Acute pulmonary toxic effects of chlorhexidine (CHX) following an intratracheal instillation in rats

Anti-Candida activity and in vitro toxicity screening of antifungals complexed with β-cyclodextrin

The emergence of resistant fungal species and the toxicity of currently available antifungal drugs are relevant issues that require special consideration. Cyclodextrins inclusion complexes could optimize the antimicrobial activity of such drugs and create a controlled release system with few side effects. This study aimed to assess the in vitro toxicity and antifungal effectiveness of nystatin (Nys) and chlorhexidine (Chx) complexed or not with β-cyclodextrin (βCD). First, a drug toxicity screening was performed through the Artemia salina bioassay. Then, the minimum inhibitory concentrations (MICs) against Candida albicans were determined with the broth microdilution test. After MICs determination, the cytotoxicity of the drugs was evaluated through the methyl-thiazolyl-tetrazolium (MTT) and neutral red (NR) assays and through cell morphology analysis. The PROBIT analysis was used to determine the median lethal concentration (LC50), and the cell viability values were submitted to one-way analysis of variance(ANOVA)/Tukey (α = 0.05). Overall, the βCD-complexed antifungals were less toxic against A. salina than their raw forms, suggesting that inclusion complexes can reduce the toxicity of drugs. The MICs obtained were as follows: Nys 0.5 mg/L; Nys:βCD 4 mg/L; Chx 4 mg/L; and Chx:βCD 8 mg/L. Chx showed significant cytotoxicity (MTT: 12.9 ± 9.6%; NR: 10.6 ± 12.5%) and promoted important morphological changes. Cells exposed to the other drugs showed viability above 70% with no cellular damage. These results suggest that antifungals complexed with βCD might be a biocompatible option for the treatment of Candida-related infections.

Pulmonary Toxicity Assessment after a Single Intratracheal Inhalation of Chlorhexidine Aerosol in Mice

Guanidine disinfectants are important chemical agents with a broad spectrum of activity that are effective against most microorganisms. Chlorhexidine, one of the most used guanidine disinfectants, is added to shampoo and mouthwash and applied in medical device sterilization. During the use of chlorhexidine, aerosols with micron particle size may be formed, which may cause inhalation toxicity. To assess the toxicity of inhaled chlorhexidine aerosol, mice underwent the intratracheal instillation of different concentrations of chlorhexidine (0, 0.125%, 0.25%, 0.5%, and 1%) using a MicroSprayer Aerosolizer. The mice were exposed for eight weeks and then sacrificed to obtain lung tissue for subsequent experiments. Histopathology staining revealed damaged lung tissues and increased collagen exudation. At the same time, pulmonary function tests showed that chlorhexidine exposure could cause restrictive ventilatory dysfunction, consistent with pulmonary fibrosis. The results of transcriptome analyses suggest that chlorhexidine may trigger an inflammatory response and promote the activation of pathways related to extracellular matrix deposition. Further, we identified that chlorhexidine exposure might enhance mucus secretion by up-regulating Muc5b and Muc5ac genes, thereby inducing fibrosis-like injury. These findings underscore the need for standardized use of disinfectants and the assessment of their inhalation toxicity.

Harmful effects of chlorhexidine on hepatic metabolism

Chlorhexidine (CHX) is an over-the-counter antiseptic amply used by the population. There are reports that CHX acts in mitochondria as an uncoupler and inhibitor. The purpose of this study was to investigate the short-term effects of CHX on hepatic metabolic pathways linked to energy metabolism in the perfused rat liver. The compound inhibited both glucose synthesis and the urea cycle. Oxygen consumption was raised at low concentrations (up to 10 μM) and diminished at higher ones. A pronounced diminution in the cellular ATP content was observed. Conversely, CHX stimulated glycolysis and enhanced leakage of cellular enzymes (lactate dehydrogenase and fumarase). In isolated mitochondria, this antiseptic inhibited pyruvate carboxylation, oxidases, and oxygen uptake at very low concentrations (2 μM) and promoted uncoupling. The results described herein raise great concerns about the safety of CHX, as the observed effects can induce hypoglycemia, lactic acidosis, ammonemia as well as cell membrane disruption.

Discovery and Mechanistic Analysis of Structurally Diverse Inhibitors of Acetyltransferase Eis among FDA-Approved Drugs

Over one and a half million people die of tuberculosis (TB) each year. Multidrug-resistant TB infections are especially dangerous, and new drugs are needed to combat them. The high cost and complexity of drug development make repositioning of drugs that are already in clinical use for other indications a potentially time- and money-saving avenue. In this study, we identified among existing drugs five compounds: azelastine, venlafaxine, chloroquine, mefloquine, and proguanil as inhibitors of acetyltransferase Eis from Mycobacterium tuberculosis, a causative agent of TB. Eis upregulation is a cause of clinically relevant resistance of TB to kanamycin, which is inactivated by Eis-catalyzed acetylation. Crystal structures of these drugs as well as chlorhexidine in complexes with Eis showed that these inhibitors were bound in the aminoglycoside binding cavity, consistent with their established modes of inhibition with respect to kanamycin. Among three additionally synthesized compounds, a proguanil analogue, designed based on the crystal structure of the Eis-proguanil complex, was 3-fold more potent than proguanil. The crystal structures of these compounds in complexes with Eis explained their inhibitory potencies. These initial efforts in rational drug repositioning can serve as a starting point in further development of Eis inhibitors.

S, Pande A, Pandey PK. Anti-oomycete Activity of Chlorhexidine Gluconate: Molecular Docking and in vitro Studies

Saprolegniosis is one of the most catastrophic oomycete diseases of freshwater fish caused by the members of the genus Saprolegnia. The disease is responsible for huge economic losses in the aquaculture industry worldwide. Until 2002, Saprolegnia infections were effectively controlled by using malachite green. However, the drug has been banned for use in aquaculture due to its harmful effect. Therefore, it has become important to find an alternate and safe anti-oomycete agent that is effective against Saprolegnia. In this study, we investigated the anti-oomycete activity of chlorhexidine gluconate (CHG) against Saprolegnia. Before in vitro evaluation, molecular docking was carried out to explore the binding of CHG with vital proteins of Saprolegnia, such as S. parasitica host-targeting protein 1 (SpHtp1), plasma membrane ATPase, and TKL protein kinase. In silico studies revealed that CHG binds with these proteins via hydrogen bonds and hydrophobic interactions. In an in vitro study, the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of CHG against S. parasitica were found to be 50 mg/L. Further, it was tested against S. australis, another species of Saprolegnia, and the MIC and MFC were found to be 100 and 200 mg/L, respectively. At 500 mg/L of CHG, there was complete inhibition of the radial growth of Saprolegnia hyphae. In propidium iodide (PI) uptake assay, CHG treated hyphae had bright red fluorescence of PI indicating the disruption of the cell membrane. The results of the present study indicated that CHG could effectively inhibit Saprolegnia and hence can be used for controlling Saprolegniasis in cultured fish.

Should oral chlorhexidine remain in ventilator-associated pneumonia prevention bundles?

Ventilator-associated pneumonia (VAP) is related with high mortality, duration of mechanical ventilation and costs. Recent studies have questioned the safety and effectiveness of oral chlorhexidine to prevent VAP. We sought to verify whether the adverse effects of this substance outweigh its benefits. We searched several databases and selected studies that investigated the use of oral chlorhexidine and its impact on mortality. No association between oral chlorhexidine and lower VAP rates was found on meta-analyses of double-blind randomized trials, however significant increase in mortality was reported. It is speculated that chlorhexidine can cause damage to several organic sectors and cytotoxicity. Although it still can be beneficial in specific settings, robust evidence to recommend its routine application for all mechanically ventilated patients is lacking; therefore, given the possibility of harm, it would be better to follow the principle of non-maleficence until more studies becomes available.

Ventilator-Associated Events: Epidemiology, Risk Factors, and Prevention

The Centers for Disease Control and Prevention shifted the focus of safety surveillance in mechanically ventilated patients from ventilator-associated pneumonia to ventilator-associated events in 2013 to increase the objectivity and reproducibility of surveillance and to encourage quality improvement programs to focus on preventing a broader array of complications. Ventilator-associated events are associated with a doubling of the risk of dying. Prospective studies have found that minimizing sedation, increasing spontaneous awakening and breathing trials, and conservative fluid management can decrease event rates and the duration of ventilation. Multifaceted interventions to enhance these practices can decrease ventilator-associated event rates.

Should oral chlorhexidine remain in ventilator-associated pneumonia prevention bundles?

Ventilator-associated pneumonia (VAP) is related with high mortality, duration of mechanical ventilation and costs. Recent studies have questioned the safety and effectiveness of oral chlorhexidine to prevent VAP. We sought to verify whether the adverse effects of this substance outweigh its benefits. We searched several databases and selected studies that investigated the use of oral chlorhexidine and its impact on mortality. No association between oral chlorhexidine and lower VAP rates was found on meta-analyses of double-blind randomized trials, however significant increase in mortality was reported. It is speculated that chlorhexidine can cause damage to several organic sectors and cytotoxicity. Although it still can be beneficial in specific settings, robust evidence to recommend its routine application for all mechanically ventilated patients is lacking; therefore, given the possibility of harm, it would be better to follow the principle of non-maleficence until more studies becomes available.

Antiseptic mouthwash, the nitrate-nitrite-nitric oxide pathway, and hospital mortality: a hypothesis generating review

Meta-analyses and several large cohort studies have demonstrated that antiseptic mouthwashes are associated with mortality in hospitalized patients. A clear pathogenic mechanism is lacking, leading to controversy and a reluctance to abandon or limit the use of antiseptic mouthwashes. Here, we generate the hypothesis that a disturbance in nitric oxide homeostasis by antiseptic mouthwashes may be responsible for the observed increase in mortality risk. Nitric oxide is essential in multiple physiological processes, and a reduction in nitric oxide bioavailability is associated with the occurrence or worsening of pathologies, such as atherosclerosis, diabetes, and sepsis. Oral facultative anaerobic bacteria are essential for the enterosalivary nitrate–nitrite–nitric oxide pathway due to their capacity to reduce nitrate to nitrite. Nitrate originates from dietary sources or from the active uptake by salivary glands of circulating nitrate, which is then excreted in the saliva. Because antiseptic mouthwashes eradicate the oral bacterial flora, this nitric oxide-generating pathway is abolished, which may result in nitric oxide-deficient conditions potentially leading to life-threatening complications such as ischaemic heart events or sepsis.

Oropharyngeal antisepsis in the critical patient and in the patient subjected to mechanical ventilation

Lower respiratory tract infections in the intubated patient constitute a serious health problem due to their associated morbidity and mortality. Microaspiration of the buccopharyngeal secretions is the main physiopathological mechanism underlying the development of pneumonia and tracheobronchitis in intubated patients. All care bundles designed to prevent these infections include the use of antiseptics to reduce buccopharyngeal colonization. Chlorhexidine is the antiseptic most frequently assessed in clinical trials and meta-analyses that conclude that oral hygiene with chlorhexidine reduces the incidence of ventilator-associated pneumonia - maximum effectiveness being achieved when the product is administered at a concentration of 2%. However, 2meta-analyses have warned of a possible increase in mortality when chlorhexidine is used as an oral antiseptic. We therefore recommend its use but with extreme caution during application in order to avoid aspiration of the antiseptic. This article is part of a supplement entitled "Antisepsis in the critical patient", which is sponsored by Becton Dickinson.

Effects of chlorhexidine gluconate oral care on hospital mortality: a hospital-wide, observational cohort study

Purpose

Chlorhexidine oral care is widely used in critically and non-critically ill hospitalized patients to maintain oral health. We investigated the effect of chlorhexidine oral care on mortality in a general hospitalized population.

Methods

In this single-center, retrospective, hospital-wide, observational cohort study we included adult hospitalized patients (2012–2014). Mortality associated with chlorhexidine oral care was assessed by logistic regression analysis. A threshold cumulative dose of 300 mg served as a dichotomic proxy for chlorhexidine exposure. We adjusted for demographics, diagnostic category, and risk of mortality expressed in four categories (minor, moderate, major, and extreme).

Results

The study cohort included 82,274 patients of which 11,133 (14%) received chlorhexidine oral care. Low-level exposure to chlorhexidine oral care (≤ 300 mg) was associated with increased risk of death [odds ratio (OR) 2.61; 95% confidence interval (CI) 2.32–2.92]. This association was stronger among patients with a lower risk of death: OR 5.50 (95% CI 4.51–6.71) with minor/moderate risk, OR 2.33 (95% CI 1.96–2.78) with a major risk, and a not significant OR 1.13 (95% CI 0.90–1.41) with an extreme risk of mortality. Similar observations were made for high-level exposure (> 300 mg). No harmful effect was observed in ventilated and non-ventilated ICU patients. Increased risk of death was observed in patients who did not receive mechanical ventilation and were not admitted to ICUs. The adjusted number of patients needed to be exposed to result in one additional fatality case was 47.1 (95% CI 45.2–49.1).

Conclusions

These data argue against the indiscriminate widespread use of chlorhexidine oral care in hospitalized patients, in the absence of proven benefit in specific populations.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5171-3) contains supplementary material, which is available to authorized users.

Ventilator-Associated Events and Their Prevention

The Centers for Disease Control and Prevention shifted the focus of safety surveillance in mechanically ventilated patients from ventilator-associated pneumonia to ventilator-associated events (VAEs) in 2013. The shift was designed to increase the objectivity and reproducibility of surveillance and to encourage quality-improvement programs to tackle a broader array of complications in mechanically ventilated patients. Prospective intervention studies have found that minimizing sedation, increasing the use of spontaneous awakening and breathing trials, and conservative fluid management can lower VAE rates and decrease duration of mechanical ventilation. Additional strategies to prevent VAEs include early mobility programs, low tidal volume ventilation, and restrictive transfusion thresholds.

Leakage of fluid around endotracheal tube cuffs: a cadaver study

Background

The aim of the study was to evaluate the leakage of liquid past the cuffs of tracheal tubes in fresh frozen human heads.

Methods

Six truncated fresh frozen heads were used and intubated with 8.0 mm endotracheal tubes. The intracuff pressures tested were 30 and 100 cmH₂O. Subsequently, 20 ml of each of two oral antiseptic rinses (0.2% chlorhexidine and octenidine [octenidol®, Schülke & Mayr GmbH, Norderstedt, Germany]) was applied for thirty seconds in the mouth. During the trial, leakage of the cuffs was examined.

Results

The sealing between the tracheal cuff and tracheal wall was leakage-proof for all tested intracuff pressures and all tested antiseptic rinses. However, approximately 5.6 ml and 1.8 ml leaked into the esophagus and remained as a cuff-puddle, respectively.

Conclusions

The sealing between an endotracheal tube cuff with an intracuff pressure of 30 cmH₂O and the tracheal wall is leakage-proof during oral care with antiseptic rinsing. An increase of intracuff pressure to 100 cmH₂O does not appear to be required.

Assessment of cytogenetic and cytotoxic effects of chlorhexidine digluconate on cultured human lymphocytes

OBJECTIVE

The aim of this study was to assess the genetic and cellular toxicity of Chlorhexidine digluconate (CHX) on peripheral human lymphocytes in vitro.

MATERIALS AND METHODS

Micronucleus assay was used to investigate the genotoxicity, while the cell viability and proliferation were evaluated by Trypan blue exclusion test and Nuclear Division Index in control and CHX-treated (0.05, 0.1, 0.2, 0.4, 0.5 mg/ml) human blood cultures.

RESULTS

A dose-dependent toxic effect was found depending on CHX incubation on the genetic and cell viability of the lymphocytes. Micronucleus frequency was found to be statistically higher at 0.5 mg/ml concentration compared to lower doses and the control group (p < 0.05). A significant reduction was shown in the cell viability and cell proliferation of the exposed lymphocytes at the concentrations of 0.4 and 0.5 mg/ml (p < 0.05), while no significant toxicity was found at lower concentrations compared to control (p > 0.05).

CONCLUSION

This study showed dose-dependent genotoxic and cytotoxic effects of CHX on human lymphocytes in vitro. It should be considered during periodontal irrigation or novel CHX products at lower concentrations should be manufactured for clinical usage.