Abstract
This study investigated the prevalence of
Staphylococcus aureus
enterotoxin genes and shiga toxin -producing
Escherichia coli
(STEC) in fish and evaluated quality parameters of examined fish. A total of 150 fish samples belonging to 6 species (25/each species) were cultured on Baird–Parker agar and eosin methylene blue agar. Staphylococcal enterotoxin genes and virulence genes (
stx1
,
stx2
, and
eae
A genes) in
E. coli
serotypes were determined by multiplex PCR. Aerobic plate count (APC), Enterobacteriaceae count, coliform count, and
Pseudomonas
count were performed. Also, levels of total volatile base nitrogen and histamine in fish were determined. The prevalence of
S. aureus
ranged from 4% to 36% and count from 2 to 4 log
10
CFU/g. The
sed
,
sea
, and
seb
genes in
S. aureus
isolates were detected with percentages of 40%, 26.6%, and 20%, respectively. The
E. coli
serotype O26 carried
stx
1,
stx2
, and
eaeA
. The APCs, Enterobacteriaceae counts, and
Pseudomonas
counts ranged from 5.1 to 7.2, from 2.01 to 3.9, and from 2.1 to 3.1 log
10
CFU/g, respectively. The most probable number (MPN) of coliform ranged from 1.3 to 3.6 log
10
/g. Levels of total volatile basic nitrogen and histamine ranged from 29.2 to 12.2 and from 0.6 to 4.6 mg/100 g, respectively. Also, the value of thiobarbituric acid was highly significant (1.1 ± 0.084 mg MDA/kg) in
Trachurus mediterraneus
samples compared with those levels obtained from other fish species. Our findings concluded that those fish species could constitute a public health hazard as fish are reservoirs for enterotoxigenic
S. aureus
and Shiga toxin producing
E. coli
strains. This study highlighted the importance of screening of fish for enterotoxigenic
S. aureus
strains and STEC isolates, and also assessing the quality parameters of fish.