Bases biológicas del cáncer: una propuesta de contenidos mínimos para las carreras de la salud / Biological bases of cancer: a proposal of minimum contents for health schools

El cáncer constituye la segunda de causa de muerte a nivel mundial y se estima será la primera, superando a las cardiovasculares. El estudio de sus bases moleculares ha permitido el desarrollo de la quimioterapia clásica, como de nuevas terapias biológicas. Si bien estos avances han redundado en un aumento en la sobrevida, no ha impactado en una menor incidencia de los casos. Esto último se debe, en parte, al desconocimiento de los múltiples factores carcinogénicos existentes y los efectos de sus interacciones para cada uno de los tumores. En este sentido, es interesante notar que, en los currículos de las escuelas de salud de las universidades chilenas, el cáncer u oncología como tal, no constituye una cátedra en sí misma, siendo sus contenidos tangencialmente abordados en distintos momentos de la formación; en biología celular, medicina interna y cirugía, entre otros. Con estos antecedentes, el propósito de este trabajo es ofrecer un propuesta sencilla y accesible para los estudiantes, respecto de los contenidos que, a nuestro juicio, son esenciales para comprender las bases biológicas de esta enfermedad y enfrentar con mejores conocimientos el ciclo clínico posterior. A continuación, el lector se encontrará con principios fundamentales de la biología humana normal (como el ciclo celular y el dogma central de la biología molecular), que permiten obtener una visión global de los mecanismos fisiológicos cuya desregulación conlleva a una neoplasia maligna. Luego se entregarán algunas definiciones amplias en relación con los conceptos de neoplasia, tumor benigno y maligno. Para, finalmente, abordar las principales etapas que permiten el desarrollo del cáncer; (i) iniciación, (ii) promoción y (iii) progresión. En esta última, se profundizará por separado, en angiogénesis, degradación de la matriz extracelular, migración y evasión de la respuesta inmune. Este trabajo no aborda materias relacionadas con la hipótesis metabólica del cáncer.

Cancer constitutes the second most common cause of death worldwide and is expected to become the leading one, even above cardiovascular diseases. The understanding of the cellular and molecular basis of cancer has led not only to the proper development of chemotherapy but also of target therapies. Although these advances are related with improved survival rates among cancer patients, it has poorly impacted its incidences. In this regard, the lack of knowledge regarding the impact that the several carcinogenic factors and their interactions have on different types of cancers may explain at least in part the difficulties to reduce incidence rates. However, is worth noticing that in several health schools of chilean universities, cancer does not constitute a formal course, being only partially approached during other courses, such as cell biology, internal medicine, and surgery. Thus, the aim of our work is to provide students a simple and resumed manuscript about essential topics necessary to understand the biological basis of cancer. First, the reader will find some fundamentals about human biology including the cell cycle and the central dogma of molecular biology, which offers an overview of the physiological mechanisms leading to malignant neoplasia. Then, we will provide current definitions of neoplasia, benign and malignant tumors are provided. Finally, the different stages of tumor progression will be approached to allow the understanding of cancer development. These stages include (i) initiation, (ii) promotion, and (iii) progression. For the last one, metastasis, angiogenesis, extracellular matrix degradation, migration, and immune evasion will also be addressed. This work will not consider the metabolic hypothesis of cancer.

Proposal of a clinical score to stratify the risk of multidrug-resistant gram-negative rods bacteremia in cancer patients

ABSTRACT Introduction: Multidrug-resistant gram-negative rods (MDR GNR) represent a growing threat for patients with cancer. Our objective was to determine the characteristics of and risk factors for MDR GNR bacteremia in patients with cancer and to develop a clinical score to predict MDR GNR bacteremia. Material and Methods: Multicenter prospective study analyzing initial episodes of MDR GNR bacteremia. Risk factors were evaluated using a multiple logistic regression (forward-stepwise selection) analysis including variables with a p < 0.10 in univariate analysis. Results: 394 episodes of GNR bacteremia were included, with 168 (42.6 %) being MDR GNR. Five variables were identified as independent risk factors: recent antibiotic use (OR = 2.8, 95 % CI 1.7-4.6, p = 0.001), recent intensive care unit admission (OR = 2.9, 95 % CI 1.1-7.8, p = 0.027), hospitalization ≥ 7 days prior to the episode of bacteremia (OR = 3.5, 95 % CI 2-6.2, p = 0.005), severe mucositis (OR = 5.3, 95 % CI 1.8-15.6, p = 0.002), and recent or previous colonization/infection with MDR GNR (OR = 2.3, 95 % CI 1.2-4.3, p = 0.028). Using a cut-off value of two points, the score had a sensitivity of 66.07 % (95 % CI 58.4-73.2 %), a specificity of 77.8 % (95 % CI 71.4-82.7 %), a positive predictive value of 68 % (95 % CI 61.9-73.4 %), and a negative predictive value of 75.9 % (95 % CI 71.6-79.7 %). The overall performance of the score was satisfactory (AUROC 0.78; 95 % CI 0.73-0.82). In the cases with one or none of the risk factors identified, the negative likelihood ratio was 0.18 and the post-test probability of having MDR GNR was 11.68 %. Conclusions: With the growing incidence of MDR GNR as etiologic agents of bacteremia in cancer patients, the development of this score could be a potential tool for clinicians.

Microbiology and clinical characteristics of viridans group streptococci in patients with cancer

ABSTRACT This study assessed the microbiology, clinical syndromes, and outcomes of oncologic patients with viridans group streptococci isolated from blood cultures between January 1st, 2013 and December 31st, 2016 in a referral hospital in Mexico using the Bruker MALDI Biotyper. Antimicrobial sensitivity was determined using BD Phoenix 100 according to CLSI M100 standards. Clinical information was obtained from medical records and descriptive analysis was performed.Forty-three patients were included, 22 females and 21 males, aged 42 ± 17 years. Twenty (46.5%) patients had hematological cancer and 23 (53.5%) a solid malignancy. The viridans group streptococci isolated were Streptococcus mitis, 20 (46.5%); Streptococcus anginosus, 14 (32.6%); Streptococcus sanguinis, 7 (16.3%); and Streptococcus salivarius, 2 (4.7%). The main risk factors were pyrimidine antagonist chemotherapy in 22 (51.2%) and neutropenia in 19 (44.2%) cases, respectively. Central line associated bloodstream infection was diagnosed in 18 (41.9%) cases. Septic shock occurred in 20.9% of patients, with an overall mortality of 18.6%. Only four S. mitis revealed penicillin-resistance.Our results are similar to those of other series, identifying these bacteria as emerging pathogens with significant morbidity and mortality in oncologic patients. The MALDI-TOF system increased the rate of viridans group streptococci isolation in this population.

Microorganismos aislados de hemocultivos en niños con cáncer y neutropenia febril de alto riesgo en cinco hospitales de Santiago, Chile, período 2012-2015 / Microorganisms isolated from blood cultures in children with cancer and high-risk febrile neutropenia from five hospitals in Santiago, Chile, 2012-2015

Resumen Antecedentes: Los microorganismos aislados de hemocultivos (HC) en pacientes con neutropenia febril (NF) varían en el tiempo, siendo necesaria su vigilancia para orientar una terapia empírica adecuada. Objetivo: Identificar microorganismos aislados de HC y su perfil de resistencia (R) a antimicrobianos en niños con cáncer y NF de alto riesgo. Método: Estudio prospectivo, multicéntrico de episodios de NF de alto riesgo en pacientes bajo 18 años de edad, de cinco hospitales en Santiago de Chile, 2012-2015. Análisis de HC positivos. Resultados: Se analizaron 206 microorganismos en 185 episodios de NF de alto riesgo con HC positivos. Los aislados principales fueron bacilos gramnegativos (BGN) (46,6%) y cocáceas grampositivas (CGP) (45,1%) y los microorganismos más frecuentes Escherichia coli (22,8%), Staphylococcus coagulasa negativa (18,0%) y Klebsiella spp (16,5%). En resistencia (R) a antimicrobianos destaca: E. coli y Klebsiella spp 4,2 y 67,6% R a cefalosporinas de tercera generación (cefotaxima/ceftriaxona) respectivamente, 10,6 y 40,6% R a ciprofloxacina y 2,1 y 26,5% a amikacina, respectivamente. S. coagulasa negativa y S. aureus 86,4% y 22,2% R a oxacilina, Streptococcus grupo viridans 71% R a penicilina. Discusión: Este estudio actualiza la etiología y el perfil de R de microorganismos aislados en HC de niños con cáncer y NF de alto riesgo, herramienta esencial para el adecuado manejo de estos pacientes.

Background: Microorganisms isolated from blood cultures (BC) in patients with febrile neutropenia (NF) vary over time, requiring systematic monitoring to guide appropriate empirical therapy. Aim: To identify microorganisms isolated from BC and their antimicrobial resistance profile in children with cancer and high risk NF. Method: Prospective, multicenter study. The analysis included episodes of high-risk FN with positive BC in children under 18 years of age treated in five hospitals in Santiago, Chile, 2012-2015. Results: A total of 206 microorganisms were analyzed in 185 episodes of high-risk FN. The main isolates were Gram negative bacilli (46.6%) and Gram positive cocci (45.1%) and the most frequent microorganisms were Escherichia coli (22.8%), coagulase negative Staphylococcus (18.0%) and Klebsiella spp. (16.5%). Escherichia coli and Klebsiella spp showed 4.2% and 67.6% resistance to third generation cephalosporins (cefotaxime/ceftriaxone), 10.6% and 40.6% resistance to fluoroquinolones (ciprofloxacin) and 2.1% and 26.5% to amikacin, respectively. Coagulase negative Staphylococcus and Staphylococcus aureus had 86.4% and 22.2% resistance to oxacillin, Streptococcus viridans group had 71% resistance to penicillin. Discussion: This study updates the etiology and resistance profile of microorganisms isolated in BC from children with cancer and high risk FN, an essential tool for the adequate management of these patients.

Análisis de concentraciones plasmáticas de voriconazol y su perfil de seguridad en pacientes oncológicos pediátricos / Analysis of voriconazole serum concentrations and safety profile in pediatric oncology patients

Background: Voriconazole (VCZ) serum drug levels (SDL) vary widely and are associated with increased mortality when they are below the therapeutic range for invasive aspergillosis (IA). Aim: To describe VCZ SDL in oncology pediatric patients in order to reach adequate concentrations for prophylaxis (≥ 0.5 mg/L) and treatment (≥ 1.0 y 2.0 mg/L) for IA and their relationship with toxicity. Patients and Methods: Retrospective analysis of VCZ SDL and toxicities recorded in oncology pediatric patients between February 2013 and November 2014. The daily dosage and SDLs were analyzed according to administration route: intravenous (IV) and oral (PO), type of therapy (prophylaxis and treatment) and patient age (< 12 y ≥ 12 years old). Results: 112 through levels from 26 patients were analyzed and the average age was 9.3 years-old. The SDL obtained from the IV route were 43.7%. There were more SDL ≥ 0.5 mg/L and ≥ 1.0 mg/L with the IV route than the PO route (p < 0.05). Patients younger than 12-years-old received a higher dosage than those ≥ 12 years old (median 18.6 and 9.2 mg/kg/d, respectively, p < 0.05). To reach SDL ≥ 0,5 mg/L with the PO route, a dosage of 200 mg every 12 hours showed the best results for all patients (80-100% SDL ≥ 0.5 mg/L). With an IV dosage between 14 and 20 mg/kg/day in patients > 12-years-old, 80% of the SDL were ≥ 1 mg/L and ≥ 2 mg/L. In patients younger than 12-year-old, dosages between 8-30 mg/ kg/day showed similar results (50-63% of SDL ≥ 1 mg/L and 36-40% of SDL ≥ 2 mg/L). Eight patients (30.8%) presented an adverse drug reaction and no relationship with the SDL was found. Conclusión: A VCZ standard dosage of 200 mg every 12 hours PO showed the best results for IA prophylaxis in all patients. Patients younger than 12-years-old would require higher dosages than the doses used in this study to attain adequate SDL for IA treatment. No relation with SDL and adverse reactions was found.

Introducción: Las concentraciones plasmáticas (CPs) de voriconazol (VCZ) son erráticas y en el caso de encontrarse bajo rango terapéutico para el tratamiento de aspergilosis invasora (AI) se asocian a un aumento de mortalidad. Objetivo: Analizar las CPs de VCZ obtenidas en pacientes pediátricos para alcanzar valores que se estiman efectivos para profilaxis (≥ 0,5 mg/L) y tratamiento (≥ 1,0 y 2,0 mg/L) de AI y su relación con toxicidades. Pacientes y Métodos: Análisis retrospectivo de CPs de VCZ y toxicidades asociadas obtenidas en pacientes oncológicos pediátricos desde febrero de 2013 hasta noviembre 2014. Se analizó la dosis diaria y CPs de acuerdo a la vía de administración: intravenosa (iv) u oral (vo), tipo de terapia (profilaxis y tratamiento) y edad (< 12 y ≥ 12 años). Resultados: Se analizaron 112 CPs valle de 26 pacientes, con una edad promedio de 9,3 años. El 43,7% de las CPs correspondió a administración iv. Se obtuvieron más CPs ≥ 0,5 mg/L y ≥ 1,0 mg/L con la vía iv en relación a vo (p < 0,05). Pacientes bajo 12 años de edad recibieron mayor dosis en comparación a los ≥ 12 años (medianas 18,6 y 9,2 mg/kg/día, respectivamente, p < 0,05). La dosis vo más efectiva para alcanzar CPs ≥ 0,5 mg/L fue de 200 mg cada 12 h en todos los pacientes (80-100% de CPs ≥ 0,5 mg/L). En pacientes ≥ 12 años con dosis iv entre 14 y 20 mg/kg/día, 80% de las CPs fueron ≥ 1 mg/L y ≥ 2 mg/L. En pacientes bajo 12 años de edad, dosis entre 8-30 mg/ kg/día generaron similares resultados (50-63% para CPs ≥ 1 mg/L y 36-40% para CPs ≥ 2 mg/L). Ocho pacientes (30,8%), tuvieron alguna reacción adversa al fármaco, no encontrándose relación con la CP alcanzada. Conclusión: Una dosis estándar vo de 200 mg c/12 h de VCZ mostró los mejores resultados para profilaxis de AI en todos los pacientes. Pacientes bajo 12 años de edad requerirían dosis mayores a las utilizadas en este estudio para obtener CPs efectivas para tratamiento de AI. No se encontró relación entre CPs tóxicas y reacciones adversas.

Predictors of 7- and 30-day mortality in pediatric intensive care unit patients with cancer and hematologic malignancy infected with Gram-negative bacteria

Background: Infection with Gram-negative bacteria is associated with increased morbidity and mortality. The aim of this study was to evaluate the predictors of 7- and 30-day mortality in pediatric patients in an intensive care unit with cancer and/or hematologic diseases and Gram-negative bacteria infection. Methods: Data were collected relating to all episodes of Gram-negative bacteria infection that occurred in a pediatric intensive care unit between January 2009 and December 2012, and these cases were divided into two groups: those who were deceased seven and 30 days after the date of a positive culture and those who survived the same time frames. Variables of interest included age, gender, presence of solid tumor or hematologic disease, cancer status, central venous catheter use, previous Pseudomonas aeruginosa infection, infection by multidrug resistant-Gram-negative bacteria, colonization by multidrug resistant-Gram- negative bacteria, neutropenia in the preceding seven days, neutropenia duration ≥3 days, healthcare-associated infection, length of stay before intensive care unit admission, length of intensive care unit stay >3 days, appropriate empirical antimicrobial treatment, definitive inadequate antimicrobial treatment, time to initiate adequate antibiotic therapy, appropriate antibiotic duration ≤3 days, and shock. In addition, use of antimicrobial agents, corticosteroids, chemotherapy, or radiation therapy in the previous 30 days was noted. Results: Multivariate logistic regression analysis resulted in significant relationship between shock and both 7-day mortality (odds ratio 12.397; 95% confidence interval 1.291–119.016 p = 0.029) and 30-day mortality (odds ratio 6.174; 95% confidence interval 1.760–21.664 p = 0.004), between antibiotic duration ≤3 days and 7-day mortality (odds ratio 21.328 95% confidence interval 2.834-160.536; p = 0.003), and between colonization by multidrug re...

Colonization with Clostridium difficile in children with cancer

Clostridium difficile is a gram-positive, anaerobic, spore-forming bacillus. Usually it does not cause disease unless a patient who is colonized with toxin-producing strains has been treated with antibiotics, particularly those that change the anaerobic flora of the large intestine. We investigated in a prospective study intestinal colonization of C. difficile and its toxins in children with malignancy that used different antibiotics and cytotoxic drugs. One hundred fifty-two patients were included in this prospective study. Stool samples were obtained within the first 48 hours after admission and cultured for C. difficile; cytopathic effect of C. difficile was detected on HELA cells, also ELISA test was performed for detection of toxins A and B. 25% of patients had positive culture for C. difficile; 36/38 [92%] revealed positive cytopathic effect on HELA cells. No significant relation was found between age, gender, history of antibiotic consumption and C. difficile positive culture and cytopathic effect on HELA cells. The only relation was seen between cotrimoxazol and cytopathic effect on HELA cells [P=0.03]. Although the rate of C. difficile colonization [25.6%] and toxigenic strains [23.7%] in admitted children in hematologic ward is high, the rate of ELISA positive test for toxin A+B was not correspond with culture and HELA cell. With respect to sensitivity and specificity of ELISA test, possibility for existence of toxin C with cytopathic effect is high in this type of patients

Predictors and clinical outcomes of persistent methicillin-resistant Staphylococcus aureus bacteremia: a prospective observational study

BACKGROUND/AIMS: The high mortality attributable to persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in spite of glycopeptide treatment has heightened the need for early detection and intervention with alternative agents. The purpose of this study was to determine the clinical characteristics of and risk factors for persistent MRSA bacteremia. METHODS: All first episodes of significant MRSA bacteremia at a 710-bed academic medical center from November 2009 through August 2010 were recorded. Blood cultures were conducted at 3 days and every 2 to 3 days thereafter until clearance. Clinical characteristics and outcomes were compared between persistent MRSA bacteremia (> or = 7 days) and nonpersistent MRSA bacteremia (< or = 3 days). RESULTS: Of 79 patients with MRSA bacteremia during the study period, 31 (39.2%) had persistent MRSA bacteremia. The persistent MRSA bacteremia group had significantly higher 30-day mortality than the nonpersistent MRSA bacteremia group (58.1% vs. 16.7%, p < 0.001). Multivariate analysis indicated that metastatic infection at presentation (odds ratio [OR], 14.57; 95% confidence interval [CI], 3.52 to 60.34; p < 0.001) and delayed catheter removal in catheter-related infection (OR, 3.80; 95% CI, 1.04 to 13.88; p = 0.004) were independent predictors of persistent MRSA bacteremia. Patients with a time to blood culture positivity (TTP) of < 11.8 hours were at increased risk of persistent MRSA bacteremia (29.0% vs. 8.3%, p = 0.029). CONCLUSIONS: High mortality in patients with persistent MRSA bacteremia was noted. Early detection of metastatic infection and early removal of infected intravascular catheters should be considered to reduce the risk of persistent MRSA bacteremia. Further studies are needed to evaluate the role of TTP for predicting persistent MRSA bacteremia.

Agentes causantes de bacteriemia en niños con cáncer y neutropenia febril de alto riesgo en seis hospitales de Santiago, Chile, período 2004-2009 / Bloodstream infections in children with cancer and high risk fever and neutropenia episodes in six hospitals of Santiago, Chile between 2004 and 2009

Introduction: To determine the etiology of invasive bacterial infection in high risk febrile neutropenia (HRFN) episodes in children with cancer is essential because of the favorable impact on mortality of the early empiric antibiotic treatment. Objective: To determine the etiology of bacteremia in pediatric patients with cancer and HRFN in the National Child Program of Antineoplastic Drugs during the 2004-2009 period, and compare these agents and their antimicrobial susceptibility with the period 1994-1998 described in a previous study. Methods: The causative agents of bacteremia were prospectively recorded in patients less than 18 years of age receiving chemotherapy for cancer with HRFN and positive blood cultures admitted to one of the six hospitals from the Child Program of Antineoplastic Drugs network during the period 2004-2009. Results: 839 episodes of HRFN were identified; 181 blood cultures were positive in the following proportion: gram positive cocci (56%), gram negative bacilli (42%) and yeast (2%).The most common etiologic agents were Staphylococcus coagulase negative (25%), Escherichia. coli (20%), group viridans Streptococcus (14%), Staphylococcus aureus (13%) and Pseudomonas aeruginosa (9%). Comparing the two periods, the relative frequency of Streptococcus spp increased from 4 to 17%, coagulase negative Staphylococcus decreased from 44 to 25%, showing an increase in their resistance to oxacillin from 55% to 77%. Conclusions: We describe the main etiological agents from HRFN episodes in children with cancer in a 5 years period. This information could help for a better approach in the empirical antimicrobial therapy in this population.

Introducción: Conocer la etiología de los episodios de neutropenia febril de alto riesgo (NFAR) en pacientes con cáncer tiene importancia para implementar tratamientos antimicrobianos ajustados a la epidemiología local, lo que tiene impacto en la morbilidad y mortalidad. Objetivo: Describir la etiología de las bacteriemias en niños con cáncer y NFAR en el período 2004-2009, en la red PINDA de Santiago (Región Metropolitana), Chile, y comparar estos agentes y su susceptibilidad antimicrobiana con un estudio previo realizado en el período 1994-1998. Material y Métodos: Se registraron prospectivamente los agentes causantes de bacteriemia y su susceptibilidad a antimicrobianos de los pacientes bajo 18 años de edad en tratamiento quimioterápico por cáncer, ingresados con diagnóstico de NFAR a los seis hospitales de la red, durante el período 2004-2009. Resultados: De 839 episodios de NFAR, 181 tuvieron hemocultivos positivos, correspondientes a cocáceas grampositivas (56%), bacilos gramnegativos (42%) y levaduras (2%). Los agentes más frecuentemente aislados fueron: Staphylococcus coagula-sa negativa (25%), Escherichia coli (20%), Streptococcus grupo viridans (14%), Staphylococcus aureus (13%) y Pseudomonas spp (9%). Al comparar los dos períodos de tiempo, destacan los siguientes cambios significativos: disminución en frecuencia relativa de Staphylococcus coagulasa negativa (desde 44 a 25%), aumento de Streptococcus spp (desde 4 a 17%), y aumento de la resistencia de Staphylococcus coagulasa negativa a oxacilina (desde 55 a 77%). Conclusiones: Se dan a conocer los principales agentes etiológicos de los episodios de NFAR y la susceptibilidad a antimicrobianos en un período de cinco años. Esto permite racionalizar el manejo antimicrobiano empírico de los episodios de NFAR en esta población.

Bacteriemia en pacientes oncológicos: Experiencia en un hospital pediátrico / Bacteremia in cancer patients: Experience in a pediatric hospital

The use of intensive chemotherapy has improved survival of children with cancer. However, this is associated to severe and maintained neutropenia, increasing risks of severe infections like bacteremia. Aim: To update information on microorganisms involved in bloodstream infections in cancer patients and their antimicrobial resistance patterns during the last 3 years in our hospital, comparing it with our previous experience and with other Chilean centres. Material and Methods: Analysis of positive blood cultures belonging to cancer patients during 2006-2008 registered in the Microbiology Lab at the Roberto Del Rio Children's Hospital. Results: In 52 patients, 96 blood cultures yielded bacteria: 59.4% gram positive cocci and 34.4%, gram negative rods. Coagulase negative Staphylococci (CNS) were the most frequent bacteria isolated and enterobacteria were in the second place. Susceptibility to cloxacillin was 11% in CNS and 70 % in Staphylococcus aureus isolates. Enterobacteria maintained susceptibility to third generation cephalosporins and aminoglycosides. Conclusion: Despite the low sensitivity of CNS to cloxacillin, the empirical antibiotic treatment in our unit must include cloxacillin because of the high susceptibility of S. aureus. Switching to vancomycin should be considered only if SCN is isolated or there is an unfavorable evolution.

El uso de quimioterapia más intensiva ha mejorado la sobrevida de los niños con cáncer. Sin embargo, esto se asocia a neutropenia intensa y mantenida, aumentando el riesgo de infecciones graves como bacteriemias. Objetivo: Actualizar la información sobre los microorganismos implicados en las infecciones del torrente circulatorio en pacientes oncológicos atendidos en nuestro hospital, comparar con la literatura médica y describir el patrón de resistencia antimicrobiana. Material y Métodos: Se revisaron los registros de hemocultivos del Laboratorio de Microbiología del Hospital de Niños Roberto Del Río entre los años 2006 y 2008, seleccionando aquellos con resultado positivo y que pertenecieran a pacientes con cáncer. Resultados: En 52 pacientes, 96 hemocultivos resultaron positivos: cocáceas grampositivas 59,4% (Staphylococcus coagulasa negativa-SCN fue el más frecuente); bacilos gramnegativos 34,4%, predominando las enterobacterias, en segundo lugar. Se observó en SCN una susceptibilidad a cloxacilina de 11% y en Staphylo-coccus aureus de 70%. Las enterobacterias mantuvieron una susceptibilidad estable para cefalosporinas de tercera generación y aminoglucósidos. Conclusión: A pesar de la baja susceptibilidad de SCN a cloxacilina, el tratamiento antimicrobiano empírico de primera línea en nuestra unidad debe incluir cloxacilina dada la alta susceptibilidad de S. aureus, y el cambio a vancomicina debería plantearse frente al aislamiento de SCN o evolución desfavorable.

The effect of age on the bacteria isolated and the antibiotic-sensitivity pattern in infections among cancer patients.

Background: Patients with cancer are predisposed to infections. Antimicrobial patterns and antibiotic sensitivity change with increasing age, making choice of empirical therapy more complicated. Materials and Methods: This single-center study aims to try and assess the influence of age on microbiology and antibiotic sensitivity of organisms causing infection in patients with malignant disease. Results : The five most common bacterial pathogens isolated were Pseudomonas sp (245, 26.2%) > Enterocococcus sp (109, 11.66%) > Staphylococcus aureus (107, 11.44%) > Escherichia coli (106, 11.34%) > Klebsiella sp (99, 10.59%). There was no significant change in the distribution of Gram-positive and Gram-negative bacteria with age. However, there was an increase in the occurrence of the Enterobacteriacea group and a decrease in infections caused by nonlactose fermenters with increasing age. The ESBL production increased from 10.52% (12-19 years) to 24.88% (>50 years) as did oxacillin resistance (from 14.3% to 28.1%) among S. aureus isolates. The activity of most antimicrobial agents decreased with increasing age. The decreasing trend of activity was statistically significant for meropenam (73.3-41.2%) against Pseudomonas sp. and for the activity of the aminoglycosides for Acinetobacter sp (61.1-17.4% for amikacin). Conclusions : This suggests that empirical antibiotic therapy needs to be changed on the basis of the age of the patient. It also appears that combination therapy is essential for the empirical treatment of infections in elderly patients with cancer.

Caracterização molecular de Pseudomonas aeruginosa resistentes a carbapenêmicos e produtoras de metalo-β-lactamase isoladas em hemoculturas de crianças e adolescentes com câncer / Molecular characterization of carbapenem-resistant and metallo-β-lactamase-producing Pseudomonas aeruginosa isolated from blood cultures from children and teenagers with cancer

INTRODUCÃO: O objetivo do estudo foi avaliar a prevalência e a disseminação de amostras de Pseudomonas aeruginosa resistente aos carbapenêmicos e produtoras de metalo-β-lactamases isoladas de hemoculturas (2000-2005) de pacientes do Instituto de Oncologia Pediátrica da UNIFESP (IOP-GRAACC). MÉTODOS E RESULTADOS: Cinquenta e seis amostras de Pseudomonas aeruginosa foram isoladas de 49 pacientes. Trinta e duas dessas amostras foram classificadas como resistentes aos carbapenêmicos pela técnica de disco difusão e submetidas a reação de PCR para detecção de genes de MBL. Dezoitos dessas 32 amostras evidenciaram o gene blaSPM-1. Oito amostras selecionadas em diferentes anos no período de estudo apresentaram o mesmo perfil genético por pulsed-field gel electrophoresis. A terapêutica antimicrobiana foi considerada adequada em apenas 23,5 por cento dos pacientes com bacteremia por P. aeruginosa carreando blaSPM-1 e letalidade de 70,6 por cento no período de até 30 dias após a bacteremia e uma inadequação inicial dos esquemas antibióticos utilizados CONCLUSÕES: Evidenciamos a presença de um clone de P. aeruginosa resistente aos carbapenêmicos carreando blaSPM-1 que persistiu em amostras de hemocultura pelo período de 6 anos na instituição, com alta letalidade, justificando uma vigilância epidemiológica rigorosa e uma readequação dos esquemas de terapia antimicrobianos na instituição.

INTRODUCTION: The objective of this study was to evaluate the prevalence and dissemination of carbapenem-resistant and metallo-β-lactamase-producing Pseudomonas aeruginosa isolated from blood-stream samples (2000-2005) that were collected from patients admitted to the Institute of Pediatric Oncology, UNIFESP (IOP-GRAACC). METHODS AND RESULTS: Fifty-six P. aeruginosa samples were isolated from 49 patients. Thirty-two of these samples were classified as carbapenem-resistant using the disc diffusion method and were subjected to the PCR reaction in order to detect MBL genes. Eighteen of these 32 isolates showed the blaSPM-1 gene. Eight samples selected in different years over the study period presented the same genetic profile according to pulsed-field gel electrophoresis. The antimicrobial therapy was considered adequate for only 23.5 percent of the patients with bacteremia due to P. aeruginosa carrying the blaSPM-1 gene, and a high lethality rate of 70.6 percent was observed during the 30-day period after bacteremia and an inadequate initial antibiotic regimen. CONCLUSIONS: We detected the presence of a clone of carbapenem-resistant P. aeruginosa carrying blaSPM-1 that persisted in blood culture samples over a six-year period at the institution, with high lethality, thus justifying rigorous epidemiological surveillance and a rearrangement of the antimicrobial therapy regimens at the institution.

Blood stream infections in cancer patients: A single center experience of isolates and sensitivity pattern.

Background : Up to 10% of patients who develop a nosocomial blood stream infection (BSI) in the hospital have an underlying malignancy. The treatment of infections in patients with malignancy often relies on the use of established guidelines along with the consideration of the local microbiology and antibiotic sensitivity patterns of possible etiologic agents. AIMS: This study attempts to identify the likely etiologic agents and the antibiotic sensitivity profile of BSIs in cancer patients. Settings and Design: This was a retrospective study. Methods and Material: The study was conducted at a tertiary care center for cancer patients, in which samples representing blood stream infections sent from the Medical Oncology services of the hospital during the year of 2007 were analysed. The microbiological profile and antibiotic sensitivity pattern of these isolates was studied. Results: There were 484 isolates that represented BSIs. The most common bacterial isolates from patients with cancer were Pseudomonas spp. (30.37%), Staphylococcus aureus (12.6%) and Acinetobacter spp. (11.57%). Meropenem was the most effective antibiotic with 71.2% sensitivity to the bacterial isolates it was tested against. Oxacillin resistance was seen in 18% of S. aureus isolates. Conclusion: Gram-negative bacteria were more common as etiologic agents of BSIs in cancer patients. The poor activity of the primary empirical agents for infections in cancer namely ceftazidime and piperacillin-tazobactam is alarming.Strict regulation of vancomycin use should be considered in areas where there is a low prevalence of methicillin-resistant S. aureus (MRSA).

Microbiological and host features associated with corynebacteriosis in cancer patients: a five-year study

During a five-year period, 932 clinical isolates from cancer patients treated in a Brazilian reference centre were identified as corynebacteria; 86 percent of the cultures came from patients who had been clinically and microbiologically classified as infected and 77.1 percent of these patients had been hospitalised (71.1 percent from surgical wards). The adult solid tumour was the most common underlying malignant disease (66.7 percent). The univariate and multivariate analyses showed that hospitalised patients had a six-fold greater risk (OR = 5.5, 95 percent CI = 1.15-26.30 p = 0.033) related to 30-day mortality. The predominant species were Corynebacterium amycolatum (44.7 percent), Corynebacterium minutissimum (18.3 percent) and Corynebacterium pseudodiphtheriticum (8.5 percent). The upper urinary tracts, surgical wounds, lower respiratory tracts, ulcerated tumours and indwelling venous catheters were the most frequent sources of C. amycolatum strains. Corynebacterium jeikeium infection occurred primarily in neutropenic patients who have used venous catheters, while infection caused by C. amycolatum and other species emerged mainly in patients with solid tumours.

Etiología de episodios de neutropenia febril en pacientes adultos con cáncer hematológico y de órganos sólidos en el Hospital Clínico Universidad Católica, Santiago-Chile / Etiology of febrile neutropenia episodes among cancer patients from Hospital Clinico Universidad Catolica, Santiago-Chile

Introduction: The surveillance of febrile neutropenia (FN) episodes in every center allows adapt the antibiotic therapy guidelines to local epidemiology. Aim: To characterize clinical features and compare the FN etiology between hematological cáncer (HC) and solid organ cancer (SOC) in our center. Patients and Methods: Surveillance study in adult patients with FN admitted to Hospital Clinico Universidad Católica, in Santiago, Chile, from January 2004 to August 2007. Results: 154 FN episodes corresponding to 87 patients were included. Mean age: 47 ± 6 years-old; 71 percent had HC and 29 percent SOC. A clinical and/or microbiologically documented infection was recognized in 76 percent. Gastrointestinal 31.5 percent, upper respiratory 30.3 percent and lower respiratory 16.9 percent were the more frequent clinical focus. In 30.5 percent blood culture resulted positive: gram negative rods 51 percent, gram positive cocci 41 percent and yeasts 8 percent; being Escherichia coli 22 percent, S. coagulase negative (SCoN) 20 percent and Klebsiella pneumoniae 12 percent most frequent bacteria; 22.2 percent Enterobacteriaceae were ESBL producers and 55.6 percent 5CoN were methicillin resistant. In 18.3 percent of FN episodes the etiology was not established. Highest mortality was observed in episodes with microbiologically documented infection (14.5 percent vs 1.3 percent, p < 0.005). A clinical observed focus and positive blood cultures were more frequently obtamed among HC than SOC associated episodes: 37.3 percent vs 13.6 percent; (p < 0.01) and 67.2 percent vs 50 percent; (p = 0.045), respectively. Conclusions: The etiological profile of FN in our center and the necessity to continue the surveillance was described. Future studies are needed regarding risk factors of invasive infection that have worst prognosis.

Introducción: La vigilancia de la etiología de los episodios de neutropenia febril (NF) en cada centro permite adaptar guías de antibioterapia a la epidemiología local. Objetivo: Caracterizar y comparar la etiología de la NF en pacientes con cáncer hematológico (CH) y de órganos sólidos (COS). Pacientes y Métodos: Estudio de vigilancia de NF de pacientes adultos en el Hospital Clínico Universidad Católica, en Santiago, Chile, entre enero 2004 y agosto 2007. Resultados: 154 episodios de NF correspondientes a 87 pacientes: 47 ± 6 años; 71 por ciento CH y 29 por ciento COS. Se documentó infección clínica y/o microbiológicamente en 76 por cientoo. Más frecuente fueron: foco gastrointestinal 31,5 por ciento, respiratorio alto 30,3 por cientoo y respiratorio bajo 16,9 por cientoo. En 30,5 por cientoo hubo hemocultivos positivos: bacilos gramne-gativos en 51 por ciento, cocáceas grampositivas en 41 por ciento, levaduras en 8 por cientoo; predominando: Escherichia coli 22 por cientoo, Staphylococcus coagulasa negativa (SCoN) 20 por cientoo y Klebsiella pneumoniae 12 por ciento; 22,2 por cientoo de las entero-bacterias eran productoras de (3-lactamasa de espectro expandido y 55,6 por cientoo >SCoN meticilina resistentes. En 18,3 por cientoo de los episodios no se identificó causa de fiebre. Hubo mayor mortalidad en episodios con documentación microbiológica (14,5 por ciento vs 1,3 por ciento, p < 0,005). En los pacientes con CH fue más frecuente obtener hemocultivos positivos (37,3 por cientoo vs 13,6 por ciento; p < 0,01) e identificar foco clínico (67,2 por ciento vs 50 por ciento; p = 0,045). Conclusiones: Se establece el perfil etiológico de las NF en nuestro centro y la necesidad de mantener vigilancia. En futuros estudios será necesario evaluar factores de riesgo de pacientes con infecciones invasores que tendrían peor pronóstico.