LabMed

Antibiotic susceptibility testing (AST) reports classify isolates as “susceptible” despite potential undetected resistant subpopulations—a phenomenon termed susceptibility heterogeneity (SH). Found in 15–97% of clinical isolates of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, SH arises from heteroresistance or polyclonal diversity and may evade standard low-inoculum protocols. Clinically, this can lead to treatment failure, particularly in high-risk cases including immunocompromised patients, bloodstream infections, transplant recipients, and situations where minor resistant subpopulations significantly affect outcome. We argue that ethical principles of non-maleficence, transparency, and equity now compel laboratories to acknowledge this limitation. A simple annotation—“Limited susceptibility possible; resistant subpopulations may not be detected”—should accompany “susceptible” results in immunocompromised patients. High-risk cases warrant enhanced testing. This commentary calls for zone inspection, staff training, and Clinical and Laboratory Standards Institute (CLSI)/European Committee on Antimicrobial Susceptibility Testing (EUCAST) guideline updates to reflect SH. Transparency enhances clinical decision-making without implying diagnostic fault.

In the original publication [...]

Chronic heart failure (CHF) carries high morbidity and mortality. Circulating biomarkers of myocardial stretch, injury, and remodelling aids diagnosis and prognosis, but utility varies, especially in HFpEF, where natriuretic peptide (NP) values may be lower or normal in obesity. We systematically searched PubMed, Scopus, and Web of Science (2010–2025) for primary adult chronic-HF studies evaluating blood-based biomarkers: NPs, high-sensitivity troponins (hs-cTn), galectin-3, soluble ST2 (sST2), and microRNAs. Secondary sources (reviews/meta-analyses/guidelines) informed context only. Acute-HF studies were not pooled with chronic-HF analyses. Where appropriate, log hazard ratios were meta-analysed with random effects models. Twenty-nine studies met criteria. NT-proBNP remained the diagnostic/prognostic reference; across five prognostic cohorts, the pooled HR was 1.68 (95% CI 1.54–1.82; I² ≈ 55%). hs-cTn consistently improved risk stratification. Galectin-3 and sST2 were associated with adverse outcomes but typically provided modest incremental value beyond NPs/hs-cTn; galectin-3 is influenced by renal function, and sST2 is commonly interpreted around ~28–35 ng/mL. MicroRNAs (e.g., miR-21, miR-210-3p, miR-22-3p) showed promising yet heterogeneous signals across platforms and preanalytical workflows; therefore, findings were synthesised narratively without pooling. NT-proBNP and hs-cTn form the evidence-based backbone for biomarker-guided assessment in chronic HF. Galectin-3 and sST2 add adjunct prognostic information, while microRNAs remain investigational, pending standardised methods and external validation. Overall, evidence supports a multimarker, phenotype-tailored approach, with core NPs + hs-cTn and selective adjunct use of sST2/galectin-3 in context (HFrEF vs. HFpEF, obesity, renal function) to refine risk stratification and guide clinical decision-making.