Caracterización clínica, epidemiológica y microbiológica de bacteriemias producidas por enterobacterias resistentes a carbapenems en un hospital universitario de Córdoba, Argentina / Clinical, epidemiological and microbiological characterization of bacteremia produced by carbapenem-resistant enterobacteria in a university hospital in Córdoba, Argentina

Resumen Introducción: Las enterobacterias son una causa principal de infecciones del torrente sanguíneo y su resistencia antimicrobiana se encuentra en aumento. Esto lleva a un incremento de la morbilidad-mortalidad y de los costos en la salud pública. Las enterobacterias resistentes a carbapenems representan un grave desafío a nivel global ya que existen escasas opciones terapéuticas disponibles. Objetivo: Caracterización clínico/microbiológica de las bacteriemias resistentes a carbapenémicos observadas en un período de 4 años. Material y Método: Estudio retrospectivo, observacional y descriptivo, sobre las bacteriemias por enterobacterias resistentes y sensibles a carbapenems. Resultados: Se analizó un total de 84 pacientes con bacteriemia por enterobacterias resistentes y sensibles a carbapenems. Entre las resistentes, observamos una mayor proporción de: tratamiento antimicrobiano previo, hospitalización en unidad de terapia intensiva (UTI), inicio de la bacteriemia en UTI y antecedentes de β-lactamasas de espectro extendido. Además, se detectó un amplio predominio de Klebsiella pneumoniae productor de KPC y una mortalidad atribuible de 52,4%. Discusión: El estudio posibilitó profundizar el conocimiento de una enfermedad emergente de elevada mortalidad, en vistas al diseño y aplicación de estrategias de control de infecciones y de esquemas de tratamiento efectivos adaptados a la epidemiologia local.

Abstract Background: Enterobacteriaceae are a major cause of bloodstream infections and their antimicrobial resistance continues to increase. This leads to higher morbidity-mortality rates and public health costs. Carbapenem-resistant Enterobacteriaceae represent a serious challenge globally, since there are few therapeutic options available. Aim: Clinical/microbiological characterization of the carbapenem-resistant bacteremia observed over a period of 4 years. Methods: Retrospective, observational and descriptive study about bacteremia caused by carbapenem-resistant and susceptible Enterobacteriaceae. Results: A total of 84 patients with bacteremia including carbapenem-resistant and susceptible Enterobacteriaceae were analyzed. We found that patients infected with carbapenem-resistant strains presented a higher proportion of: previous antibiotic treatment, hospitalization in intensive care unit (ICU), onset of the bacteremia during hospitalization in ICU and previous infection with extended-spectrum-beta-lactamase producing Enterobacteriaceae. Additionally, we observed a predominance of KPC-producing Klebsiella pneumoniae and an attributable mortality rate of 52.4%. Discussion: This study allowed for a better understanding of an emerging problem with high mortality, which in turn is useful for the design and adoption of infection control strategies and effective treatment regimens adapted to our local epidemiology.

Epidemiología de las infecciones urinarias asociadas a catéter y no asociadas a catéter en un hospital universitario de tercer nivel / Nosocomial urinary tract infection: an analysis beyond urinary catheterization

Resumen Introducción: Las infecciones urinarias asociadas a la atención de la salud (ITU-AAS) representan un importante problema sanitario, siendo poco conocidas sus características cuando no están asociadas a cateterización urinaria u ocurren fuera de unidades de cuidados intensivos (UCI). Objetivos: Determinar las características de los pacientes con ITU-AAS, etiología y susceptibilidad antimicrobiana de las mismas, tanto asociadas a catéter (ITU-C) como no asociadas a catéter (ITU-noC), en UCI y en sala general. Materiales y Métodos: Se realizó un estudio analítico retrospectivo de corte transversal entre 2009 y 2013 en un hospital universitario de tercer nivel. Se identificaron todos los episodios de ITU-AAS, diferenciándolas en ITU-C e ITU-noC. Resultados: Se incluyeron 253 episodios de ITU-AAS, siendo más frecuentes las ITU-C (60,9%) respecto a ITU-noC. Un 37,4% de ITU-noC y 59,7% de ITU-C ocurrieron en UCI. Los microorganismos aislados más frecuentemente fueron Escherichia coli, Klebsiella pneumoniae y Enterococcus sp. El 19% de los bacilos gramnegativos fueron productores de β-lactamasa de espectro extendido, siendo su frecuencia similar en ambos grupos. Conclusión: Las co-morbilidades de los pacientes con ITU-AAS, los agentes etiológicos responsables y sus correspondientes espectros de sensibilidad, fueron similares en los grupos de ITU-C e ITU-noC, tanto en sala general como en UCI.

Introduction: Nosocomially acquired urinary tract infections (NAUTI) represent an important public health issue, but its characteristics when they are not catheter associated (CA-UTI) or when they take place outside intensive care units (ICU) are poorly understood. Objectives: To determine the patients' characteristics, etiology and antimicrobial susceptibility of NAUTI, both CA-UTI and no CA-UTI, in general ward and ICU. Methods: We conducted a retrospective analytic cross-sectional study, between 2009 and 2013, in a third level universitary hospital. All NAUTI episodes were identified, classifying them as CA-UTI and no CA-UTI. Results: We included 253 episodes of NAUTI, being CA-UTI (60,9%) more frequent than no CA-UTI. A 37,4% of no CA-UTI and 59,7% of CA-UTI were identified in ICU. The most frequently isolated microorganisms were Escherichia coli, Klebsiella pneumoniae and Enterococcus sp. A 19% of extended spectrum betalactamase producing gram negative bacilli were found, without differences between groups. Conclusion: Patients's comorbidities, microorganisms associated to NAUTI and its antimicrobial susceptibility were similar in CA-UTI and no CA-UTI, as in general ward and ICU.

[Uncomplicated urinary tract infection in women: etiology and antimicrobial resistance]. / Infección urinaria no complicada en mujeres: etiología y resistencia a antimicrobianos.

Our objectives were to determine the etiology and analyze the antibiotic resistance profiles of microorganisms causing uncomplicated urinary tract infections in our setting. An analytical cross-sectional study was conducted. In vitro antimicrobial resistance of urine cultures was analyzed. 580 urine cultures of women over age fifteen were included. 82.6 % of urine cultures corresponded to cystitis and the remaining 17.4 % corresponded to pyelonephritis. 353 urine cultures of women <50 years old (60.9%) and 227 of women = 50 years old (39.1%) were obtained. The most common pathogens were Escherichia coli (85.5 %) and Klebsiella pneumoniae (4.7 %). For Escherichia coli, there was a resistance of 28.6% to trimethoprim-sulfamethoxazole,7.9% to ciprofloxacin and 0.4% to nitrofurantoin. Significant difference (p = 0.005) was seen in the resistance to ciprofloxacin in women = 50 years old. Our data show there is a low in vitro resistance to nitrofurantoin

Nuestros objetivos fueron determinar la etiología y analizar los perfiles de resistencia antimicrobiana de los microorganismos causantes de infecciones urinarias no complicadas en nuestro medio. Se realizó un estudio analítico de corte transversal. Se analizó la resistencia antimicrobiana in vitro de los urocultivos. Se incluyeron 580 urocultivos de mujeres mayores de 15 años. Un 82.6% de urocultivos correspondieron a cistitis y el 17.4% a pielonefritis.Se obtuvieron 353 urocultivos de mujeres < 50 años (60.9%) y 227 a ? 50 años (39.1%).Los patógenos más frecuentes fueron: Escherichia coli (85.5%) y Klebsiella pneumoniae (4.7%). Se encontró una resistencia de E coli a trimetoprima-sulfametoxazol del 28.6%, a ciprofloxacina de 7.9% y a nitrofurantoína de 0.4%. Se evidenció diferencia significativa (p=0.005) en la resistencia de E coli a ciprofloxacina en las mujeres ?50 años de edad. Nuestros datos muestran que existe una baja resistencia in vitro a nitrofurantoína.

Predictibilidad de la propagación espacial y temporal de la epidemia de influenza A H1N1 en la Argentina por el método de percolación

La epidemia de influenza A H1N1 se expandió rápidamente a nivel mundial dadas las actuales condiciones de alta interconectividad y velocidad de los transportes, imperantes tanto entre las personas como entre los países y las regiones. La diseminación espacial de la epidemia puede ser explicada mediante la teoría de la percolación, que permite estimar un umbral más allá del cual se produce el traspaso de la epidemia entre distintas regiones geográficas. El objetivo de este trabajo fue probar la capacidad predictiva del modelo de percolación aplicado al análisis de la epidemia de influenza A H1N1 registrada en la Argentina en 2009, de acuerdo a los datos relevados por el Ministerio de Salud Pública de la Nación. Para aplicar el mencionado modelo se consideró al país como un conjunto de figuras geométricas irregulares, contiguas y continuas, que pueden representarse en dos dimensiones en una carta geográfica plana. Se analizó la proporción de provincias infectadas en el momento de la percolación con respecto al tiempo y se compararon los valores observados con los esperados mediante ecuaciones de estimación curvilínea en un modelo logístico. La percolación ocurrió en el día 45. El valor esperado que generó el modelo fue de 42,4 días, intervalo de confianza de 95 % 28,5-56,3. La diferencia entre el valor observado y el esperado arrojó un valor de p = 0,997. Se concluye que el modelo posee un buen ajuste y una adecuada capacidad predictiva.

Spatial and temporal spread predictability of influenza A H1N1 epidemic in Argentina by the percolation method. The influenza A H1N1 epidemic has spread rapidly worldwide on account of the current conditions of high interconnectivity and transport speed both among people and countries. The spatial spread of the epidemics can be explained by the percolation theory which allows to estimate a threshold beyond which the transmission of the infection among different geographic regions occurs. The aim of this study was to test the predictive ability of the percolation model of influenza A H1N1 epidemic in Argentina according to data gathered by the National Department of Public Health. In the model, the country was considered as a set of irregular, contiguous and continuous geometric figures, which can be represented in two dimensions on a plane. We analyzed the proportion of infected provinces at the moment of percolation in relation to time in days and compared observed and expected values by curvilinear equations in a logistic model. Percolation occurred on day 45. The expected value generated by the model was 42.4 days, 95 % CI 28.5 to 56.3. The difference between observed and expected values was p = 0.997. We conclude that the model has good fit and predictive capacity.

Heterogeneous vancomycin-intermediate susceptibility in a community-associated methicillin-resistant Staphylococcus aureus epidemic clone, in a case of Infective Endocarditis in Argentina.

BACKGROUND: Community-Associated Methicillin Resistant Staphylococcus aureus (CA-MRSA) has traditionally been related to skin and soft tissue infections in healthy young patients. However, it has now emerged as responsible for severe infections worldwide, for which vancomycin is one of the mainstays of treatment. Infective endocarditis (IE) due to CA-MRSA with heterogeneous vancomycin-intermediate susceptibility-(h-VISA) has been recently reported, associated to an epidemic USA 300 CA-MRSA clone. CASE PRESENTATION: We describe the occurrence of h-VISA phenotype in a case of IE caused by a strain belonging to an epidemic CA-MRSA clone, distinct from USA300, for the first time in Argentina. The isolate h-VISA (SaB2) was recovered from a patient with persistent bacteraemia after a 7-day therapy with vancomycin, which evolved to fatal case of IE complicated with brain abscesses. The initial isolate-(SaB1) was fully vancomycin susceptible (VSSA). Although MRSA SaB2 was vancomycin susceptible (≤ 2 µg/ml) by MIC (agar and broth dilution, E-test and VITEK 2), a slight increase of MIC values between SaB1 and SaB2 isolates was detected by the four MIC methods, particularly for teicoplanin. Moreover, Sab2 was classified as h-VISA by three different screening methods [MHA5T-screening agar, Macromethod-E-test-(MET) and by GRD E-test] and confirmed by population analysis profile-(PAP). In addition, a significant increase in cell-wall thickness was revealed for SaB2 by electron microscopy. Molecular typing showed that both strains, SaB1 and SaB2, belonged to ST5 lineage, carried SCCmecIV, lacked Panton-Valentine leukocidin-(PVL) genes and had indistinguishable PFGE patterns (subtype I2), thereby confirming their isogenic nature. In addition, they were clonally related to the epidemic CA-MRSA clone (pulsotype I) detected in our country. CONCLUSIONS: This report demonstrates the ability of this epidemic CA-MRSA clone, disseminated in some regions of Argentina, to produce severe and rapidly fatal infections such as IE, in addition to its ability to acquire low-level vancomycin resistance; for these reasons, it constitutes a new challenge for the Healthcare System of this country.