LEVOFLOXACIN RESIDUES IN CHICKEN MEAT AND GIBLETS

Abstract

Levofloxacin is a third generation fluoroquinolone used in food-producing animals in some countries outside of EU. The aim of the study was to investigate the residues of this antibiotic in chicken tissues (meat, skin and giblets). Chicken (n=30) were treated with levofloxacin orally at a dose of 10 mg/kg BW for 5 days. Birds were divided into 5 groups and humanely killed as followed: on day 0 (the day after last administration of levofloxacin), 2, 4, 6 and 8 day. The results of the studies showed the highest residues levels of levofloxacin in liver (1051 µg/kg), followed by breast muscle, gizzard, heart and skin – 428 321 303 and 293 respectively. The rate of reduction of antimicrobial activity was different. Tissue concentrations in heart and gizzard decreased faster than these in muscles and skin. In the liver they decreased from the last day of the treatment to the 2nd day and the levels remained nearly equal up to the 8 th day after the end of drug administration.

Full text

Bu lg ar ia n Journal of Veterinary Medicine (201 3) , 16 , Suppl. 1, 216–219
LEVOFLOXACIN RESIDUES IN CHICKEN MEAT AND
GIBLETS
R. KYUCHUKOVA
1
, V. URUMOVA
2
, M. LYUTSKANOV
2
,
V. PETROV
2
& A. PAVLOV
1
1
Department of Food Hygiene and Control, Veterinary Legislation and Management,
2
Department of Veterinary Microbiology, Infectious and Parasitic Diseases, Faculty
of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria;
Summary
Kyuchukova, R., V. Urumova, M. Lyutskanov, V. Petrov & A. Pavlov, 2013. Studies on le-
vofloxacin residues in chicken meat and giblets. Bulg. J. Vet. Med., 16, Suppl. 1, 216–219.
Levofloxacin is a third generation fluoroquinolone used in food-producing animals in some countries
outside of EU. The aim of the study was to investigate the residues of this antibiotic in chicken tissues
(meat, skin and giblets). Chicken (n=30) were treated with levofloxacin orally at a dose of 10 mg/kg
BW for 5 days. Birds were divided into 5 groups and humanely killed as followed: on day 0 (the day
after last administration of levofloxacin), 2, 4, 6 and 8 day. The results of the studies showed the
highest residues levels of levofloxacin in liver (1051 µg/kg), followed by breast muscle, gizzard, heart
and skin – 428 µg/kg, 321 µg/kg, 303 µg/kg and 293 µg/kg, respectively. The rate of reduction of
antimicrobial activity was different. Tissue concentrations in heart and gizzard decreased faster than
these in muscles and skin. In the liver they decreased from the last day of the treatment to the 2nd
day and the levels remained nearly equal up to the 8
th
day after the end of drug administration.
Key words: chicken, levofloxacin,residues
INTRODUCTION
Food-producing animals are treated with a
variety of veterinary drugs, including a
large number of different types of com-
pounds which can be administered in the
feed or in the drinking water. They are
applied in animal husbandry for different
reasons and may lead to residues in milk,
eggs and in other edible tissues. These
residues may include the non-altered par-
ent compound as well as metabolites
and/or conjugates, and have direct toxic
effects on consumers, e.g. allergic reac-
tions in hypersensitive individuals, or an-
tibiotics may cause problems indirectly
through selection of resistant strains of
bacteria (Fàbrega et al., 2008). For con-
trolling the residue problem, the EU has
set maximum residue limits (MRLs) for a
variety of veterinary drugs in milk, eggs
and tissues (Reig & Toldra, 2008; Petersa
et al., 2009).
Antibiotics are widely used in all farm
animals species and residues are often
found in meat, and they should not exceed
the maximal residue limits (Okerman et
al., 2000). Fluoroquinolones are a group
of synthetic antimicrobial agents widely
used both in human and veterinary medi-
cine. These agents exert their antibacterial
effect through the inhibition of DNA gy-
rase, interfering with the supercoiling of
bacterial chromosomal material. As a re-
sult, they have a broad spectrum of activ-
ity against Gram-negative and Gram-

R. Kyuchukova, V. Urumova, M. Lyutskanov, V. Petrov & A. Pavlov
BJVM, 16, Suppl. 1 217
positive bacteria, Mycoplasma spp. and
Rickettsia, including those resistant to
beta-lactam antibiotics and sulphonamides
(Brown, 1996; Ramos et al., 2003).
Since their discovery in the early
1960s, the quinolone group of antibacteri-
als has generated considerable clinical and
scientific interest. Nalidixic acid, the first
used quinolone was obtained as an impu-
rity during the manufacture of quinine.
Since that time, many derivatives have
been synthesised and evaluated for their
antibacterial potency (Andersson & Mac-
Gowan, 2003). A number of new fluoro-
quinolones have become available for use
worldwide since the initial introduction of
ciprofloxacin in the late 1980s (Appel-
baum & Hunter, 2000).
Levofloxacin is a third generation flu-
oroquinolone, an optical isomer of oflo-
xacin having two-fold higher antimicro-
bial activity than the parent compound.
Currently, it is successfully used in human
medicine in the treatment of infections of
upper and lower respiratory tract, genito-
urinary system, skin and soft tissue. This
compound has been applied in food-
producing animals (Patel et al., 2009).
However, the data about residues after
repeated oral administration of levofloxa-
cin in chickens are lacking. Therefore, the
present study was planned to investigate
the residues of this antibiotic in chicken
tissues (meat, skin and giblets).
MATERIAL AND METHODS
The study was conducted on thirty chick-
ens aged two months. Chickens were
treated orally with levofloxacin at a dose
of 10 mg/kg BW via the drinking water
for 5 days. Water was provided ad libi-
tum. Birds were divided into 5 groups and
humanely killed on the day after last ad-
ministration of levofloxacin (day 0), and
on post treatment days 2, 4, 6 and 8.
Breast muscle, liver, gizzard, heart and
skin (with fats) were separated from each
carcass. Samples were weighed and ho-
mogenised with Maximum Recovery
Diluent (MRD, HIMEDIA, India) in an
amount equal to the mass of the sample,
then were centrifuged for 15 min at 2500
min
-1
(for liver samples 20 min). The su-
pernatant was collected and dropped (100
µL) on a medium with the test microor-
ganism Escherichia coli ATCC 25922. It
was inoculated on plain agar (HIMEDIA,
India), previously sterilized and cooled to
50 °C, with concentration of cells 0.5 of
McFarland standard. Sterile plates (90
mm) were filled with 14 mL E.coli ATCC
25922 infected agar as described by
Okerman et al. (1998; 2007). After
incubation for 24 h at 37° C, the widths
of each inhibition zone were measured
from the edge of the sample to the edge of
the inhibition zone. Results were proc-
essed by GraphPad statistical software.
RESULTS AND DISCUSSION
The results of the studies are presented in
Table 1. The data show that the highest
residues levels of levofloxacin were in the
liver (1051 µg/kg), followed by breast
muscle, gizzard, heart and skin – 428
µg/kg, 321 µg/kg, 303 µg/kg and 293
µg/kg, respectively.
Decreasing concentrations of residues
were found in all investigated tissues up
to the 8
th
day after treatment. On the sec-
ond day the levels of gizzard and heart
were below the MRL for fluoroquinolo-
nes. In breast muscle and skin this was
observed on day 4 and in the liver levels
remained high until the 8
th
day after the
end of the treatment (rates with no statisti-
cally significant difference vs previous
days).

Studies on levofloxacin residues in chicken meat and giblets
BJVM, 16, Suppl. 1
218
The rate of reduction of antimicrobial
activity was different for the various tis-
sues. Concentrations of levofloxacin in the
heart and in the gizzard decreased faster
in comparison to the levels in the muscle
and in the skin. After initial decrease in
the liver up to the 2
nd
day after the treat-
ment they remained similar between days
2 and 8. These results were different from
our previous research on tissue concentra-
tion of gatifloxacin (Kyuchukova &
Pavlov, 2012) where the residue levels in
muscles, heart and gizzard were below
MRL on the second day.
Microbiological assays for investiga-
tion of antimicrobial residues are consid-
ered as multi-residue screening tests for
antibiotics in milk, meat or other animal
tissues. Karraouan et al. (2009) used a
microbiological method for the detection
of antibacterial substances in poultry mus-
cles. The method is based on the inhibi-
tion of Escherichia coli growth on agar.
and can be used as a screening method for
the detection of antibiotics in animal tis-
sue.
Devada et al. (2012) studied the safety
of gatifloxacin after repeated oral admini-
stration in broiler chickens and deter-
mined tissue concentration of the drug
following oral administration. The liver
concentration of gatifloxacin was 0.75±
0.04 µg/g after the fourth dose and
0.22±0.07 µg/g after the tenth dose, re-
spectively, whereas in skeletal muscles the
concentration of gatifloxacin was below
the limit of quantification after the fourth
dose. Gatifloxacin was not detected after
the tenth dose of.
In conclusion it should be noted that
the proposed withdrawal period of eight
days for levofloxacin is applicable in all
tissues with exception of the liver, where
relatively high values persisted after the
end of the study. Therefore we could state
that chicken meat producers have to keep
in mind withdrawal period of veterinary
drugs used in their farms.
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Table 1. Levofloxacin residue levels (µg/kg) in the meat and in the giblets (mean ± SD; n=6)
Days after the end of the treatment
Tissue samples 0 2 4 6 8
Muscle 428 ± 253 105 ± 52 68 ± 10 68 ± 10 56 ± 15
Liver 1051 ± 648 206 ± 210 121 ± 93 106 ± 78 88 ± 31
Gizzard 321 ± 119 70 ± 11 41 ± 11 53 ± 18 61 ± 17
Heart 303 ± 210 50 ± 12 35 ± 8 30 ± 6 43 ± 10
Skin 293 ± 76 63 ± 24 75 ± 55 25 ± 8 25 ± 7

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Correspondence:
Dr. Ralitsa Kyuchukova
Department of Food Hygiene and Control,
Veterinary Legislation and Management
Faculty of Veterinary Medicine
6000 Stara Zagora, Bulgaria
e-mail: ralitsa.kjuchukova@abv.bg

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