Within-Host Diversity of Coagulase-Negative Staphylococci Resistome from Healthy Pigs and Pig Farmers, with the Detection of cfr-Carrying Strains and MDR-S. borealis

The ecology and diversity of resistome in coagulase-negative staphylococci (CoNS) from healthy pigs and pig farmers are rarely available as most studies focused on the livestock-associated methicillin-resistant S. aureus. This study aims to characterize the antimicrobial resistance (AMR) mechanisms, intra-host species diversity (more than one species in a host), and intra-species AMR diversity (same species with more than one AMR profile) in CoNS recovered from the nasal cavities of healthy pigs and pig farmers. One-hundred-and-one CoNS strains previously recovered from 40 pigs and 10 pig farmers from four Spanish pig farms were tested to determine their AMR profiles. Non-repetitive strains were selected (n = 75) and their AMR genes, SCCmec types, and genetic lineages were analyzed by PCR/sequencing. Of the non-repetitive strains, 92% showed a multidrug resistance (MDR) phenotype, and 52% were mecA-positive, which were associated with SCCmec types V (46.2%), IVb (20.5%), and IVc (5.1%). A total of 28% of the pigs and pig farmers had intra-host species diversity, while 26% had intra-species AMR diversity. High repertoires of AMR genes were detected, including unusual ones such as tetO, ermT, erm43, and cfr. Most important was the detection of cfr (in S. saprophyticus and S. epidermidis-ST16) in pigs and pig farmers; whereas MDR-S. borealis strains were identified in pig farmers. Pig-to-pig transmission of CoNS with similar AMR genes and SCCmec types was detected in 42.5% of pigs. The high level of multidrug, within-host, and intra-species resistome diversity in the nasal CoNS highlights their ability to be AMR gene reservoirs in healthy pigs and pig farmers. The detection of MDR-S. borealis and linezolid-resistant strains underscore the need for comprehensive and continuous surveillance of MDR-CoNS at the pig farm level

Pathogenicity and Antibiotic Resistance Diversity in Clostridium perfringens Isolates from Poultry Affected by Necrotic Enteritis in Canada

Necrotic enteritis (NE) caused by C. perfringens is one of the most common diseases of poultry and results in a huge economic loss to the poultry industry, with resistant clostridial strains being a serious concern and making the treatment difficult. Whole-genome sequencing approaches represent a good tool to determine resistance profiles and also shed light for a better understanding of the pathogen. The aim of this study was to characterize, at the genomic level, a collection of 20 C. perfringens isolates from poultry affected by NE, giving special emphasis to resistance mechanisms and production of bacteriocins. Antimicrobial resistance genes were found, with the tet genes (associated with tetracycline resistance) being the most prevalent. Interestingly, two isolates carried the erm(T) gene associated with erythromycin resistance, which has only been reported in other Gram-positive bacteria. Twelve of the isolates were toxinotyped as type A and seven as type G. Other virulence factors encoding hyaluronases and sialidases were frequently detected, as well as different plasmids. Sequence types (ST) revealed a high variability of the isolates, finding new allelic combinations. Among the isolates, C. perfringens MLG7307 showed unique characteristics; it presented a toxin combination that made it impossible to toxinotype, and, despite being identified as C. perfringens, it lacked the housekeeping gene colA. Genes encoding bacteriocin BCN5 were found in five isolates even though no antimicrobial activity could be detected in those isolates. The bcn5 gene of three of our isolates was similar to one previously reported, showing two polymorphisms. Concluding, this study provides insights into the genomic characteristics of C. perfringens and a better understanding of this avian pathogen

Searching for Antimicrobial-Producing Bacteria from Soils through an Educational Project and Their Evaluation as Potential Biocontrol Agents

Antimicrobial resistance (AMR) is a serious threat to public health due to the lack of effective drugs to combat infectious diseases, which generates the need to search for new antimicrobial substances. In this study, the potential of soil as a source of antimicrobial-producing bacteria (APB) was investigated and the importance of the connection between education and science was emphasized, using service-learning methodologies. Sixty-one soil samples were collected, and 1220 bacterial isolates were recovered. Eighteen of these isolates showed antimicrobial activity against at least 1 of the 12 indicator bacteria tested (including multidrug-resistant and relevant pathogens). The 18 APB were identified by MALDI-TOF and 6 different genera (Bacillus, Brevibacillus, Lysinobacillus, Peribacillus, Streptomyces, and Advenella) and 10 species were identified. The 18 APB were tested for antifungal activity against four phytopathogenic fungi (Botritis cynerea, Lecanicillium fungicola, Trichoderma harzianum, and Cladobotryum mycophilum). Moreover, the antibiotic susceptibility of APB was tested using the disk-diffusion method as well as their β-hemolytic activity (important safety criteria for potential future applications). A total of 10 of the 18 APB were able to inhibit at least 50% of indicator bacteria tested, including methicillin-resistant Staphylococcus aureus (MRSA), among others. A total of 4 of the 18 APB (3 Bacillus pumilus and 1 Bacillus altitudinis) showed inhibitory activity against two of the four fungal pathogens tested (B. cinerea and L. fungicola), as well as against 5–7 of the 12 bacterial pathogen indicators; these 4 isolates showed susceptibility to the antibiotics tested and lacked β-hemolytic activity and were considered promising APB for use as potential biocontrol agents. In addition, one Brevibacillus laterosporus strain had activity against 83% of indicator bacteria tested including Escherichia coli, MRSA and other methicillin-resistant staphylococci, as well as vancomycin-resistant enterococci (but not against fungi). These results show that soil is a source of APB with relevant antibacterial and antifungal activities, and also emphasize the importance of education and science to raise public awareness of the AMR problem and the strategies to control it

Comprehensive Approaches for the Search and Characterization of Staphylococcins

Novel and sustainable approaches are required to curb the increasing threat of antimicrobial resistance (AMR). Within the last decades, antimicrobial peptides, especially bacteriocins, have received increased attention and are being explored as suitable alternatives to antibiotics. Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria as a self-preservation method against competitors. Bacteriocins produced by Staphylococcus, also referred to as staphylococcins, have steadily shown great antimicrobial potential and are currently being considered promising candidates to mitigate the AMR menace. Moreover, several bacteriocin-producing Staphylococcus isolates of different species, especially coagulase-negative staphylococci (CoNS), have been described and are being targeted as a good alternative. This revision aims to help researchers in the search and characterization of staphylococcins, so we provide an up-to-date list of bacteriocin produced by Staphylococcus. Moreover, a universal nucleotide and amino acid-based phylogeny system of the well-characterized staphylococcins is proposed that could be of interest in the classification and search for these promising antimicrobials. Finally, we discuss the state of art of the staphylococcin applications and an overview of the emerging concerns

Comparative phylogenomics of extended-spectrum beta-lactamase-producing Escherichia coli revealed a wide diversity of clones and plasmids in Spanish chicken meat

International audienceAnimal food products are important sources of zoonotic agents, increasing the risk of exposure to antibioticresistant bacteria from farm to fork. Therefore, we aimed to detect and fully characterise Extended-Spectrum Beta-Lactamase (ESBL)-producing E. coli from the poultry sector in a One Health approach. From December 2021 to March 2022, 48 chicken meat samples were collected from 16 establishments in La Rioja (Northern Spain). Antibiotic susceptibility testing was assessed by the disk-diffusion method. Forty E. coli isolates were recovered from 33 of the 48 chicken meat samples tested (68.8%) when plated on MacConkey-agar. In addition, six ESBL-E. coli (6/48, 12.5%) were obtained on cefotaxime-supplemented MacConkey-agar, which were Whole-Genome Sequenced. A large diversity of clones and ESBL genes was observed, namely ST1140-E/bla CTX-M-32 (n = 1), ST752-A/bla TEM-52 (n = 1), ST117-B2/bla CTX-M-1 /bla SHV-12 (n = 2), ST10-A/bla SHV-12 (n = 1) and ST223-B1/ bla SHV-12 (n = 1). Three IncI1-plasmids (pST3-CC3) were found carrying the bla SHV-12 /bla CTX-M-1 /bla CTX-M-32 genes in two genetic environments: i) IS26-smc-glpR-bla SHV-12 -IS26; and ii) wbuC-bla CTX-M-32 /bla CTX-M-1 -ISEcp1. The bla TEM-52 gene was carried on a P1-like phage-plasmid flanked by an IS4-mediated composite transposon. An IncHI2 plasmid harboured a bla SHV-12 gene flanked by an IS26-mediated composite transposon but also additional genes conferring resistance to aminoglycosides, chloramphenicol, and sulphonamides. To analyse the cross-sectoral relatedness of our ESBL-E. coli isolates, our six genomes were mapped with publicly available genomes (n = 2588) related to the STs detected, revealing that one of our genomes (X3078-ST117) displayed strong similarities (34-40 allelic differences) with few genomes belonging to ST117 from the poultry sector from Germany and USA. This study demonstrated that the proportion of ESBL-E. coli is still high in chicken meat in Spain. In addition, the ST117 clone and the IncI1-bla CTX-M-1-32 /bla SHV-12 plasmids might represent successful clones and plasmids adapted to the chicken host

Detection and evaluation of the antimicrobial activity of Micrococcin P1 isolated from commensal and environmental staphylococcal isolates against MRSA

Bacteriocins (of different origins) have been proposed as promising alternatives to face antimicrobial resistance-associated health problems. Isolates of the Staphylococcus genus are well-known bacteriocin producers, especially coagulase-negative species.This study was funded by MCIN/AEI/10.13039/501100011033 (project PID2019-106158RB-I00) of Spain. A.P. acknowledges grants from Deutsche Forschungsgemeinschaft (DFG) TRR156 (project ID-246807620); TRR261 (project ID-398967434); and Cluster of Excellence EXC2124 Controlling Microbes to Fight Infection (CMFI) (project ID-390838134). R.F.-F. has a predoctoral contract (FPU18/05438) and a mobility fellowship (EST21/00631), Ministry of Spain.Peer reviewe