Background and aims:Carbapenem-resistant Enterobacterales (CRE) colonization is an important prerequisite to hospital-acquired infections (HAIs) caused by CRE and increased mortality. This study assessed the prevalence of, and risk factors for, CRE colonization among children admitted to a provincial pediatric hospital in a high-antimicrobial-resistance setting in Vietnam. Methods:A point prevalence survey was conducted on 15 August 2022 at a provincial pediatric hospital in the Red River Delta. Rectal swabs were collected from 376 hospitalized children after informed consent. Samples were inoculated on chromogenic selective agar for CRE detection, and bacterial identification and antimicrobial susceptibility testing were performed using the VITEK® 2 system. Clinical and demographic data were obtained from structured questionnaires and medical records. Logistic regression analyses were used to identify risk factors associated with CRE colonization. Results:CRE colonization was detected in 28.2% of hospitalized children. Colonization was more common among patients screened >48 hours after admission (30.8%) and hospitalization >48 hours was associated with a 2.27-fold increased risk of colonization (p = 0.026) compared with screening earlier. Prevalence increased with length of stay, reaching 40.8% among those hospitalized ≥7 days. Children ≤6 years had a colonization rate of 29.7%. The highest ward-level prevalence occurred in the Intensive Care Unit (77.8%), whereas the lowest rates were observed in trauma and nutrition wards (9.5%). Escherichia coli (40.6%), Klebsiella pneumoniae (34.4%), and Enterobacter cloacae (16.4%) were the predominant CRE species. Most isolates were resistant to 4-10 antimicrobial classes. CRE colonization was also significantly associated with sepsis at the time of assessment. Conclusions:CRE colonization was highly prevalent among pediatric inpatients in this provincial Vietnamese hospital, particularly among young children, those hospitalized for prolonged periods, and patients in intensive care or neonatal units. These findings underscore the urgent need to strengthen infection prevention and control (IPC) strategies and to implement targeted screening approaches to assess the effect on CRE transmission of improvement of IPC.

The intensification of commercial chicken production has increased antimicrobial use and manure generation, raising concerns about residues and resistant pathogens entering the environment. Use of raw chicken manure can introduce antimicrobial compounds and resistance determinants into agricultural soils. This study examined antimicrobial use and manure management practices among chicken farmers in Morogoro, Dar es Salaam, and Unguja, and identified key gaps in national regulatory frameworks and their on-farm implementation. A structured questionnaire was administered to 351 farmers to assess the types and usage of antimicrobials and manure handling practices. Farmers reported using fourteen antibiotic classes and four antiparasitic agents, with tetracycline being the most frequently used (54.1%). Most farmers in Unguja (97.7%), Dar es Salaam (87.3%), and Morogoro (70.9%) either apply manure as fertilizer, sell it, or both. A large proportion (93.2%) reported that they do not process manure before use or sale, mainly due to lack of technical knowledge (77.4%). Awareness of the health hazards posed by pathogens (43.3%) and drug residues (57.5%) is low. This study revealed critical gaps, including weak regulatory enforcement, inadequate surveillance systems, limited cross-sectoral integration, irrational antimicrobial use, and limited farmer awareness. Strengthening regulatory frameworks, improving farmer training, and promoting safer manure management methods are recommended to reduce the environmental dissemination of antimicrobial residues and resistance.

Vibrio vulnificus is one of the most lethal marine pathogens, causing wound infections, septicemia, and necrotizing soft tissue infection with case fatality rates exceeding 20%-50%. In Northern Europe, incidence is rising alongside warming coastal waters. The genomic relatedness between environmental and clinical isolates and the long-term persistence of virulent clades in temperate waters remains poorly defined. An analysis of 117 V. vulnificus genomes, including 60 newly sequenced (36 environmental isolates and 24 clinical isolates from Denmark, 1994-2023), 27 publicly available Nordic clinical genomes, and 30 comparative reference public genomes were analysed. Comparative genomics, virulence gene profiling, pangenome analysis, and core-genome SNP (Single Nucleotide Polymorphism) phylogeny were used to define clade structure, persistence, and genetic determinants of pathogenicity. Four major clades were identified; three (C2-C4) persisted for up to three decades and contained both clinical and environmental isolates. Clonal pairs (≤40 SNPs) linked environmental and clinical sources across up to 8 years and multiple countries. The virulence gene repertoire including the major virulence factors MARTX toxin genes (rtxA/B/C/D), chiRP (chitin-regulated pilus), flp2/tad2 pili (fimbrial low-molecular-weight protein/tight adherence pili), ilpA (immunogenic lipoprotein A), and ompU (outer membrane porin), and vvhA (V. vulnificus hemolysin).) were present in both environmental and clinical isolates. All isolates carried the tetracycline resistance gene tet(34). We report that environmental aquatic reservoirs harbor fully virulent V. vulnificus lineages, making human infections exposure-driven rather than the result of emerging novel lineages.

Lactococcus garvieae is an emerging pathogen in aquaculture, with increasing reports of outbreaks in tilapia farming across Asia. In this study, we investigated two disease outbreaks in tilapia (Oreochromis spp.) cage farms in Northern Vietnam in 2024. Affected fish exhibited clinical signs including exophthalmia, scale hemorrhages, and internal lesions such as hepatobiliary swelling and ascites, empty gut and intestinal hemorrhage. Bacterial isolates obtained from diseased fish were initially misidentified as Streptococcus agalactiae based on biochemical profiling, but were subsequently confirmed as L. garvieae using MALDI-TOF Mass Spectrometry and 16S rRNA sequencing. Whole-genome sequencing of eight isolates revealed remarkable genomic homogeneity, with all strains assigned to multilocus sequence type ST95 and showing <= 9 SNPs across the core genome. Comparative phylogenomic analysis placed the Vietnamese isolates within a clonal subclade together with ST95 genomes from fish and human sources in East Asia, indicating recent expansion and possible regional transmission. Antimicrobial resistance gene screening detected only the mdt(A) and lsaD, consistent with high resistance to erythromycin, tetracycline, and doxycycline observed phenotypically. No plasmid-associated resistance genes were identified. Our findings highlight the emergence of a clonal L. garvieae ST95 lineage in Vietnamese aquaculture, characterized by high phenotypic antimicrobial resistance, and high genomic clonality. All L. garvieae strains from tilapia carried the full complement of 53 known virulence genes, including capsule biosynthesis genes, hemolysins (hly1-3), and LPxTG-anchored adhesins, underscoring their high pathogenic potential and explaining the severity of the clinical manifestations. These results underscore the importance of routine genomic surveillance, and strengthened biosecurity to mitigate the risk of further spread of L. garvieae in farmed fish populations. Although L. garviae is susceptible to only some antimicrobials traditionally used in aquaculture, the development of vaccines is needed.

This study addresses the limited information on use of antimicrobials and other chemical use in commercial tilapia farms in Bangladesh. A retrospective cross-sectional survey was conducted in November 2022 in the Mymensingh district, a major tilapia production hub. Nearly half of the farms (46.6%) experienced fish mortality during the last production cycle, and 75.0% of farmers did not seek professional assistance during disease outbreaks. Among those who did, 68.0% relied on chemical or drug suppliers for guidance rather than veterinary experts. Biosecurity practices were inadequate, with 98.3% not implementing four basic monitored measures: disinfection of vehicles, footwear, hands, and equipment. Awareness of antimicrobial use (AMU) risks among respondents was low, with 56.0% unaware of its negative impacts and 88.8% unfamiliar with antimicrobial resistance (AMR). Antibiotic use was low, with only 15.5% of farms reporting antibiotic treatments, primarily oxytetracycline hydrochloride (23.8%), enrofloxacin (19.0%), and erythromycin-sulphadiazine-trimethoprim (19.0%). However, other chemicals with antimicrobial properties, such as disinfectants, were more commonly applied, reported by 39.7% of farms for disease management. The use of both antimicrobial and non-antimicrobial medicine varied significantly by location, being significantly less likely observed in Tarakanda (p < 0.05) and Fulbaria (p < 0.01), suggesting location-specific differences in disease management. The presence of clinical signs was significantly associated with increased use of both antimicrobials, non-antimicrobial medicine and use of overall aquamedicine (p < 0.001), while longer cultivation durations showed a weak association with reduced AMU. Imprudent use of antimicrobials and other chemicals may pose One Health risks, including disruption of pond microbial ecosystems, AMR development, chemical residues, and occupational hazards. In-depth qualitative studies are needed to further understand and optimize antimicrobial and other chemical use practices and determine how tilapia farmers may benefit from improved biosecurity, training, and veterinary access.

Hospital wastewater (HWW) is a significant environmental and public health threat, containing high levels of pollutants such as antibiotic-resistant bacteria (ARB), antibiotic-resistant genes (ARGs), antibiotics, disinfectants, and heavy metals. This threat is of particular concern in low- and middle-income countries (LMICs), where untreated effluents are often used for irrigating vegetables crops, leading to direct and indirect human exposure. Despite being a potential hotspot for the spread of antimicrobial resistance (AMR), existing HWW treatment systems in LMICs primarily target conventional pollutants and lack effective standards for monitoring the removal of ARB and ARGs. Consequently, untreated or inadequately treated HWW continues to disseminate ARB and ARGs, exacerbating the risk of AMR proliferation. Addressing this requires targeted interventions, including cost-effective treatment solutions, robust AMR monitoring protocols, and policy-driven strategies tailored to LMICs. This perspective calls for a paradigm shift in HWW management in LMIC, emphasizing the broader implementation of onsite treatment systems, which are currently rare. Key recommendations include developing affordable and contextually adaptable technologies for eliminating ARB and ARGs and enforcing local regulations for AMR monitoring and control in wastewater. Addressing these challenges is essential for protecting public health, preventing the environmental spread of resistance, and contributing to a global effort to preserve the efficacy of antibiotics. Recommendations include integrating scalable onsite technologies, leveraging local knowledge, and implementing comprehensive AMR-focused regulatory frameworks.

This study evaluates the performance of a computer vision system (CVS) for measuring pig carcass contamination using latent class modelling, a statistical approach that does not depend on a gold standard. Developed by the Danish Technological Institute, the CVS integrates output from various cameras to inspect pig carcasses for presence of faecal contamination. Data from a 16-day period involving 69,215 carcasses were analysed, comparing CVS results with those from official auxiliaries. Descriptive analyses identified four meat inspection findings that were statistically associated with an increased relative risk of positives from the CVS, particularly oil contamination (RR = 4.1, P < 0.001), which the CVS could not differentiate from faecal contamination. Agreement between the CVS and official auxiliary was assessed using Cohen's kappa and prevalence- and bias-adjusted kappa (PABAK), with Cohen's Kappa indicating minimal agreement (κ = 0.17) and PABAK indicating moderate agreement (κ = 0.79). Sensitivity and specificity were estimated using a latent class model fit within a Bayesian framework, without assuming that either the CVS or official auxiliaries were perfect tests. The latent class model showed that the CVS had a median sensitivity of 31.6 % (95 % CI: 27.6 %-39.1 %) and specificity of 97.9 % (95 % CI: 96.1-99.9 %), compared to 22 % (95 % CI: 17.6 %-28.9 %) sensitivity and 99 % (95 % CI: 98.2 %-100 %) specificity for the official auxiliaries. These findings underscore the CVS's strength in detecting true contaminations and official auxiliaries' ability to rule out non-contaminations. This study demonstrates the applicability of latent class modelling for evaluating CVS, offering a flexible and reliable framework that addresses the limitations of traditional gold standard methods. The findings support the use CVS technology alongside traditional inspections to enhance food safety, paving the way for future integration of CVS in meat inspection, pending legislative adjustments.

We report the genomic characteristics of the human pathogen Vibrio cidicii isolated from seawater and green algae in the Baltic Sea. Initially misidentified as Vibrio vulnificus through culture and MALDI-TOF, whole-genome sequencing (WGS) confirmed them as V. cidicii, highlighting the importance of WGS analysis in accurate classification of emerging pathogens.

In 2020, Denmark buried approximately four million culled, farmed mink in mass graves treated with slaked lime due to widespread SARS-CoV-2 infections. After six months, environmental concerns prompted the exhumation of these cadavers. Our analysis encompassed visual inspections, soil pH measurements, and gas emission assessments of the grave environment. Additionally, we evaluated carcasses for decay status, cadaverine content, and the presence of various pathogens, including SARS-CoV-2 and mink coronavirus. Our findings revealed minimal microbial activity and limited carcass decomposition. Although viral RNA from SARS-CoV-2 and mink coronavirus, along with DNA from Aleutian mink disease virus, were detected, the absence of infectious SARS-CoV-2 in cell culture assays suggests slow natural degradation processes. This study provides critical insights for future considerations in managing mass burial scenarios during outbreaks of livestock-associated zoonotic pathogens.

Salmonella enterica is a globally important zoonotic microorganism that affects pigs and can enter the farm through various routes. This study aimed to determine the prevalence of S. enterica in water sources and pigs at Colombian pig farms, and to characterize the antimicrobial resistance of the isolates phenotypically and genotypically. Samples were collected from 103 farms including source water (n = 104), storage tank water (n = 103), drinking water (n = 103), and individual rectal swab samples (n = 1025). The presence of Salmonella was detected/identified using MDS-3M™ agar culture medium. Isolates were serotyped, and their antibiotic susceptibility was determined by minimum inhibitory concentration (MIC). Whole genome sequencing (WGS) was performed using Illumina NovaSeq, and bioinformatics analysis focused on serovar confirmation, MLST determination, and resistance gene detection. The overall between-farm prevalence of Salmonella enterica including all types of samples was 52.4% (54/103), with 6.4% of rectal swab samples and 21.3% of water samples found to be positive. Thirty serovars were identified using WGS, with the most common being S. Typhimurium var. monophasic (1,4,[5],12:i:-) (41.2%), S. Schwarzengrund (4.2%), and S. Saintpaul (4.2%). Salmonella Typhimurium and its monophasic variant were more commonly found in rectal swabs than the remaining serotypes (relative risk = 2.9, p < 0.0001), which were commonly found in the water samples (relative risk = 5.2, p < 0.0001). High levels of phenotypic resistance were observed, particularly to amikacin (99.2%), tetracycline (59.7%), chloramphenicol (55.5%), and ampicillin (42%). All isolates carried genes conferring resistance to aminoglycosides (aac(6′)-Iaa), quinolones (qnrB19), and tetracyclines (tetA). In conclusion, S. enterica is prevalent in Colombian pig farms including the water supply, with the S. Typhimurium monophasic variant being predominant, and antimicrobial resistance is widespread.

AIMS:This study investigated occurrence of Salmonella in faecal sludge from public toilets in Nigeria and genetic relatedness of strains that have been reported to cause human infection across Africa. METHODS AND RESULTS:The study collected 150 human sludge from public toilets and identified Salmonella through culture and PCR. Isolates were tested for antimicrobial susceptibility and sequenced using Illumina MiSeq. Draft sequences were compared with sequence data from Enterobase and GenBank. Twenty-four (16.0%) of sewage samples were positive for Salmonella [CI95 (10.2-21.8)]. Salmonella serotype Give [sequence type (ST) 516], Salmonella serotype Seftenberg (ST-14), and Salmonella serotype Chester (ST-411) were the most prevalent serovars found in 45.8%, 16.7%, and 16.7% of samples, respectively. Most of the isolates were sensitive to the antimicrobials tested, only one isolate of Salmonella serotype Derby showed resistance to ampicillin and cefazolin. Notably, 91.7% of the strains had the aac (6)-Iaa gene and point mutations in parC, gyrA, and acrB. Salmonella serotype Chester showed genetic relatedness with strains from Benin Republic and South Africa. CONCLUSIONS:There is genetic relatedness of present strains and those associated with human infections in Africa.

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.

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.

Background Acinetobacter baumannii cause difficult-to-treat infections mostly among immunocompromised patients. Clinically relevant A. baumannii lineages and their carbapenem resistance mechanisms are sparsely described in Nigeria.Objective This study aimed to characterise the diversity and genetic mechanisms of carbapenem resistance among A. baumannii strains isolated from hospitals in southwestern Nigeria.Methods We sequenced the genomes of all A. baumannii isolates submitted to Nigeria’s antimicrobial resistance surveillance reference laboratory between 2016 – 2020 on an Illumina platform and performed in silico genomic characterisation. Selected strains were sequenced using the Oxford Nanopore technology to characterise the genetic context of carbapenem resistance genes.Results The 86 A. baumannii isolates were phylogenetically diverse and belonged to 35 distinct sequence types (STs), 16 of which were novel. 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. Majority (n=54) of the isolates were carbapenem-resistant, particularly the IC7 (100%) and IC9 (>91.7%) strains. bla OXA-23 (34.9%) and bla NDM-1 (27.9%) were the most common carbapenem resistance genes detected. All bla OXA-23 genes were carried on Tn 2006 or Tn 2006 -like transposons. Our findings suggest that the mobilisation of a 10kb Tn 125 composite transposon is the primary means of bla NDM-1 dissemination.Conclusion Our findings highlight an increase in bla NDM-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 are increasingly clinically relevant due to their propensity to harbour 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 characterised 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.

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.

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.

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.

Se realizó una revisión sistemática de literatura en las bases datos Science Direct, PubMed, SciELO, EBSCO host, Redalyc, ProQuest y Google Scholar, seguida de un metaanálisis para estimar la prevalencia combinada de Salmonella spp en canales de cerdos en plantas de beneficio del país. Se recopilaron 3007 artículos científicos, informes técnicos, trabajos de grado y presentaciones de reuniones técnicas publicados entre 2009 y 2020. Se retiraron aquellos que no cumplían con los criterios de inclusión. Se revisaron 51 estudios en detalle, seleccionando 11 documentos que se emplearon en el metaanálisis. La prevalencia combinada de Salmonella spp en canales de cerdo fue de 9.7% (4.0-16.2%). El metaanálisis mostró una alta heterogeneidad en las prevalencias. El bajo número de reportes relacionados con la prevalencia de Salmonella en plantas de beneficio porcino puso en evidencia la necesidad de estudiar, hacer seguimiento y reportar la presencia de Salmonella spp para mantener actualizado los datos de prevalencia del patógeno debido a su impacto en salud pública.

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.