Spread of the florfenicol resistance floR gene among clinical Klebsiella pneumoniae isolates in China

Abstract

BackgroundFlorfenicol is a derivative of chloramphenicol that is used only for the treatment of animal diseases. A key resistance gene for florfenicol, floR, can spread among bacteria of the same and different species or genera through horizontal gene transfer. To analyze the potential transmission of resistance genes between animal and human pathogens, we investigated floR in Klebsiella pneumoniae isolates from patient samples. floR in human pathogens may originate from animal pathogens and would reflect the risk to human health of using antimicrobial agents in animals.MethodsPCR was used to identify floR-positive strains. The floR genes were cloned, and the minimum inhibitory concentrations (MICs) were determined to assess the relative resistance levels of the genes and strains. Sequencing and comparative genomics methods were used to analyze floR gene-related sequence structure as well as the molecular mechanism of resistance dissemination.ResultsOf the strains evaluated, 20.42% (67/328) were resistant to florfenicol, and 86.96% (20/23) of the floR-positive strains demonstrated high resistance to florfenicol with MICs ≥512 μg/mL. Conjugation experiments showed that transferrable plasmids carried the floR gene in three isolates. Sequencing analysis of a plasmid approximately 125 kb in size (pKP18–125) indicated that the floR gene was flanked by multiple copies of mobile genetic elements. Comparative genomics analysis of a 9-kb transposon-like fragment of pKP18–125 showed that an approximately 2-kb sequence encoding lysR-floR-virD2 was conserved in the majority (79.01%, 83/105) of floR sequences collected from NCBI nucleotide database. Interestingly, the most similar sequence was a 7-kb fragment of plasmid pEC012 from an Escherichia coli strain isolated from a chicken.ConclusionsIdentified on a transferable plasmid in the human pathogen K. pneumoniae, the floR gene may be disseminated through horizontal gene transfer from animal pathogens. Studies on the molecular mechanism of resistance gene dissemination in different bacterial species of animal origin could provide useful information for preventing or controlling the spread of resistance between animal and human pathogens.Electronic supplementary materialThe online version of this article (10.1186/s13756-018-0415-0) contains supplementary material, which is available to authorized users.

Identification of floR Variants Associated with Tn4371-Like Integrative and Conjugative Elements in Human Clinical Pseudomonas Aeruginosa Isolates

“…The positive rates were consistent with the abundance of the corresponding genes in the pooled genomic DNA sequencing libraries. The positive rate of the oR-T1 gene in the strains collected from 2015-2017 (7.39%, 17/230) was increased compared with that from 2008-2009 (3.00%, 6/200), which was also similar to the positive rate of the oR gene (7.01%, 23/328) of the human clinical K. pneumoniae isolates collected from the same district [5]. Zhan et al also reported a dramatic increase in orfenicol-resistant invasive nontyphoidal Salmonella (iNTS) in China between 2007 and 2016 [3].…”

“…However, due to the inappropriate use of orfenicol to prevent or cure bacterial infections, orfenicol resistance has become increasingly serious in veterinary medicine [2]. Although orfenicol is not approved for use in humans, an increasing number of studies have reported dramatic and serious orfenicol resistance in various clinical strains, such as Pasteurella multocida, Salmonella, and Klebsiella pneumoniae [3][4][5].…”

Occurrence and Antimicrobial Resistance Traits of Escherichia coli from Wild Birds and Rodents in Singapore

“…Both Phenicol resistance genes floR and cml1a that encode for efflux transporter [ 45 ] were detected in our study. The floR gene was reported in Klebsiella pneumoniae from clinical isolates [ 46 ] and E. coli from cattle [ 47 ], while cml1a was found in E. coli from poultry [ 48 ]. Another gene catA1 was found in isolate C1797, which encodes for an enzyme that inactivates Phenicols [ 45 ] and it was previously also reported in birds [ 43 ].…”

Live Feeds Used in the Larval Culture of Red Cusk Eel, Genypterus chilensis, Carry High Levels of Antimicrobial-Resistant Bacteria and Antibiotic-Resistance Genes (ARGs)

“…Finally, florfenicol-resistance-encoding genes, mainly floR, have frequently been associated with plasmids carried by human and animal pathogenic bacteria [85][86][87][88][89], thus the co-presence of this gene and plasmid elements in a high number of the studied isolates (71.2%) provides very favorable conditions for the genetic exchange among bacteria comprising the live feed and fish larval gut microbiota. This increases the feasibility of the spread of florfenicol-encoding genes to bacterial pathogens.…”