Characterization and molecular epidemiology of carbapenem resistant and sensitive Acinetobacter baumannii isolates from three hospitals in Porto Alegre

Acinetobacter baumannii é uma bactéria de grande importância clínica, sendo causa de diversas infecções nosocomiais, incluindo bacteremias, pneumonia e meningites. O tratamento dessas infecções tem se tornado crítico em função do surgimento de isolados resistentes aos antimicrobianos mais utilizados na prática clínica e também aos carbapenêmicos, tendo como melhor alternativa terapêutica, nestes casos, a polimixina B. O presente estudo avaliou o perfil de susceptibilidade a diferentes classes de antimicrobianos, em especial aos carbapenêmicos e polimixina B, em 132 isolados de Acinetobacter spp., isolados no período de março a dezembro de 2011 em três hospitais de Porto Alegre. A susceptibilidade foi avaliada pela determinação da Concentração Inibitória Mínima (CIM) através da técnica de microdiluição em caldo de acordo com os critérios do Clinical and Laboratory Standards Institute (CLSI), para os seguintes antimicrobianos: ampicilina/sulbactama, imipenem, meropenem, cefepima, ceftazidima, ciprofloxacina, polimixina B e tigeciclina. Adicionalmente buscou-se avaliar os mecanismos de resistência aos carbapenêmicos através da pesquisa dos genes codificantes das OXA-carbapenemases prevalentes em Acinetobacter baumannii: blaOXA-51, blaOXA-23, blaOXA-24, blaOXA-58 e blaOXA-143 através da técnica de PCR multiplex. A epidemiologia molecular dos isolados resistentes aos carbapenêmicos também foi estudada, através da tipagem molecular utilizando-se a técnica de pulsed-field gel electroforesis (PFGE). Alta taxa de resistência a todas as classes de antimicrobianos testados, em especial aos carbapenêmicos (67,4%) foi observada nos isolados. Todos os isolados resistentes aos carbapenêmicos foram positivos para o gene blaOXA-51, confirmando a identificação da espécie Acinetobacter baumannii (94%) e, a presença do gene blaOXA-23 foi observada em todos estes isolados. Nenhum isolado apresentou positividade para os genes blaOXA-24, blaOXA-58 e blaOXA-143, destes e dos isolados positivos para a carbapenemase OXA-51-like e negativos para OXA-23-like, todos foram sensíveis aos carbapenêmicos (32,6%). Em 8 (6%) isolados o mecanismo de resistência não pode ser inferido pois não houve amplificação com nenhum dos primers utilizados neste estudo. Apenas 4 (3%) isolados foram resistentes à polimixina B, e destes todos foram resistentes aos carbapenêmicos, sendo que 48/132 (36,4%) isolados de Acinetobacter foram resistentes a todos os antimicrobianos testados, exceto polimixina B. A maioria desses isolados multirresistentes (MRs) são A. baumannii e apresentaram CIMs 87%) de A. baumannii resistente aos carbapenêmicos (AbRC), com dois clones majoritários contendo isolados pertencentes a todos os hospitais, o que pode ser indicativo de disseminação inter-hospital destes isolados AbRC na cidade de Porto Alegre.Acinetobacter baumannii is a bacterium of great clinical importance, being the cause of many nosocomial infections, including bacteremia, pneumonia and meningitis. The treatment of these infections has become critical due to the emergence of multiresistant strains that are resistant to the most commomly used antimicrobial agents in clinical practice and also to carbapenems, polymyxin B is the best therapeutic alternative in such cases. The present study evaluated the susceptibility to different classes of antibiotics, especially carbapenems and polymyxin B, of 132 Acinetobacter spp. isolates, obtained from March to December 2011 at three hospitals in Porto Alegre. The susceptibility was evaluated by minimum inhibitory concentration (MIC) using broth microdilution protocol according to the Clinical and Laboratory Standards Institute (CLSI) criteria, for the following antimicrobial agents: ampicillin/sulbactam, imipenem, meropenem, cefepime, ceftazidime, ciprofloxacin, polymyxin B and tigecycline. Additionally we sought to evaluate the mechanisms of carbapenem resistance by investigating the genes encoding the prevalent OXAcarbapenemases in Acinetobacter baumannii: blaOXA-51, blaOXA-23, blaOXA-24, blaOXA-58 and blaOXA-143 by multiplex PCR. The molecular epidemiology of carbapenem resistant isolates was also studied by molecular typing using the pulsed-field gel electrophoresis (PFGE) technique. High rate of resistance to all classes of antimicrobials, especially to carbapenems (67.4%) was observed to almost all isolates. All carbapenem-resistant isolates were positive for the gene blaOXA-51, confirming the identification of Acinetobacter baumannii (94%) and the presence of blaOXA-23 gene was observed in all these isolates. No isolate was positive for the genes blaOXA-24, blaOXA-58 and blaOXA-143, and all positive isolates for OXA-51-like carbapenemase and negative for OXA-23-like, were sensitive to carbapenems (32.6 %). In 8 (6%) isolates the resistance mechanism could not be inferred since there was no amplification product with the primers used in this study. Only 4 (3%) isolates were resistant to polymyxin B, and all of these were also resistant to carbapenems, and 48/132 (36.4%) isolates of Acinetobacter were resistant to all antibiotics tested, except polymyxin B. The majority of these multiresistant (MR) isolates belong to A. baumannii species and have MICs 87%) of carbapenem resistant A. baumannii (CRAb), with two major clones containing isolates belonging to all hospitals, which may be indicative of inter-hospital spread of these CRAb isolates in Porto Alegre city

Characterization and molecular epidemiology of carbapenem resistant and sensitive Acinetobacter baumannii isolates from three hospitals in Porto Alegre

Acinetobacter baumannii é uma bactéria de grande importância clínica, sendo causa de diversas infecções nosocomiais, incluindo bacteremias, pneumonia e meningites. O tratamento dessas infecções tem se tornado crítico em função do surgimento de isolados resistentes aos antimicrobianos mais utilizados na prática clínica e também aos carbapenêmicos, tendo como melhor alternativa terapêutica, nestes casos, a polimixina B. O presente estudo avaliou o perfil de susceptibilidade a diferentes classes de antimicrobianos, em especial aos carbapenêmicos e polimixina B, em 132 isolados de Acinetobacter spp., isolados no período de março a dezembro de 2011 em três hospitais de Porto Alegre. A susceptibilidade foi avaliada pela determinação da Concentração Inibitória Mínima (CIM) através da técnica de microdiluição em caldo de acordo com os critérios do Clinical and Laboratory Standards Institute (CLSI), para os seguintes antimicrobianos: ampicilina/sulbactama, imipenem, meropenem, cefepima, ceftazidima, ciprofloxacina, polimixina B e tigeciclina. Adicionalmente buscou-se avaliar os mecanismos de resistência aos carbapenêmicos através da pesquisa dos genes codificantes das OXA-carbapenemases prevalentes em Acinetobacter baumannii: blaOXA-51, blaOXA-23, blaOXA-24, blaOXA-58 e blaOXA-143 através da técnica de PCR multiplex. A epidemiologia molecular dos isolados resistentes aos carbapenêmicos também foi estudada, através da tipagem molecular utilizando-se a técnica de pulsed-field gel electroforesis (PFGE). Alta taxa de resistência a todas as classes de antimicrobianos testados, em especial aos carbapenêmicos (67,4%) foi observada nos isolados. Todos os isolados resistentes aos carbapenêmicos foram positivos para o gene blaOXA-51, confirmando a identificação da espécie Acinetobacter baumannii (94%) e, a presença do gene blaOXA-23 foi observada em todos estes isolados. Nenhum isolado apresentou positividade para os genes blaOXA-24, blaOXA-58 e blaOXA-143, destes e dos isolados positivos para a carbapenemase OXA-51-like e negativos para OXA-23-like, todos foram sensíveis aos carbapenêmicos (32,6%). Em 8 (6%) isolados o mecanismo de resistência não pode ser inferido pois não houve amplificação com nenhum dos primers utilizados neste estudo. Apenas 4 (3%) isolados foram resistentes à polimixina B, e destes todos foram resistentes aos carbapenêmicos, sendo que 48/132 (36,4%) isolados de Acinetobacter foram resistentes a todos os antimicrobianos testados, exceto polimixina B. A maioria desses isolados multirresistentes (MRs) são A. baumannii e apresentaram CIMs 87%) de A. baumannii resistente aos carbapenêmicos (AbRC), com dois clones majoritários contendo isolados pertencentes a todos os hospitais, o que pode ser indicativo de disseminação inter-hospital destes isolados AbRC na cidade de Porto Alegre.Acinetobacter baumannii is a bacterium of great clinical importance, being the cause of many nosocomial infections, including bacteremia, pneumonia and meningitis. The treatment of these infections has become critical due to the emergence of multiresistant strains that are resistant to the most commomly used antimicrobial agents in clinical practice and also to carbapenems, polymyxin B is the best therapeutic alternative in such cases. The present study evaluated the susceptibility to different classes of antibiotics, especially carbapenems and polymyxin B, of 132 Acinetobacter spp. isolates, obtained from March to December 2011 at three hospitals in Porto Alegre. The susceptibility was evaluated by minimum inhibitory concentration (MIC) using broth microdilution protocol according to the Clinical and Laboratory Standards Institute (CLSI) criteria, for the following antimicrobial agents: ampicillin/sulbactam, imipenem, meropenem, cefepime, ceftazidime, ciprofloxacin, polymyxin B and tigecycline. Additionally we sought to evaluate the mechanisms of carbapenem resistance by investigating the genes encoding the prevalent OXAcarbapenemases in Acinetobacter baumannii: blaOXA-51, blaOXA-23, blaOXA-24, blaOXA-58 and blaOXA-143 by multiplex PCR. The molecular epidemiology of carbapenem resistant isolates was also studied by molecular typing using the pulsed-field gel electrophoresis (PFGE) technique. High rate of resistance to all classes of antimicrobials, especially to carbapenems (67.4%) was observed to almost all isolates. All carbapenem-resistant isolates were positive for the gene blaOXA-51, confirming the identification of Acinetobacter baumannii (94%) and the presence of blaOXA-23 gene was observed in all these isolates. No isolate was positive for the genes blaOXA-24, blaOXA-58 and blaOXA-143, and all positive isolates for OXA-51-like carbapenemase and negative for OXA-23-like, were sensitive to carbapenems (32.6 %). In 8 (6%) isolates the resistance mechanism could not be inferred since there was no amplification product with the primers used in this study. Only 4 (3%) isolates were resistant to polymyxin B, and all of these were also resistant to carbapenems, and 48/132 (36.4%) isolates of Acinetobacter were resistant to all antibiotics tested, except polymyxin B. The majority of these multiresistant (MR) isolates belong to A. baumannii species and have MICs 87%) of carbapenem resistant A. baumannii (CRAb), with two major clones containing isolates belonging to all hospitals, which may be indicative of inter-hospital spread of these CRAb isolates in Porto Alegre city

Chitotriosidase on treatment-naïve patients with Gaucher disease : A genotype vs phenotype study

Background Chitotriosidase (ChT) is used as a biomarker for the follow-up of patients with Gaucher disease (GD), once his activity is extremely elevated and declines during ERT. However, some variants in the CHIT1 gene affect ChT activity. Methods To assess association between ChT genotype, and clinical/biochemical features of GD were performed CHIT1 genotyping for: c.1049_1072dup24, p.Gly102Ser, p.Gly354Arg, c.1155_1156 + 2delGAGT, c.1156 + 5_1156 + 8delGTAA, p.Ala442Val/Gly and the rearrangement delE/I-10. Results Were evaluated 42 patients with GD from Southern Brazil. Pretreatment ChT activity was available for 32 patients. Allelic frequencies found for dup24, p.Gly102Ser and p.Ala442Gly were 0.14, 0.32 and 0.12, respectively. Only one patient presented reduced ChT activity (dup24 homozygous). Comparison between wild homozygous and heterozygous for dup24 showed that both differ in relation to the ChT activity before (15,230 vs 6936 nmol/h/mL, p < .001), but not after treatment (5212 vs 3045 nmol/h/mL, p = .227). Conclusions Pretreatment ChT activity was not correlated with clinical/biochemical features. There was a reduction of 63% in the ChT activity after 12 months on treatment (p < .001). There is no evidence that higher ChT levels are associated with a more severe symptomatology in untreated GD patients. The pretreatment ChT levels appear to be mainly dependent on the presence/absence of the dup24 allele