The burden, antibiogram and pathogenicity of bacteria found in municipal waste dumpsites and on waste site workers in Benin City
AbstractMunicipal wastes may harbour microbial pathogens but the quantum and diseasecausing capacities of such organisms are rarely investigated. This study sought to establish the burden, antibiogram and pathogenicity of bacteria in 4 selected waste dumpsites and those found on hands and clothings of the respective waste dumpsite workers in Benin City. Swabs from hands and clothings of waste site workers and specimens of top soils and leacheates from waste dumpsites were obtained at monthly intervals for 12 months from 4 sites in Benin City (University of Benin, Costain Road, Government Reservation Area, and Benin Bye-pass). The samples were cultured on Blood, MacConkey and Griseofulvin nutrient agar plates
and incubated aerobically and anaerobically. Heterotrophic viable bacteria counts were determined for soil and leacheate specimens. The predominant bacterial isolates from the cultured plates were phenotypically characterized using standard methods. Antimicrobial disc susceptibility tests and pathogenicity tests were also carried out on the predominant isolates. Eleven Bacteria Genera were isolated from topsoils and leacheates. They were in the following order of predominance: Bacillus sp (18.20%) Staphylococcus sp (13.93%), Escherichia coli (12.72%), Proteus sp (12.12%), Streptococcus sp (12.12%), Klebsiella sp (9.70%), Pseudomonas sp (7.90%), Citrobacter sp (5.45%), Bacteroides sp (3.03%), Clostridium sp (2.42%), Serratia sp (2.42%). Bacterial isolates from the waste workers were essentially similar to those isolated from the dumpsites although the latter were more heavily colonized. The highest bacterial burden was recorded from the top soil samples at Benin Bye-pass dumpsite with a mean viable count of 2.0 x106+ 0.88 x106cfu/gm while the least was from the University of Benin dumpsite with mean count of 0.7x106+0.56x106cfu/gm.The antibiograms of the isolates revealed that the organisms were most susceptible to the fluroquinolones especially Ciprofloxacin (96.6%) and Pefloxacin (94.6%). They were least susceptible to Amoxacillin (51.7%) and Erythromycin (55.8%). All bacteria species isolated showed multiple drug resistance patterns with Serratia marcescens and Pseudomonas aeruginosa each exhibiting higher levels of multidrug resistance. A number of the isolates exhibited pathogenicity traits. Whereas 27.6% of them were positive for virulence gene, 24.3% were invasive while 17.2% were diarrheagenic. We conclude that municipal waste dumpsites and those working at such sites bear heavy burdens of potentially pathogenic multidrug resistant bacteria which may constitute major public health hazards, not only to the immediate communities but
also to the families of such site workers. The need to educate these waste workers on the use of appropriate protective materials and about the risks and hazards associated with their job are emphasized. Proper disposal and recycling of these wastes ought to be mandatory.