Enumeration and identification of gram negative bacteria present in soil underlying urban waste-sites in southwestern Nigeria

Samples of soils underlying wastes were collected from four sites representing four demographic regions of a medium sized town in southwestern Nigeria. Standard methods and reference strains of isolated bacteria were employed for identification. Evaluation of the enzymatic and biochemical reactions showed that all isolated and identified microbes were non-fermenting heterotrophic (HTB). For example, Klebsiella pnemuniae may be involved in wound infections, particularly following bowel surgery. Similarly Pseudomonas aeruginosa can produce serious nosocomial infections if it gains access to the body through wounds or intravenous lines. From the 15 culure plates, 88 colonies with various characteristics were enumerated. They differed in aspect of viscosity and color. The bacterial species were identified by percent positive reactions while oxidative and sugar fermentation tests revealed various characteristics among the isolated strains. All of the isolates were negative for citrate utilization, gelatin liquefaction, nitrate reduction, methyl red and Voges Proskaur, motility and hydrogen sulphate production. The quantity of HTB present in an area serves as an index of the general sanitary conditions of that area. The presence of a large number of HTB, in an ecological area may be considered a liability as it can enhance the spread of diseases and on a larger scale may enable epidemics to arise. Therefore, there is need for control of waste sites by recovery and regular germicidal sanitation.