When is coagulase-negative Staphylococcus bacteraemia clinically significant?

BACKGROUND: Coagulase-negative staphylococci (CoNS) are common contaminants in blood cultures (BC). A prospective study of patients with ≥ 2 blood culture sets and at least 1 positive CoNS BC was performed to develop an algorithm to assist in determining the clinical significance of CoNS bacteraemia. METHODS: A single reviewer examined the medical records of patients with CoNS bacteraemia (January-June 2010). The determination of clinical significance was made according to CDC/NHSN (US Centers for Disease Control and Prevention/National Healthcare Safety Network) criteria. To explore risk factors associated with clinical significance, a multivariate analysis was performed. The performances of various algorithms were then compared. An algorithm to assist in determining clinical significance was developed. RESULTS: Two hundred and sixty-nine cases were included; 97 (36%) were considered clinically significant bacteraemia (CSB). Predictors of CSB in the multivariate analysis were: time to positivity < 16 h (odds ratio (OR) 4.540, 95% confidence interval (CI) 1.734-11.884), identification of Staphylococcus epidermidis (OR 4.273, 95% CI 2.124-5.593), central venous catheter (OR 4.932, 95% CI 2.467-9.858), > 2 CoNS-positive bottles from different BC sets (OR 1.957, 95% CI 1.401-2.733), and Charlson score ≥ 3 (OR 2.102, 95% CI 1.078-4.099). The algorithm with best sensitivity (62%) and specificity (93%) for determining clinical significance of CoNS included Charlson score ≥ 3, Pitt score ≥ 1, neutropenic patients, presence of central venous catheter, identification of S. epidermidis, and time to positivity < 16 h. The positive predictive value was 83% and the negative predictive value was 81% (likelihood ratio 8.87). CONCLUSION: The use of this algorithm could potentially reduce the misclassification of nosocomial bloodstream infections and inappropriate antibiotic treatment in patients for whom a positive CoNS does not represent a CSB.

Bacteriemias por Staphylococcus coagulasa negativa: análisis de factores pronóstico e influencia del tratamiento antibiótico / Coagulase-negative Staphylococcus bacteraemia: prognosis factors and influence of antibiotic treatment

Introducción: Staphylococcus coagulasa negativa (SCN) es el microorganismo que se aisla con mayor frecuencia en los hemocultivos (HC) obtenidos en pacientes hospitalizados; su pronóstico se ha asociado a la gravedad clínica del paciente así como a un tratamiento antibiótico empírico inadecuado pero en la actualidad la influencia del tratamiento antibiótico empírico adecuado en la supervivencia de los enfermos no representa un factor pronóstico claramente reconocido. Los objetivos del estudio fueron analizar los factores asociados a una mayor mortalidad en pacientes con bacteriemia por SCN y la influencia del tratamiento antibiótico empírico en su evolución. Pacientes y método: análisis prospectivo (enero a junio de 2010) de los pacientes con HC positivos para SCN en un centro hospitalario universitario; se clasificó la bacteriemia como verdadera atendiendo a criterios de los CDC y se evaluaron los parámetros epidemiológicos, clínicos y microbiológicos relacionados con el fallecimiento del paciente. Resultados: se incluyeron 269 casos en el estudio (97 bacteriemias verdaderas); el 92% de los pacientes evolucionó hacia la curación y el 8% fallecieron (el 1,6% de los fallecimientos se consideró relacionado con la bacteriemia por SCN). Staphylococcus epidermidis fue el SCN identificado con más frecuencia. En el estudio de mortalidad relacionada se incluyeron 93 casos de bacteriemia verdadera. Se asociaron de forma estadísticamente significativa al fallecimiento de los pacientes (estudio bivariante) la gravedad clínica del enfermo (Winston I-III), el ser portador de marcapasos, el desarrollo de sepsis o endocarditis infecciosa y la bacteriemia persistente. El tratamiento empírico adecuado no se asoció a una mayor supervivencia. Conclusiones: el pronóstico de los enfermos con bacteriemia por SCN se asocia a la gravedad y las complicaciones sépticas desarrolladas, siendo mayor en pacientes portadores de marcapasos; en nuestra experiencia el tratamiento empírico inadecuado no se asocia a mortalidad(AU)

Introduction: Coagulase-negative staphylococci (CNS) are the most frequent isolated microorganism in blood cultures; mortality has been associated to severity and to adequacy of empirical treatment but the relevance of the latter is not clearly recognised. The aims of the study were to analyze clinical and microbiological factors related to mortality in patients with CNS bacteraemia and the influence of empirical treatment in prognosis. Patients and methods: a prospective cohort study of patients with CNS bacteraemia was performed (January to June 2010) at a university-affiliated hospital; a determination of clinical significance was made and true bacteraemia was defined according to CDC criteria. We analysed epidemiological, clinical and microbiological variables related to mortality. Results: a total of 269 cases were included (97 were considered true bacteraemia); 92% survived and mortality was 8% (1.6% CNS bacteraemia related mortality). Staphylococcus epidermidis was the most frequent isolated species; 93 patients were included in the related mortality study of patients with true bacteraemia. Factors associated to mortality in the bivariate analysis (p<0.05) were: Winton score I-III, presence of pacemakers, sepsis or infective endocarditis and persistent bacteraemia. Adequate empirical treatment was not associated to survival. Conclusions: severity at onset, the development of septic complications and having a pacemaker are associated to mortality in patients with CNS bacteraemia; in our cohort, inadequate empirical treatment is not related to mortality(AU)

[Carbapenem and multidrug-resistant Acinetobacter baumannii colonisation/infection: epidemiology and factors associated with infection]. / Colonización/infección por Acinetobacter baumannii multirresistente y resistente a carbapenémicos: epidemiología y factores predictivos de infección.

BACKGROUND AND OBJECTIVE: To study an outbreak of nosocomial colonisation/infection due to multidrug and carbapenem resistant A. baumannii (ABMDR-C). PATIENTS AND METHODS: Prospective study of patients with ABMDR-C colonisation/infection (January 2007-June 2008). Epidemiological and clinical variables and predictors of infection versus colonization were analysed. RESULTS: 24 out of 101 cases were considered colonisations and 77 infections (27 bacteraemia); global mortality (colonisations and infections) was 42% (4 colonisations and 38 infections -18 bacteraemia). All together, the incidence was 3.2/1000 admissions/day; 29% had been previously admitted and 79% had received previous antibiotic treatment (29% carbapenem; 34% piperacillin-tazobactam; 12.5% both); 78% had an underlying condition; 81% were UCI patients; 90% had gone through invasive procedures; 65% had another microorganism isolated. In multivariate analysis, infection predictor factors were isolation of ABMDR-C in respiratory samples (OR 5.406; 95% CI 1.419-20.599); male patients (OR 8.842; 95% CI 1.988-39.325); previous hospitalization (OR 9.720; 95% CI 1.383-68.291) and initial clinical severity (OR 30.897; 95% CI 5.533-172.543). CONCLUSIONS: Our cohort of patients with ABMDR-C colonisation/infection is characterised by their underlying comorbidity, the high rate of previous invasive procedures, previous hospitalisation and previous broad-spectrum betalactam treatments (especially carbapenem). Initial severity and respiratory samples with ABMDR-C isolates were predictors of infection versus colonisation.

Hyperlipidemic chicken as a model of non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH) is part of the spectrum of non-alcoholic fatty liver disease (NAFLD), currently the most common cause of abnormal liver tests. Given the difficulty of studying all the factors involved in it in human populations, studies in animal models might provide crucial insights in the pathogenesis of steatohepatitis. Several physiological features predispose birds to fat deposition in the liver. The present study was conceived to explore the possibilities of the chicken fed a cholesterol and fat enriched diet as a model for steatohepatitis. We used two different diets: a standard growing mash (control group) and a standard growing mash enriched with 2% cholesterol and 20% palm oil (hyperlipidemic group). We investigated the effect of feeding a cholesterol and fat enriched diet, on plasma lipid levels, liver enzymes and hepatic histopathology. Semiquantitative and quantitative assessment by image analysis was performed to determine changes in lipid deposits and inflammatory infiltration. Statistically significant increases were observed in all plasma lipid parameters, liver macroscopic features, fat deposits and cell-ballooning of hepatocytes between control and hyperlipidemic animals. Significant differences were also observed in the inflammatory infiltration parameters (number of foci, density, area and maximal diameter). Results show that diet-induced hypercholesterolemia and hypertriglyceridemia are associated with severe impairment of liver histology (fat accumulation, inflammation and cell-ballooning), reproducing histological features of human NAFLD. This model, which is easy and reproducible, offers economic and technical advantages. Furthermore, the reversibility of the pathologic changes makes it suitable for drug intervention studies of steatohepatitis.