A repeat offender: Recurrent extraintestinal Clostridium difficile infection following fecal microbiota transplantation

Accepted Manuscript A repeat offender: recurrent extraintestinal Clostridium difficile infection following fecal microbiota transplantation

Bradley J. Gardiner, Cheleste M. Thorpe, Nicholas V. Pinkham, Laura A. McDermott, Seth T. Walk, David R. Snydman PII:

S1075-9964(18)30064-7

DOI:

10.1016/j.anaerobe.2018.04.007

Reference:

YANAE 1870

To appear in:

Anaerobe

Received Date:

27 November 2017

Revised Date:

06 April 2018

Accepted Date:

08 April 2018

Please cite this article as: Bradley J. Gardiner, Cheleste M. Thorpe, Nicholas V. Pinkham, Laura A. McDermott, Seth T. Walk, David R. Snydman, A repeat offender: recurrent extraintestinal Clostridium difficile infection following fecal microbiota transplantation, Anaerobe (2018), doi: 10.1016/j.anaerobe.2018.04.007

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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A repeat offender: recurrent extraintestinal Clostridium difficile infection following fecal microbiota transplantation Bradley J. Gardiner1, Cheleste M. Thorpe1,2, Nicholas V. Pinkham3, Laura A. McDermott1, Seth T. Walk3, David R. Snydman1,2 Affiliations: 1Division

of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Boston, MA, USA 2Tufts University School of Medicine, Boston, MA, USA 3Department of Microbiology and Immunology, Montana State University, Bozeman, MT, USA Address for correspondence: Dr Bradley J. Gardiner Division of Geographic Medicine and Infectious Disease Tufts Medical Center 800 Washington St Boston, MA, 02116 [email protected] Running Title: Recurrent extraintestinal C. diff infection Keywords: extraintestinal Clostridium difficile, fecal microbiota transplantation, whole genome sequencing Conflicts of interest: DRS and CMT have received research grant support from Merck, Summit and Actelion. CMT was a member of an advisory board for Summit. All other authors report no conflicts of interest. Financial support: This work was supported by the Tufts Medical Center Division of Geographic Medicine and Infectious Disease Francis P. Tally MD Fellowship. Word count: Abstract 68, Manuscript body 1783 Abbreviations: FMT, fecal microbiota transplantation. CT, computed tomography. MIC, minimum inhibitory concentration. CLSI, Clinical and Laboratory Standards Institute.

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ACCEPTED MANUSCRIPT 43

Abstract

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Extraintestinal infection with Clostridium difficile has been reported but remains

45

uncommon. Treatment of this unusual complication is complex given the limitations

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of current therapeutic options. Here we report a novel case of recurrent

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extraintestinal C. difficile infection that occurred following fecal microbiota

48

transplantation. Using whole genome sequencing, we confirmed recrudescence

49

rather than reinfection was responsible. The patient ultimately responded to

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prolonged, targeted antimicrobial therapy informed by susceptibility testing.

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Introduction

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While Clostridium difficile colitis is an increasingly common and important clinical

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problem, extraintestinal infection remains unusual. Given the limitations of current

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diagnostic and therapeutic modalities, treatment is challenging. We describe a case

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of recurrent extraintestinal C. difficile infection (CDI) that illustrates some of these

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complex management issues.

58 59

Case

60 61

A 51 year-old man with long-standing, well-controlled HIV infection and end-stage

62

renal disease due to HIV nephropathy developed peritoneal-dialysis associated

63

peritonitis with Candida parapsilosis. This was treated with removal of Tenckhoff

64

catheter, transition to hemodialysis and a prolonged course of antifungal therapy as

65

well as laparotomy for abdominal lavage and lysis of adhesions. Post-operatively, he

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developed severe*, refractory CDI that did not respond to oral vancomycin,

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intravenous metronidazole or oral fidaxomicin, but improved following

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colonoscopically-administered fecal microbiota transplantation (FMT), using donor

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stool sourced from OpenBiome, a commercial stool bank based in Somerville, MA.

70 71

Several weeks following this procedure he was readmitted with abdominal pain,

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bloating, poor appetite, weight loss, vomiting, constipation and fevers. He was Characterized by ongoing profuse diarrhea, poor oral intake, abdominal pain and distension. Laboratory markers around the time of diagnosis included total white blood count 25.7 x 103/μL (411), creatinine 9.55 mg/dL (0.57-1.3), lactate 1.9 mEq (0.5-2.2). Albumin, measured several weeks later, was 2.7 g/dL (3.4-4.8). *

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febrile and had a mildly distended abdomen with right lower quadrant tenderness.

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White blood count (WBC) was 24.7 x 103/μL (reference range, RR 4-11 x 103 cells/μL)

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with 71% neutrophils; C-reactive protein was 246 mg/L (RR, 0-7.48 mg/L). A CT scan

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demonstrated multiple loculated fluid collections within the peritoneal cavity (Figure

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1a), the largest two of which were drained percutaneously.

78 79

Analysis of the fluid from the right-sided collection revealed an inflammatory

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exudate containing Gram-positive rods (Figure 1b). After 2 days of anaerobic

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incubation on Brucella Blood agar, fine growth of flat irregular colonies with a

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ground glass appearance was noted, and large Gram variable rods with spores were

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seen microscopically. This organism was identified as Clostridium difficile by Rapid-

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ANA II (Remel Products, Lenexa, KS). Some Candida-like forms were also seen on

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cytologic examination, but yeast did not grow. The patient was treated with

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metronidazole and micafungin. Two weeks later, while still on therapy, he developed

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worsening left sided chest pain with respiratory distress and repeat imaging

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demonstrated a new left sided pleural effusion and an increase in the size of the left

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upper quadrant effusion. Both were drained and grew Serratia marcescens.

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Ertapenem was added to metronidazole and micafungin and drains remained in

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place for several weeks with resolution of his collections and clinical improvement.

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He was treated with all 3 antimicrobials for a total of 3 months.

93 94

One week following discontinuation of antimicrobial therapy, he developed

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abdominal pain, distention, fevers and a WBC of 16.5 x 103/μL (76% neutrophils). A

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repeat CT scan revealed a new right-sided pleural effusion (Figure 1c) and re-

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accumulation of the abdominal collections. The pleural effusion and right lower

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collection were drained percutaneously, and C. difficile was isolated from the pleural

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cavity. Antimicrobial susceptibility testing was performed on both isolates by agar

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dilution as previously described (Table 1) [1]. A timeline of events is shown in Figure

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2.

102 103

Toxin gene profiling was conducted on both isolates by multiplex PCR [2] and PCR

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ribotyping was performed as previously described [3]. Both isolates carried C. difficile

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toxin A and B encoding genes (tcdA and tcdB), were binary toxin gene (cdtA and

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cdtB) negative, and belonged to the same unique ribotype (not currently found in a

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database of >5,000 clinical and environmental isolates collected primarily in the US

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across >15 health care centers), now designated as ‘FP505’ in the Walk Lab database

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(Chromatograms (.fsa) available at thewalklab/tools). Whole genome sequencing

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was performed on both isolates using Illumina MiSeq (150 bp paired-end reads;

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available as a BioProject at NCBI, PRJNA434292), and reads were assembled with

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SPAdes [4] using a read length cut off of 100 base pairs. In silico multilocus sequence

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typing (MLST) revealed that both isolates were identical and belonged to ST139, a

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rare lineage observed in a large hospital in China [5, 6]. Both isolates clustered within

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the previously described diversity of C. difficile (Figure 3) based on phylogenetic

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analysis of 582 non-recombinant, core genome genes. The reference strains used for

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this comparison represent commonly observed ribotypes (017, 012, 027, 001 and

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078) around the world [7]. As with MLST loci, isolates were identical across all 582

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core genes. Raw sequencing reads from both isolates were then mapped onto the

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genome (chromosome) of strain 630 using Bowtie 2 (version 2.3.4.1; default

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settings). Coverage was similar to that observed in other studies (58X and 90X), and

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the majority of reads obtained were successfully mapped (90.02% and 89.65%

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overall alignment rate). In total, 3,569,595 sites were mapped and used to evaluate

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the presence of single nucleotide variants (SNVs) with the mpileup function of

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SAMtools (Version: 1.7) and the following options as described [8, 9]: -E (recalculate

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extended BAQ), -C 0 (disable adjust mapping quality), -Q 25 (skip bases with BAQ less

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than 25), -q 30 (skip alignments with mapQ less than 30), -m 2 (minimum gapped

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reads for indel candidates of 2), -t DP (output per- sample DP in BCF), and -t SP

129

(output per-sample strand bias P-value in BCF). No SNVs were found between the

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two isolates using this pipeline. Thus, all genetic/genomic comparisons conducted

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support recrudescence.

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The patient was initially retreated with metronidazole, however after 6 weeks of

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therapy peripheral neuropathy developed, concerning for drug toxicity. Guided by

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susceptibility testing results, his antimicrobial regimen was changed to oral

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amoxicillin-clavulanate, which was stopped after an additional 8 months following

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clinical and radiologic improvement. He remains well without evidence of further

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relapse more than 1 year following treatment completion.

139 140

Discussion

141 142

Clostridium difficile is an anaerobic, gram-positive, spore-forming, toxin-producing

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bacillus that is a common cause of antibiotic-associated diarrhea, particularly in the

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hospital setting [10, 11]. Incidence has been increasing over the last 20 years, and

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there can be high attributable morbidity and mortality especially in patients with

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comorbid medical conditions. The organism produces toxins, which exert cytopathic

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effect on colonic mucosa but have minimal pathogenicity outside of the

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gastrointestinal tract. Current therapies include oral/intravenous metronidazole and

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oral vancomycin, which is now typically used first line. Following the successful

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treatment of acute infection, recurrence can occur in up to 30% and can be difficult

151

to treat [10-12]. Fidaxomicin is a new, poorly absorbed antibiotic that appears to

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have equivalent cure rate to vancomycin but lower risk of recurrence [12].

153 154

Cases of extraintestinal CDI are uncommon but have been reported in the literature

155

over the past 20 years [13-16]. These small retrospective cohort studies have

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described over 100 predominantly hospitalized patients with significant co-

157

morbidities who received prolonged courses of antimicrobial therapy. Most cases of

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extraintestinal infection have been associated with intestinal perforation or other

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disruption to the colonic wall and secondary fecal contamination of the peritoneal

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cavity. In this setting, infection is generally polymicrobial and reported outcomes

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typically poor with mortality rates of 30-40%, dependent on the underlying disease

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state. Many patients required surgical intervention or percutaneous drainage of

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abscesses, and metronidazole-containing regimens have typically been used.

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Monomicrobial infection has occurred in an array of anatomic locations including the

165

pleural cavity [17], wounds [18, 19], bloodstream [20], central nervous system [21]

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and bone/joint [22, 23]. In our patient, the source of the extraintestinal infection

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was unclear, with possibilities including seeding of fluid collections from undetected

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bacteremia around the time of initial CDI, or translocation of the organism through

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the colonic mucosa at the time of FMT, although the appearance of the colon at

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colonoscopy was normal and this complication has not previously been reported.

171 172

While whole genome sequencing has been previously used to distinguish intestinal

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reinfection from relapse [24], ours is the first reported case of proven extraintestinal

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recrudescence confirmed by modern molecular methods. In addition, using this

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strategy we were able to identify a sequence type of C. difficile not previously seen

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in the US and a rare, if not novel, ribotype in our database. Whole genome

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sequencing, once restricted for research use only, is an increasingly accessible tool

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for real-time investigation of public health outbreaks and other clinical applications

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such as accurate organism identification, typing, resistance detection and virulence

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profiling [25]. This technique is increasingly being applied to many infections

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including CDI [26, 27]. In our patient, the initial diagnosis was made by GDH positive,

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toxin negative screening with C. diff Quik Check Complete® (TechLab®, Blacksburg,

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VA/Alere™, Orlando, FL, USA) then secondary confirmation by Illumigene® PCR

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testing (Meridian Bioscience Inc., Cincinatti, OH, USA). Unfortunately the positive

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stool had been discarded prior to the diagnosis of the extraintestinal episode, and

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therefore the initial isolate of C. difficile was not available for additional testing. It is

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unclear why our patient had recrudescence of extraintestinal CDI after aggressive

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treatment, as the second isolate was not more resistant that the first. Factors that

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may have led to this could include persistence of viable spores unaffected by

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antibiotic exposure, incomplete drainage of collections, inadequate duration of

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initial therapy, or poor penetration/activity of metronidazole in body fluid.

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Treatment of extra-intestinal CDI is complex. Vancomycin and fidaxomicin are not

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systemically absorbed so oral administration of these agents does not result in

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therapeutic levels outside the gastrointestinal tract. Metronidazole does have high

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oral bioavailability, but prolonged use can be complicated by toxicity, as it was in our

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patient. Performing antimicrobial susceptibility testing in anaerobes remains largely

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restricted to specialized reference laboratories, so antimicrobial therapy for patients

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with serious infections due to anaerobic bacteria is often empiric. However, given

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that resistance among anaerobic organisms is increasing, in certain situations it is

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critical to have susceptibility data available in real time to guide individual patient

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management, and collected for epidemiologic surveillance to understand general

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patterns of resistance. We were fortunate to have access to a specialized reference

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laboratory capable of performing testing of our isolate for a broad range of

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antimicrobials, and we used these data to inform our final treatment decision.

206 207

In summary, CDI is an increasingly common problem particularly in complex

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hospitalized patients, with few currently available treatment options. Resistance to

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standard therapies is reported to be rising, however limited availability of

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antimicrobial susceptibility testing and sporadic epidemiologic surveillance data

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makes it difficult to know true rates. Extraintestinal infection is well described, but

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remains uncommon. We have described a patient infected with a novel strain of C.

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difficile, who developed severe extraintestinal infection in the setting of recent FMT.

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This recurred despite a 3-month course of appropriate therapy, and eventually

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responded to directed therapy informed by susceptibility testing. Clinicians should

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be aware of this possible complication and the complexities around treatment, with

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prolonged durations of therapy potentially required to achieve cure.

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Figure legend

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Figure 1: Computed tomography (CT) images showing the abdominal collections at

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the time of initial presentation (Panel A). Gram stain of the abdominal fluid revealed

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Gram positive rods (Panel B). Another CT scan at the time of relapse demonstrates a

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large right sided pleural effusion (Panel C).

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Figure 2: Representative timeline of major clinical events including initial diagnosis,

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interventional procedures, positive cultures and antimicrobial therapy. Numbers

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represent days from diagnosis of initial intestinal C. difficile infection.

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Figure 3: Phylogenetic relationship of six reference strains and the isolates in this

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study based on concatenated sequences of 582 non-recombining, core C. difficile

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genes (neighbor-joining dendrogram, Kimura-2 parameter). Ribotypes shown in

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parentheses and boot-strap values shown for all nodes. Accession numbers for

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reference strains/genomes are: CD630 = AM180355, BI9 = FN668944, CD196 =

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FN538970, M68 = FN668375, CF5 = FN665652, M120 = FN665653.

234 235

Acknowledgements: The authors would like to acknowledge Carolina Baez-

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Giangreco and the Tufts Medical Center Microbiology Laboratory for assistance

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processing samples and obtaining isolates, and Dr Laura Kogelman for her input into

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management of the case.

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References [1] D.R. Snydman, L.A. McDermott, N.V. Jacobus, C. Thorpe, S. Stone, S.G. Jenkins, et al. U.S.-Based National Sentinel Surveillance Study for the Epidemiology of Clostridium difficile-Associated Diarrheal Isolates and Their Susceptibility to Fidaxomicin. Antimicrobial agents and chemotherapy 59 (2015) 6437-43. [2] S. Persson, M. Torpdahl, K.E. Olsen. New multiplex PCR method for the detection of Clostridium difficile toxin A (tcdA) and toxin B (tcdB) and the binary toxin (cdtA/cdtB) genes applied to a Danish strain collection. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases 14 (2008) 1057-64. [3] J.N. Martinson, S. Broadaway, E. Lohman, C. Johnson, M.J. Alam, M. Khaleduzzaman, et al. Evaluation of portability and cost of a fluorescent PCR ribotyping protocol for Clostridium difficile epidemiology. Journal of clinical microbiology 53 (2015) 1192-7. [4] A. Bankevich, S. Nurk, D. Antipov, A.A. Gurevich, M. Dvorkin, A.S. Kulikov, et al. SPAdes: a new genome assembly algorithm and its applications to singlecell sequencing. Journal of computational biology 19 (2012) 455-77. [5] Y.B. Chen, S.L. Gu, Z.Q. Wei, P. Shen, H.S. Kong, Q. Yang, et al. Molecular epidemiology of Clostridium difficile in a tertiary hospital of China. Journal of medical microbiology 63 (2014) 562-9. [6] S.L. Gu, Y.B. Chen, T. Lv, X.W. Zhang, Z.Q. Wei, P. Shen, et al. Risk factors, outcomes and epidemiology associated with Clostridium difficile infection in patients with haematological malignancies in a tertiary care hospital in China. Journal of medical microbiology 64 (2015) 209-16. [7] M. He, M. Sebaihia, T.D. Lawley, R.A. Stabler, L.F. Dawson, M.J. Martin, et al. Evolutionary dynamics of Clostridium difficile over short and long time scales. Proc Natl Acad Sci U S A 107 (2010) 7527-32. [8] D.W. Eyre, M.L. Cule, D.J. Wilson, D. Griffiths, A. Vaughan, L. O'Connor, et al. Diverse sources of C. difficile infection identified on whole-genome sequencing. N Engl J Med 369 (2013) 1195-205. [9] L.K. Kociolek, D.N. Gerding, R.O. Espinosa, S.J. Patel, S.T. Shulman, E.A. Ozer. Clostridium difficile Whole Genome Sequencing Reveals Limited Transmission Among Symptomatic Children: A Single-Center Analysis. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America (2018). [10] D.A. Leffler, J.T. Lamont. Clostridium difficile infection. N Engl J Med 372 (2015) 1539-48. [11] L.C. McDonald, D.N. Gerding, S. Johnson, J.S. Bakken, K.C. Carroll, S.E. Coffin, et al. Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA). Clinical Infectious Diseases (2018) cix1085-cix. [12] T.J. Louie, M.A. Miller, K.M. Mullane, K. Weiss, A. Lentnek, Y. Golan, et al. Fidaxomicin versus vancomycin for Clostridium difficile infection. N Engl J Med 364 (2011) 422-31. [13] J.M. Garcia-Lechuz, S. Hernangomez, R.S. Juan, T. Pelaez, L. Alcala, E. Bouza. Extra-intestinal infections caused by Clostridium difficile. Clinical 12

ACCEPTED MANUSCRIPT 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335

microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases 7 (2001) 453-7. [14] E. Mattila, P. Arkkila, P.S. Mattila, E. Tarkka, P. Tissari, V.J. Anttila. Extraintestinal Clostridium difficile infections. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 57 (2013) e14853. [15] A. Gupta, R. Patel, L.M. Baddour, D.S. Pardi, S. Khanna. Extraintestinal Clostridium difficile infections: a single-center experience. Mayo Clinic proceedings 89 (2014) 1525-36. [16] L.E. Wolf, S.L. Gorbach, E.V. Granowitz. Extraintestinal Clostridium difficile: 10 years' experience at a tertiary-care hospital. Mayo Clinic proceedings 73 (1998) 943-7. [17] A.J. Simpson, S.S. Das, S. Tabaqchali. Nosocomial empyema caused by Clostridium difficile. J Clin Pathol 49 (1996) 172-3. [18] A. Deptula, E. Kruszynska, A. Mikucka, E. Gospodarek, K. Olszewski, J. Kruczynski, et al. Toxin A-producing Clostridium difficile as an aetiological factor of post-traumatic wound infection. Journal of medical microbiology 58 (2009) 963-4. [19] E. Urban, G. Terhes, A. Markotics, J. Soki, E. Nagy. Rare extraintestinal infection caused by toxin-producing Clostridium difficile. Anaerobe 16 (2010) 301-3. [20] M. Doufair, C. Eckert, L. Drieux, C. Amani-Moibeni, L. Bodin, M. Denis, et al. Clostridium difficile bacteremia: Report of two cases in French hospitals and comprehensive review of the literature. IDCases 8 (2017) 54-62. [21] J. Gravisse, G. Barnaud, B. Hanau-Bercot, L. Raskine, J. Riahi, J.L. Gaillard, et al. Clostridium difficile brain empyema after prolonged intestinal carriage. Journal of clinical microbiology 41 (2003) 509-11. [22] S. Ranganath, J.K. Midturi. Unusual case of prosthetic shoulder joint infection due to Clostridium difficile. The American journal of the medical sciences 346 (2013) 422-3. [23] A. Al-Najjar, G.N. Al-Rawahi, L.M. Hoang, T.R. Kollmann. Clostridium difficile vertebral osteomyelitis. The Pediatric infectious disease journal 32 (2013) 1030-2. [24] D.W. Eyre, F. Babakhani, D. Griffiths, J. Seddon, C. Del Ojo Elias, S.L. Gorbach, et al. Whole-genome sequencing demonstrates that fidaxomicin is superior to vancomycin for preventing reinfection and relapse of infection with Clostridium difficile. J Infect Dis 209 (2014) 1446-51. [25] J.C. Kwong, N. McCallum, V. Sintchenko, B.P. Howden. Whole genome sequencing in clinical and public health microbiology. Pathology 47 (2015) 199210. [26] D.W. Eyre, A.S. Walker. Clostridium difficile surveillance: harnessing new technologies to control transmission. Expert Rev Anti Infect Ther 11 (2013) 1193-205. [27] C.W. Knetsch, T.D. Lawley, M.P. Hensgens, J. Corver, M.W. Wilcox, E.J. Kuijper. Current application and future perspectives of molecular typing methods to study Clostridium difficile infections. Euro Surveill 18 (2013) 20381.

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ACCEPTED MANUSCRIPT Highlights     

Clostridium difficile is an increasingly common and important clinical problem with relatively limited treatment options Extraintestinal infection has been reported but remains unusual Our case describes a novel strain, with proven recrudescence rather than reinfection, diagnosed with modern molecular techniques New, accurate molecular diagnostic methodologies such as whole genome sequencing are increasingly accessible in near real-time clinical scenarios and allow complex typing questions to be answered more easily Antimicrobial susceptibility testing for anaerobic organisms is difficult to access but important in select cases and for epidemiologic purposes, particularly in era of increasing resistance

ACCEPTED MANUSCRIPT Table 1: Antimicrobial susceptibilities of Clostridium difficile isolates.

Drug

Vancomycin Fidaxomicin Rifaxamin Rifampin Tigecycline Metronidazole Linezolid Imipenem Moxifloxacin Clindamycin Amoxicillin-clavulanate Ampicillin-sulbactam Piperacillin-tazobactam Tetracycline Cefoxitin

Isolate #1, abdominal collection MIC (mg/L) 4 0.5 0.015 ≤0.004 ≤0.12 0.25 1 4 2 4 NP NP NP NP NP

Interpretation

Isolate #2, pleural fluid MIC (mg/L)

Interpretation

R1 n/a R1 n/a S2 S n/a S S I

4 1 0.03 ≤0.004 ≤0.12 0.25 2 4 2 4 4 2 8 0.5 64

R1 n/a R1 n/a S2 S n/a S S I S S S S R

MIC, minimum inhibitory concentration. NP, not performed. S, susceptible. I, intermediate. R, resistant. n/a, not available. CLSI interpretive standards used unless noted. 1MIC > EUCAST ECOFF breakpoint 2MIC < FDA breakpoint