Molecular Characterization of Carbapenem-Resistant Acinetobacter baumannii in the Intensive Care Unit of Uruguay's University Hospital Identifies the First rmtC Gene in the Species.

Carbapenem-resistant Acinetobacter baumannii (CRAB) infections are an increasing concern in intensive care units (ICUs) worldwide. The combination of carbapenemases and 16S rRNA-methyltransferases (16S-RMTases) further reduces the therapeutic options. OXA-carbapenemase/A. baumannii clone tandems in Latin America have already been described; however, no information exists in this region regarding the occurrence of 16S-RMTases in this microorganism. In addition, the epidemiology of A. baumannii in ICUs and its associated resistance profiles are poorly understood. Our objectives were as follows: to study the clonal relationship and antibiotic resistance profiles of clinical and digestive colonizing A. baumannii isolates in an ICU, to characterize the circulating carbapenemases, and to detect 16S-RMTases. Patients admitted between August 2010 and July 2011 with a clinically predicted hospital stay > 48 hr were included. Pharyngeal and rectal swabs were obtained during the first fortnight after hospitalization. Resistance profiles were determined with MicroScan® and VITEK2 system. Carbapenemases and 16S-RMTases were identified by PCR and sequencing, and clonality was assessed by pulsed-field gel electrophoresis and multilocus sequence typing. Sixty-nine patients were studied and 63 were diagnosed with bacterial infections. Among these, 29 were CRAB isolates; 49 A. baumannii were isolated as digestive colonizers. These 78 isolates were clustered in 7 pulsetypes, mostly belonging to ST79. The only carbapenemase genes detected were blaOXA-51 (n = 78), blaOXA-23 (n = 62), and blaOXA-58 (n = 3). Interestingly, two clinical isolates harbored the rmtC 16S-RMTase gene. To the best of our knowledge, this is the first description of the presence of rmtC in A. baumannii.

Actualización acerca de colistina (polimixina E): aspectos clínicos, PK/PD y equivalencias / Colistin: an update on the antibiotic: clinical aspects PK/PD indices and equivalences

En los últimos diez años, en esta era posantibiótica, la colistina ha resurgido como un último recurso frente a infecciones por patógenos como Pseudomonas aeruginosa, Acinetobacter baumannii complex y enterobacterias productoras de carbapenemasas. Cayó en desuso previamente dados sus efectos adversos potencialmente graves, como la nefro y neurotoxicidad, pero hoy revive como parte fundamental de los planes antibióticos frente a patógenos extremadamente resistentes. El aumento de su uso conlleva a la emergencia de resistencia, encontrándonos frente a una situación potencialmente catastrófica, en particular dada la recientemente descrita presencia de plásmidos transferibles entre especies conteniendo genes que confieren resistencia a colistina (gen mcr-1), mecanismo detectado también en nuestro país. En la presente revisión, basados en los conocimientos actuales sobre la farmacocinética y la farmacodinamia, se describe en detalle la dosificación apropiada con necesidad de realizar dosis carga para alcanzar los niveles terapéuticos adecuados, así como aspectos prácticos de la administración en casos de meningitis/ventriculitis posquirúrgica y del empleo por vía nebulizada para el tratamiento de la neumonía asociada a la ventilación. Se destaca la necesidad de su uso combinado con otro antibiótico activo in vitro, en particular en pacientes críticos y en aquellos con un clearance de creatininemia mayor a 80 ml/min. La biterapia es necesaria en particular si la concentración inhibitoria mínima (CIM) del patógeno es mayor a 1 mg/l, debido al riesgo de subdosificación y emergencia de resistencia intratratamiento. En una segunda sección se aborda la complejidad de la dosificación en función de las distintas presentaciones comercializadas a nivel nacional que han conducido a errores en la posología, con un riesgo mayor de eventual toxicidad. Con el objetivo de mejorar la comprensión referente a la rotulación de la dosis a administrar de colistina se revisaron los insertos y envases primarios de las presentaciones de colistina comercialmente disponibles en Uruguay, a efectos de solicitar formal y documentalmente a las empresas farmacéuticas representantes, se expidan en cuanto a los contenidos de colistina (droga activa) y de su profármaco, el colistimetato sódico (CMS). Finalmente se elaboraron una serie de recomendaciones en cuanto a la información que a entender de los autores debieran exhibir las distintas presentaciones de colistina comercialmente disponibles para no inducir a errores en la prescripción.

In the recent 10 years, in this post-antibiotic era, colisitin has reappeared as the last resource to face infections caused by Pseudomonas aeruginosa, Acinetobacter baumannii complex and carbapenemase-producing enterobacteriaceae. At some point the use of colistin was discontinued given its potentially severe side effects, such as nephro and neurotoxicity , although it reemerges today as an essential part of antibiotic plans when facing extremely resistant pathogens. This increase in the use of colistin has led to an antibiotic resistance emergency and thus today we face a potentially catastrophic situation. This happens in particular in connection with the recently described presence of transferable plasmids among species containing genes that confer resistance to colistin (gen mcr-1), a mechanism also identified in our country. This review describes in detail the right dosing with the need to make load doses to achieve the appropriate therapeutic levels, based on current knowledge on pharmacokinetics and pharmacodynamics, as well as practical aspects in the administration of the drug in cases of postsurgical meningitis/ventriculitis and the use by nebulization for the treatment of ventilation associated pneumonia. The study points out the need to use colistin along with another in-vitro active antibiotic, especially in critical patients and those with a creatinine clearance over 80 ml/min. Dual pharmacotherapy is necessary in particular if the pathogen´s minimuminhibitory concentration (MIC) is higher than 1 mg/min, due to intra-treatment risk of sub-dosing and resistance emergency. Likewise, in second section, the study addresses the complex nature of dosing given by the different presentations available in the market at the national level, what has resulted in dosage errors, and thus a higher risk of toxicity. The insets and primary packaging of colistin presentation available in the Uruguayan marketing were reviewed with the purpose of improving understanding in connection with the labeling of the doses to be administered. With that information, the pharmaceutical industries agents will be formally asked in writing to inform the colistin content (active drug) and its prodrug colistimethate sodium. Last, a number of recommendations were prepared as to the Information the authors understand should appear in the different presentations of colistin that is available in the market, to avoid prescription errors.

Nos últimos 10 anos, nesta era pós-antibiótica, a colistina reapareceu como um último recurso para enfrentar infecções por patógenos como Pseudomonas aeruginosa, Acinetobacter baumannii complexo e enterobactérias produtoras de carbapenemases. Durante um período não foi utilizada devido a seus efeitos adversos potencialmente graves como a nefro e a neurotoxicidade, porém atualmente é parte fundamental da antibioticoterapia nos casos de patógenos extremadamente resistentes. O aumento de seu uso levou ao aparecimento de resistência e como consequência, de uma situação potencialmente catastrófica, especialmente a recentemente descrita presença de plasmídeos transferíveis entre espécies que contém genes que conferem resistência a colistina (gen mcr-1), mecanismo detectado também no Uruguai. Nesta revisão, baseados nos conhecimentos atuais sobre a farmacocinética e farmacodinâmica, descreve-se detalhadamente a dosagem apropriada com necessidade de realizar doses carga para alcançar os niveles terapêuticos adequados, e os aspectos práticos da administração nos casos de meningite/ventriculite pós-operatória e de seu emprego na nebulização para o tratamento da pneumonia associada à ventilação. Destaca-se a necessidade de seu uso combinado com outro antibiótico ativo in vitro, especialmente em pacientes críticos e naqueles com clearance de creatininemia maior a 80 ml/min. A bi terapia é necessária principalmente se a concentração inibitória mínima do patógeno é maior a 1 mg/l, devido ao risco de subnotificação e o aparecimento de resistência intratratamiento. Na segunda parte, discute-se a complexidade da dosagem em função das diferentes apresentações comercializadas no país que levaram a erros na posologia, com um maior risco de toxicidade. Buscando melhorar a compreensão dos aspectos relacionados a rotulação da dose de colistina revisaram-se as bulas e as embalagens primárias das apresentações de colistina comercialmente disponíveis no Uruguai, para solicitar formal e documentalmente às empresas farmacêuticas representantes, informação sobre a dosagem de colistina (droga ativa) e de seu precursor o colistimetato de sódio (CMS). Finalmente elabora-se uma série de recomendações com relação à informação que os autores consideram que deveria ser oferecida nas diferentes apresentações de colistina comercialmente disponíveis para não induzir a erros na prescrição.

CTX-M-15 in combination with aac(6')-Ib-cr is the most prevalent mechanism of resistance both in Escherichia coli and Klebsiella pneumoniae, including K. pneumoniae ST258, in an ICU in Uruguay.

The objectives of this study were (i) to determine the extended-spectrum ß-lactamase-producing Escherichia coli and Klebsiella pneumoniae (ESBL-EcKp) clones circulating in an intensive care unit (ICU) in Uruguay between August 2010 and July 2011, (ii) to characterise the ESBL and plasmid-mediated quinolone resistance (PMQR) genes of the studied isolates and (iii) to determine the virulotype of the clinical isolates. Clinical and gut-colonising ESBL-EcKp from ICU patients were studied. Bacterial identification and antibiotic susceptibility determination were performed using a VITEK(®)2 system. Detection of ESBL, KPC and PMQR genes was performed by PCR and sequencing. Clonality was assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). In total, 54 ESBL-EcKp isolates (40 K. pneumoniae and 14 E. coli), with or without PMQR genes, were recovered from 30 of 68 inpatients. Forty-seven isolates were CTX-M-15-producers (36 as a single ESBL and 11 together with CTX-M-14). In addition, four isolates produced CTX-M-14, two produced CTX-M-2 and one produced SHV-5. No carbapenemases were detected either in E. coli or K. pneumoniae isolates. Among the ESBL-producing isolates, 42 also harboured PMQR genes: 27 aac(6')-Ib-cr; 14 aac(6')-Ib-cr and qnrB; and a single isolate carrying only qnrB. K. pneumoniae ST258, ST48 and ST16 and E. coli ST10 and ST405 were detected in 46/54 isolates, including 9 clinical isolates. In conclusion, non-KPC-producing K. pneumoniae ST258 harbouring different ESBL and PMQR genes was the main clone disseminated in the ICU. Extensive surveillance measures must be implemented to prevent the emergence of acquired plasmid-encoded blaKPC by ST258 K. pneumoniae.

Polyclonal endemicity of Acinetobacter baumannii in ventilated patients in an intensive care unit in Uruguay.

OBJECTIVES: To identify the mechanisms responsible for respiratory infections by Acinetobacter baumannii in intubated patients and risk factors for digestive colonization and infection by A. baumannii. METHODS: We conducted a prospective study in an intensive care unit (ICU) between May 2005 and November 2006, including 175 consecutive patients at the beginning of invasive ventilation (day 1). We performed pharyngeal and rectal swabs on days 1, 4, 7, 10, 13, and 16. Respiratory samples were taken on days 1 and 7, or on suspicion of ventilator-associated pneumonia (VAP). RESULTS: We detected 62 patients with A. baumannii digestive colonization and 20 cases of A. baumannii lower respiratory infection (14 VAP and six purulent tracheobronchitis (PTB)). Digestive colonization by A. baumannii was an independent risk factor for lower respiratory tract infections with that microorganism (p<0.0001; relative risk 8.71, 95% confidence interval 2.73-27.77). Respiratory and rectal A. baumannii isolates from the same patients were compared by enterobacterial repetitive intergenic consensus (ERIC)-PCR; in 9/11 cases (eight VAP and one PTB) results suggested events of exogenous pneumonia with previous colonization, whereas the remaining two cases (two PTB) were suggestive of exogenous infection without previous colonization. CONCLUSIONS: In our unit the pathogenesis of VAP by A. baumannii is mixed, most cases corresponding to exogenous pneumonia with previous colonization.

Medicina genómica aplicada a la neumonía aguda comunitaria: [revisión] / Genomic medicine applied to acute community acquired pneumonia: [review]

Las infecciones del tracto respiratorio inferior constituyen un enorme flagelo para la humanidad. La neumonía aguda comunitaria es la principal enfermedad respiratoria por frecuencia y severidad. A pesar de los avances de la medicina moderna, su morbilidad y mortalidad permanecen prácticamente incambiadas.La respuesta ante un agravio infeccioso es estrictamente individual al estar influida por la estructura genética del huésped. La medicina genómica procura personalizar y optimizar el diagnóstico, pronóstico y tratamiento mediante el reconocimiento de la influencia que ejercen determinadas variantesgenéticas, denominadas polimorfismos, en la susceptibilidad y evolución de las diversas patologías. Los polimorfismos genéticos son capaces de modificar el riesgo de padecer determinadoevento o suceso en una enfermedad específica por lo cual su reconocimiento permite personalizar la interacción entre ambiente y huésped. En el presente artículo se describen los polimorfismos que están asociados positivamente conla evolución de la neumonía aguda comunitaria y qué aplicaciones clínicas podría tener la medicina genómica.

As infecções do trato respiratório inferior são um importante problema para a humanidade sendo a pneumonia aguda comunitária a principal doença respiratória por sua frequência e gravidade. Apesar dos avanços da medicina moderna sua morbidade e mortalidade permanecem praticamente inalteradas. A resposta ante um ataque infeccioso é estritamente individual por estar sujeita à estrutura genética do hóspede. A medicina genômica busca personalizar e otimizar o diagnóstico,prognóstico e tratamento reconhecendo a influencia que exercem determinadas variantes genéticas, denominadas polimorfismos, sobre a suscetibilidade e a evolução das diferentes patologias.Os polimorfismos genéticos são capazes de modificar o risco de sofrer determinado evento em uma doença específica pelo qual seu reconhecimento permite personalizar a interação entre ambiente e hóspede. Neste artigo os polimorfismos que estão associados positivamente com a evolução da pneumonia aguda comunitária e as possíveis aplicações clínicas da medicina genômica são descritos.

Lower respiratory tract infections constitute a serious problem for humanity. Community-acquired pneumonia is the main respiratory disease due to frequency and severity. Inspite of progress made by modern medicine, mortality and morbility rates remain unchanged. Response to an infectious attack is strictly personal as it is influenced by the hostÆs genetic structure. Genomic medicine aims to personalize and optimize diagnosis, prognosis and treatment by acknowledging the influence of certain genetic variations, called polymorphisms,on susceptibility and the evolution of several pathologies. Genetic polymorphisms are able to modify the risk of suffering a certain event or episode in a specific disease and being aware of this enables personalizing the interaction between the environment and the host. The present study describes polymorphisms that are positively associated to the evolution of acute-community acquired pneumoniaand the possible clinical applications by genomic medicine.