Disseminated tuberculosis in human immunodeficiency virus infection: ineffective immunity, polyclonal disease and high mortality

The Value of 18F-FDG PET/CT in the Diagnosis of Tuberculous Pleurisy and in the Differential Diagnosis between Tuberculous Pleurisy and Pleural Metastasis from Lung Adenocarcinoma

Objectives

This study aims to investigate the diagnostic value of 18F-FDG PET/CT in tuberculous pleurisy (TBP) and the differential diagnostic value of 18F-FDG PET/CT between TBP and pleural metastasis from lung adenocarcinoma (PMLAC).

Materials and Methods

The features of pleura on PET and hybrid CT were retrospectively studied in 20 patients with TBP and 32 patients with PMLAC. The ROC curve was used to evaluate the diagnostic effectiveness of these indices for TBP and PMLAC, and binary logistic regression analysis was conducted to identify independent predictors of TBP and PMLAC.

Results

There were significant differences in pleural 18F-FDG uptake pattern on PET (P=0.001), pleural morphology pattern on CT (P=0.002), the maximum diameter of the pleural nodule (P=0.001), and interlobular fissure nodule (P=0.001) between TBP and PMLAC groups. The diffused pleural FDG uptake type on PET (odds ratio (OR) = 6.0, 95% CI 2.216–16.248, P=0.001) and the lamellar pleural thickening type on CT (OR = 4.4, 95% CI 2.536–7.635, P=0.001) were independent predictors of TBP, with 60% and 55% sensitivity, 96.6% and 90.6% specificity, and 82.7% and 77.0% accuracy. The combined diagnostic sensitivity, specificity, and accuracy for TBP were 70%, 87.5%, and 80.8%. The mixed pleural FDG uptake type on PET (OR = 5.106, 95% CI 2.024–12.879, P=0.001), the mixed pleural thickening type on CT (OR = 2.289, 95% CI 1.442–3.634, P=0.001), and the maximum diameter of the pleural nodule (OR = 1.027, 95% CI 1.012–1.042, P=0.001) were independent predictors of PMLAC, with 78.1%, 71.9%, and 87.5% sensitivity, 85%, 80%, and 85% specificity, and 80.8%, 75%, and 86.5% accuracy. The combined diagnostic sensitivity, specificity, and accuracy for PMLAC were 96.9%, 85%, and 90.4%.

Conclusions

18F-FDG PET/CT is of great clinical value in the diagnosis of TBP and in the differential diagnosis between TBP and PMLAC.

Tuberculosis incidence in country of origin is a key determinant of the risk of active tuberculosis in people living with HIV: Data from a 30-year observational cohort study

INTRODUCTION

People living with HIV (PLWH) are at high risk of active tuberculosis (TB) but this risk in the era of antiretroviral treatment (ART) remains unclear. It is critical to identify the groups who should be prioritised for latent TB (LTBI) screening. In this study we identified the risk factors associated with developing incident TB disease, by analysing a 30-year observational cohort.

METHODS

We evaluated PLWH in Leicester, UK, between 1983 and 2017 to ascertain those who developed active TB and the timing of this in relation to HIV diagnosis; whether before, concurrently with, or more than 3 months after the diagnosis of HIV (incident TB). Predictors of incident TB were ascertained using Cox proportional hazards models.

RESULTS

In all, 325 out of 2158 (15.1%) PLWH under care had had active TB; 64/325 (19.7%) prior to HIV diagnosis, 161/325 (49.5%) concurrently with/within 3 months of HIV diagnosis and 100/325 (30.8%) had incident TB. Incident TB risk was 4.57/1000 person-years. Increased TB incidence in the country of birth was associated with an increased risk of developing incident TB [50-149/100 000 population, adjusted hazard ratio (AHR) = 3.10, 95% CI: 0.94-10.20; 150-249/100 000 population, AHR = 7.14, 95% CI: 3.46-14.74; 250-349/100 000 population, AHR = 5.90, 95% CI: 2.32-14.99; ≥ 350/100 000 population, AHR = 3.96, 95% CI: 1.39-11.26].

CONCLUSIONS

Tuberculosis risk remains high among PLWH and is related to TB incidence in the country of birth. Further work is required to determine whether specific groups of PLWH should be targeted for programmatic LTBI screening, and whether it will result in high uptake and completion of chemoprophylaxis and is cost-effective for widespread implementation.

Prevalence and evaluation of risk factors of anti-retroviral therapy failure among human immunodeficiency virus/acquired immune deficiency syndrome patients in North India

BACKGROUND

The prevalence of anti-retroviral therapy (ART) failure is not uniform in India. In this study we attempted to determine the prevalence and risk factors of treatment failure among patients who were on ART for >1 y.

METHODS

We conducted an ambispective study from 2017 to 2019 in the All India Institute of Medical Sciences, New Delhi, India. Patients and their past medical records were examined to determine clinical, immunological and virological failure.

RESULTS

Among 301 enrolled patients, the majority was male (61.8%), with a mean age of 36.98±10.84 y. The prevalence of ART failure in our study was 10.63% (32/301). Clinical, immunological and virological failure rates were 1.66%, 10.63% and 5.65%, respectively. The maximum chance of failure was the tenofovir-lamivudine-nevirapine (33.3%) regimen followed by the stavudine-lamivudine-nevirapine (30.4%) regimen. Among the nucleoside reverse transcriptase inhibitors, a stavudine-based regimen had a significantly greater chance of failure (25.8%) compared with tenofovir (9.6%) and zidovudine (7.9%) regimens (p<0.005). Low baseline CD4 count and development of tuberculosis after ART initiation were significantly (p<0.05) associated with treatment failure in univariate analysis. Patients with a low peak CD4 count (adjusted odds ratio [AOR 4.26 {95% confidence interval <CI> 1.83 to 9.88}]) and who developed symptoms after ART initiation (AOR 3.77 [95% CI 1.47 to 9.69]) had significantly higher odds of treatment failure in the multivariate analysis (p<0.001).

CONCLUSIONS

Early identification of risk factors by regular follow-up and selection of the proper ART regimen can reduce the rate of treatment failure.

Methods for Detecting Mycobacterial Mixed Strain Infections-A Systematic Review

Mixed strain infection (MSI) refers to the concurrent infection of a susceptible host with multiple strains of a single pathogenic species. Known to occur in humans and animals, MSIs deserve special consideration when studying transmission dynamics, evolution, and treatment of mycobacterial diseases, notably tuberculosis in humans and paratuberculosis (or Johne's disease) in ruminants. Therefore, a systematic review was conducted to examine how MSIs are defined in the literature, how widespread the phenomenon is across the host species spectrum, and to document common methods used to detect such infections. Our search strategy identified 121 articles reporting MSIs in both humans and animals, the majority (78.5%) of which involved members of the Mycobacterium tuberculosis complex, while only a few (21.5%) examined non-tuberculous mycobacteria (NTM). In addition, MSIs exist across various host species, but most reports focused on humans due to the extensive amount of work done on tuberculosis. We reviewed the strain typing methods that allowed for MSI detection and found a few that were commonly employed but were associated with specific challenges. Our review notes the need for standardization, as some highly discriminatory methods are not adapted to distinguish between microevolution of one strain and concurrent infection with multiple strains. Further research is also warranted to examine the prevalence of NTM MSIs in both humans and animals. In addition, it is envisioned that the accurate identification and a better understanding of the distribution of MSIs in the future will lead to important information on the epidemiology and pathophysiology of mycobacterial diseases.

Tuberculosis: a focused review for the emergency medicine clinician

INTRODUCTION

Tuberculosis (TB) is a common disease worldwide, affecting nearly one-third of the world's population. While TB has decreased in frequency in the United States, it remains an important infection to diagnose and treat.

OBJECTIVE

This narrative review discusses the evaluation and management of tuberculosis, with an emphasis on those factors most relevant for the emergency clinician.

DISCUSSION

TB is caused by Mycobacterium tuberculosis and is highly communicable through aerosolized particles. A minority of patients will develop symptomatic, primary disease. Most patients will overcome the initial infection or develop a latent infection, which can reactivate. Immunocompromised states increase the risk of primary and reactivation TB. Symptoms include fever, prolonged cough, weight loss, and hemoptysis. Initial diagnosis often includes a chest X-ray, followed by serial sputum cultures. If the patient has a normal immune system and a normal X-ray, active TB can be excluded. Newer tests, including nucleic acid amplification testing, can rapidly diagnose active TB with high sensitivity. Treatment for primary and reactivation TB differs from latent TB. Extrapulmonary forms can occur in a significant proportion of patients and involve a range of different organ systems. Patients with human immunodeficiency virus are high-risk and require specific considerations.

CONCLUSIONS

TB is a disease associated with significant morbidity and mortality. The emergency clinician must consider TB in the appropriate setting, based on history and examination. Accurate diagnosis and rapid therapy can improve patient outcomes and reduce the spread of this communicable disease.

Urogenital tuberculosis - epidemiology, pathogenesis and clinical features

Tuberculosis (TB) is the most common cause of death from infectious disease worldwide. A substantial proportion of patients presenting with extrapulmonary TB have urogenital TB (UG-TB), which can easily be overlooked owing to non-specific symptoms, chronic and cryptic protean clinical manifestations, and lack of clinician awareness of the possibility of TB. Delay in diagnosis results in disease progression, irreversible tissue and organ damage and chronic renal failure. UG-TB can manifest with acute or chronic inflammation of the urinary or genital tract, abdominal pain, abdominal mass, obstructive uropathy, infertility, menstrual irregularities and abnormal renal function tests. Advanced UG-TB can cause renal scarring, distortion of renal calyces and pelvic, ureteric strictures, stenosis, urinary outflow tract obstruction, hydroureter, hydronephrosis, renal failure and reduced bladder capacity. The specific diagnosis of UG-TB is achieved by culturing Mycobacterium tuberculosis from an appropriate clinical sample or by DNA identification. Imaging can aid in localizing site, extent and effect of the disease, obtaining tissue samples for diagnosis, planning medical or surgical management, and monitoring response to treatment. Drug-sensitive TB requires 6-9 months of WHO-recommended standard treatment regimens. Drug-resistant TB requires 12-24 months of therapy with toxic drugs with close monitoring. Surgical intervention as an adjunct to medical drug treatment is required in certain circumstances. Current challenges in UG-TB management include making an early diagnosis, raising clinical awareness, developing rapid and sensitive TB diagnostics tests, and improving treatment outcomes.

Identification of a Novel Serum Biomarker for Tuberculosis Infection in Chinese HIV Patients by iTRAQ-Based Quantitative Proteomics

Tuberculosis (TB) is a major comorbidity in HIV patients as well as a serious co-epidemic. Traditional detection methods are not effective or sensitive for the detection of Mycobacterium tuberculosis at the early stage. TB has become a major cause of lethal on HIV patients. We employed isobaric tags for relative and absolute quantitation (iTRAQ) technology to identify the different host responses in HIV-noTB and HIV-TB patients’ sera. Given the diversity of HIV subtypes, which results in a variety of host responses in different human populations, we focused on the Chinese patients. Of the 25 proteins identified, 7 were increased and 18 were decreased in HIV-TB co-infected patients. These proteins were found to be involved in host immune response processes. We identified a candidate protein, endoglin (ENG), which showed an 4.9 times increase by iTRAQ and 11.5 times increase by ELISA. ENG demonstrated the diagnostic efficacy and presented a novel molecular biomarker for TB in HIV-infected Chinese patients. This study provides new insight into the challenges in the diagnosis and effective management of patients with HIV-TB.

Whole genome sequencing reveals mycobacterial microevolution among concurrent isolates from sputum and blood in HIV infected TB patients

Background

In the context of advanced immunosuppression, M. tuberculosis is known to cause detectable mycobacteremia. However, little is known about the intra-patient mycobacterial microevolution and the direction of seeding between the sputum and blood compartments.

Methods

From a diagnostic study of HIV-infected TB patients, 51 pairs of concurrent blood and sputum M. tuberculosis isolates from the same patient were available. In a previous analysis, we identified a subset with genotypic concordance, based on spoligotyping and 24 locus MIRU-VNTR. These paired isolates with identical genotypes were analyzed by whole genome sequencing and phylogenetic analysis.

Results

Of the 25 concordant pairs (49 % of the 51 paired isolates), 15 (60 %) remained viable for extraction of high quality DNA for whole genome sequencing. Two patient pairs were excluded due to poor quality sequence reads. The median CD4 cell count was 32 (IQR; 16–101)/mm³ and ten (77 %) patients were on ART. No drug resistance mutations were identified in any of the sequences analyzed. Three (23.1 %) of 13 patients had SNPs separating paired isolates from blood and sputum compartments, indicating evidence of microevolution.

Using a phylogenetic approach to identify the ancestral compartment, in two (15 %) patients the blood isolate was ancestral to the sputum isolate, in one (8 %) it was the opposite, and ten (77 %) of the pairs were identical.

Conclusions

Among HIV-infected patients with poor cellular immunity, infection with multiple strains of M. tuberculosis was found in half of the patients. In those patients with identical strains, whole genome sequencing indicated that M. tuberculosis intra-patient microevolution does occur in a few patients, yet did not reveal a consistent direction of spread between sputum and blood. This suggests that these compartments are highly connected and potentially seed each other repeatedly.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1737-2) contains supplementary material, which is available to authorized users.

Inverting the pyramid: increasing awareness of mycobacterial sepsis in sub-Saharan Africa

Disseminated Mycobacterium tuberculosis is a leading cause of bloodstream infection and severe sepsis in sub-Saharan African settings with a high burden of tuberculosis (TB) and human immunodeficiency virus (HIV) infection. Despite the high prevalence of M. tuberculosis bacteremia in these settings it is under-recognized. This is in part because timely diagnosis of M. tuberculosis bacteremia is difficult using traditional TB diagnostics. Novel triage algorithms and rapid diagnostic tests are needed to expedite the identification and treatment of patients with severe sepsis due to M. tuberculosis bacteremia. In this article, we emphasize the importance of M. tuberculosis bacteremia as an under-recognized etiology of severe sepsis, and discuss the potential role of two emerging rapid diagnostic tests in the triage and prognostication of critically ill patients with advanced HIV infection and suspected disseminated M. tuberculosis. We conclude with the recommendation that clinicians in high TB-HIV burden settings strongly consider empiric anti-tuberculosis treatment in patients with advanced HIV infection and severe sepsis in the appropriate clinical context. Future studies are needed to assess diagnostic and prognostic algorithms for severe sepsis caused by disseminated M. tuberculosis in these settings, and the safety, efficacy, and duration of empiric anti-tuberculosis treatment.

PET/CT imaging of Mycobacterium tuberculosis infection

Tuberculosis has a high morbidity and mortality worldwide. Mycobacterium tuberculosis (Mtb) has a complex pathophysiology; it is an aerobic bacillus capable of surviving in anaerobic conditions in a latent state for a very long time before reactivation to active disease. In the latent tuberculosis infection, the individual has no clinical evidence of active disease, but exhibits a hypersensitive response to proteins of Mtb. Only some 5–10 % of latently infected individuals appear to have reactivation of tuberculosis at any one time point after infection, and neither imaging nor immune tests have been shown to predict tuberculosis reactivation reliably. The complex pathology of the organism provides multiple molecular targets for imaging the infection and targeting therapy. Positron emission tomography (PET) integrated with computer tomography (CT) provides a unique opportunity to noninvasively image the whole body for diagnosing, staging and assessing therapy response in many infectious and inflammatory diseases. PET/CT is a powerful noninvasive tool that can rapidly provide three-dimensional views of disease deep within the body and conduct longitudinal assessment over time in one particular patient. Some PET tracers, such as ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG), have been found to be useful in various infectious diseases for detection, assessing disease activity, staging and monitoring response to therapy. This tracer has also been used for imaging tuberculosis. ¹⁸F-FDG PET relies on the glucose uptake of inflammatory cells as a result of the respiratory burst that occurs with infection. Other PET tracers have also been used to image different aspects of the pathology or microbiology of Mtb. The synthesis of the complex cell membrane of the bacilli for example can be imaged with ¹¹C-choline or ¹⁸F-fluoroethylcholine PET/CT while the uptake of amino acids during cell growth can be imaged by 3′-deoxy-3′-[¹⁸F]fluoro-l-thymidine. PET/CT provides a noninvasive and sensitive method of assessing histopathological information on different aspects of tuberculosis and is already playing a role in the management of tuberculosis. As our understanding of the pathophysiology of tuberculosis increases, the role of PET/CT in the management of this disease would become more important. In this review, we highlight the various tracers that have been used in tuberculosis and explain the underlying mechanisms for their use.

Paradoxical reactions and immune reconstitution inflammatory syndrome in tuberculosis

The coalescence of the HIV-1 and tuberculosis (TB) epidemics in Sub-Saharan Africa has had a significant and negative impact on global health. The availability of effective antimicrobial treatment for both HIV-1 (in the form of highly active antiretroviral therapy (HAART)) and TB (with antimycobacterial agents) has the potential to mitigate the associated morbidity and mortality. However, the use of both HAART and antimycobacterial therapy is associated with the development of inflammatory paradoxical syndromes after commencement of therapy. These include paradoxical reactions (PR) and immune reconstitution inflammatory syndromes (IRIS), conditions that complicate mycobacterial disease in HIV seronegative and seropositive individuals. Here, we discuss case definitions for PR and IRIS, and explore how advances in identifying the risk factors and immunopathogenesis of these conditions informs our understanding of their shared underlying pathogenesis. We propose that both PR and IRIS are characterized by the triggering of exaggerated inflammation in a setting of immunocompromise and antigen loading, via the reversal of immunosuppression by HAART and/or antimycobacterials. Further understanding of the molecular basis of this pathogenesis may pave the way for effective immunotherapies for the treatment of PR and IRIS.

Point-of-Care Ultrasound Assessment of Tropical Infectious Diseases--A Review of Applications and Perspectives

The development of good quality and affordable ultrasound machines has led to the establishment and implementation of numerous point-of-care ultrasound (POCUS) protocols in various medical disciplines. POCUS for major infectious diseases endemic in tropical regions has received less attention, despite its likely even more pronounced benefit for populations with limited access to imaging infrastructure. Focused assessment with sonography for HIV-associated TB (FASH) and echinococcosis (FASE) are the only two POCUS protocols for tropical infectious diseases, which have been formally investigated and which have been implemented in routine patient care today. This review collates the available evidence for FASH and FASE, and discusses sonographic experiences reported for urinary and intestinal schistosomiasis, lymphatic filariasis, viral hemorrhagic fevers, amebic liver abscess, and visceral leishmaniasis. Potential POCUS protocols are suggested and technical as well as training aspects in the context of resource-limited settings are reviewed. Using the focused approach for tropical infectious diseases will make ultrasound diagnosis available to patients who would otherwise have very limited or no access to medical imaging.

High Genotypic Discordance of Concurrent Mycobacterium tuberculosis Isolates from Sputum and Blood of HIV-Infected Individuals

Background

Among HIV-infected individuals with CD4 less than 200 cells/mm³, tuberculosis often has an atypical presentation, is more likely to be disseminated and is diagnostically challenging. We sought to understand the genotypic discordance of concurrent sputum and blood M. tuberculosis (MTB) isolates from HIV-infected individuals.

Methods

From a prospective diagnostic accuracy study with 182 HIV-infected culture-positive TB adults, isolates were obtained from 51 of 66 participants who were MTB culture-positive by both sputum and blood. Isolates were subjected to susceptibility testing to 1^st line drugs, spoligotyping and 24 locus- MIRU-VNTR.

Results

The median age of the participants was 31 (IQR; 27–38) years and 51% were male. The median CD4 count was 29 (IQR; 10–84) cells/mm³ with 20% taking ART; 8.0% were previously treated for TB, and 63% were AFB smear-negative. The isolates belonged to two of the main global MTB-lineages; East-African-Indian (L3) 17 (16.7%) and Euro-American (L4) 85 (83.3%). We identified 26 (51.0%) participants with discordant MTB-genotypes between sputum and blood, including two patients with evidence of mixed infection in either compartment. Having discordant MTB-genotypes was not predicted by the MTB-lineage in either blood or sputum, CD4 cell count, or any other clinical characteristic.

Conclusions

There is a high genotypic discordance among M. tuberculosis concurrently isolated from sputum and blood of HIV-infected individuals. These findings suggest that infection with more than one strain of M. tuberculosis occurs in at least half of patients with advanced HIV infection.

Relationship Between Blood Concentrations of Hepcidin and Anemia Severity, Mycobacterial Burden, and Mortality Among Patients With HIV-Associated Tuberculosis

Background

Anemia is very common in patients with human immunodeficiency virus (HIV)–associated tuberculosis, and hepcidin may be key in mediating this. We explored the relationship between blood hepcidin concentrations and anemia severity, mycobacterial burden and mortality in patients with HIV-associated tuberculosis.

Methods

Consecutive unselected HIV-infected adults in South Africa were systematically investigated for tuberculosis. Three groups were studied: 116 hospitalized inpatients with HIV infection and tuberculosis (hereafter, “hospitalized patients”), 58 ambulatory outpatients with HIV infection and newly diagnosed tuberculosis (hereafter, “ambulatory patients with tuberculosis”), and 58 ambulatory outpatients with HIV infection and without tuberculosis (hereafter, “ambulatory patients without tuberculosis”). Blood hepcidin concentrations were determined for all patients. Vital status at 3 months was determined, and independent predictors of mortality were identified.

Results

Median hepcidin concentrations were 38.8 ng/mL among hospitalized patients, 19.1 ng/mL among ambulatory patients with tuberculosis, and 5.9 ng/mL among ambulatory patients without tuberculosis (P < .001). In both groups with HIV-associated tuberculosis, hepcidin concentrations were strongly associated with greater anemia severity. Additionally, strong, graded associations were observed between hepcidin and composite indices of mycobacterial burden and dissemination. Patients dying within 3 months had significantly higher hepcidin concentrations, which independently predicted mortality.

Conclusions

High hepcidin concentrations were strongly associated with disseminated disease, anemia, and poor prognosis in patients with HIV-associated tuberculosis. Hepcidin may be a mechanistically important mediator underlying the high prevalence of severe anemia in these patients.

Characterization of the Burkholderia mallei tonB Mutant and Its Potential as a Backbone Strain for Vaccine Development

Background

In this study, a Burkholderia mallei tonB mutant (TMM001) deficient in iron acquisition was constructed, characterized, and evaluated for its protective properties in acute inhalational infection models of murine glanders and melioidosis.

Methodology/Principal Findings

Compared to the wild-type, TMM001 exhibits slower growth kinetics, siderophore hyper-secretion and the inability to utilize heme-containing proteins as iron sources. A series of animal challenge studies showed an inverse correlation between the percentage of survival in BALB/c mice and iron-dependent TMM001 growth. Upon evaluation of TMM001 as a potential protective strain against infection, we found 100% survival following B. mallei CSM001 challenge of mice previously receiving 1.5 x 10⁴ CFU of TMM001. At 21 days post-immunization, TMM001-treated animals showed significantly higher levels of B. mallei-specific IgG1, IgG2a and IgM when compared to PBS-treated controls. At 48 h post-challenge, PBS-treated controls exhibited higher levels of serum inflammatory cytokines and more severe pathological damage to target organs compared to animals receiving TMM001. In a cross-protection study of acute inhalational melioidosis with B. pseudomallei, TMM001-treated mice were significantly protected. While wild type was cleared in all B. mallei challenge studies, mice failed to clear TMM001.

Conclusions/Significance

Although further work is needed to prevent chronic infection by TMM001 while maintaining immunogenicity, our attenuated strain demonstrates great potential as a backbone strain for future vaccine development against both glanders and melioidosis.

Burkholderia mallei and B. pseudomallei are the causative agents of glanders and melioidosis, respectively. In addition to the recent rise in cases of glanders and the endemicity of melioidosis worldwide, these pathogens have gained attention as potential bioweapons. Further, these pathogens have huge potential for aerosol delivery and often produce fatal infection amongst untreated individuals. Both pathogens are difficult to treat, and even with antibiotic intervention, patients relapse or get re-infected. A big challenge for vaccine development against these pathogens includes identification of broadly protective antigens and a better understanding of the correlates of protection from both acute and chronic infections. Our study is the first to demonstrate significant protection against a lethal challenge with both Burkholderia species. Because TMM001 persists in immunized mice, we propose that this attenuated organism is a promising backbone-based strain from which a legitimate vaccine candidate can be generated.

Chronic infections of the small intestine

PURPOSE OF REVIEW

Chronic infections of the small intestine cause significant morbidity and mortality globally. This review focuses on the recent advances in the field of our understanding of selected intestinal infections.

RECENT FINDINGS

Primary and secondary immunodeficiency increase the susceptibility to many chronic intestinal infections. Endoscopy and intestinal biopsies are central to establishing a diagnosis of these conditions. Tuberculosis (TB) remains a major global health challenge. Emerging therapeutic agents to counteract multidrug-resistant strains have shown clinical efficacy, but concerns regarding mortality remain. PCR-based diagnostic TB tests have the potential to reduce diagnostic delays, but remain to be validated for intestinal infections. Adjunctive diagnostic imaging modalities can differentiate infections from Crohn's disease with increasing accuracy. Whipple's disease remains rare, but there have been substantial advances in our understanding of the causative organism Tropheryma whipplei. Extended treatment with broad-spectrum antibiotics is effective in most cases. The narrow therapeutic window and limited armamentarium for treating invasive filamentous fungal infections contribute to their significant morbidity and high rates of mortality.

SUMMARY

The speed and accuracy of diagnosing chronic intestinal infections have improved with recent imaging and laboratory methodologies. Significant research opportunities remain for clinicians and scientists to improve the diagnostic accuracy and clinical outcomes of chronic intestinal infections.

Autoantibodies binding to ubiquitin-fold modifier-conjugating enzyme 1 (Ufc1) and pleckstrin homology domain containing, family G (with RhoGef domain) member 2 (Plekhg2) are associated with mycobacterial infections

OBJECTIVES

The diagnosis of extrapulmonary tuberculous infections and nontuberculous mycobacterial (NTM) infections is difficult because the symptoms are nonspecific and suitable specimens for bacterial culture are often not available. Recent publications reported the existence of autoantibodies in tuberculous infections. We screened for specific autoantibodies in mycobacterial infections.

METHODS

We screened four in 29 patients with active mycobacterial infections and different controls using protein array technology. We could identify autoantibodies against ubiquitin-fold modifier-conjugating enzyme 1 (Ufc1) and pleckstrin homology domain containing, family G (with RhoGef domain) member 2 (Plekhg2) in all four patients. Subsequently, we designed enzyme-linked immunosorbent assays (ELISAs) for the detection of autoantibodies binding to Ufc1 and Plekhg2.

RESULTS

Autoantibodies binding to Ufc1 and Plekhg2 were found in 19 of 29 patients (66%) with active mycobacterial infections. In comparison, we found these autoantibodies in one of 31 patients (3%) with successfully treated mycobacterial infections, in three of 40 (8%) HIV-infected patients not receiving combination antiretorviral therapy (cART) and in six of 134 (5%) blood donors. Interestingly, six of eight (75%) patients with HIV-associated B-cell non-Hodgkin lymphoma (B-NHL) at the onset of disease had autoantibodies against Ufc1 and Plekhg2, but none of nine (0%) patients after treatment of HIV-associated B-NHL, none of seven patients with non-HIV-associated B-NHL and 11 of 115 (10%) patients with other malignant diseases had autoantibodies against both proteins.

CONCLUSIONS

In view of the high frequency of these autoantibodies, we postulate that they might be of potential use for additional diagnostics for mycobacterial infections, and further studies may shed light on the pathomechanisms of these two autoantibodies.

Molecular epidemiology of HIV-associated tuberculosis in Dar es Salaam, Tanzania: strain predominance, clustering, and polyclonal disease

Molecular typing of Mycobacterium tuberculosis can be used to elucidate the epidemiology of tuberculosis, including the rates of clustering, the frequency of polyclonal disease, and the distribution of genotypic families. We performed IS6110 typing and spoligotyping on M. tuberculosis strains isolated from HIV-infected subjects at baseline or during follow-up in the DarDar Trial in Tanzania and on selected community isolates. Clustering occurred in 203 (74%) of 275 subjects: 124 (80%) of 155 HIV-infected subjects with baseline isolates, 56 (69%) of 81 HIV-infected subjects with endpoint isolates, and 23 (59%) of 39 community controls. Overall, 113 (41%) subjects had an isolate representing the East Indian "GD" family. The rate of clustering was similar among vaccine and placebo recipients and among subjects with or without cellular immune responses to mycobacterial antigens. Polyclonal disease was detected in 6 (43%) of 14 patients with multiple specimens typed. Most cases of HIV-associated tuberculosis among subjects from this study in Dar es Salaam resulted from recently acquired infection. Polyclonal infection was detected and isolates representing the East Indian GD strain family were the most common.

Bacteremic disseminated tuberculosis in sub-saharan Africa: a prospective cohort study

BACKGROUND

Disseminated tuberculosis is a major health problem in countries where generalized human immunodeficiency virus (HIV) infection epidemics coincide with high tuberculosis incidence rates; data are limited on patient outcomes beyond the inpatient period.

METHODS

We enrolled consecutive eligible febrile inpatients in Moshi, Tanzania, from 10 March 2006 through 28 August 2010; those with Mycobacterium tuberculosis bacteremia were followed up monthly for 12 months. Survival, predictors of bacteremic disseminated tuberculosis, and predictors of death were assessed. Antiretroviral therapy (ART) and tuberculosis treatment were provided.

RESULTS

A total of 508 participants were enrolled; 29 (5.7%) had M. tuberculosis isolated by blood culture. The median age of all study participants was 37.4 years (range, 13.6-104.8 years). Cough lasting >1 month (odds ratio [OR], 13.5; P< .001), fever lasting >1 month (OR, 7.8; P = .001), weight loss of >10% (OR, 10.0; P = .001), lymphadenopathy (OR 6.8; P = .002), HIV infection (OR, undefined; P < .001), and lower CD4 cell count and total lymphocyte count were associated with bacteremic disseminated tuberculosis. Fifty percent of participants with M. tuberculosis bacteremia died within 36 days of enrollment. Lower CD4 cell count (OR, 0.88; P = .049) and lower total lymphocyte count (OR, 0.76; P = .050) were associated with death. Magnitude of mycobacteremia tended to be higher among those with lower CD4 cell counts, but did not predict death.

CONCLUSIONS

In the era of free ART and access to tuberculosis treatment, almost one half of patients with M. tuberculosis bacteremia may die within a month of hospitalization. Simple clinical assessments can help to identify those with the condition. Advanced immunosuppression predicts death. Efforts should focus on early diagnosis and treatment of HIV infection, tuberculosis, and disseminated disease.

The non-human primate model of tuberculosis

Non-human primates (NHPs) are used to model human disease owing to their remarkably similar genomes, physiology, and immune systems. Recently, there has been an increased interest in modeling tuberculosis (TB) in NHPs. Macaques are susceptible to infection with different strains of Mycobacterium tuberculosis (Mtb), producing the full spectrum of disease conditions, including latent infection, chronic progressive infection, and acute TB, depending on the route and dose of infection. Clearly, NHPs are an excellent model of human TB. While the initial aim of the NHP model was to allow preclinical testing of candidate vaccines and drugs, it is now also being used to study pathogenesis and immune correlates of protection. Recent advances in this field are discussed in this review. Key questions such as the effect of hypoxia on the biology of Mtb and the basis of reactivation of latent TB can now be investigated through the use of this model.

Effectiveness of an integrated real-time PCR method for detection of the Mycobacterium tuberculosis complex in smear-negative extrapulmonary samples in an area of low tuberculosis prevalence

Early extrapulmonary tuberculosis (EPTB) diagnosis is particularly difficult. Among 108 smear-negative extrapulmonary samples showing a positive culture for Mycobacterium tuberculosis complex (43 body fluids and 65 nonliquid specimens), 63 (58.3%) were positive with the Xpert MTB/RIF assay (GX). GX sensitivity was quite low for samples from sterile locations (especially for pleural fluids: 26.9%) but high for some nonliquid samples, like abscess aspirates (76.5%). In summary, GX may be a useful tool to be considered for EPTB diagnosis.

Predictors of Virologic Failure in HIV/AIDS Patients Treated with Highly Active Antiretroviral Therapy in Brasília, Brazil During 2002-2008

Little data exists concerning the efficacy of the antiretroviral therapy in the Federal District in Brazil, therefore in order to improve HIV/AIDS patients’ therapy and to pinpoint hot spots in the treatment, this research work was conducted. Of 139 HIV/AIDS patients submitted to the highly active antiretroviral therapy, 12.2% failed virologically. The significant associated factors related to unresponsiveness to the lentiviral treatment were: patients’ place of origin (OR = 3.28; IC95% = 1.0–9.73; P = 0.032) and Mycobacterium tuberculosis infection (RR = 2.90; IC95% = 1.19–7.02; P = 0.019). In the logistic regression analysis, the remaining variables in the model were: patients’ birthplace (OR = 3.28; IC95% = 1.10–9.73; P = 0.032) and tuberculosis comorbidity (OR = 3.82; IC95% = 1.19–12.22; P = 0.024). The patients enrolled in this survey had an 88.0% therapeutic success rate for the maximum period of one year of treatment, predicting that T CD4⁺ low values and elevated viral loads at pretreatment should be particularly considered in tuberculosis coinfection, besides the availability of new antiretroviral drugs displaying optimal activity both in viral suppression and immunological reconstitution.