Postoperative infection is one of the most common complications in liver transplant recipients. In our current study, the incidences of bacterial and fungal infections were 14.01% and 4.35%, which were lower than previous reports[19-21
]. We suggested this difference may be related to the different definition of infection. In current study, only culture-positive infections were included. Consistent with previous studies, gram-negative bacteria, especially Enterococcus faecium
and Escherichia coli
, were the predominant bacterial pathogens, whereas Candida albicans
was the most common fungal pathogen[22
Postoperative bile leak was an independent risk factor for bacterial infection of LDLT in current study. This risk factor was not considered in some studies following deceased donor liver transplantation (DDLT)[23
]. This difference was related to the low incidence of postoperative bile leak in patients underwent DDLT. However, bile leak was one of the most common complications in LDLT recipients. This factor should not be ignored in LDLT. Patients with postoperative bile leak suffered from longer abdominal drainage which may increase the risk of intraabdominal and wound infection[24
]. Additionally, bile leak can cause biloma that often progress to an infected abscess[25
It was interesting that patient more than 45 years old was a risk factor related to postoperative bacterial infection. We acknowledge the cut-off value of recipient age was so young in our study. The mean recipient age in current study was 42.93 ± 8.77 years. This was a potential explanation. Similar to our results, Nayaranan et al[26
] suggested patient’s age greater than 42 years old was significantly associated with a poor long-term survival. This finding suggested the incidence of postoperative bacterial infection may be increased with the increasing of recipient age.
Preoperative diabetes mellitus didn’t increase the risk of postoperative infection in our study. However, John et al[27
] suggested pretransplant diabetes was associated with increased postoperative morbidity and mortality. Recently, Ling et al[28
] confirmed preexisting diabetes was not a contraindication for liver transplantation. Well controlled pretransplant diabetes will not increase the risk of postoperative complication. In our practice, the nine patients with pretransplant diabetes had normal blood sugar level at the time of transplantation. Contrary to pretransplant diabetes mellitus, severe postoperative hyperglycemia was an independent risk factor for bacterial infection in current study. However, after transplantation, the administration of immunosuppressive agents, including cyclosporine, steroids and tacrolimus, may cause postoperative hyperglycemia. Ata et al[29
] confirmed postoperative hyperglycemia was the most important risk factor for surgical site infection in general surgery patients. Rueda et al[30
] reported hyperglycemia will increase the risk for and severity of pneumonia among non-diabetic patients.
It was easy to understand prolonged ICU stay and hyponatremia were associated with postoperative bacterial infection. Mnatzaganian et al[31
] confirmed the incidences of bloodstream and urinary infections of patients in ICU were higher than those in regular ward. Suljagic et al[32
] confirmed the incidence of nosocomial bloodstream infection of ICU patients was higher than non-ICU patients. Stormont et al[33
] confirmed hyponatremia was associated with pneumonia. Zilberberg et al[34
] suggested hyponatremia was associated with worsened clinical outcomes among patients with pneumonia.
Although the relationship between massive RBCs transfusion and bacterial infection was well established in previous studies, there were little information of the correlation of massive RBCs transfusion and fungal infection. Current study suggested massive RBCs transfusion will increase the risk of fungal infection after liver transplantation. Blood transfusion can cause transfusion-related immunomodulation which will suppress the recipient’s immune function[35
]. However, it remains unclear why massive transfusion was not a risk factor for bacterial infection in current study.
Postoperative bacterial infection showed significantly prognostic power for fungal infection in current study. Antibiotics, especially broad-spectrum antibiotics, were administrated to patients with bacterial infection in the case of lacking culture results. Broad-spectrum antibiotics might lead to dysbacteriosis and increase fungal infection[36
]. However, a recent study which was performed by Nafady-Hego et al[37
] suggested bacterial infection was not a risk factor for fungal infection after pediatric LDLT. Younger recipient age, lower dosages of immunosuppressive agents and different infection prophylaxis might be the potential explanation for this difference.
In conclusion, preoperative hyponatremia, recipient age > 45 years, longer ICU stay, postoperative bile leak and severe hyperglycemia may be related to postoperative bacterial infection, whereas massive intraoperative RBCs transfusion and postoperative bacterial infection may lead to postoperative fungal infection. Current finding suggested postoperative bacterial and fungal infections were associated with pre-, intra- and post-operative factors.