Reduction Of Viable Bacterial Counts Research Articles

Comparative evaluation of the antibacterial activity of red diode laser therapy and 0.2% chlorhexidine against Aggregatibacter actinomycetemcomitans on implant healing abutments: An ex vivo study.

The intraoral microbiota has a high potential to undergo dysbiosis, causing inflammatory changes with respect to the tissues surrounding either a natural tooth or an implant. Thus, the longevity of implant prosthesis depends on a thorough implant decontamination protocol. Among all the techniques available for doing so, laser is garnering increasing popularity, owing to minimal bleeding, high efficiency, and faster healing. However, limited literature exists regarding the superiority of lasers over chlorhexidine (CHX), the indisputable gold standard antibacterial chemical agent. The aim of this study was to compare the percentage of bacterial reduction of Aggregatibacter actinomycetemcomitans from implant healing abutments post red diode laser therapy versus 0.2% CHX treatment. The current study had an ex vivo, observational, case-control design. Patients reporting for the second stage of the implant surgery were taken as the source of data and the healing abutments, the clinical samples. Eleven patients were chosen with one intraoral implant serving as the test site for laser treatment and another, the control site for CHX treatment. Microbiological analysis was performed via quantitative real time polymerase chain reaction to compare the bacterial reduction percentage after each treatment. Repeated measures ANOVA and independent sample t test were used. The mean bacterial viability of the test group (laser) was 1.2%-1.6%, and 0.6%-1.4% for the control group (CHX). The former caused a mean bacterial reduction of 96.1% while the latter, 96.3%. Both the treatments caused a highly statistically significant reduction of viable bacterial counts (P = 0.001). However, when compared, there was no statistically significant difference in the bacterial reduction, when compared in between the two (P = 0.902). Laser treatment is at par with chemical implant surface decontamination. It can help bypass the complications of CHX and revolutionize the protocols for implant surface decontamination.

The impact of gel fingernail polish application on the reduction of bacterial viability following a surgical hand scrub.

To determine the effect of gel nail polish application on the reduction of bacterial viability immediately after a surgical hand scrub. Randomized controlled trial. Ten fingernails each from 40 female health care professionals and students. Participants' fingernails were randomized to receive no polish or gel nail polish during a manicure from a licensed manicurist. One day and 14 days after manicure, participants' fingernails were sampled before and after a surgical hand scrub with chlorhexidine gluconate. The samples for each fingernail were serially diluted, plated on a Trypsin sheep blood agar and MacConkey's agar plate, and incubated for 36 h. For each plate, bacterial colony forming units (CFU)/ml were determined. Mixed linear models were used to assess factors associated with the logarithmic reduction of viable bacterial counts from pre- to post-surgical scrub. In the final model, no association was detected between gel nail polish and reduction of viable bacterial count (p=.09). On Day 14, among longer nail lengths (2 to <3-mm and ≥3-mm), surgical scrubs resulted in greater reduction in bacterial counts in left-handed than right-handed participants (p < .01). Increasing nail length was correlated with increased CFU/ml post-scrubbing (p < .001). Application of gel nail polish did not seem to affect the ability of surgical scrub to reduce bacterial viability 1 and 14 days after a manicure. This study does not provide evidence to prevent application of gel nail polish on short fingernails in surgeons prior to surgical hand scrub with chlorhexidine gluconate.

A multi-defense strategy: Enhancing bactericidal activity of a medical grade polymer with a nitric oxide donor and surface-immobilized quaternary ammonium compound.

A significant increase in the biomedical device related infections (BDRIs), inability of the currently existing antimicrobial strategies to combat them and a proportional rise in the associated morbidity demands development of novel antimicrobial surfaces. Some of the major challenges associated with the currently used therapeutics are: antibiotic resistance and cytotoxicity. In the current study, engineered polymeric composites with multi-defense mechanism were fabricated to kill bacteria via both active and passive mode. This was done by incorporating a nitric oxide (NO) donor S-nitroso-N-acetypenicillamine (SNAP) in a medical grade polymer (CarboSil®) and a benzophenone based quaternary ammonium antimicrobial small molecule (BPAM) was surface immobilized as the top layer. The developed biomaterial was tested with Gram-positive and Gram-negative strains and was found to be effective against both the strains resulting in up to 99.98% reduction in viable bacterial count. This preventative strategy can be used to fabricate implantable biomedical devices (such as catheters, stents, extracorporeal circuits) to not only significantly limit biofilm formation but also to reduce the antibiotic dose which are usually given post infections.

Efficacy of calcium hypochlorite and ultraviolet irradiation against Mycobacterium fortuitum and Mycobacterium marinum.

Nontuberculous mycobacteria (NTM) cause opportunistic infections with increasing frequency in immunocompromised humans. Water is one of the natural sources for transmission of NTM and plays a major role in the epidemiology of NTM infections. This study evaluated the efficacy of calcium hypochlorite and ultraviolet irradiation (UV) to eliminate potentially zoonotic NTM species such as M. marinum and M. fortuitum. Bacterial suspensions containing1-4 × 105 CFU/ml were exposed to 5, 50, 100, 1,000 and 10,000 mg/L of Ca (OCl)2for 1, 5, 10, 15, 20, 30 and 60 minutes, and 6,000 μW/cm2 UV dose for 5, 10, 20, 30, 60 and 120 seconds. Of the two methods tested, UV irradiation was more effective than chlorine in achieving three log reduction in viable bacterial count (UV dose 6,000 μW/cm2, exposure time 60 S) as well as in eliminating the organisms (UV dose 17,000 μW/cm2, exposure time: 30 S). When 10,000 mg/L of chlorine was used, 10 and 20 min contact times were required to achieve three log inactivation and complete elimination of M. fortuitum respectively. Our study suggest that initial disinfection of water by chlorine at the water treatment plant followed by UV irradiation at the household level would minimise the spread of NTM to the susceptible population via drinking water.

Effect of photoactivated disinfection using light in the blue spectrum

BackgroundLight in the blue spectrum is well known to cure composites. This in vitro-study was aimed to analyze a potential antimicrobial activity when combined with riboflavin as a photosensitizer. MethodsPhotoactivated disinfection (PAD) using a LED lamp emitting in the blue spectrum for 30s (PAD30) and 60s (PAD60) after application of 0.1% riboflavin was compared with a LED lamp emitting in the red spectrum with the respective photosensitizer (PADred). Killing activity was analyzed against planktonic 14 single species and a 12-species mixture with and without 25% serum. In addition, there was a reduction of viable bacterial counts in single species and a 12-species biofilm was measured after PAD. ResultsGram-positive bacteria were less sensitive to PAD30 and PAD60 than Gram-negatives. PAD60 decreased the counts by more than 3log10cfu in two of five Gram-positive and in six of nine Gram-negative strains, the total viable counts of the mixture were reduced by 1.04±0.46log10cfu. In the presence of 25% serum a decrease by more than 2log10cfu was only found in tests with one Porphyromonas gingivalis strain. PADred killed all included strains except for the 12-species mixture and Eubacterium nodatum. PAD60 reduced the counts in P. gingivalis biofilms by 2–3log10cfu, however there was no activity of PAD60 and PADred on the multi-species biofilm. ConclusionsPAD using LED emitting in the blue spectrum combined with riboflavin is active against periodontopathogenic microbial species but clearly inferior to PADred. Multi-species biofilms are not sensitive to PAD using LED.

An Engineered Human Antibody Fab Fragment Specific for Pseudomonas aeruginosa PcrV Antigen Has Potent Antibacterial Activity

Pseudomonas aeruginosa is an opportunistic pathogen that can cause acute lung injury and mortality through the delivery of exotoxins by the type III secretion system (TTSS). PcrV is an important structural protein of the TTSS. An engineered human antibody Fab fragment that binds to the P. aeruginosa PcrV protein with high affinity has been identified and has potent in vitro neutralization activity against the TTSS. The instillation of a single dose of Fab into the lungs of mice provided protection against lethal pulmonary challenge of P. aeruginosa and led to a substantial reduction of viable bacterial counts in the lungs. These results demonstrate that blocking of the TTSS by a Fab lacking antibody Fc-mediated effector functions can be sufficient for the effective clearance of pulmonary P. aeruginosa infection.

Stable concentrated emulsions of the 1-monoglyceride of capric acid (monocaprin) with microbicidal activities against the food-borne bacteria Campylobacter jejuni, Salmonella spp., and Escherichia coli.

Of 11 fatty acids and monoglycerides tested against Campylobacter jejuni, the 1-monoglyceride of capric acid (monocaprin) was the most active in killing the bacterium. Various monocaprin-in-water emulsions were prepared which were stable after storage at room temperature for many months and which retained their microbicidal activity. A procedure was developed to manufacture up to 500 ml of 200 mM preconcentrated emulsions of monocaprin in tap water. The concentrates were clear and remained stable for at least 12 months. They were active against C. jejuni upon 160- to 200-fold dilution in tap water and caused a >6- to 7-log(10) reduction in viable bacterial count in 1 min at room temperature. The addition of 0.8% Tween 40 to the concentrates as an emulsifying agent did not change the microbicidal activity. Emulsions of monocaprin killed a variety of Campylobacter isolates from humans and poultry and also killed strains of Campylobacter coli and Campylobacter lari, indicating a broad anticampylobacter activity. Emulsions of 1.25 mM monocaprin in citrate-lactate buffer at pH 4 to 5 caused a >6- to 7-log(10) reduction in viable bacterial counts of Salmonella spp. and Escherichia coli in 10 min. C. jejuni was also more susceptible to monocaprin emulsions at low pH. The addition of 5 and 10 mM monocaprin emulsions to Campylobacter-spiked chicken feed significantly reduced the bacterial contamination. These results are discussed in view of the possible utilization of monocaprin emulsions in controlling the spread of food-borne bacteria from poultry to humans.

Bactericidal Activity of Moxifloxacin Compared to Grepafloxacin and Clarithromycin against Streptococcus pneumoniae and Streptococcus pyogenes Investigated Using an In Vitro Pharmacodynamic Model

The aim of the present investigation was to study and compare the killing activity of two new fluoroquinolone compounds, moxifloxacin and grepafloxacin, and a new generation macrolide, clarithromycin, against three clinical isolates of Streptococcus pneumoniae (penicillin-susceptible, -intermediate and -resistant) and two Streptococcus pyogenes (erythromycin-suscepti-ble and -resistant) strains by simulating their human pharmacokinetics in a pharmacodynamic model. Results were achieved by measuring the reduction in viable bacterial count during the 24-h experimental period.All three antimicrobials led to a continuous reduction in the bacterial counts of penicillin-susceptible S. pneumoniae and erythromycin-susceptible S. pyogenes strains, the maximal reduction observed after 8-10 hours being 5-6 logs for moxifloxacin and 3 logs for grepafloxacin; clarithromycin exhibited a similar reduction of 5 logs only after 24 h. No regrowth was observed for any strain after 24 h with any of the antibiotics.The bactericidal activity of both the fluoroquinolones was not affected by penicillin resistance of S. pneumoniae and erythromycin resistance of S. pyogenes. In contrast, clarithromycin was not able to reduce the bacterial count of penicillin-resistant S. pneumoniae and erythromycin-resistant S. pyogenes strains.Moxifloxacin exhibited, within 24 h, higher and faster bactericidal activity than grepafloxacin and clarithromycin against S. pneumoniae, and was not affected by penicillin resistance. These results suggest that moxifloxacin is a promising new agent for treatment of streptococcal infections.

The effect of Sendai virus infection on bactericidal and transport mechanisms of the murine lung.

Pulmonary virus infections predispose to bacterial infections in the lung. The mechanism of this effect was studied by quantitative comparison of the effects of airborne acute viral infection on pulmonary transport vs. in situ bactericidal mechanisms in mice. Animals infected by aerosol with 10(4) TCID(50) of Sendai virus developed pathologic pulmonary changes of interstitial pneumonitis, bronchial epithelial desquamation, and peribronchial mononuclear cell infiltration 7 days later. At that time, the mice were challenged with an aerosol of viable (32)P-labeled Staphylococcus aureus. Pulmonary bactericidal activity and physical transport by the lung were determined by the determination of viable staphylococcal and (32)P radiotracer counts respectively at 4, 24, 48, and 72 hr after bacterial challenge. Infected mice showed a significant decrease from normal in the rate of reduction of viable bacterial counts in the first 4 hr after challenge followed by a proliferation of the staphylococci. By contrast, radiotracer removal rates at 4 and 24 hr were similar in infected and noninfected mice. There was a small but significant retention of (32)P in the lungs of the infected animals at the later periods. These data demonstrate that bacterial multiplication associated with virus infection of lungs is related to defects in in situ bactericidal (phagocytic) mechanisms rather than transport mechanisms of the lung, despite histologic evidence of extensive destruction of bronchial-ciliated epithelium.