Diagnosis of catheter-related bloodstream infection in neonates: a study on the value of differential time to positivity of paired blood cultures

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.

Blood culture collection practices in NICU; A national survey

Background

Sepsis is the leading cause of mortality and morbidity in neonates. Blood cultures are the gold standard in diagnosing neonatal sepsis; however, there are currently no consensus guidelines for blood culture collection in neonates and significant practice variation exists in Neonatal Intensive Care Units (NICUs) globally.

Objective

To examine current practices in obtaining blood cultures in the evaluation of neonatal sepsis in NICUs across Canada.

Methods

A nine-item electronic survey was sent to each of the 29 level-3 NICUs in Canada, which are equipped to provide highly specialized care for newborns.

Results

Responses were received from 90% (26/29) of sites. Sixty-five percent (17/26) of sites have blood culture collection guidelines for the investigation of neonatal sepsis. Forty-eight percent (12/25) of sites routinely target 1.0 mL per culture bottle. In late-onset sepsis (LOS), 58% (15/26) of sites process one aerobic culture bottle, whereas four sites routinely add anaerobic culture bottles. In early-onset sepsis (EOS) in very low birth weight infants (BW <1.5 kg), 73% (19/26) of sites use umbilical cord blood, and 72% (18/25) use peripheral venipuncture. Two sites routinely collect cord blood for culture in EOS. Only one site applies the concept of differential time-to-positivity to diagnose central-line-associated bloodstream infection.

Conclusions

There is significant practice variation in methods used to obtain blood cultures in level-3 NICUs across Canada. Standardization of blood culture collection practices can provide reliable estimates of the true incidence of neonatal sepsis and help to develop appropriate antimicrobial stewardship strategies.

Dual-site blood culture yield and time to positivity in neonatal late-onset sepsis

OBJECTIVE

To determine whether culture yield and time to positivity (TTP) differ between peripheral and central vascular catheter-derived blood cultures (BCx) in neonatal intensive care unit (NICU) patients evaluated for late-onset sepsis.

DESIGN

Single-centre, retrospective, observational study.

SETTING

Level IV NICU.

PARTICIPANTS

The study included infants >72 hours old admitted to NICU in 2007-2019 with culture-confirmed bacteraemia. All episodes had simultaneous BCx drawn from a peripheral site and a vascular catheter ('catheter culture').

MAIN OUTCOME MEASURES

Dual-site culture yield and TTP.

RESULTS

Among 179 episodes of late-onset bacteraemia (among 167 infants) with concurrently drawn peripheral and catheter BCx, the majority (67%, 120 of 179) were positive from both sites, compared with 17% (30 of 179) with positive catheter cultures only and 16% (29 of 179) with positive peripheral cultures only. 66% (19 of 29) of episodes with only positive peripheral BCx grew coagulase-negative Staphylococcus, while 34% (10 of 29) were recognised bacterial pathogens. Among 120 episodes with both peripheral and catheter BCx growth, catheter cultures demonstrated bacterial growth prior to paired peripheral cultures in 78% of episodes (93 of 120, p<0.001). The median TTP was significantly shorter in catheter compared with peripheral cultures (15.0 hours vs 16.8 hours, p<0.001). The median elapsed time between paired catheter and peripheral culture growth was 1.3 hours.

CONCLUSION

Concurrently drawn peripheral and catheter BCx had similar yield. While a majority of episodes demonstrated dual-site BCx growth, a small but important minority of episodes grew virulent pathogens from either culture site alone. While dual-site culture practices may be useful, clinicians should balance the gain in sensitivity of bacteraemia detection against additive contamination risk.

Efficacy of Antimicrobial-Impregnated Catheters for Prevention of Bloodstream Infections in Pediatric Patients: A Meta-Analysis

Background: Multiple Randomized controlled trials (RCTs) have evaluated the efficacy of antimicrobial-impregnated catheters to prevent catheter-related bloodstream infections (CRBSI). However, the RCTs showed contradictory results, the studies were limited in sample size and methodology quality. Thus, we conducted a meta-analysis to overcome these RCT limitations. Methods: We designed a meta-analysis of RCTs comparing antimicrobial-impregnated and conventional catheters for the prevention of CRBSI. We conducted a detailed search of various databases for RCTs published before November 2019. We calculated mean differences (MDs) and pooled odds ratios (ORs) with 95% confidence intervals (CIs) using a random-effects model. Results: We included five RCTs with a total of 2,294 patients. The incidence of CRBSI between the two groups was 0.50 (95% CI, 0.19-1.27), with evidence of heterogeneity (I ² = 55%). The difference was not statistically significant (p = 0.15). On subgroup analysis based on the age of the sample, there was no difference in the rate of CRBSI in the neonatal population [0.42 (95% CI, 0.08-2.27 I ² = 61% p = 0.31] as well as pediatric population [0.45 (95% CI, 0.12-1.67 I ² = 39% p = 0.23]. The summary OR on the incidence of catheter colonization between antimicrobial-impregnated and conventional catheters was 0.64 (95% CI, 0.17-2.35), with no evidence of heterogeneity (I ² = 0%) and a non-significant difference (p = 0.50). Conclusions: To conclude, analysis of a limited number of heterogeneous studies mostly with a small sample indicates that the CRBSI and catheter colonization rates are similar between conventional and antimicrobial-impregnated catheters in the pediatric and neonatal population. There is an urgent need for large-scale RCTs focusing on different antimicrobial-impregnated catheters in these patients to further enhance current evidence.

Excluding Clinically Significant Bacteremia by 24 Hours in Otherwise Well Febrile Children Younger Than 16 Years: A Study of More Than 50,000 Blood Cultures

BACKGROUND

In febrile children given empiric parenteral antibiotics, guidelines advise provisional reporting of negative blood cultures and antibiotic review after 36 hours incubation for neonates and 48 hours for older children. Following improvements in culture processing and childhood vaccination, we revisited this important clinical topic, assessing time to exclude clinically significant bacteremia in well-appearing febrile children with no comorbidities or features of sepsis.

METHODS

We analyzed the results of all 53,276 pediatric blood cultures taken during an 8-year period at a UK hospital.

RESULTS

1308 (2.5%) cultures were positive, of which 333 (25.5%) grew pathogens typically associated with clinically significant bacteremia. The remaining 975 (74.5%) grew organisms associated with contaminated culture, or with opportunistic infection only in children with relevant risk factors. Time to positivity (TTP) from incubation was significantly shorter for the 333 definite pathogens than the 975 contaminating/opportunistic organisms, with 92% of definite pathogens identified by 24 hours incubation. Only 3 of all definite pathogens were identified after 24 hours in children otherwise eligible for discharge at 24 hours. There was no significant difference in TTP for definite pathogens between neonates and older children. Median time from specimen collection to incubation was 3 hours.

CONCLUSIONS

Clinically significant bacteremia can be excluded by 24 hours incubation in well-appearing febrile children with no comorbidities or features of sepsis. This is the largest dataset of its kind, and the second to compare neonates and older children. Our findings may inform future guidelines, facilitating earlier antibiotic review and discharge.

Risk Factors for Central Line-Associated Bloodstream Infection in Critically Ill Neonates

OBJECTIVE

To identify independent risk factors to develop a central line- associated bloodstream infection (CLABSI) in critically ill neonates with major underlying diseases.

METHODS

A nested case-control study was conducted in a neonatal intensive care unit (NICU). Patients with a central venous catheter (CVC) were included. Cases were neonates who developed a CLABSI and controls were patients without CLABSI. Variables included: perinatal history, characteristics of the catheter, installation and catheter use, surgical interventions, and hospital stay. Odds ratio (OR) and 95% confidence intervals (CI) were calculated. X², Fisher exact, and Mann-Whitney U tests were used when appropriate. Variables with a p value ≤0.10 in the univariate analysis were introduced in a non-conditional logistic regression model.

RESULTS

Seventy four cases and 105 controls were analyzed. Univariate risk factors were: any surgery, abdominal surgery, length of hospitalization (≥14 d), double-lumen CVC, surgical cut-down technique, complications, CVC placement in internal jugular vein, dressing type, blood transfusions, parenteral nutrition, and number of CVC manipulations (>200). In the logistic regression analysis, independent risk factors with a p value <0.05 were: double-lumen catheter (OR 5.8, 95% CI 1.2-30), length of hospitalization ≥14 d (OR 4.6, 95% CI 1.8-11.4), abdominal surgery (OR 2.7, 95% CI 1.2-6.2) and blood transfusions (OR 2.5, 95% CI 1.2-5.3).

CONCLUSIONS

One risk factor was related to the catheter itself. Management of underlying diseases in specialized NICU contributes to a greater extent to the development of a central line-associated bloodstream infection.

Clinical usefulness of catheter-drawn blood samples and catheter tip cultures for the diagnosis of catheter-related bloodstream infections in neonatology: A systematic review

OBJECTIVES

Neonatal sepsis is the most frequent health care-associated infection in neonatal units. This study aimed to analyze articles on the clinical usefulness of catheter-drawn blood samples and catheter tip cultures for the diagnosis of intravascular catheter-related bloodstream infection (CRBSI) in neonates.

METHODS

A systematic search was performed for studies published from 1987-2017, without language restriction. Observational studies carried out in neonates with CRBSI diagnosed using catheter-drawn blood samples or catheter tip cultures were included.

RESULTS

A total of 412 articles were identified in the databases and 10 articles were included. The 7 studies that evaluated central venous catheter tip cultures and cultures of catheter fragments presented sensitivities ranging from 58.5%-100% and specificities ranging from 60%-95.7%. Three studies that evaluated catheter-drawn blood cultures, paired with peripheral blood cultures, reported sensitivity and specificity of 94% and 71% when evaluated for the differential time to positivity. When quantitative evaluation was performed, the sensitivity and specificity were 80% and 99.4%.

CONCLUSIONS

Most of the studies analyzed cultures from the central venous catheter tip and catheter fragments for the diagnosis of CRBSI in neonatal populations. The results of this review suggest that the analysis of the catheter-drawn blood samples and catheter tip cultures, paired with peripheral blood cultures, are efficient methods for the diagnosis of CRBSI in neonates.

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.

Catheter-related and infusion-related sepsis

This article focuses on the pathogenesis, diagnosis, prevention, and management of infectious complications of intravascular cannulation and fluid infusion. Although continuous vascular access is one of the most essential modalities in modern-day medicine, there is a substantial and underappreciated potential for producing iatrogenic complications, the most important of which is blood-borne infection. Clinicians often fail to consider the diagnosis of infusion-related sepsis because clinical signs and symptoms are indistinguishable from bloodstream infections arising from other sites. Understanding and consideration of the risk factors predisposing patients to infusion-related infections may guide the development and implementation of control measures for prevention.

Reduction of catheter-related bloodstream infections in preterm infants by the use of catheters with the AgION antimicrobial system

OBJECTIVE

The present study aims to assess if use of a silver zeolite-impregnated umbilical catheter (AgION technology) can decrease the occurrence of catheter-related bloodstream infection (CRBSIs) in preterm infants.

STUDY DESIGN

Infants with gestational age<30weeks were randomized to receive an AgION impregnated or non-impregnated polyurethane umbilical venous catheter (UVC). The primary endpoint was the incidence of CRBSIs during the time the UVC was in place.

RESULTS

We studied 86 infants, 41 of whom received the AgION catheter and 45 the non-impregnated catheter. During umbilical venous catheterization 2% of infants in the AgION group developed CRBSI in comparison with 22% of infants in the control group (p=0.005). AgION catheters were well tolerated and none of the patients showed signs attributable to silver toxicity.

CONCLUSIONS

The AgION-impregnated UVCs were effective in decreasing the development of CRBSIs in preterm infants compared to non-impregnated polyurethane UVCs.

Central line "attention" is their best prevention

Central line associated blood stream infections (CLABIs) are associated with an increase in length of stay, morbidity, hospital costs, and mortality. In 2009, CLABIs were on the increase at Covenant Healthcare's 55 bed Level III neonatal intensive care unit (NICU). Prior to this practice initiative, there were no standardized central line management practices in the NICU. We retrospectively reviewed the incidence CLABIs for the six months prior to the initiation of the standardization of central line management and then 3 months following the implementation of the new practice policy. Specific outcomes measured were the number of CLABIs, length of stay related to CLABIs, and adherence to the policies and procedures. The project was implemented in four phases: 1) hand hygiene, 2) "scrub the hub", 3) central line tubing changes, 4) central line insertion, removal, and dressing changes. Although there were no statistically significant changes in the outcome measures, there were clinically significant differences between length of stay and risk for central line infection, incidence of CLABIs, and an increase in adherence to the central line practice change policies. The study showed for every week that is added to the patient stay, the patient was 7 times more likely to have a CLABIs. The rate of central line infection was decreased from 15.6 percent per 1000 line days to zero in 2010.

A seven-year survey of management of coagulase-negative staphylococcal sepsis in the neonatal intensive care unit: vancomycin may not be necessary as empiric therapy

BACKGROUND

The typical empiric therapy for coagulase-negative staphylococcal (CONS) sepsis includes vancomycin. In our neonatal intensive care unit, we have consistently avoided the use of vancomycin to treat CONS sepsis, except for specific cases, and have used instead cefazolin as empiric agent.

OBJECTIVES

The clinical outcome of infants with CONS sepsis was evaluated in relation to the susceptibility of CONS blood isolates to cefazolin over a period of 7 years.

METHODS

Clinical characteristics, symptoms of sepsis and antibiotic use were studied retrospectively. Susceptibility of CONS blood isolates to cefazolin was determined by E-test.

RESULTS

Of 163 infants with proven CONS sepsis, 121/140 (86%) infants with a cefazolin-susceptible (minimum inhibition concentration (MIC) ≤8 mg/l) and 21/23 (91%) with a cefazolin-resistant (MIC ≥32 mg/l) blood isolate were treated with cefazolin. 21 (13%) infants were switched to vancomycin, in only 3 of them CONS had become resistant to cefazolin. The majority (81%) of the infants with a good response to cefazolin had the indwelling central venous catheter removed, in contrast to only 22% of the infants with cefazolin treatment failure. Median cefazolin MIC values were 0.75-2 mg/l during the study period.

CONCLUSIONS

The great majority of infants with CONS sepsis was successfully treated with cefazolin. The use of vancomycin could be restricted to specific cases. Despite the consistent use of cefazolin in neonatal CONS sepsis over an extended period of time, cefazolin MIC values remained low and in the susceptible range. Removal of the central venous catheter in infants with clinical symptoms of sepsis is an important therapeutic measure.

Time to positivity of neonatal blood cultures: fast and furious?

The aim of this study was to determine the time to positivity (TTP) of neonatal blood cultures, to investigate differences between early onset versus late-onset sepsis, and non-proven versus proven sepsis, and to examine differences in TTP by organism type using a retrospective observational study at the Neonatal Intensive Care Unit, Antwerp University Hospital, Belgium. The subjects were 1828 neonates with suspected sepsis who were treated with antimicrobials for at least 3 days. The TTP was recorded for all episodes of suspected sepsis in an approximately 6.5 year period. A total of 2916 blood cultures were collected, of which 437 (15%) became positive. The overall TTP was 21.33 h (Q1-Q3 13.17-32.46). The difference between the median TTP in early onset versus late-onset sepsis was 0.83 h (22.00 versus 21.17 h, P=0.75). The median TTP for Gram-negative organisms was 11.17 h (Q1-Q3 8.84-15.67), whereas the median TTP for Gram-positive organisms was 23.59 h (Q1-Q3 15.29-34.58, P<0.001). In Gram-positive isolates, the median TTP for coagulase-negative staphylococci (CNS) was 26.67 h (Q1-Q3 19.00-38.17), whereas the median TTP for non-CNS was 12.83 h (Q1-Q3 10.50-18.17, P<0.001). The median TTP in proven sepsis was 20.17 h (Q1-Q3 13.00-30.37), whereas it was 29.67 h (Q1-Q3 21.17-50.63, P<0.001) in non-proven sepsis. TTP of neonatal blood cultures was significantly shorter for Gram-negative organisms. We suggest shortening the total incubation time of neonatal blood cultures to a maximum of 3 days. However, blood cultures collected in infants<72 h of age might require a longer incubation time. According to our results, it may be safe to narrow the antimicrobial spectrum to solely target Gram-positive bacteria when the culture is still negative after 48 h, and to cease antimicrobial therapy when the culture is still negative after 72 h in clinically well infants.

A Retrospective Study to Determine Whether accessing Frequency Affects the Incidence of Microbial Colonisation in Peripheral Arterial Catheters

Peripheral arterial catheters are used for the continuous monitoring of blood pressure and repeated blood sampling in critically ill patients, but can be a source of catheter-related bloodstream infection. A common assumption is that the more frequently an arterial catheter is accessed, the greater the likelihood of contamination and colonisation to occur. We sought to determine whether the accessing frequency has an influence on the rate of colonisation in a peripheral arterial catheter.

A retrospective, unmatched, nested case control study was conducted in our intensive care unit. The intensive care unit charts of 96 arterial catheters from 83 patients were examined to measure the number of times each respective arterial catheter was accessed. Multivariate Cox proportional hazards regression was used to compare the rate of accessing of arterial catheters and account for varying arterial catheter in situ duration. Arterial catheters which had a high access rate of 8.1 or more times/day (five colonised of 32 patients: hazards ratio 1.69, 95% confidence interval 0.52 to 5.49; P=0.77), or a medium access rate of 6.7 to 8.0 times/day (six colonised of 32 patients: hazards ratio, 1.35, 95% confidence interval, 0.37 to 4.92: P=0.65) were not significantly more colonised when compared to arterial catheters which had a low access rate of 0 to 6.6 times/day (six colonised of 32 patients), adjusted for arterial catheter insertion site and place in hospital where the arterial catheter insertion was performed.

We were unable to demonstrate that the accessing frequency of an arterial catheter was a major predisposing factor for the likelihood of colonisation. Other mechanisms other than hub colonisation should be investigated further.