Biotransformation of Sumatriptan by Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Salmonella enterica subsp. enterica.

This study aimed at the biotransformation of sumatriptan by Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Salmonella enterica subsp. enterica and the identification of the drug metabolites by liquid chromatography-mass spectrometry. The drug was incubated with the organisms in tryptic soya broth at 37 °C. The broth was filtered and subjected to liquid chromatography-mass spectrometry. The metabolites identified by the use of mass spectral (+ve ion mode) fragmentation patterns were (3-methylphenyl)methanethiol (Bacillus subtilis), 1-(4-amino-3-ethylphenyl)-N-methylmethanesulfonamide (Salmonella enterica subsp. enterica) and 1-{4-amino-3-[(1E)-3-(dimethylamino)prop-1-en-1-yl]phenyl}methanesulfinamide (Salmonella enterica subsp. enterica, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus). These metabolites exhibit high gastrointestinal absorption, no blood-brain barrier permeability (except (3-methylphenyl)methanethiol), a bioavailability score of 0.55 and no inhibitory effect on CYP2C19, CYP2C9, CYP2D6, CYP3A4 or cytochrome P450 1A2 (except (3-methylphenyl)methanethiol), as determined by SwissADME software ver. 2024. The metabolites appear to be more toxic than the parent drug, as suggested by their calculated median lethal dose values. All four organisms under investigation transformed sumatriptan to different chemical substances that were more toxic than the parent drug.

Polyphenolic extracts from Diospyros kaki and Vitis vinifera by-products stimulate cytoprotective effects in bacteria-cell host interactions by mediation of transcription factor Nrf2.

BACKGROUND: The intestinal and skin epithelium play a strong role against bacterial stimuli which leads to inflammation and oxidative stress when overwhelmed. Polyphenols from fruit-rich diets and by-products show promise against bacterial deleterious effects; however, their antibacterial and health-promoting effects remain understudied. PURPOSE: This study aimed to assess the impact of polyphenolic extracts of grape (GrPE), persimmon (PePE) and pomegranate (PoPE) by-products on bacterial pathogen-host interactions, focusing beyond growth inhibition to explore their effects on bacterial adhesion, invasion, and modulation of host responses. METHODS: The microdilution method, as well as the tetrazolium based MTT cell proliferation and cytotoxicity assay with crystal violet staining were used to identify extracts sub-inhibitory concentrations that interfere with bacterial adhesion, invasion or lipopolysaccharides (LPS) effect on cell hosts without compromising host viability. The cytoprotective effects of extracts were assessed in a knock-down model of nuclear factor erythroid 2-related factor 2 (Nrf2). RESULTS: All extracts demonstrated significant reductions in pathogen adhesion to Caco-2 and HaCaT cells while preserving cellular integrity. Notably, PePE exhibited specific efficacy against Salmonella enterica adhesion, attributed mostly to its gallic acid content, whereas PoPE reduced S. enterica invasion in Caco-2 cells. The extracts supported the prevalence of non-pathogenic and commensal strains of intestinal and skin surfaces, selectively reducing pathogenic adhesion. The extracts mitigated the oxidative stress, enhanced the barrier function, and modulated the pro-inflammatory cytokines in LPS-challenged cells. GrPE, rich in anthocyanins, and PePE were found to mediate their protective effects through Nrf2 activation, while PoPE exerted multifaceted actions independent of Nrf2. CONCLUSION: Our results highlight the therapeutic potential of GrPE, PePE, and PoPE in shaping bacterial-host interactions, endorsing their utility as novel nutraceuticals for both oral and topical applications to prevent potential bacterial infections through innovative mechanisms.

Ceftriaxone-resistant Salmonella enterica serovar Newport: a case report from South India.

Salmonella enterica serovar Newport is a human pathogen underreported in most developing countries. It is known for causing gastroenteritis and extraintestinal infections. In this case report, we report the case of ceftriaxone-resistant Salmonella enterica serovar Newport from South India, causing acute gastroenteritis in a sixty-year-old female patient having a history of antimicrobial therapy and recent hospital admission. Serovar Newport, especially among antibiotic-exposed patients, poses a significant public health threat due to its ability to acquire multidrug resistance. This emphasizes the necessity for robust surveillance and monitoring of nontyphoidal Salmonella infections, particularly given the limited data on serovar Newport in India. Vigilance in clinical practice and public health initiatives is crucial to effectively address the emergence and spread of multidrug-resistant strains.

Fabrication of smart nanogel based on carrageenan and green coffee extract as a long-term antifouling agent to improve biofilm prevention in food production.

This study investigates the extract of the bioactive compounds from green coffee extract (GCE) and the loading of two different concentrations of GCE (1% and 2%) onto carrageenan nanogels (CAR NGs) to compare their antibacterial and antibiofilm effects with unloaded nanogels (NGs). The bioactive compounds of GCE were characterized using GC-MS analysis. The GCE1 and GCE2 were successfully deposited onto the surface of CAR NGs. The antibacterial and antibiofilm potential of prepared NGs were conducted against some foodborne pathogens (E. coli O157, Salmonella enterica, Staphylococcus aureus, and Listeria monocytogenes). The results of GC-MS analysis indicated that there were identified 16 bioactive compounds in GCE, including caffeine (36.27%), Dodemorph (9.04%), and D-Glycero-d-ido-heptose (2.44%), contributing to its antimicrobial properties. The antibacterial coatings demonstrated a notable antimicrobial effect, showing zone of inhibition (ZOI) diameters of up to 37 mm for GCE2 loaded CAR NGs. The minimum inhibitory concentration (MIC) values for GCE2 loaded CAR NGs were 80 ppm for E. coli O157, and 120 ppm for S. enterica, S. aureus, and L. monocytogenes, achieving complete bacterial inactivation within 10-15 min of exposure. Both GCE1 and GCE2 loaded CAR NGs significantly reduced biofilm cell densities on stainless steel (SS) materials for E. coli O157, S. enterica, S. aureus, and L. monocytogenes, with reductions ranging from 60% to 95%. Specifically, biofilm densities were reduced by up to 95% for E. coli O157, 89% for S. enterica, 85% for S. aureus, and 80% for L. monocytogenes. Results of the toxicity evaluation indicated that the NGs were non-toxic and biocompatible, with predicted EC50 values proved their biocompatibility and safety. These results recommended that GCE loaded CAR NGs are promising as natural antimicrobial agents for enhancing food safety and extending shelf life. Further, the study concluded that incorporating GCE into CAR NGs is an effective strategy for developing sustainable antimicrobial coatings for the food industry and manufacturing.

Insights into the global genomic features of Salmonella enterica serovar Gallinarum biovars Gallinarum and Pullorum.

AIMS: Characterize global genomic features of 86 genomes of Salmonella Gallinarum (SG) and Pullorum (SP), which are important pathogens causing systemic infections in poultry. METHODS AND RESULTS: All genomes harbored efflux pump encoding gene mdsA and gold tolerance genes golS and golT. Aminoglycoside (aac(6')-Ib, aadA5, aph(6)-Id, aph(3'')-Ib, ant(2'')-Ia), beta-lactam (blaTEM-1, blaTEM-135), efflux pump (mdsB), fosfomycin (fosA3), sulfonamide (sul1, sul2), tetracycline [tet(A)], trimethoprim (dfrA17), acid (asr), and disinfectant (qacEdelta1) resistance genes, gyrA, gyrB, and parC quinolone resistance point mutations, and mercury tolerance genes (mer) were found in different frequencies. Additionally, 310 virulence genes, pathogenicity islands (including SPI-1, 2, 3, 4, 5, 6, 9, 10, 12, 13, and 14), plasmids [IncFII(S), ColpVC, IncX1, IncN, IncX2, and IncC], and prophages (Fels-2, ST104, 500465-1, pro483, Gifsy-2, 103 203_sal5, Fels-1, RE-2010, vB_SenS-Ent2, and L-413C) were detected. MLST showed biovar-specific sequence types, and core genome MLST showed country-specific and global-related clusters. CONCLUSION: SG and SP global strains carry many virulence factors and important antimicrobial resistance genes. The diverse plasmids and prophages suggest genetic variability. MLST and cgMLST differentiated biovars and showed profiles occurring locally or worldwide.

Colistin-, cefepime-, and levofloxacin-resistant Salmonella enterica serovars isolated from Egyptian chicken carcasses.

OBJECTIVES: The emergence of multidrug-resistant (MDR) Salmonella strains, especially resistant ones toward critically important antimicrobial classes such as fluoroquinolones and third- and fourth-generation cephalosporins, is a growing public health concern. The current study, therefore, aimed to determine the prevalence, and existence of virulence genes (invA, stn, and spvC genes), antimicrobial resistance profiles, and the presence of ß-lactamase resistance genes (blaOXA, blaCTX-M1, blaSHV, and blaTEM) in Salmonella strains isolated from native chicken carcasses in Egypt marketed in Mansoura, Egypt, as well as spotlight the risk of isolated MDR, colistin-, cefepime-, and levofloxacin-resistant Salmonella enterica serovars to public health. METHODS: One hundred fifty freshly dressed native chicken carcasses were collected from different poultry shops in Mansoura City, Egypt between July 2022 and November 2022. Salmonella isolation was performed using standard bacteriological techniques, including pre-enrichment in buffered peptone water (BPW), selective enrichment in Rappaport Vassiliadis broth (RVS), and cultivating on the surface of xylose-lysine-desoxycholate (XLD) agar. All suspected Salmonella colonies were subjected to biochemical tests, serological identification using slide agglutination test, and Polymerase Chain Reaction (PCR) targeting the invasion A gene (invA; Salmonella marker gene). Afterward, all molecularly verified isolates were screened for the presence of virulence genes (stn and spvC). The antimicrobial susceptibility testing for isolated Salmonella strains towards the 16 antimicrobial agents tested was analyzed by Kirby-Bauer disc diffusion method, except for colistin, in which the minimum inhibition concentration (MIC) was determined by broth microdilution technique. Furthermore, 82 cefotaxime-resistant Salmonella isolates were tested using multiplex PCR targeting the ß-lactamase resistance genes, including blaOXA, blaCTX-M1, blaSHV, and blaTEM genes. RESULTS: Salmonella enterica species were molecularly confirmed via the invA Salmonella marker gene in 18% (27/150) of the freshly dressed native chicken carcasses. Twelve Salmonella serotypes were identified among 129 confirmed Salmonella isolates with the most predominant serotypes were S. Kentucky, S. Enteritidis, S. Typhimurium, and S. Molade with an incidence of 19.4% (25/129), 17.1% (22/129), 17.1% (22/129), and 10.9% (14/129), respectively. All the identified Salmonella isolates (n = 129) were positive for both invA and stn genes, while only 31.8% (41/129) of isolates were positive for the spvC gene. One hundred twenty-one (93.8%) of the 129 Salmonella-verified isolates were resistant to at least three antibiotics. Interestingly, 3.9%, 14.7%, and 75.2% of isolates were categorized into pan-drug-resistant, extensively drug-resistant, and multidrug-resistant, respectively. The average MAR index for the 129 isolates tested was 0.505. Exactly, 82.2%, 82.2%, 63.6%, 51.9%, 50.4%, 48.8%, 11.6%, and 10.1% of isolated Salmonella strains were resistant to cefepime, colistin, cefotaxime, ceftazidime/clavulanic acid, levofloxacin, ciprofloxacin, azithromycin, and meropenem, respectively. Thirty-one out (37.8%) of the 82 cefotaxime-resistant Salmonella isolates were ß-lactamase producers with the blaTEM as the most predominant ß-lactamase resistance gene, followed by blaCTX-M1 and blaOXA genes, which were detected in 21, 16, and 14 isolates respectively). CONCLUSION: The high prevalence of MDR-, colistin-, cefepime-, and levofloxacin-resistant Salmonella serovars among Salmonella isolates from native chicken is alarming as these antimicrobials are critically important in treating severe salmonellosis cases and boost the urgent need for controlling antibiotic usage in veterinary and human medicine to protect public health.

Competitive exclusion products as an antimicrobial alternative to control Salmonella Heidelberg in broilers.

Intestinal infections caused by non-typhoidal Salmonella spp., along with antimicrobial resistance spread are a major food safety concern worldwide. Here, we evaluate the potential of competitive exclusion products developed by anaerobic or aerobic conditions to control systemic infection, cecal colonization, fecal excretion, and improve the intestinal health in broilers challenged by Salmonella Heidelberg (SH). A total of 105 day-old chickens were randomly distributed into three experimental groups: A (untreated control), B (treated with anaerobic culture), and C (treated with aerobic culture). During 21 days, morphometric parameters of the small intestine were analyzed using microscopy, fecal excretions by cloacal swabs, systemic infection, and cecal colonization by colony-forming unit counts (CFU/g). The results indicated the lowest number of positive swabs (45.33%) recovered from Group C, followed by Group B (71.8%) and Group A (85.33%). The bacterial enumeration revealed the lowest amounts in Group C at the necropsy realized in 5-, 7-, and 14-days post-infection (DPI) (P = 0.0010, P = 0.0048, and P = 0.0094, respectively). Statistical differences between intestinal morphometrics were observed in the Group C at 21 DPI. Our results suggest that the product developed under aerobic conditions can improve intestinal health, protecting birds against SH.

The effectiveness of endolysin ENDO-1252 from Salmonella bacteriophage-1252 against nontyphoidal Salmonella enterica.

Salmonella enterica (S. enterica) is the most common food and waterborne pathogen worldwide. The growing trend of antibiotic-resistant S. enterica poses severe healthcare threats. As an alternative antimicrobial agent, bacteriophage-encoded endolysins (endolysins) are a potential agent in controlling S. enterica infection. Endolysins are enzymes that particularly target the peptidoglycan layer of bacterial cells, leading to their rupture and destruction. However, the application of endolysins against Gram-negative bacteria is limited due to the presence of the outer membrane in the cell wall, which hinders the permeation of externally applied endolysins. This study aimed the prokaryotic expression system to produce the recombinant endolysin ENDO-1252, encoded by the Salmonella bacteriophage-1252 associated with S. Enteritidis. Subsequently, ENDO-1252 had strong lytic activity not only against S. Enteritidis but also against S. Typhimurium. In addition, ENDO-1252 showed optimal thermostability and lytic activity at 25°C with a pH of 7.0. In combination with 0.1 mM EDTA, the effect of 120 µg of ENDO-1252 for 6 hours exhibited the highest lytic activity, resulting in a reduction of 1.15 log or 92.87% on S. Enteritidis. These findings suggest that ENDO-1252 can be used as a potential and innovative antibacterial agent for controlling the growth of S. Enteritidis.

High prevalence and genomic features of multidrug-resistant Salmonella enterica isolated from chilled broiler chicken on retail sale in the United Arab Emirates.

Non-typhoidal Salmonella represents a significant global concern for food safety and One Health. Despite the United Arab Emirates (UAE) being a leading consumer of chicken meat globally, there is a lack of comprehensive understanding regarding the prevalence and genomic characteristics of Salmonella within the country. This study aims to address this gap by conducting a thorough analysis of Salmonella prevalence, antimicrobial resistance, and genomic profiles of isolates obtained from whole broiler carcasses retailed under chilled conditions in the UAE. Our findings reveal that Salmonella was detected in 41.2 % (130/315) of the sampled chilled broiler carcasses, with notable variability observed among samples sourced from six different companies. Phenotypic antimicrobial resistance (AMR) testing, among 105 isolates, highlighted high resistance rates to tetracycline (97.1 %), nalidixic acid (93.3 %), ampicillin (92.4 %), azithromycin (75.2 %), ciprofloxacin (63.8 %), and ceftriaxone (54.3 %). Furthermore, a concerning 99 % (104/105) of the isolates exhibited multidrug resistance. Whole-genome sequencing (WGS) of 60 isolates identified five serovars, with S. infantis/Sequence Type (ST) 32 (55 %) and S. Minnesota/ST-458 (28.3 %) being the most prevalent. WGS analysis unveiled 34 genes associated with antimicrobial resistance, including mcr-1.1 (only in two isolates), conferring resistance to colistin. The two major serovars, Infantis and Minnesota, exhibited significant variation (P-values <0.001) in the distribution of major AMR genes (aadA1, blaCMY-2, blaSHV-12, qnrB19, qnrS1, sul1, and sul2). Notably, the gene qacEdelta, conferring resistance to quaternary ammonium compounds commonly found in disinfectants, was universally present in all S. Infantis isolates (n = 33), compared to only one S. Minnesota isolate. Additionally, all S. Infantis isolates harbored the IncFIB (pN55391) plasmid replicon type. Major serovars exhibited distinct distributions of antimicrobial resistance genes, underscoring the importance of serovar-specific surveillance. These findings emphasize the critical need for continuous surveillance and intervention measures to address Salmonella contamination risks in poultry products, providing valuable insights for public health and regulatory strategies not only in the UAE but also globally.

An exploration of descriptive machine learning approaches for antimicrobial resistance: Multidrug resistance patterns in Salmonella enterica.

Salmonellosis is one of the most common foodborne diseases worldwide, with the ability to infect humans and animals. Antimicrobial resistance (AMR) and, particularly, multidrug resistance (MDR) among Salmonella enterica poses a risk to human health. Antimicrobial use (AMU) regulations in livestock have been implemented to reduce AMR and MDR in foodborne pathogens. In this study, we used an integrated machine learning approach to investigate Salmonella AMR and MDR patterns before and after the implementation of AMU restrictions in agriculture in the United States. For this purpose, Salmonella isolates from cattle in the National Antimicrobial Resistance Monitoring System (NARMS) dataset were analysed using three descriptive models consisting of hierarchical clustering, network analysis, and association rule mining. The analysis showed the impact of the United States' 2012 extra-label cephalosporin regulations on AMR trends and revealed a distinctive MDR pattern in the Dublin serotype. The results also indicated that each descriptive model provides insights on a specific aspect of resistance patterns and, therefore, combining these approaches make it possible to gain a deeper understanding of AMR.

In vitro conjugation of IncB/O-plasmid: Minimum inhibitory concentration of ß-lactams increases 16-fold in Salmonella enterica compared with Escherichia coli.

The use of antimicrobials in poultry leaves residues in the litter, favoring the emergence of antimicrobial-resistant pathogens and making it a source of contamination. An in vitro 4 × 4 factorial trial was performed to investigate the influence of four treatments, consisting of antimicrobial sub-concentrations, on the transference of IncB/O-plasmid through conjugation in four groups. Each group was composed of one plasmid donor bacterium (Escherichia coli H2332) and a recipient bacterium (Escherichia coli J62 or Salmonella enterica serovars, Enteritidis, Typhimurium, or Heidelberg). Our results showed a little decrease in the conjugation frequency in almost all treatments between the two bacterial species, which varied according to each strain. The MIC test revealed an increase of up to 4096-fold in resistance to beta-lactams in Salmonella serovars after plasmid acquisition. This finding suggests that some genetic apparatus may be involved in increased antimicrobial resistance in Salmonella serovars after the acquisition of primary resistance determinants.

Superhydrophobic coatings reduce human bacterial foodborne pathogen attachment to woods used in fresh produce harvest and postharvest packing.

Wood is reportedly more difficult to maintain in hygienic condition versus other food contact materials, yet its use in produce packing and retail warrants efforts to reduce the risk of microbial pathogen contamination and attachment. This study characterized antifouling capabilities of fluorinated silanes applied to wood used in fresh edible produce handling to render the wood superhydrophobic and less supportive of bacterial pathogen attachment. Pine and oak cubic coupon surfaces were treated with 1% (w/w) silane or left untreated. Treated and untreated coupons were inoculated with Salmonella enterica or Listeria monocytogenes and held to facilitate pathogen attachment for 1, 4, or 8 h. Silane treatment of wood produced significant reductions in the proportions of strongly attaching cells for both pathogens versus loosely attaching cells (P < 0.01). Salmonella attachment demonstrated a dependency on wood treatment; silane-treated wood supported a lower fraction of strongly adhering cells (1.87 ± 1.24 log CFU/cm2) versus untreated wood (3.72 ± 0.67 log CFU/cm2). L. monocytogenes demonstrated significant declines in strongly attaching cells during extended exposure to silane-treated wood, from 7.59 ± 0.14 to 5.27 ± 0.68 log CFU/cm2 over 8 h post-inoculation. Microscopic analysis demonstrated silane treatment increased the surface roughness of both woods, leading to superhydrophobic conditions on wood surfaces, consequently decreasing strong attachment of pathogenic bacteria.

Insertion with long target duplication in polymyxin B-induced resistant mutant of Salmonella.

OBJECTIVES: A Salmonella enterica subsp. diarizonae (hereafter S. diarizonae) clinical strain S499 demonstrated unique genomic features. The strain S499 was treated with polymyxin B in vitro to investigate the mechanism of resistance. METHODS: S499 was treated with polymyxin B by increasing concentration gradually to obtain a resistant mutant S499V. Whole genomes of the two strains were sequenced using Illumina HiSeq X-10 and PacBio RS II platforms. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to compare the gene expression. RESULTS: The chromosome of strain S499 contained a 40-kb DNA region that was replicated after treatment with polymyxin B and generated a triple tandem DNA repeat region in the chromosome of mutant strain S499V. This repeat region in S499V was flanked by IS1 and contained pmrD, pmrG, and arnBCADTEF operon. In comparison to the homologous 40-kb DNA region of strain S499, a few genes in the repeat DNA region of strain S499V contained truncating mutations that generate two open reading frames (ORFs). The expression of pmrD, pmrG, and arnT was significantly upregulated in S499V. CONCLUSION: The duplication and overexpression of pmrD, pmrG, and arnT operon may be responsible for the polymyxin B resistance of mutant strain S499V.

Emergence of Salmonella Infantis carrying the pESI-like plasmid from eggs in egg grading and packing plants in Korea.

The plasmid of emerging S. Infantis (pESI) or pESI-like plasmid in Salmonella enterica Infantis are consistently reported in poultry and humans worldwide. However, there has been limited research on these plasmids of S. Infantis isolated from eggs. Therefore, this study aimed to analyze the prevalence and characteristics of S. Infantis carrying the pESI-like plasmid from eggs in egg grading and packing plants. In this study, the pESI-like plasmid was only detected in 18 (78.3%) of 23 S. Infantis isolates, and it was absent in the other 9 Salmonella serovars. In particular, S. Infantis isolates carrying the pESI-like plasmid showed the significantly higher resistance to ß-lactams, phenicols, cephams, aminoglycosides, quinolones, sulfonamides, and tetracyclines than Salmonella isolates without the pESI-like plasmid (p < 0.05). Moreover, all S. Infantis isolates carrying the pESI-like plasmid were identified as extended-spectrum ß-lactamase (ESBL) producer, harboring the blaCTX-M-65 and blaTEM-1 genes, and carried non-ß-lactamase resistance genes (ant(3'')-Ia, aph(4)-Ia, aac(3)-IVa, aph(3')-Ic, sul1, tetA, dfrA14, and floR) against five antimicrobial classes. However, all isolates without the pESI-like plasmid only carried the blaTEM-1 gene among the ß-lactamase genes, and either had no non-ß-lactamase resistance genes or harbored non-ß-lactamase resistance genes against one or two antimicrobial classes. Furthermore, all S. Infantis isolates carrying the pESI-like plasmid carried class 1 and 2 integrons and the aadA1 gene cassette, but none of the other isolates without the pESI-like plasmid harbored integrons. In particular, D87Y substitution in the gyrA gene and IncP replicon type were observed in all the S. Infantis isolates carrying the pESI-like plasmid but not in the S. Infantis isolates without the pESI-like plasmid. The distribution of pulsotypes between pESI-positive and pESI-negative S. Infantis isolates was clearly distinguished, but all S. Infantis isolates were classified as sequence type 32, regardless of whether they carried the pESI-like plasmid. This study is the first to report the characteristics of S. Infantis carrying the pESI-like plasmid isolated from eggs and can provide valuable information for formulating strategies to control the spread of Salmonella in the egg industry worldwide.

Does Salmonella diarizonae 58:r:z53 Isolated from a Mallard Duck Pose a Threat to Human Health?

Salmonella diarizonae (IIIb) is frequently isolated from reptiles and less frequently from birds and mammals. However, its isolation from invasive human infections has not been widely reported. Migratory mallard ducks are excellent bioindicators of pathogen presence and pathogen antibiotic resistance (AMR). We present the first isolation from a mallard duck in central Europe of the antibiotic-resistant Salmonella enterica subsp. diarizonae with the unique antigenic pattern 58:r:z53 and report its whole-genome sequencing, serosequencing, and genotyping, which enabled the prediction of its pathogenicity and comparison with phenotypic AMR. The isolated strain was highly similar to S. diarizonae isolated from humans and food. Twenty-four AMR genes were detected, including those encoding aminoglycoside, fluoroquinolone, macrolide, carbapenem, tetracycline, cephalosporin, nitroimidazole, peptide antibiotic, and disinfecting agent/antiseptic resistance. Six Salmonella pathogenicity islands were found (SPI-1, SPI-2, SPI-3, SPI-5, SPI-9, and SPI-13). An iron transport system was detected in SPI-1 centisome C63PI. Plasmid profile analyses showed three to be present. Sequence mutations in the invA and invF genes were noted, which truncated and elongated the proteins, respectively. The strain also harbored genes encoding type-III secretion-system effector proteins and many virulence factors found in S. diarizonae associated with human infections. This study aims to elucidate the AMR and virulence genes in S. enterica subsp. diarizonae that may most seriously threaten human health.

Relative resistance of Salmonella serotypes (Typhimurium, Infantis, and Reading) to peroxyacetic acid on chicken wings.

Peroxyacetic acid (PAA) is widely used as an antimicrobial in poultry processing. Recent salmonellosis outbreaks caused by Salmonella Infantis (SI) from chicken products and Salmonella Reading (SR) from turkey products have raised concerns about their enhanced resistance (compared to Salmonella Typhimurium [ST]) to commonly used antimicrobial interventions such as PAA. The objective of this research was to evaluate the efficacy of PAA against Salmonella serotypes (Typhimurium, Infantis and Reading), effect on product color and decomposition of PAA at different pH levels. Fresh chicken wings (0.45 kg) were inoculated with a cocktail (ca. 6 log CFU/mL) of nalidixic acid resistant ST, rifampicin resistant SI and kanamycin resistant SR. Inoculated chicken wings were immersed in PAA solutions (100 or 500 ppm; adjusted to either pH 8.5 or unadjusted natural pH) for either 10 s or 60 min to replicate treatments for chicken parts or whole carcasses, respectively. Treated chicken wings were rinsed in buffered peptone water (100 mL) containing sodium thiosulfate (0.1 %), serially diluted in peptone water supplemented with 200 ppm of nalidixic acid, rifampicin or kanamycin for enumeration of ST, SI, and SR respectively, and plated on APC Petrifilm. Immersion of chicken wings in 500 ppm PAA for 60 min resulted in greater microbial reductions (P ≤ 0.05) of ST, SI, SR of ca. Two log CFU/mL each, compared to 10 s treatment. Regardless of concentration and pH of PAA, increased exposure time (60 min vs. 10 s) resulted in greater reductions (P ≤ 0.05) of ST, SI, SR. ST was slightly more resistant to PAA solutions than S. Infantis and S. Reading (P ≤ 0.05) for all experimental conditions (PAA conc, pH, and exposure times). Faster decomposition of PAA (100 and 500 ppm) was observed at pH 8.5 compared to unadjusted, natural pH (P ≤ 0.05). Product color (lightness, L*) was not affected regardless of the PAA concentration, exposure time or the pH.

Interference of gastrointestinal barriers with antibiotic susceptibility of foodborne pathogens: an in vitro case study of ciprofloxacin and tetracycline against Salmonella enterica and Listeria monocytogenes.

Minimum inhibitory concentrations (MIC) assays are often questioned for their representativeness. Especially when foodborne pathogens are tested, it is of crucial importance to also consider parameters of the human digestive system. Hence, the current study aimed to assess the inhibitory capacity of two antibiotics, ciprofloxacin and tetracycline, against Salmonella enterica and Listeria monocytogenes, under representative environmental conditions. More specifically, aspects of the harsh environment of the human gastrointestinal tract (GIT) were gradually added to the experimental conditions starting from simple aerobic lab conditions into an in vitro simulation of the GIT. In this way, the effects of parameters including the anoxic environment, physicochemical conditions of the GIT (low gastric pH, digestive enzymes, bile acids) and the gut microbiota were evaluated. The latter was simulated by including a representative consortium of selected gut bacteria species. In this study, the MIC of the two antibiotics against the relevant foodborne pathogens were established, under the previously mentioned environmental conditions. The results of S. enterica highlighted the importance of the anaerobic environment when conducting such studies, since the pathogen thrived under such conditions. Inclusion of physicochemical barriers led to exactly opposite results for S. enterica and L. monocytogenes since the former became more susceptible to ciprofloxacin while the latter showed lower susceptibility towards tetracycline. Finally, the inclusion of gut bacteria had a bactericidal effect against L. monocytogenes even in the absence of antibiotics, while gut bacteria protected S. enterica from the effect of ciprofloxacin.

Genomic investigation of Salmonella enterica Serovar Welikade from a pediatric diarrhea case first time in Shanghai, China.

BACKGROUND: Salmonella, an important foodborne pathogen, was estimated to be responsible for 95.1 million cases and 50,771 deaths worldwide. Sixteen serovars were responsible for approximately 80% of Salmonella infections in humans in China, and infections caused by a few uncommon serovars have been reported in recent years, though not with S. Welikade. This study reports the first clinical case caused by S. Welikade in China and places Chinese S. Welikade isolates in the context of global isolates via genomic analysis. For comparison, S. Welikade isolates were also screened in the Chinese Local Surveillance System for Salmonella (CLSSS). The minimum inhibitory concentrations (MICs) of 28 antimicrobial agents were determined using the broth microdilution method. The isolates were sequenced on an Illumina platform to identify antimicrobial resistance genes, virulence genes, and phylogenetic relationships. RESULTS: The S. Welikade isolate (Sal097) was isolated from a two-year-old boy with acute gastroenteritis in 2021. Along with the other two isolates found in CLSSS, the three Chinese isolates were susceptible to all the examined antimicrobial agents, and their sequence types (STs) were ST5123 (n = 2) and ST3774 (n = 1). Single nucleotide polymorphism (SNP)-based phylogenetic analysis revealed that global S. Welikade strains can be divided into four groups, and these three Chinese isolates were assigned to B (n = 2; Sal097 and XXB1016) and C (n = 1; XXB700). In Group B, the two Chinese ST5123 isolates were closely clustered with three UK ST5123 isolates. In Group C, the Chinese isolate was closely related to the other 12 ST3774 isolates. The number of virulence genes in the S. Welikade isolates ranged from 59 to 152. The galF gene was only present in Group A, the pipB2 gene was only absent from Group A, the avrA gene was only absent from Group B, and the allB, sseK1, sspH2, STM0287, and tlde1 were found only within Group C and D isolates. There were 15 loci unique to the Sal097 isolate. CONCLUSION: This study is the first to characterize and investigate clinical S. Welikade isolates in China. Responsible for a pediatric case of gastroenteritis in 2021, the clinical isolate harbored no antimicrobial resistance and belonged to phylogenetic Group B of global S. Welikade genomes.

Ultra violet-C pretreatment enhances the antimicrobial efficacy of unpeeled carrots against subsequent contamination with Listeria monocytogenes.

To our knowledge, this study is the first to elucidate the bactericidal efficacy of unpeeled carrots (hereafter referred to as carrots) pretreated with Ultra Violet-C (UV-C) against subsequent contamination with Listeria monocytogenes. Carrots pretreated with UV-C (240 mJ/cm2) exhibited a significant antilisterial effect within 2 h. In fact, the population of UV-C-pretreated carrots decreased from 7.94 log CFU/cm2 to levels below the limit of detection (LOD; <1.65 log CFU/cm2) within 24 h. For carrots that were not pretreated with UV-C, 3-4 log reductions were found after 24 h. Carrots pretreated with UV-C exhibited antimicrobial activity against another gram-positive pathogen, Staphylococcus aureus, but not against the gram-negative pathogens, E. coli O157:H7 and Salmonella enterica. Pretreatment with UV-C created a lasting antimicrobial effect as introducing L. monocytogenes on carrots, 72 h post-UV-C treatment, still maintained the antilisterial effect. Notably, all UV-C doses in the range of 48-240 mJ/cm2 induced a lasting antilisterial effect. The bactericidal effects against L. monocytogenes were confirmed in three varieties of washed and unwashed carrots (Danvers, Nantes, and Chantenay). Fluorescence microscopy confirmed the bactericidal effect of UV-C-pretreated carrots on the survival of L. monocytogenes. Conclusively, pretreating carrots with UV-C can reduce the population of L. monocytogenes to levels below the LOD and may further prevent pathogen growth during cold storage. Additional studies are necessary to discern the mechanism underlying the bactericidal efficacy of UV-C-pretreated carrots.

Antibacterial Properties of Peptide and Protein Fractions from Cornu aspersum Mucus.

The discovery and investigation of new natural compounds with antimicrobial activity are new potential strategies to reduce the spread of antimicrobial resistance. The presented study reveals, for the first time, the promising antibacterial potential of two fractions from Cornu aspersum mucus with an MW < 20 kDa and an MW > 20 kDa against five bacterial pathogens-Bacillus cereus 1085, Propionibacterium acnes 1897, Salmonella enterica 8691, Enterococcus faecalis 3915, and Enterococcus faecium 8754. Using de novo sequencing, 16 novel peptides with potential antibacterial activity were identified in a fraction with an MW < 20 kDa. Some bioactive compounds in a mucus fraction with an MW > 20 kDa were determined via a proteomic analysis on 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and bioinformatics. High homology with proteins and glycoproteins was found, with potential antibacterial activity in mucus proteins named aspernin, hemocyanins, H-lectins, and L-amino acid oxidase-like protein, as well as mucins (mucin-5AC, mucin-5B, mucin-2, and mucin-17). We hypothesize that the synergy between the bioactive components determined in the composition of the fraction > 20 kDa are responsible for the high antibacterial activity against the tested pathogens in concentrations between 32 and 128 µg/mL, which is comparable to vancomycin, but without cytotoxic effects on model eukaryotic cells of Saccharomyces cerevisiae. Additionally, a positive effect, by reducing the levels of intracellular oxidative damage and increasing antioxidant capacity, on S. cerevisiae cells was found for both mucus extract fractions of C. aspersum. These findings may serve as a basis for further studies to develop a new antibacterial agent preventing the development of antibiotic resistance.