Yersinia ruckeri causes important economic losses for rainbow trout (Oncorhynchus mykiss) farms worldwide. This bacterial disease is likely the most common among trout in Peru; however, no commercial ...vaccine is available nationally, which is, in part, due to a lack of information on the bacterium. The aim of the current study was to characterize 29 Y. ruckeri isolates sampled from seven cage‐reared farms in the Puno Region, the focal point for aquaculture activities in Peru. For this, samples were taken from fish with clinical signs (i.e. haemorrhages, uni‐ or bilateral exophthalmia, hyphaemia and/or melanosis). Notable among our findings was the existence of both Y. ruckeri biotype 1 (9 isolates) and biotype 2 (20 isolates; negative for sorbitol and Tween 80). The isolates further differed in API profiles 5307100 (21 isolates), 1307100 (4 isolates), 1305100 (2 isolates), 1307120 (1 isolate) and 5305100 (1 isolate), with the main differences being in the tests for lysine decarboxylase, gelatine hydrolysis and D‐saccharose fermentation. Despite these differences, all isolates shared identical ERIC‐PCR and REP‐PCR profiles and belonged to the O1a serotype. Fingerprints were identical to the reference strain CECT 955 (serotype O1a). The information obtained will be used for epidemiological purposes by health authorities and for the development of a vaccine against Y. ruckeri, a prominent request made by fish farmers in Peru.
The aim of this study was to isolate and identify Aeromonas species, characterize their virulence genes factors, and to evaluate their lethality in Piaractus brachypomus. Presumptive Aeromonas ...(n = 34) were selected from 44 bacteria retrieved from diseased Amazonian fish. Nineteen isolates were chosen based on fish species, group, the location where were isolated, and colony morphology. Isolates were biochemically and molecularly identified as Aeromonas hydrophila, A. dhakensis, A. veronii, A. jandaei, and A. caviae using API 20E, API 20NE and the analysis of 16 S rRNA and gyrB genes, respectively. Eight virulences genes (aer, altA, act, hly, ser, lip, fla ahyB) were found in one A. dhakensis and two A. hydrophila isolates. A. veronii, A. jandaei, and another two A. hydrophila isolates harbored four, two and three virulence genes, respectively. All A. caviae were fla +, ahyB + and lip +, except two isolates that also presented ser and altA. P. brachypomus (9 ± 1 cm), infected intraperitoneally (4 ×106, 4 ×107, and 4 ×108 CFU/fish), showed susceptibility to all Aeromonas species, each harboring a different virulence genes profile. Both A. hydrophila and A. dhakensis caused > 80% mortality at the lowest evaluated concentration (∼106 CFU/fish). A. veronii and A. jandaei isolates produced 20% and 70% mortality, respectively, using ∼107 CFU/fish, but with lower intensity compared to A. hydrophila and A. dhakensis. At the highest concentration (∼108 CFU/fish), A. veronii caused 70% mortality, while A. caviae isolates caused mortality ranging from 50% to 80%. Remarkably, A. jandei resulted in 100% mortality at this level, similar to A. hydrophila and A. dhakensis. This report confirms the variety of Aeromonas species infecting farmed native Amazonian fish. The study also suggests that virulence genes evaluated in Aeromonas species may not always be an indicator of virulence. Moreover, P. brachypomus, an economically important aquaculture fish species could be susceptible not only to the high mentioned A. hydrophila but also to other less observed species such as A. dhakensis, A. veronii, A. jandaei, and A. caviae, bacteria that should be taken into account in health surveillance for the implementation of aquaculture disease prevention strategies.
Vibrio alginolyticus está asociado a enfermedades en acuicultura. El uso indiscriminado de antibióticos ha conllevado a la búsqueda de alternativas en el tratamiento de enfermedades bacterianas, ...entre ellas la aplicación de bacteriófagos, los cuales infectan y destruyen selectivamente bacterias. En ese sentido, en este trabajo se aisló un bacteriófago altamente lítico a V. alginolyticus el cual fue denominado Va1, con el objetivo de evaluar los parámetros físicos químicos en los cuales es viable. Para esto, se evaluó al bacteriófago Va1 en diferentes condiciones de pH, temperatura, cloroformo. El fago Va1 presenta mayores títulos a 20 y 30 °C y pH de 5 a 8 disminuyendo su viabilidad a partir de 40 °C y en unidades de pH menores de 5. La exposición al cloroformo redujo la viabilidad del fago Va1 en un 25%. A partir de la curva de un paso se determinó que el periodo de latencia y el tamaño de la explosión fueron de 20 minutos y 192 UFP/centro infectivo respectivamente. Al microscopio electrónico de transmisión el fago Va1 evidencio una cabeza icosaedrica y una cola no contráctil, características propias de la familia Podoviridae. En conclusión, el fago Va1 presenta características potenciales para su uso en fagoterapia.
El objetivo del estudio fue describir el desarrollo morfológico del apéndice masculino del camarón de agua dulce Macrobrachium caementarius. Los camarones se colectaron en el río Lacramarca, Perú. Se ...analizaron 56 camarones de entre 13 y 32 mm de longitud total. Luego, cada camarón fue sometido a shock frío para inmovilización y eutanasia. El segundo par de pleópodos de los camarones se extrajo por disección y se mantuvo en solución fisiológica e inmediatamente fue realizada la descripción. El desarrollo del apéndice masculino en el endopodito del segundo par de pleópodos permitió diferenciar seis estados morfológicos. En el Estado 0 se considera a los indiferenciados sexualmente. En el Estado I aparece como una yema. En el Estado II hay crecimiento de la yema. El Estado III posee espinas apicales. El Estado IV presenta espinas subapicales. En el Estado V el apéndice masculino está completamente desarrollado. Los camarones de < 16,21 mm de longitud total no tuvieron apéndice masculino (Estado 0), en cambio aquellos de entre 16,21 mm (Estado I) y 21,60 mm (Estado V) de longitud total fueron diferenciados como camarones machos. El crecimiento del apéndice masculino hasta completar su desarrollo incrementó linealmente con la longitud total del camarón. Los camarones ≥ 16,21 mm de longitud total que no mostraron apéndice masculino observable se consideraron como individuos hembras. La postlarva se diferencia del juvenil y este del adulto (no funcional) por el desarrollo del apéndice masculino y por el tamaño del animal.
Vibrioalginolyticus is associated with diseases in aquaculture. The misuse of antibiotics has led to the search for alternatives in the treatment of bacterial diseases, among them the application of ...bacteriophages that infect and destroy bacteria selectively. In this way, a highly lytic V. alginolyticus bacteriophage, termed Va1, was isolated, with the aim to evaluate its physical chemical parameters. For this purpose, different temperature, pH, chloroform exposure and host range conditions were evaluated. The temperature stability of phage Va1 showed higher titers at 20 and 30 °C decreasing from 40 °C. With respect to pH, the highest titers for the bac-teriophage were between 5 and 8, and chloroform exposure reduced viability of the Va1 phage by 25%. The one-step curve determined that the latency period and the burst size were 20 minutes and 192 PFU / infective center respectively. Under the transmission electron microscope, the Va1 phage showed an icosahedral head and a non-contractile tail, belonging to the Podoviridae family. In conclusion, Va1 phage presents potential characteristics for use in phage therapy
The global ornamental fish trade carries important risk factors for spreading pathogens between different countries and regions, not only for ornamental fish but also for cultured fish and even other ...animal species. In the current study, we reported the capacity of Aeromonas veronii and A. hydrophila isolated from ornamental fish to experimentally infect the reared Amazonian fish Colossoma macropomum. For this, those bacteria were identified, and a primary characterization was performed. Fish were inoculated with 0.1 mL of increasing concentrations of A. hydrophila or A. veronii (C1 = 1 × 102; C2 = 1.8 × 104; C3 = 2.1 × 106; C4 = 2.4 × 108 bacterial cells per mL) in the coelomic cavity. In the control group, fish received the same volume of sterile saline solution (0.9 %). Fish presented petechiae, skin suffusions, and mortality rates up to 100 % according to the inoculum concentration. Histopathologically, fish presented necrosis with karyolysis, loss of the cytoplasmic delimitation of cells of the renal tubules and hepatocytes, hemorrhage, cellular edema, and the presence of bacterial cells. The LD50–96h of A. veronii on C. macropomum was estimated at 2.4 × 106 CFU mL−1 and of A. hydrophila at 1.408 × 105 CFU mL−1. The results demonstrated that it is possible that Aeromonas species isolated from ornamental fish affect C. macropomum, causing similar clinical signs and lesions. This shows the importance of promoting risk control measures worldwide regarding the trade of ornamental fish.
•Aeromonas species from ornamental fish can infect Colossoma macropomum, the most produced Amazonian fish species.•The mortality rate can reach up to 100 % when C. macropomum is experimentally infected with A. hydrophila or A. veronii.•Ornamental fish trade is a major risk factor for disease transmission in aquaculture.
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