ABSTRACT
Comprehensive whole-genome sequencing was performed on two multi-drug-resistant Escherichia coli strains isolated from cattle manure from a typical dairy farm in Poland in 2020. The identified strains are resistant to beta-lactams, aminoglycosides, tetracyclines, trimethoprim/sulfamethoxazole, and fluoroquinolones. The complete sequences of the harbored plasmids revealed antibiotic-resistance genes located within many mobile genetic elements (e.g., insertional sequences or transposons) and genes facilitating conjugal transfer or promoting horizontal gene transfer. These plasmids are hitherto undescribed. Similar plasmids have been identified, but not in Poland. The identified plasmids carried resistance genes, including the tetracycline resistance gene tet(A), aph family aminoglycoside resistance genes aph(3â³)-lb and aph (6)-ld, beta-lactam resistance genes blaTEM-1 and blaCTX-M-15, sulfonamide resistance gene sul2, fluoroquinolone resistance gene qnrS1, and the trimethoprim resistance gene dfrA14. The characterized resistance plasmids were categorized into the IncY incompatibility group, indicating a high possibility for dissemination among the Enterobacteriaceae. While similar plasmids (99% identity) have been found in environmental and clinical samples, none have been identified in farm animals. These findings are significant within the One Health framework, as they underline the potential for antimicrobial-resistant E. coli from livestock and food sources to be transmitted to humans and vice versa. It highlights the need for careful monitoring and strategies to limit the spread of antibiotic resistance in the One Health approach. IMPORTANCE: This study reveals the identification of new strains of antibiotic-resistant Escherichia coli in cattle manure from a dairy farm in Poland, offering critical insights into the spread of drug resistance. Through whole-genome sequencing, researchers discovered novel plasmids within these bacteria, which carry genes resistant to multiple antibiotics. These findings are particularly alarming, as these plasmids can transfer between different bacterial species, potentially escalating the spread of antibiotic resistance. This research underscores the vital connection between the health of humans, animals, and the environment, emphasizing the concept of One Health. It points to the critical need for global vigilance and strategies to curb the proliferation of antibiotic resistance. By showcasing the presence of these strains and their advanced resistance mechanisms, the study calls for enhanced surveillance and preventive actions in both agricultural practices and healthcare settings to address the imminent challenge of antibiotic-resistant bacteria.
Subject(s)
Anti-Bacterial Agents , Drug Resistance, Multiple, Bacterial , Escherichia coli , Feces , Gene Transfer, Horizontal , Plasmids , Animals , Cattle , Plasmids/genetics , Escherichia coli/genetics , Escherichia coli/drug effects , Escherichia coli/isolation & purification , Drug Resistance, Multiple, Bacterial/genetics , Poland , Anti-Bacterial Agents/pharmacology , Feces/microbiology , Whole Genome Sequencing , Escherichia coli Infections/microbiology , Escherichia coli Infections/veterinary , Microbial Sensitivity TestsABSTRACT
The study describes the whole-genome sequencing of two antibiotic-resistant representative Escherichia coli strains, isolated from poultry manure in 2020. The samples were obtained from a commercial chicken meat production facility in Poland. The antibiotic resistance profile was characterized by co-resistance to ß-lactam antibiotics, aminoglycosides, and fluoroquinolones. The three identified resistance plasmids (R-plasmids), pECmdr13.2, pECmdr13.3, and pECmdr14.1, harbored various genes conferring resistance to tetracyclines (tetR[A]) for, aminoglycoside (aph, aac, and aad families), ß-lactam (blaCMY-2, blaTEM-176), sulfonamide (sul1, sul2), fluoroquinolone (qnrS1), and phenicol (floR). These plasmids, which have not been previously reported in Poland, were found to carry IS26 insertion elements, the intI1-integrase gene, and conjugal transfer genes, facilitating horizontal gene transfer. Plasmids pECmdr13.2 and pECmdr14.1 also possessed a mercury resistance gene operon related to transposon Tn6196; this promotes plasmid persistence even without antibiotic selection pressure due to co-selection mechanisms such as co-resistance. The chicken manure-derived plasmids belonged to the IncX1 (narrow host range) and IncC (broad host range) incompatibility groups. Similar plasmids have been identified in various environments, clinical isolates, and farm animals, including cattle, swine, and poultry. This study holds significant importance for the One Health approach, as it highlights the potential for antibiotic-resistant bacteria from livestock and food sources, particularly E. coli, to transfer through the food chain to humans and vice versa.
Subject(s)
Anti-Bacterial Agents , Drug Resistance, Multiple, Bacterial , Escherichia coli , Manure , Plasmids , Animals , Escherichia coli/genetics , Escherichia coli/drug effects , Poland , Drug Resistance, Multiple, Bacterial/genetics , Manure/microbiology , Anti-Bacterial Agents/pharmacology , Poultry , ChickensABSTRACT
When antimicrobial resistant bacteria (ARB) and genes (ARGs) reach novel habitats, they can become part of the habitat's microbiome in the long term if they are able to overcome the habitat's biotic resilience towards immigration. This process should become more difficult with increasing biodiversity, as exploitable niches in a given habitat are reduced for immigrants when more diverse competitors are present. Consequently, microbial diversity could provide a natural barrier towards antimicrobial resistance by reducing the persistence time of immigrating ARB and ARG. To test this hypothesis, a pan-European sampling campaign was performed for structured forest soil and dynamic riverbed environments of low anthropogenic impact. In soils, higher diversity, evenness and richness were significantly negatively correlated with relative abundance of >85% of ARGs. Furthermore, the number of detected ARGs per sample were inversely correlated with diversity. However, no such effects were present in the more dynamic riverbeds. Hence, microbiome diversity can serve as a barrier towards antimicrobial resistance dissemination in stationary, structured environments, where long-term, diversity-based resilience against immigration can evolve.
Subject(s)
Biodiversity , Drug Resistance, Bacterial , Microbiota , Soil Microbiology , Microbiota/genetics , Drug Resistance, Bacterial/genetics , Bacteria/genetics , Bacteria/classification , Bacteria/drug effects , Genes, Bacterial , Rivers/microbiology , Anti-Bacterial Agents/pharmacology , EcosystemABSTRACT
Manure from food-producing animals, rich in antibiotic-resistant bacteria and antibiotic resistance genes (ARGs), poses significant environmental and healthcare risks. Despite global efforts, most manure is not adequately processed before use on fields, escalating the spread of antimicrobial resistance. This study examined how different cattle manure treatments, including composting and storage, affect its microbiome and resistome. The changes occurring in the microbiome and resistome of the treated manure samples were compared with those of raw samples by high-throughput qPCR for ARGs tracking and sequencing of the V3-V4 variable region of the 16S rRNA gene to indicate bacterial community composition. We identified 203 ARGs and mobile genetic elements (MGEs) in raw manure. Post-treatment reduced these to 76 in composted and 51 in stored samples. Notably, beta-lactam, cross-resistance to macrolides, lincosamides and streptogramin B (MLSB), and vancomycin resistance genes decreased, while genes linked to MGEs, integrons, and sulfonamide resistance increased after composting. Overall, total resistance gene abundance significantly dropped with both treatments. During composting, the relative abundance of genes was lower midway than at the end. Moreover, higher biodiversity was observed in samples after composting than storage. Our current research shows that both composting and storage effectively reduce ARGs in cattle manure. However, it is challenging to determine which method is superior, as different groups of resistance genes react differently to each treatment, even though a notable overall reduction in ARGs is observed.
Subject(s)
Composting , Manure , Microbiota , Animals , Manure/microbiology , Cattle , Microbiota/drug effects , Poland , Farms , Drug Resistance, Microbial/genetics , RNA, Ribosomal, 16S , Dairying , Bacteria/genetics , Bacteria/drug effects , Anti-Bacterial Agents/pharmacologyABSTRACT
Due to the risk of pathogenic antibiotic-resistant bacteria and their antibiotic-resistance genes transfer from livestock feces to the soil and cultivated crops, it is imperative to find effective on-farm manure treatments to minimize that hazardous potential. An introduced worldwide policy of sustainable development, focus on ecological agricultural production, and the circular economy aimed at reducing the use of artificial fertilizers; therefore, such treatment methods should also maximize the fertilization value of animal manure. The two strategies for processing pig manure are proposed in this study-storage and composting. The present study examines the changes in the physicochemical properties of treated manure, in the microbiome, and in the resistome, compared to raw manure. This is the first such comprehensive analysis performed on the same batch of manure. Our results suggest that while none of the processes eliminates the environmental risk, composting results in a faster and more pronounced reduction of mobile genetic elements harboring antibiotic resistance genes, including those responsible for multi-drug resistance. Overall, the composting process can be an efficient strategy for mitigating the spread of antibiotic resistance in the environment and reducing the risk of its transfer to crops and the food chain while providing essential fertilizer ingredients.
Subject(s)
Manure , Soil Microbiology , Swine , Animals , Manure/microbiology , Drug Resistance, Microbial/genetics , Soil/chemistry , Genes, Bacterial , Crops, Agricultural/genetics , Anti-Bacterial Agents/pharmacology , Fertilizers/analysis , Livestock/geneticsABSTRACT
The dissemination of multidrug-resistant bacteria strains and genes carrying antibiotic resistance is currently considered to be one of the most important global problem. The WHO calls for the need to contain the spread of Antimicrobial Resistance (AMR) from all possible sources. There have been many international actions grouping scientists studying this phenomenon, and quite a lot of scientific projects devoted to this problem have already been carried out. As well, so far several strategies have been developed that can inhibit the AMR spread. In this mini-review, we highlight overlooked aspects that seem to be crucial for creating a comprehensive picture of AMR, especially in the context of One Health approach.
ABSTRACT
The application of chicken waste to farmland could be detrimental to public health. It may contribute to the dissemination of antibiotic-resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) from feces and their subsequent entry into the food chain. The present study analyzes the metagenome and resistome of chicken manure and litter obtained from a commercial chicken farm in Poland. ARB were isolated, identified, and screened for antibiogram fingerprints using standard microbiological and molecular methods. The physicochemical properties of the chicken waste were also determined. ARGs, integrons, and mobile genetic elements (MGE) in chicken waste were analyzed using high-throughput SmartChip qPCR. The results confirm the presence of many ARGs, probably located in MGE, which can be transferred to other bacteria. Potentially pathogenic or opportunistic microorganisms and phytopathogens were isolated. More than 50% of the isolated strains were classified as being multi-drug resistant, and the remainder were resistant to at least one antibiotic class; these pose a real risk of entering the groundwater and contaminating the surrounding environment. Our results indicate that while chicken manure can be sufficient sources of the nutrients essential for plant growth, its microbiological aspects make this material highly dangerous to the environment.
Subject(s)
Chickens , Microbiota , Angiotensin Receptor Antagonists , Angiotensin-Converting Enzyme Inhibitors , Animals , Anti-Bacterial Agents/pharmacology , Farms , Genes, Bacterial , Manure , Microbiota/geneticsABSTRACT
Listeria monocytogenes presents a dimorphism associated to the SecA2 activity with cells having a normal rod shape or a dysmorphic elongated filamentous form. Besides variation of the cell and colony morphotype, this cell differentiation has profound ecophysiological and physiopathological implications with collateral effects on virulence and pathogenicity, biotope colonisation, bacterial adhesion and biofilm formation. This suggests the SecA2-only protein export could influence the listerial cell surface, which was investigated first by characterising its properties in L. monocytogenes wt and ΔsecA2. The degree of hydrophilicity and Lewis acid-base properties appeared significantly affected upon SecA2 inactivation. As modification of electrostatic properties would owe to modification in the composition of cell-surface proteins, the proteosurfaceome was further investigated by shotgun label-free proteomic analysis with a comparative relative quantitative approach. Following secretomic analysis, the protein secretion routes of the identified proteins were mapped considering the cognate transport and post-translocational maturation systems, as well as protein categories and subcellular localisation. Differential protein abundance profiles coupled to network analysis revealed the SecA2 dependence of 48 proteins, including some related to cell envelope biogenesis, translation and protein export, which could account for modifications of adhesion and surface properties of L. monocytogenes upon SecA2 inactivation. This investigation unravelled the profound influence of SecA2 activity on the cell surface properties and proteosurfaceome of L. monocytogenes, which provides advanced insights about its ecophysiopathology. SIGNIFICANCE: L. monocytogenes is a foodborne zoonotic pathogen and etiological agent of human listeriosis. This species presents a cellular dimorphism associated to the SecA2 activity that has profound physiopathological and ecophysiological implications with collateral effects on bacterial virulence and colonisation. To explore the influence of the SecA2-only protein export on the listerial cell, the surface properties of L. monocytogenes expressing or depleted of SecA2 was characterised by microelectrophoresis, microbial affinity to solvents and contact angles analyses. As modifications of hydrophilicity and Lewis acid-base electrostatic properties would owe to modification in the composition of cell-surface proteins, the proteinaceous subset of the surfaceome, i.e. the proteosurfaceome, was investigated further by shotgun label-free proteomic analysis. This subproteome appeared quite impacted upon SecA2 inactivation with the identification of proteins accounting for modifications in the cell surface properties. The profound influence of SecA2 activity on the cell surface of L. monocytogenes was unravelled, which provides advanced insights about its ecophysiopathology.
Subject(s)
Listeria monocytogenes , Adenosine Triphosphatases , Bacterial Proteins/metabolism , Humans , Listeria monocytogenes/metabolism , Membrane Transport Proteins/physiology , ProteomicsABSTRACT
Antibiotic resistance genes (ARGs) are a relatively new type of pollutant. The rise in antibiotic resistance observed recently is closely correlated with the uncontrolled and widespread use of antibiotics in agriculture and the treatment of humans and animals. Resistant bacteria have been identified in soil, animal feces, animal housing (e.g., pens, barns, or pastures), the areas around farms, manure storage facilities, and the guts of farm animals. The selection pressure caused by the irrational use of antibiotics in animal production sectors not only promotes the survival of existing antibiotic-resistant bacteria but also the development of new resistant forms. One of the most critical hot-spots related to the development and dissemination of ARGs is livestock and poultry production. Manure is widely used as a fertilizer thanks to its rich nutrient and organic matter content. However, research indicates that its application may pose a severe threat to human and animal health by facilitating the dissemination of ARGs to arable soil and edible crops. This review examines the pathogens, potentially pathogenic microorganisms and ARGs which may be found in animal manure, and evaluates their effect on human health through their exposure to soil and plant resistomes. It takes a broader view than previous studies of this topic, discussing recent data on antibiotic use in farm animals and the effect of these practices on the composition of animal manure; it also examines how fertilization with animal manure may alter soil and crop microbiomes, and proposes the drivers of such changes and their consequences for human health.
ABSTRACT
Pseudomonas aeruginosa is a bacterium of high clinical and biotechnological importance thanks to its high adaptability to environmental conditions. The increasing incidence of antibiotic-resistant strains has created a need for alternative methods to increase the chance of recovery in infected patients. Various nanomaterials have the potential to be used for this purpose. Therefore, we aimed to study the physiological response of P. aeruginosa PAO1 to titanium dioxide/silica nanotubes. The results suggest that UV light-irradiated nanomaterial triggers strong agglomeration in the studied bacteria that was confirmed by microscopy, spectrophotometry, and flow cytometry. The effect was diminished when the nanomaterial was applied without initial irradiation, with UV light indicating that the creation of reactive oxygen species could play a role in this phenomenon. The nanocomposite also affected biofilm formation ability. Even though the biomass of biofilms was comparable, the viability of cells in biofilms was upregulated in 48-hour biofilms. Furthermore, from six selected genes, the mexA coding efflux pump was upregulated, which could be associated with an interaction with TiO2. The results show that titanium dioxide/silica nanotubes may alter the physiological and metabolic functions of P. aeruginosa PAO1.
Subject(s)
Nanocomposites/administration & dosage , Nanotubes/chemistry , Pseudomonas aeruginosa/drug effects , Silicon Dioxide/chemistry , Bacterial Outer Membrane Proteins/genetics , Biofilms/drug effects , Biofilms/growth & development , Drug Resistance, Multiple/drug effects , Drug Resistance, Multiple/genetics , Gene Expression Regulation, Bacterial/drug effects , Humans , Membrane Transport Proteins/genetics , Microbial Sensitivity Tests , Microscopy, Electron, Transmission , Nanocomposites/radiation effects , Nanocomposites/ultrastructure , Nanotubes/ultrastructure , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/genetics , Pseudomonas aeruginosa/physiology , Spectrometry, X-Ray Emission , Ultraviolet Rays , X-Ray DiffractionABSTRACT
As small, mobilizable replicons with a broad host range, IncQ plasmids are widely distributed among clinical and environmental bacteria. They carry antibiotic resistance genes, and it has been shown that they confer resistance to ß-lactams, fluoroquinolones, aminoglycosides, trimethoprim, sulphonamides, and tetracycline. The previously proposed classification system divides the plasmid group into four subgroups, i.e., IncQ-1, IncQ-2, IncQ-3, and IncQ-4. The last two subgroups have been poorly described so far. The aim of this study was to analyze five newly identified IncQ-3 plasmids isolated from a wastewater treatment plant in Poland and to compare them with all known plasmids belonging to the IncQ-3 subgroup whose sequences were retrieved from the NCBI database. The complete nucleotide sequences of the novel plasmids were annotated and bioinformatic analyses were performed, including identification of core genes and auxiliary genetic load. Furthermore, functional experiments testing plasmid mobility were carried out. Phylogenetic analysis based on three core genes (repA, mobA/repB, and mobC) revealed the presence of three main clusters of IncQ-3 replicons. Apart from having a highly conserved core, the analyzed IncQ-3 plasmids were vectors of antibiotic resistance genes, including (I) the qnrS2 gene that encodes fluoroquinolone resistance and (II) ß-lactam, trimethoprim, and aminoglycoside resistance genes within integron cassettes.
ABSTRACT
The cell wall (CW) of bacteria is an intricate arrangement of macromolecules, at least constituted of peptidoglycan (PG) but also of (lipo)teichoic acids, various polysaccharides, polyglutamate and/or proteins. During bacterial growth and division, there is a constant balance between CW degradation and biosynthesis. The CW is remodeled by bacterial hydrolases, whose activities are carefully regulated to maintain cell integrity or lead to bacterial death. Each cell wall hydrolase (CWH) has a specific role regarding the PG: (i) cell wall amidase (CWA) cleaves the amide bond between N-acetylmuramic acid and L-alanine residue at the N-terminal of the stem peptide, (ii) cell wall glycosidase (CWG) catalyses the hydrolysis of the glycosidic linkages, whereas (iii) cell wall peptidase (CWP) cleaves amide bonds between amino acids within the PG chain. After an exhaustive overview of all known conserved catalytic domains responsible for CWA, CWG, and CWP activities, this review stresses that the CWHs frequently display a modular architecture combining multiple and/or different catalytic domains, including some lytic transglycosylases as well as CW binding domains. From there, direct physiological and collateral roles of CWHs in bacterial cells are further discussed.
ABSTRACT
Distribution of amino acid substitutions in the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, parE and determinants of plasmid-mediated quinolone resistance (PMQR) were investigated among quinolone-resistant Salmonella spp. strains isolated from retail food in Poland in the years 2008-2013. Ten different amino acid substitutions were identified in QRDRs. Five different amino acid substitutions were identified in gyrA: Ser83Tyr, Ser83Phe, Asp87Tyr, Asp87Asn, Asp87Gly, two amino acid substitutions in parC: Thr57Ser, Ser80Ile and in parE: Leu445Phe, Arg511Ser. One substitution - Ser464Phe - was detected within gyrB. In gyrA a single substitution (Ser83Tyr) was identified the most frequently - 34.8% (63/181). Second most frequently identified variant (21.0%-38/181) was a co-existence of two single substitutions in gyrA: Ser83Tyr and parC: Thr57Ser. In four isolates co-existed three substitutions in three different genes: gyrA: Ser83Tyrâ¯+â¯parC: Thr57Serâ¯+â¯parE: Leu445Phe (two isolates), gyrA: Ser83Pheâ¯+â¯parC: Thr57Serâ¯+â¯parE: Leu445Phe, and gyrA: Ser83Tyrâ¯+â¯parC: Thr57Serâ¯+â¯parE: Arg511Ser. In the two isolates four substitutions were identified - in gyrA: Ser83Pheâ¯+â¯Asp87Tyr and in parC: Thr57Serâ¯+â¯Ser80Ile. Among resistant isolates, MIC values varied between 32 and 2048â¯mg/L (nalidixic acid) and between 0.125 and 16â¯mg/L (ciprofloxacin). MIC values of two isolates harboring qnrS1without any substitutions were 32â¯mg/L (NA) and 0.5-1.0â¯mg/L (CIP). The highest MIC values for NA and CIP were observed in two isolates of Salmonella spp. carrying double substitutions in gyrA: Ser83Pheâ¯+â¯Asp87Tyr and parC: Thr57Serâ¯+â¯Ser80Ile. MIC value for NA was 2048â¯mg/L while for CIP - 16â¯mg/L.
Subject(s)
Ciprofloxacin/pharmacology , Food Microbiology , Nalidixic Acid/pharmacology , Salmonella/drug effects , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial/genetics , Microbial Sensitivity Tests , Plasmids/genetics , Poland , Salmonella/geneticsABSTRACT
The chitinolytic system of Listeria monocytogenes thus far comprises two chitinases, ChiA and ChiB, and a lytic polysaccharide monooxygenase, Lmo2467. The role of the system in the bacterium appears to be pleiotropic, as besides mediating the hydrolysis of chitin, the second most ubiquitous carbohydrate in nature, the chitinases have been deemed important for the colonization of unicellular molds, as well as mammalian hosts. To identify additional components of the chitinolytic system, we screened a transposon mutant library for mutants exhibiting impaired chitin hydrolysis. The screening yielded a mutant with a transposon insertion in a locus corresponding to lmo0327 of the EGD-e strain. lmo0327 encodes a large (1,349 amino acids [aa]) cell wall-associated protein that has been proposed to possess murein hydrolase activity. The single inactivation of lmo0327, as well as of lmo0325 that codes for a putative transcriptional regulator functionally related to lmo0327, led to an almost complete abolishment of chitinolytic activity. The effect could be traced at the transcriptional level, as both chiA and chiB transcripts were dramatically decreased in the lmo0327 mutant. In accordance with that, we could barely detect ChiA and ChiB in the culture supernatants of the mutant strain. Our results provide new information regarding the function of the lmo0325-lmo0327 locus in L. monocytogenes and link it to the expression of chitinolytic activity.IMPORTANCE Many bacteria from terrestrial and marine environments express chitinase activities enabling them to utilize chitin as the sole source of carbon and nitrogen. Interestingly, several bacterial chitinases may also be involved in host pathogenesis. For example, in the important foodborne pathogen Listeria monocytogenes, the chitinases ChiA and ChiB and the lytic polysaccharide monooxygenase Lmo2467 are implicated in chitin assimilation but also act as virulence factors during the infection of mammalian hosts. Therefore, it is important to identify their regulators and induction cues to understand how the different roles of the chitinolytic system are controlled and mediated. Here, we provide evidence for the importance of lmo0327 and lmo0325, encoding a putative internalin/autolysin and a putative transcriptional activator, respectively, in the efficient expression of chitinase activity in L. monocytogenes and thereby provide new information regarding the function of the lmo0325-lmo0327 locus.
Subject(s)
Bacterial Proteins/metabolism , Chitinases/genetics , Gene Expression Regulation, Bacterial , Listeria monocytogenes/enzymology , Bacterial Proteins/genetics , Chitin/metabolism , Chitinases/metabolism , Gene Expression Regulation, Enzymologic , Listeria monocytogenes/genetics , Listeria monocytogenes/metabolism , Mutagenesis, InsertionalABSTRACT
Members of the genus Aeromonas that commonly occur in various aquatic ecosystems are taken into account as vectors spreading antibiotic resistance genes (ARGs) in the environment. In our study strains of Aeromonas spp. (n = 104) not susceptible to ampicillin were isolated from municipal sewage of different levels of purification - raw sewage, activated sludge and treated wastewater. The crucial step of the study was the identification of ß-lactamase resistance genes. The identified genes encode ß-lactamases from 14 families - blaTEM, blaOXA, blaSHV, blaCTX-M, blaMOX, blaACC, blaFOX, blaGES, blaPER, blaV EB, blaKPC, cphA, imiH, and cepH. There were no significant differences in number of identified ARGs between isolation points. BlaOXA, blaFOX variants and, characteristic for Aeromonas genus, metallo-ß-lactamase cphA-related genes were the most commonly identified types of ß-lactam resistance determinants. Moreover, we found four extended-spectrum ß-lactamases (blaSHV -11, blaCTX-M-27, blaCTX-M-98, and blaPER-4) - and seven AmpC (blaACC, blaFOX-2-like, blaFOX-3, blaFOX-4-like, blaFOX-9, blaFOX-10-like, and blaFOX-13-like) types and variants of genes that had never been found among Aeromonas spp. before. Five of the ß-lactamases families (blaTEM, blaOXA, blaFOX, blaV EB, and cphA) were identified in all three isolation sites, which supports the hypothesis that wastewater treatment plants (WWTPs) are hot spots of ARGs dissemination. The obtained ARGs sequences share high identity with previously described ß-lactamases, but new variants of those genes have to be considered as well. Characterization of antibiotic susceptibility was performed using disk the diffusion method with 12 different antibiotics according to CLSI guidelines. Over 60% of the strains are unsusceptible to cefepime and chloramphenicol and the majority of the strains have a multidrug resistance phenotype (68%). Finally, analysis of plasmid profiles among the resistant strains showed that 62% of the isolates from all three points of the WWTP carry plasmids of different sizes. Among some of the isolated plasmids blaFOX-4-like and blaGES genes have been found. To sum up, the results strongly suggest that Aeromonas spp. can be considered as agents of antibiotic resistance dissemination from wastewater to the natural environment.
ABSTRACT
The bacterial etiological agent of listeriosis, Listeria monocytogenes, is an opportunistic intracellular foodborne pathogen. The infection cycle of L. monocytogenes is well-characterized and involves several key virulence factors, including internalins A and B. While 35 genes encoding internalins have been identified in L. monocytogenes, less than half of them have been characterized as yet. Focusing on lmo2026, it was shown this gene encodes a class I internalin, InlL, exhibiting domains potentially involved in adhesion. Following a functional genetic approach, InlL was demonstrated to be involved in initial bacterial adhesion as well as sessile development in L. monocytogenes. In addition, InlL enables binding to mucin of type 2, i.e., the main secreted mucin making up the mucus layer, rather than to surface-located mucin of type 1. InlL thus appears as a new molecular determinant contributing to the colonization ability of L. monocytogenes.
ABSTRACT
This review summarizes current data on resistance among Salmonella spp. isolates of food origin from countries in different regions of the world. The mechanisms of resistance to different groups of antimicrobial compounds are also considered. Among strains resistant to quinolones and/or fluoroquinolones the most prevalent mechanism is amino acid substitutions in quinolone resistance-determining region (QRDR) of genes gyrA, parC but mechanism of growing importance is plasmid-mediated quinolone resistance (PMQR) associated with genes qnrA, qnrB, qnrC, qnrD, qnrS but frequency of their detection is different. Resistance to sulfonamides is mostly associated with genes sul1 and sul2, while resistance to trimethoprim is associated with various variants of dhfr ( dfr) genes. Taking into account Salmonella spp. strains isolated from food, resistance to ß-lactams is commonly associated with ß-lactamases encoding by blaTEM genes. However strains ESBL and AmpC positive are also detected. Resistance to aminoglicosides is commonly result of enzymatic inactivation. Three types of aminoglycoside modifying enzyme are: acetyltransferases (AAC), adenyltransferases (ANT) and phosphotransferases (APH). Resistance to tetracyclines among Salmonella spp. isolated from food is most commonly associated with active efflux. Among numerous genetic determinants encoding efflux pumps tetA, tetB, tetC, tetD, tetE and tetG are reported predominatingly. One of the most common mechanisms of resistance against chloramphenicol is its inactivation by chloramphenicol acetyltrasferases (CATs), but resistance to this compound can be also mediated by chloramphenicol efflux pumps encoded by the genes cmlA and floR. It is important to monitor resistance of Salmonella isolated from food, because the globalization of trade, leading to the long-distance
Subject(s)
Anti-Bacterial Agents/therapeutic use , Drug Resistance, Bacterial/drug effects , Foodborne Diseases/drug therapy , Foodborne Diseases/microbiology , Salmonella/drug effects , Salmonella/isolation & purification , Humans , Microbial Sensitivity TestsABSTRACT
INTRODUCTION AND OBJECTIVES: Antimicrobial resistance of pathogenic bacteria can result in therapy failure, increased hospitalization, and increased risk of death. In Poland, Salmonella spp. is a major bacterial agent of food poisoning. The majority of studies on antimicrobial resistance in Salmonella spp. isolates from food have focused on meat products as the source of this pathogen. In comparison, this study examines the antimicrobial susceptibility of Salmonella spp. isolated from retail food products other than meat in Poland. MATERIALS AND METHODS: A collection of 122 Salmonella spp. isolates were isolated in Poland in 2008-2012 from foods other than meat: confectionery products, eggs, fruits, vegetables, spices and others. The resistance of these isolates to 19 antimicrobial agents was tested using the disc diffusion method. RESULTS: Salmonella Enteritidis was the most frequently identified serotype (84.4% of all tested isolates). In total, 42.6% of the Salmonella spp. isolates were resistant to antibiotics. The highest frequencies of resistance were observed in isolates from 2009 (60.0%) and 2012 (59.5%). Antibiotic resistance was most prevalent among Salmonella spp. isolated from egg-containing food samples (68.0%). Resistance to nalidixic acid was most common and was observed in 35.2% of all tested isolates. The isolates were less frequently resistant to sulphonamides (6.6%), ampicillin (4.9%), amoxicillin/clavulanic acid (2.5%) and to streptomycin, cefoxitin, gentamicin and tetracycline (1.6%). Only one isolate showed resistance to chloramphenicol. Four isolates displayed multiresistance. CONCLUSIONS: Although, the level of resistance and multiresistance of Salmonella spp. isolates from non-meat foods was lower than in those from meat products, the presence of these resistant bacteria poses a real threat to the health of consumers.
Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Multiple, Bacterial , Food Microbiology , Salmonella/drug effects , Microbial Sensitivity Tests , Salmonella/isolation & purificationABSTRACT
The mobilome is a pool of genes located within mobile genetic elements (MGE), such as plasmids, IS elements, transposons, genomic/pathogenicity islands, and integron-associated gene cassettes. These genes are often referred to as "flexible" and may encode virulence factors, toxic compounds as well as resistance to antibiotics. The phenomenon of MGE transfer between bacteria, known as horizontal gene transfer (HGT), is well documented. The genes present on MGE are subject to continuous processes of evolution and environmental changes, largely induced or significantly accelerated by man. For bacteria, the only chance of survival in an environment contaminated with toxic chemicals, heavy metals and antibiotics is the acquisition of genes providing the ability to survive in such conditions. The process of acquiring and spreading antibiotic resistance genes (ARG) is of particular significance, as it is important for the health of humans and animals. Therefore, it is important to thoroughly study the mobilome of Aeromonas spp. that is widely distributed in various environments, causing many diseases in fishes and humans. This review discusses the recently published information on MGE prevalent in Aeromonas spp. with special emphasis on plasmids belonging to different incompatibility groups, i.e., IncA/C, IncU, IncQ, IncF, IncI, and ColE-type. The vast majority of plasmids carry a number of different transposons (Tn3, Tn21, Tn1213, Tn1721, Tn4401), the 1st, 2nd, or 3rd class of integrons, IS elements (e.g., IS26, ISPa12, ISPa13, ISKpn8, ISKpn6) and encode determinants such as antibiotic and mercury resistance genes, as well as virulence factors. Although the actual role of Aeromonas spp. as a human pathogen remains controversial, species of this genus may pose a serious risk to human health. This is due to the considerable potential of their mobilome, particularly in terms of antibiotic resistance and the possibility of the horizontal transfer of resistance genes.
ABSTRACT
Antimicrobial resistance of pathogenic bacteria, including Salmonella spp., is an emerging problem of food safety. Antimicrobial use can result in selection of resistant organisms. The food chain is considered a route of transmission of resistant pathogens to humans. In many European countries, sulfonamides are one of the most commonly used antimicrobials. The aim of our investigation was to assess the prevalence of sul genes and plasmid occurrence among sulfonamide-resistant Salmonella spp. Eighty-four sulfonamide-resistant isolates were collected in 2008 and 2013 from retail products in Poland. Minimal inhibitory concentration of all of these isolates was ≥1024 µg/mL. Resistant isolates were tested for the presence of sul1, sul2, sul3, and int1 genes by using multiplex polymerase chain reaction. In total, 44.0% (37/84) isolates carried the sul1 gene, 46.4% (39/84) were sul2 positive, while the sul3 gene was not detected in any of the sulfonamide-resistant isolates tested. It was found that 3.6% (3/84) of resistant Salmonella spp. contained sul1, sul2, and intI genes. All 33 intI-positive isolates carried the sul1 gene. Eleven of the sulfonamide-resistant isolates were negative for all the sul genes. Most of the sulfonamide-resistant Salmonella spp. harbored plasmids; only in eight isolates were no plasmids detected. Generally, the size of the plasmids ranged from approximately 2 kb to ≥90 kb. Our results revealed a relatively a high prevalence of sulfonamides-resistant Salmonella spp. isolated from retail food. Additionally, we have detected a high dissemination of plasmids and class 1 integrons that may enhance the spread of resistance genes in the food chain.