Tuberculosis After Conversion From Azathioprine to Mycophenolate Mofetil in a Long-Term Renal Transplant Recipient

Mycobacterium tuberculosis after solid organ transplantation: A review of more than 2000 cases

BACKGROUND

Mycobacterium tuberculosis (TB) is a common pathogen worldwide, and it may cause significant infection after solid organ transplantation (SOT). We reviewed all reported TB cases to provide an update on its epidemiology, clinical presentation, management, and outcome after SOT.

METHODS

MEDLINE, EMBASE, and OVID were reviewed from January 1, 1998, to December 31, 2016, using keywords tuberculosis and solid organ transplant or transplantation.

RESULTS

There were 187 publications reporting 2082 cases of TB among kidney (n = 1719), liver (n = 253), heart (n = 77), lung (n = 25), and kidney-pancreas (n = 8) recipients. Among cohort studies, the median incidence was 2.37% (range, 0.05%-13.27%) overall. Most TB disease was considered reactivation of latent infection, occurring beyond the first year after SOT. Early-onset cases were seen among donor-derived TB cases. Fever was the most common symptom. Radiologic findings were highly variable. Extrapulmonary and disseminated TB occurred 29.84% and 15.96%, respectively. Multidrug-resistant TB was rare. Treatment using 4 or 5 drugs was commonly associated with hepatotoxicity and graft dysfunction. All-cause mortality was 18.84%.

CONCLUSIONS

This large review highlights the complexity of TB after SOT. Reactivation TB, donor-transmitted infection, extrapulmonary involvement, and disseminated disease are common occurrences. Treatment of TB is commonly associated with hepatotoxicity and graft dysfunction.

Miliary Tuberculosis Presenting With Meningitis in a Patient Treated With Mycophenolate for Lupus Nephritis: Challenges in Diagnosis and Review of the Literature

Tuberculosis is one of the top 10 causes of death worldwide according to the World Health Organization. Central nervous system involvement is usually the least common presentation of tuberculosis occurring in about 1% of all cases but yet can have very devastating outcomes. Lupus nephritis is one of the most common complications of systemic lupus erythematosus with up to two thirds of patients presenting with some degree of renal dysfunction. The mainstay of treatment is glucocorticoids; however, to sustain remission, steroid sparing agents such as cyclophosphamide, azathioprine and mycophenolate mofetil are used. Such patients, in addition to their baseline dysfunctional immune system, have a heightened risk of infections due to these drugs. In this article, we present a young woman who had recently been started on mycophenolate mofetil for control of class V lupus nephritis who presented with headaches, sinus pressure, and fevers. She had a protracted course of hospitalization as she failed to improve clinically and to respond to conventional therapy for acute bacterial sinusitis and meningitis. She was empirically started on antitubercular therapy 9 days after hospitalization. The diagnosis was not confirmed until day 18, the day results of cerebrospinal fluid acid-fast bacillus culture was reported. This case is reported to highlight the challenges in diagnosing Mycobacterium tuberculosis infection in an immunocompromised state and to demonstrate that its presentation can mimic numerous other conditions. Clinicians must maintain a high index of suspicion of Mycobacterium tuberculosis infection in such patients who present with nonspecific or unexplainable symptoms.

SCMBYK: prediction and characterization of bacterial tyrosine-kinases based on propensity scores of dipeptides

Background

Bacterial tyrosine-kinases (BY-kinases), which play an important role in numerous cellular processes, are characterized as a separate class of enzymes and share no structural similarity with their eukaryotic counterparts. However, in silico methods for predicting BY-kinases have not been developed yet. Since these enzymes are involved in key regulatory processes, and are promising targets for anti-bacterial drug design, it is desirable to develop a simple and easily interpretable predictor to gain new insights into bacterial tyrosine phosphorylation. This study proposes a novel SCMBYK method for predicting and characterizing BY-kinases.

Results

A dataset consisting of 797 BY-kinases and 783 non-BY-kinases was established to design the SCMBYK predictor, which achieved training and test accuracies of 97.55 and 96.73%, respectively. Furthermore, the leave-one-phylum-out method was used to predict specific bacterial phyla hosts of target sequences, gaining 97.39% average test accuracy. After analyzing SCMBYK-derived propensity scores, four characteristics of BY-kinases were determined: 1) BY-kinases tend to be composed of α-helices; 2) the amino-acid content of extracellular regions of BY-kinases is expected to be dominated by residues such as Val, Ile, Phe and Tyr; 3) BY-kinases structurally resemble nuclear proteins; 4) different domains play different roles in triggering BY-kinase activity.

Conclusions

The SCMBYK predictor is an effective method for identification of possible BY-kinases. Furthermore, it can be used as a part of a novel drug repurposing method, which recognizes putative BY-kinases and matches them to approved drugs. Among other results, our analysis revealed that azathioprine could suppress the virulence of M. tuberculosis, and thus be considered as a potential antibiotic for tuberculosis treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-016-1371-4) contains supplementary material, which is available to authorized users.

Mycobacterium tuberculosis infection following kidney transplantation

Introduction and Aims. Post-transplant tuberculosis (TB) is a problem in successful long-term outcome of renal transplantation recipients. Our objective was to describe the pattern and risk factors of TB infection and the prognosis in our transplant recipients. Patients and Methods. This study was a retrospective review of the records of 491 renal transplant recipients in our hospital during the period from January 1986 to December 2009. The demographic data, transplant characteristics, clinical manifestations, diagnostic criteria, treatment protocol, and long-term outcome of this cohort of patients were analyzed. Results. 16 patients (3,2%) developed post-transplant TB with a mean age of 32,5 ± 12,7 (range: 13–60) years and a mean post-transplant period of 36,6months (range: 12,3 months–15,9 years). The forms of the diseases were pulmonary in 10/16 (62,6%), disseminated in 3/16 (18,7%), and extrapulmonary in 3/16 (18,7%). Graft dysfunction was observed in 7 cases (43,7%) with tissue-proof acute rejection in 3 cases and loss of the graft in 4 cases. Hepatotoxicity developed in 3 patients (18,7%) during treatment. Recurrences were observed in 4 cases after early stop of treatment. Two patients (12.5%) died. Conclusion. Extra pulmonary and disseminated tuberculosis were observed in third of our patients. More than 9months of treatment may be necessary to prevent recurrence.

Tuberculosis of the genitourinary system-Urinary tract tuberculosis: Renal tuberculosis-Part II

This article reviews the computed tomography and magnetic resonance imaging (MRI) features of renal tuberculosis (TB), including TB in transplant recipients and immunocompromised patients. Multi detector computed tomography (MDCT) forms the mainstay of cross-sectional imaging in renal TB. It can easily identify calcification, renal scars, mass lesions, and urothelial thickening. The combination of uneven caliectasis, with urothelial thickening and lack of pelvic dilatation, can also be demonstrated on MDCT. MRI is a sensitive modality for demonstration of features of renal TB, including tissue edema, asymmetric perinephric fat stranding, and thickening of Gerota's fascia, all of which may be clues to focal pyelonephritis of tuberculous origin. Diffusion-weighted MR imaging with apparent diffusion coefficient (ADC) values may help in differentiating hydronephrosis from pyonephrosis. ADC values also have the potential to serve as a sensitive non-invasive biomarker of renal fibrosis. Immunocompromised patients are at increased risk of renal TB. In transplant patients, renal TB, including tuberculous interstitial nephritis, is an important cause of graft dysfunction. Renal TB in patients with HIV more often shows greater parenchymal affection, with poorly formed granulomas and relatively less frequent findings of caseation and stenosis. Atypical mycobacterial infections are also more common in immunocompromised patients.

Tuberculosis in renal transplant recipients

Infective complications are common after renal transplantation. Tuberculosis (TB) is one of the leading infections following renal transplantation. Reactivation is the most common mode of infection. The factors responsible for this reactivation are chronic liver disease, other coexisting infections, particularly deep mycoses, pneumocystis pneumonia, nocardia, and CMV infections. Cyclosporine use advances the onset of TB to an earlier date. The median onset following transplantation is estimated to be 26 months for those who receive azathioprine and prednisolone as immunosuppression and 11 months for those who receive cyclosporine along with other immunosuppressive agents. Lung is the major site of involvement. Pyrexia of unknown origin is another common presentation. Culture and sensitivity has to be done in all possible cases. Amongst the serological techniques, Interferon alpha production is emerging as the most important. Rifampicin has to be avoided in allograft recipients as it activates cytochrome-P450 enzymes and thereby decreases the therapeutic levels of cyclosporine and prednisolone. The duration of treatment is usually extended for 18 months followed by secondary prophylaxis with isoniazid. Adverse effects of drugs are more often reported in organ recipients and have to be monitored for. Drug resistance is emerging as a problem and appropriate changes in the management have to be carried out.

Report of the First World Transplant Congress

During the past 20 yr, new immunosuppressant medications that reduced the rate of acute rejection became available for transplantation. Long-term survival of transplanted organs, however, did not improve to the extent predicted. Chronic immunosuppression is associated with cardiovascular, metabolic, and renal toxicities that negatively affect patient and graft survival. Therefore, there is a pressing need for new approaches to immunosuppression that might better prevent acute rejection with a safety profile that is superior to current regimens. Moreover, the performance of currently available agents should be largely ameliorated by optimizing drug combinations and dosages. The latter goal can be achieved only through the development of specific immune markers of over- and underimmunosuppression to help tailor the immunosuppressive regimen for individual patients and even to allow safe withdrawal of immunosuppression in selected patients. Recent research has resulted in the discovery of new pathways of alloimmune reactivity, thereby offering novel immunologic targets for more specific and minimally toxic antirejection therapies. Finally, recent achievements pushed transplant medicine forward toward its ultimate goal of achieving a condition of tolerance for allogeneic antigens that prevents acute rejection without maintenance immunosuppression. All of these topics were addressed in the more than 3000 abstracts that were presented at the World Transplant Congress, held in Boston July 22 through 27, 2006.