Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
1 Impact of malignancy on Clostridium difficile infection 2 3 4 Min Sung Chung*, Jieun Kim*, Jung Oak Kang, Hyunjoo Pai 5 6 7 * These authors contributed equally to this work. 8 Min Sung Chung 9 Department of Surgery, Hanyang University College of Medicine, 222-1, 10 Wangsimni-ro, Seongdong-gu, Seoul, Korea 11 E-mail : [email protected] 12 Jieun Kim 13 Department of Internal Medicine, Hanyang University College of Medicine, 14 222-1, Wangsimni-ro, Seongdong-gu, Seoul, Korea 15 E-mail : [email protected] 16 Jung Oak Kang 17 Department of Laboratory Medicine, Hanyang University College of Medicine, 18 222-1, Wangsimni-ro, Seongdong-gu, Seoul, Korea 19 E-mail : [email protected] 20 Hyunjoo Pai (Corresponding author) 21 Department of Internal Medicine, Hanyang University College of Medicine 22 222-1, Wangsimni-ro, Seongdong-gu, Seoul, Korea 23 TEL: +82-2-2290-8356 24 FAX: +82-2-2298-9183 25 E-mail: [email protected] 26 1 27 28 29 30 31 ABSTRACT Purpose: The purpose of the study was to investigate the impact of malignancy and chemotherapy on the clinical and microbiological characteristics of Clostridium difficile infections (CDI). Methods: CDI patients with a history of malignancy within 5 years were defined as the cancer group. The characteristics of the patients were compared according to the presence of malignancy. 32 Results: Of 580 patients with CDI, 159 (27.4%) belonged to the cancer group and 421 (72.6%) to the non- 33 cancer group. More of the patients in the cancer group than of those in the non-cancer group had been hospitalized 34 within the prior 2 months (P<0.001). Leukocytosis was more common in the non-cancer group (P = 0.034), while 35 infection by PCR ribotype 017 strains was more common in the cancer group, with marginal significance (P = 36 0.07). Recurrence was more frequent in the cancer group (20.4% vs. 9.5%, P =0.005) and cancer was an 37 independent risk factor for recurrence of CDI (OR=2.66, 95% CI 1.34-5.29, P =0.005). Age also contributed to 38 the recurrence of CDI (OR=1.03, 95% CI 1.00-1.06, P =0.026). 39 Conclusions: Malignancy and age are independent risk factors for recurrence of CDI. Cancer patients require 40 careful observation for recurrence after treatment of CDI. 41 42 43 Keywords: Clostridium difficile, Malignancy, Clinical outcome, Recurrence 44 45 46 47 48 49 50 51 52 53 54 2 55 INTRODUCTION 56 Clostridium difficile infection (CDI) is the most common cause of healthcare-associated diarrhea [1]. Due to 57 the increased incidence of CDI, mortality, morbidity, length of hospital stay, and healthcare costs have increased 58 [2]. 59 The use of antimicrobial agents is the best-recognized risk factor for CDI [3]. Other risk factors include advanced 60 age, admission to a healthcare facility, severe comorbidities, exposure to chemotherapy, immunosuppressive 61 therapy, and use of proton pump inhibitors [4]. 62 The incidence of CDI in cancer patients receiving chemotherapy has been reported to be as high as 7%, compared 63 to 1–2 % in the general hospitalized population [5-7]. Cancer patients have multiple risk factors for CDI including 64 long-term hospitalization, exposure to broad-spectrum antibiotics, neutropenia, and chemotherapeutic agents. In 65 addition, cancer affects an increasingly elderly population, often affected suffering from multiple co-morbidities 66 [8]. There have been a few studies of CDI in cancer patients but most were of cancer patients receiving 67 chemotherapy or of hematopoietic stem cell transplant patients in single hematology/oncology departments [9-11] 68 or single cancer cohorts [12,11]. 69 To investigate the impact of malignancy and chemotherapy on CDI, we have compared the clinical and 70 microbiological characteristics and clinical outcomes of CDI in cancer and non-cancer patients and in cancer 71 patients receiving or not receiving chemotherapy. 72 73 MATERIALS AND METHODS 74 Setting and study design 75 This study was conducted at Hanyang University Hospital, a 900-bed tertiary care facility located in Seoul, 76 South Korea. From February 2009 through January 2013, patients above 18 years with healthcare-associated C. 77 difficile infections (HA-CDIs) were enrolled. Only the first episode of HA-CDI was included. The study was 78 approved by the institutional review board of Hanyang University Hospital (HYUH IRB 2013-07-016), and 79 informed consent was waived. 80 81 Definitions 82 Diarrhea was defined as unformed stool more than 3 times per day on consecutive days, or 6 times within 36 83 hr. CDI was defined when the isolates from stool cultures were positive for toxin genes (tcdA, tcdB, cdtA, or cdtB) 84 by multiplex PCR, positive in assays for toxins A & B with a commercial kit (VIDAS® C. difficile Toxin A & B; 85 BioMerieux SA, Marcyl’Etoile, France), and/or pseudomembranes were observed during endoscopy or histology. 86 CDI patient who developed diarrhea at least 72 hr after hospitalization or within 2 months of their last discharge 87 were considered as HA-CDI [13]. Those with a history of malignancy within 5 years were defined as the ‘cancer 3 88 group’, and, within the cancer group, patients who received chemotherapy within 2 months were defined as the 89 ‘chemotherapy subgroup’ and those not receiving chemotherapy as the ‘conservative group’. 90 Neutropenia was defined when the WBC count was < 1,000 cells/mm3. Recurrence was defined as growth of C. 91 difficile (as defined above) with resurgence of symptoms, at least 10 days and < 60 days after the first episode 92 [14]. Death related to CDI was defined as death within 30 days after diagnosis if CDI was either the primary or a 93 contributory cause [15]. 94 White blood cell (WBC) count and albumin level were checked within 24 hr of enrollment to assess disease 95 severity. To assess disease severity, two method was applied. Age > 60 yr, temperature > 38.3°C, albumin level < 96 2.5 mg/dL, or WBC count > 15,000 cells/mm3 got 1 point each; the sum of the points was taken as the severity 97 score for CDI and the CDI was considered to be severe when scores were ≥ 2 points [16]. The other method 98 defined by SHEA/IDSA, and white blood cell count ≥ 15,000 cells/mL or serum creatinine ≥1.5 times the 99 premorbid level was regarded as severe CDI [17]. 100 101 Collection of data 102 Age, sex, body mass index (BMI), length of stay in hospital, admission history and medication history within 103 the previous 2 months, and underlying disease including Charlson’s score were obtained as demographic and 104 clinical data by review of medical records. Use of antibiotics and chemotherapy within 2 months has been studied 105 as a risk factor for CDI [18]. We also noted whether antibiotics for non-CDI were continued or discontinued after 106 diagnosis of CDI. 107 108 Isolation and characterization of C. difficile isolates 109 Stool specimens were grown anaerobically on cycloserine–cefoxitin–taurocholate agar (Oxoid Ltd., Cambridge, 110 UK) supplemented with 7% horse blood after alcohol shock treatment [19]. Colonies of C. difficile were identified 111 with an API® Rapid ID 32A system (bioMérieux SA, Lyon, France). Using DNA from each isolate, multiplex 112 PCR for toxin genes and agar gel electrophoresis were performed as described elsewhere with minor modifications 113 [20]. PCR-ribotyping was also performed as described [21]. 114 115 Statistical methods 116 SPSS version 21.0 for Windows (SPSS, Chicago, IL, USA) was used for statistical analysis. Categorical 117 variables were analyzed by Pearson’s chi-square test or Fisher’s exact test. Continuous variables were analyzed 118 by independent t-test or the Mann-Whitney U-test. A P value of < 0.05 in a two-tailed test was considered 119 statistically significant. 4 120 121 122 123 RESULTS During the study period, 580 cases were diagnosed as initial, non-recurrent HA-CDI. 159 cases (27.4%) were in the cancer group and 421 (72.6%) in the non-cancer group. 124 125 Characteristics related to malignancy in the cancer group 126 Of the 159 cancer cases, 144 (90.6%) had solid malignancies and 15 (9.4%) had hematologic malignancies. 127 The most common type of solid malignancy was gastrointestinal (76, 52.8%), followed by pulmonary (27, 18.8%), 128 urologic (10, 6.9%), gynecologic (6, 4.2%), head and neck (5, 3.5%) and breast (4, 2.8%). Sixty-nine of the 159 129 patients (43.4 %) received chemotherapy. The most commonly employed regimens were platinum (35, 50.7%) 130 followed by 5-FU/5-FU prodrugs (18, 26.1%), topoisomerase inhibitors, and taxane and tyrosine kinase inhibitor 131 (TKI)-based regimens used in combination. 132 133 Demographic and clinical characteristics of the CDI patients 134 Table 1 presents the demographic and clinical characteristics of the CDI patients according to presence of 135 malignancy. Age, BMI, and antibiotics history were similar in the two groups. In the cancer group, there were 136 significantly fewer females (P=0.009), more patients were hospitalized within the previous 2 months (45.3% vs. 137 27.4%, P <0.001), and the mean Charlson`s score was significantly higher. Median WBC counts was higher in 138 the non-cancer group (8,000/mm3 vs 9,900/mm3, P<0.001), as was leukocytosis (13.2% vs. 20.9%, P = 0.034). 139 Other factors reflecting disease severity such as old age, fever, and hypoalbuminemia did not differ. 140 Pseudomembranous colitis was observed during endoscopy in 26.3% (10/38) and 38.0% (41/108) of the cancer 141 and non-cancer patients, respectively. 142 The patients in the conservative treatment subgroup were on average older than those in the chemotherapy 143 subgroup (p<0.001) (Table 1). Admissions were more frequent in the chemotherapy subgroup (p=0.005), but 144 antibiotic exposure was more frequent in the conservative subgroup (p=0.004). Higher WBC counts and lower 145 albumin levels were observed in the conservative subgroup (p<0.001, p=0.023, respectively), but there was no 146 difference in severity score. A similar proportion of the patients in each group were treated. 147 148 Clinical outcomes 149 The clinical outcomes of CDI were compared in those cancer and non-cancer patients receiving treatment for 150 CDI (93 and 274 patients, respectively), and between the chemotherapy and conservative subgroups who received 151 treatment for CDI (38 and 55, respectively) (Table 2). 152 Of the 367 treated patients, 22 (6.0%) received vancomycin as first line therapy (3.2% in the cancer vs. 6.9% in 5 153 the non-cancer group; P=0.193). The recurrence rate was significantly higher in the cancer group than the non- 154 cancer group (20.4% vs. 9.5%, P=0.005). Although not statistically significant, the cancer patients had a higher 155 in-hospital mortality rate (23.9% vs. 8.0%, P=0.161); however, CDI-related deaths were more frequent in the non- 156 cancer group (0 vs. 1.8%, P=0.335). 157 158 There were no statistically significant differences in clinical outcomes including recurrence rate between the cancer subgroups. 159 160 Microbiologic characteristics 161 PCR-ribotyping was performed on 400 of 421 isolates (95%) from the non-cancer group and 150 of 159 isolates 162 (94.3%) from the cancer group (Table 1). In the non-cancer group, PCR-ribotype 018 was the most frequent type, 163 whereas, PCR ribotype 017 was the most common type in the cancer group; the latter appeared to be more 164 common in the cancer group than the non-cancer group (P=0.07). A total of 15 binary toxin-producing strains 165 were identified, 2 in the cancer group and 13 in the non-cancer group; one of the strains was PCR ribotype 267 166 and the others had no matching reference strains. PCR ribotype 027 was not encountered. 167 168 There was no statistically significant association between PCR ribotype and toxinotype and exposure to chemotherapy. 169 170 Risk factors for recurrence of CDI 171 In a univariate analysis there was a significant difference between the recurrence rates in the cancer and non- 172 cancer group (Table 1). We therefore performed a multivariate logistic regression analysis to establish whether 173 presence of malignancy remained a risk factor for recurrence after adjusting other variables. Age, sex, history of 174 malignancy, admission history and leukocytosis were included in the analysis. Because of multicollinearity 175 between malignancy and Charlson’s score, we excluded the latter from the analysis. Presence of malignancy 176 within 5 years was found to be a significant risk factor for recurrence (OR=2.665, 95% CI 1.343-5.289, P=0.005). 177 Age also had a statistically significant effect (OR=1.032, 95% CI 1.004-1.060, P=0.026) (Table 3). 178 179 DISCUSSION 180 181 In this study the clinical characteristics, outcomes and microibiological characteristics of CDI in patients with 182 malignancies and those receiving anticancer chemotherapy were investigated. Recurrence of CDI was more 183 frequent in the cancer patients than in the non-cancer patients, but chemotherapy did not significantly effect the 184 clinical outcomes. 185 With regard to CDI in cancer patients, either cancer itself or anticancer chemotherapy could influence the course 186 of CDI. Chemotherapeutic agents could induce colonic inflammation, decrease the repair capacity of the mucosal 187 epithelium or promote an anaerobic enviroment, which favors CDI [7]. In a review of CDI in cancer patients, it 188 was noted that several specific chemotherapeutic agents such as 5-fluorouracil, DNA topoisomerase inhibitors, 189 cisplatin, paclitaxel, and carboplatin among others were associated with the occurrence of CDI [7,22]. In a 6 190 previous study, patients with gastrointestinal cancer had a lower probability of developing CDI than patients with 191 other types of cancer [9]. Because the present study was retrospective, we could not estimate the true incidence 192 and prevalence of CDI in the varios types of cancer or in response to chemotherapy. However, most of the cancer 193 patnts in this study had solid tumors, and gastrointestinal cancer was actually the most common (47.8%) type 194 among the CDI patients. 195 There were no differences between the groups in clinical characteristics. Although WBC count was higher in the 196 non-cancer group than the cancer group, and in the subgroup receiving conservative treament than in the subgroup 197 receiving chemotherapy, severity scores and mortality did not differ between the groups. There were a total of 9 198 neutropenia patients and most of them received chemotherapy, but neutropenia followed by chemotherapy was 199 not associated with a poor outcome of CDI. Therefore, in the cancer group, and especially in the cancer patients 200 receiving chemotherapy, leukocytosis did not predict the clinical course of CDI, which supports the view that 201 other factors influence the CDI severity score in cancer patients [10]. 202 The estimated recurrence rate of CDI among initially treated CDI patients has been reported to be as high as 203 35%, and this increases in the case of hypervirulent BI/NAP1/027 C. difficile infections [23-25]. The recurrence 204 rate in Korea, where the prevalent PCR ribotypes are 017 and 018, has been reported to be 10-20%, lower than in 205 Europe or North America [26,27]. In this study, recurrence was defined as a second episode at least 10 days and 206 no more than 60 days after the first one. The overall recurrence rate was 12.3%, and 20.4% of cancer patients 207 experienced recurrence. The risk factors for recurrent CDI described in previous studies include inadequate 208 antitoxin antibody response, persistent disruption of colonic flora, age over 65 years, continuation of non- 209 C.difficile antimicrobial therapy, long hospital stay, and concomitant receipt of antacid medication [28]. The 210 presence of severe underlying disease was also associated with an increased risk of recurrence [29]. In our study, 211 malignancy itself was found to be an independent risk factor for recurrent CDI regardless of exposure to 212 chemotherapy within 2 months, or hospital admission. The profound immunological changes associated with 213 cancer itself may increase the risk of recurrence [30,31,7]. 214 PCR ribotype 017 strains were the most common C. difficile ribotype infecting cancer patients. These strains are 215 toxin A-negative and toxin B-positive strains endemic in Korea, especially in healthcare settings [32]. Frequent 216 hospitalization probably increased the chance of infection by endemic C. difficile strains, but chemotherapy itself 217 did not favor the acquisition of any particular C. difficile PCR ribotype. Because PCR ribotype 017 infections are 218 reported to be more likely to recur in Korea than other PCR ribotype infections [33], infection by this ribotype 219 may contribute to the higher recurrence rate in cancer patients. 220 This study has several limitations. Because it was retrospective, we could not investigate the incidence of CDI 221 among the totatality of cancer patients admitted to our hosipital, or establish which type of cancer or chemothrapy 222 was most frequently associated with CDI. Second, because the study was conducted in a single-center, the types 223 of cancers in patients and the prevalent strains of C. difficile could differ between hospitals, and conclusions must 224 be generalized with care. However, our findings provide a basis for larger multicenter prospective studies of CDI 225 in patients with malignancies. 226 227 In conclusion, malignancy and old age are independent risk factors for recurrence of CDI. CDI patients suffering from cancer should be kept under careful observation for recurrence after the initial treatment. 228 7 229 Acknowledgments 230 Funding : none 231 Conflict of Interest : none 232 Ethical approval : approved by the institutional review board of Hanyang University Hospital (HYUH IRB 2013- 233 07-016) 234 Informed consent : waived. 235 Parts of this study present as a poster at ASM microbe 2016 (poster number 2207, June 16-20, 2016, Boston, US) 236 237 REFERENCES 238 239 1. Kelly CP, LaMont JT (2008) Clostridium difficile--more difficult than ever. The New England journal of 240 medicine 359 (18):1932-1940. doi:10.1056/NEJMra0707500 241 2. Monge D, Millan I, Gonzalez-Escalada A, Asensio A (2013) [The effect of Clostridium difficile infection on 242 length of hospital stay. A cohort study]. Enfermedades infecciosas y microbiologia clinica 31 (10):660-664. 243 doi:10.1016/j.eimc.2012.11.007 244 3. McFarland LV, Mulligan ME, Kwok RY, Stamm WE (1989) Nosocomial acquisition of Clostridium difficile 245 infection. The New England journal of medicine 320 (4):204-210. doi:10.1056/NEJM198901263200402 246 4. Bartlett JG, Gerding DN (2008) Clinical recognition and diagnosis of Clostridium difficile infection. Clinical 247 infectious diseases : an official publication of the Infectious Diseases Society of America 46 Suppl 1:S12-18. 248 doi:10.1086/521863 249 5. Kamthan AG, Bruckner HW, Hirschman SZ, Agus SG (1992) Clostridium difficile diarrhea induced by cancer 250 chemotherapy. Archives of internal medicine 152 (8):1715-1717 251 6. Husain A, Aptaker L, Spriggs DR, Barakat RR (1998) Gastrointestinal toxicity and Clostridium difficile 252 diarrhea in patients treated with paclitaxel-containing chemotherapy regimens. Gynecologic oncology 71 (1):104- 253 107. doi:10.1006/gyno.1998.5158 254 7. Khan A, Raza S, Batul SA, Khan M, Aksoy T, Baig MA, Berger BJ (2012) The evolution of Clostridium 255 difficile infection in cancer patients: epidemiology, pathophysiology, and guidelines for prevention and 256 management. Recent patents on anti-infective drug discovery 7 (2):157-170 257 8. Barnett K, Mercer SW, Norbury M, Watt G, Wyke S, Guthrie B (2012) Epidemiology of multimorbidity and 258 implications for health care, research, and medical education: a cross-sectional study. Lancet 380 (9836):37-43. 259 doi:10.1016/S0140-6736(12)60240-2 260 9. Rodriguez Garzotto A, Merida Garcia A, Munoz Unceta N, Galera Lopez MM, Orellana-Miguel MA, Diaz- 261 Garcia CV, Cortijo-Cascajares S, Cortes-Funes H, Agullo-Ortuno MT (2015) Risk factors associated with 262 Clostridium difficile infection in adult oncology patients. Supportive care in cancer : official journal of the 263 Multinational Association of Supportive Care in Cancer 23 (6):1569-1577. doi:10.1007/s00520-014-2506-7 264 10. Yoon YK, Kim MJ, Sohn JW, Kim HS, Choi YJ, Kim JS, Kim ST, Park KH, Kim SJ, Kim BS, Shin SW, Kim 8 265 YH, Park Y (2014) Predictors of mortality attributable to Clostridium difficile infection in patients with underlying 266 malignancy. Supportive care in cancer : official journal of the Multinational Association of Supportive Care in 267 Cancer 22 (8):2039-2048. doi:10.1007/s00520-014-2174-7 268 11. Krishna SG, Zhao W, Apewokin SK, Krishna K, Chepyala P, Anaissie EJ (2013) Risk factors, preemptive 269 therapy, and antiperistaltic agents for Clostridium difficile infection in cancer patients. Transplant infectious 270 disease : an official journal of the Transplantation Society 15 (5):493-501. doi:10.1111/tid.12112 271 12. Hwang KE, Hwang YR, Seol CH, Park C, Park SH, Yoon KH, Park DS, Lee MK, Jeong ET, Kim HR (2013) 272 Clostridium difficile Infection in lung cancer patients. Japanese journal of infectious diseases 66 (5):379-382 273 13. Gravel D, Miller M, Simor A, Taylor G, Gardam M, McGeer A, Hutchinson J, Moore D, Kelly S, Boyd D, 274 Mulvey M, Canadian Nosocomial Infection Surveillance P (2009) Health care-associated Clostridium difficile 275 infection in adults admitted to acute care hospitals in Canada: a Canadian Nosocomial Infection Surveillance 276 Program Study. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 277 48 (5):568-576. doi:10.1086/596703 278 14. Barbut F, Richard A, Hamadi K, Chomette V, Burghoffer B, Petit JC (2000) Epidemiology of recurrences or 279 reinfections of Clostridium difficile-associated diarrhea. Journal of clinical microbiology 38 (6):2386-2388 280 15. Kuijper EJ, Coignard B, Tull P (2006) Emergence of Clostridium difficile-associated disease in North America 281 and Europe. Clinical microbiology and infection : the official publication of the European Society of Clinical 282 Microbiology and Infectious Diseases 12 Suppl 6:2-18. doi:10.1111/j.1469-0691.2006.01580.x 283 16. Zar FA, Bakkanagari SR, Moorthi KM, Davis MB (2007) A comparison of vancomycin and metronidazole 284 for the treatment of Clostridium difficile-associated diarrhea, stratified by disease severity. Clinical infectious 285 diseases : an official publication of the Infectious Diseases Society of America 45 (3):302-307. 286 doi:10.1086/519265 287 17. Cohen SH, Gerding DN, Johnson S, Kelly CP, Loo VG, McDonald LC, Pepin J, Wilcox MH (2010) Clinical 288 practice guidelines for Clostridium difficile infection in adults: 2010 update by the society for healthcare 289 epidemiology of America (SHEA) and the infectious diseases society of America (IDSA). Infect Control Hosp 290 Epidemiol 31 (5):431-455. doi:10.1086/651706 291 18. O'Connor JR, Johnson S, Gerding DN (2009) Clostridium difficile infection caused by the epidemic 292 BI/NAP1/027 strain. Gastroenterology 136 (6):1913-1924. doi:10.1053/j.gastro.2009.02.073 293 19. Aspinall ST, Hutchinson DN (1992) New selective medium for isolating Clostridium difficile from faeces. 294 Journal of clinical pathology 45 (9):812-814 295 20. Persson S, Torpdahl M, Olsen KE (2008) New multiplex PCR method for the detection of Clostridium difficile 296 toxin A (tcdA) and toxin B (tcdB) and the binary toxin (cdtA/cdtB) genes applied to a Danish strain collection. 297 Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology 298 and Infectious Diseases 14 (11):1057-1064. doi:10.1111/j.1469-0691.2008.02092.x 299 21. Bidet P, Barbut F, Lalande V, Burghoffer B, Petit JC (1999) Development of a new PCR-ribotyping method 300 for Clostridium difficile based on ribosomal RNA gene sequencing. FEMS Microbiol Lett 175 (2):261-266 301 22. Chopra T, Alangaden GJ, Chandrasekar P (2010) Clostridium difficile infection in cancer patients and 302 hematopoietic stem cell transplant recipients. Expert review of anti-infective therapy 8 (10):1113-1119. 303 doi:10.1586/eri.10.95 9 304 23. Maroo S, Lamont JT (2006) Recurrent clostridium difficile. Gastroenterology 130 (4):1311-1316. 305 doi:10.1053/j.gastro.2006.02.044 306 24. Garey KW, Sethi S, Yadav Y, DuPont HL (2008) Meta-analysis to assess risk factors for recurrent Clostridium 307 difficile infection. The Journal of hospital infection 70 (4):298-304. doi:10.1016/j.jhin.2008.08.012 308 25. Marsh JW, Arora R, Schlackman JL, Shutt KA, Curry SR, Harrison LH (2012) Association of relapse of 309 Clostridium difficile disease with BI/NAP1/027. Journal of clinical microbiology 50 (12):4078-4082. 310 doi:10.1128/jcm.02291-12 311 26. Kim J, Pai H, Seo MR, Kang JO (2011) Epidemiology and clinical characteristics of Clostridium difficile 312 infection in a Korean tertiary hospital. Journal of Korean medical science 26 (10):1258-1264. 313 doi:10.3346/jkms.2011.26.10.1258 314 27. Lee JH, Lee SY, Kim YS, Park SW, Park SW, Jo SY, Ryu SH, Lee JH, Moon JS, Whang DH, Shin BM (2010) 315 [The incidence and clinical features of Clostridium difficile infection; single center study]. The Korean journal of 316 gastroenterology = Taehan Sohwagi Hakhoe chi 55 (3):175-182 317 28. Johnson S (2009) Recurrent Clostridium difficile infection: a review of risk factors, treatments, and outcomes. 318 The Journal of infection 58 (6):403-410. doi:10.1016/j.jinf.2009.03.010 319 29. Kelly CP (2012) Can we identify patients at high risk of recurrent Clostridium difficile infection? Clinical 320 microbiology and infection : the official publication of the European Society of Clinical Microbiology and 321 Infectious Diseases 18 Suppl 6:21-27. doi:10.1111/1469-0691.12046 322 30. Bishop KD, Castillo JJ (2012) Risk factors associated with Clostridium difficile infection in adult oncology 323 patients with a history of recent hospitalization for febrile neutropenia. Leukemia & lymphoma 53 (8):1617-1619. 324 doi:10.3109/10428194.2012.654472 325 31. Loo VG, Bourgault AM, Poirier L, Lamothe F, Michaud S, Turgeon N, Toye B, Beaudoin A, Frost EH, Gilca 326 R, Brassard P, Dendukuri N, Beliveau C, Oughton M, Brukner I, Dascal A (2011) Host and pathogen factors for 327 Clostridium difficile infection and colonization. The New England journal of medicine 365 (18):1693-1703. 328 doi:10.1056/NEJMoa1012413 329 32. Kim J, Kang JO, Kim H, Seo MR, Choi TY, Pai H, Kuijper EJ, Sanders I, Fawley W (2013) Epidemiology of 330 Clostridium difficile infections in a tertiary-care hospital in Korea. Clinical microbiology and infection : the 331 official publication of the European Society of Clinical Microbiology and Infectious Diseases 19 (6):521-527. 332 doi:10.1111/j.1469-0691.2012.03910.x 333 33. Kim J, Seo MR, Kang JO, Kim Y, Hong SP, Pai H (2014) Clinical characteristics of relapses and re-infections 334 in Clostridium difficile infection. Clinical microbiology and infection : the official publication of the European 335 Society of Clinical Microbiology and Infectious Diseases 20 (11):1198-1204. doi:10.1111/1469-0691.12704 336 10