The complexity of HLA class II (DRB1, DQB1, DM) associations with disseminated Mycobacterium avium complex infection among HIV-1-seropositive whites

A Rare Case of Disseminated Mycobacterium avium-intracellulare Presenting as Proctitis

Mycobacterium avium intracellulare (MAI) infections are common in Human Immuno-deficiency Virus (HIV) positive patients. MAI infection can have localized or disseminated presentation, patients with low CD4 count presenting with disseminated infection. Fever, abdominal pain, diarrhea, and weight loss are generally the presenting symptoms of disseminated MAI. We present a rare case of a patient with HIV and low CD4 count presenting with proctitis as manifestation of disseminated MAI infection. A 25 year-old-man with HIV came to the emergency room (ER) with complaints of intermittent rectal bleeding for two months. His CD4 count was less than 20 cells/µL. He was MSM (men having sex with men) and has receptive anal intercourse with men. His stool work-up was unrevealing for infectious etiology. Swabs for gonorrhea and chlamydia were negative. Colonoscopy revealed erythematous, congested, friable rectal mucosa with two superficial ulcers. Biopsies of the ulcer were positive for acid fast staining bacteria and the culture grew MAI. His blood culture was negative for growth of acid-fast bacteria (AFB). However, liver biopsy performed for elevated alkaline phosphatase of 958 units/L revealed noncaseating granuloma. Gastro-duodenoscopy with duodenal biopsy did not reveal any mucosal abnormality. He was managed as with disseminated MAI infection using clarithromycin, ethambutol, and rifabutin in addition to HAART therapy. Interval Colonoscopy in 20 months showed resolution of rectal ulcer. The gut is often involved in patients with disseminated MAI infection, with the duodenum being the most common site. MAI infection should be suspected as possible etiology for proctitis in HIV positive patient with low CD4 count, as proctitis, though infrequent can be the sole presentation for disseminated MAI infection in patients with HIV and low CD4 count.

Proctitis Caused by Mycobacterium avium-intracellulare in an HIV-Infected Patient

Infectious proctitis is usually associated with sexually transmitted diseases, especially in HIV-infected individuals. Limited information is found about the role of Mycobacterium avium-intracellulare as a causative agent for this condition. Here, we report the case of an HIV-infected patient with a CD4 count of 304 cells/uL and undetectable HIV viral load, who presented with constipation and painful defecation. Endoscopic evaluation was significant for shallow rectal ulcerations. Histopathology revealed poorly formed granulomas. Stool culture grew Mycobacterium sp. that was further identified as Mycobacterium avium-intracellulare by DNA probe. He was successfully treated with a 3-drug regimen that included azithromycin, ethambutol and rifabutin. We advocate the use of AFB stool culture in cases of proctitis in which initial investigations for sexually transmitted diseases are unrevealing.

HLA antigens and nontuberculous mycobacterial lung disease in Korean patients

BACKGROUND

Human leukocyte antigen (HLA) molecules are known to play an important role in host-defense mechanisms. The aim of this study was to evaluate the association between HLA alleles and lung disease caused by nontuberculous mycobacteria (NTM) in Korean patients.

METHODS

Seventy-eight patients with NTM lung disease (48 patients with Mycobacterium avium-intracellulare complex [MAC] infection and 30 patients with Mycobacterium abscessus infection) were included in the study. HLA-A, -B, and -DRB1 genotyping was performed by polymerase chain reaction using sequence-specific primers. Data from 485 healthy Korean individuals were used as a control.

RESULTS

When compared to controls, patients with NTM lung disease showed an increased frequency of DRB1*11 (OR = 1.91, 95% confidence interval [CI] = 1.01-3.64, p = 0.045, corrected p [pC] > 0.05). In the subgroup analysis, patients with MAC lung disease had an increased frequency of B*46 (OR = 2.23, 95% CI = 1.05-4.73, p = 0.044, pC > 0.05).

CONCLUSIONS

Our data suggest that in a Korean population, patients with NTM lung disease and healthy subjects differ in the frequencies of some HLA alleles. However, when considering corrected p values, our findings are inconclusive.

Immunogenetics of severe respiratory infections: models for the development of new therapeutic strategies

Innate and adaptive immunity plays a critical role in the defence of the lung and other mucosal surfaces exposed to micro-organisms. Anti-microbial peptides and proteins, cytokines and chemokines are important immune weapons as they build up the protective front for the respiratory tract. The notion that susceptibility to infectious diseases may be inherited is widely accepted and, as it is the failure to activate adaptive immunity that may allow infection to become established and progress toward invasion and dissemination, the recognition of specific gene defects affecting the ability of the immune system to overcome invading pathogens may shed light upon those mechanisms of immune regulation that are playing the most critical roles. The aim of the present review is to discuss some of the advances in infection immunogenetics that may lead to identify new strategies in the development of new anti-infectious and anti-inflammatory drugs.