Abstract:
Sewage water (SW) and fresh livestock faeces: Chicken (ChNF), Sheep (SF), and Cattle (CF) were taken randomly from
the farm of the National University of Lesotho aseptically during the 2012 academic year. Twenty ml of sewage water or
20 grams of fresh animal faeces was dissolved in 80 ml of sterilized Ringer’s solution and serially diluted. A 0.1 ml of
sample suspension at 10-4 dilution was spread plated on Nutrient Agar (NA) and Eosine Methyl Blue (EMB) and plates
were incubated for 24-48h at 24 and 37°C, respectively. A disc diffusion method was used to test the reaction of selected
strains of Enterobacteriaceae to nine antibiotics. In total, 24 strains under Enterobacteriaceae were isolated from the
respective sources and the number of each that were Escherichia coli, as confirmed by the biochemical tests were: SW
(7 and 3); ChNF (5 and 3); SF (8 and 6) and CF (4 and 2). Thirteen E. coli strains fermented lactose and were Catalase
positive, while only one E. coli strain from SW was non-lactose fermenter and Catalase negative. The lethal potencies, as
number of isolates sensitive to the 9 antibiotics, ranked as: Colistin = Amikacin (24/24) > Kanamycin (23/24) >
Chloramphenicol (22/24) > Cefotaxime (21/24) > Sulphafurazole (7/24) > Methicillin (1/24) > Penicillin G = Rifampicin
(0/24). Sensitivity of the E. coli strains ranked as follows, Colistin = Amikacin = Kanamycin (14/14) > Chloramphenicol
(13/14) > Cefotaxime (12/14) > Sulphafurazole (6/14) > Methicillin (1/14) > Penicillin G = Rifampicin (0/14). This result
showed that the development of antibiotic resistant E. coli strains, which can pass through food chain to humans and
other organisms if stringent control measures are not taken. Strict quarantine procedures have to be applied to control
such potential health risks.
