Abstract:

Strains of Shiga toxigenic Escherichia coli are some of the milk-borne zoonotic pathogens
that globally cause sickness to millions of people each year. While Shiga-toxigenic
Escherichia coli has generally been isolated in the environment, cattle and human faecal
samples in Uganda, no study has specifically isolated these pathogens from bovine milk in
the country. This study aimed at isolation and characterization of Shiga toxigenic strains,
quantification and determination of antibiotic sensitivity of E.coli isolates from milk from
Mityana district. The amount of E. coli in the 200 collected samples was quantified based on
the number of colony forming units (CFUs) per ImL of the sample. Antibiotic sensitivity was
assessed using the Bauer-Kirby disc diffusion method. Up to six Shiga toxigenic field strains
were isolated and characterized by a multiplex PCR. The average CFUs/mL of milk was 1.68
x 105. Of the Eighty (80) E.coli isolates included six STEC and 74 non-STEC strains. Among
the six STEC isolates, four had all the three genes (slxi.Stxiancl EHEC-hly), while the other 2
isolates had either Shiga toxin i (S7.v/) and Shiga toxin 2 (.Etxi) or Six/ and Enteroheamolysin
(EHEC-hly). All the STEC (6) and non-STEC (74) isolates were 100% susceptible to
Ciprofloxacin and resistant to and Cioxacillin. Shiga toxigenic E. coli occurs in milk from
Mityana district, presenting a risk of human infection if milk is consumed raw.