Low eosinophil counts associated with increased acute bacterial infection risk in older adults

1. This prospective study found that low eosinophil counts (< .01 g/L) were significantly associated with acute bacterial infection in older adults, and was more sensitive than a CIBLE score of > 87, but less specific. 

Evidence Rating Level: 2 (Good)

Sepsis is significantly associated with increased age, as is the incidence of bacterial infection. Oftentimes, older patients present atypically, typical inflammatory markers are not as reliable in this population, and they can be afflicted by distinct pathogens compared to their younger counterparts. The literature has suggested the association of eosinopenia in the acute stages of infection, with reliable sensitivity and specificity for bacterial infection. The current prospective study investigated the value of the eosinophil count in 156 older adult patients (≥ 75 years, mean 88.7, SD 5.9) with acute bacterial infections with fever (≥ 38 degrees Celsius) or inflammation (white blood cell [WBC] count > 10 g/L, C-reactive protein [CRP] > 20 mg/L). Of those with bacterial infections, pulmonary infections and urinary tract infections were most diagnosed conditions. Low eosinophil count (< .01 g/L) was found to be independently associated with acute bacterial infection (p < .001). Additionally, eosinophil counts below 0.01 g/L were more specific (84%) than a high CIBLE score (72%) for acute bacterial infection but were less sensitive (49%) than CIBLE scores (62%), which are composite scores that include: age, CRP, temperature, chronic obstructive pulmonary disease (COPD), and eosinophil/granulocyte ratios. The area-under-the-curve (AUC) was comparable between the two. Overall, these results indicate that eosinophil counts could prove useful as an accessible and inexpensive tool in the overall clinical picture and diagnosis of bacterial infection. Future studies should apply this protocol in multicentre trials to ensure generalizability.

Click to read the study in BMC Geriatrics

Image: PD

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