K pneumoniae

Twenty‐five microlitres of 2.5 × 10⁵ CFU of K. pneumoniae in 1× PBS (Thermo Scientific) were inoculated into wells of a 96‐well plate containing 75 μl of 100% pooled normal human serum (Sigma‐Aldrich). Control serum was inactivated by heating at 56°C for 30 min prior to incubation of bacteria. The plate was then incubated at 37°C. At 0, 1, 2 and 3 hr post inoculation, appropriate dilutions were plated on LB agar to enumerate surviving bacterial colony‐forming units (CFU).

Filtration of all water samples was done on arrival using the membrane filtration technique, as recommended by the American Public Health Association [16 ]. One hundred milliliters of water samples were passed through a vacuum pump filter device with a sterile filter membrane having a pore size of 0.45 m that contained microorganisms in this method. After filtration, the bacteria-containing membranes were spread over Oxoid’s Eosin Methylene Blue (EMB) Agar and incubated at 37°C for 24 h.
Tomato samples were sterilized on the surface by immersing them in a 70% ethanol solution and drying them. Alegbeleye Guo et al. [17 ] indicated that the tomatoes were sliced into stem scar and pulp using a sterile knife. Each sample was stomached in a sterile stomacher bag with 9 mL of sterile 0.1% peptone water for 2 min. One milliliter of the sample was mixed with 9 mL of tryptic soya broth (TSB) and incubated at 37°C for 24 h.
After that, a loop of tryptic soya enrichment was streaked onto EMB agar, which was then incubated at 37°C for another 24 h. Suspected K. pneumoniae colonies were sub-cultured onto nutrient agar plates and provisionally identified using morphological characteristics, Gram’s stain, and biochemical characteristics [18 ]. The RapID ONE test was used to identify K. pneumoniae (Oxoid-remel USA) biochemically.