Multidrug-resistant gram-negative bacterial infections after liver transplantation - spectrum and risk factors

Gram-negative bacilli infections, especially multidrug-resistant gram-negative bacilli infections, are the leading cause of high mortality after liver transplantation. This study sought to investigate the type of infection, infection rate, pathogenic spectrum, antibiotic-resistance profile, risk factors, and epidemiology of multidrug-resistant gram-negative bacterial infection.

A retrospective cohort study was conducted and data of 217 liver transplant patients receiving cadaveric livers between January 2007 and April 2010 were analyzed. Antibiotic susceptibility was determined by minimum inhibitory concentration test. Extended-spectrum and metallo-β-lactamase assays were used to analyze β-lactamase-produced isolates, and repetitive-sequence polymerase chain reaction was used to differentiate bacterium subspecies.

Sixty-seven isolates of multidrug-resistant gram-negative bacteria were isolated from 66 infected liver transplant patients. Stenotrophomonas maltophilia (100%, 8/8), Klebsiella pneumoniae (61.5%, 8/13), Enterobacter cloacae (75%, 3/4) and Escherichia coli (81.3%, 13/16) were the most common extended-spectrum β-lactamase-producing bacilli. Metallo-β-lactamase expressing isolates were identified as S. maltophilia (100%, 8/8), Pseudomonas aeruginosa (83.3%, 5/6), Acinetobacter baumannii (95%, 19/20). Significant independent risk factors for multidrug-resistant gram-negative infection were extended use of pre-transplant broad-spectrum antibiotics (OR 9.027, P=0.001) and prolonged (≧72h) endotracheal intubation (OR 3.537, P=0.033).

To reduce the risk of acquiring MDR gram-negative bacillus infections after liver transplant, control measures are required to limit the use of prophylactic antibiotic in preventing infection during liver transplant and to shorten endotracheal intubation time.