Mesenteritis in immunosuppressed patient with Mycobacterium genavense infection

Mycobacteriosis is a major complication in immunosuppressed patients as a result of HIV infection, with nontuberculous Mycobacterium spp. frequently being involved, such as Mycobacterium genavense (M. genavense) [1]. M. genavense is a slow growing Mycobacterium, ubiquitous, reportedly isolated from pets, tap water and the gastrointestinal tract of humans [2–5]. M. genavense, which was first described in the 1990s, associated with AIDS, is nowadays recognized as an opportunistic pathogen because of other immunodeficiency causes (solid-organ or hematopoietic stem cell transplantation or immunosuppressive therapy) [1,3,6]. A prevalence of 3.9--13% M. genavense infection between mycobacterial disseminated infections in HIV-positive patients was found, and cases were described in Europe, North America and Australia [1,3,5]. Most of the HIV-positive patients infected with M. genavense have advanced HIV disease with low CD4+ T-lymphocyte count (less than 148 cells/μl) and mycobacterial disseminated infection [1,3,4]. Fever, malaise and weight loss are some of the most common signs and symptoms, also associated with gastrointestinal symptoms (abdominal pain, diarrhoea and vomiting). There is a predominance of abdominal symptoms associated with M. genavense when compared with other mycobacteria [3,7]. The median survival rate of an AIDS patient with M. genavense disseminated infection was about 6 months, with a better median survival (10--12 months) more recently, probably related to a greater awareness of mycobacterial diseases, better diagnostic methods and improvement of HAART [1,3]. Sclerosing mesenteritis is a rare idiopathic disease characterized by inflammation and fibrosis usually of the small intestine mesentery or root of the mesentery [8–10]. The pathogenic mechanisms beyond it seem to be related to abdominal surgery or trauma, autoimmune diseases, paraneoplastic syndromes and infections [8,9]. Due to the low frequency of sclerosing mesenteritis, there are no guidelines on the management or treatment of this entity [8,9]. A small number of cases of mesenteric involvement because of M. genavense have been described in the literature [7,11,12]. A 39-year-old caucasian man was diagnosed with HIV type 1 [CD4+ T-lymphocyte count 13 cells/μl (0.9%) and HIV viral load of 259 692 copies/ml], and visceral Kaposi's sarcoma in 2015 and started tenofovir/emtricitabine with ritonavir-boosted darunavir. In 2016, he presented fever and weight loss; laboratory findings revealed persistent anaemia, elevated liver enzymes, CD4+ T-lymphocyte count was 40/μl and HIV viral load was undetectable (less than 50 copies/ml). On physical examination, he had an enlarged liver, which was confirmed with abdominal computed tomography, also revealing enlarged lymph nodes of the mesenteric root (Fig. 1). The identification of M. genavense in a bone narrow sample and a liver biopsy presenting granulomas and acid-fast bacillus supported the diagnosis of M. genavense-disseminated infection, so that the patient started clarithromycin, ethambutol and rifabutin. Eighteen months after antimycobacterial treatment, the patient was admitted to the hospital with 3 months of diarrhoea, dyspnea and weight loss; on physical examination, he presented peripheral oedema of the lower limbs and diminished respiratory sounds at the right hemi-thorax. Analytically, HIV viral load was 123 copies/ml, CD4+ T-lymphocyte count was 219/μl (12%) and serum protein level was low showing severe hypoalbuminemia (12 g/l), which, after exclusion of kidney disease, we concluded to be secondary to protein-losing enteropathy. Other infections were excluded. Imaging scans revealed right pleural effusion (a transudative effusion at laboratory testing), deep venous thrombosis of the left subclavian vein, moderate ascites, oedema of the intestinal walls, and densification of the entire mesenteric root surrounding mesenteric vessels and occluding the superior mesenteric vein, suggesting sclerosing mesenteritis (Fig. 1). The patient underwent laparotomy that showed an extensive retractile tumor involvement of the mesentery. Histology findings were proliferation of fusiform and inflammatory lymphoid cells confirming an inflammatory mesenteric process and favouring myofibroblastic inflammatory tumor or sclerosing mesenteritis on immunohistochemistry. Prednisolone and tamoxifen were initiated, but clinical deterioration led to death 45 days after hospital admission.Fig. 1: Abdominal computed tomography scan revealing enlarged lymph nodes on the mesenteric root at the time of Mycobacterium genavense disseminated infection diagnosis (a) and the evolution to densification of the entire mesenteric root surrounding mesenteric vessels suggesting sclerosing mesenteritis, as a long-term complication of the infection (b).Although life expectancy has increased since the beginning of the HAART era in HIV-positive patients, opportunistic infections still have a significant burden in morbidity and mortality. A rare and irreversible complication of a M. genavense-disseminated infection in a patient with a good clinical, laboratory and imaging response to combined antiretroviral and antimycobacterial therapy during 15 months, evolving to a chronic fibrotic and reactive process causing great morbidity is described. We highlight the difficulty on reaching a definitive diagnosis and the lack of information on managing and treating mesenterial inflammatory involvement by mycobacteriosis, suggesting that designed studies with this complication in consideration would be useful. Acknowledgements A.C., R.G. and J.C. contributed to the conception, design, drafting and critical revision of the article. O.C. and T.M. were involved in clinical decision-making, supervised patient treatment and contributed to the critical revision of the article. F.M. was involved in clinical decision-making, supervised patient treatment, contributed to the critical revision of the article and approved the final version of the draft for publication. Conflicts of interest There are no conflicts of interest.