Characterization of Flagellum and Toxin Phase Variation inClostridioides difficileRibotype 012 Isolates

ABSTRACTClostridioides difficilecauses diarrheal diseases mediated in part by the secreted toxins TcdA and TcdB.C. difficileproduces flagella that also contribute to motility and bacterial adherence to intestinal cells during infection. Flagellum expression and toxin gene expression are linked via the flagellar alternative sigma factor, SigD. Recently, we identified a flagellar switch upstream of the early flagellar biosynthesis operon that mediates phase variation of both flagellum and toxin production inC. difficilestrain R20291. However, we were unable to detect flagellar switch inversion inC. difficilestrain 630, a ribotype 012 strain commonly used in research labs, suggesting that the strain is phase locked. To determine whether a phase-locked flagellar switch is limited to 630 or present more broadly in ribotype 012 strains, we assessed the frequency and phenotypic outcomes of flagellar switch inversion in multipleC. difficileribotype 012 isolates. The laboratory-adapted strain JIR8094, a derivative of strain 630, and six clinical and environmental isolates were all found to be phase-off, nonmotile, and attenuated for toxin production. We isolated low-frequency motile derivatives of JIR8094 with partial recovery of motility and toxin production and found that additional changes in JIR8094 impact these processes. The clinical and environmental isolates varied considerably in the frequency by which flagellar phase-on derivatives arose, and these derivatives showed fully restored motility and toxin production. Taken together, these results demonstrate heterogeneity in flagellar and toxin phase variation amongC. difficileribotype 012 strains and perhaps other ribotypes, which could impact disease progression and diagnosis.IMPORTANCEC. difficileproduces flagella that enhance bacterial motility and secretes toxins that promote diarrheal disease symptoms. Previously, we found that production of flagella and toxins is coregulated via a flippable DNA element termed the flagellar switch, which mediates the phase-variable production of these factors. Here, we evaluate multiple isolates ofC. difficileribotype 012 strains and find them to be primarily flagellar phase off (flg-off state). Some, but not all, of these isolates showed the ability to switch betweenflg-on and -off states. These findings suggest heterogeneity in the ability ofC. difficileribotype 012 strains to phase-vary flagellum and toxin production, which may broadly apply to pathogenicC. difficile.

Download Full-text

Characterization of flagellar and toxin phase variation inClostridium difficileribotype 012 isolates

10.1101/256883 ◽

2018 ◽

Author(s):

Brandon R. Anjuwon-Foster ◽

Natalia Maldonado-Vazquez ◽

Rita Tamayo

Keyword(s):

Clostridium Difficile ◽

Diarrheal Disease ◽

Low Frequency ◽

Phase Variation ◽

Toxin Production ◽

Toxin Gene ◽

Phase Variable ◽

Partial Recovery ◽

Environmental Isolates ◽

Flagellar Biosynthesis

AbstractClostridium difficilecauses diarrheal diseases mediated in part by the secreted toxins TcdA and TcdB.C. difficileproduces flagella that also contribute to motility and bacterial adherence to intestinal cells during infection. Flagellum and toxin gene expression are linked via the flagellar alternative sigma factor, SigD. Recently, we identified a “flagellar switch” upstream of the early flagellar biosynthesis operon that mediates phase variation of both flagellum and toxin production inC. difficilestrain R20291. However, we were unable to detect flagellar switch inversion inC. difficilestrain 630, a ribotype 012 strain commonly used in research labs, suggesting the strain is phase-locked. To determine whether a “phase locked” flagellar switch is limited to 630 or present more broadly in ribotype 012 strains, we assessed the frequency and phenotypic outcomes of flagellar switch inversion in multipleC. difficileribotype 012 isolates. The laboratory-adapted strain JIR8094, a derivative of strain 630, and six clinical and environmental isolates were all found to be phase OFF, non-motile, and attenuated for toxin production. We isolated low frequency motile derivatives of JIR8094 with partial recovery of motility and toxin production, and found that additional changes in JIR8094 impact these processes. The clinical and environmental isolates varied considerably in the frequency by which flagellar phase ON derivatives arose, and these derivatives showed fully restored motility and toxin production. Taken together, these results demonstrate heterogeneity in flagellar and toxin phase variation amongC. difficileribotype 012 strains, and perhaps other ribotypes, which could impact disease progression and diagnosis.ImportanceClostridium difficilecauses diarrheal disease resulting in significant morbidity and mortality in many countries.C. difficileproduces flagella that enhance bacterial motility, and secretes toxins that promote diarrheal disease symptoms. Previously, we found that production of flagella and toxins are co-regulated via a flippable DNA element termed the “flagellar switch”, which mediates the phase variable production of these factors.C. difficilecan exist as flagellated, motile, toxigenic bacteria (“flgON”) or aflagellate, non-motile, nontoxigenic bacteria (“flgOFF”) due in part to the flagellar switch orientation. Here we evaluate multiple isolates ofC. difficileribotype 012 strains and find them to be primarilyflgOFF. Some, but not all, of these isolates showed the ability to switch betweenflgON and OFF states. These findings suggest heterogeneity in the ability ofC. difficileribotype 012 strains to phase vary flagellum and toxin production, which may broadly apply to pathogenicC. difficile.

Download Full-text

Spo0A Suppresses sin Locus Expression in Clostridioides difficile

mSphere ◽

10.1128/msphere.00963-20 ◽

2020 ◽

Vol 5 (6) ◽

Author(s):

Babita Adhikari Dhungel ◽

Revathi Govind

Keyword(s):

Diarrheal Disease ◽

Toxin Production ◽

The United States ◽

Upstream Region ◽

Pcr Analysis ◽

Bacterial Cells ◽

Master Regulator ◽

Content Type ◽

Clostridioides Difficile

ABSTRACT Clostridioides difficile is the leading cause of nosocomial infection and is the causative agent of antibiotic-associated diarrhea. The severity of the disease is directly associated with toxin production, and spores are responsible for the transmission and persistence of the organism. Previously, we characterized sin locus regulators SinR and SinR′ (we renamed it SinI), where SinR is the regulator of toxin production and sporulation. The SinI regulator acts as its antagonist. In Bacillus subtilis, Spo0A, the master regulator of sporulation, controls SinR by regulating the expression of its antagonist, sinI. However, the role of Spo0A in the expression of sinR and sinI in C. difficile had not yet been reported. In this study, we tested spo0A mutants in three different C. difficile strains, R20291, UK1, and JIR8094, to understand the role of Spo0A in sin locus expression. Western blot analysis revealed that spo0A mutants had increased SinR levels. Quantitative reverse transcription-PCR (qRT-PCR) analysis of its expression further supported these data. By carrying out genetic and biochemical assays, we show that Spo0A can bind to the upstream region of this locus to regulates its expression. This study provides vital information that Spo0A regulates the sin locus, which controls critical pathogenic traits such as sporulation, toxin production, and motility in C. difficile. IMPORTANCE Clostridioides difficile is the leading cause of antibiotic-associated diarrheal disease in the United States. During infection, C. difficile spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. In C. difficile, the sin locus is known to regulate both sporulation and toxin production. In this study, we show that Spo0A, the master regulator of sporulation, controls sin locus expression. Results from our study suggest that Spo0A directly regulates the expression of this locus by binding to its upstream DNA region. This observation adds new detail to the gene regulatory network that connects sporulation and toxin production in this pathogen.

Download Full-text

RstA Is a Major Regulator ofClostridioides difficileToxin Production and Motility

mBio ◽

10.1128/mbio.01991-18 ◽

2019 ◽

Vol 10 (2) ◽

Cited By ~ 10

Author(s):

Adrianne N. Edwards ◽

Brandon R. Anjuwon-Foster ◽

Shonna M. McBride

Keyword(s):

Gene Expression ◽

Dna Binding ◽

Toxin Production ◽

Toxin Gene ◽

Dna Binding Domain ◽

Content Type ◽

Toxin Genes ◽

Clostridioides Difficile ◽

Species Specific ◽

Toxin Gene Expression

ABSTRACTClostridioides difficileinfection (CDI) is a toxin-mediated diarrheal disease. Several factors have been identified that influence the production of the two majorC. difficiletoxins, TcdA and TcdB, but prior published evidence suggested that additional unknown factors were involved in toxin regulation. Previously, we identified aC. difficileregulator, RstA, that promotes sporulation and represses motility and toxin production. We observed that the predicted DNA-binding domain of RstA was required for RstA-dependent repression of toxin genes, motility genes, andrstAtranscription. In this study, we further investigated the regulation of toxin and motility gene expression by RstA. DNA pulldown assays confirmed that RstA directly binds therstApromoter via the predicted DNA-binding domain. Through mutational analysis of therstApromoter, we identified several nucleotides that are important for RstA-dependent transcriptional regulation. Further, we observed that RstA directly binds and regulates the promoters of the toxin genestcdAandtcdB, as well as the promoters for thesigDandtcdRgenes, which encode regulators of toxin gene expression. Complementation analyses with theClostridium perfringensRstA ortholog and a multispecies chimeric RstA protein revealed that theC. difficileC-terminal domain is required for RstA DNA-binding activity, suggesting that species-specific signaling controls RstA function. Our data demonstrate that RstA is a transcriptional repressor that autoregulates its own expression and directly inhibits transcription of the two toxin genes and two positive toxin regulators, thereby acting at multiple regulatory points to control toxin production.IMPORTANCEClostridioides difficileis an anaerobic, gastrointestinal pathogen of humans and other mammals.C. difficileproduces two major toxins, TcdA and TcdB, which cause the symptoms of the disease, and forms dormant endospores to survive the aerobic environment outside the host. A recently discovered regulatory factor, RstA, inhibits toxin production and positively influences spore formation. Herein, we determine that RstA directly binds its own promoter DNA to repress its own gene transcription. In addition, our data demonstrate that RstA directly represses toxin gene expression and gene expression of two toxin gene activators, TcdR and SigD, creating a complex regulatory network to tightly control toxin production. This study provides a novel regulatory link betweenC. difficilesporulation and toxin production. Further, our data suggest thatC. difficiletoxin production is regulated through a direct, species-specific sensing mechanism.

Download Full-text

Strain-Dependent RstA Regulation of Clostridioides difficile Toxin Production and Sporulation

Journal of Bacteriology ◽

10.1128/jb.00586-19 ◽

2019 ◽

Vol 202 (2) ◽

Cited By ~ 1

Author(s):

Adrianne N. Edwards ◽

Ellen G. Krall ◽

Shonna M. McBride

Keyword(s):

Gene Expression ◽

Gastrointestinal Tract ◽

Toxin Production ◽

Spore Formation ◽

Toxin Gene ◽

Disease Symptoms ◽

Content Type ◽

Clostridioides Difficile ◽

Toxin Gene Expression ◽

Strain Dependent

ABSTRACT The anaerobic spore former Clostridioides difficile causes significant diarrheal disease in humans and other mammals. Infection begins with the ingestion of dormant spores, which subsequently germinate within the host gastrointestinal tract. There, the vegetative cells proliferate and secrete two exotoxins, TcdA and TcdB, which cause disease symptoms. Although spore formation and toxin production are critical for C. difficile pathogenesis, the regulatory links between these two physiological processes are not well understood and are strain dependent. Previously, we identified a conserved C. difficile regulator, RstA, that promotes sporulation initiation through an unknown mechanism and directly and indirectly represses toxin and motility gene transcription in the historical isolate 630Δerm. To test whether perceived strain-dependent differences in toxin production and sporulation are mediated by RstA, we created an rstA mutant in the epidemic ribotype 027 strain R20291. RstA affected sporulation and toxin gene expression similarly but more robustly in R20291 than in 630Δerm. In contrast, no effect on motility gene expression was observed in R20291. Reporter assays measuring transcriptional regulation of tcdR, the sigma factor gene essential for toxin gene expression, identified sequence-dependent effects influencing repression by RstA and CodY, a global nutritional sensor, in four diverse C. difficile strains. Finally, sequence- and strain-dependent differences were evident in RstA negative autoregulation of rstA transcription. Altogether, our data suggest that strain-dependent differences in RstA regulation contribute to the sporulation and toxin phenotypes observed in R20291. Our data establish RstA as an important regulator of C. difficile virulence traits. IMPORTANCE Two critical traits of Clostridioides difficile pathogenesis are toxin production, which causes disease symptoms, and spore formation, which permits survival outside the gastrointestinal tract. The multifunctional regulator RstA promotes sporulation and prevents toxin production in the historical strain 630Δerm. Here, we show that RstA exhibits stronger effects on these phenotypes in an epidemic isolate, R20291, and additional strain-specific effects on toxin and rstA expression are evident. Our data demonstrate that sequence-specific differences within the promoter for the toxin regulator TcdR contribute to the regulation of toxin production by RstA and CodY. These sequence differences account for some of the variability in toxin production among isolates and may allow strains to differentially control toxin production in response to a variety of signals.

Download Full-text

RstA Regulation ofClostridioides difficileToxin Production and Sporulation in Phenotypically Diverse Strains

10.1101/774125 ◽

2019 ◽

Author(s):

Adrianne N. Edwards ◽

Ellen G. Krall ◽

Shonna M. McBride

Keyword(s):

Gene Expression ◽

Gastrointestinal Tract ◽

Diarrheal Disease ◽

Toxin Production ◽

Toxin Gene ◽

Disease Symptoms ◽

Clostridioides Difficile ◽

Sequence Dependent ◽

Toxin Gene Expression ◽

Strain Dependent

ABSTRACTThe anaerobic spore-former,Clostridioides difficile, causes significant diarrheal disease in humans and other mammals. Infection begins with the ingestion of dormant spores which subsequently germinate within the host gastrointestinal tract. Here, the vegetative cells proliferate and secrete two exotoxins, TcdA and TcdB, which cause disease symptoms. Although spore formation and toxin production are critical forC. difficilepathogenesis, the regulatory links between these two physiological processes are not well understood and are strain-dependent. Previously, we identified a conservedC. difficileregulator, RstA, that promotes sporulation initiation through an unknown mechanism and directly and indirectly represses toxin gene transcription in the historical isolate, 630Δerm. To test whether perceived strain-dependent differences in toxin production and sporulation are mediated by RstA, we created anrstAmutant in the epidemic 027 ribotype strain, R20291. RstA affects sporulation and toxin gene expression similarly in R20291, although more robust regulatory effects are observed in this strain than in 630Δerm. Reporter assays measuring transcriptional regulation oftcdR, the sigma factor essential for toxin gene expression, identified sequence-dependent effects influencing repression by RstA and CodY, a global nutritional sensor, in four diverseC. difficilestrains. We provide evidence that RstA contributes totcdRbistability in R20291 by biasing cells to a toxin-OFF state. Finally, sequence-dependent and strain-dependent differences were evident in RstA negative autoregulation ofrstAtranscription. Our data establish RstA as an important regulator ofC. difficilevirulence traits, and implicate RstA as a contributor to the variety of sporulation and toxin phenotypes observed in distinct isolates.IMPORTANCETwo critical traits ofClostridioides difficilepathogenesis are the production of toxins, which cause disease symptoms, and the formation of spores, which permit survival outside of the gastrointestinal tract. The multifunctional regulator, RstA, promotes sporulation and prevents toxin production in the historical strain, 630Δerm. Here, we show that RstA functions similarly in an epidemic isolate, R20291, although strain-specific effects on toxin andrstAexpression are evident. Our data demonstrate that sequence-specific differences within the promoter for the toxin regulator, TcdR, contribute to regulation of toxin production by RstA and CodY. These sequence differences account for some of the variability in toxin production among isolates, and may allow strains to differentially control toxin production in response to a variety of signals.

Download Full-text

Temporal Variations in Patterns of Clostridioides difficile Strain Diversity and Antibiotic Resistance in Thailand

Antibiotics ◽

10.3390/antibiotics10060714 ◽

2021 ◽

Vol 10 (6) ◽

pp. 714

Author(s):

Supapit Wongkuna ◽

Tavan Janvilisri ◽

Matthew Phanchana ◽

Phurt Harnvoravongchai ◽

Amornrat Aroonnual ◽

...

Keyword(s):

Antibiotic Resistance ◽

Antimicrobial Susceptibility ◽

Reference Strain ◽

Toxin Production ◽

Temporal Variations ◽

Toxin Gene ◽

Data Sets ◽

Clostridioides Difficile ◽

Life Threatening ◽

Susceptibility Profiles

Clostridioides difficile has been recognized as a life-threatening pathogen that causes enteric diseases, including antibiotic-associated diarrhea and pseudomembranous colitis. The severity of C. difficile infection (CDI) correlates with toxin production and antibiotic resistance of C. difficile. In Thailand, the data addressing ribotypes, toxigenic, and antimicrobial susceptibility profiles of this pathogen are scarce and some of these data sets are limited. In this study, two groups of C. difficile isolates in Thailand, including 50 isolates collected from 2006 to 2009 (THA group) and 26 isolates collected from 2010 to 2012 (THB group), were compared for toxin genes and ribotyping profiles. The production of toxins A and B were determined on the basis of toxin gene profiles. In addition, minimum inhibitory concentration of eight antibiotics were examined for all 76 C. difficile isolates. The isolates of the THA group were categorized into 27 A−B+CDT− (54%) and 23 A-B-CDT- (46%), while the THB isolates were classified into five toxigenic profiles, including six A+B+CDT+ (23%), two A+B+CDT− (8%), five A−B+CDT+ (19%), seven A−B+CDT− (27%), and six A−B−CDT− (23%). By visually comparing them to the references, only five ribotypes were identified among THA isolates, while 15 ribotypes were identified within THB isolates. Ribotype 017 was the most common in both groups. Interestingly, 18 unknown ribotyping patterns were identified. Among eight tcdA-positive isolates, three isolates showed significantly greater levels of toxin A than the reference strain. The levels of toxin B in 3 of 47 tcdB-positive isolates were significantly higher than that of the reference strain. Based on the antimicrobial susceptibility test, metronidazole showed potent efficiency against most isolates in both groups. However, high MIC values of cefoxitin (MICs 256 μg/mL) and chloramphenicol (MICs ≥ 64 μg/mL) were observed with most of the isolates. The other five antibiotics exhibited diverse MIC values among two groups of isolates. This work provides evidence of temporal changes in both C. difficile strains and patterns of antimicrobial resistance in Thailand.

Download Full-text

FliW and CsrA Govern Flagellin (FliC) Synthesis and Play Pleiotropic Roles in Virulence and Physiology of Clostridioides difficile R20291

Frontiers in Microbiology ◽

10.3389/fmicb.2021.735616 ◽

2021 ◽

Vol 12 ◽

Author(s):

Duolong Zhu ◽

Shaohui Wang ◽

Xingmin Sun

Keyword(s):

Bacterial Colonization ◽

Toxin Production ◽

Toxin Gene ◽

Clostridioides Difficile ◽

Significant Difference ◽

Assembly Factor ◽

Carbon Storage Regulator ◽

Transcription Suppression ◽

Post Transcriptional Regulation

Clostridioides difficile flagellin FliC is associated with toxin gene expression, bacterial colonization, and virulence, and is also involved in pleiotropic gene regulation during in vivo infection. However, how fliC expression is regulated in C. difficile remains unclear. In Bacillus subtilis, flagellin homeostasis and motility are coregulated by flagellar assembly factor (FliW), flagellin Hag (FliC homolog), and Carbon storage regulator A (CsrA), which is referred to as partner-switching mechanism “FliW-CsrA-Hag.” In this study, we characterized FliW and CsrA functions by deleting or overexpressing fliW, csrA, and fliW-csrA in C. difficile R20291. We showed that fliW deletion, csrA overexpression in R20291, and csrA complementation in R20291ΔWA (fliW-csrA codeletion mutant) dramatically decreased FliC production, but not fliC gene transcription. Suppression of fliC translation by csrA overexpression can be relieved mostly when fliW was coexpressed, and no significant difference in FliC production was detected when only fliW was complemented in R20291ΔWA. Further, loss of fliW led to increased biofilm formation, cell adhesion, toxin production, and pathogenicity in a mouse model of C. difficile infection (CDI), while fliW-csrA codeletion decreased toxin production and mortality in vivo. Our data suggest that CsrA negatively modulates fliC expression and FliW indirectly affects fliC expression through inhibition of CsrA post-transcriptional regulation. In light of “FliW-CsrA-Hag” switch coregulation mechanism reported in B. subtilis, our data also suggest that “FliW-CsrA-fliC/FliC” can regulate many facets of C. difficile R20291 pathogenicity. These findings further aid us in understanding the virulence regulation in C. difficile.

Download Full-text

Analysis of Invasive NontypeableHaemophilus influenzaeIsolates Reveals Selection for the Expression State of Particular Phase-Variable Lipooligosaccharide Biosynthetic Genes

Infection and Immunity ◽

10.1128/iai.00093-19 ◽

2019 ◽

Vol 87 (5) ◽

Cited By ~ 6

Author(s):

Zachary N. Phillips ◽

Charles Brizuela ◽

Amy V. Jennison ◽

Megan Staples ◽

Keith Grimwood ◽

...

Keyword(s):

Gene Expression ◽

Phase Variation ◽

Phase Variable ◽

Chronic Infections ◽

Biosynthetic Genes ◽

Content Type ◽

Invasive Infections ◽

Acetyl Group ◽

Overt Disease ◽

Expression Status

ABSTRACTNontypeableHaemophilus influenzae(NTHi) is a major human pathogen, responsible for several acute and chronic infections of the respiratory tract. The incidence of invasive infections caused by NTHi is increasing worldwide. NTHi is able to colonize the nasopharynx asymptomatically, and the exact change(s) responsible for transition from benign carriage to overt disease is not understood. We have previously reported that phase variation (the rapid and reversible ON-OFF switching of gene expression) of particular lipooligosaccharide (LOS) glycosyltransferases occurs during transition from colonizing the nasopharynx to invading the middle ear. Variation in the structure of the LOS is dependent on the ON/OFF expression status of each of the glycosyltransferases responsible for LOS biosynthesis. In this study, we surveyed a collection of invasive NTHi isolates for ON/OFF expression status of seven phase-variable LOS glycosyltransferases. We report that the expression state of the LOS biosynthetic genesoafAON andlic2AOFF shows a correlation with invasive NTHi isolates. We hypothesize that these gene expression changes contribute to the invasive potential of NTHi. OafA expression, which is responsible for the addition of anO-acetyl group onto the LOS, has been shown to impart a phenotype of increased serum resistance and may serve as a marker for invasive NTHi.

Download Full-text

ZupT Facilitates Clostridioides difficile Resistance to Host-Mediated Nutritional Immunity

mSphere ◽

10.1128/msphere.00061-20 ◽

2020 ◽

Vol 5 (2) ◽

Cited By ~ 3

Author(s):

Joseph P. Zackular ◽

Reece J. Knippel ◽

Christopher A. Lopez ◽

William N. Beavers ◽

C. Noel Maxwell ◽

...

Keyword(s):

Immune Response ◽

Therapeutic Potential ◽

Neutrophil Infiltration ◽

Toxin Production ◽

Host Protein ◽

Content Type ◽

Nutritional Immunity ◽

Clostridioides Difficile ◽

Therapeutic Development ◽

Dependent Growth

ABSTRACT Clostridioides difficile is a spore-forming bacterium that causes severe colitis and is a major public health threat. During infection, C. difficile toxin production results in damage to the epithelium and a hyperinflammatory response. The immune response to CDI leads to robust neutrophil infiltration at the sight of infection and the deployment of numerous antimicrobials. One of the most abundant host immune factors associated with CDI is calprotectin, a metal-chelating protein with potent antimicrobial activity. Calprotectin is essential to the innate immune response to C. difficile and increasing levels of calprotectin correlate with disease severity in both adults and children with CDI. The fact that C. difficile persists in the presence of high levels of calprotectin suggests that this organism may deploy strategies to compete with this potent antimicrobial factor for essential nutrient metals during infection. In this report, we demonstrate that a putative zinc (Zn) transporter, ZupT, is employed by C. difficile to survive calprotectin-mediated metal limitation. ZupT is highly expressed in the presence of calprotectin and is required to protect C. difficile against calprotectin-dependent growth inhibition. When competing against wild-type C. difficile, zupT mutants show a defect in colonization and persistence in a murine model of infection. Together these data demonstrate that C. difficile utilizes a metal import system to combat nutritional immunity during CDI and suggest that strategies targeting nutrient acquisition in C. difficile may have therapeutic potential. IMPORTANCE During infection, pathogenic organisms must acquire essential transition metals from the host environment. Through the process of nutritional immunity, the host employs numerous strategies to restrict these key nutrients from invading pathogens. In this study, we describe a mechanism by which the important human pathogen Clostridioides difficile resists transition-metal limitation by the host. We report that C. difficile utilizes a zinc transporter, ZupT, to compete with the host protein calprotectin for nutrient zinc. Inactivation of this transporter in C. difficile renders this important pathogen sensitive to host-mediated metal restriction and confers a fitness disadvantage during infection. Our study demonstrates that targeting nutrient metal transport proteins in C. difficile is a potential avenue for therapeutic development.

Download Full-text

2435. The Impact of Treatment Strategy and Toxin Status on Outcomes of Patients with Clostridioides difficile Infections

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.2113 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S842-S842

Author(s):

Daniel Friedman ◽

Karen Zurek ◽

Leyla Asadi ◽

Mao-Cheng Lee ◽

Holly Hoang

Keyword(s):

Treatment Guidelines ◽

Retrospective Chart Review ◽

Toxin Production ◽

Toxin Gene ◽

Composite Outcome ◽

Related Complication ◽

Clostridioides Difficile ◽

Increased Risk ◽

Treatment Escalation ◽

The Impact

Abstract Background Clostridioides difficile infection (CDI) is an important cause of morbidity and mortality and management continues to evolve. For laboratories that diagnose by detection of toxin gene, it is unclear whether reporting toxin production is additive to patient care. Furthermore, is there still a role for metronidazole (MNZ) given treatment guidelines now recommend vancomycin (VAN) as first-line therapy for non-severe cases? We analyzed cases of CDI in our hospital to assess outcomes of patients on MNZ vs. VAN and with or without toxin production. Methods A retrospective chart review of inpatients with CDI (based on detection of C. difficile toxin gene by PCR) was conducted between November 2017 and August 2018. Comparison of demographics and outcomes was performed in a) cases that were toxin-positive by enzyme immunoassay vs. negative and b) non-severe cases initially managed with MNZ vs. VAN. Results 76 patients were included (46 toxin-positive, 30 toxin-negative). Toxin-positive patients were older (mean age 77 vs. 62, p = 0.002) but had similar disease severity and initial treatment. A CDI recurrence occurred in 22% vs 0% in the toxin-positive cases (p = 0.006). Any CDI-related complication occurred in 23% of toxin-negative and 35% of toxin-positive cases (ns). After adjusting for toxin-status, age, and severity, the odds ratio of the composite outcome of any complication with toxin-positive CDI was not significant (OR 1.45 95% CI 0.45 -4.6, p = 0.52). There were 37 (49%) patients with non-severe CDI (27 MNZ, 10 VAN). Patients treated with VAN had higher stooling/day (6.3 vs 4.4, p = 0.04) and heart rate (p = 0.02). Initial MNZ use was associated with treatment escalation in 48% of cases compared with 10% in those treated with VAN alone (p = 0.03). CDI-associated mortality was higher in the VAN group (2/10 vs 0/27, p = 0.017). The rate of other complications was not significantly different. Conclusion Although no difference in the composite outcome of any CDI-related complication was detected between toxin positive vs negative patients, toxin-positivity may predict patients at risk for subsequent recurrence. Patients with non-severe CDI did not have increased risk of complications when managed with MNZ; however, they were more likely to require treatment escalation. Disclosures All authors: No reported disclosures.

Download Full-text