No genetic testing will be performed on any of the samples being obtained. The biologic samples will be under the control of the principal investigator of this research project. To protect confidentiality, all personal identifiers (i.e., name, social security number, and birth date) will be removed (de-identified) and replaced with a specific code number. The information linking these code numbers to the corresponding subjects' identities will be kept in a separate, secure location. The investigators on this study will keep the samples indefinitely. If a subject withdraws and provides the request in writing, samples collected and not already processed will be destroyed. All samples will be kept in the investigator's laboratory located in Scaife Hall, Room 812, 3550 Terrace Street.
Bacterial cultures will be ordered in the normal clinical course of the management of patients in the liver transplant ICU by the medical team. These cultures are then processed by the clinical Microbiology laboratory in the normal manner. If these cultures grow a Gram-negative bacteria, they are eligible for this study. Typically the clinical Microbiology laboratory saves these bacteria for a period of time after the final microbiology report. At this time, unless asked otherwise, the bacteria will be placed in biohazardous waste containers for proper disposal. If these cultures have grown a Gram-negative bacteria, they are eligible for this study, and will not be disposed of but will be given to the investigators without identifiers for this study. The antibiotic susceptibility of these organisms will be tested by the investigators in a separate research laboratory. Mechanisms of antibiotic resistance may also be assessed.