Point-of-Care Biomarkers to Guide Antibiotic Prescription for Acute Febrile Illness in Sub-Saharan Africa: Promises and Caveats

Point-of-care diagnostics for infection and antimicrobial resistance in sub-Saharan Africa: A narrative review

OBJECTIVES

Sub-Saharan African (SSA) countries are severely impacted by antimicrobial resistance (AMR). Due to gaps in access to diagnostics in SSA, the true extent of AMR remains unknown. This diagnostic gap affects patient management and leads to significant antimicrobial overuse. This review explores how point-of-care (POC) testing for pathogen identification and AMR may be used to close the diagnostic gap in SSA countries.

METHODS

A narrative review exploring current clinical practice and novel developments in the field of POC testing for infectious diseases and AMR.

RESULTS

POC assays for identification of various pathogens have been successfully rolled out in SSA countries. While implementation studies have mostly highlighted impressive test performance of POC assays, there is limited data on the impact of implementation on clinical outcomes and cost-effectiveness. We did not encounter local studies of host-directed POC assays relevant to AMR. Novel POC assays using real-time polymerase chain reaction, isothermal amplification, microfluidics, and other technologies are in various stages of development.

CONCLUSIONS

Available literature shows that POC testing for AMR applications is implementable in SSA and holds the potential to reduce the diagnostic gap. Implementation will require effective regulatory pathways, incorporation of POC testing in clinical and laboratory guidelines, and adequate value capture in existing health financing models.

Comparison of commercially available, rapid, point-of-care C-reactive protein assays among children with febrile illness in southwestern Uganda

In Uganda, children with febrile illness are often treated with antibiotics even though most have self-limiting, likely viral, infections. C-reactive protein (CRP) measurement can help identify those who are more likely to have a bacterial infection and therefore need antibiotic treatment. Implementation of a CRP rapid diagnostic test (RDT) at the point-of-care in resource-constrained settings with minimal laboratory infrastructure could reduce unnecessary antibiotic use. In this study, we evaluated the performance of three semi-quantitative CRP RDTs (Actim, BTNX, Duo) against a reference CRP assay requiring an electrically powered analyzer (Afinion). While both tests demonstrated substantial agreement with Afinion, Actim had slightly higher agreement than BTNX. The sensitivity was higher for the BTNX test, whereas the Actim test had a higher specificity, at cut-offs of 40 mg/L and 80 mg/L. At a cut-off of 20 mg/L, Duo demonstrated substantial agreement with the Afinion test as well. Our results demonstrate the reliability of CRP RDTs when compared to a reference standard. CRP RDTs without the need for a laboratory-based analyzer are promising tools for optimizing antibiotic use in low-resource settings.

Circulating markers of neutrophil activation and lung injury in pediatric pneumonia in low-resource settings

Diagnostic biomarkers for childhood pneumonia could guide management and improve antibiotic stewardship in low-resource settings where chest x-ray (CXR) is not always available. In this cross-sectional study, we measured chitinase 3-like protein 1 (CHI3L1), surfactant protein D (SP-D), lipocalin-2 (LCN2), and tissue inhibitor of metalloproteinases-1 (TIMP-1) in Ugandan children under the age of five hospitalized with acute lower respiratory tract infection. We determined the association between biomarker levels and primary end-point pneumonia, indicated by CXR consolidation. We included 89 children (median age 11 months, 39% female). Primary endpoint pneumonia was present in 22 (25%). Clinical signs were similar in children with and without CXR consolidation. Broad-spectrum antibiotics (ceftriaxone) were administered in 83 (93%). Levels of CHI3L1, SP-D, LCN2 and TIMP-1 were higher in patients with primary end-point pneumonia compared to patients with normal CXR or other infiltrates. All markers were moderately accurate predictors of primary end-point pneumonia, with area under receiver operator characteristic curves of 0.66-0.70 (p<0.05 for all markers). The probability of CXR consolidation increased monotonically with the number of markers above cut-off. Among 28 patients (31%) in whom all four markers were below the cut-off, the likelihood ratio of CXR consolidation was 0.11 (95%CI 0.015 to 0.73). CHI3L1, SP-D, LCN2 and TIMP-1 were associated with CXR consolidation in children with clinical pneumonia in a low-resource setting. Combinations of quantitative biomarkers may be useful to safely withhold antibiotics in children with a low probability of bacterial infection.

One biomarker does not fit all: tailoring anti-infective therapy through utilization of procalcitonin and other specific biomarkers

INTRODUCTION

Considering the ongoing increase in antibiotic resistance, the importance of judicious use of antibiotics through reduction of exposure is crucial. Adding procalcitonin (PCT) and other biomarkers to pathogen-specific tests may help to further improve antibiotic therapy algorithms and advance antibiotic stewardship programs to achieve these goals.

AREAS COVERED

In recent years, several trials have investigated the inclusion of biomarkers such as PCT into clinical decision-making algorithms. For adult patients, findings demonstrated improvements in the individualization of antibiotic treatment, particularly for patients with respiratory tract infections and sepsis. While most trials were performed in hospitals with central laboratories, point-of-care testing might further advance the field by providing a cost-effective and rapid diagnostic tool in upcoming years. Furthermore, novel biomarkers including CD-64, presepsin, Pancreatic stone and sTREM-1, have all shown promising results for increased accuracy of sepsis diagnosis. Availability of these markers however is currently still limited and there is insufficient evidence for their routine use in clinical care.

EXPERT OPINION

In addition to new host-response markers, combining such biomarkers with pathogen-directed diagnostics present a promising strategy to increase algorithm accuracy in differentiating between bacterial and viral infections. Recent advances in microbiologic testing using PCR or nucleic amplification tests may further improve the diagnostic yield and promote more targeted pathogen-specific antibiotic therapy.

Point-of-care C-reactive protein and Xpert MTB/RIF Ultra for tuberculosis screening and diagnosis in unselected antiretroviral therapy initiators: a prospective diagnostic accuracy study

Background

Tuberculosis (TB), a major cause of death in people living with HIV (PLHIV), remains challenging to diagnose. Diagnostic accuracy data are lacking for promising triage tests, such as C-reactive protein (CRP), and confirmatory tests, such as sputum and urine Xpert MTB/RIF Ultra (Ultra), and urine LAM, without prior symptom selection.

Methods

897 PLHIV initiating antiretroviral therapy were consecutively recruited in settings with high TB incidence, irrespective of symptoms. Participants were offered sputum induction, with a liquid culture reference standard. First, we evaluated point-of-care CRP testing on blood, compared to the World Health Organization (WHO)-recommended four-symptom screen (W4SS) for triage (n=800). Second, we evaluated Xpert MTB/RIF Ultra (Ultra) versus Xpert MTB/RIF (Xpert) for sputum-based confirmatory testing (n=787), with or without sputum induction. Third, we evaluated Ultra and Determine LF-LAM for urine-based confirmatory testing (n=732).

Findings

CRP and number of W4SS symptoms had areas under the receiver operator characteristic curve of 0.78 (95% confidence interval 0.73, 0.83) and 0.70 (0.64, 0.75), respectively. For triage, CRP (≥10 mg/l) has similar sensitivity to W4SS [77% (68, 85) vs. 77% (68, 85); p>0.999] but higher specificity [64% (61, 68) vs. 48% (45, 52); p<0.001]; reducing unnecessary confirmatory testing by 138 per 1000 people and the number-needed-to-test from 6.91 (6.25, 7.81) to 4.87 (4.41, 5.51). Using sputum, which required induction in 31% (24, 39) of people, Ultra had higher sensitivity than Xpert [71% (61, 80) vs. 56% (46, 66); p<0.001] but lower specificity [98% (96, 100) vs. 99% (98, 100); p<0.001]. The proportion of people with ≥1 positive confirmatory result detected by Ultra increased from 45% (26, 64) to 66% (46, 82) when induction was done. Programmatically-done haemoglobin, triage test combinations, and urine tests showed comparatively worse performance.

Interpretation

Among ART-initiators in a high burden setting, CRP is a more specific triage test than W4SS. Sputum induction improves yield. Sputum Ultra is a more accurate confirmatory test than Xpert.

Funding

SAMRC (MRC-RFA-IFSP-01-2013), EDCTP2 (SF1401, OPTIMAL DIAGNOSIS), NIH/NIAD (U01AI152087).

Research in context

Evidence before this study: Novel triage and confirmatory tests are urgently needed for TB, especially in key risk groups like PLHIV. Many TB cases do not meet World Health Organization (WHO)-recommended four-symptom screen (W4SS) criteria despite accounting for significant transmission and morbidity. W4SS also lacks specificity, which makes onward referral of triage-positive people for expensive confirmatory testing inefficient and hampers diagnostic scale-up. Alternative triage approaches like CRP have promise, but have comparatively little data in ART-initiators, especially when done without syndromic preselection and using point-of-care (POC) tools. After triage, confirmatory testing can be challenging due to sputum scarcity and paucibacillary early-stage disease. Next generation WHO-endorsed rapid molecular tests (including Xpert MTB/RIF Ultra; Ultra) are a standard-of-care for confirmatory testing. However, there are no supporting data in ART-initiators, among whom Ultra may offer large sensitivity gains over predecessors like Xpert MTB/RIF (Xpert). The added value of sputum induction to augment diagnostic sampling for confirmatory testing is also unclear. Lastly, the performance of urine tests (Ultra, Determine LF-LAM) in this population requires more data.Added value of this study: We evaluated repurposed and new tests for triage and confirmatory testing using a rigorous microbiological reference standard in a highly vulnerable high-priority patient population (ART-initiators) regardless of symptoms and ability to naturally expectorate sputum. We showed POC CRP triage is feasible, performs better than W4SS, and that combinations of different triage approaches offer no advantages over CRP alone. Sputum Ultra has superior sensitivity to Xpert; often detecting W4SS-negative TB. Furthermore, without induction, confirmatory sputum-based testing would not be possible in a third of people. Urine tests had poor performance. This study contributed unpublished data to systematic reviews and meta-analyses used by the WHO to inform global policy supporting use of CRP triage and Ultra in PLHIV.Implication of all the available evidence: POC CRP triage testing is feasible and superior to W4SS and, together with sputum induction in people who triage CRP-positive should, after appropriate cost and implementation research, be considered for roll-out in ART-initiators in high burden settings. Such people should be offered Ultra, which outperforms Xpert.

The Clinical and Laboratory Profiles of Immunocompetent Patients With Short-Duration Fever With Neutropenia in a Tertiary Care Hospital in Pune, India

Background Management of a febrile patient is based on understanding the pathophysiology of an abnormal temperature and temperature regulation, impacts of fever, and its treatment. In the current study, we aimed to characterize and compare the epidemiological, etiologic, microbiological, serological, clinical, and outcome traits of febrile patients with acute neutropenia admitted to a tertiary care center in Western Maharashtra. Methods Adult patients with a history of fever of less than two weeks' duration and without any immunosuppressive state were screened with predefined inclusion and exclusion criteria. General and demographic information (age and gender), and clinical examinations (type and duration of fever) were recorded. Biochemical, hematologic (total and differential cell counts), and immunologic measurements (rapid malaria, dengue, Leptospira, and viral hepatitis antigen antibodies) were performed. Data were analyzed using an appropriate statistical package. Results A total of 403 (214 males) young adults (aged: 29±11 years) with clinical presentation of fever were studied. The majority (n=361, 89.6%) had low-grade continuous fever with an average duration of 3±1 (mean±standard deviation (SD)) days. Headache and myalgia were the common symptoms present, and patients had an average hospital stay of 4±1 days. Dengue (55%) was the most common cause of febrile neutropenia, and all patients recovered well without antibiotics and granulocyte colony-stimulating factor. The mean C-reactive protein (CRP) level was 61.4±4.4 mg/L. CRP and procalcitonin (PCT) were directly correlated with the degree of neutropenia and inversely correlated with total leucocyte count (TLC). Conclusions It was highlighted from this study that antibiotics are not necessary for viral infections that have been diagnosed to stop the development of secondary bacterial infections. A clinician should be aware of "when not to use antibiotics," or the world will soon have to deal with superbugs.

ACCURACY OF C-REACTIVE PROTEIN AND PROCALCITONIN FOR DIAGNOSING BACTERIAL INFECTIONS AMONG SUBJECTS WITH PERSISTENT FEVER IN THE TROPICS

Background

In low-resource settings, inflammatory biomarkers can help identify patients with acute febrile illness who do not require antibiotics. Their use has not been studied in persistent fever (defined as fever lasting for ≥7 days at presentation).

Methods

C-reactive protein (CRP) and procalcitonin (PCT) levels were measured in stored serum samples of patients with persistent fever prospectively enrolled in Cambodia, the Democratic Republic of Congo, Nepal, and Sudan. Diagnostic accuracy was assessed for identifying all bacterial infections and the subcategory of severe infections judged to require immediate antibiotics.

Results

Among 1838 participants, CRP and PCT levels were determined in 1777 (96.7%) and 1711 (93.1%) samples, respectively, while white blood cell (WBC) count was available for 1762 (95.9%). Areas under the receiver operating characteristic curve for bacterial infections were higher for CRP (0.669) and WBC count (0.651) as compared with PCT (0.600; P <.001). Sensitivity for overall and severe bacterial infections was 76.3% (469/615) and 88.2% (194/220) for CRP >10 mg/L, 62.4% (380/609) and 76.8% (169/220) for PCT >0.1 µg/L, and 30.5% (184/604) and 43.7% (94/215) for WBC >11 000/µL, respectively. Initial CRP level was <10 mg/L in 45% of the participants who received antibiotics at first presentation.

Conclusions

In patients with persistent fever, CRP and PCT showed higher sensitivity for bacterial infections than WBC count, applying commonly used cutoffs for normal values. A normal CRP value excluded the vast majority of severe infections and could therefore assist in deciding whether to withhold empiric antibiotics after cautious clinical assessment.

Immune and endothelial activation markers and risk stratification of childhood pneumonia in Uganda: A secondary analysis of a prospective cohort study

BACKGROUND

Despite the global burden of pneumonia, reliable triage tools to identify children in low-resource settings at risk of severe and fatal respiratory tract infection are lacking. This study assessed the ability of circulating host markers of immune and endothelial activation quantified at presentation, relative to currently used clinical measures of disease severity, to identify children with pneumonia who are at risk of death.

METHODS AND FINDINGS

We conducted a secondary analysis of a prospective cohort study of children aged 2 to 59 months presenting to the Jinja Regional Hospital in Jinja, Uganda between February 2012 and August 2013, who met the Integrated Management of Childhood Illness (IMCI) diagnostic criteria for pneumonia. Circulating plasma markers of immune (IL-6, IL-8, CXCL-10/IP-10, CHI3L1, sTNFR1, and sTREM-1) and endothelial (sVCAM-1, sICAM-1, Angpt-1, Angpt-2, and sFlt-1) activation measured at hospital presentation were compared to lactate, respiratory rate, oxygen saturation, procalcitonin (PCT), and C-reactive protein (CRP) with a primary outcome of predicting 48-hour mortality. Of 805 children with IMCI pneumonia, 616 had severe pneumonia. Compared to 10 other immune and endothelial activation markers, sTREM-1 levels at presentation had the best predictive accuracy in identifying 48-hour mortality for children with pneumonia (AUROC 0.885, 95% CI 0.841 to 0.928; p = 0.03 to p < 0.001) and severe pneumonia (AUROC 0.870, 95% CI 0.824 to 0.916; p = 0.04 to p < 0.001). sTREM-1 was more strongly associated with 48-hour mortality than lactate (AUROC 0.745, 95% CI 0.664 to 0.826; p < 0.001), respiratory rate (AUROC 0.615, 95% CI 0.528 to 0.702; p < 0.001), oxygen saturation (AUROC 0.685, 95% CI 0.594 to 0.776; p = 0.002), PCT (AUROC 0.650, 95% CI 0.566 to 0.734; p < 0.001), and CRP (AUROC 0.562, 95% CI 0.472 to 0.653; p < 0.001) in cases of pneumonia and severe pneumonia. The main limitation of this study was the unavailability of radiographic imaging.

CONCLUSIONS

In this cohort of Ugandan children, sTREM-1 measured at hospital presentation was a significantly better indicator of 48-hour mortality risk than other common approaches to risk stratify children with pneumonia. Measuring sTREM-1 at clinical presentation may improve the early triage, management, and outcome of children with pneumonia at risk of death.

TRIAL REGISTRATION

The trial was registered at clinicaltrial.gov (NCT04726826).

C-reactive protein as an early biomarker for malaria infection and monitoring of malaria severity: a meta-analysis

This study investigated whether C-reactive protein (CRP) can be used as a marker for the early detection and monitoring of malaria severity. Potentially relevant studies were searched in Medline (PubMed), Scopus, and Web of Science. Differences in CRP between (1) severe malaria and uncomplicated malaria, (2) uncomplicated malaria and asymptomatic malaria, (3) uncomplicated malaria and febrile/healthy controls, and (4) asymptomatic malaria and febrile/healthy controls were estimated using random-effects models. Twenty-nine studies were included for meta-analysis. The results of meta-analysis demonstrated higher mean CRP levels in (1) patients with severe malaria compared with uncomplicated malaria (p < 0.001, standard mean difference [SMD]: 1.52, 95% confidence interval [CI]: 0.91-2.12, I2: 95.1%), (2) patients with uncomplicated malaria than in those with asymptomatic malaria (p: 0.001, SMD: 1.65, 95% CI: 0.67-2.62, I2: 96.7%), (3) patients with uncomplicated malaria compared with febrile/healthy controls (p < 0.001, SMD: 2.38, 95% CI: 1.37-3.40, I2: 98.5%), and (4) patients with asymptomatic malaria compared with febrile/healthy controls (p < 0.001, SMD: 2.55, 95% CI: 1.60-3.50, I2: 99.2%). This study demonstrated CRP levels are a biomarker for the early detection and monitoring of malaria severity.

Combating Childhood Infections in LMICs: evaluating the contribution of Big Data Big data, biomarkers and proteomics: informing childhood diarrhoeal disease management in Low- and Middle-Income Countries

Despite efforts to reduce the global burden of childhood diarrhoea, 50% of all cases globally occur in children under five years in Low–Income and Middle- Income Countries (LMICs) and knowledge gaps remain regarding the aetiological diagnosis, introduction of diarrhoeal vaccines, and the role of environmental enteric dysfunction and severe acute malnutrition. Biomarkers may assist in understanding disease processes, from diagnostics, to management of childhood diarrhoea and the sequelae to vaccine development. Proteomics has the potential to assist in the identification of new biomarkers to understand the processes in the development of childhood diarrhoea and to aid in developing new vaccines. Centralised repositories that enable mining of large data sets to better characterise risk factors, the proteome of both the patient and the different diarrhoeal pathogens, and the environment, could inform patient management and vaccine development, providing a systems biological approach to address the burden of childhood diarrhoea in LMICs.

Procalcitonin for individualizing antibiotic treatment: an update with a focus on COVID-19

Procalcitonin (PCT) is useful for differentiating between viral and bacterial infections and for reducing the unnecessary use of antibiotics. As the rise of antimicrobial resistance reaches “alarming” levels according to the World Health Organization, the importance of using biomarkers, such as PCT to limit unnecessary antibiotic exposure has further increased. Randomized trials in patients with respiratory tract infections have shown that PCT has prognostic implications and its use, embedded in stewardship protocols, leads to reductions in the use of antibiotics in different clinical settings without compromising clinical outcomes. However, available data are heterogeneous and recent trials found no significant benefit. Still, from these trials, we have learned several key considerations for the optimal use of PCT, which depend on the clinical setting, severity of presentation, and pretest probability for bacterial infection. For patients with respiratory infections and sepsis, PCT can be used to determine whether to initiate antimicrobial therapy in low-risk settings and, together with clinical data, whether to discontinue antimicrobial therapy in certain high-risk settings. There is also increasing evidence regarding PCT-guided therapy in patients with coronavirus disease 2019 (COVID-19). This review provides an up-to-date overview of the use of PCT in different clinical settings and diseases, including a discussion about its potential to improve the care of patients with COVID-19.

Evaluation of C-reactive protein and myxovirus resistance protein A to guide the rational use of antibiotics among acute febrile adult patients in Northwest Ethiopia

OBJECTIVES

In low-resource settings, treatment is often given empirically without knowledge of the aetiology due to a lack of diagnostics. In the search for reliable rapid tests to guide treatment work-up, this study was performed to determine whether two biomarkers could differentiate bacterial from non-bacterial infections in acute febrile patients.

METHODS

Adults with acute fever were recruited at a referral hospital in Ethiopia. The QuikRead Go test was used to quantify C-reactive protein (qCRP) and the FebriDx test was used for combined qualitative detection of the bacterial CRP marker with myxovirus resistance protein A (MxA), a viral biomarker.

RESULTS

Of the 200 patients included in this study, most presented with 2-3 days of fever, headache, and joint pain. Antibiotics were prescribed for 83.5% and antimalarials for 36.5%, while a bacterial infection was only confirmed in 5% and malaria in 11%. The median qCRP level for confirmed bacterial infections was 128 mg/l. The FebriDx and QuikRead Go test had an overall agreement of 72.0%.

CONCLUSIONS

An over-prescription of antibiotics for febrile patients was observed, even for those with low CRP levels and without a confirmed bacterial infection. The added value of the FebriDx was limited, while the combined use of rapid tests for qCRP and malaria should be considered for the management of acute febrile illness and antibiotic stewardship.