Renato Torres Gonçalves

The influence of carbapenem resistance on mortality in solid organ transplant recipients with Acinetobacter baumannii infection

BackgroundInfection with carbapenem-resistant Acinetobacter baumannii has been associated with high morbidity and mortality in solid organ transplant recipients. The main objective of this study was to assess the influence of carbapenem resistance and other potential risk factors on the outcome of A. baumannii infection after kidney and liver transplantation.MethodsRetrospective study of a case series of A. baumannii infection among liver and renal transplant recipients. The primary outcome was death associated with A. baumannii infection. Multivariate logistic regression was used to assess the influence of carbapenem resistance and other covariates on the outcome.ResultsForty-nine cases of A. baumannii infection affecting 24 kidney and 25 liver transplant recipients were studied. Eighteen cases (37%) were caused by carbapenem-resistant isolates. There were 17 (35%) deaths associated with A. baumannii infection. In unadjusted analysis, liver transplantation (p = 0.003), acquisition in intensive care unit (p = 0.001), extra-urinary site of infection (p < 0.001), mechanical ventilation (p = 0.001), use of central venous catheter (p = 0.008) and presentation with septic shock (p = 0.02) were significantly related to a higher risk of mortality associated with A. baumannii infection. The number of deaths associated with A. baumannii infection was higher among patients infected with carbapenem-resistant isolates, but the difference was not significant (p = 0.28). In multivariate analysis, the risk of A. baumannii-associated mortality was higher in patients with infection acquired in the intensive care unit (odds ratio [OR] = 34.8, p = 0.01) and on mechanical ventilation (OR = 15.2, p = 0.04). Appropriate empiric antimicrobial therapy was associated with significantly lower mortality (OR = 0.04, p = 0.03), but carbapenem resistance had no impact on it (OR = 0.73, p = 0.70).ConclusionThese findings suggest that A. baumannii-associated mortality among liver and kidney transplant recipients is influenced by baseline clinical severity and by the early start of appropriate therapy, but not by carbapenem resistance.

Digitally programmable switched current filters

A new design technique for switched current filters is presented. The basic element of the filter is a current mirror that employs MOS transistors and an operational amplifier. Programmability of the current mirror is obtained through MOSFET-only current dividers. User programmable analog functions in digital CMOS technology is the main envisaged application for the proposed technique.

Molecular characterization of BK polyomavirus subtypes in renal transplant recipients in Brazil

BK polyomavirus (BKV) is highly prevalent in the world population. Different reports indicate that BKV subtypes and subgroups present an uneven geographical distribution which might be correlated with human migration. However, there is a lack of data on the BKV subtype distribution in the South American population. The occurrence of BKV subtypes and subgroups detected in 51 kidney transplant recipients in Rio de Janeiro, Brazil is described. According to genetic studies, the population in this region descends mainly from European or African immigrants, with a relatively low genetic background from the Amerindians. By sequencing the VP1 region of BKV, subgroups Ib1 and Ia of subtype I were found in 34 (67%) and 15 (29%), respectively, of samples, while subtype II was present in 2 (4%) of the samples. Subtypes III and IV were not detected. Phylogenetic analysis indicated similarities between Brazilian BKV subgroup Ia and East African lineages; and subgroup Ib‐1 with Asian and North American lineages, while subtype II samples were similar to sequences from Japan and the UK. This is the first report that describes distribution of BKV subtypes in South America. The high prevalence of BKV subgroup Ia probably reflects the high proportion of African descendants in this population. On the other hand, the predominance of subgroup Ib‐1 and the absence of Ib‐2 in an area with a high proportion of European ancestry was unexpected. Further studies in South American populations are needed to provide a better understanding of the epidemiology of BKV in this region. J. Med. Virol. 83:1401–1405, 2011.

Urinary Tract Infections in Renal Transplant Recipients: Virulence Traits of Uropathogenic Escherichia coli

BACKGROUND Urinary tract infection (UTI) is the most common infectious complication after renal transplantation. Most infections are caused by uropathogenic Escherichia coli (UPEC). There are limited data on the prevalence of virulence traits among UPEC isolated from renal transplant recipients. This study compared the phenotypic and genotypic profiles of UPEC strains isolated from recipients with those from control patients. METHODS E coli isolates that caused UTI in recipients versus nonimmunosuppressed control patients were characterized according to phylogenetic group and the presence of urovirulence genes pap1/pap2; sfa1/sfa2; afa1/afa2; aer1/aer2; and cnf1/cnf2. RESULTS Thirty-six UPEC isolates from recipients and another 27 from control individuals were included in the study. The proportion of episodes of pyelonephritis in recipients (50%) versus control subjects (41%) was similar (P = .46). However, secondary bacteremia was observed only among recipients (n = 8; P < .001). There was no significant difference in the distribution of phylogenetic groups or the prevalence of analyzed virulence traits between UPEC isolated from the 2 groups. Nevertheless, strains associated with secondary bacteremia in recipients showed a higher prevalence of mannose-resistant hemagglutination (P = .013). CONCLUSION The phenotypic and genotypic characteristics of UPEC isolated from recipients were similar to those from control patients at a tertiary care center. Secondary bacteremia in recipients was associated with a higher prevalence of mannose-resistant hemagglutination.

A Qualitative Seminested PCR Assay as an Alternative to Urine Cytology for BK Polyomavirus Screening after Renal Transplantation

Objective: Polyomavirus-associated nephropathy (PVAN) is a major cause of graft dysfunction after kidney transplantation. Therefore, routine screening for BK polyomavirus (BKV) infection with urine cytology or quantitative PCR-based assays has been recommended. Although less expensive than quantitative tests, qualitative PCR assays are not recommended for screening based on the assumption that their diagnostic accuracy is inferior to urine cytology. However, studies comparing the performance of both methods are scarce. Methods: We compared the accuracy between a qualitative seminested PCR (snPCR) assay and urine cytology for the screening of BKV viruria in 104 renal transplant recipients. Results: The snPCR assay was more sensitive than cytology (100 and 61%, respectively), yielding better negative predictive value (100 vs. 90%). In 7 (39%) of the 18 PVAN cases, BKV infection was detected exclusively by snPCR. Although the specificity of snPCR (63%) was lower than cytology (74%), their positive predictive values were similar (36 vs. 33%, respectively). In ROC curve analysis, the accuracy of snPCR was significantly higher (p = 0.03). Conclusion: This qualitative snPCR assay was more accurate than urine cytology for the detection of BKV viruria in renal transplant patients.

Prevalence of occult hepatitis B virus infection in kidney transplant recipients

In this cross-sectional study, 207 hepatitis B surface antigen (HBsAg)-negative kidney transplant recipients were evaluated based on demographic and epidemiological data and on the levels of serological markers of hepatitis B virus (HBV) and hepatitis C virus infection and liver enzymes. Patients with HBV or human immunodeficiency virus infection were excluded. Sera were analysed for the presence of HBV-DNA. HBV-DNA was detected in two patients (1%), indicating occult hepatitis B (OHB) infection (the HBV-DNA loads were 3.1 and 3.5 IU/mL in these patients). The results of the liver function tests were normal and no serological markers indicative of HBV infection were detected. The prevalence of OHB infection was low among kidney transplant recipients, most likely due to the low HBsAg endemicity in the general population of the study area.

Immunosuppressants: implications in Orthodontics

INTRODUCTION: There are medications capable of affecting bone metabolism and the rate of tooth movement. Among these medications are the immunosuppressants, which act by repressing the action of T lymphocytes, however they can cause bone loss and consequently lead to osteoporosis. Osteoporosis is a common complication following kidney, heart, liver or lung transplantation. The immunosuppressant treatment for preventing organ rejection after transplantation, in general, includes glucocorticoids, cyclosporine, tacrolimus, and sirolimus. All these drugs can have jeopardizing effects on bone mineral homeostasis and consequently influence tooth movement. In recent years, however, the increasing use of immunosuppressants has raised questions about their effects on bone metabolism in patients undergoing orthodontic treatment. OBJECTIVE: The objective of this review study was to inform orthodontists about the influence of immunosuppressants on bone metabolism and tooth movement.

Avaliação de transplantes renais utilizando-se 99mTc-leucócitos mononucleares

A rejeicao aguda do enxerto renal deve ser diagnosticada precocemente, uma vez que a reversibilidade da rejeicao esta relacionada com a rapidez na qual o tratamento e iniciado. Os objetivos deste estudo foram: 1) estabelecer um metodo quantitativo para avaliacao da rejeicao e necrose tubular aguda (NTA) do rim transplantado; 2) determinar o papel em potencial da cintilografia com leucocitos mononucleares marcados com tecnecio-99m no diagnostico precoce da rejeicao do rim transplantado e no diagnostico diferencial da NTA. Cento e sessenta estudos cintilograficos foram realizados no primeiro e no quinto dia pos-operatorio em 80 pacientes transplantados. Celulas autologas foram utilizadas para marcacao. Imagens foram obtidas 30 minutos, 3 horas e 24 horas apos injecao de 444 MBq (12 mCi) das celulas marcadas. Houve captacao anormal das celulas marcadas em 27 de 31 casos de rejeicao e em seis de oito casos de NTA. Os resultados foram comparados com a clinica de cada paciente. Ultra-sonografias com Doppler detectaram 18 de 31 casos de rejeicao. A sensibilidade e a especificidade para rejeicao foram, respectivamente, de 87,1% e 100% para a cintilografia e 58,1% e 100% para a ultra-sonografia. Foram realizadas biopsias em oito pacientes, que mostraram sete rejeicoes e uma NTA. Os resultados sugerem que a cintilografia com leucocitos mononucleares marcados com tecnecio-99m pode ser util no diagnostico de rejeicao e diagnostico diferencial de NTA.

Evaluación de aterosclerosis en trasplantados renales mediante métodos no invasivos

BACKGROUND Endothelial dysfunction can be considered an early atherogenic event. OBJECTIVE To assess atherosclerosis in renal transplanted patients through the coronary calcium score, carotid duplex scan and brachial reactivity through ultrasonography. METHODS We assessed 30 renal transplanted male patients with stable renal function, with a mean age of 41.3 years. RESULTS The detection of the atherosclerotic load in this population was very significant when the brachial reactivity technique was used (86.7%); it was less frequent when based on the presence of carotid plaque (33.3%) or the coronary calcium score (20%). The carotid plaque was considered when the thickness was > 12 mm. The coronary calcium score was abnormal when > 80 according to the Agatston scale, being observed in a low percentage of patients (21.7%), possibly due to the fact that the tomography is not the ideal method to detect atherosclerosis in renal patients, as it does not differentiates intimal calcifications of the medial layer. The adequate clinical control, the low age range and the factors related to the time of pre-transplant dialysis or the anti-inflammatory effect of the post-transplant drugs can delay the onset of the calcifications. CONCLUSION The evaluation of the atherosclerotic load through the carotid duplex scan (33,3%) and the coronary calcium score (20%) was not frequent; there was no correlation with the high rate of endothelial dysfunction detection observed with the brachial reactivity assessment (86.7%).FUNDAMENTO: A disfuncao endotelial pode ser considerada um evento precoce da aterogenese. OBJETIVO: Avaliar a aterosclerose em transplantados renais atraves do escore de calcio coronariano, do duplex scan das carotidas e da reatividade braquial atraves do ultra-som. METODOS: Avaliamos trinta transplantados renais do sexo masculino com funcao renal estavel, idade media de 41,3 anos. RESULTADOS: A deteccao da carga aterosclerotica nesta populacao foi significativa quando utilizada a tecnica da reatividade braquial (86,7%), menos frequente baseando-se na presenca de placa carotidea (33,3%) ou no escore de calcio coronariano (20%). Placa carotidea foi considerada quando a espessura era superior a 12 mm. O escore de calcio coronariano foi anormal quando acima de oitenta pela escala de Agatston, sendo observado em um percentual baixo (21,7%) dos pacientes, possivelmente porque a tomografia pode nao ser o metodo ideal para detectar aterosclerose em doentes renais, por nao distinguir calcificacoes intimais da camada media. O controle clinico adequado, a baixa faixa etaria e fatores relacionados ao tempo de dialise pre-transplante ou ao efeito antiinflamatorio das drogas pos-transplante podem retardar o aparecimento das calcificacoes. CONCLUSAO: A avaliacao da carga aterosclerotica atraves do duplex scan das carotidas (33,3%) e do escore de calcio coronariano (20%) nao foi frequente, nao havendo correlacao com o elevado indice de deteccao de disfuncao endotelial observado com o exame da reatividade braquial (86,7%).

Evaluation of atherosclerosis in renal transplanted patients by non-invasive methods.

BACKGROUND Endothelial dysfunction can be considered an early atherogenic event. OBJECTIVE To assess atherosclerosis in renal transplanted patients through the coronary calcium score, carotid duplex scan and brachial reactivity through ultrasonography. METHODS We assessed 30 renal transplanted male patients with stable renal function, with a mean age of 41.3 years. RESULTS The detection of the atherosclerotic load in this population was very significant when the brachial reactivity technique was used (86.7%); it was less frequent when based on the presence of carotid plaque (33.3%) or the coronary calcium score (20%). The carotid plaque was considered when the thickness was > 12 mm. The coronary calcium score was abnormal when > 80 according to the Agatston scale, being observed in a low percentage of patients (21.7%), possibly due to the fact that the tomography is not the ideal method to detect atherosclerosis in renal patients, as it does not differentiates intimal calcifications of the medial layer. The adequate clinical control, the low age range and the factors related to the time of pre-transplant dialysis or the anti-inflammatory effect of the post-transplant drugs can delay the onset of the calcifications. CONCLUSION The evaluation of the atherosclerotic load through the carotid duplex scan (33,3%) and the coronary calcium score (20%) was not frequent; there was no correlation with the high rate of endothelial dysfunction detection observed with the brachial reactivity assessment (86.7%).FUNDAMENTO: A disfuncao endotelial pode ser considerada um evento precoce da aterogenese. OBJETIVO: Avaliar a aterosclerose em transplantados renais atraves do escore de calcio coronariano, do duplex scan das carotidas e da reatividade braquial atraves do ultra-som. METODOS: Avaliamos trinta transplantados renais do sexo masculino com funcao renal estavel, idade media de 41,3 anos. RESULTADOS: A deteccao da carga aterosclerotica nesta populacao foi significativa quando utilizada a tecnica da reatividade braquial (86,7%), menos frequente baseando-se na presenca de placa carotidea (33,3%) ou no escore de calcio coronariano (20%). Placa carotidea foi considerada quando a espessura era superior a 12 mm. O escore de calcio coronariano foi anormal quando acima de oitenta pela escala de Agatston, sendo observado em um percentual baixo (21,7%) dos pacientes, possivelmente porque a tomografia pode nao ser o metodo ideal para detectar aterosclerose em doentes renais, por nao distinguir calcificacoes intimais da camada media. O controle clinico adequado, a baixa faixa etaria e fatores relacionados ao tempo de dialise pre-transplante ou ao efeito antiinflamatorio das drogas pos-transplante podem retardar o aparecimento das calcificacoes. CONCLUSAO: A avaliacao da carga aterosclerotica atraves do duplex scan das carotidas (33,3%) e do escore de calcio coronariano (20%) nao foi frequente, nao havendo correlacao com o elevado indice de deteccao de disfuncao endotelial observado com o exame da reatividade braquial (86,7%).