Multiple drug resistance is a global public health threat, especially in the developing countries. Integrons have been described as a molecular platform involved in the acquisition and dissemination of multi drug resistance gene in Gram-negative bacteria. Integrons allow bacteria to adapt and evolve rapidly through the stockpiling and expression of these genes. This study aimed to describe the multi-drug resistance and the spreading of resistance markers to other strain among diarrheagenic E. coli (DEC) and commensal E. coli strains isolated from animal effluents in Burkina Faso.
Strains of Escherichia coli have been isolated from fecal matter, slurries and manure samples, collected on 04 livestock markets in Ouagadougou, Burkina. Isolation of E. coli have been performed according to standards methods. The strains have been well characterized biochemically. The screening of diarrheagenic Escherichia coli (DEC) pathovars has been performed by multiplex PCR. We screened the DEC and non-diarrheagenic E. coli strains for resistance to 16 different antimicrobial agents including ampicillin, azithromycin, streptomycin, spectinomycin, kanamycin, trimethoprim + sulfonamides, tigecycline, gentamicin, amikacin, acid nalidixic, pefloxacin, ciprofloxacin, chloramphenicol tetracyclin, trimethoprim, and sulfonamides. PCR has been used to assay strains for the presence of the three classes integrons and the cassette gene carried by integron. The class 1 integrase (intI1) gene has been detected in DEC. The characterization of class 1 integrons has been further refined by conjugation assays, cloning and sequencing. The study of the transfer of genetic material by conjugation test shows that classe 1 integron is mobile and strains (ECD and non-DEC) are able to transfer plasmids to a recipient bacterium. The phenotypes of resistance observed for each trans-conjugate show that resistance markers were transferred from theses strain to a recipient.
Results show that pathogens (DEC) and antimicrobial resistance markers can be spread through the exchange of genetic materials with d other bacteria in the environment by livestock effluents in Ouagadougou, Burkina Faso.
Keywords: diarrheagenic E. coli (DEC), Livestock effluent, Antibiotic resistance, Intégrons, Transposon Tn21, Conjugation, dfrA14.