First Isolation and Characterization of Chryseobacterium cucumeris SKNUCL01, Isolated from Diseased Pond loach (Misgurnus anguillicaudatus) in Korea

Abstract

Loaches are widely distributed throughout the natural environment and are consumed for medicinal purposes in East Asia. Usually, loaches are cultured in ponds where the water conditions can easily cause bacterial infections. Infections due to bacterial pathogens such as Aeromonas have been well described in cultured loaches; however, there is no report regarding Chryseobacterium infection. This study focused on the elucidation of the pathogenic and antibiotic resistance characteristics of C. cucumeris, SKNUCL01, isolated from diseased loaches (Misgurnus anguillicaudatus). SKNUCL01 forms a biofilm, which is associated with its virulence. Koch’s postulates were satisfied with a lethal dose 50 (LD50) of 8.52 × 107 colony-forming units (CFU)/ml. Abrasion facilitates the mortality of the fish, which makes it a possible infection route for C. cucumeris. The strain showed resistance to nearly all tested antibiotics, such as trimethoprim/sulfamethoxazole, levofloxacin, and ciprofloxacin, formerly considered effective treatments. Phenotypic analyses for antibiotic resistance—the combined disk test, double-disk synergy test, modified Hodge test, and efflux pump inhibition test—revealed that the resistance of SKNUCL01 originated from metallo-beta lactamases (MBLs) and efflux pumps. Our findings provide evidence that could result in a breakthrough against multidrug-resistant Chryseobacterium infection in the aquaculture industry; the antibiotic resistance-related genes can be elucidated through future study.

The Opportunistic Pathogen Chryseobacterium balustinum WLT: Pathogenicity and Antibiotic Resistance

“…In the case of the present study, the pathogenesis of Chryseobacterium was presumed to proceed from a localized to a systemic infection. It was also observed in our previous report with C. cucumeris [32]. Furthermore, considering the production of proteolytic enzymes, including esterase, the zoonotic potential of C. balustinum through infection through the skin should not be excluded.…”

“…Since, Chryseobacterium sp. has been recognized as an emerging fish pathogen in South Korea in recent times, studies regarding antibiotic susceptibility-based treatment methods should precede [32,37]. In a previous Chryseobacterium infection case study, we failed to cure the diseased fish and we speculated that high prevalence of antibiotic resistance by Chryseobacterium was a reason.…”

“…Generally, the pathogenicity of Chryseobacterium in farmed fish is comparably lower than the major bacterial pathogens (e.g., Flavobacterium and Lactococcus) and earlier studies reported 5 LogCFU/fish as the median lethal dose of Chryseobacterium [33,34]. The LD50 of C. cucumeris in pond loach was 7.8 LogCFU/fish [32], whereas the LD50 of C. indologenes in yellow perch was 8.1 LogCFU/fish [35]. The C. scophthalmum TPBLGL 18 infection in golden mahseer resulted in median lethal dose of 6.2 LogCFU/fish [36].…”

Characterization of Potential Virulence, Resistance to Antibiotics and Heavy Metals, and Biofilm-Forming Capabilities of Soil Lignocellulolytic Bacteria

“…MKAL5 displayed moderate ability. Many investigators revealed the biofilm-forming ability of these bacteria species [Esteban and García-Coca, 2018;Kim et al, 2020;Bostanghadiri et al, 2021;Sornchuer et al, 2022]. Bacillus sp.…”

Prolongation of Fate of Bacteriophages In Vivo by Polylactic-Co-Glycolic-Acid/Alginate-Composite Encapsulation

“…Before collecting samples from the animals, either anesthesia was induced or euthanasia was performed with tricaine mesylate, as described previously [ 26 ]. Blood was collected from the caudal vein, and the spleen was collected from the aseptically opened peritoneal cavity.…”