Identifying Metal Resistance Genes in Staphylococcus Species Isolated from Wastewater and Streams Receiving Treated Effluent

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Environmental Engineering Science


Staphylococcus aureus and other staphylococci share mobile genetic elements that code for resistance to antibiotics and metals, allowing them to survive outside of their hosts in the environment, and become less sensitive to environmental factors and more resistant to antimicrobial agents. This study investigated the presence of select metal resistance genes (MRGs) originating from S. aureus and other staphylococci utilizing whole genomic sequencing and BlastN analysis of isolate genetic sequences obtained by selective enrichment of sewage-impacted samples over a 2-year period. Results from 26 isolate sequences recovered from 2 wastewater treatment plants, and creek sediments upstream and downstream, showed that MRGs carried in treatment plant influent S. aureus isolates were present in effluent Staphylococcus warneri isolates. The same MRGs were found in Enterococcus faecalis isolates recovered from the receiving creek sediments downstream of the plant effluent. The presence of MRGs specific to Staphylococcus delphini was identified in S. warneri, S. aureus, and E. faecalis isolates, indicative of horizontal gene transfer. This study has identified the potential role of coagulase-negative S. warneri in supporting the environmental spread of MRGs from coagulase-positive staphylococcus species present in sewage influent to bacteria in the receiving stream sediments, and highlights the need to control the spread of resistance genes of S. aureus by increasing treatment effectiveness for removing gram-positive bacteria and transference vectors.


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