Combined effect of a mixture of tetracycline, acid, and detergent, and Nisin against Enterococcus faecalis and Actinomyces viscosus biofilms

To evaluate the combined effect of a mixture of tetracycline, acid, and detergent [MTAD] and Nisin against Enterococcus faecalis [E. faecalis] and Actinomyces viscosus [A. viscosus] biofilms. This study was conducted between June and December 2013 in collaboration with Dental Caries Research Chair, College of Dentistry, King Saud University, Riyadh, Saudi Arabia. Single-species biofilms [n=9/species/observation period] were generated on membrane filter discs and subjected to 5, 10, or 15 minute incubation with MTADN [MTAD with 3% Nisin], 5.25% sodium hypochlorite [NaOCl], or normal saline. The colony forming units were counted using the Dark field colony counter. A 100% bactericidal effect of 5.25% NaOCl was noted during the 3 observation periods; a significant reduction [p=0.000] in mean survival rates of E. faecalis [77.3+13.6] and A. viscosus [39.6+12.6] was noted after 5 minutes exposure to MTADN compared with normal saline [78000000+5291503] declining to almost no growth after 10 and 15 minutes. The survival rates of the E. faecalis and A. viscosus biofilm were no different after treatment with MTADN and 5.25% NaOCl at the 3 observation periods [p=1.000]. A combination of MTAD and Nisin was as effective as NaOCl against E. faecalis and A. viscosus biofilms

Cytotoxic effect of Salvadora persica extracts on human gingival fibroblast cells

To assess the cytotoxic potential of Salvadora persica [S. persica] extracts on human gingival fibroblast [HGF] cells. This study was conducted between January and May 2012 in collaboration with Dental Caries Research Chair, College of Dentistry, King Saud University, Riyadh, Saudi Arabia. Extracts of S. persica using hexane, ethylacetate, and ethanol as solvents at concentrations of 0.5 mg/ml and 1 mg/ml were evaluated for their cytotoxic activity against HGFs using the 3 cytotoxic assays: [3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide, a tetrazole] [MTS], lactic dehydrogenase [LDH], and crystal violet [CV]. International standards for the evaluation of medical materials recommended cut-off value of cell survival >70% was used for interpretation of the results. Ethanol extract of S. persica at 0.5 mg/ml and 1 mg/ml and hexane extract of S. persica at 0.5 mg/ml were completely devoid of cytotoxic activity, hexane extract at 1 mg/ml in comparison with controls demonstrated some cytotoxicity with cell survival of 88% [p=0.045] in MTS, 86% [p=0.01] in LDH, and 88% [p=0.002] in CV assays. Similarly, ethyl acetate extract of S. persica at 0.5 mg/ml maintained cell viability of 91% in MTS, 81% in LDH, and 80% in CV assays. Maximum cytotoxicity against HGFs was observed with ethyl acetate extract of S. persica at 1 mg/ml with cell survival of 60% in MTS, 40% in LDH, and 66% CV assays [p=0.0001]. The acceptable level of cytotoxicity associated with S. persica ethanol and hexane extracts requires further evaluation to be used as irrigation solutions in endodontic treatment

Antimicrobial susceptibility patterns of multidrugresistant Pseudomonas aeruginosa and Acinetobacter baumannii against carbapenems, colistin, and tigecycline

To examine susceptibility of Pseudomonas aeruginosa [P. aeruginosa] and Acinetobacter baumannii [A. baumannii] against carbapenems along with colistin and tigecycline as alternative therapeutic options. A total of 117 strains of multidrug-resistant [MDR] non-fermenting Gram negative bacteria isolated from non-duplicate samples were collected consecutively. We included one sample from each patient [84 isolates of A. baumannii and 33 isolates of P. aeruginosa isolated from patients seen at King Khalid University Hospital, Riyadh, Saudi Arabia, from June to December 2010]. Isolates were identified by the MicroScan WalkAway 96 Plus system. The minimum inhibitory concentrations [MICs] were determined by E-test following the Clinical and Laboratory Standards Institute breakpoint recommendations. Most A. baumannii strains were resistant to imipenem [90.5%], meropenem [90.5%], and doripenem [77.4%]. Whereas, a higher percentage of P. aeruginosa was resistant to imipenem [90.9%], and meropenem [81.8%], only 39.4% were resistant to doripenem. Colistin had excellent activity against both A. baumannii [100%] and P. aeruginosa [93.9%], while 89.3% of A. baumannii strains were susceptible to tigecycline. Among the carbapenems, doripenem was found to be the most potent antimicrobial agent against P. aeruginosa, whereas colistin proved to be an effective alternative antimicrobial agent for treatment of A. baumannii or P. aeruginosa. Tigecycline remains the best therapeutic option for MDR A. baumannii