polymerase chain reaction for resistance genetic determinants. A subset of 26 representative isolates was subjected to whole-genome sequencing to assess K types, ST types, and genomic relatedness. The pathogenicity of distinct K-types was also tested using Galleria mellonella model. For the 96 CRAB isolates analyzed, high antimicrobial resistance (>90%) was observed to the carbapenems, fluoroquinolones, and miscellaneous agents. Greater antimicrobial susceptibility (∼30%–57%) was observed for aminoglycosides, particularly tobramycin, and amikacin. Genotypically, 75 strains (78.5%) carried blaOXA-23-like, 18 strains (18.8%) carried blaIMP-like, and 11 strains (14.9%) carried blaOXA-40-like carbapenem resistance genes, respectively. Associations between OXA and ST/capsular locus (KL) types were observed over the years (eg, OXA-40-like/ST46Past/KL120 and OXA-23-like/ST2Past/KL2). ST2Past of clonal complex II was present in most strains, a dominant drug-resistant lineage in the United States and Europe. KL7 was also the most prevalent KL-type (38.5%), followed by KL2 (34.6%), KL120 (23.1%), and KL9 (3.8%). Virulence assessment for different K-types in a Galleria mellonella model revealed a significantly increased virulence for KL120 when compared with KL7, KL9, and KL2. There are specific CRAB serotypes circulating in Portugal, accounting by the low diversity of acquired carbapenemase genes (OXA-23-like and OXA-40-like), ST types (ST2 and ST46) and KL types (KL2, KL7, KL9, and KL120) identified. The high prevalent of ST2, especially when associated with KL2 and blaOXA-23-like, suggest that antibiotic resistance has been driven by clonal expansion of clonal complex II. Such findings provide useful information on the diversity of multidrug-resistant bacterium that might be relevant for antibacterial interventions.

• Publisher: Elsevier Inc,Elsevier Limited
• Subject: Acinetobacter baumannii / Acinetobacter baumannii - drug effects / Acinetobacter baumannii - enzymology / Acinetobacter baumannii - genetics / Acinetobacter baumannii - isolation & purification / Acinetobacter baumannii - pathogenicity / Acinetobacter Infections - drug therapy / Acinetobacter Infections - epidemiology / Acinetobacter Infections - microbiology / Amikacin / Animals / Anti-Bacterial Agents - pharmacology / Antibiotic resistance / Antibiotics / Antimicrobial agents / Antimicrobial resistance / Bacterial Proteins - genetics / beta-Lactamases - genetics / Biosynthesis / Capsular type / Carbapenem resistance / Carbapenemase / Carbapenems / Carbapenems - pharmacology / Drug resistance / Drug Resistance, Multiple, Bacterial - genetics / Epidemiology / Fluoroquinolones / Galleria mellonella / Genes / Genomes / Humans / Immune system / Infections / Intensive care / Internal Medicine / Microbial Sensitivity Tests / Moths - microbiology / Multidrug resistance / Nucleotide sequence / Pathogenicity / Pathogens / Phylogenetics / Portugal - epidemiology / Proteins / Public health / Sequence type / Serotypes / Strains (organisms) / Tobramycin / Virulence / Virulence - genetics / Virulence factors / Virulence Factors - genetics / Whole Genome Sequencing