Anti-infective strategies of the future: is there room for species-specific antibacterial agents?

Broad-spectrum antibiotics, directed against conserved bacterial targets, are the mainstay of antibacterial therapy. Increasing resistance, however, demands new strategies. Over time a number of therapeutic concepts have evolved, starting out with the use of polyclonal antisera, which were rapidly replaced by the easier to use antibiotics. Other concepts, such as immunotherapy, radioimmunotherapy, anti-virulence agents, phage therapy and others are under evaluation and often limited in application. In the discovery process of new antibiotics in the pharmaceutical industry quite a number of new agents have emerged, which exhibit a surprisingly high degree of species-specificity. None of them has been considered for development so far. Some examples from the literature which show selectivity for Helicobacter pylori, Pseudomonas aeruginosa, Haemophilus influenzae, Staphylococcus aureus, anaerobes, and others, will be discussed here. It is postulated that there is a room for such agents in future antibacterial therapy, e.g. in difficult to treat infections caused by nonfermenters such as multiresistant P. aerugoinosa, Acinetobacter, Enterobacteriaceae, and S.aureus, including MRSA. Their application would include monotherapy as well as combination therapy with other antibiotics, anti-virulence agents or immunotherapy and these possibilities would greatly expand the current anti-infective armamentarium.