Isolation and Identification of Enteric Bacteria from Raw Cow Milk from Carysburg Slaughter House in New Island Community, Carysburg, Montserrado County Liberia

Abstract

Raw cow milk from informal dairy systems in developing countries, including Liberia, is frequently contaminated with enteric bacteria, posing significant public health risks due to widespread consumption without pasteurization. This study investigated microbial safety of raw cow milk produced at Carysburg Slaughter House, Montserrado County, Liberia. Hence, isolating, identifying, and characterizing enteric bacteria from raw cow milk and determine their antibiotic susceptibility profiles. Four raw milk samples were collected aseptically from individual cows at Carysburg Slaughter House in 2025. Samples were cultured on MacConkey agar, HiCrome agar, and nutrient agar. Presumptive enteric isolates were identified using Gram staining, standard biochemical tests (Kligler Iron Agar, citrate, motility indole-ornithine, urea), and colony characteristics. Antibiotic susceptibility testing was performed using the Kirby-Bauer disk diffusion method against gentamicin (10 µg), ciprofloxacin (5 µg), amoxicillin (30 µg), ceftriaxone (30 µg), and chloramphenicol (30 µg), with results interpreted according to CLSI guidelines. Results: Two of the four milk samples (50%) yielded enteric bacteria. The isolates were identified as Citrobacter freundii and Salmonella enterica serovar Typhi. Both isolates were resistant to amoxicillin (100%) but fully susceptible to gentamicin, ciprofloxacin, ceftriaxone, and chloramphenicol. No multidrug resistance was observed. Raw milk from Carysburg Slaughter House is contaminated with potentially pathogenic enteric bacteria, including the alarming presence of Salmonella Typhi, indicating severe hygienic deficiencies and human fecal contamination. Immediate interventions—improved milking hygiene, routine milk testing, and promotion of pasteurization—are urgently needed to prevent foodborne outbreaks in this community.