Antimicrobial Resistance of Bacteria Associated with Raw Milk Contaminated by Chemical Preservatives

This paper had been presented for promotion at the university of Khartoum. To get the full text please contact the other at Ibtisammohamed@hotmail.comThis study was carried out on two hundred and forty raw milk samples collected randomly from farms and sales points in Khartoum State. One-hundred and twenty milk samples were collected during each summer and winter from the same sources. The milk samples were examined for the presence of some chemical preservative and isolation and identification of microorganisms from antibiotic contaminated milk. Moreover susceptibility of isolated bacteria towards some antibiotics was estimated. The chemical preservative residues examination included the detection of formaldehyde, hydrogen peroxide, boric acid, alkalinity of ash and detection of antibiotics and sulphonamide residue. In this study it was found that 5 (2.08 %) of the milk samples contained formaldehyde, moreover the result showed that the milk samples from sale points showed higher values compared to that from the farms. One sample (0.41%) was positive to the presence of hydrogen peroxide and 4 (1.6%) showed alkalinity of ash. Both were detected only in the milk samples collected from the farms. However all the milk samples examined contained no boric acid. On the other hand 30 (12.25 %) and 16 (6.66%) milk samples were contaminated with antibiotic and sulphonamide respectively, with the highest incidences in the milk samples collected from Khartoum compared to that collected from Omdurman and Khartoum North. The high incidence of antibiotic residues in the milk samples collected from venders might suggest the addition of antibiotics to the milk in order to prolong its shelf life. The isolated bacteria were identified as Staphylococcus aureus (8; 26.66%), Streptococcus pyogenes (4; 13.33%), Corynebacterium ovis (2; 6.66%), E. coli (5; 16.66%), Citrobacter Kasseri (6; 20%), Klebsiella aergenes (2; 6.66%), Pseudomonas aeruginosa (2; 6.66%) and Proteus mirabilis (3.33%). The isolated bacteria showed wide range of multiple resistances. The highest resistance was towards penicillin (63.33%), collxacillin (63.33%) clindamycin (56.66%) and ampicillin (56.66%), while Chloramphenicol (3.33%) showed the highest antimicrobial activity against the test organisms followed by pipercillin (13.33%) and gentamicin (20.00%