Infections After Heart Transplantation: Incidence, Characters, And Risk Factors

[Objective]Infections are the most common complications afflicting heart transplantation recipients and recognized as the second prominent cause for early death. Detailed information on timetable and the etiology of the infections is helpful to clinical strategy,meanwhile;research on the risk factors of developing infectious complications can tell us how to modify such risk factors to reduce the development of infections.We carried this study to determine the incidence and the etiology of infection complications, to analyze the risk factors of hospital-acquired pneumonia and tracheobronchitis.[Methods]We conducted a retrospective study on the survival heart transplant recipients from 2000 to 2007 who were followed up until January 31^st 2008.(1)Schedule tables were made to record the detail information of each HTs to investigate the demography of the patients compromising the study,the incidence of various infections, the timetable of infections,the etiology of infection complications,drug sensitivity of main causative pathogens,the clinical characters of pneumonias,risk factors influencing the incidence of hospital-acquired pneumonia and tracheobronchitis and mortality of such patients.(2) Continuous variables were expressed as the mean for those with a normal distribution,and as the median.Discrete variables were expressed as percentages. Student's unpaired t-test was used to compare continuous variables,the Mann-Whitney U-test to compare continuous variables with non-normal distribution,and the chi-squared or Fisher exact test to compare proportions.All statistical tests were two-tailed and the threshold of statistical significance was p＜0.05.Relative risks(RRs) were calculated for variables with statistically significant differences between patients with or without LI. Binary logistic regression was applied individually to each variable to obtain the OR in the univariate analysis.[Results](1) A total of 99 recipients were reviewed(heart transplant n=2,heart lung transplant n=97).73(73.7%) patients were male and 26(26.3%) were female.Their ages range from 10 to 76 with a mean of 44.The members compromising the study had different underlying diseases;the most common one was dilated cardiomyopathy (51/51.1%).Acyclovir was administered in 76(76.8%) recipients,acyclovir in 2(2.0%) recipients,and 17 patients didn't receive any prophylactic drugs against CMV infection that underwent their transplant operation before December 2003.Prednisone, Cyclosporine and Mycophenolate consist the anti-rejection therapy strategies in 94(94.9%) cases.(2) 54 heart transplant recipients had 77 episodes of infections.The incidence of infections was 24.5-54.5 episodes per 100 HTs(the total number of HTs was 220).The main infectious complications were blood stream infections(33.8%), pneumonias(24.7%),and urine tract infections(23.4%).Also one of the HTs developed supine tuberculosis,one had HBV infection,one had infectious diarrhea,and one had organ/space surgical site infection.83.1%of the infections occurred in the first month after transplantation.(3) 91 causative microorganisms of 77 cases were identified,77.1% of them were bacteria,14.6%were fungi,and 3 cases were virus(CMV n=2,HBV n=1). 67.6%of bacteria infections were due to Gram-negative bacilli which including enterobacter(34.0%) and non-zymophyte(66.0%).Stenotrophomonas maltophilia (36.3%) and Acinetobacter baumannii(27.2%) were the main species of non-zymophyte bacteria.Escherichia coli(41.2%) and Klebsiella species(35.3%) were the most frequently identified enterobacter.Streptococcus aureus(29.2%) and Enterococcus (25.0%) were the most common Gram-positive coccus species.Yeast(6.6%) and Aspergillus(5.1%) also were identified among these cases.(4) MRSA took 85.7% account of Staphylococcus aureus isolates.(5) The incidence of CMV infections was only 2.0 episodes per 100 HTs in this study.(6) Aspergillus was the second prominent pathogens identified in this group patients.The incidence of invasive pulmonary disease was 5.1 episodes per 100 HTs.(7) Risk factors influencing hospital-acquired pneumonia and tracheobronchitis were analyzed:APACHEâ…¡score of HTs during 24-48 hours after transplantation more than 6 hours(x²=10.26 p=0.01) and invasive ventilation more than 24 hours(x²=13.18 p=0.00).(8) Risk factors associated with the worst prognosis of HTs who have respiratory tract infection were analyzed:Ventilation-acquired pneumonia (p=0.04).[Conclusion](1) 54 heart transplant recipients had 77 episodes of infection.The overall incidence of infection was 24.5-54.5 episodes per 100 HTs.(2) More than 80 percent of the infections occurred in the first month after transplantation.(3) After the first month, the immunomodulating virus CMV began to exert clinical events.Infections due to CMV may be underestimated,but infections caused by Aspergillus species were diagnosis properly.(4) 85.7%of the Staphylococcus aureus were MRSA isolates. Multidrug-resistant non-zymophyte species were prevalent.(5) Both APACHEâ…¡score of HTs during 24-48 hours after transplantation more than 6(RR=5.98) and invasive ventilation more than 24 hours(RR=4.82) were risk factors influencing hospital-acquired pneumonia and tracheobronchitis.(6) Ventilation-acquired pneumonia was the only identified risk factor influencing the prognosis of HTs who have respiratory tract infection.