Impairment of Bioenergetic Function and Loss Ions Regulation in Cyprinus carpio Experimentally Infected with Providencia alcalifaciens: Biochemical and Histopathology Study

It is a scientific fact that bacteria cause disturbance in energy metabolism. Studies about the Providencia spp. in carp fish are rare. Therefore, the study aimed to molecularly reisolate and investigate Providencia's effect on enzymes of the phosphorylation network as creatine kinase (CK), ionic balance in the serum and semi-quantitative and histochemistry analysis of the gill tissue. Thirty fish were divided into three groups: control group, second and third fish were intraperitoneal injected with 108 ×12 and 108×6 CFU, respectively. The 16S rRNA gene sequence was related to Providencia alcalifaciens. The statistical analysis showed a significant decline (P ≤ 0.05) of the CK and a loss of ionic balance (Na⁺, K⁺, Cl^─, and Ca⁺⁺) in the two study groups compared to the control group. The semi-quantitative analysis of the gills arch and filaments showed pathological alteration occupied score (0-3), moreover the histological alteration index (HAI) was highly significant (P≤ 0.01) in both groups from 216 and 136. The histochemistry analysis of the mucocytes showed positive reactivity for Alcian Blue stains for acid mucus secretion. Additionally, mucocytes were highly significantly distributed (P≤ 0.05) at the apex of filaments. In conclusion, the decrease in the concentration of CK is an indicator of the effect of Providencia on energy metabolism as well as the disturbance of the ionic balance. This leads to pathological lesions in the gills. Moreover, the semi-quantitative and statistical analysis of histological lesions and histochemistry analysis are considered evidence of the significance and severity of the lesions.