Oral administration of recombinant outer membrane protein A-based nanovaccine affords protection against Aeromonas hydrophila in zebrafish.

Aeromonas hydrophila, an opportunistic warm water pathogen, has always been a threat to aquaculture, leading to substantial economic losses. Vaccination of the cultured fish would effectively prevent Aeromoniasis, and recent advancements in nanotechnology show promise for efficacious vaccines. Oral delivery would be the most practical and convenient method of vaccine delivery in a grow-out pond. This study studied the immunogenicity and protective efficacy of a nanoparticle-loaded outer membrane protein A from A. hydrophila in the zebrafish model. The protein was over-expressed, purified, and encapsulated using poly lactic-co-glycolic acid (PLGA) nanoparticles via the double emulsion method. The PLGA nanoparticles loaded with recombinant OmpA (rOmpA) exhibited a size of 295 ± 15.1 nm, an encapsulation efficiency of 72.52%, and a polydispersity index of 0.292 ± 0.07. Scanning electron microscopy confirmed the spherical and isolated nature of the PLGA-rOmpA nanoparticles. The protective efficacy in A. hydrophila-infected zebrafish after oral administration of the nanovaccine resulted in relative percentage survival of 77.7. Gene expression studies showed significant upregulation of immune genes in the vaccinated fish. The results demonstrate the usefulness of oral administration of nanovaccine-loaded rOmpA as a potential vaccine since it induced a robust immune response and conferred adequate protection against A. hydrophila in zebrafish, Danio rerio.

Immunomodulatory, antioxidant, and growth-promoting activities of dietary fermented Moringa oleifera in Nile tilapia (Oreochromus niloticus) with in-vivo protection against Aeromonas hydrophila.

BACKGROUND: Moringa oleifera, a well-known medicinal plant, has been used in aquafeed as a dietary supplement. Based on previous studies, insufficient research is available on the dietary supplementation of Nile tilapia with M. oleifera leaf and seed mixtures, specifically the fermented form. Therefore, this study aimed to investigate the efficacy of fermented (FMO) versus non-fermented M. oleifera (MO) leaf and seed mixtures on immunological parameters, antioxidant activity, growth performance, and resistance to A. hydrophila infection after a 30-day feeding trial on Nile tilapia. METHODS: A total of 180 fingerlings were randomly divided into four groups in addition to the control group (36 fish each, in triplicate). Fish in the tested groups were fed on basal diet supplemented with MO5%, MO10%, FMO5%, and FMO10%, while those in control were fed on basal diet only. After the feeding trial, fish were challenged with A. hydrophila. The immunomodulatory activity of M. oleifera was evaluated in terms of phagocytic and lysozyme activities, immune-related cytokines and IgM gene expression. Antioxidants, and growth-promoting activities were also assessed. RESULTS: The results revealed that fish supplemented FMO markedly in FMO10% group followed by FMO5%, exhibited significant (P < 0.05) improvement in the tested immunological, hepatic antioxidants, and growth performance parameters. Furthermore, the highest survival rate post-challenge with mild clinical symptoms, and the lowest A. hydrophila bacterial count were reported in these groups. Meanwhile, MO10%-supplementation exhibited the opposite trend. CONCLUSIONS: The study' conclusion suggests that fermented M. oleifera leaf and seed mixture is a promising growth-promoting and immunostimulatory feed-additive candidate for Nile tilapia and could reduce the losses caused by A. hydrophila infection.

Integrating 16S rRNA profiling and in-silico analysis for an epitope-based vaccine strategy against Achromobacter xylosoxidans infection.

Achromobacter xylosoxidans is an aerobic, catalase-positive, non-pigment-forming, Gram-negative, and motile bacterium. It potentially causes a wide range of human infections in cystic fibrosis and non-cystic fibrosis patients. However, developing a safe preventive or therapeutic solution against A. xylosoxidans remains challenging. This study aimed to construct an epitope-based vaccine candidate using immunoinformatic techniques. A. xylosoxidans was isolated from an auto workshop in Lahore, and its identification was confirmed through 16S rRNA amplification and bioinformatic analysis. Two protein targets with GenBank accession numbers AKP90890.1 and AKP90355.1 were selected for the vaccine construct. Both proteins exhibited antigenicity, with scores of 0.757 and 0.580, respectively and the epitopes were selected based on the IC50 value using the ANN 4.0 and NN-align 2.3 epitope prediction method for MHC I and MHC II epitopes respectively and predicted epitopes were analyzed for antigenicity, allergenicity and pathogenicity. The vaccine construct demonstrated structural stability, thermostability, solubility, and hydrophilicity. The vaccine produced 250 B-memory cells per mm3 and approximately 16,000 IgM + IgG counts, indicating an effective immune response against A. xylosoxidans. Moreover, the vaccine candidate interacted stably with toll-like receptor 5, a pattern recognition receptor, with a confidence score of 0.98. These results highlight the potency of the designed vaccine candidate, suggesting its potential to withstand rigorous in vitro and in vivo clinical trials. This epitope-based vaccine could serve as the first preventive immunotherapy against A. xylosoxidans infections, addressing this bacterium's health and financial burdens. The findings demonstrate the value of employing immunoinformatic tools in vaccine development, paving the way for more precise and tailored approaches to combating microbial threats.

Carbapenem-resistant Gram-negative bacteria (CR-GNB) in ICUs: resistance genes, therapeutics, and prevention - a comprehensive review.

Intensive care units (ICUs) are specialized environments dedicated to the management of critically ill patients, who are particularly susceptible to drug-resistant bacteria. Among these, carbapenem-resistant Gram-negative bacteria (CR-GNB) pose a significant threat endangering the lives of ICU patients. Carbapenemase production is a key resistance mechanism in CR-GNB, with the transfer of resistance genes contributing to the extensive emergence of antimicrobial resistance (AMR). CR-GNB infections are widespread in ICUs, highlighting an urgent need for prevention and control measures to reduce mortality rates associated with CR-GNB transmission or infection. This review provides an overview of key aspects surrounding CR-GNB within ICUs. We examine the mechanisms of bacterial drug resistance, the resistance genes that frequently occur with CR-GNB infections in ICU, and the therapeutic options against carbapenemase genotypes. Additionally, we highlight crucial preventive measures to impede the transmission and spread of CR-GNB within ICUs, along with reviewing the advances made in the field of clinical predictive modeling research, which hold excellent potential for practical application.

Oral feed-based administration of phage cocktail protects rohu fish (Labeo rohita) against Aeromonas hydrophila infection.

Aeromonas hydrophila is one of the major freshwater fish pathogens. In the current study, a cocktail of D6 and CF7 phages was given orally to Labeo rohita to assess phage survival in fish organs as well as to determine the therapeutic efficacy of phage treatment against fish mortality caused by A. hydrophila. In the phage-coated feed, prepared by simple spraying method, phage counts were quite stable for up to 2 months with a decline of ≤ 0.23 log10 and ≤ 1.66 log10 PFU/g feed during 4 oC and room temperature storage. Throughout the experimental period of 7 days, both phages could be detected in the gut of fish fed with phage-coated feed. Besides, both CF7 and D6 phages were also detected in fish kidneys indicating the ability of both the phage to cross the intestinal barrier. During challenge studies with LD50 dose of A. hydrophila, phage cocktail doses of 1 × 106 - 1 × 108 PFU/g feed prevented the mortality in L. rohita with relative percentage survival (RPS) of 8.7-65.2. When challenged with LD90 dose of A. hydrophila, an RPS value of 28.6 was obtained at a phage cocktail dose of 1 × 108 PFU/g feed. The RPS data showed that orally-fed phage cocktail protected the fish against the mortality caused by A. hydrophila in a dose-dependent manner. Simple practical approaches for phage cocktail development, medicated feed preparation and oral administration along with phage survival and protection data make the current study useful for farmer-level application.

Rhodobacter sphaeroides supplementation improves defense ability of Chinese mitten crab Eriocheir sinensis against Shewanella putrefaciens infection via intestinal flora and metabolism regulation.

Shewanella putrefaciens is a vital bacterial pathogen implicated in serious diseases in Chinese mitten crab Eriocheir sinensis. Yet the use of probiotics to improve the defense ability of E. sinensis against S. putrefaciens infection remains poorly understood. In the present study, the protective effect of dietary R. sphaeroides against S. putrefaciens infection in E. sinensis was evaluated through antioxidant capability, immune response, and survival under bacterial challenge assays, and its protective mechanism was further explored using a combination of intestinal flora and metabolome assays. Our results indicated that dietary R. sphaeroides could significantly improve immunity and antioxidant ability of Chinese mitten crabs, thereby strengthening their disease resistance with the relative percentage survival of 81.09% against S. putrefaciens. In addition, dietary R. sphaeroides could significantly alter the intestinal microbial composition and intestinal metabolism of crabs, causing not only the reduction of potential threatening pathogen load but also the increase of differential metabolites in tryptophan metabolism, pyrimidine metabolism, and glycerophospholipid metabolism. Furthermore, the regulation of differential metabolites such as N-Acetylserotonin positively correlated with beneficial Rhodobacter could be a potential protection strategy for Shewanella infection. To the best of our knowledge, this is the first study to illustrate the protective effect and mechanism of R. sphaeroides supplementation to protect E. sinensis against S. putrefaciens infection.

Impact of Sel-Plex® dietary supplementation on growth performance, physiological response, oxidative status, and immunity-linked gene expression in Nile tilapia (Oreochromis niloticus) fingerlings challenged with Aeromonas hydrophila.

Background: Organic selenium (Sel-Plex®) supplementation holds considerable promise for improving the effectiveness of fish production. Aim: This experiment was accomplished to judge the potential benefits of Sel-Plex® nutritional additive on growth outcomes, physiological response, oxidative status, and immunity-linked gene expression in Nile tilapia (Oreochromis niloticus) fingerlings exposed to bacterial infection with Aeromonas hydrophila. Methods: Utilizing a basal diet of 30% protein, four experimental diets were prepared, each of which contained Sel-Plex® at concentrations of 0.0, 0.5, 1, and 2 mg/kg, respectively. Three replicates of 20 fish/treatment were used using 240 healthy Nile tilapia fingerlings. Fish were placed in 12 glass aquariums and separated into 4 groups at random. For the entire span of 8 weeks, diets were admitted to fish at a 3% rate of fish biomass/aquarium. After the feeding trial, pathogenic A. hydrophila was intraperitoneally injected into fish of each treatment, and fish were observed for 15 days to track the survival rate (SR) after the challenge. Results: Growth performance, physiological response, immunological parameters (phagocytic activity, phagocytic index, and lysozyme), and antioxidant parameters [catalase, superoxide dismutase (SOD), malondialdehyde, and glutathione peroxidase (GPx)] were noticeably improved in Sel-Plex® treated groups. Moreover, Sel-Plex® increased gene expression linked with the immune system in the liver (tumor necrosis factor-alpha and interleukin 1ß), to growth (insulin-like growth factor 1 and growth hormone receptor), and antioxidants (SOD and GPx). Under pathogen-challenge conditions, the employed dietary Sel-Plex® supplementation could successfully lower fish oxidative stress, offering a potential preventive additive for Nile tilapia instead of antibiotics. On the other hand, Sel-Plex® significantly enhanced each of three intestinal morphological measurements (villus width, villus length, and crypt depth), demonstrating the greatest influence on the improvement of intestinal structure overall. In the Nile tilapia control group, the infection with A. hydrophila caused noticeable degenerative alterations in the gut, hepatopancreas, spleen, and posterior kidney. The severity of the lesion was significantly reduced and significantly improved with higher Sel-Plex® concentrations. Sel-Plex® supplemented groups had 100% SRs among the A. hydrophila-challenged groups. Conclusion: It could be advised to enrich the diets of Nile tilapia fingerlings with 1-2 mg.kg-1 of Sel-Plex® to enhance growth rate, physiological response, immunological reaction, and intestinal absorptive capacity.

Sink interventions in the ICU to reduce risk of infection or colonization with Gram-negative pathogens: a systematic review of the literature.

BACKGROUND: Healthcare-associated infections (HAIs) are a major problem in intensive care units (ICUs). The hospital water environment is a potential reservoir for Gram-negative bacteria (GNB), and it has been shown that contaminated sinks contribute to the spread of GNB in outbreak and non-outbreak settings. This study aimed to investigate which sink interventions may reduce GNB infection and colonization rates in the ICU. METHODS: A database search (MEDLINE via PubMed, EMBASE via Ovid and ClinicalTrials.gov) was undertaken without restrictions on language or date of publication. Studies of any design were included if they described an intervention on the water fixtures in patient rooms, and presented data about HAI or colonization rates in non-outbreak settings. Acquisition (infection and/or colonization) rates of GNB and Pseudomonas aeruginosa were analysed as outcomes. RESULTS: In total, 4404 records were identified. Eleven articles were included in the final analysis. No randomized controlled trials were included in the analysis, and all studies were reported to have moderate to serious risk of bias. Removing sinks and applying filters on taps had a significant impact on GNB acquisition, but there was high heterogeneity among reported outcomes and sample size among the studies. CONCLUSION: Few studies have investigated the association of sinks in patient rooms with healthcare-associated acquisition of GNB in non-outbreak settings. Heterogeneity in study design made it impossible to generalize the results. Prospective trials are needed to further investigate whether removing sinks from patient rooms can reduce the endemic rate of HAIs in the ICU.

Acanthopanax senticosus cultures fermented by Lactobacillus rhamnosus enhanced immune response through improvement of antioxidant activity and inflammation in crucian carp (Carassius auratus).

Lactic acid bacteria (LAB) have been recognized as safe microorganism that improve micro-flora disturbances and enhance immune response. A well-know traditional herbal medicine, Acanthopanax senticosus (As) was extensively utilized in aquaculture to improve growth performance and disease resistance. Particularly, the septicemia, skin wound and gastroenteritis caused by Aeromonas hydrophila threaten the health of aquatic animals and human. However, the effects of probiotic fermented with A. senticosus product on the immune regulation and pathogen prevention in fish remain unclear. Here, the aim of the present study was to elucidate whether the A. senticosus fermentation by Lactobacillus rhamnosus improve immune barrier function. The crucian carp were fed with basal diet supplemented with L. rhamnosus fermented A. senticosus cultures at 2 %, 4 %, 6 % and 8 % bacterial inoculum for 8 weeks. After trials, the weight gain rate (WGR), specific growth rate (SGR) were significantly increased, especially in LGG-6 group. The results confirmed that the level of the CAT, GSH-PX, SOD, lysozyme, and MDA was enhanced in fish received with probiotic fermented product. Moreover, the L. rhamnosus fermented A. senticosus cultures could trigger innate and adaptive immunity, including the up-regulation of the C3, C4, and IgM concentration. The results of qRT-PCR revealed that stronger mRNA transcription of IL-1ß, IL-10, IFN-γ, TNF-α, and MyD88 genes in the liver, spleen, kidney, intestine and gills tissues of fish treated with probiotic fermented with A. senticosus product. After infected with A. hydrophila, the survival rate of the LGG-2 (40 %), LGG-4 (50 %), LGG-6 (60 %), LGG-8 (50 %) groups was higher than the control group. Meanwhile, the pathological damage of the liver, spleen, head-kidney, and intestine tissues of probiotic fermentation-fed fish could be alleviated after pathogen infection. Therefore, the present work indicated that L. rhamnosus fermented A. senticosus could be regard as a potential intestine-target therapy strategy to protecting fish from pathogenic bacteria infection.

Expression of immuno-transcriptome response in red hybrid tilapia (Oreochromis sp.) hindgut following vaccination with feed-based bivalent vaccine.

Streptococcosis and aeromoniasis are the main obstacles to sustainable tilapia production. Vaccination offered an effective method to control microbial infections. Previously, a feed-based bivalent vaccine (FBBV) containing killed whole organisms of Streptococcus agalactiae and Aeromonas hydrophila mixed with 10% palm oil was successfully developed, which provided good protection against streptococcosis and aeromoniasis in Oreochromis sp. However, the mechanisms of immunities in vaccinated fish still need clarification. Here, the hindgut transcriptome of vaccinated and control fish was determined, as the gut displays higher affinity towards antigen uptake and nutrient absorption. The efficacy of FBBV to improve fish immunity was evaluated according to the expression of immune-related genes in the vaccinated fish hindgut throughout the 8-week experimental period using RT-qPCR. The vaccinated fish hindgut at week 6 was further subjected to transcriptomic analysis due to the high expression of immune-related genes and contained killed whole organisms. Results demonstrated the expression of immune-related genes was in correlation with the presence of killed whole organisms in the vaccinated fish hindgut. Transcriptomic analysis has allowed the prediction of robust immune-related pathways, including innate and adaptive immunological responses in vaccinated fish hindgut than control fish. Pathways related to the regulation of lipid metabolism and modulation of the immune system were also significantly enriched (p ≤ .05). Overall, results offer a fundamental study on understanding the immunological response in Oreochromis sp. following vaccination with the FBBV pellet and support further application to prevent bacterial diseases in aquaculture.

Inactivated Aeromonas salmonicida impairs adaptive immunity in lumpfish (Cyclopterus lumpus).

Aeromonas salmonicida, a widely distributed aquatic pathogen causing furunculosis in fish, exhibits varied virulence, posing challenges in infectious disease and immunity studies, notably in vaccine efficacy assessment. Lumpfish (Cyclopterus lumpus) has become a valuable model for marine pathogenesis studies. This study evaluated several antigen preparations against A. salmonicida J223, a hypervirulent strain of teleost fish, including lumpfish. The potential immune protective effect of A. salmonicida bacterins in the presence and absence of the A-layer and extracellular products was tested in lumpfish. Also, we evaluated the impact of A. salmonicida outer membrane proteins (OMPs) and iron-regulated outer membrane proteins (IROMPs) on lumpfish immunity. The immunized lumpfish were intraperitoneally (i.p.) challenged with 104 A. salmonicida cells/dose at 8 weeks-post immunization (wpi). Immunized and non-immunized fish died within 2 weeks post-challenge. Our analyses showed that immunization with A. salmonicida J223 bacterins and antigen preparations did not increase IgM titres. In addition, adaptive immunity biomarker genes (e.g., igm, mhc-ii and cd4) were down-regulated. These findings suggest that A. salmonicida J223 antigen preparations hinder lumpfish immunity. Notably, many fish vaccines are bacterin-based, often lacking efficacy evaluation. This study offers crucial insights for finfish vaccine approval and regulations.

Survey on the approach to antibiotic prophylaxis in liver and kidney transplant recipients colonized with "difficult to treat" Gram-negative bacteria.

BACKGROUND: Performance of active screening for multidrug-resistant Gram-negative bacteria (MDR-GNB) and administration of targeted antibiotic prophylaxis (TAP) in colonized patients undergoing liver (LT) and/or kidney transplantation (KT) are controversial issues. METHODS: Self-administered electronic cross-sectional survey disseminated from January to February 2022. Questionnaire consisted of four parts: hospital/transplant program characteristics, standard screening and antibiotic prophylaxis, clinical vignettes asking for TAP in patients undergoing LT and KT with prior infection/colonization with four different MDR-GNB (extended-spectrum cephalosporin-resistant Enterobacterales [ESCR-E], carbapenem-resistant Enterobacterales [CRE], multidrug-resistant Pseudomonas aeruginosa [MDR-Pa], and carbapenem-resistant Acinetobacter baumannii [CRAb]). RESULTS: Fifty-five respondents participated from 14 countries, mostly infectious disease specialists (69%) with active transplant programs (>100 procedures/year for 34.5% KT and 23.6% LT), and heterogeneous local MDR-GNB prevalence from <15% (30.9%), 15%-30% (43.6%) to >30% (16.4%). The frequency of screening for ESCR-E, CRE, MDR-Pa, and CRAb was 22%, 54%, 17%, and 24% for LT, respectively, and 18%, 36%, 16%, and 11% for KT. Screening time-points were mainly at transplantation 100%, only one-third following transplantation. Screening was always based on rectal swab cultures (100%); multi-site sampling was reported in 40% of KT and 35% of LT. In LT clinical cases, 84%, 58%, 84%, and 40% of respondents reported TAP for prior infection/colonization with ESCR-E, CRE, MDR-Pa, and CRAb, respectively. In KT clinical cases, 55%, 39%, 87%, and 42% of respondents reported TAP use for prior infection/colonization with ESCR-E, CRE, MDR-Pa, and CRAb, respectively. CONCLUSION: There is a large heterogeneity in screening and management of MDR-GNB carriage in LT and KT.

Construction and characterization of Aeromonas hydrophila crp and fur deletion mutants and evaluation of its potential as live-attenuated vaccines in crucian carp.

Aeromonas hydrophila (A. hydrophila) is a typical zoonotic pathogenic bacterium that infects humans, animals, and fish. It has been reported that the Fur, a Fe2+ regulatory protein, and the Crp, a cAMP receptor protein, play important roles in bacterial virulence in many bacteria, but no research has been investigated on A. hydrophila. In this study, the Δfur and Δcrp mutant strains were constructed by the suicide plasmid method. These two mutant strains exhibited a slightly diminished bacterial growth and also were observed some alterations in the number of outer membrane proteins, and the disappearance of hemolysis in the Δcrp strain. Animal experiments of crucian carp showed that the Δfur and Δcrp mutant strains significantly decreased virulence compared to the wild-type strain, and both mutant strains were able to induce good immune responses by two kinds of administration routes of intraperitoneal immunization (i.p) and immersion immunization, and the protection rates through intraperitoneal injection of Δfur and Δcrp to crucian carp were as high as 83.3 % and 73.3 %, respectively, and immersion immunization route of Δfur and Δcrp to crucian carp provided protection as high as 40 % and 20 %, respectively. These two mutant strains showed abilities to induce changes in enzymatic activities of the non-specific enzymes SOD, LZM, AKP, and ACP in crucian carp. Together, these results indicated the Δfur and Δcrp mutants were safe and effective candidate vaccine strains, showing good protection against the wild-type A. hydrophila challenge.

Sweet orange peel waste as a feed additive in growth promoting and protective effect against Aeromonas hydrophila of juvenile bagrid catfish Mystus nemurus.

Sweet orange Citrus sinensis peel is a phytobiotic agricultural waste with bioactive compounds that have potential functional properties as a growth promoter and immune stimulator. This study aims to evaluate the dietary effects of sweet orange peel (SOP) as a feed additive on growth enhancement of juvenile bagrid catfish Mystus nemurus and their disease resistance ability against Aeromonas hydrophila infection. Four experimental diets were formulated to contain 0 (SOP0, control), 4 (SOP4), 8 (SOP8) and 12 g/kg (SOP12) SOP. After 90 d of the feeding experiment, improvement in weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio were observed in the fish fed with SOP4. While fish survival was not significantly affected, hepatosomatic and viscerosomatic indices were significantly higher in fish fed with SOP12. Muscle protein was higher in fish fed with SOP4, SOP8, and SOP12 than in control but muscle lipids showed an opposite trend. A 14-d post-challenge test against A. hydrophila revealed no significant effect on the fish survival. Nevertheless, fish fed SOP4 encountered delayed bacterial infection compared to other treatments and fish fed with SOP0 and SOP4 performed numerically better survival. Infected fish showed skin depigmentation, haemorrhagic signs at the abdomen and anus, internal bleeding, and stomach and intestine enlargement. In conclusion, SOP4 could be recommended as a growth promoter while slightly delaying A. hydrophila infection in M. nemurus.

Field validation of an antibiotic-free hoof spray to effectively treat ovine footrot by eliminating virulent Dichelobacter nodosus.

Ovine footrot caused by Dichelobacter nodosus is a highly contagious hoof disease negatively impacting animal welfare and causing major economic losses to the sheep industry. Bactericidal footbaths have shown to be an efficient treatment option and will be used in the national footrot control program in Switzerland. However, the application of footbaths is laborious and economically not sound for small flock holders. We therefore tested in a field study the Intra Repiderma spray for its applicability and efficacy to treat ovine footrot. Ten independent flocks fulfilling defined parameters (e.g. clinical signs, positive for D. nodosus, flock size) could be identified and were included in the study. Farms were visited weekly to fortnightly and clinical scores and swabs for D. nodosus real-time (rt)PCR were taken. Treatment with the Intra Repiderma spray was started after initial claw trimming at the very first visit and was carried out three times within a week. Clearly visible clinical improvement was evident after one week of treatment. Virulent D. nodosus amounts on feet declined constantly during treatment which was continued until all sheep of a flock tested rtPCR-negative (1-10 weeks). Results indicate that a highly effective improvement of clinical signs and complete elimination of virulent D. nodosus can be achieved with the spray treatment. Therefore, it is a valuable alternative to cumbersome footbaths especially for small flocks. A sustainable control of footrot and its pathogen in a successfully treated flock can be maintained by strict biosecurity measures and continued treatment as far as necessary.

Potentials of Aloe barbadensis inclusion in fish feeds on resilience to Aeromonas hydrophila infection in freshwater fish Labeo rohita.

Aquatic bacterial pathogens can cause severe economic loss in aquaculture industry. An opportunistic pathogen, Aeromonas hydrophila is responsible for Motile Aeromonas Septicemia, leading to high mortality rates in fish. The present study was focused on the efficacy of Aloe barbadensis replacing fishmeal diets on hematological, serum biochemical, antioxidant, histopathological parameters, and disease resistance against A. hydrophila infection in Labeo rohita. Isonitrogenous fishmeal replaced diets (FMR) were prepared with varying levels of A. barbadensis at D1 (0%) (control), D2 (25%), D3 (50%), D4 (75%) and D5 (100%) then fed to L. rohita. After 60 days of post-feeding, the experimental fish were challenged with A. hydrophila. Blood and organs were collected and examined at 1- and 15-days post infection (dpi). The results demonstrated that on 1 dpi, white blood cells (WBC), total protein, cholesterol and low-density lipoprotein (LDL) levels were significantly increased in D3 diet fed groups. The D2 and D3 diet fed group showed decreasing trends of serum glutamic pyruvic transaminase (SGPT) and antioxidant enzymes activity on 15 dpi. The histopathological architecture results clearly illustrated that the D3 diet fed group had given a higher protective effect by reducing the pathological changes associated with A. hydrophila infection in liver, intestine and muscle. Higher percentage of survival rate was also observed in D3 diet fed group. Therefore, the present study suggested that the dietary administration of A. barbadensis up to 50% fishmeal replacement (D3 diet) can elicit earlier antioxidant activity, innate immune response and improve survival rate in L. rohita against A. hydrophila infection.

Mechanical replication of natural fever enhances protection against Aeromonas veronii infection in a teleost fish.

There is a long-standing debate on the attributes of temperature for fish health. We recently showed that thermoregulatory programs exerted through natural behavioural fever drive molecular and cellular responses that contribute to pathogen clearance, inflammation control, and tissue repair. These offered a mechanistic basis for the survival advantage conferred through fever. Herein, we show the attributes of mechanical replication of this fever response. Central to our approach was consideration of both, the maximal temperatures naturally selected by fish after infection, as well as the dynamics of thermal changes induced through this response. Coarse replication of the febrile thermal program as well as shorter truncated thermal schedules offered immune-regulatory capacity. Most notably, these promoted induction of acute inflammation and significant enhancements to pathogen clearance. However, the coarse protocols tested only partially recapitulated enhancements to induction and control of tissue repair. Our findings highlight a promising new alternative to combat infections in fish using a natural, drug-free, sustainable approach.

The oral protective efficacy of magnolol against Aeromonas hydrophila and A. veronii infection via enhancing anti-inflammatory ability in goldfish (Carassius auratus).

Aeromonas hydrophila and A. veronii are widespread and important critical pathogenic bacteria in the aquaculture industry and cause severe economic damage. At present, magnolol has been proved to be a broad-spectrum antibacterial activity, such as A. hydrophila, Staphylococcus aureus and Streptococcus mutans. In order to explore the cause of in vivo disease resistance of magnolol and promote its safe application in aquaculture, the pathological detection and changes in immune indicators of fish after feeding with magnolol were conducted in this paper. Results showed that the diets supplemented with magnolol (3 g magnolol/kg commercial feed) significantly increase the expression level of anti-inflammatory cytokines (IL-10, TGF-ß and IL-4) in the liver of goldfish (p < .05). Additionally, the expression levels of proinflammatory cytokines (IL-1ß, IL-8 and IFN-γ) did not increase significantly. Subsequently, this study investigated the resistance of goldfish to A. hydrophila and A. veronii infection after feeding with magnolol. The results showed that the survival rates of treatment groups fed 3 g magnolol/kg commercial feed daily increased by 23.1% and 38.5% after 10 days post A. hydrophila and A. veronii (p = .0351) infection, respectively. Meanwhile, growth performance (body weight and length), major internal organs (liver, spleen, kidney and intestine) and the serum biochemistry indicators (ATL and AST) all exhibited no significant adverse effects after the goldfish fed with magnolol for 30 days. TP showed an increasing concentration in the treatment group (p < .05). Results of the mRNA expression of stress response indicated that the expression level of cyp1a and hsp70 was significantly down-regulated after a 30-day treatment (p < .05), and the two genes recovered to the similar level as the control group after a commercial feed diet. In brief, the diets supplemented with magnolol protected the host from the excessive immune response caused by A. hydrophila and A. veronii via enhancing its anti-inflammatory capacity and had no adverse effects with feeding.

Impact of carbapenem-targeted antimicrobial stewardship interventions: an interrupted time-series analysis.

BACKGROUND: The development of carbapenem-resistant Gram-negative bacilli (CR-GNB) is largely favoured by indiscriminate and prolonged carbapenem use, which is a significant contributing factor. AIM: To evaluate the impact of two carbapenem antibiotic stewardship programme interventions on both carbapenem prescriptions and the clinical isolation rates of CR-GNBs, using interrupted time-series analysis. METHODS: A time-series analysis was performed using data for carbapenem usage from a tertiary hospital in South Korea from January 2017 to July 2022. Two carbapenem antibiotic stewardship programme interventions were implemented sequentially: (i) a prospective audit and feedback (PAF) from November 2018 to April 2020 (intervention 1), and (ii) preauthorization from May 2020 to August 2020 (intervention 2). Monthly carbapenem usage and incidence of CR-GNB before and after each intervention were compared using an autoregressive integrated moving average model. FINDINGS: Implementation of PAF resulted in a significant reduction in carbapenem consumption, followed by an additional decrease after the preauthorization was implemented. The incidence of carbapenem-resistant Escherichia coli and Klebsiella pneumoniae increased after intervention 1, but there was a significant change from an increasing trend to a stationary trend after intervention 2. The incidence of carbapenem-resistant Pseudomonas aeruginosa, which had increased during the baseline period, became stationary after intervention 1. A significant decrease was observed in the incidence of carbapenem-resistant Acinetobacter baumannii during the implementation of intervention 1 and 2. CONCLUSION: This study emphasizes the importance of adopting comprehensive antibiotic management and rigorous infection control to prevent infections caused by antibiotic-resistant bacteria.

Infection control measures against multidrug-resistant Gram-negative bacteria in children and neonates.

The increase in infections caused by multidrug-resistant (MDR) Gram-negative bacteria in neonatal and pediatric intensive care units over recent years is alarming. MDR Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii have constituted the main causes of the MDR Gram-negative bacteria problem. The implementation of infection control measures such as hand hygiene, cohorting of patients, contact precautions, active surveillance and environmental cleaning could diminish their spread. Recently, water safety has been identified as a major component of infection control policies. The aim of the current review is to highlight the effectiveness of these infection control measures in managing outbreaks caused by MDR Gram-negative bacteria in neonatal and pediatric intensive care units and highlight future perspectives on the topic.