ABSTRACT
Landfill sites are potential risks for the environment, as microbes and toxic substances may find their way into water sources and, via agriculture or direct contact with humans, re-enter the human food chain. The Yatta landfill site, which serves the Hebron and Bethlehem directorates is not lined, which constitutes a special hazard because of the possibility of leachates entering the environment. Nevertheless, its use continues while a new site is being prepared at al Menya (World Bank 2009).
The municipal solid waste coming into the Yatta landfill site was assessed for possibly harmful microbes, which might pose an environmental health risk. Furthermore, the hypothesis that this microbial examination of the municipal solid waste arriving at the site could serve a useful function as an indicator of public health was also tested. To that end, samples of food, human feces, organic matter, toilet paper and cardboard in the municipal solid waste of nine separate waste skips, from a representative selection of villages and towns that arrived at the site over a two week period were examined for bacterial contamination.
The nine towns and villages from which samples were obtained were grouped into three different socioeconomic metrics, and “most probable number” (MPN) data on Salmonella sp and “colony forming units (CFU)” data for E.coli and total coliforms in the various categories of solid waste were calculated from each of the nine town and village samplings. It was found that the highest bacterial loads depend on the source. CFU/g for E.coli and coliforms from feces reached the order of 108 with on average a single log reduction for food, while MPN for Salmonella of 104 - 105 were found in food waste from 8 of the 9 sites.
A small, random sample of the isolated bacteria were tested for antibiotic susceptibility, and only 50% were clearly susceptible for ampicillin, while all were fully susceptible to nitrofurantoin and 3 third generation cephalosporins, with intermediate sensitivities for combined amoxicillin and clavulanic acid, ciprofloxacin, and cefoxitin.
The Salmonella test results were confirmed by microbiology and molecular techniques. Microbial techniques were used to isolate Salmonella positive clones on XLD plates from 11 different samples of food and feces from 6 distinct regions of Hebron and Bethlehem. A portion of the invA gene of each of these was amplified by PCR and sequenced. All the sequences were variants of two serovars: 9 were Salmonella enterica serovar Heidelberg and two were serovar Newport. Both of these serovars, and especially Heidelberg, have been implicated as important causes of public health concern throughout the world.