Aeromonas Strains Research Articles

High Occurrence of Multiple-Drug Resistance Mediated by Integron in Aeromonas Isolated from Fish-Livestock Integrated Farms

Fish-livestock integrated farming is a traditional practice in South China and Southeast Asia. The administration of antimicrobial agents in livestock may potentially facilitate the spread of antimicrobial resistance to aquaculture through the drainage of livestock manure. Aeromonas spp. are fish pathogens that are the predominant bacteria in water bodies. The aim of this study was to characterize multiple-drug-resistantAeromonas spp. isolated from integrated and nonintegrated fish-livestock farms and to investigate the occurrence of class 1 integrons. Of the 481 Aeromonas strains examined in this study, isolates from pig manure, fish, and environmental samples from pig-fish or goose-fish integrated farms were significantly more resistant to various antimicrobial agents than those from nonintegrated farms P < 0.05 . High rates of resistance to nalidixic acid and sulfamonomethoxine were observed in the isolates from the integrated farm. Fifty Aeromonas isolates (10.4%) from integrated farms contained class 1 integrons. In addition, 96.0% (48/50) of the integron-positive strains displayed multiple-drug resistance. Ten types of gene cassette arrays were determined by sequencing, including dfrA17, dfrA12-orfF-aadA2, catB8, dfrB4-catB3-aadA1, aac6(6′)-Ib-cr-arr-3, aac-II-blaOXA-21-catB3, aar2-aacA4-drfA1-orfC, aac(6′)-Ib-cr, dfrA15, and dfrB4-catB3-blaOXA-10-aadA1. Notably, among the 50 integron-positive isolates, twenty isolates showed integrons located in plasmids, which may facilitate the transmission of resistance in integrated farms. Our investigation confirmed the high prevalence of multiple antimicrobial resistances mediated by class 1 integrons in Aeromonas isolates from integrated farms. Therefore, it is necessary to establish a risk assessment method for antimicrobial resistance in aquaculture.

Evaluation of immunostimulating and antibacterial properties of the AQUATAN feed additive in the rainbow trout (Parasalmo mykiss irideus)

The article presents the results of research work on testing the effect of AQUATAN, a feed additive based on hydrolysable ellagitannins (extract of sweet chestnut wood, Castanea sativa Mill), on the rainbow trout. Experimental tests conducted for 93 days showed that AQUATAN at a dose of 2 g/kg introduced into the diet of the trout had an immunostimulating and antibacterial effect. There was a positive trend towards an increase in measurements of red blood cells (haemoglobin levels, RBC count) in the rainbow trout. An increase in the percentage of neutrophils, active phagocytic cells involved in the cellular component of immune system and performing phagocytosis and lysis of foreign agents, was revealed. The fish receiving the feed additive showed lower contamination of organs and blood with bacterial microflora. In the microbiocenosis, the number of isolated bacteria was two times lower compared to the fish that did not receive AQUATAN. Notably, there were no highly pathogenic Aeromonas strains, which are potential causative agents of aeromonosis or bacterial haemorrhagic septicaemia in fish, as well as Pseudomonadaceae (causative agents of pseudomonosis), Staphylococcus, Moraxella or coliform bacteria. Given the slow manifestation of the immunostimulating effect, regular use of the AQUATAN feed additive in the diet of the rainbow trout is advisable.

Hiding in Plain Sight: Characterization of Aeromonas Species Isolated from a Recreational Estuary Reveals the Carriage and Putative Dissemination of Resistance Genes.

Antimicrobial resistance (AMR) has become one of the greatest challenges worldwide, hampering the treatment of a plethora of infections. Indeed, the AMR crisis poses a threat to the achievement of the United Nations' Sustainable Development Goals and, due to its multisectoral character, a holistic approach is needed to tackle this issue. Thus, the investigation of environments beyond the clinic is of utmost importance. Here, we investigated thirteen strains of antimicrobial-resistant Aeromonas isolated from an urban estuary in Brazil. Most strains carried at least one antimicrobial resistance gene and 11 carried at least one heavy metal resistance gene. Noteworthy, four (30.7%) strains carried the blaKPC gene, coding for a carbapenemase. In particular, the whole-genome sequence of Aeromonas hydrophila strain 34SFC-3 was determined, revealing not only the presence of antimicrobial and heavy metal resistance genes but also a versatile virulome repertoire. Mobile genetic elements, including insertion sequences, transposons, integrative conjugative elements, and an IncQ1 plasmid were also detected. Considering the ubiquity of Aeromonas species, their genetic promiscuity, pathogenicity, and intrinsic features to endure environmental stress, our findings reinforce the concept that A. hydrophila truly is a "Jack of all trades'' that should not be overlooked under the One Health perspective.

ANTIMICROBIAL POTENTIAL OF EXTRACT DERIVED FROM THE LEAVES OF FICUS VILLOSA BLUME AGAINST SOME FISH PATHOGENIC STRAINS

The use of natural compounds can be found in many species of plants, and this holds much antimicrobial potential against fish pathogens in animal husbandry and fish farmers. In the current study, we studied the antimicrobial activity of the ethanolic extract derived from the leaves of F. villosa against the Aeromonas species: A. sobria, A. hydrophila, and A. salmonicida subsp. salmonicida, as well as Serratia liquefaciens, Yersinia ruckeri, Pseudomonas fluorescens, Shewanella putrefaciens to evaluate the possible use of this plant in preventing infections caused by these fish pathogens in aquaculture. The current study was conducted as a part of an ongoing project between five universities undertaken in the frame of a cooperation program aimed at the assessment of medicinal properties of tropical and subtropical plants. The leaves of F. villosa, cultivated under glasshouse conditions, were sampled at M.M. Gryshko National Botanic Garden (NBG), National Academy of Science of Ukraine. The Aeromonas strains used in our studies were Aeromonas hydrophila (K886), Aeromonas sobria (K825) and Aeromonas salmonicida subsp. salmonicida (St30). These microorganisms originated from the bacterial strain collection of the Department of Fish Diseases at the National Veterinary Research Institute in Puławy, Poland, and had been isolated from fish of two farmed freshwater species exhibiting clinical signs of disease: common carp (Cyprinus carpio L.) (K886 and K825) and rainbow trout (Oncorhynchus mykiss Walbaum) (St30). Bacteria Serratia liquefaciens, Yersinia ruckeri, Pseudomonas fluorescens, Shewanella putrefaciens were isolated both from apparently healthy rainbow trout (Oncorhynchus mykiss Walbaum), as well as from individuals exhibiting clinical signs of the diseases, according to the procedure developed at the Department of Fish Disease of the National Veterinary Research Institute in Poland. Antimicrobial susceptibility of the tested strains was performed by the Kirby-Bauer disc diffusion method (1966) according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI, 2014), with our some modifications. Results of the antimicrobial screening revealed, that F. villosa possessed different antibacterial properties against fish pathogens. The ethanolic extract derived from leaves of F. villosa exhibited the maximum antimicrobial activity against Shewanella putrefaciens, Aeromonas sobria, and Pseudomonas fluorescens. The percentage of increase in the diameters of inhibition zones was 122.7% for Shewanella putrefaciens, 54.9% for Aeromonas sobria, and 48.5% for Pseudomonas fluorescens, respectively. F. villosa exhibited mild antibacterial properties against Serratia liquefaciens, Yersinia ruckeri, Aeromonas hydrophila, Aeromonas salmonicida subsp. salmonicida. Thus, the Shewanella putrefaciens strain exhibited the highest sensitivity to the ethanolic extract derived from leaves of F. villosa, while Serratia liquefaciens and Yersinia ruckeri strains were resistant to this extract. These findings demonstrate that plant extracts derived from plants belonging to the Ficus genus are potential sources of botanical drugs for controlling bacterial infection in aquaculture.

Requiring Reconsideration of Differences of Aeromonas Infections Between Extra-Intestinal and Intestinal in Hospitalized Patients.

The purpose of this study is to examine the variations between extra-intestinal and intestinal infections of Aeromonas in terms of strain types, risk factors, drug susceptibility results, and the distribution of drug resistance and virulence genes. A total of 188 Aeromonas strains were identified to the species level using housekeeping genes (rpoD, gyrB, and gyrA). The risk factors for Aeromonas extra-intestinal and intestinal infection, as well as mortality, were retrospectively examined in this study. The broth microdilution method was used to investigate the antimicrobial susceptibility profiles. Touchdown polymerase chain reaction (PCR) assays and DNA sequencing were employed to confirm virulence and the presence of drug resistance genes. The housekeeping genes identified 188 strains into 7 species. Extra-intestinal isolates generally contained A. caviae and A. hydrophila, while intestinal were A. veronii (p=0.0001). Extra-intestinal infections (158/188) were the main type and accounted for 24/27 of all fatalities. Malignant tumors, hepatobiliary diseases, anemia, and hypoproteinemia were linked to infections. Poor results were associated with septic shock. Using the broth microdilution method, over 80% isolates were susceptible to most antimicrobials, except for ceftazidime (79.8%) and ceftriaxone (69.7%). Except for imipenem, intestinal strains were more susceptible to other medications than extra-intestinal. Using touch-down polymerase chain reaction testing and DNA sequencing, 6 strains, 31 strains, and a strain only had bla TEM, bla CphA, and bla VIM, respectively. Two Aeromonas hydrophila each possessed bla CphA+ bla CTXM-M-9, and bla CphA + bla CTX-M-1 + bla CTX-M-15-like + bla TEM; two Aeromonas caviae each possessed bla NDM + bla CTX-M-1 +bla CTX-M-15-like + bla TEM, and bla NDM + bla TEM. Thirty-four of the 42 strains mentioned above were isolated from extra-intestinal. Act, aexT, and ascF-G, were in intestinal more frequently, but alt, hlyA, ela, and lip were in extra-intestinal more frequently. Aeromonas inside and outside intestinal differed in their clinical characteristics, drug susceptibility, drug resistance and virulence genes.

Diversidad y perfiles de resistencia a los antibióticos en especies de Aeromonas aisladas de ecosistema acuático del ecuador

Introduction: In Ecuador, the diversity of Aeromonas species and their resistance profiles to antibiotics in most aquatic ecosystems are unknown. Objective: To know the diversity of species of the genus Aeromonas and their resistance profiles to antibiotics present in the mineralmedicinal water spa “Santagua de Chachimbiro” and in the water of the Cuicocha crater volcanic lake. Methodology: Water samples from the “Santagua de Chachimbiro” spa and from the volcanic crater lake Cuicocha, located in the province of Imbabura-Ecuador, were analyzed. The isolation of the Aeromonas species was carried out by the deep seeding technique and by membrane filtration using R2A agar and ampicillin starch agar as the culture medium. The bacteria were identified following the schemes proposed by Longa et al., (1997), complemented with tests of the Microgen galleries. The antibiotic resistance profile was determined by the plate diffusion method of Kirby and Bauer (1966) interpreted according to the CLSI (2019). Results: A total of 19 strains of the genus Aeromonas belonging to 6 species were identified. Antibiotic resistance profiles show different patterns for each of the species, although species multi-resistant to antibiotics amoxicillin, amoxicillin/clavulanic acid, aztreonam, erythromycin and tetracycline prevail. Conclusions: The presence of various species of Aeromonas in aquatic environments of Ecuador with varied profiles of resistance and multi-resistance to antibiotics is demonstrated. Keywords: aeromonas; aquatic ecosystem; mineralmedicinal water; crateric lake; resistance to antibiotics

Investigation of the Antibacterial Effect of Astaxanthin and the Prevalence of Virulence and Antimicrobial Resistance Genes of Aeromonas spp.

In the study, in addition to the antibacterial effect of astaxanthin on Aeromonas hydrophila and A. sobria strains, the presence of virulence genes (Aero, act, ast, and hylA) and antibiotic resistance genes (tetC and sulI) in the strains was investigated. Antibiotic profiles of the strains were also investigated as part of the study. Strains were identified by conventional biochemical tests and PCR assay using a 16S rDNA primer pair specific for A. hydrophila. According to the results of bacteriological and molecular studies, two of the six Aeromonas strains were identified as A. hydrophila and four of them as A. sobria. The Aero virulence gene and the act virulence gene were found in all strains, while the ast and hylA virulence genes were detected only in A. hydrophila strains. All strains were resistant to chloramphenicol, tetracycline, nalidixic acid, and ampicillin in the standard disk diffusion test. Although all strains showed resistance to tetracycline and moderate resistance to oxytetracycline in the antibiogram tests, tetC antibiotic resistance gene was not detected in the strains and sulI antibiotic resistance gene was not detected in the strains. In the study, acetone solutions containing 0.1 g and 0.5 g of astaxanthin were found to have an antibacterial effect on A. hydrophila strains. Acetone solutions containing 0.1 g, 0.5 g, and 1.0 g of astaxanthin showed antibacterial effects on A. sobria strains. It was found that 0.1 g, 0.5 g, and 1.0 g astaxanthin solutions prepared with methanol and distilled water had no antibacterial effects on the strains.

The use of Levofloxacin and SUB-PRO in the treatment of bacterial haemorrhagic septicaemia in Cyprinids

The aim was to determine the effective dosages of Levofloxacin, an antibacterial drug new for aquaculture, for the treatment of bacterial haemorrhagic septicaemia in carps and improvement of the physiological state of fish following disease and antibiotic therapy.The methods: the experiments were carried out in aquaculture on juvenile carps infected with a mixed culture of pathogens: highly pathogenic strains of Aeromonas sp., Acinetobacter calcoaceticus, and Citrobacter. Three dosages of Levofloxacin were tested: 250, 500, and 1,000 mg/kg of ichtyomass with feed for 7 days. After the antibiotic therapy, a course of feeding was carried out with SUB-PRO probiotic at a dose of 0.4 g/kg of feed for 10 days.Scientific novelty: application of a broad-spectrum antibiotic Levofloxacin, an antibacterial drug new for aquaculture, in fish.The results: positive results were obtained with Levofloxacin, an antibiotic new for aquaculture, in the treatment of bacterial haemorrhagic septicaemia. The advantage of the drug is the inhibitory effect on a wide range of bacterial agents and the absence of negative effects on the physiological state of fish. An effective dosage of Levofloxacin (1,000 mg/kg of ichtyomass for 7 days) was established under experimental conditions. The positive dynamics on the blood parameters of the probiotic drug “SUB-PRO” after the disease and antibiotic therapy was revealed, which provided an increase in the resistance of the fish organism.The practical significance: the findings will be crucial in the development of practical recommendations for the treatment of bacterial haemorrhagic septicaemia of fish in aquaculture.

Co-Prevalence of Virulence and Pathogenic Potential in Multiple Antibiotic Resistant Aeromonas spp. from Diseased Fishes with In Silico Insight on the Virulent Protein Network.

Aeromonas species exhibit widespread presence in food, poultry, and aquaculture. They are major multi-drug-resistant fish pathogens. This study aims to identify Aeromonas species harbouring virulence genes aerolysin, flagellin, and lipase from diseased fishes of Assam wetlands with association with antibiotic resistance and in vivo pathogenicity. One hundred and thirty-four Aeromonas strains were isolated and thirty representative species identified using genus-specific 16S rRNA gene amplification. A. veronii was most prevalent (53.7%) followed by A. hydrophila (40.2%), A. caviae (4.47%), and A. dhakensis (1.49%). Ninety percent (90%) of strains harboured at least one of the studied virulence genes: aerA (73.3%), lip (46.6%), and flaA (26.6%). The highest multiple antibiotic resistance (MAR) index 0.8 corresponded to A. hydrophila DBTNE1 (MZ723069), containing all the studied genes. The lowest LD50 values (1.6 × 106 CFU/fish) corresponded to isolates having both aerA and lip. β-lactams showed utmost resistance and lowest for aminoglycosides. There was a significant (p < 0.05) Pearson chi-square test of association between the occurrence of virulence and antibiotic resistance. The in silico protein−protein interaction revealed important drug targets, such as σ28 transcription factor, aminoacyl-tRNA synthetase, and diacylglycerol kinase, with significant (p < 0.05) enrichment. This study suggests that fish-isolate Aeromonas strains represent potential threat to aquaculture with subsequent risk of transferring antibiotic resistance to human pathogens.

The effect of food processing factors on the growth kinetics of Aeromonas strains isolated from ready-to-eat seafood

Aeromonas are ubiquitous aquatic bacteria and frequently isolated from seafood. There is growing awareness of Aeromonas as foodborne pathogens, particularly in connection with consumption of ready-to-eat (RTE) seafood. The aim of this study was to investigate the effect of food processing factors on the growth kinetics of eight Aeromonas strains (representing seven species) isolated from RTE seafood. The effect of low temperature (4 and 8 °C) in combination with different NaCl concentrations (0.5–6.5 %) or with two purified condensate smokes (PCSs; Red Arrow SmokEz VTABB and JJT01) at different concentrations (0–0.26 %) was studied in Trypton Soy Broth (TSB). In food processing, application of PCS is considered healthier than traditional smoking. Growth kinetics parameters of each strain were estimated by using a primary predictive model. Our result showed that the addition of 3.5 % NaCl at refrigeration temperature (4 °C) was not sufficient to inhibit the growth of A. media, A. bestiarum, A. piscicola, and A. salmonicida, while higher NaCl concentration (≥5.0 %) at 8 °C suppressed their growth. On the other hand, our result demonstrated the antimicrobial potential of using PCS at maximal allowed concentration (0.26 %) against Aeromonas. PCS concentration and phenol content were important factors influencing the growth kinetics parameters of Aeromonas. Moreover, the growth kinetics of three Aeromonas strains were further studied in commercially produced vacuum-packed fresh and cold-smoked salmon stored at 4 °C for 14 and 21 days, respectively. Our results demonstrate that vacuum packing combined with cold storage at 4 °C was insufficient to inhibit the growth of Aeromonas in fresh salmon, while the growth was inhibited in a minimally salted cold-smoked salmon (salt content of 1.8 %). Our study implies that mild food processing factors applied in the production of RTE seafood might not guarantee the total inhibition of Aeromonas. Even though further studies on evaluating the antimicrobial potential of PCSs in actual seafood matrixes are necessary, the present study suggests that PCS technology might be a promising approach to prevent the potential growth of Aeromonas.

Enhanced Hemolytic Activity of Mesophilic Aeromonas salmonicida SRW-OG1 Is Brought about by Elevated Temperatures.

Aeromonas salmonicida is a well-known cold-water pathogenic bacterium. Previously, we reported the first isolation of pathogenic A. salmonicida from diseased Epinephelus coioides, a kind of warm-water fish, and it was proved to be a putative mesophilic strain with potent pathogenicity to humans. In order to investigate the mechanisms underlying mesophilic growth ability and virulence, the transcriptome of A. salmonicida SRW-OG1 at 18, 28, and 37 °C was analyzed. The transcriptome of A. salmonicida SRW-OG1 at different temperatures showed a clear separation boundary, which might provide valuable information for the temperature adaptation and virulence regulation of A. salmonicida SRW-OG1. Interestingly, aerA and hlyA, the hemolytic genes encoding aerolysin and hemolysin, were found to be significantly up-regulated at 28 and 37 °C. Since aerolysin and hemolysin are the most well-known and -characterized virulence factors of pathogenic Aeromonas strains, the induction of aerA and hlyA was associated with the mesophilic virulence. Further study proved that the extracellular products (ECPs) purchased from A. salmonicida SRW-OG1 cultured at 28 and 37 °C showed elevated hemolytic activity and virulence than those at 18 °C. Moreover, the silence of aerA and hlyA led to significantly decreased hemolysis and virulence. Taken together, our results revealed that the mesophilic virulence of A. salmonicida SRW-OG1 might be due to the enhanced expression of aerA and hlyA induced by elevated temperatures.

Genetic Diversity, Antibiotic Resistance, and Pathogenicity of Aeromonas Species from Food Products in Shanghai, China

ObjectiveAeromonas has recently been recognized as an emerging human pathogen. Aeromonas-associated diarrhea is a phenomenon occurring worldwide. This study was designed to determine the prevalence, genetic diversity, antibiotic resistance, and pathogenicity of Aeromonas strains isolated from food products in Shanghai. MethodsAeromonas isolates (n = 79) collected from food samples were analyzed using concatenated gyrB-cpn60 sequencing. The antibiotic resistance of these isolates was determined using antimicrobial susceptibility testing. Pathogenicity was assessed using β-hemolytic, extracellular protease, virulence gene detection, C. elegans liquid toxicity (LT), and cytotoxicity assays. ResultsEight different species were identified among the 79 isolates. The most prevalent Aeromonas species were A. veronii [62 (78.5%)], A. caviae [6 (7.6%)], A. dhakensis [3 (3.8%)], and A. salmonicida [3 (3.8%)]. The Aeromonas isolates were divided into 73 sequence types (STs), of which 65 were novel. The isolates were hemolytic (45.6%) and protease-positive (81.0%). The most prevalent virulence genes were act (73.4%), fla (69.6%), aexT (36.7%), and ascV (30.4%). The results of C. elegans LT and cytotoxicity assays revealed that A. dhakensis and A. hydrophila were more virulent than A. veronii, A. caviae, and A. bivalvium. Antibiotic resistance genes [tetE, blaTEM, tetA, qnrS, aac(6)-Ib, mcr-1, and mcr-3] were detected in the isolates. The multidrug-resistance rate of the Aeromonas isolates was 11.4%, and 93.7% of the Aeromonas isolates were resistant to cefazolin. ConclusionThe taxonomy, antibiotic resistance, and pathogenicity of different Aeromonas species varied. The Aeromonas isolates A. dhakensis and A. hydrophila were highly pathogenic, indicating that food-derived Aeromonas isolates are potential risks for public health and food safety. The monitoring of food quality and safety will result in better prevention and treatment strategies to control diarrhea illnesses in China.

Validation of the AquaCHROM™ ECC for the Detection and Enumeration of Coliforms and Escherichia coli in Water Samples: AOAC Performance Tested MethodSM 072202.

The AquaCHROM™ ECC method from CHROMagar is intended for the detection and enumeration of Escherichia coli and coliform bacteria in 100 mL water samples after 18-24 h of incubation at 35-37°C. To validate the AquaCHROM ECC method for qualitative and quantitative detection of E. coli and coliforms with different water matrixes. Inclusivity/exclusivity studies were conducted. AquaCHROM ECC was compared to U.S. cultural reference methods in unpaired matrix studies for detection of E. coli and coliforms in tap water, well water, lake water, and bottled water, and for enumeration in tap water, well water, and lake water. Three production lots of AquaCHROM ECC were tested for product consistency and stability. Variations in incubation time and temperature were evaluated in robustness testing. Inclusivity/exclusivity results demonstrated expected performance with the exception of three strains of Salmonella enterica, two species of Shigella, and one strain of Aeromonas, which turned the media blue or yellow. Results from the matrix studies demonstrated that AquaCHROM ECC and the reference methods are not statistically different for detection of E. coli and coliforms and statistically equivalent for enumeration of E. coli and coliforms. The AquaCHROM ECC powder production was proven to be consistent with a 24-month shelf life. Variation in temperature did not affect the method performance. Shortening the incubation time is not recommended. AquaCHROM ECC is an effective method for the detection and enumeration of E. coli and coliforms for the water matrixes evaluated. The AquaCHROM ECC method is a quick, one-step method for the recovery and enumeration of E. coli and coliforms in 100 mL water samples. It is a non-agar-based chromogenic medium which provides a clear result without the use of a UV lamp.

Characterization and valorization of a biosurfactant produced by Aeromonas salmonicida isolated from the marchika lagoon of Nador

Biosurfactants are surface-active molecules produced by various microorganisms, such as bacteria, which allow them to exhibit a variety of biological functions. The production of these secondary metabolites requires the use of substrates such as glycerol or hydrocarbons. The objective of this study is the valorization of biomolecules extracted from a bacterial strain Aeromonas salminicida isolated from the lagoon of Marchika in Nador. The production of biosurfactants was identified by screening with standard methods. The crude product was characterized by TLC, IFTIR and GC-MS. Antibacterial activity was evaluated and antioxidant activity assessment was carried out by using in vitro DPPH scavenging capacity and reducing power test. Biosurfactant screening tests revealed a reduction in surface tension and a change in emulsification index of 57%, preliminary characterization indicates that it was probably a lipopeptide biosurfactant. It has been shown that they are capable of exhibiting antimicrobial activity as well as an antioxidant effect.

Aeromonas allosaccharophila Strain AE59-TE2 Is Highly Antagonistic towards Multidrug-Resistant Human Pathogens, What Does Its Genome Tell Us?

Multidrug-resistant bacteria are of critical importance and a problem for human health and food preservation; the discovery of new antimicrobial substances to control their proliferation is part of the solution. This work reports on 57 antagonistic Aeromonas strains, of which 38 strains were antagonistic towards problematic human pathogens. The genome of the most antagonistic strain was sequenced and identified as Aeromonas allosaccharophila. Its genome was fully annotated and mined for genes that might explain that activity. Strain AE59-TE was antagonistic toward clinically relevant gram-negative and gram-positive multidrug-resistant bacteria, including Klebsiella pneumoniae KPC, Escherichia coli ESBL, Salmonella typhimurium, and Staphylococcus aureus MRSA. Strain AE59-TE2 was identified by multilocus sequence analysis. Genome mining identified four genes homologous to the bacteriocin, zoocin A from Streptococcus equi and a gene 98% similar to cvpA linked to colicin V production. A. allosaccharophila strain AE59-TE2 produced antimicrobial activity against a broad range of bacteria, including important gram-negative bacteria, not typically targeted by bacteriocins. Herewere described novel zoocin genes that are promising for industrial applications in the food and health sectors. Interesting and important antagonistic activity is described combined with the first detailed genomic analysis of the species Aeromonas allosaccharophila.

In vitro assay of Lippia graveolens and Lippia alba extracts against Aeromonas spp isolated from tilapia (Oreochromis niloticus)

This study evaluated the antimicrobial activity of Lippia graveolens and Lippia alba extracts and essential oils against nine strains of Aeromonas spp., isolated from Oreochromis niloticus. The crude extracts were obtained by percolation technique and CO2 supercritical fluid extraction, while the essential oils by applying hydro-distillation technique using a Clevenger apparatus. The antimicrobial activity for each extract and essential oils was verified through the disc diffusion method at 24 hours. The essential oil of L. graveolens showed higher effectiveness to inhibit fish bacterial pathogens (100%) than the extracts, revealing an inhibition zone diameter that ranged from 25.20 - 36.94 mm. The extracts from supercritical fluid and from the percolation technique with ethyl acetate and cyclohexane presented the same effectiveness (77.78%). The crude extract obtained with ethanol 95% showed limited antimicrobial effect (22.22%), presenting the smallest inhibition zone (ranged from 8.34 to 9.57 mm). On the other hand, L. alba displayed a lower antibacterial activity, being the essential oil 66.67% effective, presenting an inhibition zone ranging between 10.68 to 16.29 mm. The result of this study indicates that essential oils from both L. graveolens and L. alba offer a promising alternative for the control of Aeromonas spp. growth.

Generalised infection evoked by Aeromonas hydrophilia in a patient with unclassified arthritis

Generalised infection evoked by the bacterium of Aeromonas hydrophilia in a 69-year-old patient with unclassified arthritis, hospitalised due to an exacerbation of rheumatic disease at the Rheumatology Ward, in September 2019. From the very beginning of the disease, the patient was chronically treated with steroids, for the next few years with chloroquine and a brief moment with methotrexate (MTX) which had to be discontinued due to the patient’s gastrointestinal intolerance. The bacterium of Aeromonas hydrophilia is commonly known as an etiological factor of fish diseases (e.g. salmonid ulcers or carp erythrodermatitis). Hitherto only Aeromonas hydrophilia, Aeromonas Caviae and Aeromonas Sobria have been the Aeromonas strains known to threaten human health. Aeromonas hydrophilia causes opportunistic infection in individuals with a disturbed immune system. In the literature, one can find described and analysed the cases of skin and soft tissue infections, in tropical and subtropical countries in particular.

Prospecting of essential oils in combination with florfenicol against motile Aeromonas isolated from tambaqui (Colossoma macropomum).

Natural products with antimicrobial activity and their association with synthetic antimicrobials are a sustainable option in fish farming. The objective of this study was to determine antimicrobial activity, antibiofilm potential and synergism of five essential oils (EOs) with florfenicol against motile Aeromonas isolated from Amazonian Colossoma macropomum. As their major constituent, the EOs of the species of Aloysia triphylla, Croton cajucara (red and white morphotype), Cymbopongo citratus and Lippia gracilis present β-pinene (22.1%), germacrene D (11.5%), linalool (23%), geranial (45.7%) and carvacrol (42.2%), respectively. The EOs of L. gracilis and C. citratus showed the best antimicrobial activities against the Aeromonas strains (5mgmL-1). All EOs interfered with biofilm formation and consolidated biofilm. The EOs of A. triphylla, C. citratus and L. gracilis showed a synergistic effect with florfenicol, reducing the amount of the chemical into the water systems while treatment.

Isolation and characterization of a norfloxacin-degrading bacterial strain Aeromonas hydrophila sp. N215-1

Norfloxacin, a third-generation fluoroquinolone antibiotic, is increasingly used in the treatment of human and animal diseases, and being frequently detected in the environment. Norfloxacin has a broad spectrum of antibacterial activity, so few bacteria can degrade norfloxacin effectively. This is the first report on norfloxacin biodegradation by Aeromonas hydrophila sp. N215-1. Response surface methodology was employed to optimize the bacterial growth and degradation of norfloxacin of strain N215-1 in flask scale. The maximum yield of 0.31 in OD60f0 and 25.0% in degradation efficiency in 24 h were obtained when using RSM optimized medium, which improved strain growth and degradation by 3.88 and 5.68-fold, respectively. The kinetic analysis indicated that strain N215-1 could grow with the maximum specific growth rate, inhibit constant (Ki) and semi-saturation (Ks) constant of 0.2640/h, 23.9909 mg/L and 1.9817 mg/L, respectively. Furthermore, the optimized medium was applied in an 85 L modified AAO reactor with 2% N215-1 bioaugmentation, an increased norfloxacin removal rate from 56.0% to 81.2% was achieved. This study highlights a significant potential of using microbial co-metabolic culture for microbial remedied of norfloxacin-contaminated environments.

A high level of antibiotic resistance in Klebsiella and Aeromonas isolates from street water sold in Mozambique, associated with the prevalence of extended-spectrum and AmpC ß-lactamases

This study aims to evaluate the resistance profile and the prevalence of antibiotic resistance genes in 30 isolates of Klebsiella spp. and Aeromonas spp. recovered from water sold in the streets of Maputo. Susceptibility profiles to 15 antibiotics were performed according to Clinical Laboratory Standard Institute guidelines with antibiotic disks on Mueller-Hinton agar plates. Multiplex PCRs were performed targeting 10 ß-lactamase genes, five ESBL (blaTEM-variants, blaOXA-variants, BlaSHV-variants, MCTX-M Group 1 and Group 9 variants) and five AmpC (ACC variants, FOX variants, MOX variants, CIT variants and DHA variants). The results showed a high prevalence of Klebsiella resistance to ß-lactam antibiotics, such as amoxicillin/clavulanic acid (62.5%), amoxicillin (56.3%), ampicillin (50%), cefoxitin (43.8%), and cefotaxime (43.8%). Aeromonas showed resistance to cefoxitin and ampicillin (71.4%), amoxicillin/clavulanic acid (57.1%) and imipenem (42.9%). ESBL blaOXA -variants, blaSVH -variants, MCTX-M Group 1 variants, and MCTX-M Group 9 variants were the most prevalent b-lactam genes, followed by the b-lactams AmpC, ACC variants and FOX variants. It is extremely important to improve waterborne disease control strategies, especially in terms of public awareness of the potential health implications of multidrug-resistant strains of Klebsiella and Aeromonas, which are often neglected.