Procalcitonin as a Biomarker of the Early Stage of Bacterial Infections in HIV/AIDS Patients

Abstract

We observed that low concentrations of procalcitonin (PCT) in the early stages of bacterial infection among HIV/AIDS patients are not always associated with a good prognosis. Many of our patients developed sepsis despite a PCT level of <0.5 ng/ml on the first days of infection. The aim of our study was to assess whether laboratory standards for PCT in patients with HIV/AIDS correlate with their clinical condition. We analyzed the concentration of PCT and other inflammatory markers in the early stages of bacterial infection among 40 HIV-infected patients and 52 AIDS patients enrolled for the study. The control group consisted of 37 healthy individuals. In comparison with PCT and WBC, PCT proved to be the most reliable in the early stages of bacterial infection. To conclude, we suggest new PCT cut-off ranges for HIV/AIDS patients with bacterial infection.In clinical practice, the most common cases have classical markers of inflammation such as C-reactive protein (CRP) serum concentration, white blood cell (WBC) count/mL and body temperature. These markers are neither specific nor sensitive enough to confirm the early stages of bacterial infection (l). CRP serum concentration can be higher than the normal range even in healthy individuals and various factors have an influence on CRP results. The WBC count among leucopenic patients often remains normal despite infection (2). The clinical symptoms of bacterial infections are often non-specific and confirming the presence of infection is difficult. The early confirmation of bacterial infections is particularly problematic among immunocompromised patients such as those who are HIVinfected. Their inflammatory response is sometimes less strong and the progress of infection faster than in patients without immune deficits. In immunocompromised patients, every elevation in the serum concentration of inflammatory markers, however slight, can be a sign of the onset of a disease. One of the most recently proposed inflammatory markers is PCT. This is a pro-hormone of calcitonin with a chain composed of 116 amino acids. PCT is released from the C-cells of the thyroid gland and plasma concentration is lower than 0.5 ng/mL, as measured using the immunoluminometric method (lLMA). During severe bacterial infections and sepsis, PCT is synthesized by leukocytes, macrophages, liver monocytes, the neuroendocrine cells ofthe lungs and intestines, with a serum concentration ofup to 1000.0 ng/mL (3). The results given in some publications suggest that PCT is also an important marker offungal infections and we can use it to differentiate bacterial from fungal infections (4). Jones et al. showed that

Procalcitonin level comparison in HIV/AIDS patients between non-bacterial and bacterial pneumonia in east Indonesia

“…Leukocytes and neutrophils levels did not have a significant difference between bacterial and non-bacterial pneumonia groups. The same result was also found by Mikula et al [14] Intracellular HIV replication in target cells express the CD4 receptor such as monocyte-macrophages, lymphocytes, neutrophils, and some eosinophils and basophils. Hence, the number of these cells was decreased by the destruction process [12].…”

“…This was in accordance with several previous studies that the diagnostic value of PCT was decreased and the value of PCT levels was hard to interpret in immunocompromised patients. Mikula et al [14] reported that the diagnostic value of procalcitonin decreased in the HIV group, which was 68% sensitivity and 8-11% specificity at a lower cut-off value of 0.16-0.17 ng/mL. Procalcitonin (PCT) levels in HIV patients could be influenced by several factors.…”

“…Second, HIV infection itself could affect plasma procalcitonin levels. Mikula et al [14] reported that among HIV patients without bacterial infection, levels of PCT could be normal or slightly increased. This can be explained due to HIV infection could activate the body's immune system through the expression of TLR on dendritic cells inducing IL6 and TNF-α production, which both inflammatory cytokines could induce PCT production [5].…”

“…While other publications reported that PCT value was hard to interpret. Instead, some authors have found that Creactive protein (CRP) was more effective than PCT for screening bacterial infection in HIV/AIDS patients [14]. Our research aimed to analyze the differences in the levels of procalcitonin between non-bacterial and bacterial pneumonia in patients with HIV/AIDS.…”