The type III secretion system (T3SS) is an important virulence factor of Gram-negative bacteria, including the genus Aeromonas, which represents a diverse group of aquatic bacteria. One member of the genus, Aeromonas schubertii, is an emerging pathogen in aquaculture, causing high mortality in snakehead fish. Infections are associated with the formation of white nodules in the internal organs, likely resulting from A. schubertii-induced apoptosis and/or necrosis. The present study investigates the type strain A. schubertii ATCC 43700, which encodes two distinct T3SSs located within Aeromonas pathogenicity islands 1 and 2, referred here to as API1 and API2. We analyzed their role in A. schubertii-induced cytotoxicity and identified novel T3SS effector proteins. Infections of HeLa cells revealed that API1, but not API2, mediates cytotoxicity and induces both apoptotic and necrotic cell death. Moreover, proteomic analysis identified seven candidate effectors secreted by the API1 injectisome. These included two previously described effectors, AopH and AopO from A. salmonicida, as well as five novel effectors named AopI, AopJ, AopL, AopT, and AopU, whose injection into host cells was validated using a split luciferase reporter system. Functional characterization showed that AopL, a homolog of Vibrio parahaemolyticus VopQ, induces caspase-3/-7-independent necrosis, while AopI, a homolog of ExoY from Pseudomonas aeruginosa, suppresses caspase-3/-7 activation and necrosis, revealing a pro-survival function. These results demonstrate the critical role of the API1 injectisome in A. schubertii-induced cytotoxicity and provide experimental identification of novel Aeromonas effectors that cooperate to fine-tune host cell cytotoxicity.

• Klíčová slova
• Aeromonas, Aeromonas schubertii, ExoY, VopQ, cytotoxicity, type III secretion system effectors,
• MeSH
• Aeromonas * genetika   patogenita   fyziologie   MeSH
• apoptóza MeSH
• bakteriální proteiny * metabolismus   genetika   MeSH
• faktory virulence * metabolismus   genetika   MeSH
• gramnegativní bakteriální infekce * mikrobiologie   veterinární   MeSH
• HeLa buňky MeSH
• lidé MeSH
• nemoci ryb * mikrobiologie   MeSH
• sekreční systém typu III * metabolismus   genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny * MeSH
• faktory virulence * MeSH
• sekreční systém typu III * MeSH

The role of aeromonads as contributors to gastrointestinal pathology remains controversial. The aim of this study was to analyse the clinical characteristics and risk factors for the acquisition of an enteric infection by Aeromonas spp. in patients with digestive or nephrological diseases. The method user for the study comprised a retrospective review of the clinical history of all patients in whom Aeromonas spp. was isolated in faeces. The study period included in samples arriving at the microbiology service of the Marqués de Valdecilla University Hospital, from 2016 to 2022. The results showed that there was an increase in the more virulent Aeromonas species in the patients studied. The most common chronic diseases were cancer, inflammatory bowel disease and alcoholic cirrhosis, as well as biliary involvement in acute cases. In conclusión, Aeromonas is a genus to consider in patients with diarrhoea and hepatonephrological involvement.

• Klíčová slova
• Aeromonas spp., Alcoholic cirrhosis, Diarrhoea, Inflammatory bowel disease, MALDI-TOF MS,
• MeSH
• Aeromonas * izolace a purifikace   patogenita   klasifikace   genetika   MeSH
• dospělí MeSH
• feces mikrobiologie   MeSH
• gramnegativní bakteriální infekce * mikrobiologie   epidemiologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• průjem mikrobiologie   MeSH
• retrospektivní studie MeSH
• rizikové faktory MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

INTRODUCTION: Red blood cells (RBCs), also known as erythrocytes, are underestimated in their role in the immune system. In mammals, erythrocytes undergo maturation that involves the loss of nuclei, resulting in limited transcription and protein synthesis capabilities. However, the nucleated nature of non-mammalian RBCs is challenging this conventional understanding of RBCs. Notably, in bony fishes, research indicates that RBCs are not only susceptible to pathogen attacks but express immune receptors and effector molecules. However, given the abundance of RBCs and their interaction with every physiological system, we postulate that they act in surveillance as sentinels, rapid responders, and messengers. METHODS: We performed a series of in vitro experiments with Cyprinus carpio RBCs exposed to Aeromonas hydrophila, as well as in vivo laboratory infections using different concentrations of bacteria. RESULTS: qPCR revealed that RBCs express genes of several inflammatory cytokines. Using cyprinid-specific antibodies, we confirmed that RBCs secreted tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ). In contrast to these indirect immune mechanisms, we observed that RBCs produce reactive oxygen species and, through transmission electron and confocal microscopy, that RBCs can engulf particles. Finally, RBCs expressed and upregulated several putative toll-like receptors, including tlr4 and tlr9, in response to A. hydrophila infection in vivo. DISCUSSION: Overall, the RBC repertoire of pattern recognition receptors, their secretion of effector molecules, and their swift response make them immune sentinels capable of rapidly detecting and signaling the presence of foreign pathogens. By studying the interaction between a bacterium and erythrocytes, we provide novel insights into how the latter may contribute to overall innate and adaptive immune responses of teleost fishes.

• Klíčová slova
• Aeromonas hydrophila (A. hydrophila), Cyprinus carpio, bacteria, cytokines, engulfment, inflammation, red blood cell (RBC), teleost fish,
• MeSH
• Aeromonas hydrophila * imunologie   MeSH
• cytokiny * metabolismus   imunologie   MeSH
• erytrocyty * imunologie   metabolismus   MeSH
• fagocytóza imunologie   MeSH
• gramnegativní bakteriální infekce * imunologie   MeSH
• kapři * imunologie   mikrobiologie   MeSH
• nemoci ryb * imunologie   mikrobiologie   MeSH
• PAMP struktury imunologie   MeSH
• přirozená imunita MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cytokiny * MeSH
• PAMP struktury MeSH

Bacterial diseases are common in ornamental fish, more frequently associated with ubiquitous bacteria from the aquarium environment. The disease can lead to fish mortality and cause high economic losses if not rapidly controlled. The aim of this study was to identify the main causative bacterial agents of infection in ornamental fish with different clinical signs. A total of 126 freshwater fish, from 12 families and 38 species, with clinical signs were collected in a wholesaler in São Paulo, SP, Brazil. Samples were taken from the eye, skin ulcers, kidneys, and gills, plated on MacConkey, CHROMagar Orientation, and blood agar and incubated under aerobic and anaerobic conditions. Bacterial identification was performed by MALDI-TOF mass spectrometry. From the 126 studied animals, 112 were positive for bacterial isolation. Among the positive animals, 32.1% presented infection caused by a single bacterial species, while in the remaining 67.9%, two to six different bacterial species were identified. A total of 259 bacterial strains were obtained and classified among 46 bacterial species. The species of higher frequency were Aeromonas veronii (26.3%), Aeromonas hydrophilla (16.2%), Shewanella putrefaciens (7.3%), Citrobacter freundii (8.1%), Vibrio albensis (5.8%), and Klebsiella pneumoniae (4.2%). MALDI-TOF MS showed to be a rapid method for diagnosis of bacterial disease outbreaks in ornamental fish establishments.

• Klíčová slova
• Animal health, Bacterial disease, Diagnosis in fish, Fish disease,
• MeSH
• Aeromonas * MeSH
• lidé MeSH
• nemoci ryb * MeSH
• ryby MeSH
• sladká voda MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Brazílie MeSH

Biofloc technology is increasingly becoming the most promising aquaculture tool especially in places where water is scarce and the land is very expensive. The dynamics of water quality, as well as plankton and microbial abundance, are collectively necessary for successful fish farming. The prospective use of jaggery as a potential carbon source and its influence on water quality, growth performance, innate immunity, serum bactericidal capacity, and disease resistance to Aeromonas hydrophila was investigated in Oreochromis niloticus. A completely randomized design was used in triplicates, where the control group was reared in a water system with no carbon source, while T1, T2, and T3 groups were raised in biofloc systems at C:N ratios of C:N12, C:N15, and C:N20, respectively. Water specimens were collected daily and fortnightly, while blood, serum, and head kidneys were collected at 75 days of experimental period for further analysis. TAN, nitrite, and ammonia values were considerably reduced, while the TSS values elevated significantly in all treated groups compared to the control. Jaggery-based biofloc system (JB-BFT) has a pronounced effect on hematological and growth performance parameters rather than control. Similarly, serum antioxidants, lysozyme, protease, antiprotease and bactericidal capacity were significantly increased (p < 0.05) in the treated groups in a dose-dependent manner. LYZ, TNF-α, and IL-1β genes were upregulated in proportion to C:N ratios with the highest fold in C:N20. Furthermore, fish treated with JB-BFT presented lower cumulative mortalities and better relative levels of production (RLP) after experimental challenge with A. hydrophila compared to control. In conclusion, JB-BFT has a robust influence on Nile tilapia (O. niloticus) innate immunity through favorable innovation of various immune-cells and enzymes as well as upregulating the expression levels of immune-related genes. This study offers jaggery as a new carbon source with unique properties that satisfy all considerations of biofloc technology in an eco-friendly manner.

• Klíčová slova
• Biofloc, Experimental challenge, Innate immunity, Jaggery powder, Nile tilapia,
• MeSH
• Aeromonas hydrophila fyziologie   MeSH
• cichlidy genetika   růst a vývoj   imunologie   MeSH
• dusík analýza   MeSH
• gramnegativní bakteriální infekce imunologie   veterinární   MeSH
• kvalita vody * MeSH
• nemoci ryb imunologie   MeSH
• odolnost vůči nemocem * účinky léků   MeSH
• rostlinné extrakty aplikace a dávkování   MeSH
• technologie MeSH
• uhlík analýza   MeSH
• vodní hospodářství přístrojové vybavení   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dusík MeSH
• Gur MeSH Prohlížeč
• rostlinné extrakty MeSH
• uhlík MeSH

Out of six samples of wastewater produced in the dairy industry, taken in 2017 at various places of dairy operations, 86 bacterial strains showing decarboxylase activity were isolated. From the wastewater samples, the species of genera Staphylococcus, Lactococcus, Enterococcus, Microbacterium, Kocuria, Acinetobacter, Pseudomonas, Aeromonas, Klebsiella and Enterobacter were identified by the MALDI-TOF MS and biochemical methods. The in vitro produced quantity of eight biogenic amines (BAs) was detected by the HPLC/UV-Vis method. All the isolated bacteria were able to produce four to eight BAs. Tyramine, putrescine and cadaverine belonged to the most frequently produced BAs. Of the isolated bacteria, 41% were able to produce BAs in amounts >100 mg L-1. Therefore, wastewater embodies a potential vector of transmission of decarboxylase positive microorganisms, which should be taken into consideration in hazard analyses within foodstuff safety control. The parameters of this wastewater (contents of nitrites, nitrates, phosphates, and proteins) were also monitored.

• Klíčová slova
• bacteria, biogenic amines, decarboxylase activity, wastewater,
• MeSH
• Acinetobacter MeSH
• Aeromonas MeSH
• biogenní aminy chemie   MeSH
• chemické látky znečišťující vodu chemie   izolace a purifikace   MeSH
• Enterobacter MeSH
• Enterococcus MeSH
• karboxylyasy chemie   MeSH
• Klebsiella MeSH
• Lactobacillus MeSH
• Lactococcus MeSH
• Microbacterium MeSH
• mikrobiologie vody MeSH
• mlékárenství * MeSH
• odpadní voda analýza   mikrobiologie   MeSH
• Pediococcus MeSH
• Pseudomonas MeSH
• spektrofotometrie ultrafialová MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
• Staphylococcus MeSH
• Streptococcus MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Evropa MeSH
• Názvy látek
• biogenní aminy MeSH
• chemické látky znečišťující vodu MeSH
• karboxylyasy MeSH
• odpadní voda MeSH

Pectinatella magnifica is an invasive freshwater bryozoan that has expanded in many localities worldwide, including fishing areas. It contains microbial communities, predominantly consisting of Aeromonas bacteria that are frequently associated with fish infections. The objective of this study was to investigate the potential pathogenicity of Aeromonas spp. associated with P. magnifica and evaluate the health risks for fish. Aeromonas strains were isolated from P. magnifica (101 strains) and from surrounding water (29 strains) in the South Bohemian region and investigated for the presence of 14 virulence-associated genes using PCR. We demonstrated high prevalence of phospholipase GCAT, polar flagellin, enolase, DNAse, aerolysin/cytotoxic enterotoxin, serine protease and heat-stable cytotonic enterotoxin-coding genes. Further, all twelve isolates that were analysed for cytotoxicity against intestinal epithelial cells were found to be cytotoxic. Six of the isolates were also tested as co-cultures composed of pairs. Enhanced cytotoxicity was observed when the pair was composed of strains from different species. In conclusion, P. magnifica is colonized by Aeromonas strains that have a relatively high prevalence of virulence-associated genes and the ability to provoke disease. Results also suggest a possibly increased risk arising from mixed infections.

• Klíčová slova
• Aeromonas, Pectinatella magnifica, cytotoxicity, pathogenicity, virulence factors,
• MeSH
• Aeromonas genetika   patogenita   MeSH
• bakteriální proteiny genetika   MeSH
• Bryozoa mikrobiologie   MeSH
• enterotoxiny genetika   MeSH
• faktory virulence genetika   MeSH
• sladká voda MeSH
• virulence MeSH
• vodní hospodářství MeSH
• zavlečené druhy MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• bakteriální proteiny MeSH
• enterotoxiny MeSH
• faktory virulence MeSH

Karst rivers are of great interest for commercial fishing and aquaculture, yet they are quite vulnerable aquatic environments because the permeable karst rocks do not effectively filter out contaminants. To understand the current state of karst rivers water quality, we analysed the physico-chemical and microbiological parameters, focusing on antibiotic pollution and the emergence of antibiotic-resistant microbes of three such rivers in Croatia. Water quality varied between classes I and II across sampling sites, and the numbers of total coliforms, enterococci and heterotrophic bacteria varied substantially among sites. Swabs from fish gills, spleen, liver and kidneys were cultured and 94 isolates identified by MALDI-TOF mass spectrometry. The predominant genus was Aeromonas (42.5% of all identified isolates), known for its adaptability to polluted environments and its frequent association with antibiotic resistance. Of the selected Aeromonas isolates known as most pathogenic, half were resistant to at least three antibiotic categories. The Enterobacteriaceae family was represented by the greatest number of genera, most of which are pathogenic for humans and animals and are spoilage bacteria for fish. The results of this study highlight the extent of antibiotic contamination in aquatic environments and the increasing threat of pathogenic and spoilage bacteria in traditionally high-quality karst rivers.

• MeSH
• Aeromonas * genetika   MeSH
• antibakteriální látky farmakologie   MeSH
• lidé MeSH
• mikrobiální testy citlivosti MeSH
• řeky * MeSH
• voda MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Černé moře MeSH
• Chorvatsko MeSH
• Názvy látek
• antibakteriální látky MeSH
• voda MeSH

Flumequine was nano-immobilized by self-assembly on iron oxide nanoparticles, called surface active maghemite nanoparticles (SAMNs). The binding process was studied and the resulting core-shell nanocarrier (SAMN@FLU) was structurally characterized evidencing a firmly immobilized organic canopy on which the fluorine atom of the antibiotic was exposed to the solvent. The antibiotic efficacy of the SAMN@FLU nanocarrier was tested on a fish pathogenic bacterium (Aeromonas veronii), a flumequine sensitive strain, in comparison to soluble flumequine and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were assessed. Noteworthy, the MIC and MBC of soluble and nanoparticle bound drug were superimposable. Moreover, the interactions between SAMN@FLU nanocarrrier and microorganism were studied by transmission electron microscopy evidencing the ability of the complex to disrupt the bacterial wall. Finally, a preliminary in vivo test was provided using Daphnia magna as animal model. SAMN@FLU was able to protect the crustacean from the fatal consequences of a bacterial infection and showed no sign of toxicity. Thus, in contrast with the strength of the interaction, nano-immobilized FLU displayed a fully preserved antimicrobial activity suggesting the crucial role of fluorine in the drug mechanism of action. Besides the importance for potential applications in aquaculture, the present study contributes to the nascent field of nanoantibiotics.

• Klíčová slova
• Aeromonas veronii, Daphnia magna, Flumequine, Fluoroquinolones, Iron oxide nanoparticles, Nanoantibiotics,
• MeSH
• Aeromonas veronii účinky léků   MeSH
• antibakteriální látky chemie   farmakologie   MeSH
• Daphnia účinky léků   mikrobiologie   MeSH
• fluorochinolony chemie   farmakologie   MeSH
• magnetické nanočástice chemie   MeSH
• mikrobiální testy citlivosti MeSH
• molekulární struktura MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• flumequine MeSH Prohlížeč
• fluorochinolony MeSH
• magnetické nanočástice MeSH

p38 mitogen-activated protein kinase (MAPK) is an important protein which plays a key role in regulating the innate immunity, so exploring its molecular characterization is helpful in understanding the resistance against microbial infections in cultured fish. Here, a full-length cDNA of p38 MAPK was cloned from liver of blunt snout bream (Megalobrama amblycephala) which covered 2419 bp with an open reading frame of 1086 bp encoding 361 amino acids. p38 MAPK contained the characteristic structures of Thr-Gly-Tyr (TGY) motif and substrate binding site Ala-Thr-Arg-Trp (ATRW), which are conserved in MAPK family. To investigate p38 MAPK functions, two in vivo experiments were carried out to examine its expression following ammonia exposure and bacterial challenge. Also, an in vitro experiment was conducted to assess the role of p38 MAPK in inflammation of primary hepatocytes induced by lipopolysaccharide (LPS). The results showed the ubiquitous expression of p38 MAPK in all the tested tissues with varying levels. p38 MAPK mRNA expression was significantly up-regulated by ammonia stress and Aeromonas hydrophila challenge, and altered in a time-dependent manner. Moreover, the results indicated that the inflammatory response induced by LPS in hepatocytes is p38 MAPK dependent as knockdown of p38 MAPK using siRNA technology depressed the expression of IL-1β and IL-6. The findings in this study showed that p38 MAPK has anti-stress property, and plays key role in protection against bacterial infection and inflammation in blunt snout bream.

• Klíčová slova
• Aeromonas hydrophila challenge, Ammonia stress, Blunt snout bream, Lipopolysaccharide, p38 MAPK,
• MeSH
• Aeromonas hydrophila fyziologie   MeSH
• amoniak škodlivé účinky   MeSH
• buněčná imunita genetika   MeSH
• Cyprinidae genetika   imunologie   MeSH
• fylogeneze MeSH
• gramnegativní bakteriální infekce imunologie   MeSH
• lipopolysacharidy farmakologie   MeSH
• mitogenem aktivované proteinkinasy p38 chemie   genetika   imunologie   MeSH
• náhodné rozdělení MeSH
• nemoci ryb imunologie   MeSH
• přirozená imunita genetika   MeSH
• regulace genové exprese imunologie   MeSH
• rybí proteiny chemie   genetika   imunologie   MeSH
• sekvence aminokyselin MeSH
• sekvence nukleotidů MeSH
• sekvenční seřazení veterinární   MeSH
• stanovení celkové genové exprese veterinární   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• amoniak MeSH
• lipopolysacharidy MeSH
• mitogenem aktivované proteinkinasy p38 MeSH
• rybí proteiny MeSH