Older age , use of antibiotics after diagnosis , use of proton pump inhibitors , and strain type were the most frequent risk factors for recurrence .
Older age , leucocytosis , renal failure and co-morbidities were frequent risk factors for complicated CDI .
When considered alone , mortality was associated with age , co-morbidities , hypo-albuminemia , leucocytosis , acute renal failure , and infection with ribotype 027 .
BACKGROUND Clostridium difficile infection ( CDI ) can lead to complications , recurrence , and death .
Numerous studies have assessed risk factors for these unfavourable outcomes , but systematic review s or meta-analyses published so far were limited in scope or in quality .
Mortality in patients with Clostridium difficile infection correlates with host pro-inflammatory and humoral immune responses.
Host anti-toxin immune responses play important roles in Clostridium difficile disease and outcome . The relationship between host immune and inflammatory responses during severe C. difficile infection ( CDI ) and the risk of mortality has yet to be defined . We aim ed to investigate the host systemic IgG anti-toxin immune responses , the in vitro cytotoxicity of the infecting C. difficile ribotyped strain , and the host inflammatory markers and their relationship to CDI disease severity and risk of mortality . Inflammatory markers , co-morbidities and CDI outcomes were recorded in a prospect i ve cohort of 150 CDI cases .  Serum anti-cytotoxin A ( TcdA ) and anti-TcdB IgG titres were measured by ELISA and the infecting C. difficile isolate was ribotyped and the in vitro cytotoxin titre assessed . A low median anti-TcdA IgG titre was significantly associated with 30-day all-cause mortality ( P<0.05 ) . Ribotype 027 isolates were significantly more toxinogenic than other ribotypes ( P<0.00001 ) . High cytotoxin titres correlated with increased inflammatory markers but also higher anti-TcdA and -TcdB ( P<0.05 ) IgG responses result ing in a lower risk of mortality . On multivariate analysis , predictors of mortality were peak white cell count > 20 × 10(9 ) l(-1 ) [ odds ratio ( OR ) 11.53 ; 95 % confidence interval ( CI ) 2.38 - 55.92 ] , creatinine concentration > 133 µmol l(-1 ) ( OR 6.54 ; 95 % CI 1.47 - 29.07 ) , Horn 's index > 3 ( OR 4.09 ; 95 % CI 0.76 - 22.18 ) and low anti-TcdA IgG ( OR 0.97 ; 95 % CI 0.95 - 0.99 ) , but not ribotype , cytotoxin titre or anti-TcdB IgG. Thus , host pro-inflammatory and humoral responses correlate with the cytotoxin titre of the infecting strain and effective anti-toxin immune responses reduce the risk of mortality
Older age , use of antibiotics after diagnosis , use of proton pump inhibitors , and strain type were the most frequent risk factors for recurrence .
Older age , leucocytosis , renal failure and co-morbidities were frequent risk factors for complicated CDI .
When considered alone , mortality was associated with age , co-morbidities , hypo-albuminemia , leucocytosis , acute renal failure , and infection with ribotype 027 .
BACKGROUND Clostridium difficile infection ( CDI ) can lead to complications , recurrence , and death .
Numerous studies have assessed risk factors for these unfavourable outcomes , but systematic review s or meta-analyses published so far were limited in scope or in quality .