Platelet dysfunction and inhibition of multiple electrode platelet aggregometry caused by penicillin

Beta-lactam antibiotics, e.g. penicillin, may inhibit platelet function and lead to reduced response in light transmission aggregometry and adhesion. However, influence on platelet function tests more commonly used in clinical practice, such as multiple electrode platelet aggregometry (MEA), have not been described so far. We report a case of a patient with local streptococcus infection. Treatment with penicillin resulted in mild bleeding tendency after 3 days. While coagulation parameters were normal, assessment of platelet function by MEA revealed strong platelet inhibition of both ADP and arachidonic acid induced platelet aggregation comparable to normal responders to antiplatelet therapy. Change of antibiotic regime resulted in recovery of platelet function. Thus, penicillin therapy may impact on platelet function and consecutively commonly used platelet function assays, e.g. MEA

Plasma TF activity predicts cardiovascular mortality in patients with acute myocardial infarction

<p>Abstract</p> <p>Objectives and Background</p> <p>Tissue factor (TF) contributes to thrombosis following plaque disruption in acute coronary syndromes (ACS). Aim of the study was to investigate the impact of plasma TF activity on prognosis in patients with ACS.</p> <p>Methods and Results</p> <p>One-hundred seventy-four patients with unstable Angina pectoris (uAP) and 112 patients with acute myocardial infarction (AMI) were included with a mean follow up time of 3.26 years. On admission, plasma TF activity was assessed. Patients were categorized into 2 groups: a high-TF activity group with TF >24 pmol/L and low TF activity group with TF ≤ 24 pmol/L. Fifteen cardiovascular deaths occurred in the uAP group and 16 in the AMI group. In AMI TF activity was 24,9 ± 2,78 pmol/l (mean ± SEM) in survivors and 40,9 ± 7,96 pmol/l in nonsurvivors (P = 0.024). In uAP no differences were observed (25.0 ± 8.04 pmol/L nonsurvivors vs. 25.7 ± 2.14 pmol/L survivors; P = 0.586). Kaplan-Meier estimates of survival at 3.26 years regarding TF activity in AMI were 81.3% and 92.2% with an hazard ratio of 3.02 (95% CI [1.05–8.79], P = 0.03). The Cox proportional hazards model adjusting for correlates of age and risk factors showed that plasma TF activity was an independent correlate of survival (hazard ratio 9.27, 95% CI [1.24–69.12], P = 0.03). In an additional group of patients with uAP and AMI, we identified circulating microparticles as the prevailing reservoir of plasma TF activity in acute coronary syndromes.</p> <p>Conclusion</p> <p>Systemic TF activity in AMI has an unfavorable prognostic value and as a marker for dysregulated coagulation may add to predict the atherothrombotic risk.</p