Species identification, antibiotic resistance, and virulence in Enterobacter cloacae complex clinical isolates from South Korea

Abstract

This study aimed to identify the species of Enterobacter cloacae complex (ECC) isolates and compare the genotype, antibiotic resistance, and virulence among them. A total of 183 ECC isolates were collected from patients in eight hospitals in South Korea. Based on partial sequences of hsp60 and phylogenetic analysis, all ECC isolates were identified as nine species and six subspecies. Enterobacter hormaechei was the predominant species (47.0%), followed by Enterobacter kobei, Enterobacter asburiae, Enterobacter ludiwigii, and Enterobacter roggenkampii. Multilocus sequence typing analysis revealed that dissemination was not limited to a few clones, but E. hormaechei subsp. xiangfangensis, E. hormaechei subsp. steigerwaltii, and E. ludwigii formed large clonal complexes. Antibiotic resistance rates were different between the ECC species. In particular, E. asburiae, E. kobei, E. roggenkampii, and E. cloacae isolates were highly resistant to colistin, whereas most E. hormaechei and E. ludwigii isolates were susceptible to colistin. Virulence was evaluated through serum bactericidal assay and the Galleria mellonella larvae infection model. Consistency in the results between the serum resistance and the G. mellonella larvae infection assay was observed. Serum bactericidal assay showed that E. hormaechei, E. kobei, and E. ludwigii were significantly more virulent than E. asburiae and E. roggenkampii. In this study, we identified the predominant ECC species in South Korea and observed the differences in antibiotic resistance and virulence between the species. Our findings suggest that correct species identification, as well as continuous monitoring is crucial in clinical settings.

Carbapenem-Resistant Enterobacter cloacae Complex in Southwest China: Molecular Characteristics and Risk Factors Caused by NDM Producers

“…In this study, we classified the 20 CREC strains involved using the latest described method. 2 Our research discovered that Enterobacter hormaechei was the predominant strain, with Enterobacter hormaechei subsp. xiangfangensis being the major representative, which was consistent with the findings of the majority of other studies.…”

“…1 ECC comprises various species including Enterobacter cloacae, Enterobacter hormaechei, Enterobacter asburiae, Enterobacter kobei, Enterobacter ludwigii, Enterobacter nimipressuralis, Enterobacter mori, among others. 2 The hsp60 gene typing scheme serves as a common method for distinguishing members within ECC, and it is widely adopted in practice. 3 ECC strains are notorious members of the "ESKAPE" pathogens, causing diverse infections in clinical settings such as pulmonary, urinary system, and bloodstream infections.…”

Isolation and draft genome sequence of Enterobacter asburiae strain i6 amenable to genetic manipulation

“…Among the ECC, E. cloacae and E. hormaechei are the most frequently isolated species in clinical infections, especially in immunocompromised patients and those admitted to intensive care units 37 , whereas E. asburiae had lower survival rates against serum than E. cloacae, E. hormaechei , and E. ludwigii isolates 4 . In this report, the E. asburiae i6 genome unexpectedly exhibited most, if not all, of the genetic features of PGPB previously reported in Enterobater sp.…”

“…The Enterobacter cloacae complex (ECC) is a group of common opportunistic pathogens consisting of Enterobacter asburiae, Enterobacter cloacae, Enterobacter hormaechei, Enterobacter kobei, Enterobacter ludwigii, Enterobacter mori, and Enterobacter nimipressuralis . In addition, recently identified species, including Enterobacter roggenkampii, Enterobacter chengduensis , and Enterobacter bugandensis , are clustered with the ECC species 4 . While E. asburiae , as a part of ECC, is considered to be an opportunistic pathogen, not only E. asburiae but also some of Enterobacter genus have been reported as plant growth-promoting bacteria (PGPB).…”

Phenotypic and genomic insights into the pathogenicity and antimicrobial resistance of an Enterobacter roggenkampii strain isolated from diseased silver arowana (Osteoglossum bicirrhosum)

“…Enterobacter roggenkampii can cause infections in various hosts, such as humans (Wang, Feng, et al, 2020;Wang, Zhao, et al, 2020), chickens (Lei et al, 2020), dogs (Sato et al, 2021), and plants (Guo et al, 2020;Zhou et al, 2021). However, E. roggenkampii have often been reported to cause host infection together with E. cloacae complex (ECC) (Bolourchi et al, 2022;Feng et al, 2021;Fukuzawa et al, 2023;Ganbold et al, 2023;Girlich et al, 2021;Ji et al, 2021;Sarangi et al, 2022). There are few studies on the causes of host infection caused by only E. roggenkampii and have been no reported cases of E. roggenkampii infection in aquatic animals at present.…”