First Report of Potentially Pathogenic Klebsiella pneumoniae from Serotype K2 in Mollusk Tegillarca granosa and Genetic Diversity of Klebsiella pneumoniae in 14 Species of Edible Aquatic Animals

Abstract

Klebsiella pneumoniae can cause serious pneumonitis in humans. The bacterium is also the common causative agent of hospital-acquired multidrug-resistant (MDR) infections. Here we for the first time reported the genetic diversity of K. pneumoniae strains in 14 species of edible aquatic animals sampled in the summer of 2018 and 2019 in Shanghai, China. Virulence-related genes were present in the K. pneumoniae strains (n = 94), including the entB (98.9%), mrkD (85.1%), fimH (50.0%), and ybtA (14.9%) strains. Resistance to sulfamethoxazole-trimethoprim was the most prevalent (52.1%), followed by chloramphenicol (31.9%), and tetracycline (27.7%), among the strains, wherein 34.0% had MDR phenotypes. Meanwhile, most strains were tolerant to heavy metals Cu2+ (96.8%), Cr3+ (96.8%), Zn2+ (91.5%), Pb2+ (89.4%), and Hg2+ (81.9%). Remarkably, a higher abundance of the bacterium was found in bottom-dwelling aquatic animals, among which mollusk Tegillarca granosa contained K. pneumoniae 8-2-5-4 isolate from serotype K2 (ST-2026). Genome features of the potentially pathogenic isolate were characterized. The enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR)–based genome fingerprinting classified the 94 K. pneumoniae strains into 76 ERIC genotypes with 63 singletons, demonstrating considerable genetic diversity in the strains. The findings of this study fill the gap in the risk assessment of K. pneumoniae in edible aquatic animals.

Environmental Compatibility and Genome Flexibility of Klebsiella oxytoca Isolated from Eight Species of Aquatic Animals

“…Multilocus sequence typing (MLST) analysis of the K. oxytoca isolates was performed on the seven conserved core genes (gapA, infB, mdh, pgi, phoE, rpoB, and tonB) in K. oxytoca against the MLST database (https://cge.food.dtu.dk/services/MLST/, accessed on 1 October 2023) [20]…”

“…Antibiotic susceptibility of the K. oxytoca isolates was determined according to the disco diffusion method approved by Clinical and Laboratory Standards Institute (CLSI, M100-S28, 2018, USA) [15,20]. Mueller-Hinton (MH) agar medium and antibiotic discs were purchased from OXOID, Basingstoke, UK [15,20]. Heavy metal tolerance of the K. oxytoca isolates was examined according to broth dilution testing (microdilution, CLSI) [15,20,21].…”

“…Mueller-Hinton (MH) agar medium and antibiotic discs were purchased from OXOID, Basingstoke, UK [15,20]. Heavy metal tolerance of the K. oxytoca isolates was examined according to broth dilution testing (microdilution, CLSI) [15,20,21]. CdCl 2 , CrCl 3 , CuCl 2 , HgCl 2 , MnCl 2 , NiCl 2 , PbCl 2 , and ZnCl 2 (3200-3.125 µg/mL, Analytical Reagent) were purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China.…”

“…CdCl 2 , CrCl 3 , CuCl 2 , HgCl 2 , MnCl 2 , NiCl 2 , PbCl 2 , and ZnCl 2 (3200-3.125 µg/mL, Analytical Reagent) were purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China. Escherichia coli ATCC25922 and K12 strains (Institute of Industrial Microbiology, Shanghai, China) were used as quality control strains [15,20,21].…”

“…To generate the phylogenomic tree, 1482 single-copy orthologues present in all the genomes were inferred using the OrthoFinder software (version 2.5. Multilocus sequence typing (MLST) analysis of the K. oxytoca isolates was performed on the seven conserved core genes (gapA, infB, mdh, pgi, phoE, rpoB, and tonB) in K. oxytoca against the MLST database (https://cge.food.dtu.dk/services/MLST/, accessed on 1 October 2023) [20]…”