Molecular analysis for bacterial contamination

Bacterial contamination in dental unit waterlines (DUWLs) was evaluated by molecular techniques in addition to the conventional culture method. Water samples (n=8) from DUWLs were investigated for heterotrophic bacteria by culture method using R2A agar. The selected bacterial antibiotic-resistance genes and Legionella species-specific 16SrDNA were identified by PCR. The profiles of bacterial contamination in DUWLs were further identified by PCR-DGGE. In this study, no antibiotic-resistant or Legionella genes were detected. Polycyclic aromatic hydrocarbon-degrading bacterium, Novosphingobium sp. was the most prevalent in DUWLs. Conventional PCR and PCR-DGGE were shown to be potentially useful for monitoring of bacterial contamination in DUWLs

Bacterial-contamination Monitoring

Bacterial contamination of dental unit waterlines (DUWLs) was evaluated by using ATP-bioluminescence analysis and conventional culture method. Water samples (n=44) from DUWLs were investigated for heterotrophic bacteria by culture on R2A agar, which ranged from 1.4×103 to 2.7×105 CFU/mL. The ATP-bioluminescence results for DUWL samples were ranged from 6 to 1189 RLU and obtained within one minutes. These results were well correlated with the culture results (r=0.727-0.855). We conclude that differences in the bacterial contamination of each water supply were confirmed by the ATP-bioluminescence assay. This method would be potentially useful for rapid and simple monitoring of DUWL bacterial contamination

Use of ATP bioluminescence to survey the spread of aerosol and splatter during dental treatment

Aerosol and splatter produced during dental treatment (ultrasonic scaling and professional mechanical tooth cleaning) are potential sources of infection. Contamination patterns on the operators’ masks, goggles, chests and gowned right arms, and on the patients’ goggles, before and after dental treatment were investigated by using ATP bioluminescence analysis. Contamination on every surface tested increased significantly after dental treatment. Maximum contamination was found on patients’ goggles. Aerosol and splatter produced during dental treatment thus have the potential to spread infection to operators and patients. ATP bioluminescence is a useful tool for monitoring surface contamination

Molecular Epidemiology and Clinical Implications of Metallo-β-Lactamase-Producing Pseudomonas aeruginosa Isolated from Urine

We conducted a study on molecular epidemiology and clinical implications of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa isolated from urine. Over a 10-year period from 2001 through 2010, a total of 92 MBL-producing P. aeruginosa urine isolates were collected from patients (one isolate per patient) who were admitted to 5 hospitals in Okayama Prefecture, Japan. When cross-infection was suspected in the hospital, pulsed-field gel electrophoresis was performed. In the resulting dendrogram of 79 MBL-producing P. aeruginosa urine isolates, no identical isolates and 7 pairs of isolates with ≥80% similarity were found. The biofilm-forming capabilities of 92 MBL-producing P. aeruginosa urine isolates were significantly greater than those of 92 non-MBL-producing urine isolates in a medium of modified artificial urine. The imipenem resistance transferred in 16 of 18 isolates tested, and these frequencies were in the range of 10－3 to 10－9. All of 18 isolates tested belonged to internationally spread sequence type 235 and had 3 gene cassettes of antimicrobial resistance genes in the class 1 integron. The strong biofilm-forming capabilities of MBL-producing P. aeruginosa urine isolates could be seriously implicated in nosocomial infections. To prevent spread of the organism and transferable genes, effective strategies to inhibit biofilm formation in medical settings are needed

Detection of Identical Isolates of Enterococcus faecalis from the Blood and Oral Mucosa in a Patient with Infective Endocarditis

The detection of infective endocarditis (IE) of oral origin has been previously discussed. However, there are few reports confirming this infection using molecular biological techniques. We herein describe the case of a 67-year-old man who developed IE. Blood culture samples and strains obtained from the gingival and buccal mucosa showed 100% identity to Enterococcus faecalis JCM 5803 on sequencing of 16S rRNA gene fragments. A random amplification of polymorphic DNA (RAPD) analysis showed the same pattern for these samples, thus confirming the identity of E. faecalis isolates in the blood and oral mucosa. Our observations provide novel information regarding the level of identity between IE pathogens and oral bacteria

Role of O-6-methylguanine-DNA methyltransferase and effect of O-6-benzylguanine on the anti-tumor activity of cis-diaminedichloroplatinum(II) in oral cancer cell lines

The DNA repair enzyme, O-6-methylguanine-DNA methyltransferase (MGMT) modulates the effectiveness of alkylating agents. However, the relationship between MGMT and the sensitivities to other agents has not been explored. In the present study, the association between MGMT expression and the cellular sensitivity to the platinum agent, CDDP was examined in four human oral cancer cell tines. CDDP depleted MGMT protein and mRNA levels in all four cell tines. Two cell lines with low MGMT expression were sensitive to an alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine and CDDP, whereas two other cell tines with high MGMT expression were resistant to both agents. Furthermore, the addition of the MGMT inhibitor, O-6-benzylguanine (O-6-BG), invariably enhanced CDDP sensitivity. CDDP depleted MGMT expression, and CDDP sensitivity was enhanced by O-6-BG. These results provide valuable information about the relationship between MGMT expression and CDDP sensitivity in oral cancer chemotherapy. (c) 2005 Elsevier Ltd. All rights reserved. </p