Escherichia coli as reservoir for macrolide resistance genes.

The plasmid-borne mph(A) gene that confers resistance to azithromycin and has recently emerged in Shigella sonnei is present in multidrug- and non-multidrug-resistant Escherichia coli isolates from 4 continents. Further spread of mph(A) to Shigella and Salmonella spp. may be expected.