Acinetobacter baumannii, microorganisme responsable d’infections nosocomiales survenant le plus souvent par épidémies, pose un problème émergent de multi-résistance aux antibiotiques, notamment aux carbapénèmes. Cette résistance aux carbapénèmes est le plus souvent liée à l’acquisition et à l’expression de gènes codant pour des b-lactamases de classe D à activité de carbapénèmase (CHDLs). Le réservoir de ces gènes de résistance est inconnu.Nous avons montré que l’espèce bactérienne Acinetobacter radioresistens, espèce proche de A. baumannii, est le progéniteur du déterminant de résistance aux carbapénèmes le plus prévalent dans le monde chez A. baumannii : le gène blaOXA-23. Nous avons identifié l’espèce Acinetobacter lwoffii comme progéniteur d’un gène codant pour une nouvelle CHDL : OXA-134. Nous avons identifié les CHDLs naturelles des espèces Acinetobacter johnsonii, Acinetobacter calcoaceticus et Acinetobacter haemolyticus, dénommées respectivement OXA-211, OXA-213 et OXA-214. Nous avons ensuite étudié l’expression des gènes codant pour ces CHDLs naturelles en prenant l’exemple du gène naturel blaOXA-51/-66 de A. baumannii et nous avons démontré que ce gène était impliqué dans la réduction de sensibilité aux carbapénèmes chez A. baumannii, notamment lorsque la séquence d’insertion (IS) ISAba1 était présente en amont de ce gène. Nous avons ensuite identifié une nouvelle IS, ISAba9, à l’origine de la surexpression du gène blaOXA-51 naturel de A. baumannii. Enfin, nous avons identifié VIM-4, b-lactamase de classe B capable d’hydrolyser les carbapénèmes, dans une souche de Acinetobacter non-baumannii, Acinetobacter genomic species 16. / Carbapenem resistance in Acinetobacter baumannii is increasingly reported and leads to difficult-to-treat nosocomial infections. Carbapenem-hydrolyzing class D b-lactamases (CHDLs) represent the main mechanism of resistance to carbapenems in Acinetobacter spp. The origin (reservoir) of those CHDL genes remains unknown. We identified Acinetobacter radioresistens as the reservoir of the blaOXA-23-like genes currently emerging as the sources of carbapenem resistance in A. baumannii worldwide. Acinetobacter lwoffii was found to be a reservoir of a novel type of CHDL-encoding gene: blaOXA-134. We described the naturally-occurring CHDLs from Acinetobacter johnsonii, Acinetobacter calcoaceticus and Acinetobacter haemolyticus, respectively named OXA-211, OXA-213 et OXA-214. We reported an in vivo selection of reduced susceptibility to carbapenems in A. baumannii. This reduced susceptibility to carbapenems was related to selection of the ISAba1-related overexpression of the naturrally-occurring blaOXA-51/-69 gene from A. baumannii. We identified the novel insertion sequence ISAba9 as being involved in blaOXA-51/-69 gene overexpression, thus contributing to carbapenem resistance in A. baumannii.We reported the first identification of the metallo-b-lactamase VIM-4 determinant in Acinetobacter spp.

Carbapenem resistance in Acinetobacter baumannii is a growing public health concern and represents a serious problem for treatment of the infection. Several carbapenem-hydrolysing &beta / -lactamases have been identified from A. baumannii so far. In this study carbapenem resistance in A.baumannii strains recovered from intensive care units of Gulhane Military Medical Academy, Turkey, were investigated via multiplex PCR and with parallel phenotypic tests. From June 2006 to January 2010, 138 clinical A. baumannii isolates were collected. Identification and antimicrobial susceptibility tests of the isolates were performed. The MICs of imipenem and meropenem were determined by using E-test method. Carbapenem resistant A. baumannii strains were included for further study. Firstly, the presence of carbapenemases were determined. The presence of Metallo-beta-lactamase (MBL) were also investigated. Detection of the four groups of OXA carbapenemases (OXA- 23, OXA-24, OXA-51 and OXA-58) was carried out using a multiplex PCR assay. Sequence analyses were performed. Non-duplicate, multidrug resistant 61 clinical A. baumannii isolates were found to be resistant to imipenem and meropenem. In the 61 isolates, the MIC50 of imipenem and meropenem were 16 and &gt / 32 / MIC90 were 192 and &gt / 32 respectively. Modified Hodge Tests (MHT) were positive for all 61 A. baumannii strains. None of these isolates showed MBL activity. As determined through multiplex PCR, all of the 61 isolates had blaOXA-51 genes, 50 isolates had blaOXA-23, and 11 isolated had blaOXA-58 genes. Alleles encoding OXA-24-like enzymes were not detected in any isolates. This study indicated that the clinical isolates in our region contained blaOXA-51, blaOXA-23, and blaOXA-58 resistance genes. However, blaOXA-24 gene was either absent or occur in very low frequency.

Acinetobacter baumannii, microorganisme responsable d'infections nosocomiales survenant le plus souvent par épidémies, pose un problème émergent de multi-résistance aux antibiotiques, notamment aux carbapénèmes. Cette résistance aux carbapénèmes est le plus souvent liée à l'acquisition et à l'expression de gènes codant pour des b-lactamases de classe D à activité de carbapénèmase (CHDLs). Le réservoir de ces gènes de résistance est inconnu.Nous avons montré que l'espèce bactérienne Acinetobacter radioresistens, espèce proche de A. baumannii, est le progéniteur du déterminant de résistance aux carbapénèmes le plus prévalent dans le monde chez A. baumannii : le gène blaOXA-23. Nous avons identifié l'espèce Acinetobacter lwoffii comme progéniteur d'un gène codant pour une nouvelle CHDL : OXA-134. Nous avons identifié les CHDLs naturelles des espèces Acinetobacter johnsonii, Acinetobacter calcoaceticus et Acinetobacter haemolyticus, dénommées respectivement OXA-211, OXA-213 et OXA-214. Nous avons ensuite étudié l'expression des gènes codant pour ces CHDLs naturelles en prenant l'exemple du gène naturel blaOXA-51/-66 de A. baumannii et nous avons démontré que ce gène était impliqué dans la réduction de sensibilité aux carbapénèmes chez A. baumannii, notamment lorsque la séquence d'insertion (IS) ISAba1 était présente en amont de ce gène. Nous avons ensuite identifié une nouvelle IS, ISAba9, à l'origine de la surexpression du gène blaOXA-51 naturel de A. baumannii. Enfin, nous avons identifié VIM-4, b-lactamase de classe B capable d'hydrolyser les carbapénèmes, dans une souche de Acinetobacter non-baumannii, Acinetobacter genomic species 16.

As espécies do Complexo Acinetobacter calcoaceticus-A. baumannii (ACB) são importantes causadoras de Infecções Relacionadas à Assistência à Saúde em todo o mundo. Detêm maior relevância os isolados com resistência aos antimicrobianos, os quais impactam negativamente no prognóstico, na mortalidade e custos associados ao cuidado com o paciente. O objetivo deste estudo foi avaliar a diversidade genética e o perfil de susceptibilidade antimicrobiana de 134 isolados multirresistentes de A. baumannii presentes no Hospital das Clínicas da Faculdade de Medicina de Botucatu, entre 2007 e 2014. A identificação de A. baumannii deu-se pela pesquisa dos genes blaOXA-51-like e gltA, detectados em 85% (n=114) dos isolados Os isolados de Acinetobacter não-baumannii foram identificados por sequenciamento gênico como A. nosocomialis (n=4; 3,1%), A. pittii, A. bereziniae (n=2; 1,7%, cada), A. ursingii, A. variabilis, A. gyllenbergii (n=1; 0,9% cada) e Acinetobacter spp (n=2; 1,7%). Os isolados de A. baumannii foram submetidos às técnicas de PCR multiplex para detecção de outras oxacilinases, pesquisa de ISAba1, teste de susceptibilidade antimicrobiana, tipagem molecular por eletroforese em campo pulsado (PFGE), por sequência trilocus (3LST) e por sequência multilocus (MLST). Detectou-se o gene blaOXA-23-like em 105 isolados (92,1%), estando 100% associados a ISAba1; blaOXA-72 em um isolado (0,9%) e blaOXA-231 em dois isolados (1,7%). A maior parte (n=66; 57,9%) dos isolados foi classificada como extensivamente resistentes (XDR). O PFGE agrupou os isolados em 11 clusters (A-K) e o MLST identificou os isolados pertencentes majoritariamente aos clones CC79 (42,4%), CC1 (16,6%), CC15 (12,1%) e ao ST317 (18,2%). Os resultados do MLST e 3LST concordaram em 95,6%. Foi verificada a ocorrência de diferentes perfis de PFGE em A. baumannii MDR e XDR, predominando cepas carreadoras de ISAba1/OXA-23-like e pertencentes aos CC1, CC15, CC79, ST317. Predominaram o ST317 nos anos iniciais e o CC79 (ST730) de 2011 a 2014. Estes resultados fornecem subsídios que ressaltam a necessidade de monitoramento e controle de patógenos multirresistentes / Species of Acinetobacter calcoaceticus-A. baumannii Complex (ACB) are important causes of Healthcare Associated Infections worldwide. More relevant are isolates with antimicrobial resistance, which have a negative impact on the outcome, mortality and costs associated with patient care. The aim of this study was to evaluate the genetic diversity and the antimicrobial susceptibility profile of 134 multiresistant ACB spcies strains present at Botucatu Medical School Teaching Hospital between 2007 and 2014. Identification of A. baumannii species was by detection of blaOXA-51-like and gltA genes, detected in 85% (n=114) of the isolates. Non-baumannii Acinetobacter species were identified by gene sequencing as A. nosocomialis (n=4, 3.1%), A. ursingii, A. variabilis, A. gyllenbergii (n=1, 0.9% each) and Acinetobacter spp (n=2; 1.7%). A. baumannii isolates were submitted to multiplex PCR for other oxacillinases and ISAba1 detection, antimicrobial susceptibility testing, molecular typing by pulsed field gel electrophoresis (PFGE), trilocus sequence typing (3LST) and multilocus sequence typing (MLST). blaOXA-23-like gene was detected in 105 isolates (92.1%), of which 100% were associated with ISAba1; blaOXA-72 was present in one isolate (0.9%) and blaOXA-231, in two isolates (1.7%). The majority (n=66; 57.9%) of isolates were classified as extensively resistant (XDR). The PFGE grouped the isolates into 11 clusters (A-K) and MLST identified the isolates belonging mainly to CC79 (42.4%), CC1 (16.6%), CC15 (12.1%) and ST317 (18.2%). MLST and 3LST results were 95.6% concordant. We verified the occurrence of different PFGE profiles in multidrug-resistant (MDR) and extensively drug-resistant (XDR) A. baumannii, predominantly presenting ISAba1/OXA-23-like genes and belonging to CC1, CC15, CC79 and ST317. There was a prevalence of ST317 in the early years and CC79 (ST730) from 2011 to 2014. Our results highlight the importance of surveillance and control of multiresistant pathogens

As espécies do Complexo Acinetobacter calcoaceticus-A. baumannii (ACB) são importantes causadoras de Infecções Relacionadas à Assistência à Saúde em todo o mundo. Detêm maior relevância os isolados com resistência aos antimicrobianos, os quais impactam negativamente no prognóstico, na mortalidade e custos associados ao cuidado com o paciente. O objetivo deste estudo foi avaliar a diversidade genética e o perfil de susceptibilidade antimicrobiana de 134 isolados multirresistentes de A. baumannii presentes no Hospital das Clínicas da Faculdade de Medicina de Botucatu, entre 2007 e 2014. A identificação de A. baumannii deu-se pela pesquisa dos genes blaOXA-51-like e gltA, detectados em 85% (n=114) dos isolados Os isolados de Acinetobacter não-baumannii foram identificados por sequenciamento gênico como A. nosocomialis (n=4; 3,1%), A. pittii, A. bereziniae (n=2; 1,7%, cada), A. ursingii, A. variabilis, A. gyllenbergii (n=1; 0,9% cada) e Acinetobacter spp (n=2; 1,7%). Os isolados de A. baumannii foram submetidos às técnicas de PCR multiplex para detecção de outras oxacilinases, pesquisa de ISAba1, teste de susceptibilidade antimicrobiana, tipagem molecular por eletroforese em campo pulsado (PFGE), por sequência trilocus (3LST) e por sequência multilocus (MLST). Detectou-se o gene blaOXA-23-like em 105 isolados (92,1%), estando 100% associados a ISAba1; blaOXA-72 em um isolado (0,9%) e blaOXA-231 em dois isolados (1,7%). A maior parte (n=66; 57,9%) dos isolados foi classificada como extensivamente resistentes (XDR). O PFGE agrupou os isolados em 11 clusters (A-K) e o MLST identificou os isolados pertencentes majoritariamente aos clones CC79 (42,4%), CC1 (16,6%), CC15 (12,1%) e ao ST317 (18,2%). Os resultados do MLST e 3LST concordaram em 95,6%. Foi verificada a ocorrência de diferentes perfis de PFGE em A. baumannii MDR e XDR, predominando cepas carreadoras de ISAba1/OXA-23-like e pertencentes aos CC1, CC15, CC79, ST317. Predominaram o ST317 nos anos iniciais e o CC79 (ST730) de 2011 a 2014. Estes resultados fornecem subsídios que ressaltam a necessidade de monitoramento e controle de patógenos multirresistentes / Species of Acinetobacter calcoaceticus-A. baumannii Complex (ACB) are important causes of Healthcare Associated Infections worldwide. More relevant are isolates with antimicrobial resistance, which have a negative impact on the outcome, mortality and costs associated with patient care. The aim of this study was to evaluate the genetic diversity and the antimicrobial susceptibility profile of 134 multiresistant ACB spcies strains present at Botucatu Medical School Teaching Hospital between 2007 and 2014. Identification of A. baumannii species was by detection of blaOXA-51-like and gltA genes, detected in 85% (n=114) of the isolates. Non-baumannii Acinetobacter species were identified by gene sequencing as A. nosocomialis (n=4, 3.1%), A. ursingii, A. variabilis, A. gyllenbergii (n=1, 0.9% each) and Acinetobacter spp (n=2; 1.7%). A. baumannii isolates were submitted to multiplex PCR for other oxacillinases and ISAba1 detection, antimicrobial susceptibility testing, molecular typing by pulsed field gel electrophoresis (PFGE), trilocus sequence typing (3LST) and multilocus sequence typing (MLST). blaOXA-23-like gene was detected in 105 isolates (92.1%), of which 100% were associated with ISAba1; blaOXA-72 was present in one isolate (0.9%) and blaOXA-231, in two isolates (1.7%). The majority (n=66; 57.9%) of isolates were classified as extensively resistant (XDR). The PFGE grouped the isolates into 11 clusters (A-K) and MLST identified the isolates belonging mainly to CC79 (42.4%), CC1 (16.6%), CC15 (12.1%) and ST317 (18.2%). MLST and 3LST results were 95.6% concordant. We verified the occurrence of different PFGE profiles in multidrug-resistant (MDR) and extensively drug-resistant (XDR) A. baumannii, predominantly presenting ISAba1/OXA-23-like genes and belonging to CC1, CC15, CC79 and ST317. There was a prevalence of ST317 in the early years and CC79 (ST730) from 2011 to 2014. Our results highlight the importance of surveillance and control of multiresistant pathogens