2016 Expert consensus document on prevention, diagnosis and treatment of short-term peripheral venous catheter-related infections in adult.

The use of endovascular catheters is a routine practice in secondary and tertiary care level hospitals. Short peripheral catheters have been found to be associated with the risk of nosocomial bacteremia resulting in morbidity and mortality. Staphyloccus aureus is mostly associated with peripheral catheter insertion. This Consensus Document has been elaborated by a panel of experts of the Spanish Society of Cardiovascular Infections in cooperation with experts from the Spanish Society of Internal Medicine, Spanish Society of Chemotherapy and Spanish Society of Thoracic-Cardiovascular Surgery and aims at define and establish the norm for management of short duration peripheral vascular catheters. The document addresses the indications for insertion, catheter maintenance and registry, diagnosis and treatment of infection, indications for removal and stresses on continuous education as a driver for quality. Implementation of this norm will allow uniformity in usage thus minimizing the risk of infection and its complications.

The search for endocarditis in patients with candidemia: a systematic recommendation for echocardiography? A prospective cohort.

Most current guidelines do not recommend systematic screening with echocardiography in patients with candidemia, as Candida infective endocarditis (CIE) is considered an uncommon disease. During the study period, we recommended echocardiography systematically to all candidemic patients that did not have contraindications and accepted to participate in the study. We intended to assess the incidence of unrecognized CIE in adult patients with candidemia. Our institution is a tertiary teaching hospital in which we follow all patients with candidemia. From January 2007 to October 2012, echocardiography was systematically recommended to suitable candidates. We recorded 263 cases of candidemia in adult patients. Echocardiography was not performed in 76 of these patients for the following reasons: patients had died when blood cultures became positive (17), patients were critically or terminally ill (38), or the patient or physician refused the procedure (21). The remaining 187 patients constitute the basis of this report. CIE was diagnosed in 11 cases (4.2 % of the whole candidemic population and 5.9 % of the population with echocardiographic study). The results of transthoracic echocardiography (TTE) suggested infective endocarditis (IE) in 5/172 patients (2.9 %), and the result of transesophageal echocardiography (TEE) was positive in 10/87 (11.5 %). Among 11 confirmed cases of CIE, the disease was clinically unsuspected in three patients. At least 4.2 % of all candidemic patients have CIE. CIE is frequently clinically unsuspected and echocardiography is required to demonstrate a high proportion of cases.

Is Clostridium difficile infection an increasingly common severe disease in adult intensive care units? A 10-year experience.

PURPOSE: Despite the high concentration of patients with known risk factors for Clostridium difficile infection (CDI) in intensive care units (ICUs), data on ICU patients are scarce. The aim of this study was describe the incidence, clinical characteristics, and evolution of CDI in critically ill patients. MATERIALS AND METHODS: From 2003 to 2012, adult patients admitted to an ICU (A-ICU) and positive for CDI were included and classified as follows: pre-ICU, if the positive sample was obtained within ±3 days of ICU admission; in-ICU, if obtained after 3 days of ICU admission and up to 3 days after ICU discharge. RESULTS: We recorded 4095 CDI episodes, of which 328 were A-ICU (8%). Episodes of A-ICU decreased from 19.4 to 8.7 per 10000 ICU days of stay (P < .0001). Most A-ICU CDIs (66.3%) were mild to moderate. Pre-ICU episodes accounted for 16.2% and were more severe complicated than in-ICU episodes (11% vs 0%; P = .020). Overall mortality was 28.6%, and CDI-attributable mortality was only 3%. CONCLUSION: The incidence of A-ICU CDI has decreased steadily over the last 10 years. A significant proportion of A-ICU CDI episodes are pre-ICU and are more severe than in-ICU CDI episodes. Most episodes of A-ICU CDI were nonsevere, with low associated mortality.

Uncommon aetiological agents of catheter-related bloodstream infections.

The clinical and microbiological characteristics of catheter-related bloodstream infection (CR-BSI) due to uncommon microorganisms was assessed in a retrospective case-control study over a 9-year period in a tertiary teaching hospital. Uncommon microorganisms were defined as those representing <0·5% of all CR-BSI. Diagnosis of CR-BSI required that the same microorganism was grown from at least one peripheral venous blood culture and a catheter tip culture. Thirty-one episodes of CR-BSI were identified due to 13 different genera and these accounted for 2·3% of all CR-BSI in the hospital. Although these infections were not associated with increased mortality, they occurred in patients with more severe underlying conditions who were receiving prolonged antibiotic therapy.

Direct identification of pathogens from positive blood cultures using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry.

In recent years, matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) has proved a rapid and reliable method for the identification of bacteria and yeasts that have already been isolated. The objective of this study was to evaluate this technology as a routine method for the identification of microorganisms directly from blood culture bottles (BCBs), before isolation, in a large collection of samples. For this purpose, 1000 positive BCBs containing 1085 microorganisms have been analysed by conventional phenotypic methods and by MALDI-TOF MS. Discrepancies have been resolved using molecular methods: the amplification and sequencing of the 16S rRNA gene or the Superoxide Dismutase gene (sodA) for streptococcal isolates. MALDI-TOF predicted a species- or genus-level identification of 81.4% of the analysed microorganisms. The analysis by episode yielded a complete identification of 814 out of 1000 analysed episodes (81.4%). MALDI-TOF identification is available for clinicians within hours of a working shift, as oppose to 18 h later when conventional identification methods are performed. Moreover, although further improvement of sample preparation for polymicrobial BCBs is required, the identification of more than one pathogen in the same BCB provides a valuable indication of unexpected pathogens when their presence may remain undetected in Gram staining. Implementation of MALDI-TOF identification directly from the BCB provides a rapid and reliable identification of the causal pathogen within hours.

The risk of catheter-related bloodstream infection after withdrawal of colonized catheters is low.

Most episodes of catheter-related bloodstream infection (C-RBSI) are documented before or at the time of catheter withdrawal. The risk of C-RBSI in the period after removing a colonized catheter in patients without bacteremia (late C-RBSI) is unknown. We assessed the risk of developing a late C-RBSI episode in an unselected population with positive catheter tip cultures and analyzed associated risk factors. We analyzed retrospectively all colonized catheter tips between 2003 and 2010 and matched them with blood cultures. C-RBSI episodes were classified as early C-RBSI (positive blood cultures were obtained ≤24 h after catheter withdrawal) or late C-RBSI (positive blood cultures were obtained ≥24 h after catheter withdrawal). We analyzed the risk factors associated with late C-RBSI episodes by comparison with a selected group of early C-RBSI episodes. We collected a total of 17,981 catheter tips: 4,533 (25.2 %) were colonized. Of them, 1,063 (23.5 %) were associated to early C-RBSI episodes and from the remaining 3,470, only 143 (4.1 %) were associated to late C-RBSI episodes. Then, they corresponded to 11.9 % of the total 1,206 C-RBSI episodes. After comparing early and late C-RBSI episodes, we found that late C-RBSI was significantly associated with the presence of methicillin-resistant Staphylococcus aureus (MRSA, p = 0.028) and with higher mortality (p = 0.030). According to our data, patients with colonized catheter tips had a 4.1 % risk of developing late C-RBSI, which was associated with higher crude mortality.

Catheter-related bloodstream infections caused by Gram-negative bacteria.

From 2008 to 2010, patients with microbiologically confirmed Gram-negative catheter-related bloodstream infection (GN-CRBSI) were each compared with two randomly selected controls. We included 81 cases (17% of all CRBSI) and 162 controls with CRBSI caused by other pathogens. Incidence of GN-CRBSI was 0.53 episodes per 1000 admissions. Cases were more likely to have underlying neurological disease or gastrointestinal conditions, previous antimicrobial therapy and a shorter time to blood culture positivity. Surgery in the present admission (odds ratio: 3.5), P. aeruginosa (3.6) and a complicated bacteraemia (4.1) were related to a higher mortality rate. GN-CRBSI accounts for 17% of all CRBSI and should be taken into consideration in the empirical therapy of patients with the characteristics mentioned above.

Bloodstream infections in patients with kidney disease: risk factors for poor outcome and mortality.

BACKGROUND: Information regarding bloodstream infections (BSIs) in patients with kidney diseases is scarce and mainly derived from selected groups of patients. AIM: To assess the characteristics of BSI in an unselected population of patients with kidney disease, including renal transplant recipients and patients with chronic kidney failure who were receiving or not receiving dialysis. METHODS: A retrospective cohort study of all patients who presented with BSI in the nephrology department of a large teaching hospital. Clinical records were reviewed according to a pre-established protocol. Standard definitions were used. FINDINGS: In all, 155 episodes of BSI were recorded in 108 patients. The incidence of BSI was 77.3 episodes per 1000 admissions, and 4.5 episodes per 100 patient-years. Haemodialysis patients had the highest incidence of BSI. The distribution of micro-organisms was as follows: Gram-negative, 52.3%; Gram-positive, 46.5%; fungi, 1.2%. Escherichia coli was the most frequently isolated micro-organism (27%). The BSI was classed as bacteraemia of unknown source (29.7%), urinary tract infection (23.2%), vascular access infection (17.4%), and other (29.7%). Eighteen patients (11.6%) developed septic shock or multi-organ failure, and the same proportion had persistent bacteraemia. The crude mortality rate was 14.6%. The risk factors for mortality were high Charlson index, persistent bacteraemia, and absence of fever. CONCLUSION: Nephrology patients have a high incidence of BSI, particularly patients undergoing haemodialysis. The predominant micro-organisms causing BSI episodes were Gram-negative bacilli. Patients with kidney disease have high BSI-related morbidity and mortality. Risk factors for mortality were high Charlson comorbidity index and persistent BSI. The presence of fever during the BSI episodes was found to be a protective factor.

Evolution and aetiological shift of catheter-related bloodstream infection in a whole institution: the microbiology department may act as a watchtower.

The incidence of central-line-associated bloodstream infection (CLA-BSI) is reported per 1000 days of catheter exposure, mainly in the intensive care unit (ICU), because recording exposure throughout an institution is not always feasible. Confirmation of catheter-related bloodstream infection (CR-BSI) requires specific laboratory testing that identifies the catheter as the source of infection. This information is available in microbiology laboratories and can be assessed using a denominator of 1000 admissions. We evaluated recent trends in the incidence and aetiology of CR-BSI and compared adult ICUs with the remaining areas of the hospital in a retrospective cohort analysis of all confirmed CR-BSIs. During the 8-year study period, we recorded 1208 episodes (8.2% of BSIs) of CR-BSI. After adjusting for the blood cultures drawn, a significant reduction in incidence was observed in adult ICUs (47%), where care bundles had been applied. The reduction was similar irrespective of whether CLA-BSI or CR-BSI was assessed. We recorded a significant reduction in the incidence of Staphylococcus aureus CR-BSI, and a significant increase in the incidence of CR-BSI caused by Enterococcus sp., Gram-negative microorganisms and fungi. The microbiology department may complement CLA-BSI/1000 catheter-days by providing CR-BSI when days of exposure are not available, because both figures are parallel. We demonstrated a significant reduction in the incidence of CR-BSI in recent years in the population admitted to adult ICUs but not in the remaining areas of the hospital. A shift in the aetiological spectrum of CR-BSI may be occurring.

Can microbiologists help to assess catheter involvement in candidaemic patients before removal?

We compared the efficacy of three techniques--minimal time to positivity (MTTP) of blood cultures (BCs), differential time to positivity (DTTP) of BCs obtained from the catheter and peripheral veins and the number of positive BCs--in predicting catheter involvement in patients with well-demonstrated catheter-related candidaemia (C-RC) and non-catheter-related candidaemia (NC-RC).C-RC was defined as isolation of the same Candida species from blood and catheter tip culture (≥15 cfu/plate). A ROC curve was created for each quantitative variable to determine the best cut-off for predicting C-RC.A total of 108 episodes of candidaemia were included (84 adults and 24 children; 67 C-RC and 41 NC-RC). These were caused mainly by C. albicans (49.1%) and C. parapsilosis (30.6%). The MTTP was significantly shorter in adult patients with C-RC than in those with NC-RC (29.8 vs. 36.8 hours; p 0.035), although no cut-off value provided acceptable accuracy. DTTP had high sensitivity but low specificity for predicting CRC. However, C-RC episodes had a significantly greater number of positive BCs than NC-RC episodes. The optimal cut-off for predicting C-RC was at least two positive BCs out of three, with the following validity values: sensitivity, 100%; specificity, 62.5%; positive predictive value, 83.3%; negative predictive value, 100%; accuracy, 87.0%.None of the tests evaluated allow a clear-cut prediction of C-RC and the criteria accepted for bacteraemia should not be automatically extrapolated to candidaemia. We found that a low number of positive BCs with Candida had a high negative predictive value for a catheter origin.

Catheter-related bloodstream infection caused by Enterococcus spp.

The role of Enterococcus spp. as a cause of catheter-related bloodstream infections (CR-BSI) is almost unexplored. We assessed the incidence and clinical characteristics of enterococcal CR-BSI (ECR-BSI) over an 8-year period in our hospital. We performed a retrospective study (January 2003 to December 2010) in a large teaching institution. We recorded the incidence, and the microbiological and clinical data from patients with ECR-BSI. The incidence per 10,000 admissions for enterococcal BSI and ECR-BSI was 25 and 1.7, respectively. ECR-BSI was the fourth leading cause of CR-BSI in our institution (6%). A total of 75 episodes of ECR-BSI were detected in 73 patients (6% of all enterococcal BSI). The incidence of ECR-BSI increased by 17% annually (95% CI 19.0-21.0%) during the study period. Nineteen percent of ECR-BSI episodes were polymicrobial. Overall mortality was 33%. ECR-BSI is an emerging and increasingly common entity with a high mortality. This finding should be taken into account when selecting empirical treatment for presumptive CR-BSI.

Central venous catheter colonization with Staphylococcus aureus is not always an indication for antimicrobial therapy.

Whether patients whose catheter tip grows Staphylococcus aureus but who have no concomitant bacteraemia should receive antimicrobials remains an unresolved issue. However, a proportion of patients with catheter tips colonized by S. aureus have no blood cultures taken because of low suspicion of sepsis and the meaning of this microbiological finding is unknown. We have analysed all catheter tips growing S. aureus during a 6-year period and have selected patients without blood cultures taken 7 days before or after central vascular catheter removal. Patient's evolution was classified into good and poor outcome. Poor outcome was defined as S. aureus infection within 3 months after catheter withdrawal or death in the same period with no obvious cause. Patients with good and poor outcomes were compared to assess whether antimicrobial therapy influenced evolution. Sixty-seven patients fulfilled our inclusion criteria and five (7.4%) had a poor outcome. The administration of early anti-staphylococcal therapy had no impact on the outcome of this population (p 0.99). The only factor independently associated with a poor outcome was the presence of clinical signs of sepsis when the catheter was removed (OR 20.8; 95% CI 2.0-206.1; p 0.009). Our data suggest that patients with central vascular catheter tips colonized with S. aureus should be closely monitored for signs and symptoms of ongoing infection, but if these are not present then antimicrobial therapy does not seem justified.

Differential time to positivity (DTTP) for the diagnosis of catheter-related bloodstream infection: do we need to obtain one or more peripheral vein blood cultures?

The ideal number of blood samples to be obtained from peripheral veins (PVs) when differential time to positivity (DTTP) is being performed is an unresolved issue and most institutions obtain a single set. Our objective was to assess the number of proven central line-associated bloodstream infection (CLABSI) episodes that would have been recovered if blood had been cultured from one or two PVs. We performed a retrospective study in patients with proven CLABSI in which catheter lumens and two or more PV blood cultures were taken simultaneously. We calculated the number of episodes that would have been recovered if the culture of one or more PV blood cultures had been artificially eliminated. During a period of 4 years, we collected 60 episodes of proven CLABSI. Overall, if one PV culture had been eliminated in patients with two or three PV blood cultures, we would have documented 91.8% (p=0.362) and 96.9% (p>0.999) of episodes, respectively. If we had eliminated two PV blood cultures in patients with three PV blood cultures, 90.8% (p>0.999) of episodes would have been documented. When performing the DTTP technique to confirm CLABSI, a single paired PV blood culture was not associated with a significant number of missed CLABSI episodes.

Candida tropicalis fungaemia: incidence, risk factors and mortality in a general hospital.

The risk factors and clinical features of patients with Candida tropicalis fungaemia have not been fully defined. We performed a case-control study comparing 59 cases of C. tropicalis fungaemia with 177 episodes of fungaemia caused by other species of Candida in our hospital over a 24-year period (January 1985 to December 2008). Patients with C. tropicalis fungaemia were more likely to be older (median age, 67 vs. 56 years; p 0.01), to have cancer (45.5% vs. 31.6%, p 0.04), and to have the abdomen as the portal of entry (32.2% vs. 11.9%, p 0.001), and had a higher in-hospital mortality rate (61% vs. 44%, p 0.03). Multivariate analysis showed that the independent risk factors for C. tropicalis fungaemia were cancer (OR 4.5; 95% CI 1.05-3.83; p 0.03) and the abdomen as the portal of entry (OR 13.6; 95% CI 1.9-8.2; p <0.001). When survivors were compared with non-survivors, the risk factors associated with a poor outcome were neutropenia (19.4% vs. 0; p 0.03), corticosteroid treatment (36% vs. 13%; p 0.07), and septic shock (50% vs. 17.4%; p 0.01). The independent risk factors for mortality in the multivariate analysis were corticosteroid treatment (OR 8.2; 95% CI 0.9-27.7; p 0.04) and septic shock (OR 14.6; 95% CI 2.4-90.2; p 0.004), whereas urinary tract infection (OR 0.07; 95% CI 0.01-0.8; p 0.03) and catheter removal (OR 0.06; 95% CI 0.01-0.4; p 0.002) were protective factors. C. tropicalis is the fourth most common cause of fungaemia in our hospital. It is associated with underlying malignancy, the abdomen as the portal of entry, and poor outcome.

Tsukamurella: a cause of catheter-related bloodstream infections.

Tsukamurellae are strictly aerobic Gram-positive rods that can be easily misidentified as Corynebacterium species, Rhodococcus species, Nocardia species, Mycobacterium species, or other Gram-positive aerobic rods. They have been uncommonly reported as a cause of different human infections, including bloodstream infections. We describe 2 new cases of catheter-related bloodstream infections (CR-BSI) caused by Tsukamurella species and review 12 similar cases reported in the literature. Conventional procedures have often misidentified Tsukamurella species as other aerobic Gram-positive rods. This misidentification could be avoided using genotyping. All cases ultimately required the withdrawal of the infected line. The literature provides no firm conclusions regarding ideal choice or duration of antimicrobial therapy for this infection. Tsukamurella species should be added to the list of agents able to produce CR-BSI. Genotypic methods such as PCR 16S rRNA can allow a reliable identification at the genus level of Tsukamurella strains faster than a combination of conventional phenotypic methods.

Nasal carriage of S. aureus increases the risk of surgical site infection after major heart surgery.

Staphylococcus aureus is the main cause of surgical site infection (SSI) after major heart surgery (MHS), with the patient's endogenous flora as the principal source. However, the influence of nasal carriage of S. aureus on the development of SSI after MHS has not been established and Centers for Disease Control and Prevention guidelines do not make a recommendation for or against decolonisation. We performed a one-year observational study in which patients undergoing MHS were screened for nasal carriage of S. aureus before surgery. Cases of SSI were recorded and the risk factors of patients with and without SSI were analysed. During the study period, 357 patients were included in the protocol. Ninety-six patients (27%) were found to be nasal carriers of S. aureus and nine (9.4%) of these had meticillin-resistant (MRSA) strains. The overall incidence of SSI was 6.4%, with 4.2% for mediastinitis and 2.2% for superficial SSI. Nasal carriers of S. aureus had a significantly higher incidence of SSI than non-carriers (12.5% vs 5%, P=0.01). Among MRSA carriers, the incidence of SSI reached 33% (P<0.001). S. aureus was responsible for 64% of SSIs. Multivariate analysis showed that the independent factors for SSI were S. aureus nasal carriage [relative risk (RR): 3.1; 95% confidence interval (CI): 1.4-7.3; P=0.009], reoperation (RR: 3.1; 95% CI: 1.8-19.2; P=0.04) and diabetes mellitus (RR: 5.9; 95% CI: 1.8-19.2; P=0.003). Nasal carriage of S. aureus significantly increases the rate of nosocomial SSI after MHS and decolonisation strategies should be implemented in this population.

Linezolid therapy for infective endocarditis.

Linezolid is not yet recognised as a standard therapy for infective endocarditis. This report describes nine patients with endocarditis treated with linezolid and 33 similar cases from the medical literature. The majority of cases involved multiresistant strains, and the reasons for administering linezolid were refractory disease (60%), intolerance (28%), sequential therapy (12%) and a resistant pathogen (1%). Linezolid was administered for a mean of 37 days, with a successful outcome in 79% of cases. Reversible adverse effects were described in ten cases. The mean follow-up period was 8.5 months. Further data from randomised controlled clinical trials are needed to determine the efficacy and safety of linezolid for treating endocarditis.

Nosocomial bloodstream infections caused by Streptococcus pneumoniae.

A retrospective study of Streptococcus pneumoniae bacteraemia among adult patients in two large teaching hospitals in Spain identified 108 (10.6%) of 1,020 episodes as nosocomial pneumococcal bloodstream infections (NPBIs). Seventy-seven clinical records with sufficient data were available for analysis. The interval between admission and a positive blood culture was 3--135 days (median 17 days; interquartile range 8--27). The main underlying and predisposing conditions for NPBI were malignancy (31%), chronic obstructive pulmonary disease (28.6%), heart failure (16.9%), chronic renal failure (15.6%), liver cirrhosis (13%) and infection with human immunodeficiency virus (13%). Overall, 31.2% of patients developed severe sepsis, 11.7% septic shock, and 3.9% multi-organ failure. The main portals of entry were pneumonia (70.1%), meningitis (5.2%) and primary peritonitis (5.2%). Of the responsible serogroups, 78% were included in the 23-valent polysaccharide vaccine. Thirty-five (45.5%) patients died, with death considered to be related to the NPBI in 21 (27.3%) cases. Following multivariate analysis, factors that independently predicted death after adjusting for age were: ultimately fatal underlying disease (OR, 8.9; 95% CI, 0.8--94.3; p<0.001); rapidly fatal underlying disease (OR, 15.0; 95% CI, 2.8--81.3; p<0.001); heart failure (OR, 8.11; 95% CI, 1.1--60.8; p<0.03); inadequate empirical therapy (OR, 10.6; 95% CI, 1.2--97; p<0.003); a severe sepsis score (OR, 9.5; 95% CI, 1.9--47.0; p<0.001); and septic shock or multi-organ failure (OR, 63.7; 95% CI, 4.9--820.7; p<0.001). Adequate empirical therapy was an independent protective factor (OR, 0.05; 95% CI, 0.04--0.58; p<0.005), but the use of more than one antimicrobial agent was not.

An improved protocol for pulsed-field gel electrophoresis typing of Clostridium difficile.

Pulsed-field gel electrophoresis (PFGE) is the 'gold standard' technique for bacterial typing and has proved to be discriminatory and reproducible for typing Clostridium difficile. Nevertheless, a high proportion of strains are non-typable by this technique due to the degradation of the DNA during the process. The introduction of several modifications in the PFGE standard procedure increased typability from 40% (90 isolates) to 100% (220 isolates) while maintaining the high degree of discrimination and reproducibility of the technique.

Toxigenic status of Clostridium difficile in a large Spanish teaching hospital.

The aim of this study was to evaluate the toxigenic status of circulating strains of Clostridium difficile in a large teaching hospital. Overall 220 isolates were studied of which 199 (90.5 %) produced both large clostridial toxins detected by conventional methods. Ten more strains (4.5 %) had toxin A and B genes detectable by PCR. Eleven (5.0 %) variant strains (A- B+) were detected among the isolates studied and 10 strains (4.5 %) had the binary toxin genes (cdtA and cdtB).