Caracterização fenotípica e molecular de isolados de Salmonella spp. e Escherichia coli Patogênica Extraintestinal resistentes às polimixinas / Phenotypic and molecular characterization of Salmonella spp. and extraintestinal pathogenic Escherichia coli resistant to polymyxins

A resistência antimicrobiana está se tornando um grande desafio para saúde pública devido ao aumento da resistência aos beta-lactâmicos em geral. Os isolados de Salmonella spp. e Escherichia coli são os mais frequentes agentes causadores de doenças de transmissão hídrica e alimentar, mas também podem causar doenças invasivas graves, principalmente em imunodeprimidos, idosos e crianças. Ambos os patógenos vêm apresentando perfis de resistência as principais classes de antibióticos, nestes casos é necessária a busca de uma nova opção terapêutica, como por exemplo, as polimixinas. Em 2015, surgiu o primeiro relato da resistência às polimixinas mediado pelo gene mcr (mobile colistin resistance), que se disseminou por diversos continentes e ocasionou uma grande preocupação global em saúde pública. O objetivo deste trabalho foi identificar e caracterizar os mecanismos que medeiam à resistência à polimixinas em cepas de Salmonella spp. e E. coli Patogênica extraintestinal (ExPEC). Foi realizado a triagem pelo teste da gota e teste da CIM frente a colistina e polimixina B no total de 1026 isolados de Salmonella enterica e 159 isolados de ExPEC. Nos isolados resistentes foi verificado a presença de mutações nos genes (pmrA/B, phoP/Q) associados à resistência às polimixinas, e através da PCR foi feita a identificação dos genes de resistência plasmidial (mcr). Das 124 cepas de Salmonella resistentes a colistina e polimixina B, apenas um isolado foi positivo para o gene mcr-1, e este gene foi detectado em um plasmídeo do grupo IncX4. A cepa 2018.466 foi caracterizada como S. Choleraesuis proveniente de sangue de origem humana. Foram identificados 44 isolados de Salmonella spp. apresentando mutações em pmrA e pmrB. Dos 56 isolados de ExPEC resistentes a colistina, 21 isolados apresentaram o gene mcr-1. Este gene foi detectado em plasmídeos do grupo IncX4 (n=17) e em plasmídeos do grupo IncF (n=4). Cinco isolados de E.coli não apresentaram mutações nos genes estudados,sendo que três eram positivos para o gene mcr-1, enquanto as demais cepas apresentaram mutações em pmrA/B e phoP/Q. A tipagem pela PFGE foi realizada nos isolados de E.coli positivos para o gene mcr-1, com o objetivo de verificar a diversidade genética encontrada entre elas. Foram identificados 18 perfis genéticos, sem um clone principal...(AU)

Antimicrobial resistance is becoming a major public health challenge due to increasing resistance to beta-lactams in general. Salmonella spp. and Escherichia coli are the most frequent causative agents of diseases transmitted by water and food, but they can also cause serious invasive diseases, especially in immunosuppressed individuals, the elderly and children. Both pathogens have shown resistance profiles to the main classes of antibiotics, in these cases it is necessary to search for a new therapeutic option, such as polymyxins. In 2015, the first report of resistance to polymyxins mediated by the mcr gene (mobile colistin resistance) appeared, which spread across several continents and caused a major global concern in public health. The objective of this work was to identify and characterize the mechanisms that mediate resistance to polymyxins in strains of Salmonella spp. and extraintestinal pathogenic E. coli (ExPEC). Screening by drop test and MIC test against colistin and polymyxin B was performed on a total of 1026 Salmonella enterica isolates and 159 ExPEC isolates. In the resistant isolates, the presence of mutations in the genes (pmrA/B, phoP/Q) associated with resistance to polymyxins was verified, and through PCR the plasmid resistance genes (mcr) were identified. Of the 124 Salmonella strains resistant to colistin and polymyxin B, only one isolate was positive for the mcr-1 gene, and this gene was detected in a plasmid from the IncX4 group. Strain 2018.466 was characterized as S. Choleraesuis from blood of human origin. Forty-four Salmonella spp. showing mutations in pmrA and pmrB. Of the 56 colistin-resistant ExPEC isolates, 21 isolates harbored the mcr-1 gene. This gene was detected in plasmids from the IncX4 group (n=17) and in plasmids from the IncF group (n=4). Five E.coli isolates did not show mutations in the genes studied, three of which were positive for the mcr-1 gene, while the other strains showed mutations in pmrA/B and phoP/Q. Typing by PFGE was performed on E.coli isolates positive for the mcr-1 gene, with the objective of verifying the genetic diversity found among them. Eighteen genetic profiles were identified, without a main clone...(AU)

Infección de piel y tejidos blandos por Burkholderia stabilis en un niño con quemaduras graves / Skin and soft tissue infection due to Burkholderia stabilis in a severely burned child

Resumen Las heridas por quemadura representan un grave problema, sobre todo en la población pediátrica, dada la severidad de su presentación y la morbimortalidad asociada. La infección es la complicación más frecuente y grave en el paciente quemado. Las bacterias que conforman el complejo Burkholderia cepacia (CBc) son capaces de causar enfermedades en plantas, humanos y animales. En el hombre pueden establecer infecciones crónicas y frecuentemente graves, por lo general en pacientes con fibrosis quística y en inmunocomprometidos. El CBc está compuesto por al menos 22 especies filogenéticamente muy relacionadas. El objetivo de esta publicación fue describir el primer caso de una infección de piel y partes blandas por Burkholderia stabilis, una especie poco frecuente, en un niño con grandes quemaduras en la Argentina. Las especies del CBc son intrínsecamente resistentes a la mayoría de los antimicrobianos disponibles clínicamente, como aminoglucósidos, quinolonas, polimixinas y β-lactámicos. Esto representa un serio problema en el momento de tratar las infecciones por las escasas opciones terapéuticas.

Abstract Burn wounds represent a serious problem, especially in the pediatric population, given the severity of their presentation and the associated morbidity and mortality. Infection is the most frequent and serious complication in the burned patient. Burkholderia cepacia (CBc) complex bacteria are capable of causing disease in plants, humans, and animals. In human beings they can establish chronic and frequently serious infections, generally in patients with cystic fibrosis and in immunocompromised patients. The CBc is composed of 22 phylogenetically closely related species. The objective of this publication was to describe the first report of a skin and soft tissue infection by Burkholderia stabilis, a rare species, in a child with extensive burns in Argentina. CBc species are inherently resistant to most clinically available antimicrobials, such as aminoglycosides, quinolones, polymyxins, and β-lactams. This represents a serious problem when treating infections, due to the limited therapeutic options.

Resumo As feridas por queimadura representam um grave problema, principalmente na população pediátrica, devido à gravidade de sua apresentação e morbimortalidade associada. A infecção é a complicação mais frequente e grave do paciente queimado. As bactérias que compõem o complexo Burkholderia cepacia (CBc) são capazes de causar doenças em plantas, humanos e animais. No homem, podem estabelecer infecções crônicas e freqüentemente graves, geralmente em pacientes com fibrose cística e imunocomprometidos. O CBc é composto, no mínimo, por 22 espécies filogeneticamente muito relacionadas. O objetivo desta publicação é descrever o primeiro caso de uma infecção de pele e tecidos moles por Burkholderia stabilis, uma espécie rara, em uma criança com queimaduras extensas na Argentina. As espécies do CBc são inerentemente resistentes à maioria dos antimicrobianos disponíveis clinicamente, como aminoglicosídeos, quinolonas, polimixinas e β-lactâmicos. Isso representa um problema sério na hora de tratar as infecções devido às opções terapêuticas limitadas.

Resistência aos antimicrobianos e diversidade genética de variantes fenotípicas de Pseudomonas aeruginosa não sensíveis aos carbapenêmicos recuperadas de pacientes com fibrose cística com infecção pulmonar crônica: uma análise temporal / Antimicrobial resistance and genetic diversity of phenotypic variants of carbapenem non susceptible Pseudomonas aeruginosa recovered from patients with cystic fibrosis with chronic lung infection: a temporal analysis

Pseudomonas aeruginosa, bactéria ubíqua e versátil, pode se comportar como um patógeno oportunista, com ampla capacidade adaptativa, por múltiplos fatores de virulência e resistência. Como agente patogênico nas infecções pulmonares em pacientes com fibrose cística (FC), é motivo de prognóstico ruim, aumento de hospitalizações e altas taxas de morbimortalidade, sendo quase impossível a sua erradicação, ao evoluírem para a cronicidade. Globalmente, é notável o aumento nos índices de amostras não sensíveis aos carbapenêmicos e a múltiplos antimicrobianos, essenciais à terapêutica. Assim, avaliamos temporalmente a susceptibilidade aos antimicrobianos e a presença de amostras hipermutáveis (HPM) em P. aeruginosa de diferentes morfotipos, não sensíveis aos carbapenêmicos (PANSC), obtidas de pacientes FC com infecção pulmonar crônica, acompanhados em dois centros de referência no Rio de Janeiro. De 2007 a 2016, a análise retrospectiva, através dos resultados obtidos no teste de disco-difusão (TDD), permitiu selecionar amostras de PANSC incluídas neste trabalho. Usando os resultados obtidos no TDD, foi definida a susceptibilidade a outros antimicrobianos, bem como os fenótipos de resistência, multi-(MDR), extensivo-(XDR) e pandroga resistentes (PDR). Adicionalmente, determinou-se a concentração inibitória mínima (CIM) para imipenem (IPM), meropenem (MEM), doripenem (DOR) e polimixina (POL). Através de teste fenotípico, foi calculada a frequência de mutação espontânea e as amostras hipermutáveis foram caracterizadas. O sequenciamento de genoma total (SGT) foi realizado em seis amostras de diferentes morfotipos, incluindo uma variante fenotípica rara, a small colony variant (SCV). Essas amostras foram recuperadas em dois episódios de exacerbação do paciente. Foram investigadas a clonalidade, resistência a antimicrobianos e virulência. Das 143 amostras, de 18 pacientes (9 pediátricos e 9 adultos), os resultados do TDD apontaram taxas de não susceptibilidade superiores a 44% para gentamicina, amicacina, tobramicina e ciprofloxacina, e maiores de 30 % para POL. Pela determinação da CIM, quase a totalidade (96%) das amostras foram não sensíveis a IMP, seguidos de 56% para MEM e 44% para DOR. Analisando-se a distribuição dos valores da CIM50 e CIM90 nos dois grupos de pacientes, os valores para IMP foram maiores entre as amostras dos pacientes pediátricos, equivalendo a 32 µg/mL e 64 µg/mL, respectivamente. Cerca de 25%, 37% e 6% eram MDR, XDR e PDR, respectivamente. Aproximadamente 12% eram HPM, e mais da metade destas foram XDR. Após o SGT, as seis amostras, recuperadas do caso clínico foram classificadas em um novo sequence type (ST2744), com a presença de genes de resistência adquiridos blaPAO, blaOXA-50, aph(3')-Iib, fosA, catB7 e crpP, apresentando mutações em genes codificadores de porinas e bombas de efluxo. Entretanto, não foram observados marcadores genéticos clássicos exclusivos para os fenótipos SCV e HPM. Este é o primeiro relato de P. aeruginosa SCV na FC, no Brasil. A vigilância epidemiológica de P. aeruginosa é crucial para a conduta terapêutica, bem como para o sucesso da resposta do paciente e erradicação da infecção pulmonar, justificando o uso de técnicas fenotípicas e moleculares na detecção dos mecanismos de resistência e virulência desse microrganismo na FC.

Pseudomonas aeruginosa, a ubiquitous and versatile bacterium, can behave as an opportunistic pathogen, with strong adaptive capacity, due to multiple virulence and resistance factors. As a pulmonary infection pathogen in patients with cystic fibrosis (CF), it is related with poor prognosis, increased hospitalizations and high rates of morbidity and mortality, and the eradication is almost impossible, especially after chronicity. The increase rates of isolates non-susceptible to carbapenem and multiple antimicrobials, essentials to therapy, have been observed worldwide. Therefore, we assessed the antimicrobial susceptibility and the presence of hypermutability (HPM) in non-susceptible to carbapenem P. aeruginosa (PANSC) isolates from different morphotypes, obtained from CF patients with chronic pulmonary infection, followed at two reference centers in Rio de Janeiro. Using the results obtained by disk-diffusion test (DDT) between 2007 to 2016, we select 143 PANSC and susceptibility to other antimicrobials was defined, as well as the resistance phenotypes, multi- (MDR), extensive- (XDR) and pandrug resistant (PDR). Additionally, the minimum inhibitory concentration (MIC) for imipenem (IPM), meropenem (MEM), doripenem (DOR) and polymyxin (POL) was determined. Hypermutable isolates were characterized by determination of mutation frequency. Whole genome sequencing (WGS) was performed in six morphotypes isolates, including the small colony variant (SCV), a rare variant phenotype. These isolates were recovered in two exacerbation episodes. Clonality, antimicrobial resistance and virulence were investigated. Of the total (143 isolates) isolated from 18 patients (9 pediatric and 9 adults), non-susceptibility rates above than 44% for gentamicin, amikacin, tobramycin and ciprofloxacin, and more than 30% for POL were observed. Almost all (96%) of the isolates were non-susceptible to IPM by MIC determination, followed by 56% for MEM and 44% for DOR. MIC50 (32 µg/mL) and MIC90 (64 µg/mL) rates for IPM were higher among pediatric patient isolates and 25%, 37% and 6% were MDR, XDR and PDR, respectively. 12% of all isolates were classified as HPM and more than half were categorized as XDR. Using WGS, the six isolates recovered from the clinical case, were identified as a new sequence type (ST2744). Acquired resistance genes blaPAO, blaOXA-50, aph (3')-Iib, fosA, catB7 and crpP and mutations in encoding genes for porins and efflux pumps, was annotated. None exclusive classic genetic markers related to SCV and HPM phenotypes were not observed. This is the first Brazilian report of P. aeruginosa SCV in CF. Our results highlight the importance of epidemiological surveillance in P. aeruginosa. The application of phenotypic and molecular techniques to investigate resistance and virulence mechanisms, can contribute to therapeutic success in CF.

Antibacterial activity of Cinnamomum cassia L. essential oil in a carbapenem- and polymyxin-resistant Klebsiella aerogenes strain

Abstract INTRODUCTION: Essential oils can serve as novel sources of antibiotics for multidrug-resistant bacteria. METHODS: The multidrug-resistance profile of a Klebsiella aerogenes strain was assessed by PCR and sequencing. The antibacterial activity of Cinnamomum cassia essential oil (CCeo) against K. aerogenes was assessed by broth microdilution and time-kill methods. RESULTS: K. aerogenes showed high antibiotic resistance. The genes bla KPC-2, ampC, bla CTX-M-15, bla OXA-1, and bla TEM were present. CCeo exhibited an inhibitory effect with a minimum inhibitory concentration of 17.57 μg/mL. CONCLUSIONS: The antibacterial activity of CCeo makes it a potential candidate for treating carbapenem- and polymyxin-resistant K. aerogenes strains.

Non-clonal occurrence of pmrB mutations associated with polymyxin resistance in carbapenem-resistant Klebsiella pneumoniae in Brazil

BACKGROUND Polymyxins are currently used as a "last-line" treatment for multidrug-resistant Gram-negative infections. OBJECTIVES To identify the major mechanisms of resistance to polymyxin and compare the genetic similarity between multi-drug resistant Klebsiella pneumoniae strains recovered from inpatients of public hospitals in the Mid-West of Brazil. METHODS 97 carbapenems non-susceptible K. pneumoniae were studied. β-lactamases (bla OXA-48, bla KPC, bla NDM, bla CTX-M, bla SHV, bla TEM, bla IMP, bla VIM) and mcr-1 to mcr-5 genes were investigated by polymerase chain reaction (PCR). Mutations in chromosomal genes (pmrA, pmrB, phoP, phoQ, and mgrB) were screened by PCR and DNA sequencing. Clonal relatedness was established by using pulsed-field gel electrophoresis and multilocus sequence typing. FINDINGS K. pneumoniae isolates harbored bla KPC (93.3%), bla SHV (86.6%), bla TEM (80.0%), bla CTX-M (60%) genes. Of 15 K. pneumoniae resistant to polymyxin B the authors identified deleterious mutations in pmrB gene, mainly in T157P. None K. pneumoniae presented mcr gene variants. Genetic polymorphism analyses revealed 12 different pulsotypes. MAIN CONCLUSIONS Deleterious mutations in pmrB gene is the main chromosomal target for induction of polymyxin resistance in carbapenem-resistant K. pneumoniae in public hospitals in the Mid-West of Brazil.

Resistencia plasmídica a colistin por el gen mcr-1 en Enterobacteriaceae en Paraguay / Plasmid-Mediated Colistin Resistance Gene mcr-1 in Enterobacteriaceae in Paraguay

La resistencia a las polimixinas mediada por plásmidos (gen mcr-1) representa una amenaza para la salud pública, puesto que colistina es utilizada en la práctica médica como una de las últimas alternativas para el tratamiento de gérmenes multiresistentes. Este estudio describe la circulaciónde cepas de Enterobacterias que portan este gen de resistencia, aisladas de pacientes hospitalizados, así como también de la comunidad. Los hallazgos de la Red de Vigilancia de la Resistencia a los Antimicrobianos-Paraguay fueron de casi el 5 % (4,7) en cepas remitidas con criterio de sospecha, siendo las especies involucradas Escherichiacoli, Klebsiella pneumoniae y Salmonella Schwarzengrund. Además, por métodos moleculares se confirmaron en todas ellas la portación de otros genes de resistencia (KPC, CTX-M, Qnr B, Qnr S, aac (6`)-Ib-cr) asociados al mcr-1. Palabras claves: Enterobacterias, resistencia, colistina, mcr-1.

Resistance to polymyxins mediated by plasmids (mcr-1 gene) represents a threat to public health, since colistin is used in medical practice, as one of the last alternatives, for the treatment of multi-resistant germs. This study describes the circulation of strains of Enterobacteria that carry this resistance gene, isolated from hospitalized patients, as well as from the community. The findings of the Red de Vigilancia de la Resistencia a los Antimicrobianos­Paraguay were almost 5% (4.7) in strains submitted with suspicion criteria; the species involved being Escherichia coli, Klebsiella pneumoniae and Salmonella Schwarzengrund. In addition, molecular methods confirmed in all of them the carrying of other resistance genes (KPC, CTX-M, Qnr B, Qnr S, aac (6`)-Ib-cr) associated with mcr-1. Key words: Enterobacteria, resistance, colistin, mcr-1.

Lesão renal aguda associada ao uso de polimixinas em pacientes críticos / Acute kidney injury associated with the use of polymyxins in critically ill patients

Introdução: A Lesão renal aguda (LRA) é uma síndrome de alta incidência (23,2%) e mortalidade (23,0%), que acomete principalmente pacientes críticos, internados em unidades de terapia intensiva (UTI). A sepse é a principal causa de LRA (40,0%). A infecção por microrganismos multirresistentes exige o uso de agentes antimicrobianos potencialmente nefrotóxicos, como as polimixinas (Pmxs). Dentre elas, destaca-se a Pmx B e a colistina (Pmx E) utilizadas no controle de infecções por bacilos gram negativos (BGN). Objetivos: avaliar a incidência de LRA associada ao uso de Pmxs e identificar os fatores de risco para desenvolvimento de LRA associada ao uso de Pmxs. Métodos: Trata-se de um estudo transversal, retrospectivo, de abordagem quantitativa. A amostra foi composta por 1009 pacientes internados em UTI, provenientes de um banco de dados universal (BDU) organizado no período de abril a dezembro de 2012. Resultados: Foram incluídos 936 pacientes. A incidência geral de LRA na amostra foi de 43,1%, enquanto que para pacientes que receberam Pmxs foi de 87,0%. O principal fator de risco para LRA geral foi a pré existência de Doença Renal Crônica. Dentre os pacientes com LRA e que fizeram uso de Pmxs, a maioria era do sexo masculino (69,2%); 54,4±15,7 anos, internação do tipo clínica e com o maior tempo de internação em UTI, as características clínicas mais prevalentes foram o estado de choque (81,5%), a hipertensão arterial sistêmica (35,3%), o Diabetes Mellitus (20,0%) e a sepse (23,0%). Esse grupo apresentou maiores índices de gravidade SAPS II e LODS e o choque se confirmou como fator de risco nesse grupo. Conclusões: As Pmxs confirmaram-se como medicamento nefrotóxico em pacientes críticos (87%), tendo o choque como fator de risco.

Introduction: Acute kidney injury (AKI) is a syndrome of high incidence (23.2%) and mortality (23.0%), which affects mainly critically ill patients admitted to intensive care units (ICUs). Sepsis is the main cause of AKI (40.0%). Infection with multiresistant microorganisms requires the use of potentially nephrotoxic antimicrobial agents, such as polymyxins (Pmxs). Among them, Pmx B and colistin (Pmx E) are used to control gram-negative bacilli (GNB) infections. Objectives: to evaluate the incidence of AKI associated with the use of Pmxs and to identify the risk factors for the development of AKI associated with the use of Pmxs. Methods: It´s a cross-sectional, retrospective, quantitative approach The sample consisted of 1009 patients hospitalized in ICUs from a universal database (BDU) organized from April to December 2012. Results: A total of 936 patients were included. The overall incidence of AKI in the sample was 43.1%, whereas for patients receiving Pmxs it was 87.0%. The main risk factor for overall AKI was the pre-existence of Chronic Kidney Disease. Among the patients with AKI who used Pmxs, the majority were male (69.2%); 54.4 ± 15.7 years, hospitalization of the clinical type and with the longer ICU stay. The most prevalent clinical characteristics in the AKI and Pmx groups were shock state (81.5%), systemic arterial hypertension (35.3%), Diabetes Mellitus (20.0%) and sepsis (23.0% ). This group presented highest SAPS II and LODS severity indexes and the shock was confirmed as a risk factor. Conclusions: Pmxs were confirmed as nephrotoxic drugs in critical patients (87%), with shock as a risk factor.

Antimicrobial resistance in Enterobacteriaceae in Brazil: focus on ß-lactams and polymyxins

ABSTRACT During the last 30 years there has been a dissemination of plasmid-mediated β-lactamases in Enterobacteriaceae in Brazil. Extended spectrum β-lactamases (ESBL) are widely disseminated in the hospital setting and are detected in a lower frequency in the community setting. Cefotaximases are the most frequently detected ESBL type and Klebsiella pneumoniae is the predominant species among ESBL producers. Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae became widely disseminated in Brazil during the last decade and KPC production is currently the most frequent resistance mechanism (96.2%) in carbapenem resistant K. pneumoniae. To date KPC-2 is the only variant reported in Brazil. Polymyxin B resistance in KPC-2-producing K. pneumoniae has come to an alarming rate of 27.1% in 2015 in São Paulo, the largest city in Brazil. New Delhi metallo-β-lactamase was detected in Brazil in 2013, has been reported in different Brazilian states but are not widely disseminated. Antimicrobial resistance in Enterobacteriaceae in Brazil is a very serious problem that needs urgent actions which includes both more strict adherence to infection control measures and more judicious use of antimicrobials.

Induction and nosocomial dissemination of carbapenem and polymyxin-resistant Klebsiella pneumoniae

Polymyxins are antimicrobial agents capable of controlling carbapenemase-producing Klebsiella pneumoniae infection.

Efficacy of polymyxins in the treatment of carbapenem-resistant Enterobacteriaceae infections: a systematic review and meta-analysis

In recent years, carbapenem-resistant Enterobacteriaceae has become endemic in many countries. Because of limited treatment options, the abandoned "old antibiotics", polymyxins, have been reintroduced to the clinic. To evaluate the clinical efficacy of polymyxins in the treatment of infections caused by carbapenem-resistant Enterobacteriaceae, we systemically searched the PubMed, Embase, and Cochrane Library databases and analyzed the available evidence. The Preferred Reporting Items for Systematic reviews and Meta-Analysis statement were followed, and the I2 method was used for heterogeneity. Nineteen controlled and six single-arm cohort studies comprising 1086 patients met the inclusion criteria. For controlled studies, no significant difference was noted for overall mortality (OR, 0.79; 95% CI, 0.58-1.08; p = 0.15), clinical response rate (OR, 1.24; 95% CI, 0.61-2.54; p = 0.55), or microbiolog- ical response rate (OR, 0.59; 95% CI, 0.26-1.36; p = 0.22) between polymyxin-treated groups and the control groups. Subgroup analyses showed that 28-day or 30-day mortality was lower in patients who received polymyxin combination therapy than in those who received monotherapy (OR, 0.36; 95% CI, 0.19-0.68; p < 0.01) and the control groups (OR, 0.49; 95% CI, 0.31-0.75; p < 0.01). The results of the six single-arm studies were in accordance with the findings of controlled studies. One controlled and two single-arm studies that evaluated the occurrence of nephrotoxicity reported a pooled incidence rate of 19.2%. Our results suggest that polymyxins may be as efficacious as other antimicrobial therapies for the treatment of carbapenem-resistant Enterobacteriaceae infection. Compared to polymyxin monotherapy, combination regimens may achieve lower 28-day or 30-day mortality. Future large-volume, well-designed randomized control trials are required to determine the role of polymyxins in treating carbapenem-resistant Enterobacteriaceae infections.

Mecanismos de resistência antimicrobiana em pseudomonasaeruginosa / Mechanisms responsible for antimicrobial resistance in pseudomonas aeruginosa

Pseudomonas aeruginosa é uma bactéria de grande importância para indivíduos imunocomprometidos. No Brasil, ela é um dos principais agentes em infecções hospitalares e pode provocar diversos tipos de processos clínicos. Atualmente, um dos maiores desafios em infecções provocadas por P. aeruginosa é a resistência apresentada diante de inúmeros antimicrobianos. Além da resistência intrínseca de P.aeruginosa, essa bactéria facilmente desenvolve mecanismos de resistência adicionais, através de mutações e da aquisição de elementos genéticos móveis, por exemplo. Dessa forma, P. aeruginosa é considerada um patógeno multirresistente, o que limita as alternativas terapêuticas capazes de combatê-lo. Portanto, compreender osmecanismos que levam a essa resistência é de extrema importância para enfrentar as infecções por P. aeruginosa.

Pseudomonas aeruginosa is a bacterium of great importance forimmunocompromised individuals. In Brazil, it is one of the leadingcauses of hospital infections and can cause many types of infections.Currently, one of the biggest challenges in infections caused by P.aeruginosa is the resistance presented against numerousantimicrobials. In addition to the intrinsic resistance of P. aeruginosa,inherent in the species, this bacterium easily acquire additionalmechanisms of resistance via mutation and acquisition of mobilegenetic elements, for example. Accordingly, P. aeruginosa isconsidered a multidrug-resistant pathogen, which limits thetherapeutic alternatives able to fight it. Therefore, understanding themechanisms that lead to this resistance is of utmost importance totackle infections by P. aeruginosa.

Caracterização clínica, microbiológica e molecular e tratamento de infecções por enterobactérias resistentes aos carbapenêmicos / Clinical, microbiology and molecular characterization and treatment of infections with carbapenem-resistant Enterobacteriaceae

Introdução: Infecções por Enterobactérias resistentes aos carbapenêmicos (ERC), em especial produtoras de Klebsiella pneumoniae carbapenamase tipo KPC hoje são endêmicas em diversas regiões do mundo, seu tratamento é ainda um grande desafio em particular de isolados resistentes à polimixina. Objetivos: Descrever as características clínicas, microbiológicas e moleculares das infecções por ERC. Método: Estudo de coorte prospectiva, realizado no Hospital Universitário de Londrina, Paraná, Brasil, entre março de 2011 a dezembro de 2012. Foram acompanhados pacientes >= 18 anos, que apresentaram infecção por ERC. Dados demográficos e clínicos como idade, sexo, diagnóstico à admissão e presença de co-morbidades de acordo com critérios de Charlson, internação em Unidade de Terapia intensiva e scores APACHE e SOFA desses pacientes, colonização prévia por ERC, cirurgia prévia à infecção, diálise, uso prévio de antimicrobianos e sítio de infecção foram coletados. Foram avaliados os antimicrobianos utilizados para tratamento das infecções por mais de 48 horas nos seguintes pontos: monoterapia ou terapia associada, tempo de início (menor e maior que 12 horas). A identificação do agente foi realizada por método automatizado (Vitek II - bioMerieuxR) e a concentração inibitória mínima dos antibióticos por técnica de microdiluição em caldo, pesquisa de gene blaKPC pela técnica de Polimerase Chain Reaction e sinergismo entre drogas utilizadas em tratamento combinado por meio do método Time Kill. A clonalidade, por Pulsed Field gel eletroforese e analisada por dendograma pelo Bionumerics. Foram realizadas análise bivariada e regressão logística multivariada com técnica de Forward Stepwise para detectar fatores de risco para resistência a polimixina e mortalidade. O nível de significância adotado foi de 5%, utilizando os programas Epi Info 7.0 e SPSS. Resultados: No período de estudo, 127 pacientes apresentaram infecções por ERC, idade média de 55,7 (± 18) anos e 88 (69.3%) do...

Introduction: Infections due to Carbapenem resistant Enterobacteriaceae (CRE), particularly Klebsiella pneumoniae producing carbapenemase type KPC, have been endemic in several regions around the world. Their treatment remains a major challenge, particularly for isolates resistant to polymyxin. Objectives: To describe the clinical, microbiological and molecular characteristics of infections by CRE. Methods: Prospective cohort conducted at the University Hospital of Londrina, Paraná, Brazil, from March 2011 to December 2012. All hospitalized patients >= 18 years old who developed infection by CRE were followed until death or discharge. We collected and analyzed the following clinical data: age, sex, diagnosis at admission, presence of comorbidities according to the Charlson criteria, admission in Intensive Care Unit, APACHE and SOFA scores, previous colonization by CRE, previous surgery, dialysis, prior antibiotic use and infection site; furthermore, we also evaluated the time between the blood culture collect and the first antimicrobial dose administration (start time - smaller or longer than 12 hours) as well as whether the treatment was monotherapy or combine therapy for more than 48 hours. The microbiological identification was performed by automated method (Vitek II - bioMerieuxR) and the minimum inhibitory concentration of antibiotics by broth microdilution technique, research blaKPC gene by the technique of Polymerase Chain Reaction and synergism between the drugs used in the combination therapy by Time Kill method. The clonality was carried out by pulsed-field gel electrophoresis and analyzed by dendrogram by BioNumerics. Bivariate analyses and multivariate logistic regression with forward stepwise technique were performed to detect risk factors for resistance to polymyxin and mortality. The level of significance was 5%, using Epi Info 7.0 and SPSS programs. Results: During the study period, 127 patients developed infections by CRE,...

Eficacia, tolerancia y seguridad de una combinación de metronidazol, miconazol, centella asiática, polimixina y neomicina en cápsula blanda para uso vaginal en el tratamiento de la vaginosis bacteriana / Efficacy, tolerability, and safety of a combination including metronidazole, miconazole, Gotu kola, polymixin, and neomycin in soft vaginal capsules for the treatment of bacterial vaginosis

Introducción: La vaginosis bacteriana (VB) es un síndrome polimicrobiano, en la cual la flora dominante de lactobacilos normales es sustituida por una flora polimicrobiana. La prevalencia de VB en Perú varía entre 27 y 43,7%. El Centro de Control y Prevención de Enfermedades (DCD) sugiere el tratamiento de VB en mujeres sintomáticas con metronidazol oral/gel o clindamicina crema. Se planteó en el presente estudio evaluar la eficacia, tolerancia y seguridad de la combinación de metronidazol, miconazol, centella asiática, polimixina y neomicina en cápsula blanda para el tratamiento de VB. Material y Métodos: El presente estudio de tipo abierto, observacional, prospectivo, permitió evaluar la eficacia, tolerancia y seguridad en la aplicación de la combinación de metronidazol, miconazol, centella asiática, polimixina y neomicina en cápsula blanda. Resultados: Se incluyó a 61 pacientes con edad promedio de 29.28 años (rango 18-48) de las cuales 93,4% tenía historia previa de flujo vaginal anormal. Se realizaron dos visitas durante el estudio, la primera para diagnóstico e inicio de tratamiento y la segunda de control post tratamiento. Tres pacientes no tuvieron segunda visita y 8 no tenían registrada toda la información para definir la respuesta terapéutica. La segunda visita se realizó a los 21 días en promedio. Los principales signos y síntomas en la primera visita de diagnóstico fueron flujo vaginal (100,0%), disconfort vaginal (85,2%), dispareunia (70,5%) y dolor abdominal bajo (57,4%), las cuales disminuyeron en forma significativa (p<0,05) a la segunda visita post tratamiento. La prueba de aminas resultó positiva en el 93,4% de los casos en la primera visita y en el 15,5% de los casos en la segunda visita (p<0,05). De la población inicial de estudio, solo 53 mujeres son evaluables para eficacia terapéutica...

Introduction: Bacterial vaginosis (BV) is a polymicrobial syndrome, in which the normal dominant flora consisting in Lactobacillus is replaced by polymicrobial flora. The prevalence of BV in Peru varies between 27 and 43.7%. The Centers for Disease Control and Prevention suggest therapy for BV in symptomatic women should include oral/gel metronidazole or clindamycin cream. We proposed in this study to evaluate the efficacy, tolerability and safety of the combination of metronidazole, miconazole, Gotu kola (Centella asiatica), polymixin, and neomycin in soft capsules, for the treatment of BV. Material and Methods: This investigation was an open, observational, and prospective study, which allowed us to evaluate the efficacy, tolerability and safety of the aforementioned combined therapy administered in soft capsules. Results: The study included 61 patients with a mean age of 29.28 years (range, 18-48) and 93.4% had a history of abnormal vaginal discharge. Two visits took place during the study, the first for making the diagnosis and initiating therapy, and the second was the post-treatment control. Three patients did not have a second visit and 8 did not record all the information required to define the therapeutic response. The second visit took place after 21 days on average. The main signs and symptoms at the first visit were vaginal discharge at diagnosis (100.0%), vaginal discomfort (85.2%), dyspareunia (70.5%) and lower abdominal pain (57.4%), which were significantly reduced (p <0.05) in the second visit after treatment. The amine test was positive in 93.4% of cases in the first visit and in 15.5% of cases in the second visit (p <0.05). From the initial population in the study, only 53 women are evaluable for efficacy. An overall response rate in 44 women (83.02%) was achieved with the soft capsule combination treatment. Adverse events were reported in only one case...

Avaliação da solução de clorexidina 2 e medicamentos sobre Escherichiacoli e sua endotoxina em canais radiculares / Evaluation of 2 chlorhexidine solution and medicaments on Escherichia coli and endotoxins in root canals

A proposta deste estudo foi avaliar a efetividade da solução de clorexidina 2% e medicações intracanais sobre Eschericha coli e endotoxina em canais radiculares. Os canais radiculares de 48 dentes unirradiculados foram contaminados com E. coli por 14 dias, instrumentados com solução de clorexidina 2% e divididos em 3 grupos de acordo com a medicação intracanal (MIC) utilizada: pasta de Ca(OH)2, polimixina B, Ca(OH)2 + clorexidina gel 2% (CLX). No grupo controle foi utilizada somente solução fisiológica. Foram realizadas coletas do conteúdo do canal radicular imediatamente após a instrumentação (S1), após 7 dias da instrumentação (S2), imediatamente após 14 dias da ação da MIC (S3) e 7 dias após remoção da MIC (S4). Para todas as coletas foram realizados os seguintes testes: a) análise microbiológica; b)quantificação de endotoxina pelo teste cromogênico do lisado de amebócitos do Limulus. Os resultados foram analisados pelo teste de ANOVA e Dunn (5%). Na amostra S2 a sol. CLX 2% apresentou melhores resultados em relação à solução fisiológica. Na amostra S3 houve diferença estatística do Ca(OH)2 + CLX em relação ao Ca(OH)2 e polimixina B. Na amostra S4 não houve diferenças estatísticas significantes entre os grupos. Conclui-se que somente as medicações intracanais são capazes de diminuir significativamente a quantidade de endotoxinas.

The aim of this study was to evaluate the effectiveness of the 2% chlorhexidine solution and medications on Eschericha coli and endotoxin in root canals. The root canals of 48 single-rooted teeth were contaminated with E. coli for 14 days, instrumented with 2% chlorhexidine solution and divided into 3 groups according to the intracanal medication (ICM) used: Ca(OH)2 paste, polymyxin B (PB), Ca(OH)2 + 2% chlorhexidine gel (CLX). The control group it was only used physiological solution. Samples of the root canal content were collected immediately after PBM (S1), at 7 days after PBM(S2), immediately after 14 days of ICM activity (S3), and 7 days after removal of ICM (S4). The following aspects wereevaluated for all collections: a) antimicrobial activity; b) quantification of endotoxin by the Limulus amebocyte lysate Test. The results were analyzed by ANOVA and Dunn (5%) statistical tests. In the S2 sample the 2% CLX presented better resulted in relation to the physiological solution. In the S3 sample the Ca(OH)2 was statistically different from Ca(OH)2 and polymyxin B. In the S4 sample it did not have significant statistical differences between the groups. It was conclude that only the intracanals medications are capable to reduce the amount of endotoxins significantly.

Polimixinas: revisão com ênfase na sua nefrotoxicidade / Polymyxins: review with emphasis on nephrotoxicity

As polimixinas são antibióticos polipeptídeos com potente ação sobre várias bactérias gram-negativas. O seu uso foi praticamente abandonado entre 1970 e 1980, em virtude do aparecimento de drogas com menor toxicidade. Com o aparecimento de bactéria gram-negativas multirresistentes, principalmente em pacientes internados em unidades de terapia intensiva, e a ausência de novos antimicrobianos para combater esses patógenos, renovou-se o interesse pelas polimixinas nos últimos anos. O principal efeito adverso desta classe de antibióticos é a nefrotoxicidade. Atualmente, somente as polimixinas B e E são utilizadas na prática clínica. A polimixina E é conhecida como colistina e utilizada na forma de colestimetato de sódio com o intuito de reduzir sua nefrotoxicidade, sendo o composto mais utilizado e mais estudado. Não existem dados consistentes sobre a prevalência de leão renal associada ao uso das polimixinas ou sobre os fatores de risco para desenvolvimento de nefrotoxicidade desses antibióticos. A proposta deste artigo é rever os principais aspectos de farmacodinâmica das polimixinas, prover um melhor entendimento dos seus mecanismos de nefrotoxicidade e comparar as diferentes prevalências de lesão renal descritas com o uso desta classe de antibióticos.

Polymyxins are polypeptide antibiotics with strong action against Gram-negative bacteria. Their use was almost halted between 1970 and 1980 due to the launching of less toxic compounds. The emergence of multiresistant Gram-negative bacterial strains, mainly in patients hospitalized in intensive care units, and the absence of new antimicrobials effective against these pathogens, renewed interest in polymyxins in recent years. The major adverse effect of this class of antibiotics is nephrotoxicity. Currently, only polymyxins B and E are used in clinical practice. Polymyxin E, the compound more employed and studied, is known as colistin and is used in the form of sodium colistimethate, for the purpose of reducing its nephrotoxicity. There is no consistent data about prevalence of renal injury associated with use of the polymyxins or about the risk factors to develop nephrotoxicity with these antibiotics. The aim of this manuscript is to review the main aspects of polymyxin pharmacodynamics, to provide a better understanding about the mechanism of renal injury associated with them and to compare the different prevalences of renal injury described with the use of these antibiotics.

Perfil das pneumonias associadas á ventilação mecãnica na Unidade de Terapia Intensiva Geral do Hospital Universitário Evangélico de Curitiba no período de maio a dezembro de 2006 / Ventilator-ssociated Pneumonia Profile on Hospital Universitario Evangélico de Curitiba's General Intensive Care Unit in the period from may to december of 2006

Pneumonia associada à ventilação mecânica (PAVM) é um tipo de pneumonia hospitalar que ocorre após 48 horas de ventilação mecânica, sendo a infecção nosocomial mais frequente nas unidades de terapia intensiva(UTI). Este estudo objetiva estabelecer a preval~encia das PAVM na UTI geral do Hospital Universitário Evangélico de Curitiba (HUEC), definir seu perfil microbiológico, estabelecer possíveis fatores de risco e conhecer as principais sensibilidades aos antimicrobianos das mais frequentes bactérias causadoras da PAVM. Estudo caso-controle realizado na UTI geral do HUEC no período de maio a dezembro de 2006. Os dados referentes à frequ~encia de bactérias isoladas em culturas a partir do lavado broncoalveolar, antibiogramas e possíveis fatores de risco foram coletados em tabelas padronizadas no Microsoft Excel. Procedeu-se com a análise estatística utilizando o teste de Quiquadrado adotando-se p menor que 0,05, cálculo do Odds Ratio e intervalo de confiança. Cinquenta e tres pacientes desenvolveram PAVM com tempo médio necessário para o seu desenvolvimento de 12,43 dias. A idade média dos pacientes do grupo-caso foi de 46,81 anos. O coeficiente de preval~encia de PAVM na UTI geral do HUEC foi de 13,94 por cento. Pseudomonas aeruginosa foi o agente etiológico mais prevalente perfazendo um total de 32,89 pr cento dos casos. O uso prévio de antibióticos mostrou ser um possível fator de risco com diferença significativa entre os grupos-caso e controle e a Pseudomonas aeruginosa foi sensível à polimixina em 100 por cento dos casos testados.

Toxicidade de polimixina B em células LLC-PK1 e a enzima heme oxigenase-1 / Polymyxin B toxicity in LLC-PK1 cells and the heme oxygenase-1 enzyme

Na lesão renal aguda, os mecanismos de defesa atuam como "genes protetores", como a proteína heat shock 32 (HSP 32), também conhecida como heme oxigenase-1 (HO-1). A polimixina B (PmxB) é um antimicrobiano nefrotóxico. O objetivo deste estudo foi caracterizar a participação da enzima HO-1 na toxicidade da PmxB em células LLC-PK1. As células foram submetidas aos seguintes tratamentos: Controle (CTL- 0µM); Hemin (indutor de HO-1, 25µM); Hemin II (250 M), Protoporfirina de zinco (ZnPP - inibidor de HO-1, 10 M,); Nitro-L-arginina-metilester (L-NAME - inibidor de iNOS, 0,1mM); PmxB (375µM); PmxB + Hemin (25µM de Hemin uma hora antes da PmxB); PmxB + ZnPP (10 M de ZnPP uma hora antes da PmxB); PmxB + Hemin + L-NAME (25 M de Hemin e 0,1mM de L-NAME uma hora antes da PmxB). Os grupos foram avaliados em 24 e 72 horas. Foram analisados os seguintes parâmetros: desidrogenase láctica (DHL), peroxidação lipídica (MDA), expressão gênica da HO-1 por RT-PCR, síntese protéica da HO-1 por imunofluorescência, óxido nítrico (NO) pelo método de Griess e expressão protéica da HO-1 e da iNOS por western blotting. Os resultados mostraram que a PmxB elevou o DHL com aumento dos níveis de MDA. O Hemin e a ZnPP elevaram as variáveis DHL, MDA e óxido nítrico (NO). O indutor de HO-1 incrementou a expressão protéica da HO-1 e da iNOS. A PmxB se confirmou como citotóxica e a HO-1 intensificou a lesão por mecanismos oxidativos. O efeito da HO-1 na lesão celular parece ser mediado pelo NO.

In the acute kidney injury, the mechanisms of defense act as "protector genes", as the protein heat shock 32 (HSP 32), also known as heme oxygenase-1 (HO-1). The polymyxin B (PmxB) is a nephrotoxic antimicrobial. The aim of this study was to distinguish the role of the HO-1 enzyme in the PmxB toxicity in LLC-PK1 cells. The cells were submitted to the following treatments: Control (CTL- 0µM); Hemin (inhibitor of HO-1, 25µM); Hemin II (250 M), Zinc protoporphyrin (ZnPP - inhibitor of HO-1, 10 M,); NG-nitro-L-arginine methyl ester (L-NAME - inhibitor of iNOS, 0,1mM); PmxB (375µM); PmxB + Hemin (25µM of Hemin one hour before the PmxB); PmxB + ZnPP (10 M of ZnPP one hour before the PmxB); PmxB + Hemin + L-NAME (25 M of Hemin and 0,1mM of L-NAME one hour before the PmxB). All groups were evaluated in 24 and 72 hours. The following parameters were analysed: lactate dehydrogenase (LDH), lipid peroxidation (MDA), genic expression of HO-1 by RT-PCR, protein syntesis of HO-1 by immunofluorescence, nitric oxide (NO) by Griess method and protein expression of HO-1 and of iNOS by western blotting. The results showed that PmxB increased the LDH and the levels of MDA. Hemin and ZnPP also increased the LDH variables, MDA and nitric oxide (NO). The inducer of HO-1 improved the protein expression of HO-1 and of iNOS. The PmxB was confirmed as a cytotoxic and the HO-1 intensified the failure by oxidative mechanisms. The effect of HO-1 in the cell injury seemed to be mediated by NO.

A randomized double-blind clinical trial of the effect of non-absorbable oral polymyxin on infants with severe infectious diarrhea

The present study evaluated the effect of non-absorbable oral polymyxin on the duodenal microflora and clinical outcome of infants with severe infectious diarrhea. Polymyxin was chosen because classic enteropathogenic Escherichia coli was more sensitive to this antibiotic. Twenty-five infants were randomly assigned to a 7-day treatment with oral polymyxin (2.5 mg/kg in 4 daily doses) or placebo. Duodenal and stool cultures were performed before and after the treatment. Five patients were excluded during the study because of introduction of parental antibiotic therapy due to clinical sepsis (N = 3) or rapid clinical improvement (N = 2). In the polymyxin group, small bowel bacterial overgrowth occurred in 61.5 percent of the cases (8/13) before treatment and in 76.9 percent (10/13) after treatment. In the placebo group these values were 71.4 percent (5/7) and 57.1 percent (4/7), respectively. By the 7th day, clinical cure was observed in 84.6 percent of the cases (11/13) in the polymyxin group and in 71.4 percent (5/7) in the placebo group (P = 0.587). Considering all 25 patients included in the study, clinical cure occurred on the 7th day in 12/14 cases (85.7 percent) in the polymyxin group and 6/11 cases (54.5 percent) in the placebo group (P = 0.102). Clinical sepsis occurred in 3/11 (27.3 percent) of the patients in the placebo group and in none (0/14) in the polymyxin group (P = 0.071). Oral polymyxin was not effective in reducing bacterial overgrowth or in improving the clinical outcome of infants hospitalized with severe infectious diarrhea. Taking into account the small sample size, the rate of cure on the 7th day and the rate of clinical sepsis, further studies with greater number of patients are necessary to evaluate these questions.

A cólera no Estado do Rio Grande do Norte--Brasil--perfil sorológico e de sensibilidade do Vibrio cholerae a diferentes antimicrobianos / Cholera in Rio Grande do Norte State--Brazil: sorology and sensitivity of Vibrio cholerae to different antimicrobials

PURPOSE: The emergence of multiple resistance to antimicrobials in Vibrio cholerae isolated in the state of Ceará, Brazil, alerted researchers in this area to the sensitivity to antimicrobials of strains isolated in Rio Grande do Norte (RN), Brazil. METHODS: One hundred and four strains of V. cholerae of human origin, isolated by Laboratório Central de Saúde Pública Dr. Almino Fernandes, were serologically typified and evaluated for in vitro sensitivity to eight antibiotics belonging to different groups (polymyxine, tetracycline, chloramphenicol, nitrofurantoin, sulphazotrin, pefloxacine, erythromycine, ampicillin). The strains were collected from patients suspected of contracting choleric diarrhea in the year 1999, in Natal/RN/Brazil. RESULTS: From the sample total, 100 were identified as V. cholerae, serogroup O:1, biotype El Tor, with 99 (95.3%) belonging to serovar Ogawa and only 1 (0.9%) to serovar Inaba. The 4 remaining were characterized as non O:1 V. cholerae, with 3 (2.9%) biochemically identified as Heiberg type I and 1 (0.9%) as type II. All the V. cholerae serogroup O:1 strains were sensitive to tetracycline, chloramphenicol, sulphazotrin, pefloxacine, erythromycine and resistant to polymyxine. In relation to nitrofurantoin, only 1 was sensitive. Only 1 was resistant to ampicillin. The non O:1 V. cholerae strains were resistant to polymyxine. CONCLUSIONS: The results showed sensitivity in 100% of the V. cholerae serogroup O:1 strains to tetracycline, an elective drug in the treatment of cholera, and an absence of multiple resistant strains in our environment. An interesting finding was the frequency of serovar Ogawa in 1999, considering the greater incidence of serovar Inaba in other years of cholera outbreaks in RN.