Vol 3 (1) 2011 - UBM :: Departamentul de Chimie-Biologie

H. El-Sayed M. Farag, Concentration of antibiotics residues in farmed tilapia and their relationship to resistant
Aeromonas strains
CONCENTRATION OF ANTIBIOTICS RESIDUES IN FARMED TILAPIA
AND THEIR RELATIONSHIP TO RESISTANT AEROMONAS STRAINS
Hassan El-Sayed M. Farag*
Food Hygiene Dept., Animal Health Research Institute, Port-Said Lab., Egypt
* has_far1@yahoo.com
ABSTRACT
Three groups of fresh tilapia, Oreochromis niloticus, were randomly collected from farms at Port-Said
Governorate, Egypt for qualitative and quantitative detection of antibiotic residues by microbiological assay method
and HPLC. The sensitivity of isolated Aeromonas strains for oxytetracycline was also evaluated. The detections of
antibiotic residues in tilapia samples were found in a percentage of 100% (60), 80% (48) and 0.00% (0.00) for group
I, II and III respectively. The detected antibiotics were from the tetracycline and ß–lactam groups. The mean
concentrations of the oxytetracycline residual level in tilapia muscle assessed were 319.92 ± 12.18, 142.14 ± 4.86
and 75.49 ± 1.66 ppb for group I, II and III respectively. The isolated strains of Aeromonas species in the examined
samples were various among the examined groups and phenotypic identified as A. caviae, A. scubertii, A.
hydrophila, A. trota and A. sobria. The incidence of oxytetracycline resistance Aeromonas strains in group I and II
were 100% for each, while 35.71% of the isolated strains in the group III were resistant to oxytetracycline.
Antibiotics residues are seemed to quality defects in farmed tilapia that facing the challenges of the fish exporting in
Egypt. Application of good manufacture practices and Hazards Analysis Critical Control System (HACCP) in tilapia
farms must be done for improving the antibiotics residual problem in fish muscles.
Keywords: Fish, microbiological assay, oxytetracycline, Bacteria.
.
1. Introduction
Aquaculture has been considered one
of the fastest growing segments of the global
food production sector in recent decades [1].
In comparison to other farmed animals, fish
are generally very efficient converters of
feedstuffs into high quality protein [2].
Tilapias, Oreochromis niloticus, have
become the third most important fish in
aquaculture that cultured in many tropical
and subtropical regions. It is characterizes by
high yields in a short period on relatively
low nutritional inputs and high palatability
[2].
Member of the genus Aeromonas are
ubiquitous in most aquatic environments
through the world [3]. Several strains have
been implicated in fish disease as
Aeromonas hydrophila, A. Sobria, A.
allosacchharophila, A. Salmonicida and A.
veronii [4]. Aeromonas hydrophila is one of
the most important agents of the outbreaks in
fresh water fish, in which skin ulcer,
44
hemorrhage and necrosis of the visceral
organs are the major symptoms of
Aeromonad septicemia [5]. Diseases
outbreaks due to Aeromonas species are
responsible for high economic losses in both
intensively and extensively cultured fish as
well as in wild fish [6] as a result of high
mortality and deterioration of product
quality [7, 8 ]. Some strain of Aeromonas
species such as Aeromonas hydrophila, A.
veronii, A. jandaei, A. trota and A. schubertii
have been emerged as opportunistic human
pathogens [9] which responsible for
foodborne gastroenteritis, pneumonia,
peritonitis, endocarditis, meningitis,
septicaemia, urinary tract infection and
wound and skin infection specially in
compromised patients [10, 11].
The potential for disease problems
associated with intensive fish culture would
increase the probability of the use of
antimicrobial drugs to treat a variety of
bacterial infection [12] beside promoting the