No abstract

We read with great interest C. S. Antonio et al.'s letter describing the high prevalence of Acinetobacter baumannii carrying bla in Brazilian hospitals (1). Recently, we carried out a similar study, and although the bla OXA-143 gene was identified, its frequency was lower than that reported by Antonio et al. (1).During 2008, a total of 803 Gram-negative bacillus isolates, 1 isolate per patient, were collected from 17 private hospitals located in eight cities from four distinct geographic Brazilian regions. Among them, 91 (11.3%) were A. baumannii isolates that were recovered mainly from the respiratory tract (70.3%) and bloodstream (24.2%). Susceptibility testing was performed by CLSI broth microdilution (3). The detection of metallo-␤-lactamase (M␤L)-and carbapenem-hydrolyzing class D ␤-lactamase (CHDL)-encoding genes was performed by multiplex PCR (5, 7, 9) and confirmed by sequencing. The presence of the insertion sequence ISAba1 upstream of the CHDL-encoding genes was also investigated. Genetic relatedness among CHDL-producing A. baumannii isolates, including the first OXA-23-producing A. baumannii clone isolated in Brazil (4), was evaluated by pulsed-field gel electrophoresis (PFGE).A total of 83/91 (91.2%) isolates were resistant to carbapenems. We also observed low rates of susceptibility to amikacin (18.7%), ceftazidime (12.1%), cefepime (8.8%), piperacillin-tazobactam (3.3%), and ciprofloxacin (3.3%). In contrast, most A. baumannii isolates were susceptible to polymyxin B (MIC 90 , 1 g/ml; 97.8% of the isolates were susceptible).M␤L-encoding genes were not identified in our study, as was also reported by Antonio et al. (1). However, we identified the bla OXA-23 gene in carbapenem-resistant isolates more frequently than in the former study (83.5% versus 41.7%). The bla OXA-23 gene was found in all carbapenem-resistant isolates from the cities of Belo Horizonte, Blumenau, Curitiba, and São Luís, followed by Rio de Janeiro (93.7%), Porto Alegre (80.0%), and São Paulo (69.0%). These results are in accordance with previous local reports (2, 4, 6) that emphasize that this gene is widespread in our country. The ISAba1 element was positioned upstream of bla in all isolates, whereas no insertion sequence was observed upstream of bla . Although A. baumannii carrying bla OXA-58 and bla OXA-72 had recently been described in Brazil (1,8), no isolates carrying these variants were found in our study.Nine distinct PFGE clones were identified among the 76 OXA-23-producing A. baumannii isolates. The predominance of a single clone (clone A [36.8% of the isolates]) was observed in isolates collected from six distinct Brazilian cities. This clone exhibited a PFGE profile similar to that of the first Brazilian clone producer of OXA-23 (4). A. baumannii belonging to clones B (17.1%) and D (9.2%) were also identified in isolates collected from distinct cities, while other genotypes were identified in specific locations.While

pela oportunidade, pelo conhecimento e por sua compreensão nos momentos de dificuldades.Ao Prof. Dr. Nilton Erbet Lincopan Huenuman, por ter transmitido gentilmente informações primordiais para o desenvolvimento deste trabalho e pela importante ajuda fornecida, mesmo nos momentos em que se encontrava impossibilitado com suas ocupações. À banca examinadora de qualificação, composta pelo Prof. Dr. AntonioCarlos Pignatari e pela Profa. Dra. Silvia Figueiredo Costa, pelas valiosas sugestões.Às minhas colegas de laboratório Patrícia, Lilian, Lara, Mônica, Mariama pela troca de conhecimentos e companheirismo e à Franciele e Ketrin pela ajuda na execução dos experimentos.Ao meu querido pai Sarquis pela lição de vida.À minha amada mãe Conceição pela dedicação, pelos sábios conselhos que me são dados diariamente e pelo amor incondicional. Aos meus irmãos, cunhados e sobrinhos pelo incentivo.Ao meu amor pelo apoio de sempre.