Bismuth salts and neurotoxicity. A randomised, single-blind and controlled study

In vitro evaluation of the antibacterial effect of colloidal bismuth subcitrate on Porphyromonas gingivalis and its biofilm

OBJECTIVE

To investigate the antibacterial and anti-biofilm effects of colloidal bismuth subcitrate (CBS) on Porphyromonas gingivalis (P. gingivalis) in its planktonic and biofilm forms and also compare it with that of 0.2% chlorhexidine (CHX).

DESIGN

The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CBS were determined by the microdilution method; the bacteriostatic rate of CBS was determined by the MTT assay; the effect of CBS on the membrane integrity of P. gingivalis was investigated by the flow cytometric methods. The effects of CBS on the biomass and bacterial activity of biofilm were investigated. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were used to investigate the activity and structure of biofilms.

RESULTS

The MIC and MBC values were 18.75 µg/mL and 37.5 µg/mL. CBS could damage the cell membrane of P. gingivalis. CBS effectively inhibited biofilm formation and promoted dissociation at higher concentrations of 37.5 µg/mL and 75 µg/mL, respectively. The results also indicated an altered biofilm structure and reduced biofilm thickness and bacterial aggregation.

CONCLUSIONS

CBS affected the metabolic and physiological processes of P. gingivalis, inhibited the formation of biofilm, and disrupted the mature biofilm.

Systematic Review and Meta-Analyses Assessment of the Clinical Efficacy of Bismuth Subsalicylate for Prevention and Treatment of Infectious Diarrhea

BACKGROUND

A large number of studies have evaluated the pharmacology, safety, and/or efficacy of bismuth subsalicylate for the relief of common gastrointestinal symptoms, diarrhea and vomiting due to acute gastroenteritis. In addition, short-term (48 h) medication with bismuth subsalicylate is known to be effective against infectious gastroenteritis such as travelers' diarrhea.

AIMS

Previous studies have documented the bacteriostatic/bactericidal effects of bismuth subsalicylate against a variety of pathogenic gastrointestinal bacteria. However, meta-analyses of the clinical efficacy of bismuth subsalicylate for both prevention and treatment of travelers' diarrhea have not yet been published.

METHODS

A total of 14 clinical studies (from 1970s to 2007) comprised the core data used in this assessment of efficacy of bismuth subsalicylate against infectious (including travelers') diarrhea. These studies allowed for statistical meta-analyses regarding prevention (three travelers' diarrhea studies) and treatment of infectious diarrhea (11 studies [five travelers' diarrhea]).

RESULTS

The results show that subjects treated with bismuth subsalicylate for up to 21 days have 3.5 times greater odds of preventing travelers' diarrhea compared with placebo (95% CI 2.1, 5.9; p < 0.001). In addition, subjects with infectious diarrhea treated with bismuth subsalicylate had 3.7 times greater odds of diarrhea relief (recorded on diaries as subjective symptomatic improvement) compared to those receiving placebo (95% CI 2.1, 6.3; p < 0.001).

CONCLUSIONS

This systematic review and meta-analysis suggests that bismuth subsalicylate can be beneficial for those at risk or affected by food and waterborne diarrheal disease such as traveler's (infectious) diarrhea, and may decrease the risk of inappropriate antibiotic utilization.

Bismuth Concentrations in Patients Treated in Real-Life Practice with a Bismuth Subcitrate-Metronidazole-Tetracycline Preparation: The SAPHARY Study

INTRODUCTION

A fixed-dose association of bismuth subcitrate, metronidazole and tetracycline (BMT) (Pylera^®, Allergan, NJ, USA) was made available in France in 2013 for the eradication of Helicobacter pylori. Due to a historical issue of bismuth encephalopathy, the French Health Authorities requested a study of blood and plasma bismuth concentrations with BMT in daily practice.

AIMS

The aim of the study was to measure eventual bismuth accumulation and neurological toxicity in patients prescribed BMT.

METHODS

Patients initiating BMT for H. pylori between March 2014 and December 2015 were included. A blood sample was taken before first BMT intake and 24 h after the last intake, for assay of bismuth. A concentration > 50 μg/L was considered abnormal. Neurological complaints were assessed at inclusion, at the end of the 10-day treatment course, and 28 days later.

RESULTS

202 patients were included, of whom 190 took at least one dose of BMT, and 167 provided both required blood samples. Mean blood bismuth concentrations after the BMT course were 16.9 μg/L (95% confidence interval 15.6-18.3). Concentrations were > 50 μg/L (56.0 μg/L and 50.9 μg/L) in two elderly patients, one of whom presented mild, transient memory impairment during treatment. Non-serious neurological symptoms occurred in 20% of all patients and treatment failure was documented in 5% of patients.

CONCLUSIONS

In this study measuring blood bismuth concentrations in real-life practice, in < 1% of patients the BMT course resulted in blood bismuth concentrations > 50 μg/L. No serious neurological adverse events were observed.

STUDY REGISTRATION

EU-PAS register EUPAS3142 at www.encepp.eu ; ENCePP study seal.

Comparison of three different regimens against Helicobacter pylori as a first-line treatment: A randomized clinical trial

Treatments with bismuth-containing quadruple therapy (QT), sequential therapy (ST), or concomitant therapy (CT) have been proposed as empirical first-line regimens for Helicobacter pylori. We compared the efficacy and tolerability of 10 days bismuth-containing quadruple QT, 10 days ST, and 10 days CT with as first-line treatments for H. pylori in a randomized crossover study. The subjects were randomly divided into three groups. The first 130 patients were treated with rabeprazole, bismuth potassium citrate, metronidazole, and tetracycline for 10 days. The second 130 patients in the sequential group were treated with rabeprazole and amoxicillin for 5 days, and then rabeprazole, clarithromycin, and metronidazole for an additional 5 days. The last 130 patients in the concomitant group were treated with rabeprazole, amoxicillin, clarithromycin, and metronidazole for 10 days. H. pylori eradication was confirmed by urea breath test at 6 weeks. The primary outcome was eradication rates of first-line treatment by intention to treat and per protocol (PP) analyzes. There was no difference between the average ages and the male/female ratio of the groups. The PP analysis was performed on 121, 119, and 118 patients in the QT, ST, and CT groups, respectively. In the PP analysis, the successful eradication 94.2% (114/121), 95.0% (113/119), and 95.8% (113/118) the QT, ST, and CT groups, respectively. There was no significant difference among the three groups (p = 0.86). 10 days QT, ST, and CT are highly effective as empirical first-line therapies for H. pylori in the region with high clarithromycin resistance.

Review: clinical management of Helicobacter pylori infection in China

Helicobacter pylori (H. pylori) infection has been associated with gastric disorders. The situation of H. pylori infection in China-where a high prevalence of H. pylori infection, a high incidence of gastric cancer, and widespread resistance to clarithromycin, metronidazole, and levofloxacin exist-is quite different from that in Western countries. In order for Chinese clinicians to better manage H. pylori infection, a Chinese Study Group on H. pylori published four consensus reports regarding the management of H. pylori infection in China between 1999 and 2012. The eradication rate with standard triple therapy was <80% in most areas of China. Bismuth is available in China, and bismuth-containing quadruple therapy has been shown to produce a high eradication rate; thus, bismuth quadruple therapy could be recommended both as an initial and as a rescue therapy in China. There is no advantage of sequential therapy over triple therapy in Chinese patients, but the efficacy of concomitant therapy must be studied further. This review introduces the epidemiology, diagnosis, indicators, and therapies for the eradication of H. pylori in China in recent years.

Production of toxic volatile trimethylbismuth by the intestinal microbiota of mice

The biotransformation of metals and metalloids into their volatile methylated derivatives by microbes growing under anaerobic conditions (e.g., the mammalian intestinal microbiota) plays an important role in spreading these compounds in the environment. In this paper, we could show that the presence of an intact intestinal microbiota of mice provides the conditio sine qua non for the production of these mostly toxic derivatives. To document the indispensible role of the intestinal microbiota in methylating metals and metalloids to volatile derivatives under in vivo conditions, we compared the methylation capability of conventionally raised (CONV) and germ-free (GF) B6-mice fed with chow containing colloidal bismuth subcitrate (CBS) as the starting material for the formation of volatile methylated metal(loid)s. Permethylated volatile trimethylbismuth ((CH(3))(3)Bi) was only detected in the blood of the conventionally raised mice. Concomitantly, a higher bismuth concentration was found in organs such as liver, lung, testicles, and brain of the CONV mice as compared to those of GF mice (P > 0.01), strongly suggesting a correlation between the intestinal biomethylation of bismuth and its accumulation in mammalian tissues.

Bismuth coating of non-tunneled haemodialysis catheters reduces bacterial colonization: a randomized controlled trial

BACKGROUND

Haemodialysis (HD) catheter-related blood stream infections are a major cause of morbidity and mortality in patients with acute and chronic renal failure.

METHODS

We conducted a randomized, prospective, double-blinded trial investigating the clinical value of bismuth-coated non-tunneled HD catheters in patients in need of temporary short-term vascular access. A standard catheter (SC) was compared to a surface-modified, bismuth-film-coated catheter (FCC). After removal of the catheter for any reason, both arterial and venous lumina were rinsed and the fluid cultured for detection of bacterial colony-forming units (CFU). The catheter tip was placed in a tube containing sterile saline, sonicated and shortly centrifuged to remove debris (3 min at 1000 g). The supernatant was cultured and assayed for DNA content.

RESULTS

Seventy-seven patients in three HD units were randomized. Thirteen patients suffered from acute renal failure, 60 patients from chronic renal failure, and four patients without renal insufficiency were treated with plasma exchange. The time to catheter removal was not significantly different between groups, with a mean of 18.5 +/- 2 days for SC and 15.1 +/- 2 days for FCC. In most cases, the reasons for catheter removal were related to no further need for extracorporeal therapy or establishment of a permanent vascular access. Six catheters for SC and four catheters for FCC were removed because of presumed infection. Bacterial colonization was significantly lower for coated catheters compared to standard catheters, both for cultured catheter tips as well as for CFU in rinse fluids (P < 0.05).

CONCLUSIONS

Surface modification with bismuth film reduces bacterial colonization of temporary non-tunneled HD catheters in a clinical trial. Larger trials with these modified catheters are justified to further investigate the effect on catheter-related infections, complications and costs.

Role of intestinal microbiota in transformation of bismuth and other metals and metalloids into volatile methyl and hydride derivatives in humans and mice

The present study shows that feces samples of 14 human volunteers and isolated gut segments of mice (small intestine, cecum, and large intestine) are able to transform metals and metalloids into volatile derivatives ex situ during anaerobic incubation at 37 degrees C and neutral pH. Human feces and the gut of mice exhibit highly productive mechanisms for the formation of the toxic volatile derivative trimethylbismuth [(CH(3))(3)Bi] at rather low concentrations of bismuth (0.2 to 1 mumol kg(-1) [dry weight]). An increase of bismuth up to 2 to 14 mmol kg(-1) (dry weight) upon a single (human volunteers) or continuous (mouse study) administration of colloidal bismuth subcitrate resulted in an average increase of the derivatization rate from approximately 4 pmol h(-1) kg(-1) (dry weight) to 2,100 pmol h(-1) kg(-1) (dry weight) in human feces samples and from approximately 5 pmol h(-1) kg(-1) (dry weight) to 120 pmol h(-1) kg(-1) (dry weight) in mouse gut samples, respectively. The upshift of the bismuth content also led to an increase of derivatives of other elements (such as arsenic, antimony, and lead in human feces or tellurium and lead in the murine large intestine). The assumption that the gut microbiota plays a dominant role for these transformation processes, as indicated by the production of volatile derivatives of various elements in feces samples, is supported by the observation that the gut segments of germfree mice are unable to transform administered bismuth to (CH(3))(3)Bi.

Acute renal failure after overdose of colloidal bismuth subcitrate

Bismuth salts are widely used to treat peptic ulcers. Acute toxicity with colloidal bismuth subcitrate overdose causes nephrotoxicity. There have been numerous reports of encephalopathy after long-term consumption of bismuth salts, but only a few cases of nephrotoxicity (adult and pediatric) have been documented to date. This report presents a case of acute renal failure due to colloidal bismuth subcitrate overdose in adolescent. A 16-year-old girl presented with complaints of nausea, vomiting, and facial paresthesia. Ten days earlier she had tried to commit suicide by taking 60 tablets of De-nol (colloidal bismuth subcitrate 18 g). The physical examination findings on admission indicated minimal fluid overload but no signs of encephalopathy. Laboratory tests on admission showed blood urea nitrogen 102 mg/dl, serum creatinine 19.9 mg/dl, and serum bismuth level 495 microg/l. The patient was started on appropriate fluid therapy and penicillamine as a chelating agent and then began hemodialysis on alternate days. The patient's renal function gradually returned to normal over 9 weeks and by 64 days after the overdose her serum bismuth level had fallen to almost half the level detected 2 days after admission. The patient made a complete recovery. The case demonstrates that acute renal failure can develop as a manifestation of acute toxicity from colloidal bismuth ingestion, and that the prognosis may be favorable if the patient receives appropriate supportive treatment and dialysis.

Binding of bismuth to serum proteins: implication for targets of Bi(III) in blood plasma

Bismuth complexes have been widely used in clinical treatment as antiulcer drugs. However, different adverse effects have been observed and the diagnosis is generally confirmed by the detection of bismuth in blood or blood plasma. In this study, binding of bismuth to human serum albumin was studied by fluorescence spectroscopy with the binding constant logK(a) to be 11.2. Competitive binding of bismuth to human albumin and transferrin was carried out at pH 7.4 by FPLC and ICP-MS. It was found that over 70% of bismuth binds to transferrin even in the presence of a large excess of albumin (albumin/transferrin=13:1) at pH 7.4, 10 mM bicarbonate. The distribution of bismuth between the two proteins was almost unchanged when Cys(34) of albumin was blocked. However, all bismuth binds to albumin when iron-saturated transferrin was used. Almost all of the bismuth was distributed over the fractions containing transferrin (70%) and albumin (<30%) in serum. The percentage of bismuth associated with transferrin was further increased by 15% with elevated transferrin in serum. Binding of bismuth to transferrin is much stronger than human albumin. Transferrin is probably the major target of bismuth in blood plasma, and it may play a role in the pharmacology of bismuth.