Vanessa Bley Ribeiro

Dissemination of blaKPC-2 by the Spread of Klebsiella pneumoniae Clonal Complex 258 Clones (ST258, ST11, ST437) and Plasmids (IncFII, IncN, IncL/M) among Enterobacteriaceae Species in Brazil

ABSTRACT This article reports the spread of blaKPC-2 in the Sao Paulo and Rio de Janeiro states, facilitated by globally spread K. pneumoniae clonal complex 258 (CC258) clones (ST258, ST11, and ST437) and a diversity of plasmids (IncFII, IncN, and IncL/M, two untypeable plasmids carrying Tn4401a or Tn4401b) successfully disseminated among species of the Enterobacteriaceae (Enterobacter cloacae, Serratia marcescens, and Citrobacter freundii). It also constitutes the first description of sequence type 258 (ST258) in Brazil, which was associated with a nosocomial hospital outbreak in Ribeirao Preto city.

In Vitro Antioxidant, Anticoagulant and Antimicrobial Activity and in Inhibition of Cancer Cell Proliferation by Xylan Extracted from Corn Cobs

Xylan is one of most abundant polymer after cellulose. However, its potential has yet to be completely recognized. Corn cobs contain a considerable reservoir of xylan. The aim of this work was to study some of the biological activities of xylan obtained from corn cobs after alkaline extraction enhanced by ultrasonication. Physical chemistry and infrared analyses showed 130 kDa heteroxylan containing mainly xylose:arabinose: galactose:glucose (5.0:1.5:2.0:1.2). Xylan obtained exhibited total antioxidant activity corresponding to 48.5 mg of ascorbic acid equivalent/g of xylan. Furthermore, xylan displayed high ferric chelating activity (70%) at 2 mg/mL. Xylan also showed anticoagulant activity in aPTT test. In antimicrobial assay, the polysaccharide significantly inhibited bacterial growth of Klebsiella pneumoniae. In a test with normal and tumor human cells, after 72 h, only HeLa tumor cell proliferation was inhibited (p < 0.05) in a dose-dependent manner by xylan, reaching saturation at around 2 mg/mL, whereas 3T3 normal cell proliferation was not affected. The results suggest that it has potential clinical applications as antioxidant, anticoagulant, antimicrobial and antiproliferative compounds.

Emergence of NDM-1-producing Enterobacteriaceae in Porto Alegre, Brazil

OBJECTIVES To evaluate the emergence of New Delhi metallo-β-lactamase 1 (NDM-1)-producing Enterobacteriaceae isolates in Brazil. METHODS From April to October 2013, following the detection of the first NDM-1-producing isolate, a surveillance study was performed for the detection of blaNDM-1 among Enterobacteriaceae isolates with reduced susceptibility to carbapenems in 17 hospitals of Porto Alegre, Brazil. Real-time PCR was used to determine the presence of carbapenemase genes, which were further sequenced. Clonal relatedness was assessed by pulsed-field gel electrophoresis (PFGE). RESULTS A total of 1134 isolates were evaluated. blaNDM-1 was detected in 11 (0.97%) isolates: nine Enterobacter cloacae complex (eight belonging to a single clone recovered from two distinct hospitals and the other strain from a third hospital) and two Morganella morganii (belonging to a single clone recovered from one hospital). Most isolates presented high-level resistance to carbapenems. CONCLUSIONS NDM-1-producing Enterobacteriaceae have emerged rapidly in the hospitals of the Brazilian city where they were first detected. The emergence of NDM-1 in Brazil is of great concern, since it is a severe threat to antimicrobial therapy against Enterobacteriaceae in this country.

Detection of OXA-370, an OXA-48-related class D β-lactamase, in Enterobacter hormaechei from Brazil

Jorge L. M. Sampaio, Vanessa B. Ribeiro, Juliana Coutinho Campos, Franciéli P. Rozales, Cibele M. Magagnin, Diego R. Falci, Renato Cassol F. da Silva, Micheline G. Dalarosa, Daniela I. Luz, Fabiane J. Vieira, Laura C. Antochevis, Afonso Luis Barth, Alexandre P. Zavascki Departamento de Análises Clínicas e Toxicológicas—Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil; Microbiologia—Fleury Medicina e Saúde, São Paulo, Brazil; Laboratório de Pesquisa em Resistência Bacteriana—LABRESIS, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil; Programa de PósGraduação em Ciências Farmacêuticas, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Infection Control Service, Hospital Nossa Senhora da Conceição, Porto Alegre, Brazil; Infectious Diseases Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil; Department of Internal Medicine, Medical School, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

Evaluation of heteroresistance to polymyxin B among carbapenem-susceptible and -resistant Pseudomonas aeruginosa

One hundred and twenty-four Pseudomonas aeruginosa isolates were selected for antimicrobial susceptibility testing with anti-pseudomonal agents, MIC determination for polymyxin B and metallo-beta-lactamase detection (genes blaSPM, blaVIM-1, blaNDM-1 and blaIMP). According to the imipenem and/or meropenem susceptibility profile, a set of randomly selected isolates (12 isolates carbapenem-susceptible and 12 isolates carbapenem-resistant) were evaluated for heteroresistance to polymyxin B. Heteroresistance testing was performed by plating the isolates onto increasing concentrations of polymyxin B (from 0 to 8.0 mg l(-1)). The population analysis profile (PAP) was defined as the ratio of the number of colony-forming units on the plate with the highest concentration of polymyxin B at which bacterial growth occurred against the number of colony-forming units on the plate without antibiotic. Isolates presenting subpopulations that exhibited growth at polymyxin B concentrations ≥2 mg l(-1) were considered heteroresistant. Isolates containing subpopulations that grew at polymyxin B concentrations at least twice as high as the original MIC but <2 mg l(-1) were considered heterogeneous. Antimicrobial susceptibility testing results indicated a variable degree of susceptibility: high levels of resistance to gentamicin (30.6 %) and imipenem (29.0 %); low levels of resistance to aztreonam (1.6 %) and ciprofloxacin (4.8 %). All isolates were susceptible to polymyxin B: MIC50 and MIC90 were 1 mg l(-1) and 2 mg l(-1), respectively. Thirty-seven isolates (30 %) were carbapenem-resistant. Four isolates resistant to carbapenems were positive for blaIMP. There were no heteroresistant subpopulations in the carbapenem-susceptible group, but three isolates presented heterogeneous subpopulations. The PAP frequency ranged from 2.1×10(-4) to 6.9×10(-8). In the carbapenem-resistant group, one isolate was heteroresistant. Six isolates in this group presented heterogeneous subpopulations. In the resistant population, the PAP frequency ranged from 2.1×10(-7) to 2.6×10(-4). In this study, polymyxin B heteroresistance in P. aeruginosa was uncommon and occurred in only one carbapenem-resistant isolate, despite the fact that several isolates presented heterogeneous subpopulations with increased polymyxin B MICs.

Detection of blaKPC-2 in a carbapenem-resistant Kluyvera georgiana

Faculdade de Farmacia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Unidade de Microbiologia e Biologia Molecular, Servico de Patologia Clinica, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil; Infectious Diseases Service, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil; Infection Control Service, Hospital Sao Lucas da Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, Brazil; Faculdade de Ciencias Farmaceuticas, Universidade de Sao Paulo, Sao Paulo, Brazil; Microbiologia—Fleury Medicina e Saude, Sao Paulo, Brazil

Effect of cefepime dose on mortality of patients with Gram-negative bacterial bloodstream infections: a prospective cohort study

OBJECTIVES There are controversies regarding the association of cefepime therapy with increased mortality among patients with infections caused by Gram-negative bacteria (GNB). We evaluated the effect of cefepime on the mortality of patients with GNB bloodstream infections (BSIs). METHODS A prospective cohort study was conducted in adult patients with creatinine ≤1.5 mg/dL who received empirical therapy with cefepime for at least 48 h for BSIs caused by GNB. The outcome was hospital mortality. Potential clinical predictors, including a high-dose regimen (2 g every 8 h), were assessed. RESULTS One hundred and thirteen patients were included. Most (78.8%) isolates had low cefepime MICs (≤0.25 mg/L). The overall hospital mortality was 35.4% [25.6% (10/39) and 40.5% (30/74) in patients receiving high-dose and usual-dose cefepime, respectively (P = 0.17)]. In a Cox regression model adjusted for cefepime MIC and propensity score, a high-dose regimen was independently associated with lower mortality rates [adjusted hazard ratio (aHR) 0.41; 95% CI 0.18-0.91; P = 0.029] while presentation with severe sepsis or septic shock was independently associated with higher mortality rates (aHR 4.10; 95% CI 1.78-9.40; P = 0.001). A trend to lower mortality rates was also found in the subgroup analysis of patients who had not switched antibiotic during therapy after adjustment for the latter variables. CONCLUSIONS High-dose cefepime therapy was associated with lower mortality rates in patients with GNB BSIs, even for GNB with low cefepime MICs.

Detection of blaGES-5 in Carbapenem-Resistant Kluyvera intermedia Isolates Recovered from the Hospital Environment

Vanessa B. Ribeiro, Alexandre P. Zavascki, Franciéli P. Rozales, Mariana Pagano, Cibele M. Magagnin, Carolina S. Nodari, Renato Cassol Ferreira da Silva, Micheline G. Dalarosa, Diego R. Falci, Afonso L. Barth ‹Laboratório de Pesquisa em Resistência Bacteriana, Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil; Infectious Diseases Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas; Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Médicas, UFRGS, Porto Alegre, Brazil; Hospital Nossa Senhora da Conceição, Porto Alegre, Brazil

Molecular characterization of Klebsiella pneumoniae carbapenemase-producing isolates in southern Brazil.

Carbapenem-resistant Enterobacteriaceae have been frequently reported worldwide. They represent a serious concern because of the limited therapeutic options. The aim of this study was to investigate the molecular epidemiology of 14 Klebsiella pneumoniae carbapenemase (KPC) producers among 345 clinical isolates of Enterobacteriaceae with reduced susceptibility to carbapenems recovered from 11 separate hospitals in southern Brazil. The blaKPC-2 gene was detected in 14 isolates (4 %): six Enterobacter cloacae, five K. pneumoniae and three Serratia marcescens. Most of these isolates exhibited high-level resistance against β-lactams and ciprofloxacin, while the most active drugs were polymyxin B and amikacin. Genetic environment analysis, based on the classical Tn4401 structure, revealed six distinct platforms. Plasmids carrying blaKPC-2 were not typable and most were approximately 20 kb. Only KPC carbapenemases were found among the isolates studied, highlighting the local relevance of these enzymes in acquired resistance to carbapenems in Enterobacteriaceae. Our results contribute to the understanding of carbapenem resistance in Enterobacteriaceae and to the molecular characterization of KPC-2-producing isolates in Brazil.

Activity of Antimicrobial Combinations against KPC-2-Producing Klebsiella pneumoniae in a Rat Model and Time-Kill Assay

ABSTRACT This study evaluated the efficacy of tigecycline (TIG), polymyxin B (PMB), and meropenem (MER) in 80 rats challenged with Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae infection. A time-kill assay was performed with the same strain. Triple therapy and PMB+TIG were synergistic, promoted 100% survival, and produced negative peritoneal cultures, while MER+TIG showed lower survival and higher culture positivity than other regimens (P = 0.018) and was antagonistic. In vivo and in vitro studies showed that combined regimens, except MER+TIG, were more effective than monotherapies for this KPC-producing strain.