TITLE:
Occurrence of tetracycline residues and antimicrobial resistance in gram negative bacteria isolates from cattle farms in Spain
AUTHORS:
Matilde Carballo, Fernando Esperón, Carlos Sacristán, Miguel González, Belén Vázquez, Sonia Aguayo, Ana de la Torre
KEYWORDS:
Antimicrobial Resistance; Gram Negative Bacteria; Cattle Manure; Tetracycline
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.4 No.2A,
February
28,
2013
ABSTRACT: The
usage of antibiotics in animal husbandry has dramatically increased the
concentration of antibiotic residues and has promoted the development and abundance
of antibiotic resistance in manure. When it is spread onto agricultural land,
both residues of antibiotics and bacteria carrying antibiotic resistance genes
may be introduced into the environment. In this research, we isolated resistant
gram negative bacteria from manure produced in two dairy and two beef cattle
farms, located in Madrid (Spain), to determine their resistance to seventeen
representative antibiotics commonly used in veterinary therapy. A total of 63
isolates were used to assess the overall bacterial antimicrobial resistance
on cattle manure samples. Predominant species were Escherichia coli and Comamonas
testosteroni accounting for 25% and 19.6% of the total, respectively. The
most found antimicrobial resistances in gram-negative bacteria were to tetracycline (66.7%), sulphamethoxazole (55.6%), ampicillin (52.4%), cephalothin
(46.0%), chloramphenicol (44.4%), nalidixic acid (39.7%) and trimethroprim- sulphamethoxazole
(33.3%). The mean of resistance and the percentage of multi-resistant bacteria
in beef farms were higher and statistically significant when compared to dairy
farms which is opposite from the findings of the previous studies. The presence of three tetracyclines in all manure
samples was also examined with stable recoveries (76% - 82%) and high
sensitivity (limit of quantification 0.015 - 0.03 μg/kg). The concentrations of
tetracyclines detected (