Differential time to positivity and quantitative cultures for noninvasive diagnosis of catheter-related blood stream infection in children

Utility of Differential Time to Positivity in Diagnosing Central Line-Associated Bloodstream Infections: A Systematic Review and Meta-Analysis

BACKGROUND

Differential time to positivity (DTP), defined as pathogen growth at least 2 hours earlier from catheter versus paired peripheral blood cultures, is sometimes used to diagnose central line-associated bloodstream infections (CLABSIs). Previous studies assessing DTP, however, have been small, provided conflicting results, and did not assess heterogeneity across important subgroups.

METHODS

We systematically reviewed the diagnostic characteristics of DTP for CLABSI using MEDLINE, Embase, WoS, CINAHL, LILACS, AMED, and the Cochrane database. Studies were included if they reported sensitivities, specificities, predictive values, likelihood ratios, or 2 × 2 tables of DTP for diagnosing CLABSI. Extracted data were analyzed by using forest plots, bivariate model meta-analysis, and QUADAS-2 quality assessment.

RESULTS

We identified 274 records, of which 23 met the criteria for meta-analysis. Among 2526 suspected CLABSIs, DTP demonstrated a summary sensitivity of 81.3% (95% confidence interval [CI]: 72.8%-87.7%), specificity of 91.8% (95% CI: 84.5%-95.8%), positive likelihood ratio of 9.89 (95% CI: 5.14-19.00), and negative likelihood ratio of 0.20 (95% CI: .14-.30). Covariate analysis based on catheter duration, study design, and patient immune status demonstrated no significant differences. However, DTP performed worse for Staphylococcus aureus (low sensitivity but high specificity) and Candida (high sensitivity but low specificity) compared to other organisms.

CONCLUSIONS

DTP performs well in ruling CLABSIs in or out. Obtaining paired catheter and peripheral blood cultures for DTP when the infectious source is unclear may prevent unnecessary line removal and diagnostic tests. However, this must be balanced against higher contamination rates from catheter cultures.

The Applicability of a 2-Transcript Signature to Identify Bacterial Infections in Children with Febrile Neutropenia

Febrile neutropenia is a common complication during chemotherapy in paediatric cancer care. In this setting, clinical features and current diagnostic tests do not reliably distinguish between bacterial and viral infections. Children with cancer (n = 63) presenting with fever and neutropenia were recruited for extensive microbiological and blood RNA sampling. RNA sequencing was successful in 43 cases of febrile neutropenia. These were classified as having probable bacterial infection (n = 17), probable viral infection (n = 13) and fever of unknown origin (n = 13) based on microbiological defined infections and CRP cut-off levels. RNA expression data with focus on the 2-transcript signature (FAM89A and IFI44L), earlier shown to identify bacterial infections with high specificity and sensitivity, was implemented as a disease risk score. The median disease risk score was higher in the probable bacterial infection group, -0.695 (max 2.795; min -5.478) compared to the probable viral infection group -3.327 (max 0.218; min -7.861), which in ROC analysis corresponded to a sensitivity of 0.88 and specificity of 0.54 with an AUC of 0.80. To further characterise the immune signature, analysis of significantly expressed genes and pathways was performed and upregulation of genes associated to antibacterial responses was present in the group classified as probable bacterial infection. Our results suggest that the 2-transcript signature may have a potential use as a diagnostic tool to identify bacterial infections in immunosuppressed children with febrile neutropenia.

High positive predictive value of Gram stain on catheter-drawn blood samples for the diagnosis of catheter-related bloodstream infection in intensive care neonates

Catheter-related bloodstream infections (CRBSIs) remain a leading cause of healthcare-associated infections in preterm infants. Rapid and accurate methods for the diagnosis of CRBSIs are needed in order to implement timely and appropriate treatment. A retrospective study was conducted during a 7-year period (2005-2012) in the neonatal intensive care unit of the University Hospital Erasme to assess the value of Gram stain on catheter-drawn blood samples (CDBS) to predict CRBSIs. Both peripheral samples and CDBS were obtained from neonates with clinically suspected CRBSI. Gram stain, automated culture and quantitative cultures on blood agar plates were performed for each sample. The paired quantitative blood culture was used as the standard to define CRBSI. Out of 397 episodes of suspected CRBSIs, 35 were confirmed by a positive ratio of quantitative culture (>5) or a colony count of CDBS culture >100 colony-forming units (CFU)/mL. All but two of the 30 patients who had a CDBS with a positive Gram stain were confirmed as having a CRBSI. Seven patients who had a CDBS with a negative Gram stain were diagnosed as CRBSI. The sensitivity, specificity, positive predictive value and negative predictive value of Gram stain on CDBS were 80, 99.4, 93.3 and 98.1 %, respectively. Gram staining on CDBS is a viable method for rapidly (<1 h) detecting CRBSI without catheter withdrawal.

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.

[Central venous-catheter related bacteremia: incidence and risk factors in a hospital in western México]

BACKGROUND

Central venous catheters (CVC) are needed for monitoring and treatment of critically ill patients; however, their use increases the risk of bacteremia. The aim of the study was to quantify the incidence of central venous catheter-related bacteremia (CVCRB) and to identify factors associated with this infection.

METHODS

A prospective cohort study was conducted in a concentration hospital of western Mexico. The association of CVCRB and study variables was investigated using multivariate Cox regression analysis.

RESULTS

Two hundred four patients with CVC were studied. The average age was 4.6 years; 66.2% were male. Insertion sites of the catheters were subclavian vein 72.5% (n = 148), jugular vein 20.1% (n = 41) and femoral vein 7.4% (n = 15). CVCRB incidence was 6.5 events/1,000 catheter days; microorganisms identified were gram-positive cocci 37.5% (n = 6), gram-negative bacilli 37.5% (n = 6) and Candida albicans 25% (n = 4). It was observed that the increase in catheter manipulations per day was associated with bacteremia (HR 1.14, 95% CI 1.06 - 1.23), whereas the use of intravenous antibiotics showed a protective effect (HR 0.84, 95% CI 0.76-0.92).

CONCLUSIONS

In addition to strategies of maximum caution when placing or manipulating the catheter, we recommend decreasing, as much as possible, disconnects between the CVC and infusion line. Antibiotics showed a protective effect, but the outcome is uncertain and promotion of antimicrobial resistance should be considered.

[Blood cultures in the paediatric emergency department. Guidelines and recommendations on their indications, collection, processing and interpretation]

Blood culture (BC) is the gold standard when a bacteraemia is suspected, and is one of the most requested microbiological tests in paediatrics. Some changes have occurred in recent years: the introduction of new vaccines, the increasing number of patients with central vascular catheters, as well as the introduction of continuous monitoring BC systems. These changes have led to the review and update of different factors related to this technique in order to optimise its use. A practice guideline is presented with recommendations on BC, established by the Spanish Society of Paediatric Emergency Care and the Spanish Society for Paediatric Infectious Diseases. After reviewing the available scientific evidence, several recommendations for each of the following aspects are presented: BC indications in the Emergency Department, how to obtain, transport and process cultures, special situations (indications and interpretation of results in immunosuppressed patients and/or central vascular catheter carriers, indications for anaerobic BC), differentiation between bacteraemia and contamination when a BC shows bacterial growth and actions to take with a positive BC in patients with fever of unknown origin.

Strategies for catheter-related blood stream infection based on medical course in children receiving parenteral nutrition

PURPOSE

The central venous catheter (CVC) is a useful device for patients requiring parenteral nutrition (PN). However, the risk for catheter-related blood stream infection (CRBSI) is always present. We analyzed the medical course pattern and considered the strategies against febrile events in patients with CVC.

METHODS

Nine patients receiving PN in our institute from January 2009 to December 2010 were reviewed. Statistical analysis was performed with the Mann-Whitney U test. A p value of <0.05 was considered statistically significant.

RESULTS

Eighty-four febrile events were observed. Fifty-six specimens had a positive blood culture, and 52 (93%) specimens were found to be positive in 48 h. The fever dissolved within 48 h in 76 (90%) events after our scheduled treatment. Between the positive and negative blood culture groups, no statistical difference was observed in the count of white blood cell (p = 0.15), the proportion of neutrophils (p = 0.11) and C-reactive protein (p = 0.64). None of the CVCs were removed because of failure to control infection.

CONCLUSION

We recommend the treatment for CRBSI be initiated when patients with CVC develop a high-grade fever, even before exact identification of the cause of infection. The treatment can be corrected after the re-evaluation at 48 h.