Metronidazole Exposure Research Articles

Association Between First-time Neurologic Events and Metronidazole Treatment: A Case-time Control Study

PurposeMetronidazole, a widely used antimicrobial medication, has been linked to neurologic adverse drug reactions. This study investigates the association between metronidazole use and first-time neurologic events. MethodsWe conducted a case-time-control study using data from the Danish National Patient Register and the National Prescription Register in years 2013 to 2021. Patients with a first-time diagnosis of encephalopathy, cerebellar dysfunction, or peripheral neuropathy were included. Conditional logistic regression analyses were performed to estimate the risk of neurologic events associated with metronidazole use. FindingsOut of 476,066 first-time metronidazole prescriptions, the 100-day cumulative incidence of peripheral neuropathy was 0.016%, and 0.002% for cerebellar dysfunction or encephalopathy. In the case-time control study, we identified 17,667 persons with a first-time neurologic event and were included for the analysis. The estimated odds ratio for the combined neurologic events was 0.98 (95% CI, 0.59–1.64, P = 0.95) with no statistically significant association across different subgroups and time windows. ImplicationsOur findings suggest that metronidazole-induced neurologic events may be rarer than previously described, and we did not find any consistent or statistically significant association between metronidazole exposure. Nonetheless, clinicians should remain vigilant to potential neurologic risks in patients receiving metronidazole, to ensure its safe and effective use.

Metronidazole Induces the Metazoan Death of Giardia Trophozoites with the Aid of Pyruvate

Background: Metronidazole is the most common drug for the treatment of infectious agent Giardia. The trophozoites need to fight against the oxidative stress generated by metronidazole for their survival. It has been reported that trophozoites possesses several enzymes involved in response to oxidative stress like pyruvate-ferredoxin oxidoreductase, NADH oxidase, peroxiredoxin to combat the harsh condition. These enzyme systems generally act on the amitochondriate trophozoites to attenuate the reactive oxygen species generation which causes cytotoxicity but the actual mechanism of trophozoites death due to metronidazole treatment was still not clear. Methods: The present study aims to establish the effects of pyruvate in Giardia trophozoites exposed to metronidazole treatment. Intracellular reactive oxygen species (ROS) production by Giardia trophozoite suspension was monitored in the presence and absence of pyruvate with the help of a dichlorodihydrofluoresceine diacetate (H2DCFDA) based assay. In the present study, we have investigated the effects of pyruvate on DNA damage in the trophozoites during metronidazole stress. We have also looked into the expression levels of some genes to show their relevance to metronidazole stress. Results: The exogenously addition of physiologically relevant concentration of pyruvate was shown to elevate the rate of ROS generation in Giardia suspension under metronidazole stress. Our results provide evidence that exogenously added pyruvate have induced lipid peroxidation of stressed Giardia. Several known genes are modulated due to the exposure of metronidazole in trophozoites. Conclusion: These results suggest that pyruvate is the key regulatory metabolite that helps generation of different radicals to initiate apoptotic like death in Giardia trophozoites during metronidazole exposure.

Exposure-response Relationships of Metronidazole in Infants: Integration of Electronic Health Record Data With Population Pharmacokinetic Modeling-derived Exposure Simulation.

Infants frequently receive metronidazole at variable doses and duration for surgical site infection prophylaxis and treatment of intra-abdominal infections. Seizures are a rare (but potentially devastating) side effect of metronidazole, yet the prevalence of seizures in infants, as well as the relationship with metronidazole dose and exposure, are unknown. We examined the Pediatrix Clinical Data Warehouse for infants in neonatal intensive care units from 1997 to 2018 who received at least 1 dose of metronidazole during their first 120 days of life. We used an existing population pharmacokinetic model to simulate exposure parameters, estimating multivariable associations between metronidazole dosing and exposure parameters, and the occurrence of seizure. There were 19,367 intravenous doses of metronidazole given to 1546 infants, and 31 experienced a seizure. Infants with a seizure had a longer median (interquartile values) duration of metronidazole exposure than those without (11 days [6, 15] vs. 7 [4, 11], P = 0.01). Each added day of metronidazole (OR = 1.06, 95% CI: 1.02-1.10), and each standard deviation increase in cumulative area under the plasma concentration-time curve (OR = 1.27, 95% CI: 1.11-1.45) were associated with increased odds of seizure. Higher simulated maximum plasma concentration was associated with lower odds of seizure (OR = 0.88, 95% CI: 0.81-0.96). Longer metronidazole exposure and higher cumulative exposure could be associated with increased odds of infant seizures. Using a large observational dataset allowed us to identify a rare adverse event, but prospective studies are needed to validate this finding and further characterize metronidazole dose- and exposure-safety relationships.

The Influence of Past Metronidazole Exposure on the Outcome of Helicobacter pylori Eradication.

BackgroundBismuth quadruple therapy (BQT) is recommended as empirical first-line therapy because it is not affected by antibiotic resistance. We examined whether past exposure to metronidazole affected BQT outcomes.MethodsThe records of seven hospitals were searched for patients who received BQT for Helicobacter pylori eradication between 2009 and 2020. The association between past metronidazole exposure and the eradication rate was evaluated.ResultsThis study was a multicenter retrospective study. Around 37,602 people tested for H. pylori infection were identified, and 7,233 received BQT. About 2,802 (38.7%) underwent a 13C-urea breath test to confirm eradication. The BQT efficacy was 86.4% among patients without metronidazole exposure and 72.8% among patients with exposure (p < 0.001). The eradication rate of BQT 14 days in patients with past exposure was higher than that of BQT <14 days (85.5 vs. 66.0%, p = 0.009). Multivariate analysis revealed that past metronidazole exposure [odds ratio (OR) 2.6, 95% CI 1.8–3.7; p < 0.001] and BQT <14 days (OR 1.5, 95% CI 1.2–2.0; p = 0.002) were independent risk factors for eradication failure.ConclusionPast metronidazole exposure significantly lowered the BQT eradication rate. BQT 14 days should be recommended for patients with suspected metronidazole exposure.

Antibiotics exposure attenuates chronic unpredictable mild stress-induced anxiety-like and depression-like behavior

Antibiotics exposure leads to gut microbiota dysbiosis, which increases the risk of anxiety and depression. However, the impact of ciprofloxacin and metronidazole exposure on chronic unpredictable mild stress-induced anxiety-like and depression-like behavior and underlying regulatory mechanism have not been well established. Here, chronic unpredictable mild stress model was established in adult male Sprague-Dawley rats. 16 S rRNA gene sequencing was used to decipher the gut microbiota. Enzyme-linked immunosorbent assay (ELIZA) was used to measure circulating cytokines in blood, gut barrier permeability biomarkers in feces, blood-brain barrier permeability biomarkers in brain. We found that antibiotics exposure significantly reduced the body weight, weight gain and liver health in chronic unpredictable mild stress treated rats. Behavioral testing suggested that antibiotics exposure reduced anxiety-like and depression-like behavior of rat. Antibiotics exposure possessed lower bacterial richness and diversity than that in the chronic unpredictable mild stress treated group. Compared with CUMS or CUMS-e group, higher abundances of Bacteroides, Lactobacillus, Lachnospiraceae and Akkermansia, lower abundances of S24–7, Blautia, Ruminocaceae, Ruminococcus and Prevotella were found in the gut microbiota from antibiotics exposure group. In addition, short-term antibiotics exposure increased the level of 5-hydroxytryptamine (5-HT) in brain. A significant correlation between certain bacteria and behavior of rats was observed, such as Roseburia. Our study uncovers the role for antibiotics in regulating chronic unpredictable mild stress-induced anxiety-like and depression-like behavior and suggest that short-term antibiotics exposure may be could reverse chronic unpredictable mild stress-induced anxiety-like and depression-like behavior.

A Pilot Evaluation of the Possible Association of Metronidazole With Neurodevelopmental Outcomes in Premature Neonates.

Metronidazole is recommended as a first-line treatment of necrotizing enterocolitis (NEC) in neonates. Metronidazole-associated neurotoxicity has been reported, but long-term neurodevelopmental effects in neonates have not been explored. The primary objective was to evaluate the relationship of cumulative metronidazole dose with each Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) composite score in neonates with NEC. Secondary objectives included comparison of seizure rates, mean Bayley-III scores, and neurodevelopmental impairment defined as 2 of 3 Bayley-III composite scores ≤ 79 or 1 score ≤ 70 between the metronidazole exposed and non-exposed groups. This multisite, retrospective cohort study compared infants with a birth weight < 1500 grams between January 1, 2011, and December 31, 2016, who developed stage 2 or greater NEC or spontaneous intestinal perforation and were followed up at a developmental clinic visit at approximately 1 year of age. Patients were excluded if admitted >72 hours of life, had congenital neurodevelopmental anomalies, hypoxic ischemic encephalopathy, grade III or IV intraventricular hemorrhage, or seizures prior to treatment of NEC. Included patients were stratified into 2 groups based on metronidazole exposure versus no metronidazole. Data were assessed using descriptive and inferential statistical techniques, using SAS 9.4. Forty-one patients were included. Seven patients received metronidazole and 34 patients were in the non-metronidazole group. The only statistical difference noted between groups was for gestational age, with the non-exposed group being more premature. There was no statistical difference in Bayley-III scores, seizure rates, or neurodevelopmental impairment between groups. No differences in neurodevelopmental outcomes were found between those with and without metronidazole exposure. Further studies are needed to validate our results.

Investigating the efficacy and safety of metronidazole during pregnancy; A systematic review and meta-analysis.

ObjectiveWe aimed to review and analyze studies focusing on the efficacy of metronidazole in reducing the risk of preterm birth and the safety of metronidazole taking into account the different doses, duration of treatment and routes of administration.Study designsEmbase, Cochrane Library and PubMed were searched up to 29 July 2019 to identify studies assessing metronidazole exposure during pregnancy. Additional studies were identified from reference lists of retrieved papers. Measured outcomes were preterm births (<37 weeks of gestation) and associated delivery outcomes such as spontaneous abortions (≤ 20 weeks of gestation), stillbirths (≥20 weeks of gestation) and low birth weight (<2500 g) irrespective of the period of exposure and major malformations after first-trimester exposure. Overall effect estimates for RCTs and observational studies were calculated using the random-effects model and pooled using Risk Ratios (RR) and Odds Ratios (OR) respectively. ROB-2 and ROBINS-I tool were used to assess Risk of Bias for RCTs and observational studies, respectively.ResultsTwenty-four studies (17 observational studies and 7 RCTs) were selected. Pooled RR was 1.10 (95 % CI 0.78–1.55; n = 7; I2 = 72 %) for preterm birth. Subgroup analysis found RR 1.67; 95 % CI 1.07–2.62; n = 3; I² = 32 %) for treatment duration of ≤3 days among women with a previous preterm delivery. Pooled OR for spontaneous abortion was 1.72 (95 % CI 1.40–2.12; n = 5; I2 = 72 %) and 1.15 (95 % CI 0.98–1.34; n = 12; I2 = 25 %) for major malformations. After exclusion of studies with critical risk of bias, pooled OR were 1.7 (1.42–2.04; n = 3; I2 = 19 %) and 1.13 (0.93–1.36; n = 9; I2 = 28 %) respectively. Among several specific malformations analyzed, only congenital hydrocephaly was significantly increased at 4.06 (95 % CI 1.75–9.42; n = 2; I² = 0%).ConclusionsData do not confirm the efficacy of metronidazole in reducing the risk of preterm birth and associated delivery outcomes. Further research is required to confirm the effect of high dose and short duration of metronidazole treatment on preterm birth among the high-risk group. Regarding the increased odds of spontaneous abortion, RCTs are required to assess the role of the underlying infection. The need for further studies to confirm the risk of congenital hydrocephaly is paramount.

798. Metronidazole Exposure Prior to Clostridiodes difficile Infection (CDI) is a Risk Factor for Severe C. difficile Disease in Cancer Patients

BackgroundAntibiotic use is a risk factor for CDI. Few studies have correlated use of prior antibiotics with CDI severity in cancer patients. This study identified clinical and microbiology risk factors associated with severe CDI in patients with cancer. We hypothesized that previous antibiotic exposure and microbiome composition at time of CDI presentation, are risk factors for severe disease in cancer patients.MethodsThis non-interventional, prospective, single-center cohort study examined patients with cancer who had their first episode or first recurrence of CDI between Oct 27, 2016 and Jul 1, 2019. C. difficile was identified using nucleic acid amplification testing. Multivariate analysis was used to determine significant clinical risk factors for severe CDI as defined in the 2018 IDSA/SHEA guidelines. Alpha, and beta diversities were calculated to measure the average species diversity and the overall microbial composition. Differential abundance analysis and progressive permutation analysis were used to single out the significant microbial features that differed across CDI severity levels.ResultsPatient (n=200) demographics show mean age of 60 yrs., 53% female, majority White (76%) and non-Hispanic (85%). Prior 90 day metronidazole use (Odds Ratio OR 4.68 [1.47-14.91] p0.009) was a significant risk factor for severe CDI. Other factors included Horn’s Index > 2 (OR 7.75 [1.05-57.35] p0.045), Leukocytosis (OR 1.29 [1.16-1.43] p< 0.001), Neutropenia (OR 6.01 [1.34-26.89] p0.019) and Serum Creatinine >0.95 mg/dL (OR 25.30 [8.08-79.17] p< 0.001). Overall, there were no significant differences in alpha and beta diversity between severity levels. However, when identifying individual microbial features, the high presence of Bacteroides uniformis, Ruminococceae, Citrobacter koseri and Salmonella were associated with protection from severe CDI (p< 0.05).Table 1 - Results of multivariate logistic regression analysis of factors associated with severe CDI Figure 1. Microbiome features identified by progressive permutation analysis as seen in a volcano plot. ConclusionA number of risk factors for severe CDI were identified among this population, including prior 90 day metronidazole use. Also, increased relative abundance of Bacteroides uniformis, Ruminococceae, Citrobacter koseri and Salmonella were linked to protection from severe CDI. Reducing metronidazole use in patients with cancer may help prevent subsequent severe CDI.Disclosures Adilene Olvera, MPH MLS (ASCP), MERK (Grant/Research Support, Scientific Research Study Investigator) Kevin W. Garey, PharmD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator) Ryan J. Dillon, MSc, Merck & Co., Inc., (Employee) Engels N. Obi, PhD, Merck & Co. (Employee)

Impact of previous metronidazole exposure on metronidazole-based second-line quadruple therapy for Helicobacter pylori infection

Background/AimsThe negative effects on the eradication success of Helicobacter pylori infection after previous exposure to macrolides, including clarithromycin on clarithromycin-based first-line therapy have been demonstrated. However, whether this is true for metronidazole-based second-line quadruple therapy remains unclear. We investigated the relationship between past administration of metronidazole and the failure of metronidazole-based second-line quadruple therapy in patients with H. pylori infection.MethodsPatients over 20 years of age who were diagnosed with H. pylori infection between January 1998 and March 2016 were enrolled in this study. The relationship between the clinical parameters and the results of a C13-urea breath test after metronidazole-based second-line quadruple therapy was analyzed in patients for whom clarithromycin-based triple therapy failed to eradicate H. pylori.ResultsThe H. pylori eradication failure rate was significantly higher in patients with a history of metronidazole use than in patients without a history of metronidazole use (p = 0.011). Multivariable analysis showed that the odds ratio of previous metronidazole use for eradication failure was 3.468 (95% confidence interval, 1.391 to 8.649; p = 0.008). In the subgroup analysis of patients with a history of metronidazole use, the duration of metronidazole use and interval between its use and eradication therapy did not significantly affect H. pylori eradication failure.ConclusionsPrevious exposure to metronidazole was a significant risk factor for treatment failure of metronidazole-based second-line quadruple therapy; therefore, this should be considered when establishing a treatment strategy for patients with H. pylori infection.

Metronidazole-associated Neurologic Events: A Nested Case-control Study.

Case reports have described instances of peripheral and central nervous system toxicity during treatment with metronidazole; however, no large-scale studies have examined this association. We conducted a population-based nested case-control study of adults aged 66 years or older living in Ontario, Canada, between 1 April 2003 and 31 March 2017. Cases were individuals who attended hospital for any of cerebellar dysfunction, encephalopathy, or peripheral neuropathy within 100 days of a prescription for either metronidazole or clindamycin. We matched each case patient with up to 10 event-free control subjects who also received metronidazole or clindamycin. We used conditional logistic regression to test the association between metronidazole exposure and neurologic events, with clindamycin as the reference exposure. We identified 1212 cases with recent use of either metronidazole or clindamycin and 12 098 controls. Neurologic adverse events were associated with an increased odds of metronidazole exposure compared to clindamycin (odds ratio [OR], 1.72 [95% confidence interval {CI}, 1.53-1.94]), which persisted after accounting for patient demographics, comorbidities, and other medication exposures (adjusted odds ratio [aOR], 1.43 [95% CI, 1.26-1.63]). We found a consistent association limited to either central (aOR, 1.46 [95% CI, 1.27-1.68]) or peripheral (aOR, 1.34 [95% CI, 1.02-1.76]) nervous system events. Among metronidazole recipients, the overall incidence of neurologic events at 100 days was approximately 0.25%. Metronidazole is associated with an increased risk of adverse peripheral and central nervous system events relative to clindamycin. Clinicians and patients should be aware of these rare but potentially serious adverse events.

Oral metronidazole use and risk of acute pancreatitis: a population-based case-control study.

ObjectiveOral metronidazole used in combined regimens for Helicobacter pylori eradication has been associated with an increased risk of acute pancreatitis; however, it is less clear whether a similar association exists for single-regimen metronidazole. We, therefore, examined the association of single and combined regimens of oral metronidazole with risk of acute pancreatitis.MethodsIn this population-based case-control study, all individuals in Sweden (aged 40–84 years) hospitalized with acute pancreatitis between January 2006 and December 2008 were identified from a national hospital register (n=5,996). Controls, matched for calendar year, age, and sex, were randomly sampled from a national population register (n=60,681). Data on oral metronidazole and covariates were extracted from national health and prescription registers. Odds ratios (ORs) of acute pancreatitis, according to timing of the latest metronidazole prescription before hospitalization, were estimated using logistic regression models. Confounding by indication was examined by contrasting the main results with the association when amoxicillin was used as exposure. The robustness of results was examined by calculating incidence rate ratios using a self-controlled case series approach.ResultsAfter adjustment for potential confounders, there was a substantially increased risk of acute pancreatitis within 30 days of oral metronidazole exposure, both for single (OR: 4.06; 95% confidence interval [CI]: 1.90–8.64) and combined (OR: 11.80; 95% CI: 6.86–20.28) regimens, compared to nonexposure. In contrast, the adjusted OR was 1.79 (95% CI: 1.25–2.54) for current use of amoxicillin compared to nonexposure. These results were supported by the self-controlled cases series analysis (incidence rate ratio: 3.30; 95% CI: 2.69–4.06, for single and combined regimens of oral metronidazole pooled). There was no strong association between oral metronidazole and acute pancreatitis more than 30 days after exposure.ConclusionThere was an increased risk of acute pancreatitis within 30 days of exposure to single and combined regimens of oral metronidazole. While reverse causality and confounding by indication cannot be entirely excluded, they are unlikely to fully explain the association. These results warrant an increased awareness among physicians.

Clinical and Genomic Characterization of Recurrent Enterococcal Bloodstream Infection in Patients With Acute Leukemia.

BackgroundRates and risk factors for recurrent enterococcal bloodstream infection (R-EBSI) and whether the same genetic lineage causes index EBSI and R-EBSI are unknown in patients with acute leukemia (AL) receiving chemotherapy.MethodsNinety-two AL patients with EBSI from 2010 to 2015 were included. Enterococcal bloodstream infection was defined by 31 positive blood cultures for Enterococcus faecium or Enterococcus faecalis and fever, hypotension, or chills. Clearance was defined by 31 negative cultures 324 hours after last positive culture and defervescence. Recurrent enterococcal bloodstream infection was defined by a positive blood culture for Enterococcus 324 hours after clearance. Categorical variables were reported as proportions and compared by the χ2 test. Continuous variables were summarized by median and interquartile range (IQR) and compared by the Wilcoxon-Mann-Whitney Test. P values <.05 were considered significant. Whole-genome sequencing was performed on available paired BSI isolates from 7 patients.ResultsTwenty-four patients (26%) had 31 episodes of R-EBSI. Median time to R-EBSI (IQR) was 26 (13–50) days. Patients with R-EBSI had significantly longer durations of fever and metronidazole exposure during their index EBSI. Thirty-nine percent of E. faecium R-EBSI isolates became daptomycin-nonsusceptible Enterococcus (DNSE) following daptomycin therapy for index EBSI. Whole-genome sequencing analysis confirmed high probability of genetic relatedness of index EBSI and R-EBSI isolates for 4/7 patients.ConclusionsRecurrent enterococcal bloodstream infection and DNSE are common in patients with AL and tend to occur within the first 30 days of index EBSI. Duration of fever and metronidazole exposure may be useful in determining risk for R-EBSI. Whole-genome sequencing analysis demonstrates that the same strain causes both EBSI and R-EBSI in some patients.

2295

OBJECTIVES/SPECIFIC AIMS: Hematopoietic stem and progenitor cells (HSPCs) function to maintain steady state production of new blood cells and to rapidly respond to blood cell loss. Little is known regarding how HSPCs develop the ability to sense and respond to blood cell loss during embryogenesis. Gaining insight into the robust ability of HSPCs to regenerate blood during early development may allow us to develop therapies to rejuvenate this capacity at any stage. METHODS/STUDY POPULATION: We generated a new hematopoietic-specific and inducible cell ablation zebrafish model to uncover the origins of regenerative capacity in HSPCs during development. These transgenic zebrafish express a cyan fluorescent protein (CFP)-nitroreductase (NTR) fusion construct under the control of the draculin (drl) promoter (drl:CFP-NTR), which restricts NTR expression to blood cells. Co-expression analyses of drl:CFP-NTR with known markers of other blood types including HSPCs (runx1+23:mCherry), erythroid cells (gata1:dsRed), and lymphoid cells (rag2:RFP), revealed drl:CFP-NTR was restricted to HSPCs and erythrocytes. To delineate the regeneration potential of embryonic HSPCs, we exposed drl:CFP-NTR transgenic zebrafish embryos to Metronidazole (MTZ), which results in selective ablation of only NTR-expressing blood cells. Embryos were treated from 2 to 3 days postfertilization and recovery of drl+ and gata1+ cells was evaluated over a 7-day recovery period. RESULTS/ANTICIPATED RESULTS: Following MTZ exposure, the nadir of drl+ cell ablation occurs at 2 days post MTZ (dpM) treatment. During the renewal phase of blood regeneration, we first observe recovery of drl+ cells by about 4 dpM, while more mature blood cells like gata1+ erythrocytes show a delayed recovery at about 6 dpM. Our results suggest that HSPCs can respond to injury as early as 2 days of life and that the HSPC-driven regeneration of embryonic blood cells occurs in a hierarchical fashion, similar to regeneration of the adult blood system. DISCUSSION/SIGNIFICANCE OF IMPACT: We have established a quantitative method for in vivo real-time monitoring of embryonic and larval blood regeneration. A significant advantage of our system is that we can use these insights to guide an in-vivo drug screen for factors that accelerate HSPC-driven blood regeneration in a complex biological environment.

Exploratory Investigation of Bacteroides fragilis Transcriptional Response during In vitro Exposure to Subinhibitory Concentration of Metronidazole

Bacteroides fragilis, member from commensal gut microbiota, is an important pathogen associated to endogenous infections and metronidazole remains a valuable antibiotic for the treatment of these infections, although bacterial resistance is widely reported. Considering the need of a better understanding on the global mechanisms by which B. fragilis survive upon metronidazole exposure, we performed a RNA-seq transcriptomic approach with validation of gene expression results by qPCR. Bacteria strains were selected after in vitro subcultures with subinhibitory concentration (SIC) of the drug. From a wild type B. fragilis ATCC 43859 four derivative strains were selected: first and fourth subcultures under metronidazole exposure and first and fourth subcultures after drug removal. According to global gene expression analysis, 2,146 protein coding genes were identified, of which a total of 1,618 (77%) were assigned to a Gene Ontology term (GO), indicating that most known cellular functions were taken. Among these 2,146 protein coding genes, 377 were shared among all strains, suggesting that they are critical for B. fragilis survival. In order to identify distinct expression patterns, we also performed a K-means clustering analysis set to 15 groups. This analysis allowed us to detect the major activated or repressed genes encoding for enzymes which act in several metabolic pathways involved in metronidazole response such as drug activation, defense mechanisms against superoxide ions, high expression level of multidrug efflux pumps, and DNA repair. The strains collected after metronidazole removal were functionally more similar to those cultured under drug pressure, reinforcing that drug-exposure lead to drastic persistent changes in the B. fragilis gene expression patterns. These results may help to elucidate B. fragilis response during metronidazole exposure, mainly at SIC, contributing with information about bacterial survival strategies under stress conditions in their environment.

Transcriptome Analysis of Chemically-Induced Sensory Neuron Ablation in Zebrafish

Peripheral glia are known to have a critical role in the initial response to axon damage and degeneration. However, little is known about the cellular responses of non-myelinating glia to nerve injury. In this study, we analyzed the transcriptomes of wild-type and mutant (lacking peripheral glia) zebrafish larvae that were treated with metronidazole. This treatment allowed us to conditionally and selectively ablate cranial sensory neurons whose axons are ensheathed only by non-myelinating glia. While transcripts representing over 27,000 genes were detected by RNAseq, only a small fraction (~1% of genes) were found to be differentially expressed in response to neuronal degeneration in either line at either 2 hrs or 5 hrs of metronidazole treatment. Analysis revealed that most expression changes (332 out of the total of 458 differentially expressed genes) occurred over a continuous period (from 2 to 5 hrs of metronidazole exposure), with a small number of genes showing changes limited to only the 2 hr (55 genes) or 5 hr (71 genes) time points. For genes with continuous alterations in expression, some of the most meaningful sets of enriched categories in the wild-type line were those involving the inflammatory TNF-alpha and IL6 signaling pathways, oxidoreductase activities and response to stress. Intriguingly, these changes were not observed in the mutant line. Indeed, cluster analysis indicated that the effects of metronidazole treatment on gene expression was heavily influenced by the presence or absence of glia, indicating that the peripheral non-myelinating glia play a significant role in the transcriptional response to sensory neuron degeneration. This is the first transcriptome study of metronidazole-induced neuronal death in zebrafish and the response of non-myelinating glia to sensory neuron degeneration. We believe this study provides important insight into the mechanisms by which non-myelinating glia react to neuronal death and degeneration in sensory circuits.

Risk of Clostridium difficile infection in intensive care unit patients with sepsis exposed to metronidazole

Background: Antimicrobial agents used to treat Clostridium difficile infection (CDI), such as metronidazole and vancomycin, have been used during antibiotic treatment of other infections to try to prevent the development of CDI. We evaluated the hypothesis that intensive care unit (ICU) patients who receive metronidazole as part of an antibiotic treatment regimen for sepsis have a lower risk of subsequently developing CDI. Methods: This was a nested case-control study in a cohort of ICU patients who received antibiotic therapy for sepsis. Results: A total of 10 012 patients aged ≥ 18 years were admitted to the Cooper University Hospital medical/surgical ICU from 1/1/2003 to 12/31/2008. After applying inclusion criteria including having received antibiotic therapy for sepsis and subsequently having developed CDI, 67 cases were identified. The cases were matched for age, gender, date of ICU admission, and hospital length of stay to 67 controls that also received antibiotic therapy for sepsis but did not subsequently develop CDI. In the multivariate analysis, there was no association between metronidazole exposure and the risk of CDI (odds ratio (OR) = 0.57; p = 0.23). The only significant associations on multivariate analysis were antifungal therapy (OR = 0.30; p = 0.02) and aminoglycoside and/or colistin therapy (OR = 0.17; p = 0.02). Conclusions: No association was found between metronidazole use and subsequent CDI in ICU patients who received antibiotic therapy for sepsis.

Evaluation of the effect of oritavancin on Clostridium difficile spore germination, outgrowth and recovery

Previous work suggests oritavancin may be inhibitory to Clostridium difficile spores. We have evaluated the effects of oritavancin exposure on C. difficile spore germination, outgrowth and recovery. Germination and outgrowth of C. difficile spores exposed to different concentrations of oritavancin, vancomycin, or metronidazole (0.1-10 mg/L) were monitored at 0, 2, 4, 6, 24 and 48 h using phase-contrast microscopy. Recovery of antimicrobial-exposed spores was determined by viable counting on Brazier's modified CCEYL agar. Persistence of oritavancin activity on spores after washing was determined by measuring activity against a Staphylococcus aureus lawn. Oritavancin, vancomycin and metronidazole exposure did not prevent germination of phase-bright spores to phase-dark spores, but did inhibit further outgrowth into vegetative cells. The inhibitory effect of oritavancin persisted after washing, whereas the inhibitory effects of vancomycin and metronidazole did not. Oritavancin exposure affected spore recovery; fewer spores were recovered after washing following oritavancin exposure than vancomycin exposure. The extent of this effect was dependent on PCR ribotype, with recovery of ribotype 078 spores completely prevented, but recovery of ribotype 001 spores only slightly affected. Spores exposed to oritavancin, but not vancomycin, retained antimicrobial activity after washing, indicating adherence of oritavancin, but not vancomycin, to the spore surface Oritavancin may adhere to spores, potentially causing early inhibition of germinated cells, preventing subsequent vegetative outgrowth and spore recovery. This may prevent some recurrences of symptomatic C. difficile infection that are due to germination of residual spores following antibiotic therapy.

Crohn's Disease Initially Accompanied by Deep Vein Thrombosis and Ulnar Neuropathy without Metronidazole Exposure

Extraintestinal manifestations are not uncommon in Crohn's disease, and a thromboembolic event is a disastrous potential complication. Deep vein thrombosis is the most common manifestation of a thromboembolic event and typically occurs in association with active inflammatory disease. Peripheral neuropathy in Crohn's disease has rarely been reported and is considered an adverse effect of metronidazole therapy. Here, we describe a patient who was initially diagnosed with Crohn's disease complicated with deep vein thrombosis and ulnar neuropathy without metronidazole exposure. The simultaneous occurrence of these complications in the early stage of Crohn's disease has never been reported in the English literature.

Oxidative damage and antioxidant response of Allium cepa meristematic and elongation cells exposed to metronidazole

The toxicity of metronidazole (MTZ) in meristematic and elongation zones of Allium cepa roots was analyzed for 30 h of exposition. Toxic effects were evaluated by lipid peroxidation (content of thiobarbituric-reactive substances [TBARS]), reduced glutathione (GSH) levels, ascorbate acid and dehydroascorbate acid content, and enzymatic activities of superoxide dismutase and catalase. The root zones showed differentiated susceptibility to MTZ. In the elongation zone, MTZ induced an increase of TBARS content and a significant rise in GSH levels, whereas in the meristematic zone, lipid peroxidation was not observed and all antioxidant defense parameters analyzed were significantly increased. These results indicate that MTZ exposure induced oxidative stress in A. cepa roots, and that the antioxidant defenses in the meristematic zone are more efficient compared with the elongation zone, which is probably related to higher oxidative metabolism of meristematic tissue.

Antibiotic Exposure as a Risk Factor for Fluconazole-Resistant Candida Bloodstream Infection

Recent exposure to azoles is an important risk factor for infection with fluconazole-resistant Candida spp., but little is known about the role of antibacterial drug exposure in the emergence of drug-resistant Candida. We did a prospective nationwide surveillance study of candidemia in Israel and analyzed the propensity score-adjusted association between antifungal and antibacterial drug exposure and bloodstream infection with C. glabrata and fluconazole-resistant Candida isolates. Four hundred forty-four episodes of candidemia (450 Candida isolates, 69 [15%] C. glabrata isolates, and 38 [8.5%] fluconazole-resistant isolates) from 18 medical centers in Israel were included. C. glabrata bloodstream infection was strongly associated with recent metronidazole exposure (odds ratio [OR], 3.2; P < 0.001). Infection with a fluconazole-resistant isolate was associated with exposure to carbapenems, trimethoprim-sulfamethoxazole, clindamycin, and colistin (odds ratio, 2.8; P = 0.01). The inclusion of antibacterial drug exposure in a multivariable model significantly enhanced the model's predictive accuracy for fluconazole-resistant Candida bloodstream infection. Our findings may be relevant to the selection of empirical antifungal treatment and broaden the scope of antibiotic-associated collateral damage.