Poster communication in Med-Vet-Net Association International Scientific Conference 2013 (One health, one medicine: sharing challenges for combating zoonoses)

June 24^th, 2013

Ovejero CM., Hidalgo L., Gutierrez B., Carrilero L., Santos-Lopez A., Thomas-Lopez D., Hoefer A., Santurde G., Martin-Espada C. and Gonzalez-Zorn B.

Tigecycline is the first of a new tetracycline class, the glycylcyclines. Its use is restricted to humans in hospitals for the treatment of complicated infections caused by resistant microbes. To date, the emergence of human isolates resistant to tigecycline has been limited. In Klebsiella pneumoniae the sole tigecycline resistance mechanism is associated with over-expression of the RND-like efflux pump AcrAB-TolC. The aim of this study was to characterise
these interesting isolates. PFGE showed that the clinical isolates were not clonal and they were typed using MLST. The isolates were identified as ST11 and ST147, both highly successful human K. pneumoniae lineages. In both strains the resistance to tigecycline (MIC > 4 μg/ml) reverted in presence of PAbetaN, a non-specific efflux pump inhibitor, showing that an efflux pump was involved in the resistance of the isolates. Sequencing, cloning and expression analysis showed that none of the efflux pumps involved in tetracycline or tigecycline resistance in Enterobacteriaceae to date was responsible for the tigecycline phenotype. This study describes for the first time the identification of two human internationally successful clones resistant to tigecycline isolated from animals, which reveals new ways of spreading for bacteria resistant to these last resort antibiotics. Our results suggest that resistance to
these molecules in Klebsiella is mediated by a new efflux mechanism, posing new and intriguing questions about the origin of tigecycline resistance in these isolates

	Servicio de Zoonosis de Transmisión Alimentaria y Resistencia a Antimicrobianos (ZTA). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).
	Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM).