Impaired virulence and in vivo fitness of colistin-resistant Acinetobacter baumannii.
Rafael López-Rojas, Juan Domínguez-Herrera, Michael J McConnell, Fernando Docobo-Peréz, Younes Smani, María Fernández-Reyes, Luis Rivas, Jerónimo Pachón
Author Information
Rafael López-Rojas: Servicio de Enfermedades Infecciosas, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas/Universidad de Seville, Sevilla, Spain. rlopezrojas@hotmail.com
Acinetobacter baumannii (American Type Culture Collection strain 19606) acquires mutations in the pmrB gene during the in vitro development of resistance to colistin. The colistin-resistant strain has lower affinity for colistin, reduced in vivo fitness (competition index, .016), and decreased virulence, both in terms of mortality (0% lethal dose, 6.9 vs 4.9 log colony-forming units) and survival in a mouse model of peritoneal sepsis. These results may explain the low incidence and dissemination of colistin resistance in A. baumannii in clinical settings.
