Point-of-care testing for procalcitonin in identifying bacterial infections in young infants: a diagnostic accuracy study

Diagnostic test accuracy of procalcitonin and C-reactive protein for predicting invasive and serious bacterial infections in young febrile infants: a systematic review and meta-analysis

BACKGROUND

Febrile infants presenting in the first 90 days of life are at higher risk of invasive and serious bacterial infections than older children. Modern clinical practice guidelines, mostly using procalcitonin as a diagnostic biomarker, can identify infants who are at low risk and therefore suitable for tailored management. C-reactive protein, by comparison, is widely available, but whether C-reactive protein and procalcitonin have similar diagnostic accuracy is unclear. We aimed to compare the test accuracy of procalcitonin and C-reactive protein in the prediction of invasive or serious bacterial infections in febrile infants.

METHODS

For this systematic review and meta-analysis, we searched MEDLINE, EMBASE, Web of Science, and The Cochrane Library for diagnostic test accuracy studies up to June 19, 2023, using MeSH terms "procalcitonin", and "bacterial infection" or "fever" and keywords "invasive bacterial infection*" and "serious bacterial infection*", without language or date restrictions. Studies were selected by independent authors against eligibility criteria. Eligible studies included participants aged 90 days or younger presenting to hospital with a fever (≥38°C) or history of fever within the preceding 48 h. The primary index test was procalcitonin, and the secondary index test was C-reactive protein. Test kits had to be commercially available, and test samples had to be collected upon presentation to hospital. Invasive bacterial infection was defined as the presence of a bacterial pathogen in blood or cerebrospinal fluid, as detected by culture or quantitative PCR; authors' definitions of serious bacterial infection were used. Data were extracted from selected studies, and the detection of invasive or serious bacterial infections was analysed with two models for each biomarker. Diagnostic accuracy was determined against internationally recognised cutoff values (0·5 ng/mL for procalcitonin, 20 mg/L for C-reactive protein) and pooled to calculate partial area under the curve (pAUC) values for each biomarker. Optimum cutoff values were identified for each biomarker. This study is registered with PROSPERO, CRD42022293284.

FINDINGS

Of 734 studies derived from the literature search, 14 studies (n=7755) were included in the meta-analysis. For the detection of invasive bacterial infections, pAUC values were greater for procalcitonin (0·72, 95% CI 0·56-0·79) than C-reactive protein (0·28, 0·17-0·61; p=0·016). Optimal cutoffs for detecting invasive bacterial infections were 0·49 ng/mL for procalcitonin and 13·12 mg/L for C-reactive protein. For the detection of serious bacterial infections, procalcitonin and C-reactive protein had similar pAUC values (0·55, 0·44-0·69 vs 0·54, 0·40-0·61; p=0·92). For serious bacterial infections, the optimal cutoffs for procalcitonin and C-reactive protein were 0·17 ng/mL and 16·18 mg/L, respectively. Heterogeneity was low for studies investigating the test accuracy of procalcitonin in detecting invasive bacterial infection (I2=23·5%), high for studies investigating procalcitonin for serious bacterial infection (I2=75·5%), and moderate for studies investigating C-reactive protein for invasive bacterial infection (I2=49·5%) and serious bacterial infection (I2=28·3%). The absence of a single definition of serious bacterial infection across studies was the greatest source of interstudy variability and potential bias.

INTERPRETATION

Within a large cohort of febrile infants, a procalcitonin cutoff of 0·5 ng/mL had a superior pAUC value to a C-reactive protein cutoff of 20 mg/L for identifying invasive bacterial infections. In settings without access to procalcitonin, C-reactive protein should therefore be used cautiously for the identification of invasive bacterial infections, and a cutoff value below 20 mg/L should be considered. C-reactive protein and procalcitonin showed similar test accuracy for the identification of serious bacterial infection with internationally recognised cutoff values. This might reflect the challenges involved in confirming serious bacterial infection and the absence of a universally accepted definition of serious bacterial infection.

FUNDING

None.

Healthcare seeking outside healthcare facilities and antibiotic dispensing patterns in rural Burkina Faso: A mixed methods study

OBJECTIVE

Optimising antibiotic use is important to limit increasing antibiotic resistance. In rural Burkina Faso, over-the-counter dispensing of antibiotics in community pharmacies and non-licensed medicine retail outlets facilitates self-medication. We investigated its extent, reasons and dispensing patterns.

METHODS

In an exploratory mixed-method design conducted between October 2020 and December 2021, this study first explored illness perceptions, the range of healthcare providers in communities, antibiotics knowledge and reasons for seeking healthcare outside healthcare facilities. Second, frequencies of illness and healthcare utilisation in the last 3 months were quantitatively measured.

RESULTS

Participants distinguished between natural and magico-religious illnesses, according to origins. For illnesses considered to be 'natural', healthcare was mainly sought at healthcare facilities, private pharmacies and informal drug outlets. For illnesses considered as magico-religious, traditional healers were mainly visited. Antibiotics were perceived in the community as medicines similar to painkillers. Healthcare-seeking outside healthcare facilities was reported by 660/1973 (33.5%) participants reporting symptoms, including 315 (47.7%) to informal vendors. Healthcare seeking outside facilities was less common for 0-4-year-olds (58/534, 10.9% vs. 379/850, 44.1% for ≥5-year-olds) and decreased with improving socio-economic status (108/237, 45.6% in the lowest quintile; 96/418, 23.0% in the highest). Reported reasons included financial limitation, and also proximity to informal drug vendors, long waiting times at healthcare facilities, and health professionals' non-empathetic attitudes towards their patients.

CONCLUSION

This study highlights the need to facilitate and promote access to healthcare facilities through universal health insurance and patient-centred care including reducing patients' waiting time. Furthermore, community-level antibiotic stewardship programmes should include community pharmacies and informal vendors.

Diagnosis of bacterial infection in children with relapse of nephrotic syndrome: a personalized decision-analytic nomogram and decision curve analysis

BACKGROUND

Infections associated with nephrotic relapses (NR) are often managed according to physician preferences. A validated prediction tool will aid clinical decision-making and help in rationalizing antibiotic prescriptions. Our objective was to develop a biomarker-based prediction model and a regression nomogram for the prediction of the probability of infection in children with NR. We also aimed to perform a decision curve analysis (DCA).

METHODS

This cross-sectional study included children (1-18 years) with NR. The outcome of interest was the presence of bacterial infection as diagnosed using standard clinical definitions. Total leucocyte count (TLC), absolute neutrophil count (ANC), quantitative C-reactive protein (qCRP), and procalcitonin (PCT) were the biomarker predictors. Logistic regression was used to identify the best biomarker model, followed by discrimination and calibration testing. Subsequently, a probability nomogram was constructed and DCA was done to determine the clinical utility and net benefits.

RESULTS

We included 150 relapse episodes. A bacterial infection was diagnosed in 35%. Multivariate analysis showed the ANC + qCRP model to be the best predictive model. This model displayed excellent discrimination (AUC: 0.83), and calibration (optimism-adjusted intercept: 0.015, slope: 0.926). A prediction nomogram and web-application was developed. The superiority of the model was also confirmed by DCA in the probability threshold range of 15-60%.

CONCLUSIONS

An ANC-based and qCRP-based internally validated nomogram can be used for the prediction of probability of infection in non-critically ill children with NR. Decision curves from this study will aid in the decision-making of empirical antibiotic therapy, incorporating threshold probabilities as a surrogate of physician preference. A higher resolution version of the Graphical abstract is available as Supplementary information.

The evolving value of older biomarkers in the clinical diagnosis of pediatric sepsis

Sepsis remains the leading cause of childhood mortality worldwide. The evolving definition of pediatric sepsis is extrapolated from adult studies. Although lacking formal validation in the pediatric population, this working definition has historically proven its clinical utility. Prompt identification of pediatric sepsis is challenging as clinical picture is often variable. Timely intervention is crucial for optimal outcome, thus biomarkers are utilized to aid in immediate, yet judicious, diagnosis of sepsis. Over time, their use in sepsis has expanded with discovery of newer biomarkers that include genomic bio-signatures. Despite recent scientific advances, there is no biomarker that can accurately diagnose sepsis. Furthermore, older biomarkers are readily available in most institutions while newer biomarkers are not. Hence, the latter's clinical value in pediatric sepsis remains theoretical. Albeit promising, scarce data on newer biomarkers have been extracted from research settings making their clinical value unclear. As interest in newer biomarkers continue to proliferate despite their ambiguous clinical use, the literature on older biomarkers in clinical settings continue to diminish. Thus, revisiting the evolving value of these earliest biomarkers in optimizing pediatric sepsis diagnosis is warranted. This review focuses on the four most readily available biomarkers to bedside clinicians in diagnosing pediatric sepsis. IMPACT: The definition of pediatric sepsis remains an extrapolation from adult studies. Older biomarkers that include C-reactive protein, procalcitonin, ferritin, and lactate are the most readily available biomarkers in most pediatric institutions to aid in the diagnosis of pediatric sepsis. Older biomarkers, although in varying levels of reliability, remain to be useful clinical adjuncts in the diagnosis of pediatric sepsis if used in the appropriate clinical context. C-reactive protein and procalcitonin are more sensitive and specific among these older biomarkers in diagnosing pediatric sepsis although evidence varies in different age groups and clinical scenarios.

The utility of point of care testing of procalcitonin in paediatric acute assessment

OBJECTIVE

Febrile illnesses are a common cause of presentation in acute pediatrics, with biomarkers frequently used to help differentiate mild infections from serious bacterial infections (SBI). We aimed to see if a point of care test for procalcitonin could help to reduce antibiotic use and avoid unnecessary admission.

PATIENTS AND METHODS

A point of care procalcitonin machine which produces results within 20 minutes was introduced to two pediatric assessment units across both sites of a secondary-care hospital trust, alongside guidance for when tested would be appropriate. We performed a prospective, observational, pilot service evaluation, of all children tested during the study period of November 2018 to March 2019. We collected data at the time of testing, including the indication for testing and plan prior to testing, then retrospectively collected outcome data for children tested including diagnosis, treatment and whether the child was admitted to hospital.

RESULTS

68 tests were performed over 5 months. There are differing denominators due to missing data. Children were predominantly male (40/68, 58.8%) and pre-school age (median age 2.9y, Q1-Q3 1.3-6.7). Severity of illness was low, with 7/54 (11.5%) triggering sepsis tools. The primary indication for testing was febrile illness with no source of infection and some concerning features (31/59, 52.5%). Following testing, 35/67 (52.5%) of patients were admitted and 31/67 (47.1%) had IV antibiotics. A low procalcitonin (<0.5 ng/L) was observed in 46/67 (69.1%) of patients, however 21/46 (45.7%) of these children were admitted and 16/46 (34.8%) were given IV antibiotics. Procalcitonin performed poorly at detecting SBIs in this cohort (result >0.5 ng/L for 1/5 SBIs).

CONCLUSION

There was no clear impact of point of care procalcitonin on admission or antibiotic prescribing in this small pilot study. Clinicians often tested for reasons outside the recommended scenarios and often treated "low risk" patients, as determined by low procalcitonin, with antibiotics. These effects may be due to low familiarity with procalcitonin as a biomarker.

Rapid Quantum Magnetic IL-6 Point-of-Care Assay in Patients Hospitalized with COVID-19

Interleukin-6 (IL-6) has been linked to several life-threatening disease processes. Developing a point-of-care testing platform for the immediate and accurate detection of IL-6 concentrations could present a valuable tool for improving clinical management in patients with IL-6-mediated diseases. Drawing on an available biobank of samples from 35 patients hospitalized with COVID-19, a novel quantum-magnetic sensing platform is used to determine plasma IL-6 concentrations. A strong correlation was observed between IL-6 levels measured by QDTI10x and the Luminex assay (r = 0.70, p-value < 0.001) and between QDTI80x and Luminex (r = 0.82, p-value < 0.001). To validate the non-inferiority of QDTI to Luminex in terms of the accuracy of IL-6 measurement, two clinical parameters—the need for intensive care unit admission and the need for mechanical intubation—were chosen. IL-6 concentrations measured by the two assays were compared with respect to these clinical outcomes. Results demonstrated a comparative predictive performance between the two assays with a significant correlation coefficient. Conclusion: In short, the QDTI assay holds promise for implementation as a potential tool for rapid clinical decision in patients with IL-6-mediated diseases. It could also reduce healthcare costs and enable the development of future various biomolecule point-of-care tests for different clinical scenarios.

Umbilical Cord Procalcitonin to Detect Early-Onset Sepsis in Newborns: A Promising Biomarker

Background: Up to 7% of neonates born in high-income countries receive antibiotics for suspected early-onset sepsis (EOS). Culture-proven neonatal sepsis has a prevalence of 0.2%, suggesting considerable overtreatment. We studied the diagnostic accuracy of umbilical cord blood and infant blood procalcitonin (PCT) in diagnosing EOS to improve antibiotic stewardship. Methods: Umbilical cord blood PCT was tested in newborns ≥ 32 weeks of gestation. Groups were defined as following: A) culture-proven or probable EOS (n = 25); B) Possible EOS, based on risk factors for which antibiotics were administered for <72 h (n = 49); C) Risk factor(s) for EOS without need for antibiotic treatment (n = 181); D) Healthy controls (n = 74). Additionally, venous or capillary blood PCT and C-reactive protein (CRP) were tested if blood drawing was necessary for standard care. Results: Between June 2019 and March 2021, 329 newborns were included. Umbilical cord blood PCT was significantly higher in group A than in group C and D. No difference between venous or arterial samples was found. Sensitivity and specificity for cord blood procalcitonin were 83 and 62%, respectively (cut-off 0.1 ng/mL). Antepartum maternal antibiotic administration was associated with decreased PCT levels in both cord blood and infant blood directly postpartum in all groups combined. Conclusion: Umbilical cord blood PCT levels are increased in newborns ≥32 weeks with a proven or probable EOS and low in newborns with risk factors for infection, but PCT seems not a reliable marker after maternal antibiotic treatment. PCT could be useful to distinguish infected from healthy newborns with or without EOS risk factors.

Serum procalcitonin to differentiate acute antepartum pyelonephritis from asymptomatic bacteriuria and acute cystitis during pregnancy: A multicenter prospective observational study

OBJECTIVE

To examine whether serum procalcitonin (PCT) is useful for differentiating acute pyelonephritis (APN) from asymptomatic bacteriuria and acute cystitis during pregnancy.

METHODS

A multicenter prospective observational study was conducted to compare serum white blood cell (WBC) counts, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, and PCT level among pregnant women with asymptomatic bacteriuria, acute cystitis, and APN and healthy pregnant women (controls). Utility of WBC count, ESR, CRP, and PCT biomarkers for the prediction of APN during pregnancy were measured.

RESULTS

Area under the curve (AUC) values of PCT, CRP, ESR, and WBC count for predicting asymptomatic bacteriuria were 0.576, 0.628, 0.542, and 0.532, respectively; those for predicting acute cystitis were 0.766, 0.735, 0.681, and 0.597, respectively; and those for predicting acute pyelonephritis 0.859, 0.763, 0.711, and 0.732, respectively. Compared with the other inflammatory markers used to predict APN, PCT exhibited the highest AUC (0.859 [95% confidence interval (CI) 0.711-0.935]). A cutoff value of >0.25 ng/ml had a sensitivity of 87% and a specificity of 79%.

CONCLUSION

Serum PCT can be a valuable addition to existing methods of differentiating asymptomatic bacteriuria, acute cystitis, and APN during pregnancy and can facilitate the early identification of APN during pregnancy.

Diagnostic value of biomarkers for paediatric urinary tract infections in primary care: systematic review and meta-analysis

Background

Accurate diagnosis of urinary tract infection is essential as children left untreated may suffer permanent renal injury.

Aim

To compare the diagnostic values of biomarkers or clinical prediction rules for urinary tract infections in children presenting to ambulatory care.

Design and setting

Systematic review and meta-analysis of ambulatory care studies.

Methods

Medline, Embase, WOS, CINAHL, Cochrane library, HTA and DARE were searched until 21 May 2021. We included diagnostic studies on urine or blood biomarkers for cystitis or pyelonephritis in children below 18 years of age. We calculated sensitivity, specificity and likelihood ratios. Data were pooled using a bivariate random effects model and a Hierarchical Summary Receiver Operating Characteristic analysis.

Results

Seventy-five moderate to high quality studies were included in this review and 54 articles in the meta-analyses. The area under the receiver-operating-characteristics curve to diagnose cystitis was 0.75 (95%CI 0.62 to 0.83, n = 9) for C-reactive protein, 0.71 (95% CI 0.62 to 0.80, n = 4) for procalcitonin, 0.93 (95% CI 0.91 to 0.96, n = 22) for the dipstick test (nitrite or leukocyte esterase ≥trace), 0.94 (95% CI 0.58 to 0.98, n = 9) for urine white blood cells and 0.98 (95% CI 0.92 to 0.99, n = 12) for Gram-stained bacteria. For pyelonephritis, C-reactive protein < 20 mg/l had LR- of 0.10 (95%CI 0.04–0.30) to 0.22 (95%CI 0.09–0.54) in children with signs suggestive of urinary tract infection.

Conclusions

Clinical prediction rules including the dipstick test biomarkers can support family physicians while awaiting urine culture results. CRP and PCT have low accuracy for cystitis, but might be useful for pyelonephritis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-021-01530-9.

Diagnostic test accuracy of point-of-care procalcitonin to diagnose serious bacterial infections in children

BACKGROUND

The National Institute for Health and Care Excellence (NICE) have called for research into the role of biomarkers, and specifically procalcitonin (PCT), for the early diagnosis of serious bacterial infections (SBI) in children. The aim of this study was to compare the diagnostic test accuracy of C-reactive protein (CRP) and PCT for the diagnosis of SBI in children.

METHODS

Data was collected prospectively from four UK emergency departments (ED) between November 2017 and June 2019. Consecutive children under 18 years of age with fever and features of possible sepsis and/or meningitis were eligible for inclusion. The index tests were PCT and CRP and the reference standard was the confirmation of SBI.

RESULTS

213 children were included in the final analysis. 116 participants (54.5%) were male, and the median age was 2 years, 9 months. Parenteral antibiotics were given to 100 (46.9%), three (1.4%) were admitted to a paediatric intensive care unit and there were no deaths. There were ten (4.7%) confirmed SBI. The area under the curve for PCT and CRP for the detection of SBI was identical at 0.70.

CONCLUSIONS

There was no difference in the performance of PCT and CRP for the recognition of SBI in this cohort.

TRIAL REGISTRATION

Registered at https://www.clinicaltrials.gov (trial registration: NCT03378258 ) on the 19th of December 2017.

Nursing Home-Associated Pneumonia, Part I: Diagnosis

Pneumonia is 1 of the 3 most common infections identified in nursing home residents and is associated with the highest mortality of any infection in this setting. In regard to pneumonia in the nursing home setting, practitioners are focused primarily on identifying residents with this infection and choosing a treatment regimen. In this article, the diagnosis of this infection is addressed. Based on published studies and clinical experience, "bedside criteria" for the diagnosis of nursing home-associated pneumonia (NHAP) are proposed that are based primarily on objective respiratory signs and symptoms that can be readily identified by staff. It is also stressed that factors predisposing to aspiration should be identified because there is a risk for aspiration pneumonitis. A previously published decision tool to distinguish between aspiration pneumonia and aspiration pneumonitis is discussed. Because providers are often not present when there is a change in status of a resident, nursing staff are crucial to the diagnosis of NHAP. However, there is variability in staff experience and the ability to obtain and communicate clinical findings to assist providers in making decisions about diagnosis. To deal with this issue, templates have been developed to help staff collect the appropriate information before contacting the provider. The most important diagnostic test in a resident with suspected pneumonia is a chest radiograph. However, studies done more than a decade ago demonstrated considerable variability in radiologists' interpretation of chest radiographs of residents performed in the nursing home. Radiologic techniques have improved considerably with utilization of digital technology, but there have been no recent studies to determine if interpretation of these radiographs is more consistent. An alternative to radiographs is lung ultrasonography, which has been found to be more accurate than chest radiographs in identifying pneumonia in adults; however, this method has not been studied in the nursing home setting. Host biomarkers such as serum C-reactive protein and procalcitonin levels have been studied in adults with pneumonia to distinguish between bacterial and nonbacterial infection, but there has been limited study in NHAP and the findings are conflicting. Lastly, it is stressed that the provider should carefully document the clinical findings and testing that result in a diagnosis of pneumonia to enhance surveillance for infection as well as antimicrobial stewardship activities.