In vitro evaluation of the antimicrobial activity of chlorhexidine and sodium hypochlorite

The aim of this study was to investigate in vitro the antimicrobial activity of 0.2%, 1%, and 2% chlorhexidine gluconate (CHX gel and CHX liquid), against endodontic pathogens and compare the results with the ones achieved by 0.5%, 1%, 2.5%, 4%, and 5.25% sodium hypochlorite (NaOCl). A broth dilution test was performed, and the timing for irrigants to kill microbial cells was recorded and statistically analyzed. Both 2.0% gel and liquid formulations eliminated Staphylococcus aureus and Candida albicans in 15 seconds, whereas the gel formulation killed Enterococcus faecalis in 1 minute. All tested irrigants eliminated Porphyromonas endodontalis, Porphyromonas gingivalis, and Prevotella intermedia in 15 seconds. The timing required for 1.0% and 2.0% CHX liquid to eliminate all microorganisms was the same required for 5.25% NaOCl. The antimicrobial action is related to type, concentration, and presentation form of the irrigants as well as the microbial susceptibility.

Effects of a single inhalative exposure to formaldehyde on the open field behavior of mice

The effects of formaldehyde on the explorative behavior and locomotor activity of mice after a single inhalative exposure were examined in an open field. Adult male mice were exposed to approximately 1.1 ppm, 2.3 ppm, or 5.2 ppm formaldehyde vapour for 2 hours and the open field test was carried out two hours after the end of exposure (trial 1) and repeated 24 hours thereafter (trial 2). The following behavioral parameters were quantitatively examined: numbers of crossed floor squares (inner, peripheral, total), sniffing, grooming, rearing, climbing, and incidence of fecal boli. The results of the first trial revealed that the motion activity was significantly reduced in all exposed groups. In the 1.1 ppm group, the frequency of rearing was reduced and that of floor sniffing increased. The exposure to the two higher formaldehyde concentrations caused a significant decrease in total numbers of floor squares crossed by the subjects, air sniffing, and rearing. The open field test on the next day (trial 2) showed that the frequencies of floor sniffing, grooming, and rearing in all formaldehyde groups were significantly altered. In the 2.5 ppm group, an increased incidence of fecal boli was observed. From the results obtained, we conclude that the exposure of male mice to formaldehyde vapour affects their locomotor and explorative activity in the open field, and that some open field parameters are still altered in the exposed animals even after 24 hours.

Evaluation of the antibacterial potential of tetracycline or erythromycin mixed with calcium hydroxide as intracanal dressing against Enterococcus faecalis in vivo

OBJECTIVE

We evaluated the intracanal antibacterial potential of tetracycline or erythromycin mixed with calcium hydroxide (CH) against enterococci in vivo.

STUDY DESIGN

Fifty-five teeth in which enterococci were present were dressed for 1 month with either tetracycline (28 teeth) or erythromycin (27 teeth) mixed with CH.

RESULTS

The tetracycline mixture was effective against enterococci in 22 teeth (79%). In 7 teeth, other microorganisms were recovered, resulting in a total antimicrobial effect of 54%. The corresponding results for erythromycin were 96% and 56%.

CONCLUSIONS

The antimicrobial treatment of CH in combination with either erythromycin or tetracycline had a significant effect on enterococci, but the overall antimicrobial effect was relatively weak. Erythromycin mixed with CH seems to be a valuable option in the battle against monoinfections of enterococci.

Tissue-dissolution capacity and dentin-disinfecting potential of calcium hydroxide mixed with irrigating solutions

OBJECTIVE

The goal of this study was to compare the tissue-dissolution potential and antibacterial effectiveness of a conventional Ca(OH)(2)/saline paste with equivalent Ca(OH)(2)/NaOCl and Ca(OH)(2)/chlorhexidine digluconate medications.

STUDY DESIGN

Tissue specimens were obtained from freshly dissected pig palates. Tissue pieces of similar form and weight were incubated in air-tight containers with Ca(OH)(2) pastes or solutions proper for up to 7 days. Antimicrobial testing was performed in dentin blocks infected with Enterococcus faecalis. Medicated, sealed dentin specimens were incubated for 1 and 5 days, and bacterial growth was tested at different dentin depths.

RESULTS

Up to day 4, the Ca(OH)(2)/irrigating solution mixtures dissolved tissue more effectively than the conventional Ca(OH)(2)/saline paste. After 7 days, however, no statistically significant differences were found between the saline and hypochlorite mixtures, but the Ca(OH)(2)/chlorhexidine medication was significantly less effective. Dentin block disinfection was quicker and more thorough with the Ca(OH)(2)/chlorhexidine or the Ca(OH)(2)/NaOCl than with the Ca(OH)(2)/saline paste.

CONCLUSION

Ca(OH)(2)/irrigant mixtures under investigation appear more advantageous than the conventional Ca(OH)(2)/saline mixture, and merit further investigation in a clinical study.

Role of antimicrobial applications to the umbilical cord in neonates to prevent bacterial colonization and infection: a review of the evidence

In developing countries umbilical cord infections constitute a major cause of neonatal morbidity and pose significant risk for mortality, whereas outbreaks of cord infections continue to occur in developed country nurseries. Cord infections in developing countries can be prevented through increasing access to tetanus toxoid immunization during pregnancy, promoting clean cord care and reducing harmful cord applications and behaviors. Interventions introduced in both developed and developing countries to reduce exposure of the cord to infectious pathogens include clean cord cutting, hand-washing before and after handling the baby, bathing of the infant with antimicrobial agents and application of antimicrobials to the cord. Despite the importance of umbilical cord care, both traditionally and medically, there have been few randomized trials investigating the impact of different cord care regimens on rates of local or systemic infections, particularly in developing countries. This review examines available data on umbilical cord care, with a particular focus on those comparing rates of bacterial colonization and/or rates of cord infection among neonates receiving different umbilical cord care regimens. Although most investigators agree that topical antimicrobials reduce bacterial colonization of the cord, a firm relationship between colonization and infection has not been established. Further research in developed countries, including follow-up beyond hospital discharge, is required before advising on "best cord care practices." The paucity of published reports from developing countries indicates the need to investigate the impact of antimicrobial applications on cord and systemic infections in a community-based, prospective manner.

Evaluation of canal cleanliness and smear layer removal after the use of the Quantec-E irrigation system and syringe: a comparative scanning electron microscope study

OBJECTIVE

The purpose of this study was to evaluate canal cleanliness and smear layer removal after use of the Quantec-E irrigation system and to compare the system with traditional irrigation.

STUDY DESIGN

Forty anterior teeth were randomly assigned to 4 groups. Group A consisted of 15 teeth that were instrumented with .12, .10, .08, .06 and .04 tapered rotaries while simultaneously irrigated via the Quantec-E irrigation pump with 12 mL of 5.25% NaOCl, followed by 6 mL EDTA 17% in crown-down fashion, with a final flush with 4 mL 5.25% NaOCl. Group B consisted of 15 teeth that were instrumented with the same instrument sequence, and irrigated with the same volumes via traditional needle and syringe. Group C consisted of 5 teeth that were sectioned and examined under a scanning electron microscope (SEM) without any instrumentation and served as a negative control. Group D consisted of 5 teeth that were instrumented dry, without any irrigation, and served as a positive control. All teeth were sectioned buccolingually and examined with SEM at 700x magnification in the apical, middle, and coronal portions of the canals. Analysis of SEM images was performed by 5 independent examiners using a 4-point scoring system.

RESULTS

Irrigation with the Quantec-E irrigation pump resulted in cleaner canal walls, less debris, and more complete removal of the smear layer within the coronal one third, when compared with syringe irrigation. However, no difference was observed in the middle and apical one thirds of the root canal.

CONCLUSION

There was no significant difference between the 2 irrigation systems.

The effect of chlorhexidine as an endodontic disinfectant

OBJECTIVE

The purpose of this study was to establish whether addition of a 2% chlorhexidine rinse to a conventional treatment protocol enhances the rate of the successful disinfection of the root canal system in vivo.

STUDY DESIGN

Twenty-four teeth with infected necrotic pulps and resorbing apical periodontitis were treated with a conventional technique in which 1% NaOCl as irrigant was used. Half of the cases received an additional rinse with 2% chlorhexidine. Prereduced thioglycollate medium was used to take cultures that were incubated for 4 weeks.

RESULTS

Cultivable bacteria were retrieved at the conclusion of the first visit in 1 out of 12 chlorhexidine cases whereas in the control group 7 out of 12 cases showed growth. This difference was significant (P < .05).

CONCLUSION

The findings are clinically important.

Dibromoacetic acid-induced elevations in circulating estradiol: effects in both cycling and ovariectomized/steroid-primed female rats

Oral exposures to high concentrations of the drinking water disinfection by-product dibromoacetic acid (DBA) over the course of 14 days have been found to disrupt estrous cyclicity in the female rat. In order to investigate possible alterations in the relevant hormonal regulatory mechanisms, female Sprague-Dawley rats were gavaged for 2 weeks with 270 mg/kg DBA, ovariectomized (OVX) and implanted with estradiol capsules. For these females, the induced luteinizing hormone (LH) surge in these animals showed a borderline suppression in peak LH concentrations that was accompanied by a marked increase in circulating estradiol. This elevation in estradiol was DBA dose-related and, for intact, normally cycling females receiving lower doses of DBA (60 and 120 mg/kg, 14 days), was present on the day of estrus, at a time when a dramatic fall from proestrous concentrations is normally evident. Evaluations of liver microsomal cytochrome p450 activity in OVX/estradiol-implanted rats showed a suppression in ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-deethylase (PROD) activity (indications of the activity of CYP1A and 2B, respectively-two key enzymes in estradiol oxidative metabolism). Phenobarbital (PhB) exposure in these animals did show induction of this activity, but was unable to lower E2 concentrations. This suggests that a DBA-induced suppression in estradiol catabolism is present and may either involve a targeted effect on the estrogen binding site on the CYP2B1/2 and CYP1A genes apart from the PhB-responsive unit, or a second pathway (possibly sulfation) that is not PhB-inducible.

Pathological Effects of Formalin (37% Formaldehyde) Mixed in Feed or Administered into the Crops of White Leghorn Cockerels

This study compared the adverse effects of formalin administered by two different methods. Formalin mixed with the feed (2.5, 5.0 and 10 ml/kg) was given to 10-week-old White Leghorn cockerels for a period of 8 weeks. Simultaneously in other groups, a 3% solution of formalin was administered into the crops (5, 10, 15 and 20 ml/bird/day). Total amount of formalin utilized during the experiment in the feed of individual bird of groups given 2.5, 5 and 10 ml/kg was 6.25, 3.9 and 1.6% higher than those administered 5, 10 and 20 ml of 3% formalin into crop, respectively. Body mass and feed intake in all feed-mixed groups and those given 5 and 10 ml formalin (3%) into the crop were not significantly different from control. Administration of 15 and 20 ml formalin (3%) into crop resulted in depression, delayed onset of crowing, significantly decreased feed intake, lower body mass, decreased mass and volume of testes, ulceration in crops, sloughing of mucosa and petechial haemorrhages in proventriculus. All the groups given formalin had significantly smaller diameters of seminiferous tubules. Kidneys of the birds administered formalin into crop exhibited pyknotic nuclei of epithelial cells in proximal tubules. Non-significant differences in different parameters and lesser degree of pathological changes in birds given formalin-mixed feed than their corresponding crop-administered groups suggested that formalin present in the feed had partially evaporated. Therefore, birds ingested less amount of formalin than that originally mixed in the feed.

A microtiter-plate screening method for biofilm disinfection and removal

A quantitative spectrophotometric method was developed to measure the removal and killing efficacy of antibiofilm agents. Biofilms of Pseudomonas aeruginosa or Staphylococcus epidermidis were grown in 96-well plates, treated with an agent, then stained with either the biomass indicator crystal violet or the respiratory indicator 5-cyano-2,3-ditolyl tetrazolium chloride. This rapid screening method is sensitive enough to elucidate concentration-response relationships as well as differences between species responses to treatments. Using these assays, agents can be ranked by their ability to remove or kill biofilm.

Scedosporium prolificans osteomyelitis in an immunocompetent child treated with voriconazole and caspofungin, as well as locally applied polyhexamethylene biguanide

Scedosporium species are increasingly isolated from immunocompromised and immunocompetent patients. Unfortunately, Scedosporium infections are generally resistant to amphotericin B, and Scedosporium prolificans strains are particularly resistant to the antifungal agents now in use. We report here on an immunocompetent child with S. prolificans-associated osteomyelitis successfully treated with debridement, local irrigation with polyhexamethylene biguanide, and the systemic administration of voriconazole and caspofungin despite poor in vitro activity of voriconazole alone against the isolate. We also review the treatments and outcomes of 28 reported cases of osteomyelitis or septic arthritis caused by Scedosporium species in immunocompetent patients.

Clinical trial of chlorhexidine vaginal irrigation to prevent peripartal infection in nulliparous women

OBJECTIVE

The purpose of this study was to determine whether intrapartum chlorhexidine vaginal irrigations prevent peripartal infection in nulliparous women at >or=32 weeks of gestation.

STUDY DESIGN

This was a double-blinded, placebo-controlled randomized clinical trial. Vaginal irrigations were performed with 200 mL of 0.2% chlorhexidine solution or sterile saline solution placebo every 6 hours during labor. The primary study outcome was clinically diagnosed maternal peripartal infection: chorioamnionitis or endometritis. Analysis was by intent to treat.

RESULTS

One thousand forty-one women were assigned randomly to one of two groups (chlorhexidine therapy, 525 women; placebo, 516 women). The two groups were balanced for risk factors for infection. Rates of peripartal infection were 19.3% in the chlorhexidine group and 17.3% in the placebo group (relative risk 1.1; 95% CI, 0.9-1.4). Major and minor neonatal morbidities were similar between the groups. No major and one minor adverse reaction was attributed to chlorhexidine irrigation.

CONCLUSION

Under the conditions of this trial, chlorhexidine vaginal irrigation lacked efficacy in the prevention of clinically diagnosed maternal and neonatal infectious morbidity.

The antimicrobial effect of MTAD: an in vitro investigation

Pulp and periradicular diseases are of microbial origin. To effectively clean the root canal system a disinfecting agent must be able to penetrate into difficult-to-reach areas and kill microorganisms with minimal damage to the host tissues. The purpose of this investigation was to test the ability of a mixture of a tetracycline isomer, an acid, and a detergent (MTAD) to kill Enterococcus faecalis and compare its efficacy to that of sodium hypochlorite (NaOCl) and ethylene diamine tetraacetic acid (EDTA). The zones of inhibition and minimum inhibitory concentrations were measured for these solutions. Measurement of zones of inhibition and determination of the minimum inhibitory concentrations showed that MTAD is as effective as 5.25% NaOCl and significantly more effective than EDTA (p < 0.0001). Furthermore, MTAD is significantly more effective in killing E. faecalis than NaOCl when the solutions are diluted (p < 0.0001). Measurement of the minimum inhibitory concentrations demonstrated that although MTAD is still effective in killing E. faecalis at 200x dilution, NaOCl ceases to exert its antibacterial activity beyond 32x dilution. EDTA did not exhibit any antibacterial activity. Based on the results of this study, it seems that MTAD is an effective solution in eradicating E. faecalis.

In-use evaluation of Perasafe compared with Cidex in fibreoptic bronchoscope disinfection

The mycobactericidal activity of Perasafe (0.26% peracetic acid) was compared with that of Cidex (2% alkaline glutaraldehyde) by an in-use test. Fibreoptic bronchoscopes were artificially contaminated with Mycobacterium tuberculosis or Mycobacterium avium-intracellulare in sputum and, after manual pre-cleaning with a neutral soap, 10 and 20 min disinfection periods were tested. Perasafe was as effective as Cidex, thus requiring a 10 min disinfection period against M. tuberculosis and 20 min against M. avium-intracellulare. The results demonstrate that Perasafe is an effective disinfectant for use in reprocessing fibreoptic bronchoscopes.

Can toothpaste or a toothbrush with antibacterial tufts prevent toothbrush contamination?

BACKGROUND

Periopathogens and cariogenic species survive more than 48 hours on toothbrushes even under dry storage. This study examined a decontamination of toothbrushes by means of the bactericidal effect of different toothpastes or a special coating of the tufts.

METHODS

Eight untreated periodontitis patients were professionally brushed, using a new toothbrush per quadrant and 3 different toothpastes containing either amine/stannous fluoride (AmF/SnF2), amine fluoride (AmF), or a mild surfactant as major antibacterial component (excipient), or no paste (C). The brushes were rinsed and stored dry at room temperature. At different time intervals, 4 tufts per toothbrush were processed for selective and non-selective culturing procedures. The protocol was repeated comparing AmF/SnF2 and C with 2 toothbrushes with coated tufts (coat1 and coat2).

RESULTS

At baseline, C brushes (n = 16) harbored 10(7), 10(8), and 10(6) colony forming units (CFU) of aerobic, anaerobic, and black pigmented species, respectively. After 24 hours 10(6) CFU of aerobic and anaerobic species could still be cultured from 14 of the 16 brushes. Black-pigmented species remained detectable up to 4 hours; detection frequencies for Fusobacterium nucleatum and Streptococcus mutans at 24 hours were 5/16. With AmF/SnF2 and AmF toothpaste the number of adhering bacteria was already 2 log lower at baseline (P<0.05), but not for the excipient (0.5 log, P = 0.7). With AmF/SnF2 no vital species could be detected after 8 hours. AmF reduced the bacterial survival rate significantly more than the excipient, but less than AmF/SnF2 (P<0.05). The bactericidal effect of coat1 and coat2 was negligible when compared to C (P>0.20), and clearly inferior to the AmF/SnF2 paste (P<0.0001). After 24 hours these brushes still harbored >10(5) CFU.

CONCLUSIONS

Toothpastes can significantly reduce contamination of toothbrushes, but their bactericidal activity is dependent on their composition. Coated tufts failed to limit the bacterial contamination.

A survey of sodium hypochlorite use by general dental practitioners and endodontists in Australia

BACKGROUND

Sodium hypochlorite is used commonly as an endodontic irrigant, but there are no published reports that provide details of its use. This survey sought to determine the percentage of Australian dentists who practiced endodontics, whether they used sodium hypochlorite for irrigation, and the manner of dilution, storage and dispensing sodium hypochlorite used by both dentists and endodontists.

METHODS

All Australian endodontists and a stratified random sample of 200 general dentists in Australia were surveyed to address the issues identified above.

RESULTS

Almost 98 per cent of dentists surveyed performed endodontic treatment. Among endodontists, nearly 94 per cent used sodium hypochlorite for irrigation compared with just under 75 per cent of general dentists. Sodium hypochlorite use by general dentists was more common in Victoria and South Australia than in other States. An infant sanitizer (Milton or Johnson's Antibacterial Solution) was used by just over 92 per cent of general practitioners and by more than 67 per cent of endodontists. All other respondents used domestic bleach. One hundred and sixty four of the respondents (80 per cent of endodontists and over 90 per cent of general dentists) used a 1 per cent w/v solution. Ten practitioners used a 4 per cent w/v solution, five used a 2 per cent w/v solution and four used a 1.5 per cent w/v solution. Eighty per cent of the practitioners who diluted their sodium hypochlorite before use, used demineralized water for this purpose. The remainder used tap water. Only four practitioners stored sodium hypochlorite in a manner which risked light exposure and loss of available chlorine content.

CONCLUSIONS

Sodium hypochlorite is commonly used as an endodontic irrigant and Australian dentists generally stored the material correctly.

Glutaraldehyde inhalation exposure of rats: effects on lung morphology, Clara-cell protein, and hyaluronic acid levels in BAL

Glutaraldehyde (GA) is a biocide widely used in hospital and laboratory practice. GA is a volatile substance and, under certain circumstances, significant airborne concentrations may be generated at room temperature. Occupational exposure to GA by inhalation is suspected of causing delayed irritating effects. In recent years, GA has emerged as the main cause of occupational asthma among health-care workers. The aim of the present study was to evaluate effects of GA inhalatory exposure (0.025 ppm or 0.1 ppm, for 28 days) in rats exposed corresponding to the occupational shift cycle, at time point 24 h, 48 h, and 7 days postexposure (PE). Numerous vacuoles and dilated spaces in epithelial cells in bronchioles showing a destructive effect of GA on the cellular membrane were observed at 24 h PE in 0.1 ppm exposed rats. Lipid vacuoles observed after 48 h PE in higher GA exposure, in the Clara cells of the bronchial epithelium, and in endothelial cells of the alveolar capillaries are probably attributable to disturbed lipid metabolism. Many foci of collagen fibers were observed already after 7 days postexposure. Monitoring of inflammatory response and repair was made possible by using two biomarkers: Clara-cell protein (CC16) and hyaluronic acid (HA). Our results show that the inflammatory repair response contributed to progenitor Clara cells and HA plays a role in the development of fibrotic changes in the lung of rats. Glutaraldehyde in rats causes fibrotic effects at the actual threshold limit value-time weighted average (TLV-TWA) level for GA as specified by current Polish and other national regulations.

Bactericidal treatment of raw cotton as the method of byssinosis prevention

In early studies, research to control byssinosis focused on methods to reduce the trash in the textile mill environment. Dust control has been effective in reducing the prevalence of byssinosis, but simple reduction in dust levels does not always assure its prevention. Also, bacteria and fungi present in cotton do not in themselves cause byssinosis, but the endotoxins-heat-stable lipopolysaccharide-protein complexes contained in the cell wall of Gram-negative bacteria-are responsible for the development of this respiratory disease of workers on cotton, flax, and some other fibers. Experimental work was carried out in cotton fields in different cotton growing countries. Opened cotton capsules were treated by spraying them with bactericidal water solutions of benzododecinium bromide to avoid the growth of bacteria by bacteriostatic effect during transportation and storage and thus to prevent the formation of endotoxins. To simulate transport conditions, treated and nontreated cotton samples were incubated under high air humidity. The endotoxin contents were determined by Limulus amebocyte lysate assay depending on the duration of incubation. In nontreated samples the endotoxin content grew to over 5,000 ng/mg. In comparison, in treated samples the endotoxin content grew extremely slowly. Thus, the bactericidal treating of raw cotton showed high efficiency as a potential method of byssinosis prevention. The irradiation by gamma-rays is also efficient, but it is not realistic in cotton growing areas of developing countries at the present time.

The effect of parachlorophenol and camphorated parachlorophenol on nitric oxide production by a murine macrophage cell line, RAW264.7

The aim of this study was to determine the effect of parachlorophenol (PCP) and camphorated parachlorophenol (CMCP) on nitric oxide (NO) production by a murine macrophage cell line, RAW264.7. The cells were incubated on plastic disks with either PCP or CMCP. Plastic adherent and nonadherent cells were subsequently stimulated with recombinant mouse IFN-gamma or bacterial lipopolysaccharide (LPS). Nitric oxide (NO) levels detected from the culture supernatants were determined by the Griess reaction. The results showed that PCP and CMCP diluted at 10(-1) but not at 10(-3) suppressed NO production by both plastic adherent and nonadherent cells, suggesting that both phenolic compounds may suppress NO production by murine macrophages in a dose-dependent manner.