One way in which drug-resistant bacteria may be attacked is to screen new series of candidate compounds. Quaternary quinoline compounds and dyes were studied by Carl Browning (1887-1972) and Julius Cohen (1859-1935). A remarkable part of Browning and Cohen's work was the early development of structure-activity relationships for their series of compounds. Thus cationic species were found generally to be more effective antibacterials than neutrals or anionics, and the testing of partial or deconstructed active molecules was also carried out. Much of this work underpinned the fuller understanding of e.g. aminoacridine action developed by Adrien Albert (1907-1989), himself also a collaborator of Browning. Analysis of the activity of a range of compounds developed by Browning and Cohen suggests that these might again be examined as topical antimicrobials in the fight against methicillin-resistant S. aureus (MRSA) and other resistant bacteria.