We face difficulties in treating persistent infections with the knowledge on the bacteria growing on in their free-floating planktonic form as in the laboratory. It is estimated that 99% of all bacteria exist in biofilms, community of bacterial cells, and 65% of all human bacterial infections involve biofilm, especially chronic infections. Bacterial biofilms are difficult to detect in routine diagnostics and inherently tolerant to host defenses and antibiotic therapies. Strategies directed against biofilms will become increasingly important in treating infections.
Bacteria ; Bacterial Infections ; Biofilms* ; Drug Resistance ; Humans ; Plankton

In the forensic practice, the reliability of diatom test as a supportive measure to diagnose drowning is still disputed, from trustworthy to worthless. Some of the reason for the controversy is low sensitivity of the test, possibility of postmortem contamination and the detection of diatom in the tissues of non-drowned body. However, there is a variation of the diatom flora by season and by locale and it is strongly correlated with the frequency of positive diatom test outcomes. Therefore, if there is a profile of the diatom flora at a site, it can be compared with the diatom genera found in tissues of the immersed bodies, and also the test result can be predicted or verified. On each season, at three aquatic locations where drowning victims are often found, the author collected water samples and examined the plankton species of the samples, including dominant species and total number of plankton by site and by season. The examination result showed 16 species of diatoms, 20 species of green algae, 6 species of cyanobacteria, and 6 species of other algae. There is an enormous difference of population of algae by site(39 cells ~ 37,180 cells), but conspicuous periodicity of types and numbers of algae is not noted by season and by depth.
Chlorophyta ; Cyanobacteria ; Diatoms ; Drowning ; Periodicity ; Plankton ; Seasons ; Water

The aim of this study was to investigate the susceptibility of Mutans streptococci in both planktonic and biofilm states to erythrosine.S. mutans was cultured in brain-heart infusion (BHI) broth. Erythrosine was diluted in BHI broth and prepared at a concentration range of 0.02 – 10000 µg/L. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured using the microdilution method. After forming biofilms on 96-well plates, the minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) were measured.S. mutans was susceptible to erythrosine in both planktonic and biofilm states. MIC and MBC values were both 19.5 µg/L for the planktonic state, while MBIC and MBEC values were 313 µg/L and 2500 µg/L, respectively, for the biofilm state.Erythrosine (19.5 µg/L) exhibited a bactericidal effect on S. mutans (killing 99.9%) in the planktonic state. For biofilms, erythrosine inhibited biofilm growth and eradicated 99.9% of biofilm bacteria at higher concentrations than MIC and MBC. These MBIC and MBEC concentrations are much lower than known noxious doses, and the MIC, MBC, and MBIC values were even lower than clinical concentrations.
Bacteria ; Biofilms ; Erythrosine ; Methods ; Microbial Sensitivity Tests ; Plankton

The acid digestion method for extracting diatoms has been widely used to confirm death by drowning, but its reliability is still disputed because some diatoms can be destroyed during the extraction process due to treatment with strong acid and heat. There is a need to develop an efficient and reliable digestive method to overcome the limitation of the present analytical procedure. In this study, the reliability and efficacy of quantitative and qualitative diatom analysis from seawater by an enzymatic digestion method was evaluated. We confirmed the merit of the enzymatic method that used proteinase K instead of nitric acid in the conventional method. As a result, the enzymatic method showed a higher recovery ratio and better preservation of the diatom structure, which is essential for quantitative (diatom density) and qualitative (species) interpretation of diatom analysis. This result indicates that the enzymatic method can replace the conventional acid digestion method to confirm cases of death by drowning since it is more reliable and yields conclusive results.
Diatoms ; Digestion ; Drowning ; Endopeptidase K ; Hot Temperature ; Nitric Acid ; Plankton ; Seawater

Salmonella enterica serovar Enteritidis is one of the major food borne pathogens. Utilizing lytic bacteriophages against this pathogen can be a new and effective approach for the prevention of food-contamination and food-borne infection. In this study, we isolated and characterized a Salmonella Enteritidis specific lytic bacteriophage (phage SE2). The bacteriolytic activity of planktonic and biofilmed cells against an antibiotic resistant strain of Salmonella Enteritidis was also evaluated. Phage SE2 revealed an efficient bacteriolytic effect with biofilm dispersing ability and could maintain its virulence even at extreme pH and temperature. It can be a potential biotherapeutic agent against Salmonella Enteritidis.
Bacteriophages ; Biofilms ; Drug Resistance ; Hydrogen-Ion Concentration ; Plankton ; Salmonella ; Salmonella enterica ; Salmonella enteritidis ; Sprains and Strains

A number of bacterial species coexist in oral cavities as a biofilm rather than a planktonic arrangement. By forming an oral biofilm with quorum sensing properties, microorganisms can develop a higher pathogenic potential and stronger resistance to the host immune system and antibiotics. Hence, the inhibition of biofilm formation has become a major research issue for the future prevention and treatment of oral diseases. In this study, we investigated the effects of pentose on biofilm formation and phenotypic changes using wild type oral bacteria obtained from healthy human saliva. D-ribose and D-arabinose were found to inhibit biofilm formation, but have no effects on the growth of each oral bacterium tested. Pentoses may thus be good candidate biofilm inhibitors without growth-inhibition activity and be employed for the future prevention or treatment of oral diseases.
Anti-Bacterial Agents ; Bacteria ; Biofilms ; Humans ; Immune System ; Pentoses ; Plankton ; Quorum Sensing ; Ribose ; Saliva

Staphylococcus aureus induces chronic infection in form of biofilm that exists in the host cells and arthroplastic prosthesis surface. In this study, the biofilm formation ability of S. aureus clinically isolated from bacteremia patients, biofilm processing and relationship of resistance to antibiotics, and difference of biofilm formation ability on different prosthetic material surfaces were studied. All of them formed biofilm and especially 6 strains of S. aureus had high ability of biofilm formation. In addition, it was found that some strains with higher biofilm formation ability make more higher polysaccharide layer production. When S. aureus ATCC 25923 forms biofilm, minimal bactericidal concentration (MBC) of biofilm bacteria is more increased than that of the planktonic state bacteria about one thousand folds. Especially, after 6 hours from starting on biofilm formation, the resistance to antibiotics was increased by more than 256 microgram/ml of MBC to every antibiotics and after 8 hours prominent increase (more than 4096 microgram/ml) was noted. Biofilm formation after bacterial adherence to plastic cover-slip was increased with time-dependent manner. Microcolonies were formed after 5 hours from a point that bacteria adhere to plastic cover-slip surface and after 6 hours biofilm was diffusely formed on entire surface, and then after 8 hours very thick biofilm was formed. Thicker biofilm was found on cobalt-chromium than titanium surface. These results suggest that titanium alloy materials are better than cobalt-chromium to minimize S. aureus biofilm formation on the arthroplastic material surface. Also, when microcolonies are formed after adherence of S. aureus to the arthroplastic material surface, resistance to antibiotics is starting.
Alloys ; Anti-Bacterial Agents ; Bacteremia ; Bacteria ; Biofilms ; Humans ; Plankton ; Plastics ; Prostheses and Implants ; Staphylococcus ; Staphylococcus aureus ; Titanium

In a photodynamic therapy, the difference of antibacterial capacity was compared according to the type of source of light when the same quantity of energy is irradiated.After S. mutans is formed in planktonic state and biofilm state, erythrosine diluted to 40 µM was treated for 3 minutes, and as the type of light source, Halogen, LED, and Plasma arc were used, which were irradiated for 30 seconds, 15 seconds and 9.5 seconds, respectively.After the completion of the experiment, CFU of each experiment arm was measured to compare the photodynamic therapeutic effects according to each condition.The CFU of each experiment arm had no statistically significant difference.Under the same quantity of energy, the photodynamic therapeutic effect can be said to be the same regardless of types of light source, which is a useful result in the clinical field with various light irradiators.
Arm ; Biofilms ; Erythrosine ; Photochemotherapy ; Plankton ; Plasma ; Streptococcus mutans ; Streptococcus ; Therapeutic Uses

Anti-Bacterial Agents/pharmacology* ; Biofilms ; Microbial Sensitivity Tests ; Peptides ; Plankton ; Staphylococcus epidermidis

OBJECTIVES: To compare the application effect of microwave digestion - vacuum filtration - automated scanning electron microscopy (MD-VF-Auto SEM) method and plankton gene multiplex PCR system in the diagnosis of drowning. METHODS: Lung, liver and kidney tissue of 10 non-drowning cases and 50 drowning cases were prepared for further MD-VF-Auto SEM method analysis and plankton gene multiplex PCR system analysis. The positive detection rate of the two methods in each tissue was calculated. RESULTS: The positive rate of the MD-VF-Auto SEM method detecting diatoms in drowning cases was 100%, and few diatoms were detected in the liver and kidney tissues of 6 non-drowning cases. By using the plankton gene multiplex PCR system, the diatom positive rate of drowning cases was 84%, and all the non-drowning cases were negative. There were significant differences in the positive rate of the liver, kidney tissues between MD-VF-Auto SEM method and plankton gene multiplex PCR system (P<0.05), as well as the total positive rate of cases. However, no significant differences were found in the positive rates of lung tissues (P>0.05). CONCLUSIONS MD-VF-Auto SEM method is more sensitive than plankton gene multiplex PCR system in diatom test. But the plankton gene multiplex PCR system can also detect plankton other than diatoms. Combination of the two methods can provide a more reliable basis for the diagnosis of drowning.
Diatoms/genetics* ; Drowning/diagnosis* ; Humans ; Liver ; Lung ; Microscopy, Electron, Scanning ; Multiplex Polymerase Chain Reaction ; Plankton/genetics*