Aeromonas Infection Research Articles

P689 Aeromonas infection and Inflammatory Bowel Disease: a single tertiary center analysis

Abstract Background Aeromonas genus consists of gram-negative rods known to cause a spectrum of diseases in humans. Inflammatory bowel disease (IBD) is an idiopathic complex condition where multiple factors contribute to its development and progression. The association of Aeromonas infection with IBD manifestation have been proposed by other authors and is still largely unknown. We aim to look for the significance of Aeromonas infection and for significant differences between IBD and non-IBD patients. Methods A retrospective observational data retrieval and analysis was performed of all patients positive for Aeromonas in stool cultures, during a 10-year period, from a Portuguese tertiary and university setting hospital. Results Fifty patients, 56% of male sex and with a mean age of 42.1 years-old were included. Thirty-eight (76%) were non-IBD and 12 (24%) were IBD patients. IBD patients were more frequently under immunosuppressors. Two patients were asymptomatic and 44% develop mild, 44% moderate and 16.7% severe infection. The main Aeromonas strains isolated were Aeromonas hydrophila/caviae. Co-isolation with other bacteria was found in 4 non-IBD patients and histological findings compatible with Cytomegalovirus were found in 2 IBD patients. Non-IBD patients presented more frequently with fever and IBD patients with bloody diarrhea and abdominal pain. There was higher tendency for severe infection rate in IBD patients with higher antimicrobial therapy use. Steroids were exclusively used in IBD group. No significant differences were observed for isolation of Aeromonas resistant strains. From the IBD, 4 patients had the diagnosis of Ulcerative Colitis and 9 of Crohn’s Disease with colonic involvement. Of them 5 patients received the diagnosis after the acute episode of Aeromonas infection. Conclusion Clinical presentation of Aeromonas infection differ between IBD and non-IBD patients. Non-IBD patients had milder severity of infection with less use of antibiotics. Aeromonas infection seem to play an important role on the contribution of IBD manifestation.

Molecular phylogeny, structure modeling and in silico screening of putative inhibitors of aerolysin of Aeromonas hydrophila EUS112

Aeromonas hydrophila, a Gram-negative bacterium, causes diseases in fish, resulting in excessive loss to the aquaculture industry. Aeromonas is a highly heterogeneous group of bacteria, and the heterogeneity of the genus is attributed to variation and diversity in the virulence factors and toxins among various Aeromonas strains. One of the major toxins aerolysin, secreted by the bacterium, causes hemorrhagic-septicemia and diarrhea and can serve as a drug target. Here, we describe characterization, molecular phylogeny, and homology modeling of the aerolysin of A. hydrophila strain EUS112 (AhEUS112 ) cloned in our lab. The encoded aerolysin is 485 amino acids long with an N-terminal signal sequence of 23 amino acids. Phylogenetic analysis of the aerolysin of AhEUS112 revealed that it belongs to a diverse group of toxins, showing maximum similarity with aerolysins of other Aeromonas strains followed by Vibrio toxin. The homology model of the mature aerolysin of AhEUS112 was generated using the crystal structure of a mutant aerolysin (PDB#3g4n) as the template, which showed that the encoded aerolysin exists as a channel protein. Validation of the generated model using bioinformatics tool confirmed it to be a good quality model that can be used for drug design. Molecular dock analysis revealed that drugs, aralia-saponin I, cyclamin, ardisiacrispin B, and aralia-saponin II bind to aerolysin with a higher affinity as compared to other drugs and at functionally important amino acids of aerolysin. Hence, these molecules can act as an effective therapeutics for inhibiting the aerolysin pore formation and curtail the severity of Aeromonas infection. Communicated by Ramaswamy H. Sarma

Construction and immune efficacy of recombinant Lactobacillus casei expressing OmpAI of Aeromonas veronii C5–I as molecular adjuvant

Despite advancements in diagnosis and control, Aeromonas infections are considered the leading cause of economic aquaculture loss. In this study, to enhance DNA vaccine efficacy against Aeromonas infections, a fused DNA fragment (1504 bp) of the OmpAI gene from Aeromonas veronii (A. veronii) combined with the C5–I gene from the common carp was generated with splicing by overlapping PCR (SOE-PCR) and expressed in Lactobacillus casei strain CC16. Protein C5–I served as a molecular adjuvant for the antigen OmpAI. Two types of fusion antigens were developed (anchored and secretory). Generally, anchored-type antigens are more effective in inducing immune responses in fish than secretory antigens. Western blot analysis showed that the bands of both antigens were present at 58 kDa. After oral immunization, both DNA vaccines enhanced the serum levels of AKP, ACP, SOD and LZM in immunized carp; the genes IL-10, IL-1β, TNF-α, and IFN-γ in the heart, liver, spleen, head kidney, and intestinal tract were upregulated; and a stronger phagocytic response was triggered in immunized fish. In addition, common carp administered the fused antigens were more protected from Aeromonas challenge (60–73.3% protection). Recombinant Lactobacillus bacteria expressing the fused protein showed a greater propensity for colonization in the intestinal tract in immunized fish than in controls. Here, we provide a promising approach to improve DNA vaccine immunogenicity for protecting common carp from A. veronii infections.

Immuno-protective efficiency of feed-based whole-cell inactivated bivalent vaccine against Streptococcus and Aeromonas infections in red hybrid tilapia (Oreochromis niloticus × Oreochromis mossambicus)

Streptococcosis and motile aeromonad septicemia (MAS) are well-known diseases in tilapia culture, which cause mass mortality with significant economic losses. The development of feed-based bivalent vaccines in controlling these diseases has been initiated, however, the mechanisms of immunities and cross-protection in fish remain unclear. This study was conducted to assess the immuno-protective as well as the cross-protective efficacy of a newly developed feed-based bivalent vaccine against Streptococcus and Aeromonas infections in red hybrid tilapia. A total of five groups of fish were vaccinated orally through two different techniques; bivalent vaccine (inactivated Streptococcus iniae and Aeromonas hydrophila) sprayed on feed pellets (BS group); bivalent vaccine (inactivated S. iniae and A. hydrophila) incorporated in feed (BI group); monovalent inactivated S. iniae and A. hydrophila vaccine separately incorporated into feed as monovalent S. iniae (MS group) and monovalent A. hydrophila (MA group); and control group (without vaccine). The feed-based vaccine was delivered orally at 5% of body weight for five consecutive days. The booster doses were given in the same manner on weeks 2 and 6. Serum and skin mucus samples were collected to assess the IgM responses using indirect ELISA. The first administration of the feed-based vaccine stimulated the IgM levels that lasted until week 3, while the second booster ensured that the IgM levels remained high for a period of 16 weeks in the BI, MS and MA groups. The BI group developed a strong and significantly (P < 0.05) higher systemic and mucosal IgM responses against both S. iniae and A. hydrophila and also cross-protective antigen S. agalactiae and A. veronii compared to the BS and control groups. Quantitative real-time PCR results also showed that the relative expressions of IL-8, INF-γ and IgM in the BI immunized fish spleen, head kidney and hindgut exhibited various significant (P < 0.05) rising trends following both the vaccination and the challenge phase. On weeks 10, all fish were challenged through the intraperitoneal route, where relative percent survivals (RPS) of 82.22 ± 3.85% when challenged with S. iniae, 77.78 ± 3.85% when challenged with A. hydrophila and 77.78 ± 3.85% when co-challenged with both S. iniae and A. hydrophila were observed in the BI group, which were significantly higher (P < 0.05) compared to the other groups. The BI group also showed significantly (P < 0.05) higher partial cross-protections following challenges with S. agalactiae (RPS at 60.00 ± 6.67%) and A. veronii (RPS at 57.78 ± 7.70%). This study demonstrated that immunization with feed-based BI vaccine elicited immune responses that were capable of protecting red hybrid tilapia against streptococcosis and MAS.

Comparison of species, virulence genes and clones of Aeromonas isolates from clinical specimens and well water in Okinawa Prefecture, Japan.

To reveal the sources of Aeromonas infection in Okinawa Prefecture of Japan, the species, virulence genes and clones of strains isolated from clinical specimens and well water were compared. The properties of both isolates were investigated by sequencing of rpoD, detection of 10 virulence genes using PCR and genotyping with pulsed-field gel electrophoresis. In all, 68 clinical and 146 well water strains of Aeromonas were isolated and the main species were A. caviae, A. dhakensis, A. hydrophila and A. veronii biovar sobria. Aeromonas dhakensis possessed various virulence genes; however, A. caviae possessed only fla. The same or similar clones were distributed in certain areas of Okinawa and one clone had survived several months in the biliary system of two patients, respectively. Although the same Aeromonas clone was not isolated from clinical and well water samples, our study revealed the detected patterns of virulence genes in both isolates, the distribution of identical/similar clones in the Okinawan environment and long-time survival in patient's organs. We investigated the association between Aeromonas patients and well water exposure. This study provides the properties of species, virulence genes and clones of Aeromonas isolated from samples of these origins.

Taxonomy, virulence determinants and antimicrobial susceptibility of Aeromonas spp. isolated from bacteremia in southeastern China

BackgroundThe study aimed to elucidate the species taxonomy, clinical manifestations, virulence gene profiles and antimicrobial susceptibilities of Aeromonas strains isolated from life-threatening bacteremia in southeastern China.MethodsClinical samples of Aeromonas causing bacteremia were isolated from a teaching hospital in Wenzhou from 2013 to 2018 and a retrospective cohort study was performed. Aeromonas strains were identified at species level by housekeeping gene gyrB. Virulence and drug resistance-associated genes were screened by polymerase chain reaction (PCR) and antimicrobial susceptibility testing (AST) was performed by the VITEK 2 Compact system.ResultsA total of 58 Aeromonas isolated from patients with bacteremia were collected during 6 years (2013–2018). 58 isolates were identified to five different species, where Aeromonas dhakensis appeared to be the predominant species (26/58), followed by Aeromonas veronii (13/58), Aeromonas caviae (10/58), Aeromonas hydrophila (7/58) and Aeromonas jandaei (2/58). 16 of 58 patients had poor prognosis. Poor prognosis was significantly associated with liver cirrhosis and inappropriate empirical antimicrobials therapy. The progression of bacteremia caused by Aeromonas was extremely fast, especially in A. dhakensis infections. Virulence genes aer, lip, hlyA, alt, ast, and act, were detected at ratios of 24.1% (14/58), 62.1% (36/58), 65.5% (38/58), 58.6% (34/58), 15.5% (9/58) and 65.5% (38/58), respectively. Antimicrobial susceptibility testing exhibited that 9 out of 58 isolates were identified as multi-drug resistant (MDR) organism. The blaTEM gene was identified in all 9 MDR isolates. blaSHV, blaAQU-1, blaMOX, blaCepH, blaCphA and aac(6′)-Ib-cr were detected in 4 isolates, 2 isolates, 1 isolate, 3 isolates, 8 isolates, and 3 isolates, respectively. The majority of Aeromonas strains maintained susceptible to 3rd generation cephalosporins, aminoglycosides, fluoroquinolones and furantoin.ConclusionsThe prevalence and dangerousness of Aeromonas infections, especially A. dhakensis, are underestimated in clinic. Continuous monitoring is essential to keep track of MDR Aeromonas due to the increasing prevalence recently and a more effective measure is required to control the spread of resistance determinants.

Implementation of a Leeches + Antimicrobial Prophylaxis Order Panel to Optimize Medicinal Leech Use at a Tertiary Care Academic Medical Center

Medicinal leech therapy promotes vascular flow and can be used to salvage grafts. Medicinal leeches have a symbiotic relationship with Aeromonas species and can therefore present a risk of bacterial transmission to patients. Antimicrobial prophylaxis is warranted for the duration of leech therapy, however, an institutional evaluation of 40 patients receiving medicinal leech therapy demonstrated poor adherence with recommendations. An electronic medical record order panel for antimicrobial prophylaxis with medicinal leech therapy was implemented, leading to a subsequent improvement in adherence to prophylaxis use, including significant increases in the ordering of antibiotics and the appropriate timing of initiation in the subsequent 10 patients receiving medicinal leech therapy after panel implementation. Aeromonas infections were rare before and after panel implementation, and developed only in the patient subset with non-optimized prophylaxis.

Recombinant outer membrane protein OmpC induces protective immunity against Aeromonashydrophila infection in Labeorohita

Aeromonashydrophila is an opportunistic pathogen that causes enormous loss to aquaculture industry. The outer membrane proteins of Aeromonas help in bacterium-host interaction, and are considered to be potential vaccine candidates. In the present study, we evaluated immunogenicity and protective efficacy of recombinant OmpC (rOmpC) of A. hydrophila in Indian major carp, Labeorohita. The rOmpC-vaccinated fish produced specific anti-rOmpC antibodies with a significant antibody titer, and the antisera could specifically detect the rOmpC in the cell lysates of Escherichia coli expressing rOmpC and cross-react with different Aeromonas lysates, indicating the suitability of the anti-rOmpC antisera to detect Aeromonas infection. A significant increase was noted in ceruloplasmin level, myeloperoxidase and anti-protease activities in transient and temporal manner the sera of the rOmpC-immunized fish as compared to PBS-control fish. Higher agglutination- and hemolytic activity titers in the anti-rOmpC antisera indicate stimulation of innate immunity. Expression of immune-related genes comprising various acute phase proteins, cytokines and inflammatory response molecules were modulated in the head kidney of rOmpC-immunized L. rohita. While IgM, IL1β, and TLR-22 were significantly up-regulated at early time points (3 h–72 h), the others showed a transient augmentation at both early and later time points (SOD, lysozymes C and G, NKEF-B, C3, CXCa and TNF-α) in the rOmpC-immunized L. rohita in comparison to PBS-injected controls. These data suggest that the rOmpC-induced immune response is temporally regulated to confer immunity. In vivo challenge of the rOmpC-immunized fish with A. hydrophila showed significantly greater survival when compared to PBS-injected control fish. Thus, our results highlight the immunomodulatory role of rOmpC and demonstrate its protective efficacy in L. rohita, along with the use of anti-rOmpC antisera in detecting Aeromonas infections.

Ornamental fish: a potential source of pathogenic and multidrug-resistant motile Aeromonas spp.

Aeromonas spp. are ubiquitous bacteria that cause diseases in fish and other aquatic animals. They are the natural inhabitants of different aquatic environments, such as freshwater, brackishwater and marinewater. Extrinsic stressors, such as crowding, unhygienic handling, poor water quality, polluted feeding and inadequate nutrition, can predispose fish to Aeromonas infection. In ornamental fish, motile Aeromonas spp. are known as aetiological agents of motile aeromonad infections, which cause significant mortality in fish and economic loss in the ornamental fish industry. The existence of different virulence factors leads to the virulence potential of motile Aeromonas spp. There are several antimicrobials used to treat bacterial infections in ornamental fish. However, the extensive use of antimicrobials in the ornamental fish industry causes multidrug resistance. This article reviewed a multitude of virulence factors that are related to the ornamental fish-borne Aeromonas pathogenicity and the antimicrobial resistance determinants related to the multidrug resistance phenotypes of motile Aeromonas spp. in ornamental fish.

Gastrointestinal infection with Aeromonas: incidence and relationship to inflammatory bowel disease

Abstract Introduction Aeromonas can cause several diseases in humans, with gastroenteritis accounting for most cases. The role of Aeromonas as a pathogen in human enterocolitis has been questioned in recent years. Objectives To determine the incidence of gastrointestinal infection caused by Aeromonas in our area and its possible relationship to inflammatory bowel disease. Patients and methods This was a retrospective observational study. All adult patients with a positive stool culture for Aeromonas were identified between January 2015 and December 2017 at Hospital Galdakao-Usansolo (Vizcaya, Spain). Results Ninety-eight patients were identified (median age 62 years; 51% women). Therefore, the incidence in our area was 32 cases per 105 inhabitants per year. Eleven per cent of them had been previously diagnosed with inflammatory bowel disease (four with ulcerative colitis and seven with Crohn's disease). Patients with inflammatory bowel disease more often received immunosuppressive therapy. Conversely, patients without inflammatory bowel disease suffered from more comorbidities. We also found comorbidity to be the risk factor most associated with Aeromonas infection. Conclusion Aeromonas infection is a common gastrointestinal infection that may occur in both immunocompetent and immunocompromised patients. Immunosuppression is a significant factor in inflammatory bowel disease patients, while comorbidity seems to confer a higher risk on patients without this disease.

Immunomodulatory and Antimicrobial potential of ethanolic extract of Himalayan Myrica esculanta in Oncorhynchus mykiss: Molecular modelling with Aeromonas hydrophila functional proteins

The present study was carried out to investigate the antimicrobial and immunomodulatory activity of Myrica esculenta ethanolic leaf extract (MeALE) in rainbow trout. The juvenile fish were immersed in 20 mg/l (T1) and 40 mg/l (T2) MeALE for 2 and 6 h and then challenged with pathogenic bacteria, A. hydrophila (ATCC 7966, USA) after 6 h post immersion in MeALE. The immuno-haematological parameters and relative percentage survival were recorded over 7 days post-exposure. The amino acid interaction of functional proteins of bacteria with myricetin, the active ingredient of M. esculenta was performed by AutoDock Vina software. FTIR detected the characteristic peak values and revealed the presence of various functional groups, viz. alkenes, amines, alcohols, phenols and aromatic compounds. The MIC of MeALE was found to be 2 mg/ml while MBC was recorded to be 25 mg/ml. Molecular docking revealed a strong affinity between myricetin and functional proteins of the pathogen. The fish immersed in 40 mg/l MeALE showed a significant increase in haematological indices and non-specific immunological parameters. The current study reports the successful use of MeALE as an antimicrobial and immunostimulatory agent in rainbow trout and recommends the dosage of 40 mg/l MeALE for preventing Aeromonas infection.

Multidrug resistant Aeromonas infection following medical leech therapy: A case report and development of a joint antimicrobial stewardship and infection prevention protocol

ObjectiveAeromonas sp. infections are a recognized complication of medical leech therapy (MLT). In patients requiring MLT, ciprofloxacin or trimethoprim–sulphamethoxazole are commonly used to prevent such nosocomial infections. After a patient at our institution developed a MLT-associated multi-drug resistant (MDR) Aeromonas infection, we developed and evaluated a joint antimicrobial stewardship and infection prevention protocol for MLT at our institution. MethodsWe describe a case of a surgical site infection with MDR Aeromonas following MLT that was resistant to typically prescribed prophylactic antimicrobials, and development of a new leech culture protocol to proactively monitor for antimicrobial resistance among our institution’s leech supply. We also report the rates of MLT-associated infections prior to and following implementation of this protocol and the antimicrobial susceptibility profiles detected in leech culture at our institution. ResultsBetween October 2014 and February 2018, 46 patients received MLT at our institution. Other than the case described in this report, no other instances of MLT-related infections were noted during this time period. Culture results from 22 leeches in six batches since February 2018 showed that all were susceptible to ciprofloxacin, TMP-SMX, and ceftriaxone. Since initiation of a leech culture protocol, no further cases of MLT-associated infections have been reported at our institution. ConclusionsIn light of increasing antimicrobial resistance and the potentially devastating consequences of MLT-associated infections, institutions offering MLT should be aware of these risks and ensure that protocols are in place to minimize infection risks for patients.

S1793 Aeromonas Spp. Enteritis in the Course of Recurrent Immune Checkpoint Inhibitor Colitis

INTRODUCTION: The role of Aeromonas spp. as a gastrointestinal pathogen is debated.1 Here we present an Aeromonas infection in a patient with recurrent immune checkpoint inhibitor (ICI) colitis. CASE DESCRIPTION/METHODS: A 61-year-old Caucasian female with Stage IV Melanoma and history of recurrent ICI colitis presented with 6 days of watery diarrhea, nausea and vomiting. The patient had recently completed 2nd induction of Ipilimumab, an anti-CTLA-4 immunotherapy agent, while being on vedolizumab concurrently with oral budesonide for previous episodes of nausea and vomiting. She endorsed intermittent abdominal cramping and decreased PO tolerance but denied fevers, bloody diarrhea, hematemesis. On exam, abdomen was benign and non-tender. Serology labs were unremarkable. Stool studies were significant for positive lactoferrin and elevated calprotectin to 432 μg/g. Patient was started on solumedrol 40 mg IV BID empirically. GI multiplex PCR panel was negative including C. Difficile. Stool culture was positive for pan-susceptible Aeromonas spp. Patient was started on a 7-day course of Ciprofloxacin 500 mg BID and prednisone taper resulting in improved PO tolerance, resolution of diarrhea and decreased nausea and vomiting on discharge. DISCUSSION: Aeromonas spp. infections, although rare, most typically present with gastrointestinal symptoms. It has been implicated as an opportunistic pathogen in inflammatory bowel disease; however, its role in patients with ICI colitis remains unclear.2 Our patient had presented with similar symptoms and negative stool cultures several months prior and was treated for ICI colitis. This diagnosis was confirmed by colonoscopy showing active cryptitis and apoptotic bodies. In the current presentation, it is unclear what the primary cause of her symptoms was. Concurrent administration of both antibiotics and steroids improved her symptoms possibly suggesting a combination of Aeromonas spp. infection and ICI colitis which has never been reported previously in literature. Further studies with larger cohorts of patients with ICI colitis are warranted to investigate the pathogenicity and role of Aeromonas infection.

Visual closed-tube loop-mediated isothermal amplification (LAMP) assay targeting aerolysin gene: a practical screening method for virulent Aeromonas species affecting cultured eels in China

Under intensive and high-density aquaculture conditions, the cultured eels are easily infected by a variety of virulent Aeromonas species, which leads to high mortality rates and economic losses. In this study, a visual closed-tube loop-mediated isothermal amplification (LAMP) assay was developed for targeting aerolysin gene of Aeromonas species affecting cultured eels. Firstly, two pairs of outer and inner primers were designed against a conserved region of the aer gene from different Aeromonas species. Secondly, the weakly buffered aer-LAMP assay was optimized under various Mg2+ concentrations, different amplification times and amplification temperatures followed by the visual evaluation of phenol red dye and SYTO-9. Thirdly, the detection limit of the aer-LAMP assay showed 16.8 copy/μl which was simultaneously evaluated by the color changes from red to yellow and the real-time fluorescence amplification curves. The specificity of the aer-LAMP assay showed no cross-reaction with other related species. In addition, 30 Aeromonas strains and 40 clinical tissues from eels were used to further validate the effectiveness of the aer-LAMP assay. All the results showed that the aer-LAMP assay provided a rapid, simple, and reliable method for detecting Aeromonas harboring the aerolysin gene, which would be helpful for the prevention and control of Aeromonas infection in cultured eels.

Infección gastrointestinal por Aeromonas: incidencia y su posible relación con la enfermedad inflamatoria intestinal

IntroductionAeromonas can cause several diseases in humans, with gastroenteritis accounting for most cases. The role of Aeromonas as a pathogen in human enterocolitis has been questioned in recent years. ObjectiveTo determine the incidence of gastrointestinal infection caused by Aeromonas in our area and its possible relationship to inflammatory bowel disease. Patients and methodsThis was a retrospective observational study. All adult patients with a positive stool culture for Aeromonas were identified between January 2015 and December 2017 at Hospital Galdakao-Usansolo (Vizcaya, Spain). ResultsNinety-eight patients were identified (median age 62 years; 51% women). Therefore, the incidence in our area was 32 cases per 105 inhabitants per year. Eleven per cent of them had been previously diagnosed with inflammatory bowel disease (four with ulcerative colitis and seven with Crohn's disease). Patients with inflammatory bowel disease more often received immunosuppressive therapy. Conversely, patients without inflammatory bowel disease suffered from more comorbidities. We also found comorbidity to be the risk factor most associated with Aeromonas infection. ConclusionAeromonas infection is a common gastrointestinal infection that may occur in both immunocompetent and immunocompromised patients. Immunosuppression is a significant factor in inflammatory bowel disease patients, while comorbidity seems to confer a higher risk on patients without this disease.

Histopathological and Hematological studies on Cephalosporin used in Treatment of Nile tilapia (Oreochromas niloticus) fish against Aeromonas hydrophila infection

This work was conducted to study the effect cefquinome in treatment of Aeromonas hydrophila in Nile tilapia and their effect of hematological and histopathological findings. One hundred and thirty five Nile tilapia fish were used and divided into 3 equal groups. 1st groups served as a negative control while 2nd group was positive group that injected with A. hydrophila. Cefquinomesulphate (Cobactan® 2.5%) injectable suspension was given as a single intramuscular dose of 10 mg/kg body weight (therapeutic dose) to A. hydrophila-experimentally infected fish (group 3). The mortality rate decreased after treatment by cefquinome from 66.6 % to 17.7 %, and the clinical signs improved in comparison to the experimentally infected non treated group. Cefquinome treatment showed a significant improvement in all hematological parameters of experimented tilapia at 14th day post medication. Moreover, the histopathological findings showed an improvement in the infected-treated group in comparison to infected non-treated one. The result concluded that, cefquinome is effective in treatment Nile tilapia fish against Aeromonas infection and improve their health status by time dependent manner. The present result concluded that, cefquinome is effective in treatment Nile tilapia fish against Aeromonas infection through improving the histopathological and hematological findings.

A review of functional feeds and the control of Aeromonas infections in freshwater fish

To limit the use of antibiotics in farmed fish and their potential negative impacts on public health and the environment, an evaluation of “functional alternatives” is required. The availability of effective treatments to control fish diseases is one of the most significant challenges facing aquacultures and veterinarians to reduce consequences of antimicrobial resistance. This paper includes results from in vivo studies in major freshwater-farmed fish species (salmonids, cyprinids, and cichlids), focusing on the efficacy of functional alternatives against Aeromonas spp. infections. It also outlines the recent biocontrol advances and potential alternative treatments in aquaculture. Functional alternative products can increase the resistance against Aeromonas spp. particularly by increasing the immunocompetence of fish. Many diverse alternative products such as probiotics, prebiotics, plants, essential oils, algae phages, minerals, and nanoparticles have been tested, but the diversity of the experimental designs makes it difficult to compare the efficacy of the tested products. It suggests the standardization of investigations on functional feed products for each fish species against a specific pathogen. This review also recommends farm research on functional feed alternatives in natural conditions in order to evaluate the decrease of antibiotic consumption in fish farms.

Isolation, Characterization, and Application of a Bacteriophage Infecting the Fish Pathogen Aeromonas hydrophila.

Bacteriophages are increasingly being used as biological control agents against pathogenic bacteria. In the present study, we isolate and characterize bacteriophage Akh-2 from Geoje Island, South Korea, to evaluate its utility in controlling motile Aeromonas septicemia. Akh-2 lysed four of the seven Aeromonas hydrophila strains tested. Transmission electron microscopy analysis showed that Akh-2 belongs to the Siphoviridae family, with head and tail sizes of 50 ± 5 and 170 ± 5 nm, respectively. One-step growth curve analysis revealed that the phage has a latent period of 50 ± 5 min and a burst size of 139 ± 5 plaque-forming units per infected cell. The phage appeared stable in a pH range of 6–8 and a temperature range of −80 to 46 °C. Based on next-generation sequencing analysis, its genome is 114,901 bp in size, with a 44.22% G + C content and 254 open reading frames. During an artificial induction of the disease, loach (Misgurnus anguillicaudatus) treated with Akh-2 showed an increased survival rate and time compared with the non-treated control. Our results suggest that Akh-2 is a potential biological agent for the treatment of Aeromonas infections in fish.

Clinical features and laboratory data analysis of Aeromonas bacteremia with hematological diseases

目的分析患有血液系统疾病患者气单胞菌血流感染的临床及实验室特征，为该类患者气单胞菌感染的防治提供依据。方法回顾性分析中国医学科学院血液病医院2014年1月至2018年12月5年发生气单胞菌血症的血液系统疾病患者，收集患者临床感染特征、菌株耐药性、发生季节、治疗及转归情况等相关信息。结果共42例血液病患者发生气单胞菌血流感染，其中39例（92.9%）血流感染发生于粒细胞缺乏（粒缺）期，平均发热时间为4（1~27）d，22例（52.4%）患者症状仅为发热，6例（14.3%）伴消化道症状（腹痛、腹泻、恶心、上消化道出血），8例（19.0%）伴肺部感染，13例（31.0%）伴皮肤软组织感染。7例（16.7%）患者死亡，且均伴皮肤软组织感染。气单胞菌对碳青霉烯类抗菌药物的耐药率为68.3%~70.7%，而对头孢菌素类、喹诺酮类及氨基糖苷类抗菌药物的耐药率均小于10%。结论血液系统疾病合并气单胞菌血流感染主要发生在粒缺期，主要以发热为主，当伴有皮肤软组织感染时死亡率高。抗菌药物选择应依据药敏结果，避免使用碳青霉烯类抗菌药物。

Emerging carbapenem-resistant Aeromonas spp. infections in Cali, Colombia

IntroductionAeromonas species are renowned enteric pathogens with virulence determinants linked to human diseases, such as gastroenteritis, skin, soft-tissue and muscle infections, and septicemia. A recent concern of resistance in this organism has emerged, especially the presence carbapenemases. Herein we describe a case series of emerging carbapenem-resistant Aeromonas species infection in our hospital in Cali, Colombia. Materials and methodsCases from 2012 to 2018 are reported. Clinical data was abstracted from the clinical charts and laboratory information. Phenotypic detection of resistance was identified using the VITEK®2 system (BioMérieux) and broth microdilution MicroScan WalkAway plus System (Beckman Coulter). CARBA NP-test and multiplex qPCR assay was performed in 11 isolates to identify genes encoding carbapenemases (blaKPC, blaVIM, blaIMP and blaNDM). Results21 cases of Aeromonas infection in hospitalized patients with phenotypic resistance to carbapenems were studied. The median age was 50 years, 55% (12/21) were male, and 67% (14/21) were healthcare-associated infections (HAI). Aeromonas hydrophila was the most common species (19/21). Forty-three percent (9/21) of the patients were immunocompromised. The mortality was 33% (7/21), and in patients with bacteremia was 100%. Most patients received empirical treatment with meropenem and failed to this treatment. PCR amplification tests showed negative results for the carbapenemases analyzed. ConclusionEmerging phenotypic carbapenem-resistant infection has been seen in our hospital, most as HAI. High mortality was found, especially in immunocompromised patients and in those who failled empirical treatment with carbapenems. As the main carbapenemases tested were negative, carbapenem-resistant could be attributed to an intrinsic metallo-β-lactamase, CphA encoded by the cphA gene, possible hyperproduction of ampC β-lactamase and/or porins expression.