Doxycycline pharmacokinetics and tissue depletion in striped catfish (Pagasianodon hypophthalmus) after oral administration.

The pharmacokinetics and residue depletion of doxycycline (DOX) in striped catfish (Pagasianodon hypophthalmus) after oral dosage were investigated. The pharmacokinetic experiment was conducted in an aquarium, while the experiment of residue depletion was performed in both an aquarium and earth ponds. Medicated feed was administered orally using the gavage method at a dosage of 20 mg/kg body weight. Blood, liver, and kidney from medicated fish samples were collected. In the depletion experiments, fish were fed medicated feed for five consecutive days at a dosage of 20 mg/kg body weight, with samples collected during and after medication. The concentrations of DOX were quantified using an LC-MS/MS system. The pharmacokinetics parameters of DOX in striped catfish included the absorption rate constant (ka), absorption half-life (T1/2abs), maximal plasma concentration (Cmax), time to maximal plasma concentration (Tmax), and area under the plasma concentration-time curve from time 0 to 96 h (AUC0-96 h) which were 0.12 h-1, 5.68 h, 1123.45 ng/mL, 8.19 h, and 25,018 ng/mL/h, respectively. Residue depletion results indicated that the withdrawal times of DOX in muscle (with skin) from fish kept in the aquarium were slightly longer than that in fish raised in earth ponds, corresponding to 194 degree-days compared with 150 degree-days. In conclusion, administration of DOX at the dosage of 20 mg/kg body weight can be used for treatment of bacterial infections in striped catfish, and a withdrawal time of 5 days at 29.4°C will ensure consumer food safety due to the rapid depletion of DOX from muscle and skin.

Genomic Insights into Edwardsiella ictaluri: Molecular Epidemiology and Antimicrobial Resistance in Striped Catfish (Pangasianodon hypophthalmus) Aquaculture in Vietnam.

Edwardsiella ictaluri is responsible for causing bacillary necrosis (BNP) in striped catfish (Pangasianodon hypophthalmus) in Vietnam. This study offers a comprehensive genomic characterization of E. ictaluri to enhance understanding of the molecular epidemiology, virulence, and antimicrobial resistance. E. ictaluri isolates were collected from diseased striped catfish in the Mekong Delta. The species was confirmed through PCR. Antimicrobial susceptibility testing was conducted using minimum inhibitory concentrations for commonly used antimicrobials. Thirty representative isolates were selected for whole genome sequencing to delineate their genomic profiles and phylogeny. All strains belonged to ST-26 and exhibited genetic relatedness, differing by a maximum of 90 single nucleotide polymorphisms. Most isolates carried multiple antimicrobial resistance genes, with the tet(A) gene present in 63% and floR in 77% of the genomes. The ESBL gene, blaCTX-M-15, was identified in 30% of the genomes. Three plasmid replicon types were identified: IncA, p0111, and IncQ1. The genomes clustered into two clades based on their virulence gene profile, one group with the T3SS genes and one without. The genetic similarity among Vietnamese isolates suggests that disease spread occurs within the Mekong region, underscoring the importance of source tracking, reservoir identification, and implementation of necessary biosecurity measures to mitigate spread of BNP.

Evaluation of screening algorithms to detect rectal colonization with carbapenemase-producing Enterobacterales in a resource-limited setting.

Objectives: To improve and rationalize the detection of carbapenemase-producing Enterobacterales (CPE) in rectal swabs in a high-prevalence and resource-constrained setting, addressing surveillance challenges typically encountered in laboratories with limited resources. Methods: A point prevalence survey (PPS) was conducted on 15 August 2022, in a provincial children's hospital in northern Vietnam. Rectal swab samples of all admitted children were collected and plated on a selective medium for carbapenem-resistant Enterobacterales (CRE). Species identification and antimicrobial susceptibility testing (AST) were performed by MALDI-TOF, and VITEK2 XL and interpreted according to CLSI breakpoints (2022). Carbapenemases were detected by the carbapenem inactivation method (CIM) and quantitative real-time PCR (qRT-PCR). Results: Rectal swab samples were obtained from 376 patients. Of 178 isolates growing on the CRE screening agar, 140 isolates were confirmed as Enterobacterales of which 118 (84.3%) isolates were resistant to meropenem and/or ertapenem. CIM and PCR showed that 90/118 (76.3%) were carbapenemase producers. Overall, 83/367 (22.6%) were colonized by CPE. Klebsiella pneumoniae, Escherichia coli and Enterobacter cloacae complex were the most common CPE detected, with NDM as the predominant carbapenemase (78/90; 86.7%). Phenotypic resistance to meropenem was the best predictor of CPE production (sensitivity 85.6%, specificity 100%) compared with ertapenem resistance (95.6% sensitivity, 36% specificity). CIM was 100% concordant with PCR in detecting carbapenemases. Conclusions: These findings underscore the effectiveness of meropenem resistance as a robust indicator of the production of carbapenemases and the reliability of the CIM method to detect such carbapenemases in resource-limited settings where the performance of molecular methods is not possible.

Nanopore sequencing for identification and characterization of antimicrobial-resistant Escherichia coli and Salmonella spp. from tilapia and shrimp sold at wet markets in Dhaka, Bangladesh.

Wet markets in low-and middle-income countries are often reported to have inadequate sanitation resulting in fecal contamination of sold produce. Consumption of contaminated wet market-sourced foods has been linked to individual illness and disease outbreaks. This pilot study, conducted in two major wet markets in Dhaka city, Bangladesh during a 4-month period in 2021 aimed to assess the occurrence and characteristics of Escherichia coli and non-typhoidal Salmonella spp. (NTS) from tilapia (Oreochromis niloticus) and shrimp (Penaeus monodon). Fifty-four individuals of each species were collected. The identity of the bacterial isolates was confirmed by PCR and their susceptibility toward 15 antimicrobials was tested by disk diffusion. The whole genome of 15 E. coli and nine Salmonella spp. were sequenced using Oxford Nanopore Technology. E. coli was present in 60-74% of tilapia muscle tissue and 41-44% of shrimp muscle tissue. Salmonella spp. was found in skin (29%) and gills (26%) of tilapia, and occasionally in muscle and intestinal samples of shrimp. The E. coli had several Multilocus sequence typing and serotypes and limited antimicrobial resistance (AMR) determinants, such as point mutations on glpT and pmrB. One E. coli (BD17) from tilapia carried resistance genes for beta-lactams, quinolones, and tetracycline. All the E. coli belonged to commensal phylogroups B1 and A and showed no Shiga-toxin and other virulence genes, confirming their commensal non-pathogenic status. Among the Salmonella isolates, five belonged to Kentucky serovar and had similar AMR genes and phenotypic resistance patterns. Three strains of this serovar were ST198, often associated with human disease, carried the same resistance genes, and were genetically related to strains from the region. The two undetermined sequence types of S. Kentucky were distantly related and positioned in a separate phylogenetic clade. Two Brunei serovar isolates, one Augustenborg isolate, and one Hartford isolate showed different resistance profiles. This study revealed high fecal contamination levels in tilapia and shrimp sold at two main wet markets in Dhaka. Together with the occurrence of Salmonella spp., including S. Kentucky ST198, a well-known human pathogen, these results stress the need to improve hygienic practices and sanitation standards at markets to improve food safety and protect consumer health.

NDM-1- and OXA-23-producing Acinetobacter baumannii in wastewater of a Nigerian hospital.

IMPORTANCE: Acinetobacter baumannii is a leading cause of hospital-associated infections globally. A. baumannii reservoirs outside hospital settings are still unknown, and their occurrence in the environment is linked to clinical and anthropogenic activities. Although the risk of transmission of A. baumannii from environmental sources to humans is not fully understood, these sources pose significant risks for the continued dissemination of A. baumannii and their resistance traits. This study provides evidence that diverse and clinically relevant A. baumannii strains, many of which are resistant to carbapenems, are constantly being discharged into the environment through inadequately treated hospital wastewater. We further elucidate potential transmission routes between the environment and clinical infections and demonstrate the high prevalence of carbapenem resistance genes on highly mobile transposons among these strains. Our findings highlight the pressing need to address hospital wastewater as a crucial factor in curtailing the spread of carbapenem-resistant A. baumannii.

Comparative genomic analysis of Aeromonas dhakensis and Aeromonas hydrophila from diseased striped catfish fingerlings cultured in Vietnam.

Introduction: Motile Aeromonas septicemia (MAS) is a burden for striped catfish (Pangasius hypophthalmus) farmers in Vietnam. MAS can be caused by several species of Aeromonas but Aeromonas hydrophila is seen as the leading cause of MAS in aquaculture, but recent reports suggest that A. dhakensis is also causing MAS. Methods: Here we investigated the bacterial etiology of MAS and compared the genomic features of A. hydrophila and A. dhakensis. We collected 86 isolates from diseased striped catfish fingerlings over 5 years from eight provinces in Vietnam. Species identification was done using PCR, MALDI-TOF and whole genome sequence (WGS). The MICs of commonly used antimicrobials was established. Thirty presumed A. hydrophila isolates were sequenced for species confirmation and genomic comparison. A phylogenetic analysis was conducted using publicly available sequences and sequences from this study. Results: A total of 25/30 isolates were A. dhakensis sequence type (ST) 656 and 5/30 isolates were A. hydrophila ST 251. Our isolates and all publicly available A. hydrophila isolates from Vietnam belonged to ST 251 and differed with <200 single nucleotide polymorphisms (SNP). Similarly, all A. dhakensis isolates from Vietnam belonged to ST 656 and differed with <100 SNPs. The tet(A) gene was found in 1/5 A. hydrophila and 19/25 A. dhakensis. All A. hydrophila had an MIC ≤2 mg/L while 19/25 A. dhakensis had MIC ≥8 mg/L for oxytetracycline. The floR gene was only found in A. dhakensis (14/25) which showed a MIC ≥8 mg/L for florfenicol. Key virulence genes, i.e., aerA/act, ahh1 and hlyA were present in all genomes, while ast was only present in A. dhakensis. Discussion: This study confirms previous findings where A. dhakensis was the dominating pathogen causing MAS and that the importance of A. hydrophila has likely been overestimated. The differences in antimicrobial susceptibility between the two species could indicate a need for targeted antimicrobial treatment plans. The lipopolysaccharide regions and outer membrane proteins did not significantly differ in their immunogenic potentials, but it remains to be determined with in vivo experiments whether there is a difference in the efficacy of available vaccines against A. hydrophila and A. dhakensis.

Changes in fatty acids during storage of artisanal-processed freshwater sardines (Rastrineobola argentea).

For ages, indigenous small fish species have been important in food and nutritional security of poor communities in low income countries. Freshwater fish, in particular fatty fish species are attracting a great attention because they are good sources of health promoting long chain omega-3 fatty acids. Docosahexaenoic acid (DHA, C22:6n-3), Docosapentaenoic acid (DPA, C22:5n-3) and eicosapentaenoic acid (EPA, C20:5n-3) are the main omega-3 PUFAs known to confer health benefits in humans if consumed in required amounts. While nutritionally valued, omega-3 PUFAs in fish are susceptible to oxidative damage during processing, transportation and subsequent storage. Lake Victoria sardines (Rastrineobola argentea), are rich source of chemically unstable omega-3 fatty acids DHA, DPA and EPA. Traditionally, sardines are preserved by sun drying, deep frying and smoking. Sardine products are transported, stored and marketed at ambient temperatures. Generally, uncontrolled and higher temperatures are known to increase vulnerability of polyunsaturated fatty acids to oxidation which in turn results into loss of nutritional and sensory qualities. This study investigated changes of fat acids in sun dried, deep fried and smoked sardines during storage. Lipolysis and the progressive hydroperoxides formation were monitored by free fatty acids (FFAs) and peroxide value (PV) respectively. None volatile secondary products of lipid oxidation were measured by thiobabituric acid reactive substances (TBARS). Fatty acids were analyzed by gas chromatography with a flameionization detector (GC-FID). Deep fried sardines maintained the lowest and apparently stable PV, TBARS and FFAs. Proportions of saturated fatty acids and polyunsaturated fatty acids decreased with time while that of monounsaturated fatty acids increased. Omega-3 fatty acids EPA, DPA and DHA decreased with increase in storage time. In 21 days of storage, DHA was oxidized beyond detectable levels in all sardine products. Gradual increase in FFAs in sun dried sardines was suggestive of lipid hydrolysis induced by enzymes.

Genomic traits of Aeromonas veronii isolated from slaughtered Danish broilers.

Aeromonas veronii is a Gram-negative opportunistic bacterium found in fish, poultry and humans and has occasionally been associated with disease although not generally considered a poultry pathogen. A. veronii was recently isolated from both healthy and condemned broiler carcasses at a major Danish abattoir. In this study, we did a whole genomic analysis of 24A. veronii strains from the abattoir to determine their potential sources and relatedness as well as their pathogenic potential, antimicrobial resistance determinants and associated mobile elements. No strains were multi-drug resistant, but all strains carried the beta-lactam resistance genes cphA3 and blaOXA-12 without being phenotypically resistant to carbapenems. One strain carried an IncA plasmid with tet(A), tet(B) and tet(E) genes. A phylogenetic tree including public A. veronii sequences showed that our isolates were not clonal but were dispersed around the phylogenetic tree, suggesting a diffuse spread of A. veronii across human, aquatic and poultry samples. Strains carried different virulence factors known to be associated with pathogenesis and severity of disease in animals and humans, e.g. type II (aerolysin, amylases, proteases, and cytotoxic enterotoxin Act) and III secretion systems where the latter has been associated with mortality in hospitalized patients. Although our genomic analysis of A. veronii shows zoonotic potential, epidemiological studies of human gastro-enteritis cases of A. veronii associated with consumption of broiler meat are needed. It remains to be proven if A. veronii is a true poultry pathogen and part of the established microflora in abattoirs and the gut-intestinal microflora of poultry.

High Genetic Diversity of Carbapenem-Resistant Acinetobacter baumannii Isolates Recovered in Nigerian Hospitals in 2016 to 2020.

Acinetobacter baumannii causes difficult-to-treat infections mostly among immunocompromised patients. Clinically relevant A. baumannii lineages and their carbapenem resistance mechanisms are sparsely described in Nigeria. This study aimed to characterize the diversity and genetic mechanisms of carbapenem resistance among A. baumannii strains isolated from hospitals in southwestern Nigeria. We sequenced the genomes of all A. baumannii isolates submitted to Nigeria's antimicrobial resistance surveillance reference laboratory between 2016 and 2020 on an Illumina platform and performed in silico genomic characterization. Selected strains were sequenced using the Oxford Nanopore technology to characterize the genetic context of carbapenem resistance genes. The 86 A. baumannii isolates were phylogenetically diverse and belonged to 35 distinct Oxford sequence types (oxfSTs), 16 of which were novel, and 28 Institut Pasteur STs (pasSTs). Thirty-eight (44.2%) isolates belonged to none of the known international clones (ICs). Over 50% of the isolates were phenotypically resistant to 10 of 12 tested antimicrobials. The majority (n = 54) of the isolates were carbapenem resistant, particularly the IC7 (pasST25; 100%) and IC9 (pasST85; >91.7%) strains. blaOXA-23 (34.9%) and blaNDM-1 (27.9%) were the most common carbapenem resistance genes detected. All blaOXA-23 genes were carried on Tn2006 or Tn2006-like transposons. Our findings suggest that a 10-kb Tn125 composite transposon is the primary means of blaNDM-1 dissemination. Our findings highlight an increase in blaNDM-1 prevalence and the widespread transposon-facilitated dissemination of carbapenemase genes in diverse A. baumannii lineages in southwestern Nigeria. We make the case for improving surveillance of these pathogens in Nigeria and other understudied settings. IMPORTANCE Acinetobacter baumannii bacteria are increasingly clinically relevant due to their propensity to harbor genes conferring resistance to multiple antimicrobials, as well as their ability to persist and disseminate in hospital environments and cause difficult-to-treat nosocomial infections. Little is known about the molecular epidemiology and antimicrobial resistance profiles of these organisms in Nigeria, largely due to limited capacity for their isolation, identification, and antimicrobial susceptibility testing. Our study characterized the diversity and antimicrobial resistance profiles of clinical A. baumannii in southwestern Nigeria using whole-genome sequencing. We also identified the key genetic elements facilitating the dissemination of carbapenem resistance genes within this species. This study provides key insights into the clinical burden and population dynamics of A. baumannii in hospitals in Nigeria and highlights the importance of routine whole-genome sequencing-based surveillance of this and other previously understudied pathogens in Nigeria and other similar settings.

Pilot study of the productivity and Salmonella seroprevalence in pigs administered organic acids.

Control of Salmonella in pig/pork production is important to protect public health because pork is one of the main sources of human infection. Moreover, antimicrobial use in pig farms should be kept low to minimize development and transmission of antimicrobial resistance. This pilot study evaluated the productivity and Salmonella seroprevalence in pigs administered organic acids (OA) compared to pigs given growth promoters in one farm in Antioquia, Colombia. Two groups each consisting of 60 pigs of 6-weeks of age were studied for 4 months. One group was provided feed and water with OA (Selko pH® and Selacid®), whereas the other group (control) received antimicrobial growth promoters according to routine feeding practices (tylosin and zinc bacitracin). Blood samples were taken three times (T1-T3) and pigs were weighted five times to calculate daily weight gain (DWG) and feed conversion ratio (FCR). Initially when the pigs were 6 weeks old (T1), the Salmonella seroprevalence was 1.7% in both groups. When the pigs were 11 weeks old (T2), the seroprevalence was significantly lower in pigs provided OA compared to the control group (19 vs. 47%, P < 0.001), whereas when the pigs were 23 weeks old (T3), the seroprevalence did not differ between the groups (62 vs. 77%; P = 0.075). The cumulative DWG was significantly higher in the intervention group than in the control group (713 vs. 667 g/day; P < 0.001). The cumulative FCR did not differ between groups (2.80 vs. 2.77; P = 0.144). The pilot study indicates that cleaning the water pipes and administrating OA improve productivity in pigs and delay exposure to Salmonella spp. when compared with growth promoters. Thus, OA could replace antimicrobial growth promoters and reduce antimicrobial use and resistance. However, the study should be repeated before firmer conclusions can be drawn.

Mitigating antimicrobial resistance (AMR) using implementation research: a development funder's approach.

Despite the escalating burden of antimicrobial resistance (AMR), the global response has not sufficiently matched the scale and scope of the issue, especially in low- and middle-income countries (LMICs). While many countries have adopted national action plans to combat AMR, their implementation has lagged due to resource constraints, dysfunctional multisectoral coordination mechanisms and, importantly, an under-recognized lack of technical capacity to adapt evidence-based AMR mitigation interventions to local contexts. AMR interventions should be tailored, context-specific, cost-effective and sustainable. The implementation and subsequent scale-up of these interventions require multidisciplinary intervention-implementation research (IIR). IIR involves both quantitative and qualitative approaches, occurs across a three-phase continuum (proof of concept, proof of implementation and informing scale-up), and across four context domains (inner setting, outer setting, stakeholders and the implementation process). We describe the theoretical underpinnings of implementation research (IR), its various components, and how to construct different IR strategies to facilitate sustainable uptake of AMR interventions. Additionally, we provide real-world examples of AMR strategies and interventions to demonstrate these principles in practice. IR provides a practical framework to implement evidence-based and sustainable AMR mitigation interventions.

Correlation of High Seawater Temperature with Vibrio and Shewanella Infections, Denmark, 2010-2018.

During 2010-2018 in Denmark, 638 patients had Vibrio infections diagnosed and 521 patients had Shewanella infections diagnosed. Most cases occurred in years with high seawater temperatures. The substantial increase in those infections, with some causing septicemia, calls for clinical awareness and mandatory notification policies.

Salmonella Heidelberg and Salmonella Minnesota in Brazilian broilers: Genomic characterization of third-generation cephalosporin and fluoroquinolone-resistant strains.

Salmonella serovars Heidelberg and Minnesota encoding antimicrobial resistance to third-generation cephalosporins and fluoroquinolones are often detected in poultry/poultry meat. We analysed the genomes of 10 Salmonella Heidelberg (SH) and 4 Salmonella Minnesota (SM) from faecal isolates of Brazilian poultry. These featured virulent and multidrug-resistant characteristics, with AmpC beta-lactamase (blaCMY-2 ) predominance (9/14), for all SM (4/4) and some SH (3/10) located on IncC plasmid replicons. IncC carrying blaCTX-M-2 was only detected among SH (3/10). Mutation in the gyrA/parC genes was present in all SH, whereas SM harboured parC mutation plus qnrB19 on ColRNAI plasmids (3/4). In silico resistance overall corroborated with phenotypic results. Core genome phylogenies showed close clustering and high similarities between the Brazilian and poultry meat/food isolates from Europe, and to human isolates from European countries with documented import of Brazilian poultry meat. Conjugation assays with SM successfully transferred blaCMY-2 , and qnrB19 to an Escherichia coli recipient. The findings reinforce the ongoing antimicrobial resistance acquisition of SH and Minnesota and the risks for disseminating resistant strains and/or mobile elements which may increasingly affect importing countries and the need for controlling AMR in major poultry-exporting countries like Brazil.

Prevalence and whole genome phylogenetic analysis reveal genetic relatedness between antibiotic resistance Salmonella in hatchlings and older chickens from farms in Nigeria.

The presence of Salmonella in hatchlings is the single most important risk factor for the introduction of Salmonella into poultry farms, and resistant strains are particularly worrisome, as they could affect treatment outcomes in humans infected through consumption of contaminated poultry products. This study estimated Salmonella prevalence, determined resistance profiles of strains recovered from hatchlings in Nigeria, and determined genetic relatedness between hatchling strains and strains from poultry farms. In this study, 300 fecal samples were collected. Salmonella was isolated by culture and confirmed by PCR, and isolates were tested for susceptibility to antimicrobials by the disk diffusion method. Strains were pair-end sequenced, and genomes were used to obtain serotypes and antibiotic resistance genes. Whole-genome based phylogenetic analysis was used to determine genetic relatedness between these isolates and strains from previously characterized older chicken within the same geographical area. A prevalence of 10.7% was obtained belonging to 13 Salmonella serovars. Resistance to kanamycin (30/32), ciprofloxacin (22/32), nalidixic acid (22/32), and sulfonamides (22/32) were the most commonly observed phenotypic resistances. Twenty-two (68.8%) isolates showed multidrug resistance. In silico predictions identified 36 antimicrobial resistance genes. Four (12.5%) and 22 (68.8%) strains showed point mutations in gyrA and parC. Commonly observed acquired resistance genes included sul1, sul2, sul3, and tet(A) as well as a variety of aminoglycoside-modifying genes. Eleven (34.4%) isolates were predicted to have genes that confer resistance to fosfomycin (fosA7, fosB). A strain of S. Stanleyville was predicted to have optrA, which confers resistance to furazolidone. Strains of S. Kentucky, S. Muenster, and S. Menston obtained from hatchlings showed close genetic relatedness by having less than 30 SNPs difference to strains recovered from chickens at farms previously receiving hatchlings from the same sources.

Genomic Microevolution of Vibrio cholerae O1, Lake Tanganyika Basin, Africa.

Africa's Lake Tanganyika basin is a cholera hotspot. During 2001-2020, Vibrio cholerae O1 isolates obtained from the Democratic Republic of the Congo side of the lake belonged to 2 of the 5 clades of the AFR10 sublineage. One clade became predominant after acquiring a parC mutation that decreased susceptibility to ciprofloxacin.

Salmonella Heidelberg and Salmonella Minnesota in Brazilian broilers: Genomic characterization of third-generation cephalosporin and fluoroquinolone-resistant strains

Salmonella serovars Heidelberg and Minnesota encoding antimicrobial resistance to third-generation cephalosporins and fluoroquinolones are often detected in poultry/poultry meat. We analysed the genomes of 10 Salmonella Heidelberg (SH) and 4 Salmonella Minnesota (SM) from faecal isolates of Brazilian poultry. These featured virulent and multidrug-resistant characteristics, with AmpC beta-lactamase (blaCMY-2 ) predominance (9/14), for all SM (4/4) and some SH (3/10) located on IncC plasmid replicons. IncC carrying blaCTX-M-2 was only detected among SH (3/10). Mutation in the gyrA/parC genes was present in all SH, whereas SM harboured parC mutation plus qnrB19 on ColRNAI plasmids (3/4). In silico resistance overall corroborated with phenotypic results. Core genome phylogenies showed close clustering and high similarities between the Brazilian and poultry meat/food isolates from Europe, and to human isolates from European countries with documented import of Brazilian poultry meat. Conjugation assays with SM successfully transferred blaCMY-2 , and qnrB19 to an Escherichia coli recipient. The findings reinforce the ongoing antimicrobial resistance acquisition of SH and Minnesota and the risks for disseminating resistant strains and/or mobile elements which may increasingly affect importing countries and the need for controlling AMR in major poultry-exporting countries like Brazil.

Characterization of Escherichia coli and other bacteria isolated from condemned broilers at a Danish abattoir.

Meat inspection is important to ensure food safety and protect public health. Visual inspection of slaughtered carcasses for pathological changes should be supported by bacteriological analysis to determine whether the entire carcass or parts of it should be condemned. The aim of this study was to determine the bacterial species present in different sample types from condemned broiler carcasses. Furthermore, we investigated the genetic characteristics, zoonotic potential, and relatedness of Escherichia coli, the predominant bacterial species isolated from the carcasses. A total of 400 broiler carcasses condemned because of cellulitis (100), scratches (100), hepatitis (100), and healthy control carcasses (100) were selected. Samples of meat, pathological lesion, and bone marrow of each carcass were obtained for microbial analysis. From the analyzed samples, 469 bacterial isolates were recovered with E. coli accounting for 45.8%, followed by Aeromonas spp. (27.9%), in particular A. veronii. The highest rate of bacterial isolation was observed in carcasses condemned with cellulitis, whereas carcasses with hepatitis had the lowest rate of bacterial isolation. Forty-four E. coli isolates originating from different sample types were selected for whole genome sequencing. A clonal relationship was shown between E. coli from different sample types of the same carcass condemned with cellulitis and scratches. A major clade of E. coli was found in carcasses condemned with cellulitis with isolates containing mdf(A), tet(A), and bla TEM-1B genes that confer resistance to macrolides, tetracycline, and ampicillin, respectively. E. coli in this clade all belonged to ST117 and clustered with E. coli isolates previously collected from dead chickens and carcasses condemned due to cellulitis in Denmark, Finland, and the United Kingdom. Bacterial evaluation results of carcasses condemned with cellulitis, scratches (moderate to severe skin lesion), and acute hepatitis confirmed the need for total condemnation of carcasses with these pathological findings. A similar evaluation should be done for carcasses affected with chronic hepatitis, and minor scratches lesions.

Characterisation of Salmonella Enteritidis ST11 and ST1925 Associated with Human Intestinal and Extra-Intestinal Infections in Singapore.

Salmonella Enteritidis is a major foodborne pathogen worldwide. In this study, a total of 276 S. enteritidis isolates, collected between 2016 and 2017 from human, food and farm/slaughterhouse samples, were studied to enhance the understanding of the epidemiology of human salmonellosis in Singapore. Results showed all 276 isolates belonged either to ST1925 (70.3%) or ST11 (29.7%), with ST11 being significantly more frequent in extra-intestinal isolates and chicken isolates. Food isolates, most of which were from poultry, showed the highest prevalence of resistance (33-37%) against beta-lactams or beta-lactams/beta-lactamase inhibitor combination (ampicillin, piperacillin and ampicillin/sulbactam). The analysis showed the detection of genes associated with resistance to aminoglycoside genes (99.6%), tetracycline (55.1%), and beta-lactams (14.9%) of all isolates. Nine types of plasmids were found in 266 isolates; the most common incompatibility group profiles were IncFIB(S)-IncFII(S)-IncX1 (72.2%) and IncFIB(S)-IncFII(S) (15.8%). Most plasmid harbouring isolates from chicken (63.6%, 14/22) and from human (73.8%, 175/237) shared the same plasmid profile (IncFIB(S)-IncFII(S)-IncX1). SNP analysis showed clustering of several isolates from poultry food products and human isolates, suggesting phylogenetic relatedness among these isolates. Lastly, this study provides important epidemiological insights on the application of phenotypic and next-generation sequencing (NGS) tools for improved food safety and public health surveillance and outbreak investigation of S.enteritidis.

Salmonella Salamae and S. Waycross isolated from Nile perch in Lake Victoria show limited human pathogenic potential.

Non-enterica subspecies of Salmonella enterica are rarely associated with human infections. Paradoxically, food safety legislations consider the entire genus Salmonella as pathogenic to humans. Globally, large amounts of seafoods are rejected and wasted due to findings of Salmonella. To inform better food safety decisions, we investigated the pathogenicity of Salmonella Salamae 42:r- and Salmonella Waycross isolated from Nile perch from Lake Victoria. Genome-wide analysis revealed absence of significant virulence determinants including on key Salmonella pathogenicity islands in both serovars. In epithelial cells, S. Salamae showed a weak invasion ability that was lower than the invH mutant of S. Typhimiurium used as negative control. Similarly, S. Salamae could not replicate inside macrophages. Moreover, intracellular replication in S. Waycross strains was significantly lower compared to the wild type S. Typhimurium. Our findings suggest a low pathogenicity of S. Salamae reinforcing the existing literature that non-enterica subspecies are avirulent. We propose that food legislations and actions taken on findings of Salmonella are revisited to avoid wasting valuable sea- and other foods.