Abstract Background Klebsiella grimontii is a recently confirmed member of the Klebsiella oxytoca complex with significant clinical importance. As an opportunistic pathogen, reports of infections it causes are increasing, and the associated threats warrant attention. However, its phylogeny and epidemiological patterns remain poorly studied. Methods In this study, we identified a strain of Klebsiella grimontii, designated K767, simultaneously carrying the carbapenemase genes bla IMP-4 and bla KPC-2 through phenotypic assays and sequencing techniques from a tertiary hospital in Zhejiang Province, China. After performing whole-genome analysis of this strain, we integrated data from the NCBI public database, incorporating genomic information from a total of 235 Klebsiella grimontii strains for in-depth bioinformatics analysis. Results Genomic analysis revealed that in strain K767, bla IMP-4 is located on an IncHI5-type plasmid. This plasmid harbors multiple resistance modules and is highly conserved among similar plasmids originating from China. bla KPC-2 is located on an IncFII:IncFIA-type hybrid plasmid, a type predominantly found in Klebsiella species within China. Analysis of the 235 global strains indicated spatiotemporal heterogeneity in the distribution of sequenced isolates, with Europe contributing the most genomes. A total of 76 sequence types were identified, with Cluster III being the predominant evolutionary clade. The strains carried 75 acquired antimicrobial resistance genes, including various carbapenemase genes, and a significant co-occurrence was observed between certain resistance genes and specific plasmid replicons. Conclusion This study reports a strain of Klebsiella grimontii simultaneously carrying bla IMP-4 and bla KPC-2. These genes are carried by an IncHI5-type conjugative plasmid and an IncFII:IncFIA-type hybrid plasmid, respectively, both of which have been detected in sequenced isolates from China. Global population analysis suggests that this species exhibits high genetic diversity, with spatiotemporal heterogeneity in the distribution of sequenced isolates, and that plasmids may serve as potential vehicles for resistance genes. The findings provide an important basis for the clinical prevention and control of such resistant pathogens.
Biofilms are surface-associated microbial communities that dominate natural and host-associated environments and serve as major reservoirs for infections. Current therapeutics primarily target planktonic cells and are often ineffective against biofilms, highlighting the need for biofilm-specific strategies. Here, we investigated naturally occurring L-amino acids as antibiofilm agents against Candida albicans and Staphylococcus aureus. Administration of aspartic acid, cysteine, and glutamic acid reduced biofilm formation and established biofilm biomass in both single- and dual-species settings. Moreover, composite amino acid treatment enhanced fluconazole activity during C. albicans biofilm formation. These findings indicate that targeted amino acid administration, alone or in combination with existing antimicrobials, could provide a novel strategy for preventing and treating biofilm-associated infections.
Two diseases of economic and welfare impact in the dairy industry are mastitis and digital dermatitis (infectious lameness). To control and treat these two diseases under field conditions, antibiotics or toxic chemicals are first line treatments. In the current study, we evaluated novel biocides with potential for low environmental or human toxicity for their antimicrobial activity under field-like conditions. Fifteen biocides, including cuminaldehyde guanylhydrazone, and several other guanylhydrazone derivatives, were tested against two Treponema species, a Peptinophilus species, Streptococcus uberis, mastitis-associated E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, Mannheimia haemolytica, Fusobacterium necrophorum, and Porphyromonas levii. Bactericidal concentrations were determined by serial dilution of the biocide, incubation of log phase bacteria with the biocide for 10 min or longer and transfer to fresh growth media. Biocide compounds cuminaldehyde guanylhydrazone, related guanylhydrazone derivatives, thymol and ethyl lauroyl arginate were bactericidal in less than 10 min and effective in the presence of manure and milk. Additionally, these biocides demonstrate antibacterial activity in the presence of pre-formed biofilms. Given the broad range effectiveness of these biocides, further testing at larger scale and in vivo is needed to further develop these products as alternatives to traditional antibiotics or chemical treatments for use in livestock. Mastitis or mammary infections and lameness caused by digital dermatitis are two bacterial diseases that cause significant production losses and economic burden on producers. Antibiotics are used to treat mastitis in livestock, often without determining the bacterial cause or susceptibility of the bacteria to the antibiotic. Footbaths containing copper sulfate, zinc sulfate or formaldehyde are used to control digital dermatitis in dairies. These chemicals have environmental toxicity and human health concerns. As an alternative to antibiotics and harmful chemicals, we evaluated novel biocides that have potential for low human and environmental toxicity for their antibacterial activity. Of the biocides tested, cuminaldehyde guanylhydrazone, thymol and ethyl lauroyl arginate, performed as well or better than copper-containing compounds. These biocides were effective at low concentrations, had brief time to kill (10 minutes or less), and retained antibacterial activity in presence of manure and milk. Additionally, these compounds had the ability to kill bacteria present in a biofilm. Taken together, these novel biocides are promising compounds for further testing and eventual development into products for alternatives to traditional antibiotics for use in livestock.
Brachyspira hyodysenteriae is the classical etiological agent of swine dysentery (SD); however, strongly β-hemolytic species such as B. hampsonii and B. suanatina also cause SD-like disease and complicate surveillance and diagnosis. Fecal samples from two separate swine farms were submitted to the Iowa State University Veterinary Diagnostic Laboratory for SD surveillance. The resulting isolates were weakly β-hemolytic, and MALDI-TOF identified them as B. hyodysenteriae or other Brachyspira spp. but with low confidence scores (1.80–1.90). PCR assays for known species were also inconclusive. Therefore, we combined classical phenotypic characterization with genome-based analyses to establish the distinctiveness of this novel Brachyspira species. The two isolates shared an identical biochemical and enzymatic profile that differed clearly from B. hyodysenteriae and B. pilosicoli. Morphologically, they fell within the expected size and structural range of the genus, with 8–11 periplasmic flagella observed per cell. Average nucleotide identity analysis demonstrated only 76.5–91
The nasopharynx serves as a major reservoir for both commensal and pathogenic bacteria, with growing evidence linking its microbial composition to respiratory health and disease susceptibility. Here, we present the isolation and initial characterisation of a potentially novel Helcococcus taxon, provisionally named Helcococcus ekapensis. Isolates were cultured from archived nasopharyngeal samples collected as part of the Drakenstein Child Health study based in South Africa. Although Helcococcus species have previously been identified in the human respiratory tract, the genus remains poorly characterised within the human nasopharynx. We describe the isolation and culturing of three H. ekapensis isolates, SA-HE-C1, SA-HE-207, and SA-HE-338, and report its colony and cellular morphology. Our prevalence screening demonstrates that H. ekapensis colonisation of the infant nasopharynx increases with age over the first two years of life. Further, we report three draft genomes of these isolates, sharing close to 99
