Latent Mycobacterium Avium Infection Causing a Mycotic Suprarenal Aortic Aneurysm in a Human Immunodeficiency Virus–Positive Patient

Aortic Graft Infection With Mycobacterium Avium Complex

Aortic graft infections are uncommon complications after endovascular aortic surgery. In the majority of cases, gram-positive and then gram-negative organisms are the causative agents leading to this condition. Atypical organisms are traditionally not responsible for graft infection unless the patient is immunocompromised. We are reporting a case of culture-confirmed mycobacterium avium complex infection of an aortic graft in a well-controlled patient with HIV who had an undetected viral load and a CD4 count of 324 while on highly active antiretroviral therapy.

Total resection of an infected aortic arch aneurysm caused by Mycobacterium avium: a case report

Background

Infected aortic arch aneurysms caused by Mycobacterium avium are rare in immunocompetent individuals. Promptly recognizing these aneurysms is important because delays in treatment result in aneurysm rupture and a high fatality rate. Although Salmonella species, Streptococcus species, Staphylococcus aureus, and S. epidermis are commonly found in immunocompetent individuals, to our knowledge, infected aortic arch aneurysms caused by M. avium have not yet been reported.

Case presentation

We report the case of a 63-year old immunocompetent man who underwent total arch replacement following infection by the nontuberculous mycobacteria M. avium. The procedure involved total aneurysmal resection and arch replacement with a rifampicin-bonded gelatin-sealed woven Dacron graft. He was discharged without complications and remained asymptomatic after 30 months.

Conclusion

In this brief report, we outline and discuss the rare successful case of total arch replacement using total aneurysmal resection and rifampicin-bonded gelatin-sealed woven Dacron graft for an infected aortic arch aneurysm resulting from M. avium in an immunocompetent patient.

Many Different Patterns under a Common Flag: Aortic Pathology in HIV-A Review of Case Reports in Literature

BACKGROUND

Availability of highly active antiretroviral therapy (HAART) for HIV has prolonged life expectancy of patients but has also increased the incidence of non-AIDS comorbid conditions. Among these, there are cardiovascular diseases, and aortic involvement has been described in patients with HIV in the form of aortitis, aneurysms, or dissections. Our study aims to describe aortic pathology occurring in patients with HIV, focusing on clinical and surgical presentation, management, and outcome, through a review of cases published in literature.

METHODS

MEDLINE (www.ncbi.nlm.nih.gov/pubmed) database was reviewed for "aortitis" OR "aortic aneurysm" OR "aortic dissection" AND HIV. Research was restricted to English language. Only case reports were included. Data on patients' age, sex, traditional risk factors, timing from HIV diagnosis, pharmacological details, coinfection (syphilis, hepatitis C virus [HCV], and hepatitis B virus [HBV]), anatomical localization of lesion, presence of inflammatory involvement, rapid growing or rupture, and surgical treatment and outcomes were collected and summarized in tables.

RESULTS

Forty articles (51 cases) were included in the study. The mean age of patients was 48.8 ± 8.3 years. Male sex was preponderant (43 cases, 84.3%). Among traditional risk factors, hypertension and smoking were the most frequently reported ones (14 and 13 cases, respectively), followed by vasculopathy involving other arterial districts, dyslipidemia, diabetes, and drug addiction. In 3 cases, HIV was diagnosed in the same time as aortic pathology, whereas in most cases, aortic event occurred after five years from HIV diagnosis. In 30.5% of cases for which data on pharmacologic management were available, no treatment or poor adherence was reported. Coinfection occurred in some cases (syphilis in 6, HCV in 5, and HBV in 3). As for anatomical involvement, isolated thoracic lesions were more frequent (24, 47.1%), followed by abdominal and thoracoabdominal lesions. The etiology ranged from bacterial mycotic aneurysms to tertiary syphilis, postsurgical complications, or atherosclerosis. In 3 cases, HIV vasculitis was directly suggested, and in another 2, no other potential etiology had been diagnosed through cultural tests. Open surgical treatment was carried out in 30 cases (58.8%), and in addition, 10 endovascular (19.6%) and 2 hybrid procedures were described. Inflammatory features occurred in 7 cases, and a rapid evolution of lesions in 6. In 9 cases (17.6%), rupture occurred. Mortality was reported in 8 cases (15.7%).

CONCLUSIONS

Aortic pathology may occur in patients with HIV. The entanglement of different patterns of pathological involvement of the aortic wall, secondary to immune dysregulation, infectious process, or atherosclerotic damage that may co-occur in one single case, results in a very challenging management of the condition. Because of the increased life expectancy of patients and immigration from regions with both high HIV and coinfection prevalence, the incidence of aortic pathology could increase in the upcoming years, suggesting the urgent need for further studies to optimize management in these very complex cases.

Novel Screen to Assess Bactericidal Activity of Compounds Against Non-replicating Mycobacterium abscessus

Mycobacterium abscessus infections are increasing worldwide. Current drug regimens are largely ineffective, yet the current development pipeline for M. abscessus is alarmingly sparse. Traditional discovery efforts for M. abscessus assess the capability of a new drug to inhibit bacterial growth under nutrient-rich growth conditions, but this does not predict the impact when used in the clinic. The disconnect between in vitro and in vivo activity is likely due to the genetic and physiological adaptation of the bacteria to the environmental conditions encountered during infection; these include low oxygen tension and nutrient starvation. We sought to fill a gap in the drug discovery pipeline by establishing an assay to identify novel compounds with bactericidal activity against M. abscessus under non-replicating conditions. We developed and validated a novel screen using nutrient starvation to generate a non-replicating state. We used alamarBlue^® to measure metabolic activity and demonstrated this correlates with bacterial viability under these conditions. We optimized key parameters and demonstrated reproducibility. Using this assay, we determined that niclosamide was bactericidal against non-replicating bacilli, highlighting its potential to be included in M. abscessus regimens. In contrast, most other drugs currently used in the clinic for M. abscessus infections, were completely inactive, potentially explaining their poor efficacy. Thus, our assay allows for rapid identification of bactericidal compounds in a model using conditions that are more relevant in vivo. This screen can be used in a high-throughput way to identify novel agents with properties that promise an increase in efficacy, while also shortening treatment times.

Aortic Endograft Infection with Mycobacterium chimaera and Granulicatella adiacens, Switzerland, 2014

We describe an aortic endograft infection caused by Mycobacterium chimaera and Granulicatella adiacens, successfully treated with prolonged antimicrobial drug therapy after complete explantation of the infected endoprosthesis and extra-anatomical reconstruction. Whole-genome sequencing analysis did not indicate a close relationship to bacterial strains known to cause infections after cardiac surgery.