Isolation and characterization of bacteria flora from dumpsites in Benin City metropolis, southern Nigeria.

Abstract

BACKGROUND: The waste dumps are indiscriminately placed at common sites in developing countries. It has been reported that over 5.2 million people, that includes 4 million children, die each year from waste related diseases. Waste is any substance, solution mixture or particle for which no direct use is envisaged but which is transported for reprocessing, dumping, elimination by incineration or other methods of disposal.
Aim: The study is to isolate, identify and characterize bacteria from different dump sites in Benin City Metropolis, Edo State, Nigeria.
Materials and Methods: Soil samples were collected from the various dumpsites and the adjacent control sites in a sterile universal container. The bacterial load count for the various dumpsites and the adjacent control sites was counted using mise and misra serial dilution method. Aerobic and facultative anaerobic bacteria were isolated from dump site samples using five different culture media. Phenotypic test was assayed using double disk method to check for Extended Spectrumβ-lactamase (ESBL) and metallo-β-lactamase enzyme among the Gram negative bacterial isolates.
Results: The following bacteria in decreasing order of prevalence were isolated from the various dumpsites Bacillus spp (30.01%),Klebsiella spp (24.27%), Staphylococcus aureus(12.62%),Coagulate Negative S.aureus (CONS)(10.68%),Pseudomonas spp (6.79), E. coli (4.85%), Alcaligenes spp (4.85%) and Proteus spp(2.91%). Also the following bacteria in decreasing order of prevalence were isolated from the various adjacent control sites, Bacillus spp (66.67%),Klebsiella spp(9.52%), Coagulate Negative S.aureus (CONS) (7.14%) Pseudomonas spp(4.76%), Staphylococcus aureus (2.38%), and Proteus spp (2.38%). Antibiotic susceptibility tests on isolates were performed using standard disc diffusion method. Overall, Ciprofloxacin, Imipenem and Pefloxacin were the most effective agents on the isolates obtained from the various dumpsites. E. coli isolated from the various dumpsites 164 showed strong resistance to almost all antimicrobial agents employed. More so Proteus vulgaris isolated from Oregbeni market dumpsite showed resistance to almost all antimicrobial agent employed. Klebsiella aerogenes, Klebsiella oxytoca and Pseudomonas aeruginosa were observed to be positive to metallo- β-lactamase test. However, other bacterial isolates were observed to be negative for ESBL test. Nonethelessbacteria isolates could cause opportunistic infections which may cause more harm to immune-deficient individuals in the clinic, and in the residences.
Conclusion: Waste managers and scavengers should endeavour to put on protective clothing, face mask and hand gloves while handling waste. Also proper sorting of waste material should be done prior to disposal in the general dumpsites.

Key words:Waste, Dumpsites, ESBL, β-Lactamase, Coagulase Negative Staphylococcus
(CONS).