Milk is consumed by both young and old due to its nutritional benefit. However, it is a perfect medium for the growth of many microorganisms. This study was carried out to isolate and identify bacteria in milk powder sold in Ogun, Lagos and Oyo, Southwest, Nigeria. Three (3) samples each of five different brands were used for the analysis. 1ml of each milk sample homogenized with 10 ml of nutrient broth and incubated overnight at 37°C.  After incubation, the bacteria were plated on Mac-Conkey, EMB and Nutrient agar. The identified organisms were identified by partial sequencing of 16SrRNA genes. They were tested against  Cefuroxime (30 µg), Gentamicin (10 µg), Erythromycin (15 µg), Ofloxacin (5 µg), Augmentin (30 µg) ,  Ceftazidime (30 µg), Cefuroxime (30 µg), Acyclovir (1.3 µg), Cefotaxime (25 µg), Imipenem (10 µg),  Ofloxacin (5 µg), Nalidixic Acid (30 µg), Cefixime (5 µg), Ceftriaxone(45 µg),  Sulbactam (10 µg), Levofloxacin (5 µg),  Nitrofurantoin (300 µg), Ciprofloxacin (5 µg), Nitrofurantoin (300 µg), Azthromycin (15 µg). The result from the molecular test revealed the presence of five bacterial species: Pseudomonas aeruginosa, Bacillus cereus, Brevibacillus agri, Lysinibacillus sphaericus and Bacillus thuringiensis.  Pseudomonas aeruginosa was  sensitive to Gentamicin and Cefuroxime but more sensitive to Nitrofurantoin (80.0%). Brevibacillus agri (LATC3) show sensitivity to Gentamicin and Cefuroxime but more sensitive to gentamicin (55.00%). Bacillus cereus (LAKG2 and LAC2) shows sensitivity to Ofloxacin, Cefotaxime, Augmentin, Acyclovir, Levofloxacin but more sensitive to Ceftriaxone 60%. The presence of the bacteria shows the presence of some pathogenic organisms in the microbial populations despite pasteurization. This can occur as a result of poor storage of milk products by retailers or poor sanitization of equipment and facilities during production and packaging. Therefore, it is essential to monitor the microbial quality of pasteurized milk to ensure its safety and shelf life.

Keywords: Antibacterial sensitivity, Homogenized, Pasteurization, Pathogenic, Spoilage