Detection and description of a novel Psychrobacter glacincola infection in some Red Sea marine fishes in Hurghada, Egypt

Abstract

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.

Influence of host phylogeny and water physicochemistry on microbial assemblages of the fish skin microbiome

“…Psychrobacter spp. includes opportunistic pathogens in both fish and humans and is the causative agent of disease in Red Sea marine fish (El-Sayed et al 2023 ). However, P. nivimaris and P. faecalis have also been documented to have probiotic qualities, reducing mortality rates in juvenile turbot ( Scophthalmus maximus ) exposed to Tenacibaculum maritimum (see Wuertz et al 2023 ).…”

“…This may also change in response to environmental stressors and disease. For example, the genus Psychrobacter contains both opportunistic pathogens and symbionts, with thus both a protective function but also a disease-causing impact (El-Sayed et al 2023 , Wuertz et al 2023 ). It is well-established that when fish are stressed, their microbiomes are perturbed leading to an increase in the abundance of opportunistic pathogens, which may lead to the development of disease (Minniti et al 2017 ).…”

Abundance and Diversity of Several Bacterial Genera in the Mariculture Environment

“…This susceptibility is evidenced by the increasing frequency and intensity of recorded disease outbreaks in many marine taxa worldwide [2]. The recent uptick in such outbreaks [3] may be attributed to the introduction of new pathogens or environmental changes [2,[4][5][6][7]. Bacteria, fungi, viruses, oomycetes, amoebas, and other ectoparasites have emerged as causal agents of several diseases that limit fish and shellfish production [8].…”