Metronidazole-induced encephalopathy: not always a reversible situation

Potential Role of Therapeutic Drug Monitoring in Preventing Antibiotic-Induced Neuropsychiatric Disorders: A Narrative Review

BACKGROUND

Neuropsychiatric toxicity is a common adverse effect of antibiotics. Advanced age, renal insufficiency, high drug doses, and prolonged therapy are relevant risk factors, suggesting that this event might be caused due to the accumulation of antibiotics in the central nervous system. In this review, the authors aimed to evaluate the potential role of therapeutic drug monitoring in identifying patients at risk of antibiotic-induced neuropsychiatric toxicity.

METHODS

A MEDLINE PubMed search was conducted for articles published between January 1990 and December 2024, matching the terms "pharmacokinetics" or "therapeutic drug monitoring" with "antibiotics" (including individual drug classes) and "neurotoxicity" (including synonyms). Additional studies were identified from the reference lists of retrieved articles.

RESULTS

Significant associations have been reported between plasma concentrations of some beta-lactam antibiotics (ceftazidime, cefepime, piperacillin, and meropenem) or linezolid and drug-induced central nervous system adverse events (such as seizures, encephalopathy, peripheral neuropathy, and optic neuropathy). Safety thresholds of plasma concentrations have been proposed for these drugs.

CONCLUSIONS

Consistent data on the associations between plasma drug concentrations and neuropsychiatric disorders are available only for some antibiotics, whereas for others, there are few and often inconsistent data, hindering the establishment of therapeutic drug monitoring-based safety thresholds for these antibiotics.

Frequency and Risk Factor Analysis for Metronidazole-Associated Neurologic Adverse Events

BACKGROUND

Little is known about the risk factors and frequency of metronidazole-associated neurological adverse events.

OBJECTIVE

To investigate the risk factors and frequency of metronidazole-associated neurological adverse events.

DESIGN

This retrospective study contained two parts. First, we investigated metronidazole treatment-associated neurologic adverse events by performing a population-based cohort study using the Korea Adverse Event Reporting System (KAERS) database from January 2011 to December 2020. Second, we conducted a matched case-control study based on a retrospective cohort of patients treated with metronidazole between January 2006 and July 2021 at a tertiary hospital in South Korea. The data analysis was performed from August 2021 to April 2022.

PARTICIPANTS

In the case-control study, case patients were defined as those diagnosed with metronidazole-associated encephalopathy or peripheral neuropathy during the study period with causal assessment based on the clinical diagnoses and findings from associated tests. In a ratio of 1:3, case patients were compared to a control group of patients prescribed metronidazole without neurologic adverse events matched for age and cumulative dose of metronidazole.

MAIN MEASURES

Frequency and risk factors for metronidazole-associated neurological adverse events.

KEY RESULTS

Overall, 2,309 cases of neurologic adverse events were reported to the KAERS from 2011 to 2020, and the number of reported neurological adverse events showed an increasing trend. Further, 92,838 patients were prescribed metronidazole during the study period at the Severance Hospital; 54 patients were diagnosed with metronidazole-associated encephalopathy or peripheral neuropathy, 40 with central and 28 with peripheral nervous system adverse events. Liver cirrhosis, chronic kidney disease, intravenous administration, and lower body weight were identified as risk factors for these adverse events.

CONCLUSIONS

The number of reported metronidazole-associated neurological adverse events are increasing. Prolonged metronidazole treatment in patients with the aforementioned factors requires careful examination for neurological adverse events.

Metronidazole-Induced Acute Cerebellitis in a Young Patient: Unusual Onset, Delayed Remission, and Characteristic Imaging Features

Metronidazole-induced acute cerebellitis is an exceptionally rare condition resulting from severe adverse reactions to metronidazole, a medication generally employed in the management of infections caused by anaerobic microbes. Although neuropathy has been linked to metronidazole use, reports of acute cerebellitis are infrequent. The neurological effects associated with metronidazole can include weakness, dysarthria, postural instability, seizures, giddiness, vertigo, ataxia, confusion, encephalopathy, headaches, and tremors. The onset of cerebellitis can vary, occurring as early as one day or after several weeks of metronidazole treatment. This article presents a case of a young girl who presented to us with weakness in both upper and lower limbs, dysarthria, and postural instability after exposure to 12 grams of metronidazole (suicidal, 30 tablets of 400 mg). With the above-mentioned complaints, the patient was advised of magnetic resonance imaging of the brain, which showed the features of cerebellitis.

Metronidazole promotes oxidative stress and DNA fragmentation-mediated myocardial injury in albino mice

The purpose of the present study was to investigate the cardiotoxic effects of Metronidazole (Mtz) in albino mice. The mice were divided into four experimental groups: Gp.I (control group): saline, Gp.II:125 mg/kg b.w Mtz, Gp.III:250 mg/kg b.w, Gp.IV:500 mg/kg b.w Mtz. Heart weight ratio, markers of cardiac injury, markers of oxidative stress, histopathological examinations, DNA fragmentation and spectral analysis were used to determine cardiotoxicity. Administration of 125-500 mg/kg Mtz caused an increase in heart weight and a decrease in body weight. Administration of 500 mg/kg Mtz increased heart weight by 35.5% and decreased body weight by 21.9% compared with control. Mtz-treated mice showed a significant increase in cardiac injury biomarkers and serious alterations in cardiac oxidative stress markers. Histopathological changes of cardiac tissues observed in mice treated with Mtz include myocardial hypertrophy, fibrosis, myocarditis, separation of the muscle fibers, congestion-narrowing in vessels, necrosis, myocardium-vacuolation, myocytolysis, myocyte degeneration, nuclear aggregation, cytoplasmic fragmentation and prevalent nuclei. Mtz treatment already resulted in a significant decrease in the percentage of head DNA and an increase in the percentage of tail DNA. The most striking tail formation among the Mtz-treated groups was observed in the group receiving 500 mg/kg Mtz. In the presence of Mtz, there was a hypochromic shift in the absorption spectrum of DNA, and the potential DNA-Mtz interaction was found to occur in the intercalation mode. These results show that Mtz used against anaerobic bacteria and protozoa in gastrointestinal infections can cause severe cardiotoxic findings in albino mice and cause fragmentation in DNA.

Metronidazole-induced encephalopathy delayed diagnosis due to cerebellar infarction: A case report

RATIONALE

Metronidazole is a 5-nitroimidazole antibiotic effective against anaerobic bacterial and parasitic infections. Long-term use may cause side effects in the central nervous system, although the occurrence of encephalopathy is rare.

PATIENT CONCERNS

A 73-year-old man was diagnosed with acute pyelonephritis and received antibiotic treatment. During the treatment, the patient complained of back pain. Lumbar spinal magnetic resonance imaging (MRI) revealed infective spondylitis, and metronidazole (1.5 g) was administered daily for approximately 160 days. The patient developed cognitive dysfunction and gait disorder after antibiotic treatment, and brain MRI showed acute infarction in both cerebellar lobes. Secondary prevention with antiplatelet and physiotherapy was prescribed; however, functional recovery was not achieved.

DIAGNOSIS

After 1 month, a follow-up brain MRI showed high signal intensity and diffusion restriction in the corpus callosum on diffusion-weighted images and high signal intensity in the dentate nucleus on T2-weighted images. Therefore, metronidazole-induced encephalopathy was suspected.

INTERVENTIONS

Metronidazole was discontinued, and ceftriaxone (2 g/day) was administered to manage the infective spondylitis.

OUTCOMES

One week after the discontinuation of the drug, the patient's cognition improved to the extent that communication was possible. Thus, even if other neurological deficits, such as cerebellar infarction, are found in patients with long-term disability, the possibility of metronidazole-induced encephalopathy should be considered when metronidazole is used for a long time.

Metronidazole induced cerebellar toxicity after prolonged treatment of large multiloculated pyogenic liver abscess; A case report and literature review

Metronidazole is a common antibiotic agent for hepatic abscesses, which require both gram-negative and anaerobic coverage. Rarely, this antibiotic has been found to induce encephalopathy. Here, we describe a 65-year-old male who was treated with metronidazole for his hepatic abscess, who presented with syncope and questionable seizure and was found to have magnetic resonance imaging (MRI) brain findings consistent with metronidazole toxicity. Our patient demonstrated striking brain MRI findings which can be used to further understand the process behind this medication-induced toxicity. Hypotheses of this mechanism include swelling of axons secondary to increased water or vasospasm leading to reversible ischemia that is localized in the brain. In terms of MRI findings, brain lesions tend to populate bilaterally with focus at the dorsal pons, midbrain, cerebellar dentate nuclei (as with our patient), dorsal medulla, or splenium of corpus callosum. Additional research is warranted regarding this rare manifestation and timely removal of the offending agent is crucial for reversal of symptoms.

S, Siddiqui SA, Gupta A, Pathak V, Mulani M, Khan S, Bansal T. MRI Findings and Topographic Distribution of Lesions in Metronidazole-Induced Encephalopathy

Purpose

This study aims to describe the magnetic resonance imaging (MRI) of the brain of five patients diagnosed with metronidazole-induced encephalopathy (MIE). In addition, the aim of our study was to better define the topographic distribution of lesions in MIE.

Methods

We retrospectively evaluated MRI findings before and after drug cessation in five patients diagnosed with MIE at Era’s Lucknow Medical College and Hospital, Lucknow, Uttar Pradesh, India. The main MRI signal changes and lesion locations were studied.

Results

Among the patients observed, the average age of the patients with MIE was 55 years (range: 30-70 years). Cerebellar dysfunction, mainly ataxia, and altered mental status were seen in the majority of cases. The most frequently involved sites were the dentate nucleus (cerebellum), brain stem, and corpus callosum (splenium). In diffusion-weighted imaging (DWI), most lesions did not show true restricted diffusion, except for a solitary corpus callosum lesion.

Conclusion

Although drug-related side effects are more common with long-term use of metronidazole, they may also occur with high doses for short durations. The dentate nucleus, the splenium in the corpus callosum, and the brain stem are the most affected structures. Apart from a solitary lesion of the corpus callosum, all identified lesions were reversible at follow-up MRI after discontinuation of metronidazole. The clinical presentation and characteristic MRI changes are highly specific and can be correlated to make a rapid and more accurate diagnosis of this potentially treatable condition. Prognosis is excellent if detected early.

Antibiotics and the Nervous System-Which Face of Antibiotic Therapy Is Real, Dr. Jekyll (Neurotoxicity) or Mr. Hyde (Neuroprotection)?

Antibiotics as antibacterial drugs have saved many lives, but have also become a victim of their own success. Their widespread abuse reduces their anti-infective effectiveness and causes the development of bacterial resistance. Moreover, irrational antibiotic therapy contributes to gastrointestinal dysbiosis, that increases the risk of the development of many diseases, including neurological and psychiatric. One of the potential options for restoring homeostasis is the use of oral antibiotics that are poorly absorbed from the gastrointestinal tract (e.g., rifaximin alfa). Thus, antibiotic therapy may exert neurological or psychiatric adverse drug reactions which are often considered to be overlooked and undervalued issues. Drug-induced neurotoxicity is mostly observed after beta-lactams and quinolones. Penicillin may produce a wide range of neurological dysfunctions, including encephalopathy, behavioral changes, myoclonus or seizures. Their pathomechanism results from the disturbances of gamma-aminobutyric acid-GABA transmission (due to the molecular similarities between the structure of the β-lactam ring and GABA molecule) and impairment of the functioning of benzodiazepine receptors (BZD). However, on the other hand, antibiotics have also been studied for their neuroprotective properties in the treatment of neurodegenerative and neuroinflammatory processes (e.g., Alzheimer's or Parkinson's diseases). Antibiotics may, therefore, become promising elements of multi-targeted therapy for these entities.

Metronidazole, an Uncommon Cause of Dizziness and Ataxia in the Emergency Department: A Case Report

Introduction

Metronidazole, a nitroimidazole antibiotic, is a well-known antibacterial and antiprotozoal agent that is generally well tolerated without many serious side effects. Most adverse reactions affect the gastrointestinal or genitourinary system, but the central nervous system may also be afflicted. In addition to headache and dizziness, cerebellar dysfunction can occur with metronidazole use.

Case Report

We discuss the clinical presentation and imaging findings of metronidazole-induced encephalopathy in a 12-year-old male. The patient had a history of Crohn’s disease and chronic Clostridium difficile infection for which he had received metronidazole for approximately 75 days prior to arrival to a local emergency department (ED). He presented with five days of progressive vertigo, nausea, vomiting, and ataxia. Subsequent magnetic resonance imaging showed symmetric hyperintense dentate nuclei lesions, characteristic of metronidazole-induced encephalopathy. The patient’s symptoms improved rapidly after cessation of metronidazole, and his symptoms had completely resolved by discharge on hospital day two.

Conclusion

Metronidazole-induced encephalopathy is a rare cause of vertigo and ataxia that can lead to permanent sequela if not identified and treated promptly. Thus, it is important for physicians to keep this diagnosis in mind when evaluating patients on metronidazole who present to the ED with new neurologic complaints.

Pediatric Metronidazole-Induced Encephalopathy: A Case Report and Review of the Literature

Metronidazole-induced encephalopathy is a rare toxic encephalopathy secondary to the common use to this antimicrobial drug. It has been reported mainly in adult patients but only rarely in children. Owing to possible devastating complication of this disease, clinicians should have a higher index of suspicion for encephalopathic patients on metronidazole therapy. Here, we report a 5-month-old infant with metronidazole-induced encephalopathy presenting with nonconvulsive status epilepticus. A review of the literature in pediatric, as well as adult metronidazole-induced encephalopathy, is also provided.

Anti-Giardia Drug Discovery: Current Status and Gut Feelings

Giardia parasites are ubiquitous protozoans of global importance that impact a wide range of animals including humans. They are the most common enteric pathogen of cats and dogs in developed countries and infect ∼1 billion people worldwide. While Giardia infections can be asymptomatic, they often result in severe and chronic diseases. There is also mounting evidence that they are linked to postinfection disorders. Despite growing evidence of the widespread morbidity associated with Giardia infections, current treatment options are limited to compound classes with broad antimicrobial activity. Frontline anti-Giardia drugs are also associated with increasing drug resistance and treatment failures. To improve the health and well-being of millions, new selective anti-Giardia drugs are needed alongside improved health education initiatives. Here we discuss current treatment options together with recent advances and gaps in drug discovery. We also propose criteria to guide the discovery of new anti-Giardia compounds.

Antibiotic-induced epileptic seizures: mechanisms of action and clinical considerations

In recent years, there has been growing interest in the development of epileptic seizures as an adverse effect of antibiotic therapy. The most commonly accepted mechanisms underlying the development of antibiotic-induced seizures include direct- and indirect gamma-aminobutyric acid (GABA) antagonism, inhibition of GABA synthesis, and glutaminergic N-methyl-D-Aspartate (NMDA) receptor agonistic activity. Inhibitory pathway inhibition leads to increased neuronal excitability and lowered seizure threshold. Blockage of myoneural presynaptic acetylcholine release, mitochondrial dysfunction, interference of neural protein synthesis, and oxidative stress caused by the generation of neurotoxic radicals also contributes to the development of neurotoxicity. Patients with pre-existing risk factors such as renal or hepatic insufficiency, central nervous system pathology, neurological diseases, history of epilepsy or seizures, critical illness, and increased age are more susceptible to seizure development as a consequence of antibiotic therapy. Administration of antibiotics, together with antiseizure drugs, may also lead to enhanced seizure risk due to drug interactions, which predisposes to alterations in drug metabolism and therapeutic efficacy.

Click chemistry-facilitated comprehensive identification of proteins adducted by antimicrobial 5-nitroimidazoles for discovery of alternative drug targets against giardiasis

Giardiasis and other protozoan infections are major worldwide causes of morbidity and mortality, yet development of new antimicrobial agents with improved efficacy and ability to override increasingly common drug resistance remains a major challenge. Antimicrobial drug development typically proceeds by broad functional screens of large chemical libraries or hypothesis-driven exploration of single microbial targets, but both strategies have challenges that have limited the introduction of new antimicrobials. Here, we describe an alternative drug development strategy that identifies a sufficient but manageable number of promising targets, while reducing the risk of pursuing targets of unproven value. The strategy is based on defining and exploiting the incompletely understood adduction targets of 5-nitroimidazoles, which are proven antimicrobials against a wide range of anaerobic protozoan and bacterial pathogens. Comprehensive adductome analysis by modified click chemistry and multi-dimensional proteomics were applied to the model pathogen Giardia lamblia to identify dozens of adducted protein targets common to both 5'-nitroimidazole-sensitive and -resistant cells. The list was highly enriched for known targets in G. lamblia, including arginine deiminase, α-tubulin, carbamate kinase, and heat shock protein 90, demonstrating the utility of the approach. Importantly, over twenty potential novel drug targets were identified. Inhibitors of two representative new targets, NADP-specific glutamate dehydrogenase and peroxiredoxin, were found to have significant antigiardial activity. Furthermore, all the identified targets remained available in resistant cells, since giardicidal activity of the respective inhibitors was not impacted by resistance to 5'-nitroimidazoles. These results demonstrate that the combined use of click chemistry and proteomics has the potential to reveal alternative drug targets for overcoming antimicrobial drug resistance in protozoan parasites.

Metronidazole Encephalopathy EEG Features: A Case Report with Systematic Review of the Literature

Metronidazole-induced encephalopathy (MIE) is a rare and often under-recognized iatrogenic condition. The diagnosis should be considered in metronidazole-treated patients presenting with acute encephalopathy, unprovoked seizures and cerebellar signs. While typical magnetic resonance imaging (MRI) findings strongly support the diagnosis, electroencephalography (EEG) features have been rarely reported and poorly described. We present a longitudinal EEG assessment in one patient with encephalopathy due to metronidazole toxicity who presented a peculiar EEG pattern presentation and evolution. During the acute phase of encephalopathy, the EEG showed a monomorphic, sharply contoured theta activity symmetrically represented over frontal regions with an anterior-posterior progression which evolved in parallel with clinical worsening. Together with a systematic review of the literature, we discuss whether this EEG activity may represent a distinct neurophysiological correlate of 'cerebellar encephalopathy'.

Metronidazole induced encephalopathy: case report and discussion on the differential diagnoses, in particular, Wernicke's encephalopathy

Metronidazole induced encephalopathy is a rare central nervous system toxicity, which may be completely reversible with prompt cessation of metronidazole usage. We present a case of metronidazole induced encephalopathy in a 59-year-old man with a history of Whipple's procedure for pancreatic neuroendocrine tumour. The characteristic magnetic resonance imaging features of metronidazole induced encephalopathy and its main differential diagnosis, Wernicke's encephalopathy, are discussed.

Color tuning of an active pharmaceutical ingredient through cocrystallization: a case study of a metronidazole–pyrogallol cocrystal

The visual color of antimicrobial drug metronidazole is tuned through cocrystallization with pyrogallol, offering a new modification approach.

Metronidazole induced encephalopathy: A rare side effect with a common drug

In hospitals, seizures and encephalopathy are one of the common complications observed in critically ill patients. Drug intoxication, metabolic derangements, and anatomical abnormalities can cause altered mental status. We encountered an uncommon case with a diagnostic dilemma due to persistent encephalopathy, where metronidazole toxicity was an etiological factor. A 45-year-old male, who was admitted with the diagnosis of ruptured amoebic liver abscess. During the course of his management, he developed seizures and altered sensorium. After excluding other etiologies for in-hospital de novo seizure, a suspicion of metronidazole toxicity was considered. MRI brain was done which suggested the same. Metronidazole induced encephalopathy (MIE) is an uncommon adverse effect of treatment with metronidazole. Diagnosis is made by identifying specific radiological findings. It characteristically affects the cerebellum and subcortical structures. While the clinical and neuroimaging changes are usually reversible, persistent encephalopathy with poor outcomes may occur as seen in our case.

Metronidazole-induced Encephalopathy

Metronidazole is commonly used in the treatment of anaerobic infections. While neuropathy is known to be associated with metronidazole, encephalopathy has been rarely reported. We herein present a case of metronidazole-induced encephalopathy presenting as frequent falls and slurred speech. Magnetic resonance imaging of the brain demonstrated T2/FLAIR hyperintensity in the dentate nuclei bilaterally. Soon after the discontinuation of metronidazole, dysarthria and dysmetria resolved. Metronidazole-induced encephalopathy should be considered in patients presenting with new neurologic symptoms after the initiation of metronidazole.

Neurological and Psychiatric Adverse Effects of Antimicrobials

Antimicrobials are a widely used class of medications, but several of them are associated with neurological and psychiatric side effects. The exact incidence of neurotoxicity with anti-infectives is unknown, although it is estimated to be < 1%. Neurotoxicity occurs with all classes of antimicrobials, such as antibiotics, antimycobacterials, antivirals, antifungals and antiretrovirals, with side effects ranging from headaches, anxiety and depression to confusion, delirium, psychosis, mania and seizures, among others. It is important to consider these possible side effects to prevent misdiagnosis or delayed treatment as drug withdrawal can be associated with reversibility in most cases. This article highlights the different neurotoxic effects of a range of antimicrobials, discusses proposed mechanisms of onset and offers general management recommendations. The effects of antibiotics on the gut microbiome and how they may ultimately affect cognition is also briefly examined.

A case of methylprednisolone treatment for metronidazole-induced encephalopathy

Background

Metronidazole, a common antimicrobial agent, can induce encephalopathy in rare cases. After discontinuing metronidazole, most patients show clinical improvement. However, in the face of deteriorating conditions, there have done not to have reports of effective drug treatment.

Case presentation

A 57-year-old man was admitted to our hospital due to dysarthria and ataxic gait after taking metronidazole at the dose of about 32 g for 20 days. Neurological examination showed that his upward and outward movements of bilateral eyeballs were limited, and horizontal and vertical nystagmus were noted. The brain magnetic resonance imaging showed hyper-intensities in the bilateral cerebellar dentate nuclei, medulla oblongata, midbrain and red nuclei in T2W and FLAIR images. However, the patient’s clinical symptoms worsened after drug cessation. High-dose intravenous methylprednisolone pulse therapy was applied, and this led to a drastic improvement of his symptoms and signs.

Conclusions

In our case, we suggest that early methylprednisolone intervention can prevent the progression of metronidazole-induced encephalopathy and accelerate neurological recovery. We infer that the progression of encephalopathy is related to the delayed toxicity caused by high dose or concentration of metronidazole.

Metronidazole: an update on metabolism, structure-cytotoxicity and resistance mechanisms

Metronidazole, a nitroimidazole, remains a front-line choice for treatment of infections related to inflammatory disorders of the gastrointestinal tract including colitis linked to Clostridium difficile. Despite >60 years of research, the metabolism of metronidazole and associated cytotoxicity is not definitively characterized. Nitroimidazoles are prodrugs that are reductively activated (the nitro group is reduced) under low oxygen tension, leading to imidazole fragmentation and cytotoxicity. It remains unclear if nitroimidazole reduction (activation) contributes to the cytotoxicity profile, or whether subsequent fragmentation of the imidazole ring and formed metabolites alone mediate cytotoxicity. A molecular mechanism underpinning high level (>256 mg/L) bacterial resistance to metronidazole also remains elusive. Considering the widespread use of metronidazole and other nitroimidazoles, this review was undertaken to emphasize the structure-cytotoxicity profile of the numerous metabolites of metronidazole in human and murine models and to examine conflicting reports regarding metabolite-DNA interactions. An alternative hypothesis, that DNA synthesis and repair of existing DNA is indirectly inhibited by metronidazole is proposed. Prokaryotic metabolism of metronidazole is detailed to discuss new resistance mechanisms. Additionally, the review contextualizes the history and current use of metronidazole, rates of metronidazole resistance including metronidazole MDR as well as the biosynthesis of azomycin, the natural precursor of metronidazole. Changes in the gastrointestinal microbiome and the host after metronidazole administration are also reviewed. Finally, novel nitroimidazoles and new antibiotic strategies are discussed.

Clinical efficacy of 12-h metronidazole dosing regimens in patients with anaerobic or mixed anaerobic infections

Traditional metronidazole dosing regimens utilize an every 8 h dosing strategy to treat anaerobic and mixed anaerobic infections. However, pharmacokinetic data demonstrate that the half-life of metronidazole is 8-12 h and blood levels at 12 h exceed the in vitro minimum inhibitory concentration (MIC) for most anaerobic infections. The primary objective of this study was to evaluate the frequency of clinical cure among patients who received metronidazole every 12 h compared with those who received an every 8 h frequency. Secondary endpoints included duration of antibiotics, hospital length of stay, escalation of antibiotic therapy, microbiologic cure, and mortality.

METHODS

This retrospective, single-center, pre-post intervention study of 200 patients between June 2014 to July 2016.

RESULTS

No significant differences in clinical cure for every 12 h versus every 8 h metronidazole dosing regimens (85% for both groups, p = 1.00) were found. There were no differences in any of the secondary endpoints, with a mean duration of antibiotic therapy being 5.9 versus 5.8 days and a hospital length of stay averaging 8.1 versus 6.7 days for the 12- and 8-h dosing groups, respectively (p > 0.05).

DISCUSSION

Findings validate pharmacokinetic data suggesting that an extended metronidazole dosing interval effectively treats anaerobic infections.

Convulsive Seizures as Presenting Symptom of Metronidazole-Induced Encephalopathy: A Case Report

Introduction

Encephalopathy and convulsive seizures are rare manifestations of metronidazole toxicity. The incidence is unknown, but the condition has most frequently been reported in patients in their fifth to sixth decades. Usually, this condition is regarded as reversible, but permanent deficits and even death have been reported.

Case Report

A 66-year-old female patient undergoing metronidazole treatment for pleural empyema was admitted to our institution after her second episode of seizure. Over the course of 1 week after admittance, the patient developed several convulsive seizures along with progressive cerebellar dysfunction and cognitive impairment. MRI revealed bilateral, symmetrical hyperintense signal changes in the pons and dentate nuclei. EEG, ECG, lumbar puncture, and blood samples were normal. The patient improved already 2–3 days after discontinuation of metronidazole and was discharged fully recovered after 17 days. Follow-up clinical assessment and MRI were unremarkable.

Conclusion

Metronidazole-induced encephalopathy is a rare condition, and due to a general lack of awareness the diagnosis is often delayed. This condition should be considered in metronidazole-treated patients presenting with unprovoked seizures, myoclonus, cerebellar signs, and encephalopathy. Characteristic MRI lesions may support the clinical suspicion.

Brain and the Liver: Cerebral Edema, Hepatic Encephalopathy and Beyond

Occurrence of brain dysfunction is common in both chronic liver disease as well as acute liver failure. While brain dysfunction most commonly manifests as hepatic encephalopathy is chronic liver disease; devastating complications of cerebral edema and brain herniation syndromes may occur with acute liver failure. Ammonia seems to play a central role in the pathogenesis of brain dysfunction in both chronic liver disease and acute liver failure. In this chapter we outline the pathophysiology and clinical management of brain dysfunction in the critically ill patients with liver disease.

Irreversible metronidazole encephalopathy in an elderly woman with primary biliary cholangitis

An 82‐year‐old woman with primary biliary cholangitis was diagnosed with an irreversible neurological disorder, caused by metronidazole (MNZ)‐induced encephalopathy. Although the disorder is a reversible pathological condition, in rare cases, it can cause serious sequelae or could even be fatal. Therefore, medications should be administered carefully, particularly in patients who require long‐term administration of large doses or those with liver dysfunction.

Clinical and Neuroradiological Spectrum of Metronidazole Induced Encephalopathy: Our Experience and the Review of Literature

Metronidazole is an antimicrobial agent mainly used in the treatment of several protozoal and anaerobic infections, additionally, is often used in hepatic encephalopathy and Crohn disease. Apart from peripheral neuropathy, metronidazole can also cause symptoms of central nervous system dysfunction like ataxic gait, dysarthria, seizures, and encephalopathy which may result from both short term and chronic use of this drug and is collectively termed as "metronidazole induced encephalopathy"(MIE). Neuroimaging forms the backbone in clinching the diagnosis of this uncommon entity, especially in cases where there is high index of suspicion of intoxication. Although typical sites of involvement include cerebellum, brain stem and corpus callosum, however, lesions of other sites have also been reported. Once diagnosed, resolution of findings on Magnetic Resonance Imaging (MRI) of the Brain along with clinical improvement remains the mainstay of monitoring. Here we review the key clinical features and MRI findings of MIE as reported in medical literature. We also analyze implication of use of this drug in special situations like hepatic encephalopathy and brain abscess and discuss our experience regarding this entity.