Chemotherapeutic control of Gram-positive infection in white sea bream (Diplodus sargus, Linnaeus 1758) broodstock

Abstract

Aim: This study aimed to identify the pathogenic bacteria responsible for the septicemic disease affecting white sea bream brooders and determining the sensitivity of the recovered isolates to different antibiotics followed by estimation of long-acting oxytetracycline (OTC) efficacy in controlling this disease, and finally, determining the proper dose regimen. Materials and Methods: Biolog microbial identification system was used for determination of the pathogens which are responsible for this disease. Agar disk diffusion test and minimum inhibitory concentration (MIC) were used to determine the antibiotic susceptibility of recovered isolates. Oxytetracycline (OTC) was used at a dose level of 100 mg/kg body weight for the treatment of diseased fish, and the OTC concentration in the serum samples was determined by high-performance liquid chromatography. Results: Fifteen Staphylococcus epidermidis and 11 Bacillus cereus isolates were recovered from the lesion of muscle, tail, eye, and heart blood. S. epidermidis isolates were sensitive to OTC, ciprofloxacin, enrofloxacin, spiramycin, erythromycin (E), and florfenicol. B. cereus isolates were sensitive to all mentioned antibiotics except E. Based on the MIC test, all B. cereus isolates were sensitive to OTC with MIC ranging between <0.125 and 4 μg/ml and 11 S. epidermidis isolates were sensitive with MIC ranging between <0.125 and 8 μg/ml, while four isolates were resistant. Different degrees of degenerative changes were present in the hepatopancreas, posterior kidney, eye, and skin tissues of diseased fish. Conclusion: Single intraperitoneal injection of long-acting OTC at a dose of 100 mg/kg body weight was effective in termination of S. epidermidis and B. cereus infection in white sea bream (D. sargus) broodstock.

Newly Emerging MDR B. cereus in Mugil seheli as the First Report Commonly Harbor nhe, hbl, cytK, and pc-plc Virulence Genes and bla1, bla2, tetA, and ermA Resistance Genes

“…Bacillus cereus is a ubiquitous bacterium of public health concern and has recently been categorized as a fish-threatening pathogen, causing huge economic losses in the aquaculture sector. 28 In the current study, the results of clinical and postmortem inspections were congruent with Ali 27 who observed deep hemorrhagic skin ulcers, unilateral exophthalmia, tail rot, and congested parenchymatic organs in white seabream (Diplodus sargus) suffered from a mixed infection with Staphylococcus epidermidis and B. cereus. Similar results have been reported in infected stinging catfish, 28 and seabass with B. cereus.…”

Multifaceted applications of probiotic Bacillus species in aquaculture with special reference to Bacillus subtilis

“…2016; Ali et al . 2019). Nevertheless, enterotoxigenic B. cereus strains are found to colonize in the intestine of fish (Prasad 2014).…”

“…Among various Bacillus species, B. cereus is often associated with various types of infections in fish species (Pychynski et al 1981;Baya et al 1992;Oladosu et al 1994;Chandra et al 2015;Aboyadak et al 2016;Ali et al 2019). Nevertheless, enterotoxigenic B. cereus strains are found to colonize in the intestine of fish (Prasad 2014).…”

Omics Strategies in Current Advancements of Infectious Fish Disease Management

“…This has proven to be a challenge as several pathogens are responsible for increasing the mortality of farmed fishes. Fish farmers have incorporated pesticides, chemotherapeutic agents, and antibiotics in dealing with pathogenic infection on a large scale [ 61 , 62 ]. While all these strategies have their pros, the long-term disadvantages are overwhelming the advantages.…”