Patient description: The patient is a 3-day-old female infant with jaundice that started one day ago. She was born at 34w of gestation and kept in an incubator due to her gestational age. Vital signs were reported as: axillary temperature: 36.3°C, heart rate: 154 beats/min, respiratory rate: 37 breaths/min, and blood pressure: 65/33 mm Hg. Her weight is 2.1 kg, length is 45 cm, and head circumference 32 cm. She presents with yellow sclera and icteric body. Her liver and spleen are normal to palpation. Laboratory results are as follows: Serum total bilirubin: 21.02 mg/dL Direct bilirubin of 2.04 mg/dL AST: 37 U/L ALT: 20 U/L GGT: 745 U/L Alkaline phosphatase: 531 U/L Creatinine: 0.3 mg/dL Urea: 29 mg/dL Na: 147 mEq/L K: 4.5 mEq/L CRP: 3 mg/L Complete blood cell count within the normal range. She is diagnosed with neonatal jaundice that may require phototherapy.

Clinical trial eligibility criteria: eligible ages (years): 0.0-999.0,  Carbapenem Resistant Bacteria Infection Selection for CRE and CRAB GROUP: (all must be fulfilled) Isolation of CRE or CRAB from a clinical sample (e.g., a sample obtained in the work-up of a patient with suspicion of infection; therefore, screening samples are not considered) The patient meets the for any of the following infections (see definitions below): complicated urinary tract infection, pneumonia, intraabdominal infection or bloodstream infection (if the source of infection is any of the above, the patient will be included in both groups) Patient or his/her representative sign the inform consent if requested by the local Institutional Review Board (IRB). Patients in these groups will be included until the needed sample sizes are reached  The infection is considered to be polymicrobial according to standard microbiological interpretation of culture results (except for cIAI, in which polymicrobial infections are allowed) The patient was participating in a clinical trial that involved active treatment for the infections The patient was previously included in the same cohort of this study for the same organism. A single episode of CRE or CRAB per patient can be included. Patients who suffer a CRE infection could later be included in the CRAB cohort if developing a CRAB infection and vice versa Patients with do not resuscitate orders or with a life expectancy of <30 days. Selection for CSE GROUP (all must be fulfilled) Isolation of CSE from a clinical sample (e.g., a sample obtained in the work-up of a patient with suspicion of infection; therefore, screening samples are not considered) The patient meets the for any of the following infections (see definitions below): complicated urinary tract infection, pneumonia, intraabdominal infection or bloodstream infection (if the source of infection is any of the above, the patient will be included in both groups) The infection is the same as that of the index case; in case of BSI, the source of bacteraemia must be the same as the index case classified as follows: UTI, pneumonia, intraabdominal infection or any other The type of acquisition is the same as for the index CRE case (nosocomial or community) The previous length of hospitalization before the infection onset is minus 1 up to minus 3 days the previous length of hospitalization before the CRE infection date in the CRE correspondent (up to minus 7 days if the CRE case occurred after 14 days of previous stay) The patient was admitted to the same type of service as the index case (medical, surgical, ICU, neonatal Unit, paediatric ICU, general paediatric wards)