Outbreak of Acinetobacter baumannii producing OXA-66 in a Spanish hospital: epidemiology and study of patient movements

Abstract

We describe an outbreak of multidrug-resistant Acinetobacter baumannii producing OXA-66 carbapenemase and resistant to imipenem. We analyze the relationship between the spread of this strain and patient movements within the hospital. Thirty-one isolates of A. baumannii recovered from December 21, 2006, to February 18, 2007, were studied. Enterobacterial repetitive intergenic consensus PCR and randomly amplified polymorphic DNA genotyping methods were used to define clusters of clonally related isolates. Pulsed-field gel electrophoresis was used to confirm the results and to check the maintenance of the epidemic strain over the following year. Antibiotic susceptibility testing was performed by microdilution and E-test. The isolates were screened by PCR analysis with primers specific for carbapenemase genes. With the exception of colistin (0%) there were no antibiotics with good activity against these isolates. The epidemiology study revealed that the same strain was responsible for all the infections. This strain appeared to carry the bla(OXA-66) gene. ISAba1 was present upstream the oxacillinase gene. The clone responsible for the outbreak is still present in hospital.