Prevalence of Fungi in Primary Endodontic Infections of a Greek-living Population Through Real-time Polymerase Chain Reaction and Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

Introduction Fungi are considered to be opportunistic pathogens that may play a significant role in the pathogenesis of endodontic infections. The main purpose of the study was to assess the prevalence of two selected genera of fungi, namely Candida albicans and Aspergillus spp. by using Real Time-Polymerace Chain Reaction (RT-PCR) and to compare the findings with the respective ones obtained by a culture-dependent approach, the Matrix-assisted laser desorption/ionization Time of Flight Mass Spectrometry (MALDI-ToF MS). A secondary aim was to assess the presence of other bacteria growing under aerobic conditions. Methods Microbial samples were obtained from root canals of 60 teeth associated with pulp necrosis and apical periodontitis. DNA was extracted and RT-PCR was applied for detection of C. albicans and Aspergillus spp. pathogenic subtypes. In addition, MALDI-ToF MS was performed to identify microorganisms grown under aerobic conditions. Results Based on RT-PCR, Aspergillus was detected in 8 cases whereas C. albicans in 4 cases. Using MALDI-ToF MS, no trace of Aspergillus was detected whereas C. albicans identified in two cases. Significant differences were revealed in the detection potential for the Aspergillus spp. between MALDI-ToF MS and RT-PCR (p=0.01); conversely, this was not the case for C. albicans (p=0.50). Following MALDI-ToF MS, 35 samples showed evidence of bacterial growth. The vast majority was colonized by Achromobacter xylosoxidans, followed by Lactobacillus spp., Methylobacterium spp. and Enterococcus faecalis. Conclusions The findings confirm the presence of fungi in primarily infected canals with apical periodontitis as well as of some rarely inspected aerobic bacterial species. A. xylosoxidans was prevalent, while the clinical relevance of its presence is deemed to be further investigated.