An important food-producing sector in Egypt is aquaculture and fisheries; however, several pathogenic microorganisms lead to high mortalities and significant economic losses. The occurrence of Psychrobacter glacincola infection among 180 wild marine fishes collected from the Red sea at Hurghada, Egypt were investigated in the present study. The disease prevalence rate was 6.7%. The recovered isolates were subjected to biochemical and molecular identification. The study also investigated pathogenicity and the antibiogram profile of the recovered isolates. The clinical examination of the infected fish revealed various signs that included lethargy and sluggish movement, hemorrhages and ulcers on the body and the operculum, scale loss, and fin congestion and rot, especially at the tail fin. Furthermore, during postmortem examination, congestion of the liver, spleen, and kidney was observed. Interestingly, 12 isolates were recovered and were homogenous bacteriologically and biochemically. The phylogenetic analysis based on 16S rRNA gene confirmed that MRB62 identified strain was closely related the genus Psychrobacter and identified as P. glacincola and was pathogenic to Rhabdosargus haffara fish, causing 23.3% mortality combined with reporting a series of clinical signs similar to that found in naturally infected fishes. The present study also showed that P. glacincola isolates were sensitive to all antibiotics used for sensitivity testing. Our findings add to the body of knowledge regarding the occurrence of pathogenic P. glacincola infection in Egyptian marine fishes and its potential effects on fish. Future large-scale surveys exploring this bacterium among other freshwater and marine fishes in Egypt would be helpful for the implementation of effective strategies for the prevention and control of this infection are warranted.
Micrococcus luteus (M. luteus) is an emerging opportunistic fish pathogen. This study was carried out to investigate incidence of M. luteus infection among Oreochromis niloticus (O. niloticus) farms at Al Dakhla city, New Valley Governorate, Egypt through clinical and bacteriological examinations and to determine antimicrobial susceptibility of M. luteus isolates and the minimum inhibitory concentration (MIC) of silver nanoparticles (AgNPs) and zinc oxide nanoparticles (ZnONPs) against M. luteus isolates. O. niloticus samples (n=150) were collected from several farms at Al Dakhla city from March to October 2019 and they were clinically and bacteriologically examined. Suspected isolates were identified as M. luteus by the morphological and biochemical characteristics then by 16S rRNA gene sequencing and phylogenetic analysis where 14 isolates were identified as M. luteus from the examined O. niloticus with prevalence of 9.3%. M. luteus isolates were biochemically identical except in arginine dehydrolase, Vogus-Proskauer and urease tests results. O. niloticus infected with M. luteus showed excessive skin pigmentation, loss of scales, hemorrhages and ulcers on the body, congestion and rot of fins, corneal opacity, exophthalmia and congested enlarged liver, spleen and kidney. Antimicrobial susceptibility of M. luteus isolates revealed that they were sensitive to penicillin, ampicillin/sulbactam, amoxicillin/clavulanic acid, norfloxacin, chloramphenicol and tetracycline, while were resisantant to cefotaxime, amikacin, tobramycin, erythromycin and ciprofloxacin. Furthermore, it was found that MIC of AgNPs against M. luteus isolates was 100µg/ml while M. lutues isolates were resistant to all ZnONPs concentrations used in this study. This study reported fish infection with M. luteus for the first time in Egypt and its results will be a starting point for the further studies to investigate prevalence and distribution of M. luteus infection among fishes in Egypt and the plan of its prevention.
Bacteria are one of the most prevalent causes of morbidity and mortality among wild fishes. Vibrio alginolyticus (V. alginolyticus) is a serious fish pathogen. This study was performed to investigate prevalence of V. alginolyticus infection among six species of Red Sea fishes at Hurghada city, Egypt through clinical and bacteriological examinations and to determine pathogenicity of the isolates and their antimicrobial susceptibilities. Therefore, a total number of 180 fish from these six fish species (30 fish of each species) were randomly collected from the Red Sea at Hurghada city during the period from October 2019 to March 2020 and subject to clinical and bacteriological examinations. Based on the morphological and biochemical characteristics of the isolates, 64 homogenous V. alginolyticus isolates were isolated and phenotypically identified from the examined fishes with prevalence of (26.7%), (20%), (63.3%), (36.7%), (23.3%) and (43.3%) among Lutjanus ehrenbergii (L. ehrenbergii), Lethrinus borbonicus (L. borbonicus), Siganus rivulatus (S. rivulatus), Rhabdosargus haffara (R. haffara), Scarus ghobban (S. ghobban) and Cheilinus lunulatus (C. lunulatus) fishes respectively. Afterthat, representative isolates were cofirmed as V. alginolyticus by 16S rRNA gene sequence and deposited in GenBank as V. alginolyticus MR-C17 (GenBank accession no. MW790239). The V. alginolyticus infected fishes exhibited skin dark coloration, scales loss, hemorrhages on several parts of the body surface, mouth, base of fins, abdomen, opercula and around the anal opening, eroded fins, ascites, swollen intestine and congestion or paleness of the internal organs espeially liver. Antimicrobial susceptibility testing of V. alginolyticus isolates revealed that they were sensitive to chloramphenicol, tetracycline, ciprofloxacin and ofloxacin and resistant to ampicillin, cephalothin, amikacin, streptomycin, cefotaxime, erythromycin, oxolonic acid, amoxicillin/clavulanic acid, tobramycin and clindamycin. Pathogenicity test revealed that V. alginolyticus MR-C17 was pathogenic to R. haffara with 80 % mortalities in the experimentally infected fish which showed similar clinical signs and post-mortem (PM) lesions to thoes observed in the naturally infected fishes.
This work aimed to study the effects of Nano-selenium (Nano-Se) supplementation and in-ovo injection on the growth performance and physiological responses of post-hatch chicks reared under hot conditions. A total number of 60 laying hens and 8 cocks Doki-4 strain (74 weeks old and average body weight of female and male 1663.75±34.9 g and 2383.33±147.0, respectively) were randomly divide into two equal groups (30 hens and 4 cocks of each). The first group considered as parents of treatment 1 (Tr1) and treatment 2 (Tr2). The second group considered as parents of treatment 3 (Tr3) and treatment 4 (Tr4). After four weeks of start experiment, 300 fertile eggs collected from two groups (150 eggs / group), the fertile eggs and post-hatch chicks treated as following; Tr1, parents and post-hatch chicks fed on basal diet plus in-ovo injection with 0.5 ml saline solution /egg (control treatment). Tr2, parents and post-hatch chicks fed on basal diet plus in-ovo injection with 0.5 ml saline solution (containing 0.2 µg Nano -Se) /egg. Tr3, parents fed with basal diet supplemented with 0.3 mg Nano -Se /kg feed and post-hatch chicks fed on basal diet plus in-ovo injection with 0.5 ml saline solution (containing 0.2 µg Nano -Se)/ egg. Tr4, parents and post-hatch chicks fed on basal diet supplemented with 0.3 mg Nano -Se /kg feed plus in-ovo injection with 0.5 ml saline solution (containing 0.2 µg Nano -Se) / egg. The results showed that, hemoglobin and mean corpuscular volume significantly (P<0.05) increased in Tr2 and Tr3 in compared to Tr1 (control). Heterophils / lymphocyte ratio and hatchability % significantly (P<0.05) improved in Tr3 and Tr4 in compared to Tr1. Immunoglobulin M significantly (P<0.05) increased in Tr2 and Tr3 in compared to Tr1 and Tr4, rectal temperature significantly (P<0.05) decreased in Tr4 in compared with Tr1, from one day to 6 weeks of age from hatch, Tr3 and Tr4 show better performance in body weight gain, feed intake and feed conversion when compared with Tr1 and Tr2. In conclusion, supplementation the diets of parents and post-hatch chicks with 0.3 mg Nano-Se / kg feed plus in-ovo injection with 0.2 µg Nano-Se /egg enhance growth performance, hematological parameters and immunological responses of post-hatch chicks reared under hot conditions.
Micrococcus luteus (M. luteus) is an emerging opportunistic fish pathogen that results in considerable economic losses among the infected fish. In the present study, a total number of 300 cultured Nile tilapia, Oreochromis niloticus were collected from concrete ponds farms in Alkharga and Aldakhla oases, New Valley governorate during the period from March to July 2019 and subject to clinical and bacteriological examination. The infected fish exhibited excessive skin pigmentation or depigmentation, scales loss, skin hemorrhages, body ulcers, fins congestion and rot, corneal opacity, and exophthalmia. Internally, congested enlarged liver, spleen, and kidney were observed., The prevalence of M. luteus infection was 10.3% and a total number of 31 isolates were recovered from infected fish. These isolates were biochemically similar except for Arginine hydrolysis, Vogus-Proskauer and Urease tests. The isolation and biochemical characterizations suggested that the isolates belong to the genus Micrococcus. The recovered M. luteus isolates were pathogenic to O. niloticus, this is the first report of M. luteus infection in O. niloticus in Egypt.
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