The Reply

Abstract

We thank Dr Jolobe for his interest in our study dedicated to the clinical presentation of bacteremia in an older population,1Hyernard C Breining A Duc S Kobeh D Dubos M Prevel R et al.Atypical Presentation of Bacteremia in Older Patients Is a Risk Factor for Death.Am J Med. 2019; 132 (1344-52 e1)Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar and we agree with his comment pointing out that prevalence of bacteremia with an atypical presentation in older patients may have been underestimated in our study. In our clinical practice, the diagnosis of bacteremia is raised in presence of fever, chills, or sepsis, and blood cultures are then performed. In an older population, circumstances of blood culture collection should be different because of the atypical presentation of infection (absence of fever or presence of nonspecific symptoms like delirium or fall). Indeed, our study showed that among 151 consecutive patients with bacteremia enrolled, 21% did not present any of the classical signs of bacteremia. We totally agree that the full number of older patients with bacteremia during the enrollment period could have been underestimated for several reasons. The first may be the lack of blood culture collection because patients had no typical sign of bacteremia; they had such an atypical clinical presentation that the diagnosis of bacteremia was not suspected and blood sample not collected. The second reason, as suggested by Dr Jolobe, could be due to the lack of accuracy of blood collection to detect bacteria (because of prior use of antibiotics, insufficient quantity of blood collected, or non cultivable pathogen). To improve the accuracy of blood culture IDSA published recommendations in 2018 including at least 2 sets of blood culture bottles (2 aerobic and 2 anaerobic) with 10 mL of blood per bottle before antibiotic initiation.2Miller JM Binnicker MJ Campbell S Carroll KC Chapin KC Gilligan PH et al.A Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology.Clin Infect Dis. 2018; 67: e1-e94Crossref PubMed Scopus (93) Google Scholar In our study, 23% of patients received prior antibiotics and still had positive culture. Dr Jolobe suggests that the use of PCR may improve bacteria detection in blood. Indeed, recent reports support the use of PCR for identification of pathogens responsible for bacteremia. In a study conducted in Vietnam including 144 patients with sepsis, PCR performance to detect bacteria was higher than conventional blood culture (especially in case of prior antibiotic initiation) with a prognosis of improvement.3Trung NT Thau NS Bang MH Song LH PCR-based [email protected] test is superior in comparison with blood culture for identification of sepsis-causative pathogens.Sci Rep. 2019; 9: 13663Crossref PubMed Scopus (9) Google Scholar This technique is neither recommended nor available in our daily practice. Based on these encouraging results on PCR performance, studies deserve to be carried out especially in the older population. Dr Jolobe also emphasized the role of biomarkers like procalcitonin or C reactive protein to diagnose bacteremia with conflicting results in the literature. Interestingly, in our study, we looked at the reasons why blood cultures were sampled in absence of typical signs and noticed that an increased plasmatic concentration of C reactive protein without any obvious etiology led the physicians to suspect the diagnosis of bacteremia and to collect blood cultures. We concluded that adding this criterion to the other signs leading to collect blood culture could decrease the number of missed bacteremia diagnoses. This hypothesis also warrants further study. While our real-life study based on clinical approach warns physicians about atypical presentation (a fifth of older patients), hopefully future biomarkers may offer additional value by giving rise to the diagnosis of bacteremia as well as employing new technologies, such as PCR, for detecting bacteria in blood samples.