Impact of Bacterial Etiology on Procalcitonin, C-reactive Protein and Hematological Parameters: Evaluating Mean Platelet Volume for Differentiating Gram-Negative and Gram-Positive Bacteria in Odontogenic Versus Non-odontogenic Head and Neck Abscesses.

Introduction Head and neck abscesses, which can originate from odontogenic or non-odontogenic sources, pose significant diagnostic challenges due to their diverse bacterial etiologies. This study aims to investigate the impact of bacterial etiology on procalcitonin (PCT), C-reactive protein (CRP), and various hematological parameters, and to assess the diagnostic performance of mean platelet volume (MPV) in differentiating between Gram-negative bacteria (GNB) and Gram-positive bacteria (GPB) in adults with odontogenic and non-odontogenic head and neck abscesses. Materials and methods Our retrospective analysis of a prospective study comprised 80 patients: 50 individuals (56% men, average age 41.6±18.18 years) with odontogenic and 30 patients (66.7% men, average age 44.53±15.49 years) with non-odontogenic head and neck abscesses during the period from July 2021 to June 2022. White blood cell count (WBC); neutrophil (Neu) and lymphocyte (Ly) count; MPV, and platelet count (PLT) were derived from the results of complete blood count. MPV/PLT (MPI) was calculated by dividing MPV by PLT. CRP levels (mg/l) were quantified via immunoturbidimetric analysis utilizing latex-enhanced particles and PCT levels (ng/ml) by latex-enhanced immunoturbidimetric assay. Results In 25 (31.3%) of all 80 patients, no microorganisms were isolated (sterile cultures); in 28 (35%) resident microflora were isolated; in seven (8.8%) GNB were isolated; and in 17 (21.3%) GPB were isolated. CRP and Neu were significantly higher in patients with odontogenic abscesses compared to non-odontogenic ones. PLT and PCT were lower in patients with odontogenic abscesses vs those with non-odontogenic abscesses. Additionally, according to bacterial type, MPV, MPI and PCT were significantly higher in GPB compared to GNB. WBC, Neu and PLT were higher in patients with GNB vs GPB. Significant correlations were found between MPV and Ly, and between MPV and Neu, regardless of the abscess origin or etiological factor. MPI exhibited an area under the curve of the receiver operating characteristic (AUC-ROC)=0.776, MPV of 0.541, and PCT of 0.568 in distinguishing patients with GPB from GNB. A cut-off value of 0.029 was derived for MPI (70.6% sensitivity and 80% specificity). Conclusions This study highlights the impact of bacterial etiology on inflammatory and hematological markers in head and neck abscesses. Odontogenic abscesses showed higher CRP and Neu, indicating a stronger inflammatory response, while non-odontogenic abscesses had higher PLT, Ly, and PCT. MPI proved to be a more effective diagnostic marker (cut-off value of 0.029) than MPV or PCT for distinguishing between GPB and GNB, suggesting its valuable role in clinical practice for accurate and timely diagnosis.