In addition, the subcohort with infections by multi-drug resistant organisms and a random 20% of the subcohort with infections by sensitive organisms will be selected for follow-up, consisting of sending questionnaires and renewed medical file review 30 days after the index culture date. In the case of ongoing sequelae of the gram-negative infection, this procedure is repeated 90 days after the index culture date. These questionnaires will feed into the outcomes costs, DALYs and quality-adjusted life years (QALYs).