Infectious Complications among 620 Consecutive Heart Transplant Patients at Stanford University Medical Center

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1 REVIEW ARTICLE Infectious Complications among 620 Consecutive Heart Transplant Patients at Stanford University Medical Center Jose G. Montoya, 1,2 Luis F. Giraldo, 1,2 Bradley Efron, 5 Edward B. Stinson, 4 Pat Gamberg, 4 Sharon Hunt, 3 Nadia Giannetti, 3 Joan Miller, 4 and Jack S. Remington 1,2 1 Department of Immunology and Infectious Diseases, Research Institute, Palo Alto Medical Foundation, Palo Alto; and 2 Division of Infectious Diseases and Geographic Medicine and 3 Division of Cardiovascular Medicine (Department of Medicine), 4 Department of Cardiothoracic Surgery, and 5 Department of Statistics and Biostatistics, Stanford University School of Medicine, Stanford, California A total of 1073 infectious episodes (IEs) that occurred in 620 consecutive heart transplantation patients at Stanford Medical Center between 16 December 1980 and 30 June 1996 were reviewed. Infectious complications were a major cause of morbidity and mortality, second only to rejection as the cause of early deaths and the most common cause of late deaths. Of the IEs, 468 (43.6%) were caused by bacteria, 447 (41.7%) by viruses, 109 (10.2%) by fungi, 43 (4.0%) by Pneumocystis carinii, and 6 (0.6%) by protozoa. The largest number of IEs occurred in the lungs (301 [28.1%]). A significant reduction in the incidence of IEs and a delay in presentation after transplantation were observed; these were most likely related to the introduction of new chemoprophylactic regimens during the study period and prevention of significant disease caused by cytomegalovirus. In 1971, Stinson et al. [1] described the incidence, lifethreatening nature, and clinical challenges of infections that occurred in the first 20 heart transplantation patients at Stanford Medical Center (Stanford, CA). A wide variety of organisms caused these infections, including bacteria, fungi, viruses, and protozoa. Subsequent reports from other transplantation centers confirmed this initial observation [2 7]. These reports also revealed that the rates and types of infectious complications vary among the different centers [8]. Several factors appear to influence the frequency and Received 18 November 1999; revised 12 February 2001; electronically published 6 August Presented in part: the 10th International Symposium on Infections in the Immunocompromised Host, held in Davos, Switzerland, in June Financial support: National Institutes of Health (grant AI04717). Reprints or correspondence: Dr. Jose G. Montoya, Palo Alto Medical Foundation Research Institute, 795 El Camino Real, Ames Bldg., Palo Alto, CA (gilberto@leland.stanford.edu). Clinical Infectious Diseases 2001; 33: by the Infectious Diseases Society of America. All rights reserved /2001/ $03.00 type of infectious complications observed among different populations of heart transplant patients. The most important factor appears to be the nature of the immunosuppressive drugs, their temporal sequence, and the duration of use [9]. Others include geographic differences in and intensity of exposure to community and hospital-acquired organisms and the introduction of preventive antimicrobial strategies for routine use. The purpose of the present study was to assess the overall prevalence of infectious complications in heart transplantation patients at Stanford University Medical Center over a 16-year period and to evaluate the impact of prophylactic antimicrobial strategies on the time of occurrence of the various infectious complications after transplantation. MATERIALS AND METHODS Study population. A total of 620 consecutive patients who underwent orthotopic heart transplantation from December 1980 through June 1996 at Stanford Medical Center were reviewed. Pretransplantation clinical and Infectious Complications of Heart Transplantation CID 2001:33 (1 September) 629

2 demographic information on the transplant recipients and donors, type of immunosuppression, type of perioperative infectious prophylaxis, follow-up clinical information, incidence of rejection episodes that require treatment, and incidence and type of infectious episodes (IEs) were prospectively collected and recorded in a computer database (Stanford Transplant Database). The infections were listed according to type of organism (bacterium, virus, fungus, parasite), location of infection, time of onset of IE after transplantation, and clinical outcome. Serological screening for cytomegalovirus (CMV), Toxoplasma gondii, and hepatitis B antibodies was performed for donors and recipients. HIV and hepatitis C antibody screening has been performed on donors and recipients since 1985 and 1990, respectively. Selection criteria for recipients and donors have been described elsewhere [10, 11] and remained fairly constant over the period of the study, except for the age of the recipients; the initial upper age limit of 50 years has been extended over time for otherwise suitable potential recipients. Immunosuppressive therapy and operative techniques. Each of the 620 patients received standard triple immunosuppressive therapy with cyclosporine, azathioprine, and prednisone. High cyclosporine dosages were used initially (18 mg/[kg/d]), but since 1984, these doses have been reduced in order to prevent nephrotoxicity; cyclosporine therapy was initiated after surgery and titrated to maintain a trough serum concentration of ng/ml in the first few weeks after transplantation and ng/ml thereafter. Azathioprine was reinstituted as a third agent in 1984, and the dosage was adjusted according to the WBC count; it was iv administered at 4 mg/(kg/d) on the day of the operation; after surgery the dosage was changed to 2 mg/(kg/d). The dosage of azathioprine was also adjusted to maintain a WBC count 15000/mm 3. Corticosteroids were administered in tapering doses. Methylprednisolone was administered during surgery (500 mg at the conclusion of cardiopulmonary bypass) and after surgery (125 mg q8h, 3 doses). Prednisone therapy was then started at a dosage of 0.6 mg/(kg/d) and gradually tapered over the next 2 months to 0.2 mg/(kg/d). Polyclonal rabbit antithymocyte globulin (Stanford) and, subsequently, horse antithymocyte globulin (ATGAM; Upjohn) were used from 1980 through Since mid-1987, OKT3 has been used for induction therapy. From mid-1987 to 1995, OKT3 was iv administered (5 mg/d) for 14 days. Since 1995, it has been administered for 7 days. Operative techniques did not change significantly during the study period. Prophylactic regimens. Until 1992, perioperative prophylactic antibiotics included erythromycin and cefamandole. Since 1992, a combination of cefazolin (1.0 g q8h, 6 doses) and erythromycin (1.0 g q6h, 8 doses) has been used. In an attempt to prevent oropharyngeal candidiasis, topical mycostatin troches ( suck and swallow t.i.d.) or suspension (5 cc, swish and swallow t.i.d.) has been used since Since July 1993, in an attempt to prevent invasive aspergillosis, aerosolized amphotericin B (20 mg in sterile water t.i.d.) has been administered throughout the posttransplantation hospital stay. Since 1988, trimethoprim-sulfamethoxazole prophylaxis (1 double-strength tablet b.i.d., 3 times each week) has been used. Monthly pentamidine inhalations were used during the study period for patients who could not tolerate trimethoprimsulfamethoxazole. Since 1987, ganciclovir (5 mg/kg b.i.d. for 2 weeks, then 6 mg/kg each day for 4 weeks) has been administered after transplantation when positive antibody titers for CMV are found in either the recipient or the donor [12]. Since January 1996, in those cases in which the donor is positive and the recipient is negative for CMV antibodies (D /R ), 2 additional weeks of therapy with ganciclovir (6 mg/kg each day) have been given. Since January 1996, D /R patients also have received iv human CMV immunoglobulin (Cytogam; MedImmune) for 16 weeks [13]. Acyclovir was not used for prophylaxis against CMV or herpes simplex virus/varicella zoster virus (HSV/VZV). When the donor was positive and the recipient negative for T. gondii IgG antibodies, a course of 4 6 weeks of postoperative treatment with pyrimethamine (25 mg/d) was used [14]. Posttransplantation surveillance. Sputum cultures were usually performed daily until patients underwent extubation. Urine culture specimens were obtained weekly from most patients during the hospitalization period. Blood culture specimens were drawn when indicated by the presence of fever or suspected infection. Chest radiographs were obtained daily until the transplant recipient s cardiopulmonary status stabilized and 2 3 times weekly thereafter, until discharge from the hospital. If indicated (e.g., by new onset of fever or leukocytosis), culture specimens were obtained by transtracheal aspiration or bronchoscopy or from appropriately targeted systems or organs (e.g., urine, oral ulcers, CSF, wounds). Respiratory specimens (transtracheal aspirates and tissue obtained by bronchoscopy or by transthoracic needle aspiration) were cultured for aerobic and anaerobic bacteria, mycobacteria, fungi, Legionella species, and CMV and examined by gram, acid-fast, methenaminesilver, and direct fluorescent staining for Legionella species. Each recipient was closely observed, either at Stanford Medical Center or in close communication with the primary care physician on an outpatient basis. The recipients underwent yearly detailed evaluations, including routine cardiac catheterization, endomyocardial biopsy, and coronary arteriography, at Stanford Medical Center. Morbid and fatal transplantation-related events were categorized as rejection, infection, and graft coronary artery disease (on the basis of angiographic and/or autopsy findings). The autopsy rate was 190%. 630 CID 2001:33 (1 September) Montoya et al.

3 Definition of infection. The diagnosis of bacterial pulmonary infection required the presence of new or worsening pulmonary infiltrates and growth of organisms in cultures of samples obtained by one of the above-mentioned techniques and was not established in any case by sputum culture alone. Bacterial infections at other sites were diagnosed by routine methods, except for urinary tract infections, which were diagnosed on the basis of the finding of associated symptoms, pyuria, or bacteremia, in addition to a positive urine culture (110 5 bacteria/ml). The diagnosis of fungal infection required histologic evidence of tissue invasion or isolation from blood or an otherwise sterile site. Diagnosis of viral infection required a significant rise in serological test titer (a 4-fold rise in serial serum samples) and/ or 1 of the following: a newly positive IgM antibody titer associated with clinical evidence of disease requiring antiviral therapy; seroconversion; virus isolation; or histopathologic evidence of the virus. CMV pneumonia was diagnosed by the presence of new or worsening pulmonary infiltrates plus CMV inclusion bodies in lung biopsy specimens or the positivity of bronchoalveolar lavage fluid for CMV (in patients whose other diagnostic studies were negative). The isolated finding of a rise in serological test titer without signs or symptoms and not requiring antiviral therapy was not used as a criterion of active viral infection in this study. CMV antigen was not used for diagnosis of CMV disease. Some cases of disseminated HSV infection were diagnosed by amplification of HSV DNA in peripheral blood by means of PCR. Disseminated infection was defined as involvement of 2 sites (in bacterial infections) or by virus isolation or PCRpositive blood (in viral infections). Infections caused by Pneumocystis carinii or T. gondii were diagnosed by characteristic cytological and/or histologic findings. For infections with T. gondii, isolation from tissues or body fluids was attempted; changes in serological test titers alone were not considered diagnostic of active infection [15]. All consecutive IEs in each transplant recipient were included. Mild infections treated in the outpatient setting were not included in the present series. Rejection and its management. Cardiac allograft rejection was detected by routine endomyocardial biopsy [16] or suspected on clinical grounds and confirmed by biopsy in most instances. Moderate or severe rejection was treated with iv methylprednisolone (1 g/d for 3 days), followed by a 2-week prednisone tapering schedule. Rejection resistant to 2 courses of this regimen was treated with antithymocyte globulin or OKT3. Total lymphoid irradiation or administration of methotrexate has been used as adjunctive therapy for more recalcitrant rejection [6]. Statistical analysis. A combination of Kaplan-Meier and Cox proportional hazard analyses were used to examine trends in the incidence of significant IEs and also of death due to infection, rejection, and graft atherosclerosis over the 16-year study period. The IEs that were analyzed included those due to CMV, HSV, VZV, Aspergillus species, Candida species, bacterial infections, Staphylococcus species, Nocardia, Listeria, and Pneumocystis; T. gondii was not included because only 4 cases of toxoplasmosis were observed during the study period. The impact of several prophylactic interventions on the incidence of the IEs was studied by means of survival analysis techniques. To illustrate the effects of prophylactic interventions introduced over the 16-year study period, the incidence of various IEs, as well as death, were estimated as a function of time. The conclusion that a specific prophylactic intervention contributes or does not contribute to an already declining incidence of a given IE is derived from analysis of the data on incidence as a function of time by formal tests for statistical significance and not necessarily from the visual appearances of the curves themselves. RESULTS From 16 December to 30 June 1996, 620 consecutive patients underwent orthotopic cardiac transplantation for endstage heart disease at Stanford Medical Center. The mean age of the patients (recipients) was 40.4 years. The mean age of the donors was 25.4 years. Of the 620 patients, 483 (78%) were men and 137 (22%) were women; 518 (84%) of the 620 were white, 40 (7%) were black, 32 (5%) were Hispanic, 21 (3%) were Asian, and 9 (1%) were of other ethnic groups. Fortyfour patients (7.1%) underwent retransplantation. Diagnosed underlying heart diseases among the recipients included idiopathic cardiomyopathy in 241 (39%), coronary artery disease in 236 (38%), congenital disease in 38 (6%), viral myopathy in 32 (5%), familial myopathy in 23 (4%), valvular disease in 17 (3%), postpartum cardiomyopathy 12 (2%), and graft atherosclerosis in 1. The leading cause of early death (!30 days after transplantation surgery) was rejection, whereas infection was the leading cause of late death (130 days after transplantation surgery; table 1). Infectious episodes, by pathogen. During the study period, 1073 IEs occurred in the 620 patients (rate of IE per patient, 1.73). A total of 468 (43.6%) of the IEs were bacterial, 447 (41.7%) were viral, 109 (10.2%) were fungal (excluding P. carinii), 43 (4%) were P. carinii, and 6 (0.6%) were parasitic infections (table 2). The most common bacterial IEs were pulmonary infections (164 [35%]) and urinary tract infections (114 [24.4%]; table 3). Gram-negative bacteria, most commonly Escherichia coli or Pseudomonas aeruginosa, accounted for nearly 53% of 468 bacterial IEs. Sixty-three (75%) of E. coli infections were in the urinary tract, whereas most P. aeruginosa infections (19 [43%]) Infectious Complications of Heart Transplantation CID 2001:33 (1 September) 631

4 Table 1. Causes of death among 620 heart transplantation patients at Stanford Medical Center between 16 December 1980 and 30 June Cause of death No. (%) of deaths Early (!30 POD) Late (130 POD) Rejection 11 (28) 25 (10) Infection 7 (18) 83 (33) Pulmonary hypertension 7 (18) 1 (0) Nonspecific graft failure 6 (15) 9 (4) Graft atherosclerosis 0 57 (22) CVA 2 (5) 7 (3) LPD 0 13 (5) Non-LPD 0 21 (8) Hemorrhage 1 (3) 2 (1) Other 5 (13) 36 (14) Total NOTE. CVA, cerebrovascular accident; LPD, lymphoproliferative disorder; Non-LPD, malignancy excluding lymphoproliferative disorder; POD, postoperative days. were pulmonary. Gram-positive bacteria (170 IEs), particularly Staphylococcus species, accounted for 36% of 468 bacterial IEs. The coagulase status was known for 51 of 75 staphylococcal isolates: 30 (58.8%) were coagulase-positive (S. aureus) and 21 (41.2%) were coagulase-negative. The majority (75%) of coagulase-negative staphylococcal infections occurred in the bloodstream, whereas focal infections (e.g., abscesses and infections of the mediastinum and lungs) accounted for the majority of S. aureus infections; only 6 (20%) of 30 were identified as bloodstream infections. The most common viral IEs were HSV stomatitis, in 106 (23.7%); shingles, in 112 (25.1%); and disseminated CMV infection, in 63 (14.1%). There were no cases of primary VZV infection (chickenpox). Among the 141 IEs caused by CMV, focal CMV disease occurred more commonly as pneumonia (in 38 [27%]) and gastrointestinal disease (i.e., gastritis or colitis, in 27 [19.2%]); involvement of the retina by CMV occurred in only 5 (3.6%). CMV serological test results were available for 568 donors; 276 (48.6%) of them were positive for CMV-specific IgG antibodies. Results of CMV serological tests were available for 589 recipients; 319 (54.2%) were positive preoperatively. CMV serological test results were available for 556 donor/recipient (D/ R) pairs; of these, 147 (26.5%) were D /R, 137 (24.6%) D / R, 108 (19.4%) D /R, and 164 (29.5%) D /R. CMV disease developed in 4 D /R patients (2.7%), 12 D /R patients (8.8%), 16 D /R patients (9.8%), and 26 D /R patients (24.1%). The most common fungal IEs were pulmonary infections, in 41 (37.6%), and disseminated disease, in 30 (27.5%). Aspergillus species and Candida species accounted for 90 (83%) of the 109 fungal IEs (table 4). Information regarding the implicated species of Aspergillus was available for 35 (64.8%) of the 54 IEs: 30 (85.6%) were A. fumigatus, 3 (8.6%) were A. flavus, 1 (2.9%) was A. terreus, and 1 (2.9%) was A. nidulans. Each of the 43 IEs caused by P. carinii were pulmonary. Twenty-eight (65%) of the 43 occurred in the first 6 months after transplantation, 5 (11.7%) between 6 and 12 months after transplantation, and 10 (23.3%) 11 year after transplantation. The most common IE due to parasites was caused by T. gondii (4 of 6); the other 2 IEs were due to intestinal giardiasis and vaginal trichomoniasis. Results of serological testing for Toxoplasma were available for 582 donors (35 [6%] had T. gondii specific IgG antibodies) and 607 recipients (98 [16.1%] were positive). Results of serological testing for Toxoplasma were available for 575 D/R pairs; of these, 454 (79%) were D / R, 84 (14.6%) D /R, 32 (5.6%) D /R, and 5 (0.8%) D / R. Of the 32 D /R patients, 16 were receiving trimethoprimsulfamethoxazole and/or pyrimethamine prophylaxis, and none of those 16 developed toxoplasmosis; however, 4 (25%) of the 16 D /R patients who were not taking either trimethoprimsulfamethoxazole or pyrimethamine developed toxoplasmosis, and all died of the infection. None of the 98 patients who were seropositive for T. gondii preoperatively developed clinical evidence of reactivation of the infection. Infectious episodes, by site of infection. The most common sites of infection for the 1073 IEs included the lung in 301 IEs (28.1%), the oral cavity in 122 (11.4%), the urinary tract in 118 (11%), and the skin in 113 (10.5%; table 2). Most of the pulmonary IEs (301 cases) were caused by bacteria (164 [54.3%]), followed by viruses (53 [17.6%]), fungi (41 [13.6%], excluding PCP), and P. carinii (43 [14.2%]; table 2). Aspergillus species (31 [75.6%]) was responsible for most of the 41 pulmonary IEs caused by fungi (table 4). Thirty (96.8%) of these 31 Aspergillus strains were identified as Aspergillus fumigatus; the remaining one was Aspergillus terreus. A total of 116 (10.8%) of the 1073 IEs involved 12 sites (disseminated); 77 (66.4%) were due to viruses and 30 (25.9%) to fungi (excluding P. carinii; table 2). Of those due to viruses, 63 (81.8%) were caused by CMV (table 5). Of those due to fungi, 17 (56.7%) were caused by Aspergillus (these 17 strains were A. fumigatus; table 4). Each of the 18 infections localized to the mediastinum was caused by bacteria; 9 (50%) were due to gram-positive cocci, almost all of which (88.9%) were Staphylococcus species (71.4% of the staphylococcal strains causing IE in the mediastinum were S. aureus). Most of the IEs involving the liver and biliary tract were due to viral hepatitis (CMV, hepatitis B and C; 32 episodes). Involvement of the gastrointestinal tract (gastritis or colitis) was most likely due to CMV (27 [69.2%]) and Clostridium difficile 632 CID 2001:33 (1 September) Montoya et al.

5 Table 2. Type of organism involved, as related to site of infection, in 1073 infectious episodes in 620 heart transplantation patients at Stanford Medical Center between 16 December 1980 and 30 June No. (%) of episodes Site or type of infection Bacteria Viruses Fungi (not P. carinii) P. carinii Protozoa Total Bloodstream 36 (7.7) (3.4) Bone, joints 6 (1.3) 0 2 (1.8) (0.7) Brain 4 (0.9) 1 (0.2) 1 (0.9) (0.6) Disseminated 5 (1.1) 77 (17.2) 30 (27.5) 0 4 (66.7) 116 (10.8) Gastrointestinal 10 (2.1) 28 (6.3) (16.7) 39 (3.6) Genitalia 0 27 (6) 1 (0.9) 0 1 (16.7) 29 (2.7) Intra-abdominal abscess 27 (5.8) 0 6 (5.5) (3.1) Liver, biliary 2 (0.4) 33 (7.4) 1 (0.9) (3.4) Lung 164 (35) 53 (11.9) 41 (37.6) 43 (100) (28.1) Mediastinum 18 (3.8) (1.7) Meninges 7 (1.5) 0 1 (0.9) (0.7) None determined 2 (0.4) (0.2) Oral cavity 2 (0.4) 108 (24.2) 12 (11) (11.4) Other 29 (6.2) (2.7) Retina 0 5 (1.1) 3 (2.8) (0.7) Skin 1 (0.2) 112 (25.1) (10.5) Subcutaneous 34 (7.3) 0 7 (6.4) (3.8) Tracheobronchial 4 (0.9) 1 (0.2) 2 (1.8) (0.7) Upper respiratory tract a 3 (0.6) (0.3) Urinary tract 114 (24.4) 2 (0.4) 2 (1.8) (11) Total 468 (100) 447 (100) 109 (100) 43 (100) 6 (100) 1073 (100) NOTE. The infectious episodes occurred at a rate of 1.73 episodes per patient. a Includes cases of sinusitis. (9 [23%]). Listeria monocytogenes was the most common organism involving the CNS of our patients, causing 6 (75%) of the cases of meningitis and 3 (60%) of the 5 brain abscesses. Mycobacterium avium complex was responsible for 1 episode of meningitis. Time of occurrence of infections. Data on the median onset (in days) after transplantation (MOT) for the following IEs were available: herpes simplex, 40 days; bacteremia, 48 days; infection with Aspergillus species, 52 days; bacterial pneumonia, 65 days; CMV infection, 71 days; P. carinii infection, 147 days; Nocardia infection, 147 days; candidal infection, 159 days; bacterial urinary tract infection, 209 days; and VZV infection, 299 days (table 6). All cases of CMV infection, bacterial pneumonia, urinary tract infection, and infections caused by Aspergillus species, P. carinii, and Candida species, in relation to the time of occurrence by postoperative month, are shown in figure 1. In figure 1, it appears that the peak of urinary tract infections occurs in the first 2 months after transplantation, whereas in table 6 the median time of onset is 209 days. There is not necessarily a contradiction between the data presented in figure 1 and table 6. The distribution of times is most dense (i.e., has its peak) for small values (!2 months), but the distribution has a long tail, which pulls up the median (and the mean even more; data not shown). Longitudinal trends, impact of prophylactic antimicrobial interventions, and mortality. The longitudinal trends in the annual incidence of some of the most significant IEs and the relationship between incidence and the time in which prophylactic measures were introduced during the study period are depicted in figure 2. Figure 2A illustrates the incidence of IEs due to CMV, HSV, and VZV during the study period and the times at which ganciclovir and iv human CMV immunoglobulin (CMV-IGIV) were introduced as prophylactic measures for our heart transplant recipients. Figure 2B reveals the incidence of IE caused by Aspergillus species and Candida species in relation to the introduction of therapy with ganciclovir, CMV-IGIV, and inhaled amphotericin B. Figure 2C depicts the relationship between the incidence of IEs due to bacteria, Staphylococcus, Nocardia, and Listeria species, and Pneumocystis carinii and the introduction of therapy with ganciclovir, CMV- IGIV, and trimethoprim-sulfamethoxazole. In figures 2B and 2C the incidence of IEs caused by CMV was added to show Infectious Complications of Heart Transplantation CID 2001:33 (1 September) 633

6 Table 3. Site and causes of 468 bacterial infectious episodes in heart transplantation patients at Stanford Medical Center between 16 December 1980 and 30 June Site or type of infection Organism Bloodstream Bone, joints Brain Disseminated GI IAA Liver, biliary Lung Mediastinum Meninges ND OC Other Skin SC TRB UR UT Total Gram-positive Staphylococcus species a Enterococcus species Streptococcus species Listeria monocytogenes Clostridium species Streptococcus pneumoniae 7 7 Gram-negative Escherichia coli Pseudomonas aeruginosa Legionella pneumophila Klebsiella species Enterobacter species Serratia species H. parainfluenzae 7 7 Proteus species Citrobacter species Acinetobacter species Salmonella species Bartonella henselae 1 1 Gram-negative rod, undefined 1 1 Other Nocardia asteroides Mixed anaerobes Mycoplasma pneumoniae Actinomyces israelii Mycobacterium tuberculosis 3 3 Atypical AFB Total NOTE. AFB, acid-fast bacilli; GI, gastrointestinal; IAA, intra-abdominal abscess; ND, none determined; OC, oral cavity; SC, subcutaneous; TRB, tracheobronchial; UR, upper respiratory; UT, urinary tract. a For 51 of the 75 patients, the coagulase status of the Staphylococcus species was known (see text under Infectious episodes, by pathogen ).

7 the temporal relationship between this major opportunistic pathogen and other IEs. The introduction of ganciclovir in January 1987 appeared to have significantly contributed to the already declining incidence of bacterial infections ( P!.0021) and those due to HSV ( P!.020) and Nocardia ( P!.025). Unexpectedly, introduction of inhaled amphotericin B in July 1993 appeared to have positively impacted the incidence of not only IEs due to Aspergillus ( P!.035) but also IEs due to bacteria ( P!.0130), CMV ( P!.014 ), and HSV ( P!.049; figure 2). The longitudinal trends in the annual incidence of death due to infection, rejection, and graft atherosclerosis (survival of the graft) and its temporal relationship with the incidence of CMV infection and the introduction of therapy with ganciclovir, CMV-IGIV, and inhaled amphotericin B are portrayed in figure 3. The attributable mortality estimated for each of the major and most frequent IEs is shown in table 7. DISCUSSION Over the past 20 years, significant progress has been achieved in decreasing the risk of infection in heart transplantation patients [6, 7]. Effectiveness of immunosuppression has been significantly improved, particularly since the introduction of cyclosporine in 1980 [6]; higher survival rates achieved after the introduction of cyclosporine have been directly attributed to decreased mortality associated with infection [2, 17]. Findings in the present study, as well as those of other investigators, reveal that bacterial and viral infections continue to account for 80% 90% of all IEs [18, 19]. In our series, IEs occurred at Figure 1. Occurrence of selected infectious episodes (IEs) by postoperative month (POM) in 620 heart transplantation patients. The abscissa represents the number of IEs, not corrected incidence. Table 4. Site of 109 fungal (non P. Carinii) infectious complications and the causative organisms in heart transplantation patients at Stanford Medical Center between 16 December 1980 and 30 June Site or type of infection Aspergillus Candida Coccidiodes immitis Cryptococcus Zygomycetes a rate of 1.73/patient, were second only to rejection as the cause of early deaths, and were the most common cause of late deaths. Most of the late deaths occurred between 30 days and 1 year after transplantation. In the original series reported from our center in the early 1970s [20], IEs occurred at a rate of 2.83 episodes per patient; this decreased shortly after the introduction of cyclosporine, to 2.1 episodes per patient [17]. A standard protocol for immunosuppression was used for our patients. It is important to emphasize that since the introduction of cyclosporine at our center, major variations in immunosuppressive protocols have not been introduced [21]. Thus, the further decrease in the rate of infection per patient from 2.1 (shortly after introduction Pseudallescheria boydii Blastomyces Yeast, unidentified Hyphae, unidentified Bone, joints Brain 1 1 Disseminated Genitalia 1 1 Intra-abdominal abscess 6 6 Liver, biliary 1 1 Lung Meninges 1 1 Oral cavity Retina Subcutaneous Tracheobronchial 2 2 Urinary tract Total Total Infectious Complications of Heart Transplantation CID 2001:33 (1 September) 635

8 Table 5. Site and causes of 447 viral infectious complications in heart transplantation patients at Stanford Medical Center between 16 December 1980 and 30 June Site or type of infection CMV HSV VZV Hepatitis virus Influenza Avirus Ebstein-Barr virus HIV RSV Parainfluenza virus Bloodstream 0 Brain 1 1 Disseminated Gastrointestinal Genitalia Liver, biliary Lung Oral cavity Retina 5 5 Skin Tracheobronchial 1 1 Urinary tract 2 2 Total NOTE. CMV, cytomegalovirus; HSV, herpes simplex virus; VZV, varicella zoster virus; RSV, respiratory syncytial virus. of cyclosporine) to 1.73 (in the present series) was not related to changes in the immunosuppressive protocols. In addition, significant changes were not introduced involving other factors known to affect immunosuppression, including procedures for donor selection, operative techniques, and underlying diseases and comorbidities in recipients [6]. The further decrease in the incidence of several IEs observed between the series from Stanford Medical Center reported in 1987 by Hofflin et al. [17] and that reported here is likely related to the introduction of different antimicrobial strategies at our institution (see Materials and Methods). The annual incidence of IEs, including those caused by CMV, HSV, VZV, Aspergillus species, bacteria, Nocardia species, Listeria species, and P. carinii steadily declined since Statistically significant declines in the annual incidence of bacterial, HSV, and Nocardia infections were observed after introduction of ganciclovir, and significant declines in those of Aspergillus, bacterial, CMV, and HSV infections were observed following introduction of inhaled amphotericin B. It is likely that the observed decline in incidence of IEs due to CMV also contributed to the decrease in other IEs, a circumstance perhaps related to the observation that infection with CMV enhances immunosuppression in transplantation patients [22, 23]. It is also likely that specific antimicrobial strategies were partially responsible for the shift in the MOT of IEs, including the use of inhaled amphotericin B for Aspergillus and Candida infections and ganciclovir for CMV, HSV, and VZV infections. The period of observation after introduction of CMV immunoglobulin was too short to allow conclusions regarding its impact on the incidence or MOT of IEs. Trimethoprim-sulfamethoxazole is unlikely to have been responsible for the shift in the MOT of IEs such as urinary tract infections, which are Total more likely to be caused by nosocomially acquired gram-negative bacteria resistant to multiple antibiotics. Thus, introduction and routine prophylactic use of antibacterial agents is not likely to have accounted for the shift in MOT of gram-negative bacterial IEs we observed. More likely is that the shift observed with CMV IEs was causally related to the shift in the gramnegative bacterial IEs. Therefore, it is likely that by the shift in the MOT of CMV to a later time, the MOT of other IEs may have been delayed also. Steady declines in the incidence of death due to infection, of rejection, and of graft atherosclerosis were observed over the last 6 years of the study period. Control of IEs, evidenced by the decline in their annual incidence and delay in their MOT, likely contributed significantly to this decrease in mortality. It appears that the decline in incidence of deaths due to infection preceded the decline in the incidence of deaths due to both graft atherosclerosis and rejection. Our data suggest that further improvement in survival of the cohort was related to improved control of the infectious complications. Several investigators have suggested that CMV infection per se worsens the net state of immunosuppression in patients with organ transplants [22 24]. In our patient population, the most common manifestation of CMV disease was the disseminated form, followed by pulmonary and gastrointestinal disease. Involvement of the retina occurred in a small minority of patients. The MOT for CMV disease in our series (71 days) was 4 weeks later than reported by Hofflin et al. [17] in 1987 (44 days). Almost identical changes in the MOT of CMV disease were noted in a trial of ganciclovir to prevent CMV disease in our heart transplantation population (45 days in the placebo group and 72 in the ganciclovir group) [25]. The annual incidence of CMV disease has significantly de- 636 CID 2001:33 (1 September) Montoya et al.

9 clined since It is interesting to note that in the present series the incidence of IEs due to CMV did not decrease significantly after introduction of ganciclovir in 1987; this finding is similar to that in the study at Stanford reported by Merigan et al. [25]. In that study, only a subgroup analysis revealed a significant decline in the incidence of IEs due to CMV among seropositive recipients (but not among seronegative patients), and as discussed above, a clear benefit was observed by the delay in the MOT of CMV infection in each of their subsets of patients. It is interesting to note that in our study the incidence of IEs due to CMV appeared to have significantly declined even further after the decrease in the incidence of aspergillosis (noted after 1 July 1993, when therapy with amphotericin B was instituted or when construction of a hospital parking structure was completed). In addition, the peak for MOT of aspergillosis (23 days in the study by Hofflin et al. [17] and 52 days in the present study) at our center has always preceded the peak for MOT of CMV infection (44 days in the study of Hofflin et al. [17] and 71 days in the present study). These findings raise the possibility that aspergillosis may be an important risk factor for development of CMV disease in heart transplantation patients or that the factors that predispose to development of CMV disease may overlap with those that predispose to aspergillosis but that clinical aspergillosis may be manifested earlier. In our study, most fungal infections were caused by Aspergillus species, more than one-half (57.4%) of which were localized to the lung. Disseminated aspergillosis (with or without CNS disease) was the single IE responsible for the highest mortality rates found in our heart transplantation population. Table 6. Median onset after transplantation (MOT) of selected infectious episodes at Stanford Medical Center. Cause or type of infectious episode MOT, in days (range) [17] a [PR] a Aspergillus species 23 (12 45) 52 (7 885) Bacteremia 21 (ND) 48 (2 3767) Bacterial pneumonia 17 (ND) 65 (1 3138) Candida species 44 (16 64) 159 (1 3155) Cytomegalovirus 44 (16 179) 71 (9 3734) Herpes simplex virus 13 (0 135) 40 (1 3924) Mediastinal and sternal wound 26 (ND) 28 (5 129) Nocardia species ND 147 ( ) Pneumocystis carinii pneumonia ND 147 ( ) Urinary tract infection 98 (ND) 209 (4 3924) Varicella zoster virus 57 (28 270) 299 ( ) NOTE. ND, not determined; PR, present report. a Duration of follow-up for the 2 studies was different. In the study by Hofflin et al. [17], only infectious episodes documented during the first year posttransplantation were included; in the current study, all that occurred by 30 June 1996 were included. Figure 2. Longitudinal trends in the corrected (actuarial) incidence of some of the most significant infectious episodes: A, cytomegalovirus (CMV), herpes simplex virus (HSV), and varicella zoster virus (VZV) infections; B, Aspergillus (Asp.) and Candida (Cand.) infections; C, bacterial (Bact.), Staphylococcus (Staph.), Nocardia (Noc.), Listeria (List.), and P. carinii infections. Arrows and vertical lines show the time at which a prophylactic intervention was routinely introduced: ganciclovir (GCV) in 1987, trimethoprim-sulfamethoxazole (TMP-SMX) in 1988, inhaled amphotericin B (ampho B) in 1993, and iv human CMV immunoglobulin (CMV-IgG) in Infectious Complications of Heart Transplantation CID 2001:33 (1 September) 637

10 Table 7. Mortality attributed to major and most frequent infectious episodes occurring in 620 heart transplantation patients at Stanford Medical Center between 16 December 1980 and 30 June Cause or type of infectious episode Attributable mortality, % Aspergillus species All 60 Pulmonary 40 Disseminated 90 Disseminated plus CNS 100 Cytomegalovirus All 22 Pulmonary 43 Toxoplasmosis 100 Nocardia species 30 Candida species 28 Bacterial pneumonia 21 Pneumocystis carinii pneumonia 19 Herpes simplex virus 22 Varicella zoster virus 15 In an attempt to prevent disease caused by Aspergillus species, administration of inhaled amphotericin B was instituted in July 1993 as a routine prophylactic measure. Using a historical control group, Reichenspurner et al. [26] reported that the actuarial incidence and linearized rate of fungal infections, particularly Aspergillus infections, at Stanford were significantly reduced among patients receiving aerosolized amphotericin B prophylaxis after heart, lung, and heart-lung transplantation [26]. Using a Cox proportional hazards model, we also found that the incidence of aspergillosis significantly declined after 1 July The incidence of aspergillosis did not decline significantly after the introduction on 1 January 1987 of ganciclovir as preemptive therapy; similar findings were reported in the study by Merigan et al. [25]. In that study [25], it was also shown that despite the fact that the incidence of aspergillosis did not change significantly after this intervention, the MOT of aspergillosis was significantly delayed. This observation is also consistent with our findings that the MOT for aspergillosis was 52 days, whereas in the study by Hofflin et al. [17] it was 23 days (table 6). The shift in the MOT for aspergillus infections may have contributed to lower morbidity and/or mortality since the infection would occur in patients with lesser degrees of immunosuppression. Significant construction of a parking structure took place at Stanford Medical Center between 1 December 1991 and 30 September This parking structure was built in front of units where our heart transplantation patients are hospitalized. Because this particular construction was finished at a date so close to the time at which therapy with inhaled amphotericin B was instituted, it is not possible to know how much of the decline can be attributed to which factor. IEs caused by Candida species actually increased during the study period, a finding suggesting that our antifungal prophylactic strategies are not effective in prevention and control of such IEs. The attributable mortality of IEs due to Candida species in the present study (28%) was similar to that reported by other investigators with regard to non solid organ transplantation patients [27]. The high attributable mortality due to IE caused by Candida species warrants the study of other antifungal prophylactic strategies. Pulmonary infections have been recognized as the most common IEs in heart transplantation patients since the earliest reports of infectious complications in these patients [1, 20, 22, 28 30]. In the present series, pulmonary infection accounted for 28% of all IEs; bacteria were the most common cause, and almost half of the bacterial pneumonias occurred in the first 2 months after transplantation. It is unclear why pneumonia develops at a higher incidence in patients with heart transplants than in those with other solid-organ transplants. It has been postulated that perioperative events unique to cardiac patients are risk factors and include pulmonary abnormalities existing before the operation (e.g., congestive heart failure), the effects of surgery itself, and postoperative respiratory care [1, 31]. Each of our 43 IEs caused by P. carinii occurred in patients who did not take or could not tolerate Trimethoprim-sulfa- Figure 3. Longitudinal trends in the corrected incidence of death due to infection (INF.), graft atherosclerosis (GRFT. ATHER.), and rejection (REJ). Also depicted are IEs due to cytomegalovirus (CMV). Arrows and vertical lines show the time at which a prophylactic intervention was routinely introduced: ganciclovir (GCV) in 1987, trimethoprim-sulfamethoxazole (TMP-SMX) in 1988, inhaled amphotericin B (ampho B) in 1993, and intravenous human CMV immunoglobulin (CMV-IgG) in CID 2001:33 (1 September) Montoya et al.

11 methoxazole as a prophylactic agent. Other investigators have reported P. carinii pneumonia (PCP) to occur only in heart transplantation patients who were not receiving trimethoprimsulfamethoxazole [30, 32]. In the present study, PCP occurred as early as day 55 and as late as 7.6 years after transplantation. Thus, for our patients who present with pneumonia and interstitial infiltrates within 2 months after transplantation, P. carinii is an unlikely cause. PCP is also unlikely to occur at any time after transplantation in patients compliant with trimethoprim-sulfamethoxazole prophylaxis. Administration of trimethoprim-sulfamethoxazole for the first year after transplantation as a prophylactic agent against PCP has been recommended for heart transplantation patients [33]. The occurrence of late cases (in our study 23% of the IEs occurred 11 year [ months] after transplantation) over such a widespread period probably does not outweigh the potential hazards associated with chronic administration of trimethoprim-sulfamethoxazole [32, 34]. However, administration of trimethoprim-sulfamethoxazole as prophylaxis for P. carinii infection during the first year following transplantation has not been universally adopted [35]. Waser et al. [36] reported a 4% incidence of PCP among their heart transplant recipients despite the lack of routine use of trimethoprim-sulfamethoxazole. They suggest that this low incidence is related to a low prevalence of P. carinii in the Swiss population and does not justify the routine use of trimethoprim-sulfamethoxazole prophylaxis [36]. At Stanford, the incidence of gram-positive and gram-negative bacterial infections were already declining before prophylactic trimethoprim-sulfamethoxazole was instituted. Thus, it is difficult to attribute this decline to the introduction of trimethoprim-sulfamethoxazole. Gram-negative bacteria were responsible for most of the bacterial IEs, and most were nosocomially acquired; they were most likely to cause an IE within the first month after transplantation. There was a low incidence of disease caused by bacterial pathogens acquired in the community that necessitated hospitalization of the patient. Similarly low rates have been found by other investigators [30]. Despite the fact that pneumococcal and influenza vaccines were not routinely administered to our patients, S. pneumoniae and influenza virus were infrequent causes of IEs in these patients. Other investigators have reported a similarly low frequency of pneumococcal pneumonia in heart transplant recipients vaccinated or not with pneumococcal vaccine [30]. The incidence of Mycobacterium tuberculosis infection in organ transplant recipients worldwide ranges from 0.35% to 15% [37]. Our heart transplantation patients are not routinely tested with PPD for detection of latent M. tuberculosis infection. Only 3 (0.28%) of the 1073 IEs were caused by M. tuberculosis. Future shifts in the demographics of these patients (recipients) toward populations at higher risk for development of tuberculosis or policies of transplantation programs in areas of the world with high rates of endemic tuberculosis may justify the institution of routine PPD testing and, if indicated, prophylaxis for M. tuberculosis. In an early series reported from Stanford, intracranial infection was reported to occur in 14.8% of cardiac transplant recipients [38]. In the current series, only 1.3% of the IEs were reported to involve the CNS; Listeria monocytogenes was responsible for most of these; none of the patients were receiving trimethoprim-sulfamethoxazole prophylaxis. In heart transplant recipients, the risk of toxoplasmosis due to reactivation of the latent infection is low [15, 39 41]. The highest risk of developing disease is in the setting of primary infection, i.e., a seronegative recipient who acquires the parasite from a seropositive donor (D /R ) via the graft [15, 41]. In our study, the higher incidence of previous T. gondii infection observed among recipients (16%) versus that among donors (6%) reflects the increasing seroprevalence of the infection with increasing age. This difference in incidence decreased the likelihood of the number of our patients in the highest risk group (D /R ). Only 5.6% were D /R. None of the D /R patients receiving trimethoprim-sulfamethoxazole and/or pyrimethamine prophylaxis developed toxoplasmosis. In contrast, 25% of the those D /R patients who were not taking either drug developed lethal toxoplasmosis. None of the 98 patients who were seropositive for T. gondii preoperatively developed reactivation that resulted in disease. Our heart transplantation patients routinely receive trimethoprim-sulfamethoxazole for PCP prophylaxis. However, whether a single tablet (double-strength) taken twice daily, 3 times each week, is sufficient to prevent toxoplasmosis in the D /R group is unclear at this time; it seems prudent that for those patients a 6-week course of pyrimethamine be added [14]. The highest mortality attributable to an infectious complication was observed among patients with toxoplasmosis or disseminated aspergillosis. In efforts to reduce mortality due to infection in heart transplantation patients, priority should be given to the prevention and preemptive treatment of these infections. IEs caused by pathogens such as P. carinii, L. monocytogenes, T. gondii, and (most likely) Nocardia asteroides can be prevented with the use of prophylactic agents such as trimethoprim-sulfamethoxazole. IEs due to Aspergillus species are likely to be significantly reduced by the use of inhaled amphotericin B, corrective environmental measures, and the anticipated availability of newer antifungal agents. The introduction of specific antimicrobial strategies for the care of heart transplantation patients at Stanford Medical Center has most likely contributed to the significant decline in the incidence of and mortality due to infectious complications. Infectious Complications of Heart Transplantation CID 2001:33 (1 September) 639

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