Which of the following factors is not related to an increased risk for Clostridium difficile infection?

The factor related to an increased risk for Clostridium difficile infection is largely associated with changes in the gut environment or immune system suppression. Recent surgery, chemotherapy, and prolonged hospitalization are known contributors to this risk due to their impact on gut flora and skin barriers, as well as the likelihood of antibiotic use in these scenarios.

Low vitamin D levels, while having implications for overall health and immune function, do not have a direct correlation with increased risk for Clostridium difficile infection. The infection is primarily linked to the disruption of gut microbiota, often due to antibiotic use, rather than nutritional deficiencies. Thus, factors like recent surgery, which may involve antibiotic prophylaxis, or chemotherapy, which can compromise immune responses and alter the gut flora, are much more significant in this context than low vitamin D, making this the correct choice.