Enrofloxacin is a fluoroquinolone antibiotic sold by the Bayer Corporation under the trade name Baytril. Enrofloxacin is currently FDA-approved for treatment of individual pets and domestic animals in the United States. In September 2005, the FDA withdrew approval of Baytril for use in water to treat flocks of poultry, as this practice was noted to promote the evolution of fluoroquinolone-resistant strains of the bacterium Campylobacter, a human pathogen. Fluoroquinolones such as ciprofloxacin are widely used in the treatment of human disease.
The aim of this study to investigate the possible developmental toxicity and teratogenicity of enrofloxacin on maternally-treated chick. Four equal fertile egg groups were utilized in the present study. The first (control) group was obtained from chickens that did not receive any antibacterial medication, while the second, third and fourth ones were collected at the first, seventh and tenth days following chicken treatment with enrofloxacin (10%) for 7 consecutive days, respectively. On embryonic days 6½ and 13, embryos were evaluated for mortality rate, fresh body weight, crown-rump length, anterior-posterior head length and various morphological and skeletal changes. The results revealed that 6½ and 13-day-old embryos of eggs obtained on both the first and seventh days following chicken treatment with enrofloxacin exhibited significantly (p
In commercial poultry farms the bacterial infection among laying chicken is common and usually needs rapid medication to avoid morbidity and mortality of the infected specimens. Therefore, huge quantities of antibiotics are used annually in poultry farming throughout the world, but the eventual fate of their residues and their potential damage to human health generally remains unknown. Enrofloxacin (1-Cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-Fluoro-1, 4-Dihydro-4-Oxo-3-Quinolonecarboxylic Acid) is a synthetic, broad spectrum antimicrobial medication used in poultry medicine, belonging to the fluoroquinolone group of antibiotics (Wolfson and Hopper, 1989). Several studies showed that enrofloxacin (Baytril 10%) oral solution was indicated for use in ducks, turkeys, broiler chickens, broiler breeders and pullets being reared as layers for diseases of the respiratory and alimentary tract of bacterial or mycoplasmal origin (Hafez et al., 1990; Kempf et al., 1995; Glisson, 1996; Barrow et al., 1998; McDermott et al., 2002; Randall et al., 2005; Luke et al., 2006; Garmyn et al., 2009a, b). In many countries it is being used as the routine choice to avoid infection and to treat almost any bacterial disease in poultry. Enrofloxacin inhibits cell proliferation, induces apoptosis and DNA fragmentation of canine tendon cells and chondrocytes in a dose and time-dependent manner (Lim et al., 2008). It also causes disruption of spermatogenesis in the testes of mice in the form of reduction of sperms motility and count as well as morphological abnormalities (Aral et al., 2007). It is well documented that enrofloxacin and its metabolite ciprofloxacin as well as other fluoroquinolones have a tendency to accumulate as residues in avian eggs and other edible tissues (Gorla et al., 1997; McReynolds et al., 2000; Yorke and Froc, 2000; Chu et al., 2002; Shim et al., 2003; Christodoulou et al., 2007; Cho et al., 2008; Zhao et al., 2009; Frenich et al., 2010). Embryo lethality and teratogenicity of fluoroquinolone antibacterials in rats and rabbits were previously suggested (Guzman et al., 2003; Kim et al., 2000, 2003-5). Also, reduction of scavenger wildlife populations and fatal embryo chondral damage associated with enrofloxacin and its metabolite ciprofloxacin in eggs of threatened avian scavengers were investigated by Lemus et al. (2008, 2009). However, in the literatures scanned, no study was found concerning the developmental toxicity and teratogenicity of enrofloxacin on the developing chick embryo. Therefore, the present study was undertaken to investigate the possible embryotoxicity and teratogenicity of enrofloxacin on embryonic days (EDs) 6½ and 13 of the developing chick of fertile eggs collected at the first, seventh and tenth days after the last day of chicken treatment, respectively. Accordingly, the results may help to find out an explanation of the low rate (≈53%) of fertile chicken eggs hatchability (following chickens treatment, against infectious diseases, with enrofloxacin) in a new commercial poultry farm in Al-Taif, KSA.
MATERIALS AND METHODS
Enrofloxacin (Baytril 10% oral solution) for dosing poultry was obtained from the National Veterinary Services Al-Taif, KSA. It is a clear aqueous oral solution containing as active ingredient 100 mg mL-1 enrofloxacin and 14 mg mL-1 benzyl alcohol as a preservative. In the poultry farm the enrofloxacin was added to the chicken’s drinking water (under the supervision of a licensed veterinarian) at a dose adjusted to give 10 mg kg-1 b.wt. of birds per day or equivalence, i.e., water at 50 ppm, continuously medicated water) for seven consecutive days.
The present study was carried out in the laboratory of Zoological Research, Biology Department, Faculty of Science, Taif University, KSA. This research was conducted from November-2009 to February-2010. A total of six hundred fertile white leghorn chicken eggs, each weighing about 70 g, were generously provided (in four successive groups, each 150 eggs) by the commercial poultry farm of Al-Taif, KSA. The first (control) group was obtained from chickens that did not receive any antibacterial medication; while the second, third and fourth ones were collected at the first, seventh and tenth days after the last day of chicken treatment with enrofloxacin, respectively.
Before incubation each egg group was stored in a refrigerator at 4°C for 24 h to allow egg contents to return to steady state after transport. The eggs were then transferred and maintained at 37.5°C in a full automatic egg incubator with full automatic control of humidity (relative 55-60%), egg turning, fan speed, ventilation and alarm until the desired stages of chick development (6½ and 13 day old embryos) were reached.
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