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AIMS: Diagnosing acute heart failure (AHF) remains particularly challenging in older patients. Natriuretic peptides are recommended as valuable diagnostic tools in this context. This study aims to establish the diagnostic thresholds of B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) for AHF in patients aged over 75 years, both with and without co-morbidities. METHODS AND RESULTS: In this retrospective longitudinal multicentre cohort study, data were gathered from 12 071 hospitalized patients aged 75 years or older, presenting with acute dyspnoea and undergoing BNP or NT-proBNP measurement within 48 h of admission across 10 Assistance Publique-Hôpitaux de Paris facilities between 2011 and 2022, encompassing geriatrics, cardiology, and pulmonology departments. Final diagnoses were categorized using ICD-10 criteria as either AHF or other acute respiratory conditions such as COPD exacerbation, pulmonary embolism, and pneumonia. The mean (SD) age of the population was 84.0 (80.0, 89.0) years, with 52.7% being female. Out of these, 7946 (65.8%) were diagnosed with AHF upon discharge. For NT-proBNP, the identified 'optimal' threshold for diagnosing AHF was 1748 ng/L, with a positive predictive value (PPV) of 84%. Among patients aged over 85 years, a threshold of 2235 pg/mL for NT-proBNP was associated with an 84% PPV. In patients with atrial fibrillation (AF), a threshold of 2332 pg/mL for NT-proBNP demonstrated a PPV of 90% for AHF diagnosis. Additionally, in patients with an estimated glomerular filtration rate (eGFR) < 30 mL/min, a threshold of 3474 pg/mL for NT-proBNP yielded a 90% PPV for AHF diagnosis. In male patients, a threshold of 1800 pg/mL showed an 85% PPV for AHF diagnosis, while in patients with obesity, a threshold of 1375 pg/mL demonstrated an 85% PPV for AHF diagnosis. CONCLUSIONS: In older patients, we found significant effects of co-morbidities on natriuretic peptides results, particularly in patients over 85 years old, older patients with abnormal renal function, obesity, and atrial fibrillation. Despite the consideration of those co-morbid conditions, NT-proBNP and BNP level continue to demonstrate utility in the diagnosis of AHF in older patients.
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BACKGROUND: Helicobacter suis is a very fastidious microorganism associated with gastritis, gastric ulcers, and mucosa-associated lymphoid tissue lymphoma in humans. In vitro isolation of this agent from human patients has so far been unsuccessful. MATERIALS AND METHODS: A probe-based real-time PCR (RT-PCR) for the rapid detection of H. suis in gastric biopsies was developed. Secondly, a mouse-passage-based protocol was optimized for isolation of low numbers of viable H. suis bacteria. Mice were inoculated with different numbers of viable H. suis (102 -108 ) and kept for 4 weeks to allow multiplication of this pathogen. RESULTS: The probe-based real-time PCR (RT-PCR) exhibited a high degree of diagnostic specificity and analytical sensitivity, high linear correlations (r2 between 0.995 and 0.999), and high amplification efficiencies (>90%) for H. suis. No cross-reactivity was detected with human, porcine, non-human primate, and murine DNA nor with DNA from other bacteria including Helicobacter spp. and Campylobacter spp. H. suis was successfully re-isolated from the stomach of mice inoculated with at least 104 viable H. suis, using a biphasic medium (pH 5), consisting of Brucella agar with Brucella broth on top, both supplemented with vitox supplement, Campylobacter-selective supplement, amphotericin (5 µg/mL), HCl (0.05%), fetal bovine serum (20%), and linezolid (5 µg/mL). Linezolid was necessary to inhibit proliferation of contaminants, including lactobacilli. CONCLUSION: The methods described above can be implemented for detection or isolation of H. suis from human gastric biopsies.