Evolución de un brote epidémico por Staphylococcus aureus resistente a la meticilina (SARM)

Descripció del recurs: 16 abril 2002Títol obtingut de la portada digitalitzadaSARM se ha convertido en un patógeno nosocomial mundial en las últimas dos décadas. Desde diciembre de 1990 se ha producido en el Hospital Universitario Germans Trias i Pujol (HUGTiP) de Badalona una situación endemico-epidémica de infección por SARM. El objetivo de esta tesis doctoral es estudiar la epidemiología descriptiva, fenotípica y molecular del SARM en el HUGTiP, y analizar el impacto de las medidas de control adoptadas sobre la evolución del brote. Material y métodos: Entre diciembre de 1990 (inicio del brote) y diciembre de 1996 se registraron 462 casos de SARM en el HUGTiP, de los que se obtuvieron 119 cepas para posterior estudio fenotípico (antibiograma) y molecular (electroforesis en campo pulsante). Resultados y Conclusiones: El brote de SARM en el HUGTiP se originó en la UCI, desde donde se diseminó ampliamente al resto del hospital. La mayoría de los pacientes adquirieron el SARM en la UCI (58,1%) y en resto en las áreas de hospitalización general (AHG) (42,8%), mientras que sólo 11 casos se originaron en la comunidad (8) o en otro hospital (3). Los casos originados en las AHG se distribuyeron ampliamente en los distintos servicios médicos y quirúrgicos del hospital, mientras que el hospital materno infantil permaneció prácticamente libre de SARM. Las características de los pacientes con SARM no difieren de las de otros brotes. Doscientos dieciséis pacientes (46,7%) presentaron alguna infección por SARM, 248 (53,7%) eran portadores nasales y 169 (36,6%) estuvieron colonizados. Las infecciones más frecuentes fueron la herida quirúrgica (38,4%), la bacteriemia (19,4%) y la neumonía (13,4%). La mortalidad de las infecciones por SARM fue de 7,9% y de la bacteriemia del 19,4%. El estudio fenotípico demostró dos antibiotipos: el primero presente desde el principio del brote (resistente a los aminoglucósidos) fue sustituido progresivamente a partir de 1996 por otro sensible a los aminoglucósidos. La disminución en el consumo de aminoglucósidos en este período, podría haber favorecido la aparición de cepas sensibles a estos. El estudio molecular de las cepas de SARM demostró que el brote estuvo causado por un clon predominante, que sufrió pocas variaciones con el tiempo y tendió a ser sustituido por un segundo clon. Asimismo, existió una clara correlación entre los dos antibiotipos y los dos clones predominantes. Las medidas de control adoptadas han conseguido disminuir la incidencia de SARM en nuestro hospital, hasta una situación de endemia.In the last two decades, MRSA has become a nosocomial pathogen around the word. Since December 1990 there has been an epidemic-endemic situation of infection by MRSA, in the University Hospital Germans Trias i Pujol (HUGTiP), The aim of this doctoral thesis was to study the descriptive, phenotypic and molecular epidemiology of MRSA in the HUGTiP, and to analyze the impact of control measures in the evolution of the outbreak. Material and methods: From December 1990 (beginning of the outbreak) to December 1996, 462 cases of MRSA were registered in the HUGTiP. We also obtained 119 strains for phenotypic (antibiotic sensitivity) and molecular (pulsed field gel electrophoresis) studies. Results and Conclusions: The outbreak of SARM in the HUGTiP began in the Intensive Care Unit (ICU), and disseminated extensively in the hospital. Most of the patients were infected in ICU (58.1%) and in general hospitalization wards (42.8%), while only 11 cases originated in the community (8) or another hospital (3). MRSA was distributed extensively in most of the medical and surgical departments, while obstetric and pediatric wards remained practically free of MRSA. The characteristics of the patients were similar to those observed in others outbreaks. Two hundred and sixteen patients (64.7%) had infection by MRSA, 248 (53.7%) were nasal carriers and 169 (36.6%) were colonized. The most frequent Infections seen were surgical wound (38.4%), bacteremia (19.4%) and pneumonia (13.4%). The mortality related to infections was 7.9% and to bacteremia was 19.4%. The phenotypic study showed two antibiotypes: the first was present from the beginning of the outbreak (resistant to aminoglucosides) and was progressively substituted in 1996 by other clone sensitive to aminoglucosides. The reduction in the use of aminoglucosides in this period could have favored the appearance of resistant strains. The molecular study of MRSA strains showed that outbreak was caused by a predominant clone with few variations over time, which was progressively substituted by a second clone. On the other hand, we observed a correlation between the two antibiotypes and the two clones. Control measures have diminished the incidence of MRSA in our hospital up to the present endemic situation

Feature Selection, Ranking of Each Feature and Classification for the Diagnosis of Community Acquired Legionella Pneumonia

Diagnosis of community acquired legionella pneumonia (CALP) is currently performed by means of laboratory techniques which may delay diagnosis several hours. To determine whether ANN can categorize CALP and non-legionella community-acquired pneumonia (NLCAP) and be standard for use by clinicians, we prospectively studied 203 patients with community-acquired pneumonia (CAP) diagnosed by laboratory tests. Twenty one clinical and analytical variables were recorded to train a neural net with two classes (LCAP or NLCAP class). In this paper we deal with the problem of diagnosis, feature selection, and ranking of the features as a function of their classification importance, and the design of a classifier the criteria of maximizing the ROC (Receiving operating characteristics) area, which gives a good trade-off between true positives and false negatives. In order to guarantee the validity of the statistics; the train-validation-test databases were rotated by the jackknife technique, and a multistarting procedure was done in order to make the system insensitive to local maxima

Estudio prospectivo caso control de los factores de riesgo y pronósticos de la neumonía nosocomial en los enfermos no ventilados

Es tracta d'un estudi prospectiu cas-control realitzat a l'Hospital Germans Trias i Pujol, amb l'objectiu de determinar la incidència, els factors de risc i el pronòstic de la pneumònia nosocomial en pacients no ventilats. Els factors de risc associats a la pneumònia nosocomial van ser la insuficiència renal crònica, la malnutrició, l'anèmia, la infecció nosocomial prèvia així com el ingrés hospitalari en el darrer mes i el previ a la UCI. La malaltia de base, el risc d'aspiració, el tractament antibiòtic i la presència de complicacions es van associar amb un pitjor pronòstic.Se trata de un estudio prospectivo caso-control realizado en el Hospital Germans Trias i Pujol, cuyo objetivo fue determinar la incidencia, los factores de riesgo y el pronóstico de la neumonía nosocomial en pacientes no ventilados. Los factores de riesgo asociados a la neumonía nosocomial fueron la insuficiencia renal crónica, la malnutrición, la anemia, la infección nosocomial previa así como el ingreso hospitalario en el último mes y el previo en UCI. La enfermedad de base, el riesgo de aspiración, el tratamiento antibiótico y la presencia de complicaciones se asociaron a un peor pronóstico

Impact of a training program on the surveillance of Clostridioides difficile infection

A high degree of vigilance and appropriate diagnostic methods are required to detect Clostridioides difficile infection (CDI). We studied the effectiveness of a multimodal training program for improving CDI surveillance and prevention. Between 2011 and 2016, this program was made available to healthcare staff of acute care hospitals in Catalonia. The program included an online course, two face-to-face workshops and dissemination of recommendations on prevention and diagnosis. Adherence to the recommendations was evaluated through surveys administered to the infection control teams at the 38 participating hospitals. The incidence of CDI increased from 2.20 cases/10 000 patient-days in 2011 to 3.41 in 2016 (P < 0.001). The number of hospitals that applied an optimal diagnostic algorithm rose from 32.0% to 71.1% (P = 0.002). Hospitals that applied an optimal diagnostic algorithm reported a higher overall incidence of CDI (3.62 vs. 1.92, P < 0.001), and hospitals that were more active in searching for cases reported higher rates of hospital-acquired CDI (1.76 vs. 0.84, P < 0.001). The results suggest that the application of a multimodal training strategy was associated with a significant rise in the reporting of CDI, as well as with an increase in the application of the optimal diagnostic algorithm

Características epidemiológicas y evolución de los pacientes con bacteriemia por Staphylococcus aureus ingresados en un Hospital de tercer nivel

El objetivo del estudio fue describir las características epidemiológicas y los factores de riesgo de la bacteriemia por Staphylococcus aureus (BSA) en pacientes adultos atendidos en un hospital de tercer nivel. Se incluyeron 188 pacientes con BSA, 62 % hombres y con una edad media de 64±15,3 años. El 24% eran SARM. La mayoría provenían de servicios médicos (63,8%). El origen más frecuente de la BSA fue nosocomial (56,4%) seguido del relacionado con el ámbito sanitario (RAS) (28,7%) y comunitario (14,9 %). Presentaban enfermedad de base subyacente un 96%, siendo la más frecuente la neoplasia con un total de 65 pacientes (35 %). La enfermedad de base se consideró fatal en 38,3% pacientes, últimamente fatal en 22,3 % y no fatal en 39,4 %. El foco de infección resultó aparente en 151 pacientes (80,3%), siendo el más frecuente el catéter vascular (45,7 %). Presentaron fiebre el 73,9 %, leucocitosis un 44% y bandas en la analítica un 25%. Presentaron complicaciones el 36,2 % de los pacientes con BSA: shock (26,1%) y metástasis sépticas (14,4%). La evolución fue favorable en 126 pacientes (67%), mientras que 52 (27,7%) fallecieron, 43 de ellos (22,9%) en relación con al BSA y en 7 (3,7%) recidivó

Legionella SBT applied directly to respiratory samples as a rapid molecular epidemiological tool

Legionnaires' disease (LD) is an atypical pneumonia caused by the inhalation of Legionella. The methods used for the diagnosis of LD are direct culture of respiratory samples and urinary antigen detection. However, the sensitivity of culture is low, and the urinary antigen test is specific only for L. pneumophila sg1. Moreover, as no isolates are obtained, epidemiological studies cannot be performed. The implementation of Nested-sequence-based typing (Nested-SBT) makes it possible to carry out epidemiological studies while also confirming LD, especially in cases caused by non-sg 1. Sixty-two respiratory samples from patients with Legionella clinically confirmed by positive urinary antigen tests were cultured and tested by Nested-SBT, following the European Study Group for Legionella Infections (ESGLI) protocol. Only 2/62 (3.2%) respiratory samples were culture-positive. Amplification and sequencing of Nested-SBT genes were successfully performed in 57/62 samples (91.9%). The seven target genes were characterised in 39/57 (68.4%) respiratory samples, and the complete sequence type (ST) was obtained. The mip gene was the most frequently amplified and sequenced. Nested-SBT is a useful method for epidemiological studies in culture-negative samples, achieving a 28.7-fold improvement over the results of culture studies and reducing the time needed to obtain molecular epidemiological results

Impact of a training program on the surveillance of Clostridioiaes difficile infection

A high degree of vigilance and appropriate diagnostic methods are required to detect Clostridioides difficile infection (CDI). We studied the effectiveness of a multimodal training program for improving CDI surveillance and prevention. Between 2011 and 2016, this program was made available to healthcare staff of acute care hospitals in Catalonia. The program included an online course, two face-to-face workshops and dissemination of recommendations on prevention and diagnosis. Adherence to the recommendations was evaluated through surveys administered to the infection control teams at the 38 participating hospitals. The incidence of CDI increased from 2.20 cases/10 000 patient-days in 2011 to 3.41 in 2016 (P < 0.001). The number of hospitals that applied an optimal diagnostic algorithm rose from 32.0% to 71.1% (P = 0.002). Hospitals that applied an optimal diagnostic algorithm reported a higher overall incidence of CDI (3.62 vs. 1.92, P < 0.001), and hospitals that were more active in searching for cases reported higher rates of hospital-acquired CDI (1.76 vs. 0.84, P < 0.001). The results suggest that the application of a multimodal training strategy was associated with a significant rise in the reporting of CDI, as well as with an increase in the application of the optimal diagnostic algorithm

Correlation between Clinical and Immunological Variables and Humoral Response to SARS-CoV-2 Vaccination in Adult Patients with Antibody Deficiency Disorders

Altres ajuts: Generalitat de Catalunya's Department de salut (SLD015); Consorcio Centro de Investigación Biomédica en Red (CB-2021)Background. Prophylactic vaccination has proven to be the most effective strategy to fight the COVID-19 pandemic. Methods. This was a prospective observational cohort study involving 30 predominantly antibody deficiency disorders (ADD)-afflicted adult patients on immunoglobulin replacement therapy vaccinated with three doses of the mRNA-1273 COVID-19 vaccine, and 10 healthy controls. Anti-RBD IgG antibodies were determined in plasma samples collected just before the first dose of mRNA-based COVID-19 vaccine and on weeks 4, 8, 24, and 28 following the first vaccination. Patients were categorized based on the levels of anti-RBD antibodies determined on w8 as non-, low-, and responders. Chi-square and Kruskal-Wallis tests were used to see if any variables correlated with humoral response levels. Any adverse effects of the mRNA-based vaccine were also noted. Results. The COVID-19 vaccine was safe and well-tolerated. The humoral response elicited at w8 after vaccination depended on the type of ADD, the type of immunoglobulin deficiency, the presence of granulomatous lymphocytic interstitial lung disease, recent use of immunosuppressive drugs, and the switched memory B cells counts. The third vaccine dose boosted humoral response in previous responders to second dose but seldom in non-responders. Conclusions: The humoral response of patients with predominant ADD depends mostly on the type of immunodeficiency and on the frequency of B and T cell populations

Impact of the Introduction of a Two-Step Laboratory Diagnostic Algorithm in the Incidence and Earlier Diagnosis of Clostridioides difficile Infection

Our aim was to determine changes in the incidence of CD infection (CDI) following the introduction of a two-step diagnostic algorithm and to analyze CDI cases diagnosed in the study period. We retrospectively studied CDI (January 2009 to July 2018) in adults diagnosed by toxin enzyme immunoassay (EIA) (2009-2012) or toxin-EIA + polymerase chain reaction (PCR) algorithm (2013 onwards). A total of 443 patients with a first episode of CDI were included, 297 (67.1%) toxin-EIA-positive and 146 (32.9%) toxin-EIA-negative/PCR-positive were only identified through the two-step algorithm including the PCR test. The incidence of CDI increased from 0.9 to 4.7/10,000 patient-days (p < 0.01) and 146 (32.9%) toxin-negative CDI were diagnosed. Testing rate increased from 24.4 to 59.5/10,000 patient-days (p < 0.01) and the percentage of positive stools rose from 3.9% to 12.5% (p < 0.01). CD toxin-positive patients had a higher frequency of severe presentation and a lower rate of immunosuppressive drugs and inflammatory bowel disease. Mortality (16.3%) was significantly higher in patients with hematological neoplasm, intensive care unit admission and complicated disease. Recurrences (14.9%) were significantly higher with proton pump inhibitor exposure. The two-step diagnostic algorithm facilitates earlier diagnosis, potentially impacting patient outcomes and nosocomial spread. CD-toxin-positive patients had a more severe clinical presentation, probably due to increased CD bacterial load with higher toxin concentration. This early and easy marker should alert clinicians of potentially more severe outcomes

Evaluation of Fourier Transform Infrared Spectroscopy as a First-Line Typing Tool for the Identification of Extended-Spectrum β-Lactamase-Producing Klebsiella pneumoniae Outbreaks in the Hospital Setting

Early detection of pathogen cross-transmission events and environmental reservoirs is needed to control derived nosocomial outbreaks. Whole-genome sequencing (WGS) is considered the gold standard for outbreak confirmation, but, in most cases, it is time-consuming and has elevated costs. Consequently, the timely incorporation of WGS results to conventional epidemiology (CE) investigations for rapid outbreak detection is scarce. Fourier transform infrared spectroscopy (FTIR) is a rapid technique that establishes similarity among bacteria based on the comparison of infrared light absorption patterns of bacterial polysaccharides and has been used as a typing tool in recent studies. The aim of the present study was to evaluate the performance of the FTIR as a first-line typing tool for the identification of extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-Kp) outbreaks in the hospital setting in comparison with CE investigations using WGS as the gold standard method. Sixty-three isolates of ESBL-Kp collected from 2018 to 2021 and classified according to CE were typed by both FTIR and WGS. Concordance was measured using the Adjusted Rand index (AR) and the Adjusted Wallace coefficient (AW) for both CE and FTIR clustering considering WGS as the reference method. Both AR and AW were significantly higher for FTIR clustering than CE clustering (0.475 vs. 0.134, p = 0.01, and 0.521 vs. 0.134, p = 0.009, respectively). Accordingly, FTIR inferred more true clustering relationships than CE (38/42 vs. 24/42, p = 0.001). However, a similar proportion of genomic singletons was detected by both FTIR and CE (13/21 vs. 12/21, p = 1). This study demonstrates the utility of the FTIR method as a quick, low-cost, first-line tool for the detection of ESBL-Kp outbreaks, while WGS analyses are being performed for outbreak confirmation and isolate characterization. Thus, clinical microbiology laboratories would benefit from integrating the FTIR method into CE investigations for infection control measures in the hospital setting