Biochemical and Molecular Identification of the Most Common Streptococci Affecting Common pandora (Pagellus erythrinus Linnaeus, 1758) From the Mediterranean Coast of Tripoli

Streptococcosis is one of the septicaemic bacterial diseases of public health concern due to its zoonotic potential. Its luxurious existence in wild marine fish from an open water body strongly suggests presence of massive sewage pollution. The aim of the current study was to identify and characterize most common streptococci  affecting common pandora (Pagellus erythrinus) inhabiting the Mediterranean coast of Tripoli. A total number of 270 common pandora  were clinically examined for possible streptococcal infection and non-streptococcal infection. The fishes were collected from the area extending from Tripoli to Tajoura (east to Tripoli) during the three seasons, summer, autumn, and spring. No fish samples were available during winter due to the bad climate / storms along the entire western Libyan Mediterranean coasts. Streptococcus iniae, Streptococcus dysgalactiae, Streptococcus phocae, Enterococcus faecalis, and other non-streptococcal species, such as Aeromonas hydrophila, Pseudomonas anguilliseptica, and Photobacterium damselae sub species damselae were biochemically identified. Regardless of the season, S. iniae and E. faecalis were the most prevalent streptococcal species (13% and 8.88%, respectively). In contrast, the most retrieved non-streptococcal species were A. hydrophila, followed by Pseudomonas anguilliseptica, with a prevalence of 10%, and 14.44%, respectively. The highest infections were recorded during autumn, followed by summer, then spring with percentages of 53.34%, 50%, and 43.4%, respectively. The majority of the isolates were sensitive to erythromycin, florfenicol, and sulfamethoxazole-trimethoprim. The molecular screening using the sequences of 16S rRNA genes has confirmed the phylogenetic relationship to S. dysgalactiae, E. faecalis, S. iniae, and S. phocae isolates with similarity percentages exceeding 99.6%. The sequences were deposited in the GenBank with accession numbers (OK033868, OK033869, OK033870, and OK033871). To sum up, the obtained results highly suggests that the common pandora fish from Tripoli coast of the Mediterranean is biologically contaminated with various zoonotic streptococci which could be considered as a biological indicator for municipal sewage pollution.