OXYTETRACYCLINE RESIDUES AND ANTIMICROBIAL DRUG RESISTANT ESCHERICHIA COLI IN RAW MILK FROM DAIRY FARMS IN KANO STATE, NIGERIA
OXYTETRACYCLINE RESIDUES AND ANTIMICROBIAL DRUG RESISTANT ESCHERICHIA COLI IN RAW MILK FROM DAIRY FARMS IN KANO STATE, NIGERIA
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Date
2014-09
Authors
YUSUF, Muhammad Sanusi
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Abstract
The use of veterinary drugs in food animals may result in trace quantities of the drugs or
their metabolites as residues in food. The aim of this study was to determine the
occurrence and concurrence of oxytetracycline residues and antimicrobial drug resistant
Escherichia coli in raw milk from some commercial dairy farms in Kano State.
Eighteen (18%) percent of the total registered farms (54 farms) in the State were
sampled using a purposive sampling technique. Twenty five percent (25%) occurrence
of antimicrobial residues in milk was observed, of which 93.7% of them were
tetracyclines. The distribution of antimicrobial residues in milk based on farm type
indicated antimicrobial residue was highest in the conventional farms. There was a
statistically significant (P<0.05) association in the premitest results between detection of
antimicrobial residues and the type of farm. The conventional farms had 36.51%
(46/126) antimicrobial residues in which 89.13% were tetracycline residues while the
cooperatives had 17.65% (33/187) antimicrobial residues of which 100% were
tetracycline residues. There was a statistically significant association (p<0.05) between
detection of antimicrobial residue and the breeds of animal sampled. Occurrence of
antimicrobial and tetracycline residues was highest further away from the metropolis
with occurrence of 30.63% and 100%, respectively, compared to other locations. Out of
70 milk samples that were collected from within the metropolis, 19 (27.14%) had
antimicrobial residues of which 14 (73.68%) were tetracycline residues. Eleven
(13.25%) of the 83 samples collected from Local Governments Areas bordering Kano
metropolis contained antimicrobial residues of which 100% of them are tetracycline
residues. There was a statistically significant association (P< 0.05) in the distribution of residues between the different locations. Fifteen E. coli (4.8%) were isolated from the
313 milk samples collected and tested in which three (3) were from residue positive milk and twelve (12) were from residue negative milk. Out of the four moderately
resistant E. coli that were tested, 3 (75%) of them were from residue positive milk while
1 (25%) was from residue negative milk. Ten (90.91%) of the Multi-Drug resistant E.
coli were from residue negative milk samples. None of the E. coli isolates was resistant
to any of the quinolones tested, (nalidixic acid and ciprofloxacin) 13.3% were resistant
to chloramphenicol (a synthetic antibiotic) and cefixime (a cephalosporin) while 33.3%
were resistant to amoxicillin+clavulanic acid (a synthetic penicillin) and co-trimoxazole
(a sulfa drug). About 26.7% and 40% of the isolates were resistant to gentamicin and
kanamycin (aminoglycosides), respectively, while resistance to tetracycline was 46.7%.
However, all of the isolates were resistant to Ampicillin (a synthetic penicillin). Result
from the PCR showed that one of the isolates was carrying tet M resistance gene while six (40%) others were carrying tet A resistance gene. This study revealed the
occurrence of antimicrobial residues in milk samples from commercial dairy in Kano
State, Nigeria. The study further revealed that the E. coli isolates carry tet resistant
genes. It is recommended that farmers should avoid the indiscriminate use of antibiotics
in production, and they should observe drug withdrawal periods before milking their
cows.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD
OF DEGREE OF MASTER OF SCIENCE IN VETERINARY PUBLIC HEALTH
AND PREVENTIVE MEDICINE
DEPARTMENT OF VETERINARY PUBLIC HEALTH AND PREVENTIVE
MEDICINE,
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
OXYTETRACYCLINE RESIDUES,, ANTIMICROBIAL DRUG RESISTANT ESCHERICHIA COLI,, RAW MILK,, DAIRY FARMS,, KANO STATE,, NIGERIA