title: Clonal diversity of nosocomial epidemic Acinetobacter baumannii strains isolated in Spain.
abstract: Acinetobacter baumannii is one of the major pathogens involved in nosocomial outbreaks. The clonal diversity of 729 epidemic strains isolated from 19 Spanish hospitals (mainly from intensive care units) was analyzed over an 11-year period. Pulsed-field gel electrophoresis (PFGE) identified 58 PFGE types that were subjected to susceptibility testing, rpoB gene sequencing, and multilocus sequence typing (MLST). All PFGE types were multidrug resistant; colistin was the only agent to which all pathogens were susceptible. The 58 PFGE types were grouped into 16 clones based on their genetic similarity (cutoff of 80%). These clones were distributed into one major cluster (cluster D), three medium clusters (clusters A, B, and C), and three minor clusters (clusters E, F, and G). The rpoB gene sequencing and MLST results reflected a clonal distribution, in agreement with the PFGE results. The MLST sequence types (STs) (and their percent distributions) were as follows: ST-2 (47.5%), ST-3 (5.1%), ST-15 (1.7%), ST-32 (1.7%), ST-79 (13.6%), ST-80 (20.3%), and ST-81 (10.2%). ST-79, ST-80, and ST-81 and the alleles cpn60-26 and recA29 are described for the first time. International clones I, II, and III were represented by ST-81, ST-2, and ST-3, respectively. ST-79 and ST-80 could be novel emerging clones. This work confirms PFGE and MLST to be complementary tools in clonality studies. Here PFGE was able to demonstrate the monoclonal pattern of most outbreaks, the inter- and intrahospital transmission of bacteria, and their endemic persistence in some wards. MLST allowed the temporal evolution and spatial distribution of Spanish clones to be monitored and permitted international comparisons to be made.
authors.affiliation: Laboratorio de Taxonomía, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain. pvillalon@isciii.es
authors.forename: Pilar
authors.initials: P
authors.lastname: Villalón
authors.forename: Sylvia
authors.initials: S
authors.lastname: Valdezate
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Medina-Pascual
authors.forename: Virginia
authors.initials: V
authors.lastname: Rubio
authors.forename: Ana
authors.initials: A
authors.lastname: Vindel
authors.forename: Juan A
authors.initials: JA
authors.lastname: Saez-Nieto
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D058889:Molecular Typing; D058885:Multilocus Sequence Typing; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D013030:Spain / Q000453:epidemiology
chemical_list: D004269:DNA, Bacterial; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit