Comprehensive genomic analysis and characterization of a new ST 174 type Klebsiella variicola strain isolated from chicken embryos

Antioxidant and antibacterial coconut mesocarp polyphenol hydrogel dressing based on PVA/quaternary chitosan/sodium alginate with β-glycerophosphate

This study developed PQSp wound dressing hydrogels (S0-S6) using polyvinyl alcohol (PVA), quaternary chitosan (QCS), and sodium alginate (SA) as the matrix, with the addition of coconut mesocarp polyphenol (P-CTP, 0.1 %, 0.5 %, and 1.0 %) and β-glycerophosphate disodium (GP, 1.0 %) through a freeze-thaw method. Compared to hydrogels without P-CTP and GP (S0), the tensile strength of S1-S6 increased from 0.08 MPa to 0.45 MPa, elongation at break improved from 200 % to 320 %, and the swelling ratio decreased from 186 % to 82 % due to the effects of P-CTP and GP, while maintaining water content above 80 %, ensuring a moist environment for wound healing. Their thermal stability was also improved. SEM, FTIR, and XPS results confirmed enhanced crosslinking within the multi-network of the hydrogels, attributed to the increased hydrogen bonding from GP and P-CTP, independent of chemical crosslinking. However, antioxidant and antibacterial activities were dose-dependent only on P-CTP, with S3 and S6 showing the best effects. CAM and chicken embryo assays confirmed the hydrogels' non-toxicity and biocompatibility. These findings suggest that PQSp hydrogels, with their excellent mechanical properties, bioactivity, and safety, hold great potential for advanced wound dressing applications and provide a reference for expanding the application range of P-CTP.

Hypermucoviscous Multidrug-Resistant Klebsiella variicola Strain LL2208 Isolated from Chinese Longsnout Catfish (Leiocassis longirostris): Highly Similar to Human K. variicola Strains

Outbreaks of bacterial diseases occur in farmed Chinese longsnout catfish (Leiocassis longirostris). Due to limited information on aquatic Klebsiella variicola-infected animals, this study aimed to identify strain LL2208 isolated from diseased L. longirostris, determine its biological features, and evaluate its risk to public health. Strain LL2208 was tested for molecular identification, challenge, string, biofilm formation, and antimicrobial susceptibility. Furthermore, the whole genome of the strain was sequenced and analyzed. Based on molecular identification, strain LL2208 was identified as K. variicola. Artificial infection showed that this strain was moderately virulent to L. longirostris with an LD50 = 7.92 × 107 CFU/mL. Antibiotic sensitivity tests showed that this strain was resistant to penicillins, macrolides, aminoglycosides, amphenicols, glycopeptides, and lincosamide, indicating multidrug resistance. Strain LL2208 has a genome size of 5,557,050 bp, with a GC content of 57.38%, harboring 30 antimicrobial resistance genes and numerous virulence-related genes. Its molecular type was ST595-KL16-O5. Collinearity analysis showed that strain LL2208 was highly similar to the human-derived K. variicola strain. In conclusion, the multidrug-resistant and virulent K. variicola strain LL2208 was isolated from fish and may have originated from humans. These results provide a foundation for further studies on the transmission of K. variicola between humans and aquatic animals.

Comamonas testosteroni as the cause of mortality in embryonated chicken eggs of breeding broiler hens in Costa Rica

Mortality of chicken embryos and first-week chickens was reported in a commercial incubator company in Costa Rica. Six 1-day-old Cobb chickens and twenty-four embryonated chicken eggs were examined in the Laboratory of Avian Pathology and the Laboratory of Bacteriology of the National University of Costa Rica. Twelve dead-in-shell embryos showed maceration and were immersed in a putrid, turbid, slightly thick brown liquid. Additionally, the other 12 embryonated eggs had milky yellow-orange content. The livers of those embryos had congestion, haemorrhages and multifocal cream foci of necrosis. Granulocytic infiltration was observed in the bursa of Fabricius, myocardium, liver, lung and kidney. Livers and egg yolks from six embryonated chickens and all 1-day-old chickens were aseptically collected and cultured. In addition, tissues from six better conserved embryos and all 1-day-old chickens were fixed in buffered formalin and embedded in paraffin. Biochemical and molecular tests identified Comamonas testosteroni as the cause of the early, middle and late embryo mortality. As all the eggshells from the sampled embryonated eggs were dirty with soiled a fecal matter, contamination after manipulating the eggs was considered the source of infection. C. testosteroni is an environmental microorganism that has rarely been reported to cause human disease. To our knowledge, this is the first report of C. testosteroni causing mortality in a hatchery. Cleaning and disinfection using ozone were implemented in the hatchery to eliminate the embryo mortality associated with C. testosteroni.

Integrated analysis of noncoding RNAs and mRNAs reveals their potential roles in chicken spleen response to Klebsiella variicola infection

Klebsiella variicola is an emerging pathogen that has become a threat to human and animal health. There is evidence that long noncoding RNAs (lncRNAs) are involved in a host cell's response to microbial infections. However, no study has defined the link between K. variicola pathogenesis and lncRNAs until now. We used RNA sequencing to comprehensively analyze the lncRNAs and mRNAs in the chicken spleen after K. variicola infection. In total, we identified 2896 differentially expressed mRNAs and 578 differentially expressed lncRNAs. To examine the potential functions of these lncRNAs, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes signaling pathway enrichment analyses were performed on the target mRNAs of these differently expressed lncRNAs. The results suggested that lncRNAs play essential roles in modulating mRNA expression and triggering downstream immune signaling pathways to regulate the immune response in the chicken spleen. Using previous microRNA sequencing data, we constructed lncRNA-miRNA-mRNA regulatory networks to clarify the regulatory mechanisms in the chicken immune system. Several potential regulatory pairs related to K. variicola infection were found, involving XR_001467769.2, TCONS_00018386, gga-miR-132a-3p, gga-miR-132b-5p, gga-miR-2954, and novel62_mature. In conclusion, our findings make a significant contribution towards understanding the role of lncRNA in chicken spleen cells during K. variicola infection, thereby establishing a solid foundation for future research in this area.

Prevalence and Characterization of Salmonella Isolated from Chickens in Anhui, China

Salmonella is one of the most important zoonotic pathogens that can cause both acute and chronic illnesses in poultry flocks, and can also be transmitted to humans from infected poultry. The purpose of this study was to investigate the prevalence, antimicrobial resistance, and molecular characteristics of Salmonella isolated from diseased and clinically healthy chickens in Anhui, China. In total, 108 Salmonella isolates (5.66%) were successfully recovered from chicken samples (n = 1908), including pathological tissue (57/408, 13.97%) and cloacal swabs (51/1500, 3.40%), and S. Enteritidis (43.52%), S. Typhimurium (23.15%), and S. Pullorum (10.19%) were the three most prevalent isolates. Salmonella isolates showed high rates of resistance to penicillin (61.11%), tetracyclines (47.22% to tetracycline and 45.37% to doxycycline), and sulfonamides (48.89%), and all isolates were susceptible to imipenem and polymyxin B. In total, 43.52% isolates were multidrug-resistant and had complex antimicrobial resistance patterns. The majority of isolates harbored cat1 (77.78%), blaTEM (61.11%), and blaCMY-2 (63.89%) genes, and the antimicrobial resistance genes in the isolates were significantly positively correlated with their corresponding resistance phenotype. Salmonella isolates carry high rates of virulence genes, with some of these reaching 100% (invA, mgtC, and stn). Fifty-seven isolates (52.78%) were biofilm-producing. The 108 isolates were classified into 12 sequence types (STs), whereby ST11 (43.51%) was the most prevalent, followed by ST19 (20.37%) and ST92 (13.89%). In conclusion, Salmonella infection in chicken flocks is still serious in Anhui Province, and not only causes disease in chickens but might also pose a threat to public health security.

Emergence of OXA-484-Producing Klebsiella variicola in China

Purpose

The frequent and inappropriate use of antibiotics has caused a dramatic rise in the number, species, and degree of multi-drug resistant bacteria, making them more prevalent and difficult to treat. In this context, the aim of the present study was to characterize the OXA-484-producing strains isolated from a perianal swab of a patient by using whole-genome analysis.

Patients and Methods

In this study, carbapenemase-producing Klebsiella variicola was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), average nucleotide identity (ANI) and PCR. S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern blotting were utilized to characterize the plasmid profiles of K. variicola 4717. In particular, WGS was performed to obtain genomic information on this clinical isolate, and assemble all the plasmids of the bla _OXA-484-harboring strain.

Results

The antimicrobial susceptibility pattern of K. variicola 4717 revealed that it was resistant to a range of antibiotics, including aztreonam, imipenem, meropenem, ceftriaxone, cefotaxime, ceftazidime, levofloxacin, ciprofloxacin, piperacillin-tazobactam, methylene-sulfamer oxazole, amoxicillin-clavulanic acid, cefepime, and tigecycline. Its susceptibility to chloromycin was intermediate, while it was still susceptible to amikacin, gentamicin, fosfomycin, and polymyxin B. The presence of two companion plasmids, p4717_1 and p4717_2, together with a plasmid carrying the bla _OXA-484 gene was observed. An in-depth investigation of p4717-OXA-484 uncovered that it is an IncX3-type plasmid and shares a similar segment encoded by IS26. Given the similar genetic background, it was conceivable that bla _OXA-484 could have developed from bla _OXA-181 through a series of mutations.

Conclusion

Herein, we described the first genome sequence of K. variicola strain harbouring the class D β-actamase bla _OXA-484 in an Inc-X3-type plasmid. Our work also uncovered the genetic characterization of K. variicola 4717 and the importance of initiating antimicrobial detection promptly.

Tofu Whey Wastewater as a Beneficial Supplement to Poultry Farming: Improving Production Performance and Protecting against Salmonella Infection

Tofu whey wastewater (TWW) is a by-product of the tofu production process, and contains high amounts of organic products and Lactobacillus ap. However, no studies have been reported on whether naturally fermented TWW can be used as a beneficial additive for poultry production. This study analyzed the main nutritional components and microbial flora of naturally fermented TWW from rural tofu processing plants and their effect on chick production performance, role in modulating the biochemical and immune parameters, and protection against Salmonella enteritidis (S. enteritidis) infection. It was observed that the average pH of TWW was 4.08; therefore, the total viable count was 3.00 × 10⁹ CFU/mL and the abundance of Lactobacillus was 92.50%. Moreover, TWW supplementation increased the total weight gain and feed intake, reduced the feed/gain ratio, increased the length and relative weight of the gut, and reduced the colonization and excretion of S. enteritidis in chickens. Additionally, TWW decreased oxidative damage and pro-inflammatory cytokine secretion caused by S. enteritidis infection. In addition, TWW supplementation ensured the structure of the intestine remained relatively intact in S. enteritidis-infected chicken. Furthermore, TWW markedly promoted the intestinal barrier integrity and up-regulated the relative abundance of Lactobacillus, counteracting the changes in gut microbiota caused by S. enteritidis infection in chicken. In conclusion, our data demonstrated that TWW could be used as a beneficial addition to poultry production, providing a research basis for the further development of TWW as a health care application in in food-producing animal.