Occurrence and pathogenicity of serratia marcescens at fish farms in Kafr El-Sheikh Governorate

الملخص EN

An investigation was carried out for unusual disease outbreaks occurred on 5 commercial oreochromis Nilotic us (O.niloticus) fish farms during the period 2003–2004, in 3 Districts in Kafr El-Sheikh Governorate.

Affected fish exhibited anorexia, sluggishness, variously sized areas of hemorrhage on the skin, corneal opacity and high mortality up to 21.4 %.

Bacterial isolates from the moribund fish were identified as Serration marcescens (S.marcescens) by biochemical tests revealed 28 isolates.

The virulence properties of this isolates, studied revealed that were highly pathogenic for fish with LD50s ranging from 5 x 103 to 1 x 105.

Moreover, the isolates were pathogenic for mice with LD50 1.6 x 106.

Histopathologically alterations of the natural and experimental infections are described.

The antibiogramme of the isolated S.marcescens was investigated.

This study is considered the first record of S.marcescens infection in O.niloticus fish in Egypt.