Glove Contamination during Endodontic Treatment Is One of the Sources of Nosocomial Endodontic Propionibacterium acnes Infections

IntroductionThe opportunistic Propionibacterium acnes recovered frequently from failed endodontic treatments might be the result of nosocomial endodontic infections. The study was aimed to determine if gloves worn by dentists could be one of the sources of these nosocomial infections and to investigate the P. acnes phylotypes involved.MethodsThe cultivable microbiota of gloves (n = 8) at 4 time points (T1, immediately after wearing gloves; T2, after access cavity preparation; T3, after taking a working length/master cone radiograph; and T4, before sealing the cavity) were identified using 16S ribosomal RNA gene sequencing. recA gene sequencing of P. acnes isolates was done. The phylogenetic relationship was determined using MEGA 6 (http://www.megasoftware.net/fixedbugs.html; Megasoftware, Tempe, AZ). Data distributions were compared using the Fisher exact test; means were compared using the Mann-Whitney U test in SPSSPC (version 21; IBM, Armonk, NY).ResultsThe quantitative viable counts at T4 (aerobically [2.93 ± 0.57], anaerobically [3.35 ± 0.43]) were greater (P < .001) than at T1 [(aerobically [0.48 ± 0.73], anaerobically [0.66 ± 0.86]) and T2 (aerobically [1.80 ± 0.54], anaerobically [2.41 ± 0.71]). Eighty cultivable bacterial taxa (5 phyla) were identified. The most prevalent ones were P. acnes and Staphylococcus epidermidis (100%). recA gene sequencing (n = 88) revealed 2 phylogenetic lineages with type I split into type IA and type IB. Type II was prevalent on gloves.ConclusionsContamination of the gloves was detected at the final stages of the treatment. P. acnes and S. epidermidis are the prevalent taxa on gloves and are opportunistic endodontic pathogens. Changing gloves frequently, after gaining access into the pulp space and also after taking the working length/master gutta-percha point radiographs, is likely to reduce the risk of root canal reinfection.