Evaluation of an in vitro cell assay to select attenuated bacterial mutants of Aeromonas hydrophila and Edwardsiella tarda to channel catfish

2011 ◽  
Vol 111 (6) ◽  
pp. 1310-1318
Author(s):  
J.W. Pridgeon ◽  
P.H. Klesius ◽  
X. Mu
2017 ◽  
Vol 22 (3) ◽  
pp. 331-339 ◽  
Author(s):  
Luisa Marcela Villamil Díaz ◽  
Daniel Esguerra Rodríguez

Se aislaron 120 morfotipos bacterianos de intestino de tilapia y se seleccionaron según su actividad antibacteriana contra patógenos como Aeromonas hydrophila, Streptococcus agalactiae y Edwardsiella tarda, su capacidad de adherencia a mucus intestinal y cinética de crecimiento. Las bacterias seleccionadas se identificaron mediante secuenciación de 16S rRNA y se identificaron como Exigobacterium sp. I9, Enterococcus faecalis I15 y Myroides odoratimimus I19. Además, se evaluó su efecto in vivo sobre el crecimiento de los peces, mediante su adición al alimento de juveniles de Oreochromis niloticus (106 UFC / g, por 15 días). Se determinó la supervivencia luego de un desafío experimental con Edwardsiella tarda por inyección intraperitoneal (100 µL 105 UFC / mL). Las tres bacterias seleccionadas incrementaron la tasa de crecimiento específica, redujeron la mortalidad de los peces durante el desafío experimental con E. tarda y no causaron mortalidad durante la adición en el alimento. Los efectos positivos in vivo se relacionan posiblemente con actividad in vitro; sin embargo, por motivos de bioseguridad se recomienda efectuar estudios posteriores a Exigobacterium sp. I9y E. faecalis I15 dado que se han reportado miembros de este género como causantes de mortalidad en peces, mientras que en el caso de M. odoratimimus I19, es necesario efectuar futuros estudios para verificar su actividad positiva a mayor escala productiva.


1970 ◽  
Vol 7 (1) ◽  
pp. 163-168 ◽  
Author(s):  
T Rahman ◽  
MMR Akanda ◽  
MM Rahman ◽  
MBR Chowdhury

An experiment was conducted to compare the efficacies of some selected antibiotics and medicinal plants against common bacterial fish pathogens viz., Aeromonas hydrophila, Pseudomonas fluorescens and Edwardsiella tarda. Four different antibiotics viz., CFCIN (ciprofloxacin), Renamycin (oxytetracycline), DT-10 (doxycicline) and Sulfatrim (sulphadiazine + trimethoprim) were exposed in different doses (100, 75, 50 and 25 ppm) to the culture of freshly isolated bacteria under the in vitro condition for sensitivity test and minimum inhibitory dose (MID) was determined. Based on in vitro results, antibiotics were applied to the experimental infection of Thai silver barb, Barbonymus gonionotus. CFCIN showed the best result with 100% recoveries of challenged fish in prolonged bath treatment. Medicinal plants were selected on the basis of previous studies. Crude extracts were prepared from various parts (leaves and bulb) of garlic, turmeric, akand and neem and four different doses were applied to the fresh culture of pathogenic isolates under the in-vitro condition to determine minimum inhibitory dose (MID). However, garlic offered the best result with 90.00 ± 2.89% recoveries of challenged fish in aquarium trial. Akand + neem, turmeric and akand showed moderate to weak recovery rates with the same dose. The present study thus showed that medicinal plants would be an effective control measure along with antibiotics against bacterial fish diseases. Keywords: Efficacy; Medicinal plants; Bacterial fish pathogens DOI: 10.3329/jbau.v7i1.4980 J. Bangladesh Agril. Univ. 7(1): 163-168, 2009


2018 ◽  
Vol 09 (02) ◽  
Author(s):  
Soumyadip Purkait ◽  
Thangapalam Jawahar Abraham ◽  
Sutanu Karmakar ◽  
Biswadeep Dey ◽  
Anwesha Roy

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 631
Author(s):  
Mengfan Peng ◽  
Wentao Tong ◽  
Zhen Zhao ◽  
Ling Xiao ◽  
Zhaoyue Wang ◽  
...  

In this experiment, the quorum quenching gene ytnP of Bacillus licheniformis T-1 was cloned and expressed, and the effect against infection of Aeromonas hydrophila ATCC 7966 was evaluated in vitro and vivo. The BLAST results revealed a 99% sequence identity between the ytnP gene of T-1 and its homolog in B.subtilis sub sp. BSP1, and the dendroGram showed that the similarity in the YtnP protein in T-1 was 100% in comparison with B.subtilis 3610, which was categorized as the Aidc cluster of the MBL family. The AHL lactonase activity of the purified YtnP was detected as 1.097 ± 0.7 U/mL with C6-HSL as the substrate. Otherwise, purified YtnP protein could significantly inhibit the biofilm formation of A.hydrophila ATCC 7966 with an inhibition rate of 68%. The MIC of thiamphenicol and doxycycline hydrochloride against A. hydrophila reduced from 4 μg/mL and 0.5 μg/mL to 1 μg/mL and 0.125 μg/mL, respectively, in the presence of YtnP. In addition, YtnP significantly inhibited the expression of five virulence factors hem, ahyB, ast, ep, aerA of A. hydrophila ATCC 7966 as well (p < 0.05). The results of inhibition on virulence showed a time-dependence tendency, while the strongest anti-virulence effects were within 4–24 h. In vivo, when the YtnP protein was co-injected intraperitoneally with A. hydrophila ATCC 7966, it attenuated the pathogenicity of A. hydrophila and the accumulated mortality was 27 ± 4.14% at 96 h, which was significantly lower than the average mortality of 78 ± 2.57% of the Carassius auratus injected with 108 CFU/mL of A. hydrophila ATCC 7966 only (p < 0.001). In conclusion, the AHL lactonase in B. licheniformis T-1 was proven to be YtnP protein and could be developed into an agent against infection of A. hydrophila in aquaculture.


1987 ◽  
Vol 31 (sa) ◽  
pp. 203-208 ◽  
Author(s):  
T. G. Clark ◽  
H. W. Dickerson ◽  
J. B. Gratzek ◽  
R. C. Findly

2016 ◽  
Vol 113 (3) ◽  
pp. 722-727 ◽  
Author(s):  
Duraisamy Ponnusamy ◽  
Elena V. Kozlova ◽  
Jian Sha ◽  
Tatiana E. Erova ◽  
Sasha R. Azar ◽  
...  

Necrotizing fasciitis (NF) caused by flesh-eating bacteria is associated with high case fatality. In an earlier study, we reported infection of an immunocompetent individual with multiple strains of Aeromonas hydrophila (NF1–NF4), the latter three constituted a clonal group whereas NF1 was phylogenetically distinct. To understand the complex interactions of these strains in NF pathophysiology, a mouse model was used, whereby either single or mixed A. hydrophila strains were injected intramuscularly. NF2, which harbors exotoxin A (exoA) gene, was highly virulent when injected alone, but its virulence was attenuated in the presence of NF1 (exoA-minus). NF1 alone, although not lethal to animals, became highly virulent when combined with NF2, its virulence augmented by cis-exoA expression when injected alone in mice. Based on metagenomics and microbiological analyses, it was found that, in mixed infection, NF1 selectively disseminated to mouse peripheral organs, whereas the other strains (NF2, NF3, and NF4) were confined to the injection site and eventually cleared. In vitro studies showed NF2 to be more effectively phagocytized and killed by macrophages than NF1. NF1 inhibited growth of NF2 on solid media, but ExoA of NF2 augmented virulence of NF1 and the presence of NF1 facilitated clearance of NF2 from animals either by enhanced priming of host immune system or direct killing via a contact-dependent mechanism.


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