Acinetobacter spp.: resistência a antimicrobianos, genotipagem e dinâmica da colonização em CTI de um Hospital Universitário um ano de estudo

• Autor(a) principal: Barbosa, Beathriz Godoy Vilela
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14399
• topic: Acinetobacter baumannii; Oxacilinases; Antimicrobial resistance; Genotyping; Acinetobacter baumannii; Oxacilinases; Resistência a antimicrobianos; Genotipagem; CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA

The species of the genus Acinetobacter are common in the environment, but in recent decades have gained prominence as nosocomial pathogens, especially Acinetobacter baumannii and genospecies 3 and 13TU, which form the A. baumannii Complex and whose differentiation is only possible by the use of molecular methodologies. They are associated with different clinical presentations, mainly in patients hospitalized in intensive care units. Often exhibit resistance to a wide range of antimicrobials, including carbapenems. In these cases, treatment options may sometimes be restricted to polymyxin. This study aimed to evaluate the antimicrobial susceptibility, genetic diversity and colonization dynamics of Acinetobacter spp. isolated from patients hospitalized in the Intensive Care Unit of Hospital Universitário Pedro Ernesto in a year of study. During 2009, 76 strains of Acinetobacter spp. isolated from 34 patients were studied, most of them obtained from the respiratory tract (42.1%), followed by blood (19.7%). Of the total, 96.1% (73) were identified as A. baumannii by detection of the intrinsic gene blaOXA-51-like. All strains of A. baumannii were OXA-23 carbapenemase producers and showed a multiresistant profile, whereas the three non-baumannii species were susceptible to all antimicrobials tested. There were no amplification products for the genes blaOXA-24-like, blaOXA-58-like and blaOXA-143 by multiplex PCR. The islates showed resistance rates greater than 70% for eight of eleven antimicrobials: piperacillin-tazobactam, ceftazidime, cefotaxime, cefepime, amikacin, ciprofloxacin, imipenem and meropenem. The drug with the highest activity in vitro was polymyxin B. Four strains were resistant with MICs determined by E-test® ranging from 6 g/mL to 32 g/mL. A great genetic diversity was observed among the isolates, with ten clonal groups identified by PFGE. The clonal group B was prevalent and persistent in the unit, represented by 32 (42.1%) isolates. This was the same clone described as the most frequent in Rio de Janeiro in a previous study. The clone associated with an outbreak in the same institution between 2007 and 2008 was found in only seven (9.2%) isolates, having been replaced by genotype B. A prospective analysis of patients who were admitted for at least one month showed cases of clonal substitution after antimicrobial therapy, indicating the existence of environmental reservoir of circulating genotypes. Respiratory tract colonization by A. baumannii was quite common, but there were also cases of replacement of a non-baumannii species by A.baumannii, and bloodstream infection by a genotype different from that responsible for colonization. The presence of polymyxin-resistant strains is worrisome as it represents a threat to the therapy with this drug. The existence of a multiresistant clone widespread in Rio de Janeiro, possibly due to the transfer of patients and to sharing of common healthcare staff, points out the need to adopt more effective infection control measures in order to reduce the morbidity and mortality. In addition, the identification of epidemic strains environmental dispersion sources seems essential to ensure the efficiency of other outbreaks contention measures