Abstract:
The emergence of multidrug resistance (MDR) at an alarming rate among the microbial population
has been a public health concern. Globally, finding new antimicrobials that can kill multidrug resistant pathogens is thus a hot research area. Bacteria, specifically actinomycetes, are the most
prolific producers of antibiotics. Municipal waste has been a reservoir for multidrug resistance
pathogens due to the unwise disposal of leftover drugs from households. This study aimed to
identify multidrug resistance and antimicrobial-producing bacteria in a municipal solid waste soil
from dump site in Bahir Dar, Ethiopia. Thirty soil samples were randomly collected from the
municipal waste dump site in three rounds from February up to June, and analyzed by using SPSS
soffit ware version 26. Actinomycetes and other bacteria were isolated from these samples using the
spread plate method on starch casein, and nutrient agar medium respectively. The isolates were
screened for antimicrobial activity against at least one bacterial test strain by perpendicular
streaking. Isolates showing antimicrobial activity were further screened for better potential using an
agar well and disk diffusion method from an ethyl acetate crude extract of a bacterial culture.
Isolates showing both antimicrobial activity and drug resistance were identified using cultural
methods. Thirty nine bacterial isolates were subjected to different antibiotic disks to test antibiotic
susceptibility tests by the standard Kirby-Bauer's disc diffusion method. Regarding the drug
resistance profile, of a total of Thirty nine bacterial isolates, 38.4% were resistant; 21.74% of
isolates were intermediate and 39.86% of bacterial isolates were susceptible to selected antibiotic
disks and generally 46.15% of the bacterial isolates were multidrug resistance, from this the most
MDR isolates were S. aureus & E.coli. According to this study, for chloramphenicol and
ciprofloxacin most isolates were susceptible, but for amoxicillin and Nalidixic acid most bacterial
isolates were resistance. S.aureus and E.coli were shows the most resistant from the other isolate.
From a total of 70 actinomycetes, 20 (28.57%) showed antimicrobial activities with the inhibition
zone ranging from 0.0±0.0 up to 26.0±1.0 mm on average, in both agar well and disk diffusion
methods. Twenty effective actinomycetes were selected for MIC & MBC, and they have the value
of MIC and MBC between 250µg/ml to 500250µg/ml. Based on antibacterial activities, two
isolates were selected for the MIC and MBC tests against E.coli and S. aureus. From the present
study it could be conclude that sebatamite municipal waste site was good source of antibiotic
producing actinomycetes and it also contain most abundance of multidrug resistance. Further work
needs to identify all antibiotic producing and drug resistance microorganism up to species level by
using molecular characterization.
Key words: Antimicrobials, Actinomycetes, bacteria, drug resistance, waste dump sites