Biomarkers to improve rational antibiotic use in low-resource settings

Anticipating the future: prognostic tools as a complementary strategy to improve care for patients with febrile illnesses in resource-limited settings

In low-income and middle-income countries, most patients with febrile illnesses present to peripheral levels of the health system where diagnostic capacity is very limited. In these contexts, accurate risk stratification can be particularly impactful, helping to guide allocation of scarce resources to ensure timely and tailored care. However, reporting of prognostic research is often imprecise and few prognostic tests or algorithms are translated into clinical practice.

Here, we review the often-conflated concepts of prognosis and diagnosis, with a focus on patients with febrile illnesses. Drawing on a recent global stakeholder consultation, we apply these concepts to propose three use-cases for prognostic tools in the management of febrile illnesses in resource-limited settings: (1) guiding referrals from the community to higher-level care; (2) informing resource allocation for patients admitted to hospital and (3) identifying patients who may benefit from closer follow-up post-hospital discharge. We explore the practical implications for new technologies and reflect on the challenges and knowledge gaps that must be addressed before this approach could be incorporated into routine care settings.

Our intention is that these use-cases, alongside other recent initiatives, will help to promote a harmonised yet contextualised approach for prognostic research in febrile illness. We argue that this is especially important given the heterogeneous settings in which care is often provided for patients with febrile illnesses living in low-income and middle-income countries.

Value of C-reactive protein in differentiating viral from bacterial aetiologies in patients with non-malaria acute undifferentiated fever in tropical areas: a meta-analysis and individual patient data study

C-reactive protein (CRP) is used to discriminate common bacterial and viral infections, but its utility in tropical settings remains unknown. We performed a meta-analysis of studies performed in Asia and Africa. First, mean CRP levels for specific tropical infections were calculated. Thereafter, individual patient data (IPD) from patients with non-malarial undifferentiated fever (NMUF) who were tested for viral and bacterial pathogens were analysed, calculating separate cut-off values and their performance in classifying viral or bacterial disease. Mean CRP levels of 7307 patients from 13 countries were dengue 12.0 mg/l (standard error [SE] 2.7), chikungunya 41.0 mg/l (SE 19.5), influenza 15.9 mg/l (SE 6.3), Crimean-Congo haemorrhagic fever 9.7 mg/l (SE 4.7), Salmonella 61.9 mg/l (SE 5.4), Rickettsia 61.3 mg/l (SE 8.8), Coxiella burnetii 98.7 mg/l (SE 44.0) and Leptospira infections 113.8 mg/l (SE 23.1). IPD analysis of 1059 NMUF patients ≥5 y of age showed CRP <10 mg/l had 52% sensitivity (95% confidence interval [CI] 48 to 56) and 95% specificity (95% CI 93 to 97) to detect viral infections. CRP >40 mg/l had 74% sensitivity (95% CI 70 to 77) and 84% specificity (95% CI 81 to 87) to identify bacterial infections. Compared with routine care, the relative risk for incorrect classification was 0.64 (95% CI 0.55 to 0.75) and the number needed to test for one extra correctly classified case was 8 (95% CI 6 to 12). A two cut-off value CRP test may help clinicians to discriminate viral and bacterial aetiologies of NMUF in tropical areas.

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

Empiric malaria treatment in Sub-Saharan Africa has significantly decreased with the scaling-up of malaria rapid diagnostic tests; this coincided with a pronounced increase in empiric antibiotic prescriptions. In high-income countries, guidance for antibiotic prescriptions using biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT) has reduced antibiotic use while safe-guarding patient safety. Importantly, several low-cost point-of-care CRP/PCT tests are currently available. However, only a few studies on the role of CRP/PCT in differentiating bacterial vs viral infections in acute febrile illness have been conducted in Sub-Saharan Africa. Studies from Central and West Africa (most of which is malaria-endemic) are particularly scarce, and only 1 has included adults. The evidence base for point-of-care use of CRP/PCT biomarkers in acute fever in Sub-Saharan Africa should be urgently built. Before engaging in clinical trials to assess clinical impact, pilot studies should be conducted to address key knowledge gaps including recommended CRP/PCT cutoff values and the effect of malaria coinfection.