Resistance To AntibodiesEfflux-mediated antibiotic resistance in Gram-positive bacteriaBellido, Juan Luis Muñoz*,†; Guirao, Genoveva Yagüe‡; Zufiaurre, Nieves Gutiérrez†; Manzanares, Angeles Alonso§Author Information *Department of Microbiology, Hospital Universitario de Salamanca, †Department of Preventive Medicine, Public Health and Medical Microbiology, University of Salamanca, Salamanca, ‡Department of Genetics and Microbiology, University of Murcia, Murcia, and §Unit of Microbiology, Hospital Virgen de la Concha, Zamora, Spain Address for correspondence: Dr J. L. Muñoz Bellido. Department of Microbiology. Hospital Universitario de Salamanca. Po de San Vicente s/n. 37007 Salamanca. Spain. Tel: +34 923 26 48 25. Fax: +34 923 26 22 61. E-mail: [email protected] Reviews in Medical Microbiology: January 2002 - Volume 13 - Issue 1 - p 1-13 Buy Abstract Efflux is a widely used mechanism of resistance to several toxic compounds, in both eukaryotic and prokaryotic cells, and it is a well-known mechanism of resistance to some antibiotics such as tetracyclines. Efflux-mediated resistance is being described increasingly for microorganisms in which, and antibiotics for which, it was previously unknown. In the 1990s efflux-mediated quinolone resistance was described in the important Gram-positive pathogens such as Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus agalactiae and enterococci. Efflux-mediated macrolide resistance mechanisms were described during recent years in pneumococci, group A Streptococcus pyogenes and other Gram-positive cocci. In fact, efflux is the main mechanism of resistance to macrolides in Streptococcus pyogenes in many areas. Efflux has also been described as an important mechanism of resistance to tetracyclines in Gram-positive bacteria. In some cases, the increase in the mimimum inhibitory concentration derived from efflux is modest, and its impact on clinical resistance is unclear. In other cases, efflux can lead to clinical resistance by itself, and seems to have some influence on the rate of emergence of further mechanisms leading to higher level resistance. © 2002 Lippincott Williams & Wilkins, Inc.