Dissemination of bla NDM-5 and mcr-8.1 in carbapenem-resistant Klebsiella pneumoniae and Klebsiella quasipneumoniae in an animal breeding area in Eastern China

Examining the presence of carbapenem resistant Enterobacterales and routes of transmission to bovine carcasses at slaughterhouses

This study was conducted to investigate the existence and possible transmission routes of CREs during the bovine slaughter process. A total of 600 samples including rectoanal mucosal swaps, bovine hides and carcasses were collected weekly, over a 20 week period from three different slaughterhouses in Samsun province and analyzed in terms of CRE. Isolation of CRE was performed using Chromatic CRE Agar. Obtained isolates were identified using PCR and VITEK MS. E-test method was used for screening of carbapenemase production and disk diffusion method was used for detection of phenotypic carbapenem resistance. Presence of five major carbapenemase genes were investigated by PCR and obtained amplicons were sequenced by Sanger sequencing. Clonal relatedness was investigated by Clermont phylo-typing and MLST. Plasmid incompability groups were determined by PCR-based replicon typing. Based on the results, only one bovine hide sample was found positive in terms of CRE and blaKPC-2 harbouring E. coli ST398 (phylogroup A) was identified. E. coli ST398 was found resistant to meropenem, imipenem, ertapenem, doripenem and also tested fluoroquinolones. ST398 was found to harbour three distinct replicons, namely N, FIIK, and FIB KQ. Inc. groups for these replicons were identified as IncN and IncFIIK. On the other hand, no concrete evidence has been obtained to suggest that CREs are spreading at the slaughterhouse level. Conclusively, conducting further studies in areas such as farms, pens, and feedlots is necessary to gain a better understanding of the transmission routes of CREs in livestock.

Microbiota Profiles of Hen Eggs from the Different Seasons and Different Sectors of Shanghai, China

Hen eggs are one of the most popular foods worldwide, and their safety is critical. Employing 16S rRNA full-length sequencing is an effective way to identify microorganisms on or in eggs. Here, hen eggs collected from poultry farms over four seasons, as well as from markets in Shanghai, were analyzed with third-generation sequencing. Firmicutes (44.46%) and Proteobacteria (35.78%) were the two dominant phyla, and Staphylococcus, Acinetobacter, Aerococcus, Psychrobacter, and Lactobacillus were the dominant genera. The dominant genera on the eggshell surfaces from the farms varied with the seasons, and the highest contamination of Staphylococcus (32.93%) was seen in the eggs collected during the summer. For the market samples, Pseudomonas was the most abundant in content, with Staphylococcus being the most-often genera found on the eggshell surfaces. Moreover, several potential pathogenic bacteria including Riemerella anatipestifer (species), Klebsiella (genus), and Escherichia/shigella (genus) were detected in the samples. The results revealed the impacts of weather on the microbiota deposited on an eggshell's surface, as well as the impacts due to the differences between the contents and the surface. The results can help disinfect eggs and guide antibiotic selection.

Mobile Colistin Resistance (mcr) Gene-Containing Organisms in Poultry Sector in Low- and Middle-Income Countries: Epidemiology, Characteristics, and One Health Control Strategies

Mobile colistin resistance (mcr) genes (mcr-1 to mcr-10) are plasmid-encoded genes that threaten the clinical utility of colistin (COL), one of the highest-priority critically important antibiotics (HP-CIAs) used to treat infections caused by multidrug-resistant and extensively drug-resistant bacteria in humans and animals. For more than six decades, COL has been used largely unregulated in the poultry sector in low- and middle-income countries (LMICs), and this has led to the development/spread of mcr gene-containing bacteria (MGCB). The prevalence rates of mcr-positive organisms from the poultry sector in LMICs between January 1970 and May 2023 range between 0.51% and 58.8%. Through horizontal gene transfer, conjugative plasmids possessing insertion sequences (ISs) (especially ISApl1), transposons (predominantly Tn6330), and integrons have enhanced the spread of mcr-1, mcr-2, mcr-3, mcr-4, mcr-5, mcr-7, mcr-8, mcr-9, and mcr-10 in the poultry sector in LMICs. These genes are harboured by Escherichia, Klebsiella, Proteus, Salmonella, Cronobacter, Citrobacter, Enterobacter, Shigella, Providencia, Aeromonas, Raoultella, Pseudomonas, and Acinetobacter species, belonging to diverse clones. The mcr-1, mcr-3, and mcr-10 genes have also been integrated into the chromosomes of these bacteria and are mobilizable by ISs and integrative conjugative elements. These bacteria often coexpress mcr with virulence genes and other genes conferring resistance to HP-CIAs, such as extended-spectrum cephalosporins, carbapenems, fosfomycin, fluoroquinolone, and tigecycline. The transmission routes and dynamics of MGCB from the poultry sector in LMICs within the One Health triad include contact with poultry birds, feed/drinking water, manure, poultry farmers and their farm workwear, farming equipment, the consumption and sale of contaminated poultry meat/egg and associated products, etc. The use of pre/probiotics and other non-antimicrobial alternatives in the raising of birds, the judicious use of non-critically important antibiotics for therapy, the banning of nontherapeutic COL use, improved vaccination, biosecurity, hand hygiene and sanitization, the development of rapid diagnostic test kits, and the intensified surveillance of mcr genes, among others, could effectively control the spread of MGCB from the poultry sector in LMICs.