Infections in Heart, Lung, and Heart-Lung Transplantation

Half a century has passed since the first orthotopic heart transplant took place. Surgical innovations allowed for heart, lung, and heart-lung transplantation to save lives of patients with incurable chronic cardiopulmonary conditions. The complexity of the surgical interventions, chronic host health conditions, and antirejection immunosuppressive medications makes infectious complications common. Infections have remained one of the main barriers for successful transplantation and a source of significant morbidity and mortality. Recognition of infections and its management in this setting require outstanding clinical skills since transplant recipients may not exhibit classic signs or symptoms of disease, and laboratory work has some pitfalls. The prevention, identification, and management of infectious diseases complications in this population are a priority to undertake to improve the medical outcomes of transplantation. Herein, we reviewed the historical aspects, epidemiology, and prophylaxis of infections in heart, lung, and heart-lung transplantation. We also discuss the most prevalent organisms affecting the host and the organ systems involved.

Multiple parasitic infections in a cardiac transplant recipient

Infectious complications represent an important cause of morbidity and death in patients with transplant. Parasitic infections are less frequent than viral and bacterial agents, and are often overlooked. We describe the case of a 13-year-old adolescent, born in São Tomé Island, who was under immunosuppressive therapy after a cardiac transplant. The patient had an intermittent course of diarrhoea, abdominal pain and vomiting. She was admitted dehydrated, and Strongyloides stercoralis, Schistosoma intercalatum and Cystoisospora belli were isolated in her stools. The patient was treated with ivermectin, albendazole, praziquantel and ciprofloxacin with clinical and microbiological resolution. Her immunosuppressive therapy was reduced during hospitalisation. We believe that the parasitic infection was a result of a recrudescence of dormant infections acquired in her homeland. To the best of our knowledge, there are no reports of cystoisosporiasis or schistosomiasis in heart transplant recipients.

Bone marrow suppression and associated consequences in patients after heart transplantation: A 6-year retrospective review

AIMS

To evaluate the incidence of bone marrow suppression and consequences of MMF dose adjustment in patients within the first year after heart transplantation.

METHODS

Group I (n=47) was treated with a regimen currently used in patients after heart transplantation (mycophenolatemofetil - MMF, valganciclovir - VGC and trimethoprim/sulfamethoxazole - TMP-SMX). Group II (n=47) received only MMF of potentially myelotoxic medications. The myelotoxic effect and need for dose modification were assessed. The incidence of rejections and infectious episodes associated with MMF adjustment were analyzed during the first 12 months in Group I.

RESULTS

There was a significantly greater proportion of patients with leukopenia (leukocyte count < 4 x 10^9/L) at 3 months after orthotopic heart transplantation in Group I compared with Group II (19.1% vs 2.1%; P = 0.02). The difference in lymphopenia (lymphocyte count < 0.8 x 10^9/L) at 3 months follow-up was highly significant (38.3 % vs 6.4 %; P = 0.0002). MMF was modified due to bone marrow suppression or severe infection in 63.8% patients in Group I and in only 8.5% of patients in Group II (P < 0.001). Reducing or stopping MMF was not associated with increased rejections. In Group I, at least 1 episode of higher degree cellular or humoral rejection occurred in 35% of patients with the standard MMF dosage compared with only 26% in patients with modified MMF (P = 0.0534).

CONCLUSIONS

Addition of VGC+TMP-SMX to current immunosuppressive medication regimen in patients after heart transplantation is associated with significant lymphocytopenia and leukopenia. Importantly, modification of immunosuppressive prophylaxis (reducing or stopping MMF) leads to normalization of blood count without increased incidence of rejections.

Effects of prednisone on mucociliary clearance in a murine model

All transplant patients are at increased risk of developing pulmonary infections, a significant cause of morbidity and mortality. Immunosuppressants increase the incidence of lung infection by acting not only directly on the inflammatory cells, but also on the native immune system. Experimental studies have shown corticosteroid therapy, which is used in most immunosuppressive protocols after transplantation, to suppress mucus production by inhibiting calceiform. The objective of this study was to evaluate the effects of prednisone on mucociliary clearance. A total of 120 male Wistar rats were distributed into 4 groups. Animals in P1, P2, and P3 groups received daily doses of prednisone (0.625, 1.25, and 2.5 mg/kg/d), and hosts in the Sal group underwent gavage with saline solution (2.5 mL/d). After 7, 15, and 30 days, treatment, animals were killed. We assessed ciliary beating frequency (CBF), mucociliary transport velocity (MCTV), and mucus transportability (MT). There was no significant difference for CBF regarding dose (P = .089) or treatment duration (P = .175). MCTV values of 0.60 ± 0.14 in group P1, 0.59 ± 0.13 in group P2, 0.51 ± 0.19 in group P3, and 0.61 ± 0.08 Group Sal, showed P3 to significantly differ from P1 (P = .048) and Sal (P = .007) groups. Regardless of the prednisone dose, all groups displayed impaired MT compared with the Sal group: P1 (P = .02); P2 (P = .02) P3 (P = .03). There was no interaction between the therapy and the treatment time for CBF (P = .10), MCTV (P = .71), and MT (P = .64). Prednisone reduced the transportability of mucus even when administered at low doses; however, this change was not sufficient to alter the mucociliary clearance. Only high doses of prednisone impaired mucociliary clearance.

Immune monitoring of anti cytomegalovirus antibodies and risk of cytomegalovirus disease in heart transplantation

We sought to determine whether quantitative assessment of anti-cytomegalovirus (CMV) antibodies could be useful to identify patients at risk of cytomegalovirus (CMV) disease after heart transplantation (HT). 75 patients who underwent HT at a single health care center were prospectively studied. Induction therapy included 2 doses of daclizumab and maintenance tacrolimus (n=42) or cyclosporine (n=29), mycophenolate mofetil and prednisone. All patients received prophylaxis with gancyclovir or valganciclovir. Anti-CMV intravenous immunoglobulin (CMV-IG) was added in high risk patients (CMV D+/R- serostatus). Serial determinations of anti-CMV antibodies, immunoglobulins (IgG, IgA, IgM) and IgG-subclasses were analysed. CMV infection was based on detection of the virus by antigenemia. CMV disease consisted of detection of signs or symptoms attributable to this microorganism. Ten patients (13.3%) developed CMV disease. Mean time of development of CMV disease was 3.4+/-1.6 months. In Cox regression analysis, patients with low baseline anti-CMV titers (<4.26 natural logarithm of titer, RH: 8.1, 95%CI: 1.93-34.1, p=0.004) and recipients with 1-month post-HT IgG hypogammaglobulinemia (IgG<500 mg/dl, RH: 4.49, 95%CI: 1.26-15.94, p=0.02) were at higher risk of having CMV disease. Despite use of prophylactic CMV-IG, D+/R- patients showed significantly lower titers of anti-CMV antibodies at 7 d, 30 d and 90 d post HT as compared with HT recipients without infections. Four out of 6 of these patients developed late CMV disease. Monitoring of specific anti-CMV antibodies on the bedside warrants further evaluation as a potential tool to identify heart transplant recipients at higher risk of CMV disease.