Clostridium difficile outcomes difficult to generalize

The carrier effect, in which up to 20% of hospitalized patients can be chronic carriers of C. difficile, can affect results [2]. Unfortunately, chronic carriers are not identified. Furthermore, the 72-hour cutoff for ICU-acquired C. difficile seems somewhat arbitrary as it can be acquired faster and some patients were admitted to the ICU within the first 72 hours of hospital exposure [3]. In addition, variance in the first-line treatment of acquired CDI and its effect on treatment outcomes is unreported. Also, the detection immunoassay used a sensitivity well below (80%) those of the widely available cytotoxin neutralization assay (96%) and toxigenic culture (100%) [4]. Next, it is unclear whether the two populations were equally sick. The (younger) patients with diarrheal C. difficile were mechanically ventilated longer and received more proton pump inhibitors. Accordingly, unreported severity descriptors such as leukocytosis or renal insufficiency could influence mortality outcomes. Furthermore, total hospital length of stay should be compared since C. difficile diarrhea alone does not necessitate admission to the ICU. The retrospective cohort trial is appropriate, but testing stronger strains of C. difficile, using higher-sensitivity detection methods, and tracking the entire length of stay would more accurately support the authors' conclusions.Jean-Ralph Zahar and Jean-Fran？ois TimsitWe thank Nagella and colleagues for their kind comments about our study [1] and would like to address some of the issues they raise. As they pointed out, up to 20% of hospitalized patients can be chronic carriers. However, we wish to emphasize that, to avoid this bias, we restricted our study to patients with a new ICU-acquired CDI. We selected patients with CDI acquired after 72 hours as the exposed population. We agree that this arbitrary cut-point may have slightly decreased the incidence of ICU-acquired CDI. As stated by Zar and colleagues [5], vancomycin is the treatment of cho