In the case of Clostridium difficile infection, what is the first line treatment?

The first-line treatment for Clostridium difficile infection (CDI) is metronidazole, especially in mild to moderate cases. Metronidazole is an antibiotic that works effectively against the anaerobic bacteria, making it suitable for treating CDI, particularly when the patient's symptoms are not severe.

While vancomycin is also used to treat CDI, it is typically reserved for cases that are severe or if metronidazole has failed. The choice of metronidazole as the initial treatment option, particularly for non-severe episodes, is supported by clinical guidelines due to its efficacy and cost-effectiveness.

Other options such as rifaximin and ciprofloxacin are not standard treatments for CDI. Rifaximin is primarily used for traveler's diarrhea and hepatic encephalopathy, while ciprofloxacin is used for a variety of other infections but does not have established effectiveness against CDI. Thus, metronidazole remains the appropriate first-line treatment for this condition.