Mycobacterium Avium Complex Bacteremia Research Articles

1388. Characteristics of Non-Tuberculous Mycobacterial Infections in Hematopoietic Stem-Cell Transplant Patients

BackgroundHematopoietic stem cell transplantation (HSCT) recipients are at increased risk for non-tuberculous mycobacterial infections (NTMI), but little data exists regarding NTMI in this population. This study aimed to better define the clinical and epidemiological characteristics of NTMI in HSCT patients.MethodsWe performed a retrospective review of patients age ≥ 18 who underwent HSCT between 2000 and 2017 at Yale-New Haven Hospital, and who subsequently had an NTMI based on ATS/IDSA criteria or a culture that grew NTM. We reported patient demographics, illness severity, treatment, and outcomes.ResultsOf 1371 HSCT recipients between 2000 and 2017, 17 (1.2%) had an NTMI or were culture positive. Most patients were male (76.5%), received allogeneic HSCT (70.6%), had graft vs. host disease (GVHD) (70.6%), and received immunosuppression (64.7%). Mycobacterium avium complex (MAC) was isolated in 16 (94.1%). Cultures were mainly positive in respiratory specimens (8 bronchoalveolar lavage, 2 sputum, and 1 lung tissue). Nine of 17 patients (52.9%) were deemed colonized whereas 8 (47.1%) were considered infected. In the infected group, isolated pulmonary infection was the most common presentation (n = 5, 62.5%). Two of the 8 infected patients (25%) had MAC bacteremia. Of those with NTMI, MAC was isolated in 6 (75%), MAC and M. abscessus/chelonae in 1 (12.5%), and M. kansasii in 1 (12.5%). Among those with NTMI, 3 were hypoxic (37.5%) and 4 (50%) had sepsis, though only 1 case of sepsis was directly attributable to NTM. Seven infected patients received antimycobacterial therapy. Four patients (50%) died but none were directly attributed to NTM. Diagnosis was often delayed in these patients, with a median of 44 days (range 14–155 days) from time of initial presentation to diagnosis of NTMI. Median time to death from time of NTMI diagnosis was 75 days (range 16–1825 days).ConclusionNTMI, including disseminated infection, was uncommon in a large cohort of HSCT patients. Careful evaluation of positive cultures in these patients is needed to distinguish infection from colonization. High mortality in HSCT patients may not be directly attributable to NTMI, but the presence of NTM may be a predictor of poor outcomes. Disclosures All authors: No reported disclosures.

1890 An Attack of Disseminated MAC

INTRODUCTION: A 43-year-old woman with a past medical history of AIDS presented with a 3 month history of diarrhea, abdominal pain, and weight loss. She was noted to have pancytopenia with a profound anemia. Alkaline phosphatase was elevated with normal AST and ALT. Stool culture, C diff, shiga toxin, and stool cryptosporidium Ag were negative. Mediastinal, axillary, retroperitoneal, and inguinal lymphadenopathy were noted on CT scan with splenomegaly. CASE DESCRIPTION/METHODS: ID and GI were consulted who recommended initiation of azithromycin, rifabutin, and ethambutol given the high suspicion for disseminated Mycobacterium avium complex (MAC). After 12 days of hospitalization, her diarrhea had not improved, and the decision was made to perform EGD and colonoscopy. EGD demonstrated atrophic mucosa in the 2nd and 3rd portions of duodenum. Colonoscopy showed severe colitis in the ileocecal valve. The TI had multiple erythematous, hypervascular appearing lesions with the appearance of angioectasias. The pathology of the duodenal, terminal ileum, IC valve, and random colon biopsies all showed acid-fast bacilli bacteria within the macrophages. Given the endoscopy findings with blood cultures which were previously positive and eventually grew MAC, the diagnosis of disseminated MAC was confirmed. Her diarrhea gradually improved and she was restarted on HAART before discharge. DISCUSSION: In the post-HAART era, the incidence of diarrhea attributed to opportunistic infections has decreased1; however, the workup and evaluation for infectious diarrhea continues to be paramount. The American Society for Gastrointestinal Endoscopy recommends stool testing for pathogens as the first-line evaluation followed by endoscopy when the diarrheal illness is persistent and stool tests fail to reveal a cause in immunocompromised patients2. MAC can affect several parts of the gastrointestinal system. In one review of previously reported cases of MAC with GI involvement, endoscopy demonstrated involvement of the duodenum (76%), rectum (24%), ileum (6%), colon (4%), esophagus (4%), and jejunum (2%)3. MAC colonization of the gastrointestinal tract is important because it increases the risk of disseminated MAC with the risk of MAC bacteremia approaching 60% with in 1 year4. Our approach to this patient was to perform endoscopy only when her symptoms persisted despite treatment. This case was interesting in that duodenum, ileum, and colon were all affected. Lastly, this case was an excellent example of several classic MAC findings.

Clinical features of patients with bacteraemia caused by Mycobacterium avium complex species and antimicrobial susceptibility of the isolates at a medical centre in Taiwan, 2008–2014

Advanced molecular typing methods have greatly expanded the taxonomy of Mycobacterium avium complex (MAC) species; however, little is known about the epidemiology and clinical features of bacteraemia caused by different MAC species. In this study, the clinical characteristics of patients treated for MAC bacteraemia in a tertiary-care centre in northern Taiwan during 2008–2014 were investigated. Isolates were identified to species level by rpoB gene and 16S–23S rRNA internal transcribed spacer region sequencing. Among 30 patients with bacteraemia due to MAC, the majority (n = 26) had concomitant human immunodeficiency virus (HIV) infection. Of the 30 blood isolates obtained from patients, 24 were M. avium subsp. hominissuis, 4 were Mycobacterium colombiense and 2 were Mycobacterium intracellulare. All four M. colombiense isolates were from HIV-infected patients. Bacteraemia due to M. colombiense was associated with higher 30-day mortality than bacteraemia due to M. avium subsp. hominissuis [2/4 (50%) vs. 1/24 (4%); P = 0.045, Fisher's exact test]. All four M. colombiense isolates were susceptible to clarithromycin, moxifloxacin and linezolid. Among the five patients who received ethambutol treatment and four patients who received fluoroquinolone treatment for various durations between positive MAC cultures, two and three patients, respectively, had isolates with significantly increased (≥4-fold) ethambutol and fluoroquinolone minimum inhibitory concentrations. M. colombiense was the second leading causative pathogen of MAC bacteraemia, comprising 15% of all MAC isolates obtained from HIV-positive patients. Monitoring the susceptibility of MAC isolates to ethambutol and fluoroquinolones is warranted in patients with persistent MAC bacteraemia.

Unusual Presentation for Unusual Infection: Disseminated Mycobacterium Avium-Intracellulare complex (MAC) in Patient with Sickle Cell Anemia Mimicking Blood Transfusion Reaction

Nontuberculous mycobacteria (NTM) are ubiquitous free living soil and water– borne organisms that cause numerous clinical syndromes including lymphadenitis, skin, soft tissue and pulmonary infections, however disseminated infection is almost exclusively in patient with severe immunocompromise (i.e:HIV, Hematological malignancy, and bone marrow transplant).Mycobacterium avium complex (MAC) is hard to diagnose as it is considered slow grower NTM.We describe a case of disseminated Mycobacterium avium-intracellulare complex infection in teenager with sickle hemoglobinopathy with unique presentation mimicking pRBCs transfusion reaction.Patient presented on three different occasions with tachycardia, hypotension and fever within 2-24 hours following pRBCs pheresis, all three episodes were investigated and were negative for transfusion reactions.Patient had central venous catheter (CVC), frequent admissions for vaso-occlusive painful episode, on hydrocortisone for adrenal insufficiency and off Hydroxyurea for two months.Diagnosis of mycobacterium avium complex bacteremia was confirmed by two positive blood cultures, whole body CT scan showed liver nodules, spleen nodules and lung nodules. Pulmonary dissemination was confirmed by Biopsy and culture, Lymphocyte markers showed severe lymphopenia with absolute CD4 count of 64.Patient underwent treatment with three month of four antibiotics followed by 9 months of three antibiotics with removal of the central line, follow up scan showed decrease size and numbers of nodules, patient started tolerating pheresis within one month of the antibiotics initiation.NTM infection should be added to the list of pathogens in sickle cell patients with CVCs and fever and should be considered in frequent pRBC transfusion like reaction with negative workup.Routine blood culture can identify rapid growing NTM but specific mycobacterial blood culture is required in case of other NTM species (slow grower). As dissemination almost always occurs in those with impaired cellular immunity, HIV testing and lymphocyte markers should be performedRemoval of involved CVCs is essential for the treatment as well as appropriate antimicrobial medications. DisclosuresNo relevant conflicts of interest to declare.

Profile of cause of death assigned to adults on antiretroviral therapy in Soweto

This retrospective cohort study describes causes of death in 305 patients (baseline median CD4 count 26/μl) from 2 943 adults on antiretroviral therapy. Acute sepsis (20%), tuberculosis (18%) and Mycobacterium avium complex (MAC) bacteraemia (14%) were the most common causes. Mortality owing to the disease was 66% for MAC bacteraemia and 23% for non-Hodgkin's lymphoma. In 37 patients dying beyond one year on ART, virological failure was present in 11 (30%), and non-HIV-related causes of death occurred in 10. The main causes were acute sepsis (6), tuberculosis (7) and chronic medical conditions (5). Initiating ART at higher CD4 counts should reduce early mortality.

Mycobacterial bacteraemia in patients infected and not infected with human immunodeficiency virus, Taiwan

The clinical characteristics and outcomes of 71 patients with mycobacterial bacteraemia, infected with human immunodeficiency virus (HIV) (n = 47) and not infected with HIV (n = 24) are described. Mycobacterium avium complex (MAC) (54.9%) constituted the most frequently isolated mycobacterium, followed by Mycobacterium tuberculosis (MTB) (38.0%), Mycobacterium kansasii (4.2%), and Mycobacterium abscessus (2.8%). The Beijing family genotype was the most common type in MTB, and Mycobacterium intracellulare was the most common species in MAC. The overall mortality rate was 33.8%; it was lower in HIV-infected than in non-HIV-infected patients. HIV-infected patients were younger, had fewer underlying diseases and better nutritional status, and were more likely to have MAC bacteraemia than MTB bacteraemia.

Nontuberculous Mycobacteria in Solid Organ Transplant Recipients

Nontuberculous Mycobacteria in Solid Organ Transplant Recipients

Prevention of Human Immunodeficiency Virus–Related Opportunistic Infections in France: A Cost‐Effectiveness Analysis

A simulation model of human immunodeficiency virus (HIV) disease, which incorporated French data on the progression of HIV disease in the absence of antiretroviral therapy and on cost, was used to determine the clinical impact and cost-effectiveness of different strategies for the prevention of opportunistic infections in French patients who receive highly active antiretroviral therapy (HAART). Compared with use of no prophylaxis, use of trimethoprim-sulfamethoxazole (TMP-SMZ) increased per-person lifetime costs from euro 185,600 to euro 187,900 and quality-adjusted life expectancy from 112.2 to 113.7 months, for an incremental cost-effectiveness ratio of euro 18,700 per quality-adjusted life-year (euro/QALY) gained. Compared with use of TMP-SMZ alone, use of TMP-SMZ plus azithromycin cost euro 23,900/QALY gained; adding fluconazole cost an additional euro 54,500/QALY gained. All strategies that included oral ganciclovir had cost-effectiveness ratios that exceeded euro 100,000/QALY gained. In the era of HAART, on the basis of French data, prophylaxis against Pneumocystis carinii pneumonia, toxoplasmic encephalitis, and Mycobacterium avium complex bacteremia is cost-effective. Prophylaxis against fungal and cytomegalovirus infections is less cost-effective than are other therapeutic options for HIV disease and should remain of lower priority.

CLINICAL PATHOLOGICAL CONFERENCE

CLINICAL PATHOLOGICAL CONFERENCE

Pulmonary complications in patients with AIDS

HIV infection was first reported in 1981 in USA. It has been 20 years since then. Owing to understandings of pathogenesis of this disease and development of new drugs such as the HIV-specific protease inhibitor (PI), prognosis of disease has been tremendously improved. Especially after 1997 in Japan, the strategy of anti-HIV treatment shifted from two drugs combination to three drugs combination, which is called highly active antiretoviral therapy (HAART). HAART was so effective that prevalence of HIV associated opportunistic infections were decreased dramatically. Mortality among hospitalized HIV-infected patients was decreased from 6.7% in 1996 to 2.6% since then in ACC. However, 80% of patients receiving HAART suffered from side effects and 15% of them had to be changed their treatment due to side effects. Furthermore, an unexpected side effect, namely lipodystrophy syndrome (LDS), was emerged among patients who were receiving HAART more than one year. LDS was first reported as re-distribution of lipid such as central obesity with or without lipo-atrophy from extremities and/or face. Now only cosmetic change, but also it is associated with elevation of lipid and glucose level. Therefore, those patients who have LDS are in face of the risk for the ischemic heart diseases. Our survey indicated that the rate of LDS in Japanese patients were almost same as that of Caucasian patients reported elsewhere. Opportunistic infections associated with HIV infection Treatment for HIV infection consists of two major arms; one is use of anti-HIV drugs to prevent development of AIDS described above and the other is diagnosis, treatment, and prophylaxis of opportunistic infections. There are five very important opportunistic infections; Pneumocystis carinii pneumonia (PCP), cryptococcus meningitis, toxoplasma encephalitis, cytomegalovirus (CMV) infection, and Mycobacterium avium complex (MAC) bacteremia. Because if these five were able to diagnose, a patient can survive under appropriate treatment. On the other hand, if these were not diagnosed, patient must be AIDS death. After introducing HAART, number of CMV retinitis, MAC bacteremia, and AIDS dementia complex were decreasing. However, number of PCP sustained high because PCP is the first indicator disease of AIDS if the patient did not know his HIV status. The first choice of drug is sulfamethoxazole/trimethoprim (ST) for PCP treatment. If the patient were in severe respiratory failure, corticosteroid is used concomitantly. Treatment is usually continued for 3 weeks. We have successfully treated 45 out of 47 cases of PCP for 4 years. However, those patients treated with ST for 3 weeks were limited only 35% because of very high rate of side effects of ST. If the patient was intolerant to ST, treatment was switched to pentamidine. After finishing the treatment, the patient is to be treated with a 5-day course of oral desensitization to ST. More than 80% of patients who were previously intolerant to ST became successfully getting tolerance by this method.

Focal Mycobacterium avium Complex Osteomyelitis in Patients with HIV Infection

Mycobacterium avium complex (MAC) is the most common cause of bacteremia seen in patients with acquired immunodeficiency syndrome (AIDS). Bone and joint infections caused by MAC are exceedingly rare in human immunodeficiency virus (HIV) infected patients. Seven previous cases of focal MAC osteomyelitis have been described in patients with HIV infection. Of these patients, two had focal disease and CD4+ lymphocyte counts >200 cells/mm3. The five other previously described patients had disease associated AIDS and a contiguous focus of infection, either arthritis, sinusitis, or subcutaneous abscess. Three of these patients also had associated MAC bacteremia. We review these previous cases and report a new patient who had isolated MAC osteomyelitis in the setting of AIDS and no evidence of contiguous infection or bacteremia.

Unexpected reactions following highly active anti‐retroviral therapy in patients with HIV‐1 infection and tuberculosis

Purpose:Highly active anti‐retroviral therapy (HAART) dramatically improves the prognosis of AIDS patients. However, some patients with opportunistic infections suffer from the hyperreactive inflammation (HRI) following HAART, which sometimes interferes with the continuation of HAART. In order to clarify the mechanism of HRI, we investigated the clinical course of these cases and performed in vitro and in vivo analyses.Materials and methods:AIDS patients with active opportunistic infections including miliary tuberculosis, Mycobacterium avium complex (MAC) bacteraemia, Pneumocystis carinii pneumonia (PCP), disseminated cryptococcosis were included in the present study. We started HAART after treatment of these opportunistic infections. Blood and clinical samples were obtained from infective sites to make the definitive diagnosis and to prove HRI. Peripheral blood mononuclear cells (PBMC) obtained and stored sequentially during lymphadenitis due to Mycobacterium tuberculosis were stimulated with purified protein derivative (PPD) in vitro and measured lymphocyte proliferation and cytokine production.Results and conclusions:Hyperreactive inflammation occurred 3 weeks on average after starting HAART in most patients who had these opportunistic infections. Discrimination between HRI and deterioration of the infection was sometimes very difficult. If we were able diagnose HRI, we treated the patients with corticosteroid to mitigate HRI. Two‐thirds of the patients continued HAART, but the remaining cases had to have HAART suspended due to severe reactions including fever (> 40°C) and pain of lymphadenitis. In vitro study with the PPD stimulation revealed that proliferating lymphocytes existed in peripheral blood and γ‐interferon was produced from such PBMC. These results might support the fact that the infective site must have the much stronger reaction to the opportunistic pathogen. If it was true, use of steroids makes sense to control the reaction. Actually, treatment with the steroid to HRI is successful. However, how to use the steroid (e.g. how much dose and how long) is to be elucidated from future clinical observations.Acknowledgements:The following doctors are acknowledged for their contribution to this study: M. Tanaka, C. Yasuoka, Y. Takahashi, S. Ida, N. Tachikawa, Y. Kikuchi, A. Yasuoka, and Y. Hirabayashi. This study was supported by a grant for AIDS Research from the Ministry of Health and Welfare of Japan.

Correlation of quantitative bone marrow and blood cultures in AIDS patients with disseminated Mycobacterium avium complex infection.

The relationship between Mycobacterium avium complex (MAC) infection of blood and bone marrow was studied in human immunodeficiency virus-infected patients before and during treatment. Quantitative cultures were obtained at baseline from 17 persons with newly detected MAC bacteremia. Serial blood cultures were obtained, and a second bone marrow sample was obtained at 4 or 8 weeks. At baseline, the median MAC load in bone marrow core samples was 3 log10 higher than in blood. Bone marrow MAC loads ranged widely (866-847,315 cfu/g), and no significant correlation was found between MAC load in blood and that in bone marrow core samples. MAC loads in bilateral bone marrow biopsy samples from 7 subjects were highly correlated. MAC loads declined in blood and bone marrow at similar rates during therapy, but blood was sterilized before bone marrow. Length of survival was inversely associated with initial bone marrow core MAC load but not with blood MAC load. Initiation of treatment when tissue MAC load is low may increase the likelihood of favorable clinical outcome.

Antimicrobial susceptibility of coagulase-negative staphylococci isolated between 1991 and 1996 from a German university hospital

10. Havlir DV, Dube MP, Sattler FR, et al. Prophylaxis against disseminated Mycobacterium avium complex with weekly azithromycin, daily rifabutin or both. N Engl J Med 1996; 335: 392-8. 11. Horsburgh C R , Metchock B, Gordon SM, Havlik JA, McGowan JE, Thompson SE. Predictors of survival in patients with AIDS and disseminated Mycobacterium avium complex disease. J Infect Dis 1994; 170: 573-7. 12. Sathe SS, Gascone F' , Lo W, Pinto R , Reichman LB. Severe anemia is an important negative predictor for survival with disseminated Mycobacterilrm avilrm in acquired immunodeficiency syndrome. Am Rev Respir Dis 1990; 142: 1306-12. 13. Singer J, Thorne A, Phlipps P, et al. Predictors of survival and eradication of Mycobacterium avium complex bacteremia (MAC) in AIDS patients in the Canadian randomized treatment trial. Canadian HIV Trials: Network Protocol 020 Study Group. AIDS

Corneal endothelial deposits in children positive for human immunodeficiency virus receiving rifabutin prophylaxis for mycobacterium avium complex bacteremia

PURPOSE: To assess the potential ocular effects of prophylactic administration of rifabutin in children with symptomatic human immunodeficiency virus (HIV) infection and CD4 counts less than 50 cells per mm3.METHODS: Twenty-five children with HIV infection were enrolled in a phase I-II study of prophylactic administration of systemic rifabutin for prevention of disseminated Mycobacterium avium complex infection and monitored prospectively for the development of ocular complications secondary to HIV infection or drug toxicity.RESULTS: The dose of rifabutin ranged from 5.0 mg to 15.0 mg per kg, and the median ophthalmic follow-up was 24 months. During the study period, six of the children receiving rifabutin prophylaxis for M. avium complex developed unusual bilateral, initially peripheral, stellate, corneal endothelial deposits without associated uveitis. Review of serial corneal drawings and photographs showed an increase in the number of corneal deposits with continued administration of rifabutin. The duration of rifabutin treatment (P = .017) and follow-up (P = .0011) was significantly longer in patients who developed these corneal endothelial changes.CONCLUSION: Corneal endothelial deposits should be considered a potential side effect of rifabutin therapy. To date, these findings have not been sight threatening.

Long-term outcomes of treatment of Mycobacterium avium complex bacteremia using a clarithromycin-containing regimen.

To describe the long-term outcomes of treatment of AIDS-related Mycobacterium avium complex (MAC) bacteremia using a standard clarithromycin-based regimen. Retrospective study of patients with MAC bacteremia diagnosed between April 1992 and April 1995. An urban AIDS clinic One hundred seventy-six consecutive patients with MAC bacteremia. Clarithromycin 500 mg twice daily, ethambutol 800 or 1200 mg daily, and clofazimine 100 mg daily. Late treatment failure (defined as a positive blood culture more than 90 days after starting treatment), clarithromycin susceptibility of initial and treatment-failure isolates, DNA fingerprinting of isolates from treatment failures. Two out of 176 (1.1%) baseline isolates were resistant to clarithromycin. One hundred and fifty-one patients were treated for MAC bacteremia, 144 (95%) with the standard regimen. Of the 117 patients who survived > 90 days after starting therapy, 25 (21%) met the criteria for late treatment failure. Of the 22 treatment-failure isolates available for susceptibility testing, 19 (86%) were resistant to clarithromycin. Therefore, 13% of patients treated using the standard regimen (19 out of 144) had treatment failure associated with the emergence of clarithromycin resistance. Using logistic regression, non-compliance was associated with treatment failure (P = 0.02). Fourteen out of the 17 (82%) evaluable paired isolates had identical DNA fingerprint patterns, whereas three pairs showed that a different strain of MAC was present at the time of treatment failure. Initial resistance to clarithromycin was rare during this period. However, late treatment failure associated with the emergence of clarithromycin resistance was relatively common during long-term follow-up. Most late treatment failures represented emergence of clarithromycin resistance in the initial strain.

Proinflammatory cytokine and human immunodeficiency virus RNA levels during early Mycobacterium avium complex bacteremia in advanced AIDS.

The relationship between Mycobacterium avium complex (MAC) bacteremia and proinflammatory cytokine and human immunodeficiency virus type 1 (HIV-1) RNA levels in AIDS was investigated. During a prospective study, blood samples were drawn monthly for mycobacterial cultures. Sera were available at baseline and onset of MAC bacteremia from 20 cases and at corresponding times from 19 controls. Mean interleukin-6 (IL-6) levels were 154% greater at the time of MAC bacteremia in cases than in controls. The IL-6 levels correlated with body temperature, serum tumor necrosis factor (TNF-alpha) levels, and alkaline phosphatase levels (P < or = .004 for each). Although TNF-alpha levels tended to rise more in MAC patients than in controls, the difference was not significant. However, among both cases and controls, serum TNF-alpha levels rose significantly from baseline to the time of last sample, irrespective of MAC infection (P = .015). Bacteremia was not associated with increased serum HIV-1 RNA levels. Thus, early MAC bacteremia is associated with increases in serum IL-6 levels, while TNF-alpha levels rise over time during advanced AIDS.

Prospective 7-year monitoring of MAC bacteremia in HIV-positive Swedish patients

OBJECTIVE: To record the cumulative incidence of Mycobacterium avium complex (MAC) bacteremia among HIV-infected patients and to study colonization in relation to symptoms of infection. METHODS: In a prospective study, 61 patients with a CD4 count less-than-or-eq, slant200x106/L were followed by cultures from sputum, feces and blood every 3--6 months and for development of MAC bacteremia and clinical symptoms. The main end-points were MAC bacteremia and death. RESULTS: From the start in November 1989 to January 1997 about 34% had developed MAC bacteremia with a median follow-up of 22 months. At the time of positive blood cultures, all but one patient had symptoms consistent with disseminated MAC infection. Positive cultures from respiratory and gastrointestinal tract were recorded before MAC bacteremia in only four patients. All but one had symptoms at the time of positive blood culture. CONCLUSIONS: The incidence of MAC bacteremia was similar to figures in other studies. The presence of symptoms in close relation to positive blood cultures supports late colonization and late infection in HIV disease. Screening patients with samples from the respiratory and gastrointestinal tracts is not useful

Human immunodeficiency virus replication in AIDS patients with Mycobacterium avium complex bacteremia: a case control study. California Collaborative Treatment Group.

The development of opportunistic infections and the administration of vaccines have been associated with transient increases of human immunodeficiency virus (HIV) RNA plasma levels in HIV-infected patients. To determine the relationship between Mycobacterium avium complex (MAC) bacteremia and HIV RNA levels, HIV RNA levels in patients who developed MAC bacteremia (cases) were compared with levels in patients who remained free of MAC disease (controls). Cases and controls were matched for CD4 cell count, prophylaxis against MAC disease, antiretroviral therapy, and duration of follow-up. Mean baseline HIV RNA levels were 4.8 log10 copies/mL in cases and 4.6 log10 copies/mL in controls (P = 0.22). HIV RNA levels increased by a median of 0.4 log in cases but not controls at the time of MAC bacteremia (P = 0.01). In AIDS patients, the onset of MAC bacteremia is associated with a modest but significant increase in serum HIV RNA levels. Increased HIV replication may contribute to the higher mortality associated with MAC bacteremia.

Evaluation of the MycoAKT Latex Agglutination Test for Rapid Diagnosis of Mycobacterium avium Complex Infections

Rapid diagnosis of Mycobacterium avium complex (MAC) bacteremia is important for management of patients with the acquired immunodeficiency syndrome who have disseminated MAC. The purpose of this study was to determine the reliability of the MycoAKT latex agglutination test for direct detection of MAC in positive mycobacterial blood cultures. First, colonies of isolates of previously identified mycobacteria, including 35 MAC, were tested. Of the 55 isolates evaluated, 33 were identified as MAC by the latex test, including 31 of the known MAC and 2 M. chelonae (sensitivity, 88.6%; specificity, 90.0%). Second, broth from 20 ESP II and 20 BACTEC 12B bottles seeded with isolates of MAC were tested. Aliquots from 19 (95%) ESP II cultures and 16 (80%) 12B cultures were positive by the latex test. In phase 3, broth from 115 signal-positive ESP II blood cultures were tested by latex agglutination. Forty-three subcultures from these bottles grew mycobacteria (41 MAC and 2 Mycobacterium tuberculosis complex); the remainder grew no organisms. Broth from 40 of the blood cultures (39 that grew MAC and 1 from which no organisms were recovered) were latex positive; thus, the sensitivity, specificity, and positive and negative predictive values of the latex test for direct identification of MAC in ESP II blood cultures were 95.1, 98.6, 97.5, and 97.3%, respectively. The mean time to detection of MAC was 14.6 days (range, 6–34 days) with the direct latex test, compared with 18.3 days (range, 9–36 days) with subculture and probe (p < 0.05).