Genotypic diversity of imipenem resistant isolates of Acinetobacter baumannii in Spain.
OBJECTIVE
To investigate relevant clinical and microbiological features of Acinetobacter baumannii in Spanish hospitals and to establish the genotypic diversity of imipenem resistant isolates.


METHODS
Seven Spanish hospitals collected 354 consecutive isolates that were subjected to antimicrobial susceptibility testing by standard methods. Further genetic analysis was determined by PFGE in a subset of 135 isolates from three hospitals selected because each of them presented high-, medium-, and low imipenem resistance rates.


RESULTS
Most isolates were from males (61.9%), age >65 years (52.3%), admitted to ICU (35.6%), and isolated from the respiratory tract (31.1%). Rates of carbapenem- and sulbactam resistance were 44.9% and 39.9%, respectively. Colistin was active against multiresistant isolates. Rates of imipenem resistance varied according to individual hospital (average: 43.8%; range: 13.5%-85.0%), medical department (more prevalent in ICU), and clinical sample (higher in isolates from the respiratory tract). Of the 135 isolates studied by PFGE (64 of them imipenem-resistant), 115 (85.1%) were distributed among 14 clusters and 20 were unrelated. Of the imipenem-resistant isolates, 45 (70.3%) belonged to six clusters that also had imipenem- susceptible isolates; 14 constituted four exclusive clusters, and five were unrelated.


CONCLUSIONS
Acquisition of imipenem resistance in A. baumannii is likely due to both clonal and non-clonal dissemination; resistance rates strongly vary between different hospitals and even between different hospital departments.
Oteo
Jesús
J
Laboratorio de Antibióticos, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
García-Estébanez
Carmen
C
Migueláñez
Silvia
S
Campos
José
J
Martí
Sara
S
Vila
Jordi
J
Domínguez
Maria Angeles
MA
Docobo
Fernando
F
Larrosa
Nieves
N
Pascual
Alvaro
A
Pintado
Vicente
V
Coll
Pere
P
D000151:Acinetobacter Infections / Q000453:epidemiology*; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics*; D004351:Drug Resistance / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D014644:Genetic Variation; D006761:Hospitals; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017720:Molecular Epidemiology; D011446:Prospective Studies; D013030:Spain
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D015378:Imipenem