A.M. Planes

Value of differential quantitative blood cultures in the diagnosis of catheter-related sepsis

A prospective study was performed to assess the value of differential quantitative blood cultures in the diagnosis of catheter-related sepsis when this condition is suspected on clinical grounds and to establish a reliable discriminative value for application without removal of the inserted catheter. A total of 107 central venous catheters from 64 patients were used for the study. Blood was obtained simultaneously through the suspected infected device and from a peripheral venipuncture. The catheter was removed and its tip cultured semiquantitatively. Catheter-related sepsis occurred in 17 patients. Using as cut-off value a colony count fourfold higher in blood drawn through the catheter than in simultaneously drawn peripheral blood, a sensitivity of 94 %, specificity of 100 % and positive predictive value of 100 % were obtained. A single bacterial count > 100 cfu/ml in the quantitative culture of the catheter blood specimen in the presence of a positive qualitative peripheral blood culture of the same organism was also highly suggestive of catheter-related sepsis. Differential quantitative blood culture is a reliable method for the diagnosis of catheter-associated sepsis without catheter removal.

Immediate and long-term outcome of left-sided infective endocarditis. A 12-year prospective study from a contemporary cohort in a referral hospital

The aim of this study was to describe the immediate and long-term prognosis of a contemporary cohort of patients with left-sided infective endocarditis (LSIE). A prospective observational cohort study was conducted in a referral centre. Between January 2000 and December 2011, all consecutive adult patients with LSIE were followed-up until death, relapse, recurrence, need for late surgery, or last control. During the active phase of IE, 174 of 438 patients underwent surgery (40% overall; 43% native valve (NVIE), 30% prosthetic valve (PVIE)) and 125 died (29% overall; 26% NVIE, 39% PVIE). The median follow-up in survivors was 3.2 years (interquartile range (IQR) 1.0-6.0 years). Relapses occurred in seven patients (2.2%; 95% CI, 1.1-4.5) and recurrences in eight (2.6%; 95% CI, 1.3-5.0), with an incidence density of 0.0067 per patient-year (95% CI, 0.0029-0.0133) and high mortality (75% of recurrences). Only four of 130 survivors (3.1%; 95% CI, 1.2-7.6) who were treated surgically during the active phase of the disease, and 14/183 (7.7%; 95% CI, 4.6-12.4) of those not undergoing surgery needed operation during follow-up (p 0.09). In the 313 survivors, actuarial survival was 86% at 1 year (87% NVIE, 83% PVIE), 79% at 2 years (81% NVIE, 72% PVIE) and 68% at 5 years (71% NVIE, 57% PVIE). At 1 year, 115 of 397 patients (29.0%; 95% CI, 24.7-33.6) remained alive, with no surgery requirement, relapse or recurrence. LSIE is associated with considerable in-hospital and long-term mortality, especially PVIE. However, relapses, recurrences and the need for late surgery are uncommon.

Effects of Immunocompromise and Comorbidities on Pneumococcal Serotypes Causing Invasive Respiratory Infection in Adults: Implications for Vaccine Strategies

BACKGROUND The 13-valent pneumococcal conjugate vaccine (PCV13) has recently been approved for use in immunocompromised adults. However, it is unclear whether there is an association between specific underlying conditions and infection by individual serotypes. The objective was to determine the prevalence of serotypes covered by PCV13 in a cohort of patients with invasive pneumococcal disease of respiratory origin and to determine whether there are specific risk factors for each serotype. METHODS An observational study of adults hospitalized with invasive pneumococcal disease in 2 Spanish hospitals was conducted during the period 1996-2011. A multinomial regression analysis was performed to identify conditions associated with infection by specific serotypes (grouped according their formulation in vaccines and individually). RESULTS A total of 1094 patients were enrolled; the infecting serotype was determined in 993. In immunocompromised patients, 64% of infecting serotypes were covered by PCV13. After adjusting for age, smoking, alcohol abuse, and nonimmunocompromising comorbidities, the group of serotypes not included in either PCV13 or PPV23 were more frequently isolated in patients with immunocompromising conditions and cardiopulmonary comorbidities. Regarding individual serotypes, 6A, 23F, 11A, and 33F were isolated more frequently in patients with immunocompromise and specifically in some of their subgroups. The subgroup analysis showed that serotype10A was also associated with HIV infection. CONCLUSIONS Specific factors related to immunocompromise seem to determine the appearance of invasive infection by specific pneumococcal serotypes. Although the coverage of serotypes in the 13-valent conjugate pneumococcal vaccine (PCV13) was high, some non-PCV13-emergent serotypes are more prevalent in immunocompromised patients.

Impact of the emergence of non-vaccine pneumococcal serotypes on the clinical presentation and outcome of adults with invasive pneumococcal pneumonia

The introduction of the 7-valent pneumococcal conjugate vaccine in children has led to a change in the pattern of pneumococcal serotypes causing pneumococcal disease. The aim of this study was to compare the clinical presentation and outcome of invasive pneumococcal pneumonia (IPP) in adults between the pre and post-vaccine era. We have conducted an observational study of all adults hospitalized with IPP, from 1996 to 2001 (pre-vaccine period), and from 2005 to 2009 (post-vaccine period). Incidence, serotype distribution and clinical data were compared between both periods. A total of 653 episodes of IPP were diagnosed. The overall incidence of IPP increased from 14.2 to 17.9 cases per 100 000 population-year (p 0.003). In the post-vaccine period IPP caused by vaccine serotypes decreased (-36%; 95% CI, -52 to -15) while IPP caused by non-vaccine serotypes increased (71%; 95% CI, 41-106). IPP in the post-vaccine period was associated with higher rates of septic shock (19.1% vs. 31.1%, p <0.001). Among patients aged 50-65 years there was a trend towards a greater proportion of case-fatalities (11.6-23.5%, p 0.087). Independent risk factors for septic shock were IPP caused by serotype 3 (OR 2.38; 95% CI, 1.16-4.87) and serotype 19A (OR 6.47, 95% CI, 1.55-27). Serotype 1 was associated with a lower risk of death (OR 0.1; 95% CI, 0.01-0.78). In conclusion, the incidence of IPP in the post-vaccine period has increased in our setting, it is caused mainly by non-vaccine serotypes and it is associated with higher rates of septic shock.

Effectiveness of antibiotic-lock therapy for long-term catheter-related bacteremia due to Gram-negative bacilli: a prospective observational study.

A prospective observational study evaluated the effectiveness of combining antibiotic-lock therapy and systemic antibiotics for Gram-negative bacilli long-term catheter-related bacteremia. In 46 uncomplicated episodes, the most frequently isolated microorganisms were Pseudomonas aeruginosa (15), Enterobacter cloacae (12), Escherichia coli (10), and Klebsiella spp. (8). Cure was achieved in 95% of cases.

Evaluation of the usefulness of a quantitative blood culture in the diagnosis of catheter-related bloodstream infection: Comparative analysis of two periods (2002 and 2012)

INTRODUCTION A retrospective study was conducted to investigate the usefulness of systematic quantitative blood culture (QBC) in the diagnosis of catheter-related bloodstream infection (CRBSI) during two 1-year periods (2002 and 2012). METHODS The study included all QBC requests sent to the microbiology laboratory for suspected CRBSI in adults (≥18 years) with any type of intravascular catheter (IVC). Based on a ratio of ≥4:1CFU/mL of the same microorganism between IVC blood culture from any lumen and peripheral blood culture, 5 diagnostic groups were defined: confirmed or probable CRBSI, primary BSI, other focus of infection, and colonization. RESULTS In total, 4521 QBCs were evaluated; 24% positive in 2002 and 16% in 2012 (P<0.0001). There were 243 episodes of suspected CRBSI (101 in 2002 and 142 in 2012). Confirmed CRBSI episodes were higher in 2002 than 2012 (56% vs 34%) (P<0.0001), whereas colonization episodes were lower (18% vs 38%) (P=0.0006). Gram-positive cocci decrease in 2012 relative to 2002 (56% vs 79.7%) (P=0.022). Almost one-third (32%) of confirmed CRBSI would have been missed if blood from all catheter lumens had not been cultured. CONCLUSIONS QBC is a useful method for diagnosing CRBSI. Blood samples from all catheter lumens must be cultured to avoid missing around one-third of CRBSI diagnoses.

Evolución de la sepsis perinatal por Escherichia coli en la era de la profilaxis del estreptococo del grupo B

Fundamento Caracterizar la sepsis perinatal precoz por Escherichia coli y analizar su posible correlacion con la implantacion de la profilaxis del estreptococo del grupo b (egb). Pacientes y metodo Entre 1994 y 2000, 24 neonatos nacidos en nuestro centro fueron diagnosticados de sepsis perinatal por e. coli; 12 procedian de madres cuyo embarazo fue controlado en nuestro centro y 12 de madres remitidas poco antes del parto. Ademas se diagnosticaron otras tres sepsis perinatales por e. coli en ninos remitidos con posterioridad a su nacimiento. Resultados La incidencia anual no cambio significativamente (riesgo relativo [rr] 1,065; intervalo de confianza [ic] del 95%, –0,873 a 1,301; p = 0,533), oscilando del 0,6‰ en 1994 al 1,7‰ en 1997 y al 0,5‰ en 2000. El 92% de las madres presentaron factores de riesgo obstetrico: el 68% parto prematuro (media: 32,9 semanas; mediana: 32), el 64% rotura prolongada de membrana (media: 184 h; mediana: 44), y el 56% fiebre intraparto. El 12% de las gestantes recibieron ampicilina intraparto como profilaxis de la sepsis por egb y el 80% antibioterapia: 6 como profilaxis de la rotura de membranas, 6 como tratamiento de su infeccion urinaria y 8 como tratamiento de una posible corioamnionitis. El 81% de e. coli aislados en los neonatos fueron resistentes a la ampicilina. No se ha encontrado relacion entre e. coli resistente a ampicilina y prematuridad (p = 0,57), rotura de membranas (p = 0,63), fiebre intraparto (p = 0,24) o fallecimiento (p = 0,53). Conclusiones Estos resultados sugieren que la sepsis perinatal por e. coli no esta relacionada con la aplicacion de medidas profilacticas contra egb, sino con la prematuridad, la prolongacion del embarazo en la rotura prematura de membranas y exposicion a la antibioterapia que todo ello comporta.

Utilidad del frasco anaerobio en el diagnóstico de bacteriemia o fungemia

El hemocultivo sigue siendo la piedra angular del diagnóstico de la bacteriemia o fungemia, a pesar del desarrollo de nuevas técnicas, como la detección de antı́geno, la hibridación y la PCR (polymerase chain reaction ‘reacción en cadena de la polimerasa’). El aumento de pacientes trasplantados, inmunodeprimidos, neoplásicos y portadores de material protésico (catéteres intravasculares [CIV], prótesis valvulares o marcapasos) ha dado lugar a un incremento del número de hemocultivos procesados en el laboratorio. A pesar de la generalización de los sistemas automáticos, concebidos para mejorar la sensibilidad y acortar el tiempo entre la sospecha y la detección de la bacteriemia, no se ha incrementado de forma significativa el porcentaje de positividad de éstos. Las condiciones necesarias para diagnosticar una bacteriemia o fungemia están muy bien establecidas en lo que se refiere a las medidas de asepsia de la técnica de extracción, el número de extracciones, el intervalo entre éstas y el volumen de sangre necesario por hemocultivo. Habitualmente, un hemocultivo consta de una pareja de frascos: uno aerobio (que permite el crecimiento de microorganismos aerobios y de anaerobios facultativos) y otro anaerobio (donde crecen los anaerobios estrictos y también los facultativos), o bien un frasco pediátrico (aerobio) para menores de 2 años. Actualmente, se dispone de una gran variedad de frascos de hemocultivos preparados con diferentes nutrientes y atmósferas adecuadas para aerobios, microaerófilos, anaerobios estrictos, micobacterias y hongos; los hay también con sustancias como resinas o carbón activado, a las que se adhieren algunos antimicrobianos neutralizando su actividad in vitro. La bacteriemia por anaerobios es poco frecuente, como comentan Ruiz-Giardı́n et al en este número, y los datos de incidencia que ellos revisan son muy diversos. Se puede sospechar su participación en el proceso infeccioso ante un foco abdominal o ante un foco ginecológico, pero no siempre es evidente. Blairon et al lo desconocen en el 20% de los episodios, estos mismos autores encuentran como factores de riesgo más importantes la cirugı́a del tracto gastrointestinal y las neoplasias hematológicas activas con tratamiento quimioterápico o con trasplante de médula ósea. La quimioterapia es un factor predisponente debido a la inflamación y a la ulceración intestinal, ya que la lesión de las barreras mucosas proporciona una puerta de entrada para la