The clinical problems of bacterial resistance to the new quinolones.

Clinical problems of bacterial resistance to the new fluoroquinolones are emerging as their use increases. Emergence of resistant strains has been observed in various types of infections, especially of the respiratory tract. Only limited studies, however, deal with strains isolated from clinical specimens. The identity between the original strain and the resistant variant is rarely proved. Resistance to quinolones can be due to a modification in DNA gyrase or to an alteration in outer membrane permeability (pleiotropic resistance). Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa have been recognized as species at risk of developing such resistance. Strategies to minimize the emergence of resistance are discussed.