Chest radiographic findings in patients with tuberculosis with recent or remote infection

Active pulmonary tuberculosis: something old, something new, something borrowed, something blue

Tuberculosis remains a major global health issue affecting all countries and age groups. Radiology plays a crucial role in the diagnosis and management of pulmonary tuberculosis (PTB). This review aims to improve understanding and diagnostic value of imaging in PTB. We present the old, well-established findings ranging from primary TB to the common appearances of post-primary TB, including dissemination with tree-in-bud nodularity, haematogenous dissemination with miliary nodules and lymphatic dissemination. We discuss new concepts in active PTB with special focus on imaging findings in immunocompromised individuals. We illustrate PTB appearances borrowed from other diseases in which the signs were initially described: the reversed halo sign, the galaxy sign and the cluster sign. There are several radiological signs that have been shown to correlate with positive or negative sputum smears, and radiologists should be aware of these signs as they play an important role in guiding the need for isolation and empirical anti-tuberculous therapy.

Clinical and radiologic characteristics of radiologically missed miliary tuberculosis

While chest CT provides important clue for diagnosis of miliary tuberculosis (TB), patients are occasionally missed on initial CT, which might delay the diagnosis. This study was to evaluate the clinical and radiological characteristics of radiologically missed miliary TB.Total 117 adult patients with microbiologically confirmed miliary TB in an intermediate TB-burden country were included. 'Missed miliary TB' were defined as the case in which miliary TB was not mentioned as a differential diagnosis in the initial CT reading. Clinical characteristics and radiologic findings including the predominant nodule size, demarcation of miliary nodules and disease extent on CT were retrospectively evaluated. Findings were compared between the missed and non-missed miliary TB groups. Multivariable analyses were performed to determine independent risk factors of missed miliary TB.Of 117 patients with miliary TB, 13 (11.1%) were classified as missed miliary TB; these patients were significantly older than those with non-missed miliary TB (median age, 71 vs 57 years, P = .024). There was a significant diagnostic delay in the missed miliary TB group (P < .001). On chest CT, patients with missed miliary TB had a higher prevalence of ill-defined nodules (84.6% vs 14.4%; P < .001), miliary nodule less than 2 mm showing granular appearance (69.2% vs 12.5%; P < .001), and subtle disease extent (less than 25% of whole lung field, 46.2% vs 8.7%; P < .001). Multivariable analysis revealed that only CT findings including ill-defined nodule (Odd ratios [OR], 15.64; P = .002) and miliary nodule less than 2 mm (OR, 10.08; P = .007) were independently associated with missed miliary TB.Approximately 10% of miliary TB could be missed on initial chest CT, resulting in a delayed diagnosis and treatment. Caution is required in patients with less typical CT findings showing ill-defined miliary nodules less than 2 mm showing granular appearance and follow-up CT might have a benefit.

Impact of emphysema on sputum culture conversion in male patients with pulmonary tuberculosis: a retrospective analysis

Background

Although cigarette smoking may have a negative impact on the clinical outcome of pulmonary tuberculosis (PTB), few studies have investigated the impact of smoking-associated lung diseases. Emphysema is a major pathological finding of smoking-related lung damage. We aimed to clarify the effect of emphysema on sputum culture conversion rate for Mycobacterium tuberculosis (MTB).

Methods

We retrospectively studied 79 male patients with PTB confirmed by acid-fast bacillus smear and culture at Jikei University Daisan Hospital between January 2015 and December 2018. We investigated the sputum culture conversion rates for MTB after starting standard anti-TB treatment in patients with or without emphysema. Emphysema was defined as Goddard score ≥ 1 based on low attenuation area < − 950 Hounsfield Unit (HU) using computed tomography (CT). We also evaluated the effect on PTB-related CT findings prior to anti-TB treatment.

Results

Mycobacterial median time to culture conversion (TCC) in 38 PTB patients with emphysema was 52.0 days [interquartile range (IQR) 29.0–66.0 days], which was significantly delayed compared with that in 41 patients without emphysema (28.0 days, IQR 14.0–42.0 days) (p < 0.001, log-rank test). Multivariate Cox proportional hazards analysis showed that the following were associated with delayed TCC: emphysema [hazard ratio (HR): 2.43; 95% confidence interval (CI): 1.18–4.97; p = 0.015), cavities (HR: 2.15; 95% CI: 1.83–3.89; p = 0.012) and baseline time to TB detection within 2 weeks (HR: 2.95; 95% CI: 1.64–5.31; p < 0.0001). Cavities and consolidation were more often identified by CT in PTB patients with than without emphysema (71.05% vs 43.90%; p = 0.015, and 84.21% vs 60.98%; p = 0.021, respectively).

Conclusions

This study suggests that emphysema poses an increased risk of delayed TCC in PTB. Emphysema detection by CT might be a useful method for prediction of the duration of PTB treatment required for sputum negative conversion.

Delayed Isolation of Active Pulmonary Tuberculosis in Hospitalized Patients: A Pivotal Role of Radiologic Evaluation

OBJECTIVE. The purpose of this study was to determine factors related to delayed isolation of patients hospitalized with active pulmonary tuberculosis (TB). MATERIALS AND METHODS. A total of 130 immunocompetent hospitalized patients with active pulmonary TB who had positive sputum culture results from January 2015 to December 2017 were reviewed. Delayed isolation of pulmonary TB was defined as failure to initiate airborne isolation within the first 3 days of hospitalization. Clinical and microbiologic characteristics of the patients and radiologic features on chest radiography (n = 130) and chest CT (n = 118) were retrospectively reviewed. Findings were compared between patients with early isolation and those with delayed isolation. Univariate and multivariate analyses were performed to determine independent predictors of delayed isolation. RESULTS. Forty-four patients (34%) had delayed isolation after initial hospitalization. On univariate and multivariate analyses, atypical presentation of active pulmonary TB on CT (odds ratio, 7.203; 95% CI, 2.203-23.551; p = 0.001) and concurrent lung parenchymal diseases on CT (odds ratio, 14.605; 95% CI, 3.274-65.155; p < 0.001) were significant predictors of delayed isolation of patients with active pulmonary TB. CONCLUSION. Awareness of the factors related to delayed diagnosis of active pulmonary TB is important to avoid an unexpected in-hospital outbreak of TB and control the disease. Atypical presentation of active pulmonary TB and concurrent lung parenchymal diseases on CT are significant factors related to delayed isolation of hospitalized patients with active pulmonary TB.

18F-FDG Positron-Emission Tomography/Computed Tomography Findings of Radiographic Lesions Suggesting Old Healed Pulmonary Tuberculosis and High-risk Signs of Predicting Recurrence: A Retrospective Study

Pulmonary tuberculosis (PTB) is a common worldwide infection with high mortality and morbidity, especially in developing countries. This study analyzed PET/CT findings in tumor patients with radiographic lesions suggesting old healed pulmonary tuberculosis (OHPTB) and imaging follow-up to find and verify PET/CT signs that may predict tuberculosis recurrence. A retrospective analysis of the tumor patients was carried out. These patients underwent 18F-FDG PET/CT in our center from 2010 to 2018. Confirmation of tuberculosis recurrence was obtained by follow-up of morphological changes in old lesions by PET/CT or CT. In total, 238 patients with a complete medical history were included in the final study, and 22 patients experienced OHPTB recurrence. We found that the SUVmax of tuberculosis in PET/CT was significantly increased in the recurrence group compared to the non-recurrence group [5.00 (3.40, 7.30) vs. 1.10 (0.80, 1.30), P < 0.001]. The ROC curve showed good discrimination, with an AUC of 0.980, and a cut-off SUVmax value of 2.15 was identified (the sensitivity was 90.5%, the specificity was 97.2%, the positive predictive value was 76.0%, and the negative predictive value was 99.1%). Both the tumor and the anti-tumor treatment can cause the patient to be immunocompromised and might further cause the recurrence of OHPTB. Positive imaging on 18F-FDG PET can predict the recurrence of OHPPT. Although there might be a false positive, 18F-FDG PET can greatly narrow the monitoring range. A negative result on imaging has high reliability for eliminating the possibility of tuberculosis recurrence. PET/CT has important clinical significance in tuberculosis management in patients with concurrent OHPTB.

Serum Exosomal miRNAs Are Associated with Active Pulmonary Tuberculosis

Introduction

Tuberculosis (TB) remains a major threat to human health. Due to the limited accuracy of the current TB diagnostic tests, it is critical to determine novel biomarkers for this disease. Circulating exosomes have been used as diagnostic biomarkers in various diseases.

Objective of the Study

In this pilot study, we examined the expression of miRNAs as biomarker candidates for the diagnosis of TB infection.

Methods

Serum-derived exosomes were isolated from TB patients and matched control subjects. The expression of miR-484, miR-425, and miR-96 was examined by RT-PCR methods.

Results

The expression of miR-484, miR-425, and miR-96 were significantly increased in serum of TB patients which correlated with the TB infection level. A receiver operating characteristic (ROC) curve analysis showed the diagnostic potency of each individual serum exosomal miRNA with an area under the curve (AUC) = 0.72 for miR-484 (p < 0.05), 0.66 for miR-425 (p < 0.05), and 0.62 for miR-96 (p < 0.05).

Conclusion

These results demonstrate that exosomal miRNAs have diagnostic potential in active tuberculosis. The diagnostic power may be improved when combined with conventional diagnostic markers.

Clinical Characteristics and Radiologic Features of Immunocompromised Patients With Pauci-Bacillary Pulmonary Tuberculosis Receiving Delayed Diagnosis and Treatment

Background

Pauci-bacillary pulmonary tuberculosis (TB) can be delayed to diagnose and start anti-TB therapy, especially in immunocompromised patients. We therefore evaluated the clinical and radiologic features of these delayed cases.

Methods

Immunocompromised adult patients with pauci-bacillary pulmonary TB were retrospectively enrolled in a tertiary hospital in an intermediate–TB burden country over a 5-year period. We defined “missed TB” or “not-missed TB” patients as those who started anti-TB therapy after or before positive mycobacterial culture results, respectively.

Results

Of 258 patients, 134 (52%) were classified in the missed TB group, and 124 (48%) in the not-missed TB group. Positive results of molecular tests including MTB polymerase chain reaction and/or Xpert TB/RIF were only obtained in the not-missed TB group (54/106, 54%). The median diagnostic delay in the missed TB group was longer than in the other group (30 vs 6 days; P < .001). In the missed TB group, the most common working diagnoses were pneumonia (46, 34%) and lung metastasis of malignancy (40, 30%). Typical radiologic findings for TB, such as upper lobe predominance and centrilobular nodules with tree-in-bud appearance, were less common in the missed TB group than in the other group. Old age (odds ratio [OR], 1.03), solid organ transplant (OR, 3.46), solid tumor (OR, 3.83), and hematologic malignancy (OR, 4.04) were independently associated with missed TB.

Conclusions

Care is needed to differentiate pauci-bacillary TB, especially in immunocompromised patients with the mentioned risk factors, even without the usual radiologic features of TB. Additional rapid diagnostic tests to rule out pauci-bacillary TB are urgently needed.

Medical management of drug-sensitive active thoracic tuberculosis: the work-up, radiographic findings and treatment

Tuberculosis (TB) infection and disease have plagued human civilization across time and led to immeasurable morbidity and mortality. This review article focuses on the most currently available information regarding the diagnostic workup, radiologic presentation and treatment of drug-sensitive active TB. As discussed, if adequate resources and methods are available to diagnose, evaluate, and treat patients, drug sensitive TB is an imminently curable disease.

Spatial and temporal evolution of lung granulomas in a cynomolgus macaque model of Mycobacterium tuberculosis infection

BACKGROUND

Little is known about granuloma progression of Mycobacterium tuberculosis infection in humans. Using serial positron emission tomography and computed tomography (PET/CT) of an animal model that recapitulates human infection with M. tuberculosis, we are able to track lung granulomas.

OBJECTIVE

We characterized the spatial and temporal pattern of granuloma formation during primary infection and reactivation.

METHODS

Serial PET/CT was performed on cynomolgus macaques (n = 28) during primary and reactivation M. tuberculosis infection. Distances between granulomas during the first six weeks post infection ("primary" granulomas) were compared to new granulomas that developed afterwards ("secondary" granulomas) using nearest neighbor analysis during primary infection, reactivation and between different routes of infection.

RESULTS

Secondary granulomas developed within 2 cm of a primary granuloma within the same lung lobe with 80% probability during the course of primary infection, and this same pattern was observed during reactivation of latent infection after immune suppression. Using a logistic growth function, we were able to predict the maximum number of granulomas that would develop over the course of infection with good correlation (R² = 0.96).

CONCLUSION

These data provide important insights into the dynamic patterns of bacterial dissemination during the earliest phases of primary infection and reactivation tuberculosis.

[Thoracic manifestation of tuberculosis]

CLINICAL ISSUE

Tuberculosis (TB) is a granulomatous disease caused by Mycobacterium tuberculosis and transmission is via an airborne route by droplet infection. In the majority of cases patients have thoracic TB, which most frequently presents with hilar lymphadenopathy and pulmonary manifestation. Due to the rise in incidence of TB in central Europe to be expected over the coming years, it is essential to be acquainted with the radiological manifestations of pulmonary TB, particularly to be able to discriminate active from inactive TB. Due to the use of molecular techniques entailing DNA fingerprinting, the traditional classification of TB in primary and postprimary TB is being challenged. These genetic studies have revealed that variations in the clinical and radiographic appearance of TB are mainly affected by the immune status of the patients. Due to the low prevalence of TB in central Europe and the wide variation of radiological presentations, the diagnosis and therapy of TB is often delayed. In this article, the radiographic manifestations of thoracic TB are summarized and discussed.

STANDARD RADIOLOGICAL METHODS

Together with the medical history and bacteriological tests, chest X‑ray imaging and computed tomography (CT) play a major role not only in the detection of TB but also in the follow-up during and after therapy.

PRACTICAL RECOMMENDATIONS

Chest X‑radiographs should be the primary diagnostic method in patients with suspected TB in screening as well as for diagnosis and therapy monitoring. The use of CT is more sensitive than chest radiographs and is frequently performed after chest radiographs to obtain detailed information about subtle parenchymal changes or lymph node manifestation. When active TB is suspected CT should be performed. Tree in bud, lobular consolidations, centrilobular nodules, cavities and ground-glass opacification are typical changes in active TB.

Pulmonary Tuberculosis in Patients With Emphysema: Computed Tomography Findings

OBJECTIVE

To evaluate the computed tomography (CT) findings and clinical characteristics of pulmonary tuberculosis (TB) in patients with emphysema, compared with those without emphysema.

MATERIALS AND METHODS

Thirty-nine patients (M:F = 36:3; mean age, 64.8 years) who were diagnosed with chronic obstructive pulmonary disease and had emphysema in pretreatment chest CT scans were included in this study (emphysema group). Their clinical presentation, laboratory findings, and CT findings were compared with those of 57 pulmonary TB patients without chronic obstructive pulmonary disease and emphysema (M:F = 52:5; mean age, 64.3 years) (nonemphysema group).

RESULTS

Fever was a more frequent clinical presentation and the C-reactive protein level was higher in the emphysema group. Among CT findings, consolidation and ground-glass opacity were seen more frequently in the emphysema group (82% and 69% vs 42% and 19%, respectively, P < 0.001). Consolidation was more often nonsegmental than lobular or segmental. Tree-in-bud appearance was less frequently noted in the emphysema group (36% vs 79%, P < 0.001). The location of main lesions (upper lung vs middle/lower lung) was not different between the 2 groups.

CONCLUSIONS

Pulmonary TB in emphysema patients often shows bacterial pneumonia-like features, that is, presence of consolidation and ground-glass opacity and lack of bronchogenic spread on chest CT scans, combined with the presence of fever and a high C-reactive protein level. Sputum smear for acid-fast bacteria should be performed early in emphysema patients with pneumonia in TB-endemic areas.

Diagnostics for pulmonary tuberculosis

Tuberculosis (TB) remains a leading cause of human suffering and mortality despite decades of effective treatment being available. Accurate and timely diagnosis remains an unmet goal. The HIV epidemic has also led to new challenges in the diagnosis of TB. Several new developments in TB diagnostics have the potential to positively influence the global campaign against TB. We aim to review the performance of both established as well as new diagnostics for pulmonary TB in adults, and discuss the ongoing challenges.

CT and microbiologic follow-up in primary multidrug-resistant pulmonary tuberculosis

BACKGROUND

Little attention has been paid to the initial and follow-up computed tomography (CT) features in primary multi-drug resistant tuberculosis (pMDR-TB) setting.

PURPOSE

To describe serial CT findings and clinical course of pMDR-TB with antibiotic treatment.

MATERIAL AND METHODS

For the last 10 years, 340 MDR-TB patients were managed in a tertiary referral hospital. Among them, we included 44 (27 men, 17 women; mean age, 40 years; age range, 20-81 years) pMDR-TB patients; 37 treated with chemotherapy only and seven treated with medical therapy plus surgery. CT findings were evaluated regarding tree-in-bud sign, acinar nodule, peribronchial, segmental or lobar consolidation and cavity, and their extent. Sputum negative conversion rates and serial CT scores were assessed. To compare changes in disease extent between initial and follow-up CT studies, paired t-test was performed.

RESULTS

Two most frequent patterns of lung abnormality were tree-in-bud sign (37 of 44, 84.1%) and acinar nodule (41 of 44, 93.2%). Among 37 patients treated with chemotherapy only, 36 showed negative sputum conversion within 3 months after second-line drug commencement, maintained for >12 months. The other seven undergoing surgery during medical treatment showed excellent outcome with negative conversion achieved within one month after surgery and maintained for >12 months. CT scores showed significant decrease on serial CT studies (P < 0.001) in all.

CONCLUSION

In pMDR-TB, two most frequent abnormal CT patterns are tree-in-bud sign and acinar nodule. In 98% of patients, negative sputum conversion is achieved, and CT score also shows decrease in extent after TB chemotherapy.

Infection

Community-Acquired Pneumonia (CAP) is the first leading cause of death due to infection worldwide.Many gram-positive, gram-negative bacteria, funguses and viruses can cause the infectious pulmonary disease, and the severity of pneumonia depends on the balance between the microorganism charge, the body immunity defenses and the quality of the underlying pulmonary tissue. The microorganisms may reach the lower respiratory tract from inhaled air or from infected oropharyngeal secretions. The same organism may produce several different patterns that depend on the balance between the microorganism charge and the body immunity defenses.CAP is classified into three main groups: lobar pneumonia, bronchopneumonia and interstitial pneumonia.Lobar pneumonia is characterized by the filling of alveolar spaces by edema full of white and inflammatory cells. Necrotizing pneumonia consists of a fulminant process associated with focal areas of necrosis that results in abscesses. Bronchopneumonia or lobular pneumonia, is characterized by a peribronchiolar inflammation with thickening of peripheral bronchial wall, the diffusion of inflammation to the centrilobular alveolar spaces and development of nodules.The interstitial pneumonia represents with the destruction and esfoliation of the respiratory ciliated and mucous cells. The interstitial septa, the bronchial and bronchiolar walls become thickened for the inflammation process and lymphocytes interstitial infiltrates.Chest radiography represents an important initial examination in all patients suspected of having pulmonary infection and for monitoring response to therapy.Its role is to identify the pulmonary opacities, their internal characteristics and distribution, pleural effusion and presence of other complications as abscesses and pneumothorax.High spatial CT resolution allows accurate assessment of air space inflammation.The CT findings include nodules, interlobular septal thickening, intralobular reticular opacities, ground-glass opacities, tree-in-bud pattern, lobar-segmental consolidation, lobular consolidation, abscesses, pneumatocele, pleural effusion, pericardial effusion, mediastinal and hilar lymphoadenopaties, airway dilatation and emphysema.

Immunology studies in non-human primate models of tuberculosis

Non-human primates, primarily macaques, have been used to study tuberculosis for decades. However, in the last 15 years, this model has been refined substantially to allow careful investigations of the immune response and host-pathogen interactions in Mycobacterium tuberculosis infection. Low-dose challenge with fully virulent strains in cynomolgus macaques result in the full clinical spectrum seen in humans, including latent and active infection. Reagents from humans are usually cross-reactive with macaques, further facilitating the use of this model system to study tuberculosis. Finally, macaques develop the spectrum of granuloma types seen in humans, providing a unique opportunity to investigate bacterial and host factors at the local (lung and lymph node) level. Here, we review the past decade of immunology and pathology studies in macaque models of tuberculosis.

A Novel Reading Scheme for Assessing the Extent of Radiographic Abnormalities and Its Association with Disease Severity in Sputum Smear-Positive Tuberculosis: An Observational Study in Hyderabad/India

Background

Existing reading schemes for chest X-ray (CXR) used to grade the extent of disease severity at diagnosis in patients with pulmonary tuberculosis (PTB) are often based on numerical scores that summate specific radiographic features. However, since PTB is known to exhibit a wide heterogeneity in pathology, certain features might be differentially associated with clinical parameters of disease severity.

Objective

We aimed to grade disease severity in PTB patients at diagnosis and after completion of DOTS treatment by developing a reading scheme based on five different radiographic manifestations and analyze their association with the clinical parameters of systemic involvement and infectivity.

Methods

141 HIV-negative adults with newly diagnosed sputum smear-positive PTB were enrolled in a prospective observational study in Hyderabad, India. The presence and extent on CXRs of five radiographic manifestations, i.e., lung involvement, alveolar infiltration, cavitation, lymphadenopathy and pleural effusion, were classified using the new reading scheme by using a four-quadrant approach. We evaluated the inter-reader reliability of each manifestation, and its association with BMI and sputum smear positivity at diagnosis. The presence and extent of these radiographic manifestations were further compared with CXRs on completion of DOTS treatment.

Results

At diagnosis, an average lung area of 51.7% +/- 23.3% was affected by radiographic abnormalities. 94% of the patients had alveolar infiltrates, with 89.4% located in the upper quadrants, suggesting post primary PTB and in 34.8% of patients cavities were found. We further showed that the extent of affected lung area was a negative predictor of BMI (β value -0.035, p 0.019). No significant association of BMI with any of the other CXR features was found. The extent of alveolar infiltrates, along with the presence of cavitation, were strongly associated with sputum smear positivity. The microbiological cure rate in our cohort after 6 months of DOTS treatment was 95%. The extent of the affected lung area in these patients decreased from 56.0% +/- 21.5% to 31.0 +/- 20% and a decrease was also observed in the extent of alveolar infiltrates from 98.4% to 25.8% in at least one quadrant, presence of cavities from 34.8% to 1.6%, lymphadenopathy from 46.8% to 16.1%, and pleural effusion from 19.4% to 6.5%.

Conclusions

We established a new assessment scheme for grading disease severity in PTB by specifically considering five radiographic manifestations which were differently associated with the BMI and sputum smear positivity, changed to a different extent after 6 months of treatment and exhibited an excellent agreement between radiologists. Our results suggest that this reading scheme might contribute to the estimation of disease severity with respect to differences in disease pathology. Further studies are needed to determine a correlation with short and long-term pulmonary function impairment and whether there would be any benefit in lengthening or modulating therapy based on this CXR severity assessment.

Innate and Adaptive Cellular Immune Responses to Mycobacterium tuberculosis Infection

Host resistance to Mycobacterium tuberculosis (Mtb) infection requires the coordinated efforts of innate and adaptive immune cells. Diverse pulmonary myeloid cell populations respond to Mtb with unique contributions to both host-protective and potentially detrimental inflammation. Although multiple cell types of the adaptive immune system respond to Mtb infection, CD4 T cells are the principal antigen-specific cells responsible for containment of Mtb infection, but they can also be major contributors to disease during Mtb infection in several different settings. Here, we will discuss the role of different myeloid populations as well as the dual nature of CD4 T cells in Mtb infection with a primary focus on data generated using in vivo cellular immunological studies in experimental animal models and in humans when available.

Radiographic appearance of pulmonary tuberculosis: dogma disproved

OBJECTIVE

The purpose of this article is to review the origins of the classic teaching on pulmonary tuberculosis, its evolution in the modern literature, and the evidence that led to its demise.

CONCLUSION

Use of molecular epidemiologic techniques that entail DNA finger-printing has led to the discovery that the radiographic appearance of pulmonary tuberculosis does not depend on the time since infection. It has been confirmed that the upper lobe cavitary disease typical in adults is the disease of the immunocompetent host, whereas lower lung zone disease, adenopathy, and effusions, which are uncommon in adults, are the hallmarks of tuberculosis in an immunocompromised host.

Diagnosis of pulmonary tuberculosis: recent advances and diagnostic algorithms

Pulmonary tuberculosis (TB) persists as a great public health problem in Korea. Increases in the overall age of the population and the rise of drug-resistant TB have reinforced the need for rapid diagnostic improvements and new modalities to detect TB and drug-resistant TB, as well as to improve TB control. Standard guidelines and recent advances for diagnosing pulmonary TB are summarized in this article. An early and accurate diagnosis of pulmonary TB should be established using chest X-ray, sputum microscopy, culture in both liquid and solid media, and nucleic acid amplification. Chest computed tomography, histopathological examination of biopsy samples, and new molecular diagnostic tests can be used for earlier and improved diagnoses, especially in patients with smear-negative pulmonary TB or clinically-diagnosed TB and drug-resistant TB.

Pulmonary Tuberculosis Confirmed by Percutaneous Transthoracic Needle Biopsy: Analysis of CT Findings and Review of Correlations with Underlying Lung Disease

BACKGROUND

Pulmonary tuberculosis (TB) can produce unusual radiographic findings. Further, negative sputum and bronchoscopic results are common. Early diagnosis is equally as significant as treatment in the reduction of morbidity and mortality associated with pulmonary TB.

AIMS

The aim of this study was to assess computed tomography (CT) findings of pulmonary TB, confirmed via percutaneous transthoracic needle biopsy (PTNB), and to correlate these findings with coexisting, underlying, lung diseases if present.

STUDY DESIGN

Cross sectional study.

METHODS

We selected eighty-four patients who were diagnosed with pulmonary TB by way of PTNB. Initially, acid-fast bacilli smear test results from these patients were negative. CT findings were reviewed to detect the presence of parenchymal abnormalities as follows: nodule(s) (<3 cm in diameter), mass (any masses ≥3 cm), daughter nodules, air-space consolidation, cavitation, calcification, lymphadenopathy, mediastinal lymphadenopathy, and associated lung parenchymal disease.

RESULTS

The CT findings of pulmonary TB confirmed by PTNB included nodules in 44 of 84 (52.4%) cases; 15 of these 44 cases (34.1%) had daughter nodules. The second most common finding was masses in 24 cases (28.6%), nine of which also had daughter nodules. 16 cases (19.0%) displayed nonsegmental consolidation. Of these 16 cases, four had coexisting usual interstitial pneumonia; four others had emphysema. Two patients with a mass had underlying pneumoconiosis.

CONCLUSION

Nodules or a mass mimicking lung cancer were the most common findings on CT scans in patients with pulmonary TB, confirmed via PTNB. The second most common finding was airspace consolidation. Therefore, PNTB is useful for the accurate diagnosis of pulmonary TB in the following cases: airspace consolidation or mass associated with underlying usual interstitial pneumonia, emphysema mimicking lung malignancy or cases of bacterial pneumonia.

Tuberculosis: an overview

Tuberculosis (TB) is still a public health issue; it continues to reign as one of the world's deadliest diseases. One-third of the world's population has been infected with TB. Identified cases of mycobacterium must be notified in an attempt to reduce the public health impact of TB on the population. TB transmission occurs via inhalation of droplet nuclei. The most common site for the development of TB is the lungs. Treatment of TB depends on whether latent TB or active TB is treated.

Is tuberculosis a lymphatic disease with a pulmonary portal?

Tuberculosis most commonly presents as a pulmonary disease, in which infection, persistence, and induction of transmissible pathology all occur in the lungs. If viewed as a pulmonary disease, enlarged lymph nodes represent reactive adenitis, and extrapulmonary forms of tuberculosis (including lymphatic tuberculosis) are not transmissible, hence representing an evolutionary dead-end for the pathogen. In an alternative theory, Mycobacterium tuberculosis passes asymptomatically through the lungs and rapidly establishes a chronic lymphatic infection. After a period of weeks to decades secondary lung pathology develops, ultimately allowing transmission to occur. Evidence that supports this lymphatic model includes historical descriptions of human tuberculosis from the preantibiotic era, analogy with other mycobacterial infections, observations of tuberculosis in non-human hosts, and experimental models of tuberculosis disease. At a fundamental level, a lymphocentric model proposes that spread of organisms outside the lung parenchyma is essential to induce adaptive immunity, which is crucial for the generation of transmissible pathology. Furthermore, a lymphatic model could explain why the lesion associated with primary infection (Ghon focus) is anatomically separated from the most common site of reactivation disease (the apex). More practically, an alternative perspective that classes tuberculosis as a lymphatic disease might affect strategies for preclinical and clinical assessment of novel diagnostics, drugs, and vaccines.

Chest radiograph findings and time to culture conversion in patients with multidrug-resistant tuberculosis and HIV in Tugela Ferry, South Africa

Background

The majority of patients with multidrug-resistant tuberculosis (MDR-TB) in South Africa are co-infected with HIV, but the radiographic features of MDR-TB and their relationship with time to sputum culture conversion in the antiretroviral therapy era have not been described.

Methods

We reviewed baseline chest radiographs for 56 patients with MDR-TB from a rural area of South Africa. We analyzed the association of cavities, consolidation, pleural effusion and hilar lymphadenopathy with time to sputum culture conversion, adjusting for HIV status, baseline sputum smear and CD4 count.

Results

Of the 56 subjects, 49 (88%) were HIV-positive, with a median CD4 count of 136 cells/mm³ (IQR 65-249). Thirty-two (57%) patients were sputum smear positive. Twenty-two (39%) patients had a cavity and 37 (66%) patients had consolidations. Cavitary disease and consolidations were each associated with longer time to culture conversion on bivariate analysis but not after adjusting for sputum smear status (aORs 1.79 [0.94-3.42] and 1.09 [0.67-1.78], respectively). Positive baseline sputum smear remained independently associated with longer time to conversion (aOR 3.45 [1.39-8.59]). We found no association between pleural effusion or hilar lymphadenopathy and time to conversion. Seventy-nine percent of patients were cured at the end of treatment.

Conclusions

Despite high rates of HIV co-infection and advanced immunodeficiency, the majority of patients had severe pathology on baseline chest radiograph. Nevertheless, culture conversion rates were high and treatment outcomes were favorable. Cavitation and consolidation do not appear to have an independent association with time to culture conversion beyond that of baseline sputum smear status.

Macrophages and control of granulomatous inflammation in tuberculosis

The granuloma that forms in response to Mycobacterium tuberculosis must be carefully balanced in terms of immune responses to provide sufficient immune cell activation to inhibit the growth of the bacilli, yet modulate the inflammation to prevent pathology. There are likely many scenarios by which this balance can be reached, given the complexity of the immune responses induced by M. tuberculosis. In this review, we focus on the key role of the macrophage in balancing inflammation in the granuloma.

A spotlight on liquefaction: evidence from clinical settings and experimental models in tuberculosis

Liquefaction is one of the most intriguing aspects of human tuberculosis. It is a major cause of the transition from the infection to active disease (tuberculosis, TB) as well as the transmission of M. tuberculosis to other persons. This paper reviews the natural history of liquefaction in humans from a pathological and radiological point of view and discusses how the experimental models available can be used to address the topic of liquefaction and cavity formation. Different concepts that have been related to liquefaction, from the influence of immune response to mechanical factors, are reviewed. Synchronic necrosis or apoptosis of infected macrophages in a close area, together with an ineffective fibrosis, appears to be clue in this process, in which macrophages, the immune response, and bacillary load interact usually in a particular scenario: the upper lobes of the lung. The summary would be that even if being a stochastic effect, liquefaction would result if the organization of the intragranulomatous necrosis (by means of fibrosis) would be disturbed.

Pulmonary involvement in pleural tuberculosis: how often does it mean disease activity?

OBJECTIVE

To evaluate in chest X-rays and high-resolution computed tomographies of patients with pleural tuberculosis, the incidence of parenchymal and mediastinal lung lesions suggestive of active disease.

METHODS

Prospective study (2008-2009) evaluating the radiographic and tomographic abnormalities of 88 HIV-negative patients with pleural tuberculosis (unilateral effusion). The images were reviewed by 3 independent specialists, and the observed changes were classified according to previously established criteria: presence or absence of signs suggestive of disease activity, and nonspecific findings.

RESULTS

Abnormal changes were observed in chest X-rays of 22 (25%) patients and in the computed tomography of 55 (63%). Images compatible with active pulmonary tuberculosis were detected by radiography in 9 (10%) patients and by tomography in 38 (43%). Only 4 (4.5%) patients had tomography images suggestive of residual disease.

CONCLUSION

The present study demonstrates that pulmonary involvement is quite common in pleural tuberculosis. This finding is mainly observed in high-resolution computed tomography and has important epidemiological implications, since patients with pleural tuberculosis are significant sources of infection and disease dissemination.

Aspectos tomográficos da tuberculose pulmonar em pacientes adultos com AIDS

OBJETIVO: Este trabalho tem como finalidade descrever os achados tomográficos da tuberculose pulmonar em pacientes adultos com AIDS atendidos no serviço de radiologia de um hospital de referência em doenças infecciosas, procurar associações desses achados e a contagem de CD4. MATERIAIS E MÉTODOS: Foram estudados 45 pacientes por meio de tomografia computadorizada de tórax durante quatro anos. RESULTADOS: Foram encontrados linfonodomegalia mediastinal e/ou hilar em 31 (68,8%) dos casos, derrame pleural em 29 (64,4%), nódulos centrolobulares de distribuição segmentar em 26 (57,7%), consolidação em 24 (53,3%), confluência de micronódulos em 17 (37,7%), nódulos mal definidos com distribuição centrolobular em 16 (35,5%), padrão de "árvore em brotamento" em 13 (28,9%), espessamento de parede brônquica em 12 (26,6%), cavidade de parede espessa em 10 (22,2%), nódulos miliares em 9 (20%) e bronquiectasias cilíndricas em 6 (13,3%). Dos 45 pacientes, 35 (77,8%) apresentaram CD4 < 200 cel/mm³ e 10 (22,2%) apresentaram CD4 > 200 cel/mm³. CONCLUSÃO: Concluímos que neste estudo, diversamente do descrito na literatura, linfonodomegalia mediastinal e/ou hilar e consolidação foram significativamente mais frequentes em pacientes com CD4 > 200 cel/mm³. No entanto, linfonodos com centro hipodenso foram mais frequentemente observados em pacientes com severa imunodepressão, ou seja, CD4 < 200 cel/mm³.

Chest radiographic findings in primary pulmonary tuberculosis: observations from high school outbreaks

Objective

To describe the radiographic findings of primary pulmonary tuberculosis (TB) in previously healthy adolescent patients.

Materials and Methods

The Institutional Review Board approved this retrospective study, with a waiver of informed consent from the patients. TB outbreaks occurred in 15 senior high schools and chest radiographs from 58 students with identical strains of TB were analyzed by restriction fragment length polymorphism analysis by two independent observers. Lesions of nodule(s), consolidation, or cavitation in the upper lung zones were classified as typical TB. Mediastinal lymph node enlargement; lesions of nodule(s), consolidation, or cavitation in lower lung zones; or pleural effusion were classified as atypical TB. Inter-observer agreement for the presence of each radiographic finding was examined by kappa statistics.

Results

Of 58 patients, three (5%) had normal chest radiographs. Cavitary lesions were present in 25 (45%) of 55 students. Lesions with upper lung zone predominance were observed in 27 (49%) patients, whereas lower lung zone predominance was noted in 18 (33%) patients. The remaining 10 (18%) patients had lesions in both upper and lower lung zones. Pleural effusion was not observed in any patient, nor was the mediastinal lymph node enlargement. Hilar lymph node enlargement was seen in only one (2%) patient. Overall, 37 (67%) students had the typical form of TB, whereas 18 (33%) had TB lesions of the atypical form.

Conclusion

The most common radiographic findings in primary pulmonary TB by recent infection in previously healthy adolescents are upper lung lesions, which were thought to be radiographic findings of reactivation pulmonary TB by remote infection.

Strengths and weaknesses of diagnostic tools for tuberculous uveitis

Diagnostic criteria for tuberculous uveitis encompass exclusion of other known etiologies of uveitis, suggestive clinical history and signs, supportive systemic investigations, positive response to empiric antituberculosis treatment and evidence of Mycobacterium tuberculosis or its DNA in ocular fluids/tissues. Recent advances in diagnostic tools for tuberculous infection, including molecular biology techniques for detection of M. tuberculosis DNA and interferon-gamma release assays, have improved the specificity of the diagnosis and the ability to ascertain exposure to the infectious agent. However even with such advances, establishing the diagnosis of tuberculous uveitis remains a challenging issue because each of these available investigations has its strengths and limitations and tuberculous infection can present with clinical features of any type of extraocular or intraocular inflammation. This article critically analyzes the role of these tests in supporting the diagnosis of tuberculous uveitis and proposes a practical diagnostic approach, based on a judicious combination of these tests.

Pulmonary tuberculosis: up-to-date imaging and management

OBJECTIVE

Pulmonary tuberculosis (TB) is a common worldwide infection and a medical and social problem causing high mortality and morbidity, especially in developing countries. The traditional imaging concept of primary and reactivation TB has been recently challenged, and radiologic features depend on the level of host immunity rather than the elapsed time after the infection. We aimed to elaborate the new concept of the diagnosis and treatment of pulmonary TB, to review the characteristic imaging findings of various forms of pulmonary TB, and to assess the role of CT in the diagnosis and management of pulmonary TB.

CONCLUSION

Fast and more accurate TB testing such as bacterial DNA fingerprinting and whole-blood interferon-gamma assay has been developed. Miliary or disseminated primary pattern or atypical manifestations of pulmonary TB are common in patients with impaired immunity. CT plays an important role in the detection of TB in patients in whom the chest radiograph is normal or inconclusive, in the determination of disease activity, in the detection of complication, and in the management of TB by providing a roadmap for surgical treatment planning. PET scans using 18F-FDG or 11C-choline can sometimes help differentiate tuberculous granuloma from lung malignancy.

Clinical and radiographic features of HIV-related pulmonary tuberculosis according to the level of immunosuppression

Medical charts and radiographs from 38 HIV-infected patients with positive cultures for Mycobacterium tuberculosis from sputum or bronchoalveolar lavage were reviewed in order to compare the clinical, radiographic, and sputum bacilloscopy characteristics of HIV-infected patients with pulmonary tuberculosis according to CD4+ lymphocyte count (CD4). The mean age of the patients was 32 years and 76% were male. The median CD4 was 106 cells/mm(3) and 71% had CD4 < 200 cells/mm(3). Sputum bacilloscopy was positive in 45% of the patients. Patients with CD4 < 200 cells/mm(3) showed significantly less post-primary pattern (7% vs. 63%; p = 0.02) and more frequently reported weight loss (p = 0.04). Although not statistically significant, patients with lower CD4 showed lower positivity of sputum bacilloscopy (37% vs. 64%; p = 0.18). HIV-infected patients with culture-confirmed pulmonary tuberculosis had a high proportion of non-post-primary pattern in thoracic radiographs. Patients with CD4 lower than 200 cells/mm(3) showed post-primary patterns less frequently and reported weight loss more frequently.

The prevalence of pulmonary parenchymal tuberculosis in patients with tuberculous pleuritis

STUDY OBJECTIVE

To examine the prevalence and characteristics of parenchymal tuberculous pleuritis in adult patients.

DESIGN

Prospective cohort study.

SETTING

Three hospitals affiliated with Seoul National University in South Korea.

PATIENTS

All patients > 15 years old with a diagnosis of tuberculous pleuritis were enrolled prospectively between January 1, 2004, and October 31, 2004.

INTERVENTIONS

Diagnostic thoracocentesis and CT of the chest were done for each patient. Acid-fast bacilli (AFB) smears and cultures for Mycobacterium tuberculosis were requested if patients produced any sputum. A board-certified radiologist reviewed the chest radiographs for the presence and characteristics of any lesions.

MEASUREMENTS AND RESULTS

One hundred six patients with tuberculous pleuritis were enrolled (median age, 53 years; range 16 to 89 years). Among them, 33 patients (31%) had sputum or bronchial washing findings positive for AFB smears or for M tuberculosis by culture. Lung parenchymal lesions were observed in 91 of the patients (86%) using chest CT; 39 patients (37%) with parenchymal lesions had radiographic characteristics of active pulmonary tuberculosis. In total, 62 patients (59%) had bacteriologically or radiographically active pulmonary tuberculosis. In addition, 78 patients (74%) had features of reactivated pulmonary tuberculosis.

CONCLUSIONS

Lung parenchymal lesions were more common in this series of patients with tuberculous pleuritis than has been reported in previous studies. The patients mostly had radiographic features of reactivated, rather than primary, tuberculosis.

Padrões radiológicos da tuberculose pulmonar em indígenas Suruí de Rondônia, Amazônia

Foram analisados padrões radiológicos de 23/33 (69,7%) dos indígenas Suruí tratados em 2003-2004. Observou-se 44,8% de consolidações não homogêneas, 10,3% de cavitações e 39,1% de acometimentos múltiplos do parênquima. Apesar de 36% dos doentes avaliados terem apresentado radiografias normais, o tratamento específico foi iniciado sem que tivessem sido esgotadas as possibilidades de investigação diagnóstica.

Tuberculosis in sub-Saharan Africa: opportunities, challenges, and change in the era of antiretroviral treatment

Rapid scale-up of antiretroviral treatment programmes is happening in Africa, driven by international advocacy and policy directives and supported by unprecedented donor funding and technical assistance. This welcome development offers hope to millions of HIV-infected Africans, among whom tuberculosis is the major cause of serious illness and death. Little in the way of HIV diagnosis or care was previously offered to patients with tuberculosis, by either national tuberculosis or AIDS control programmes, with tuberculosis services focused exclusively on diagnosis and treatment of rising numbers of patients. Tuberculosis control in Africa has yet to adapt to the new climate of antiretroviral availability. Many barriers exist, from drug interactions to historic differences in the way that tuberculosis and HIV are perceived, but failure to successfully integrate HIV and tuberculosis control will threaten the viability of both programmes. Here, we review tuberculosis epidemiology in Africa and policy implications of HIV/AIDS treatment scale-up.

What's good for the host is good for the bug

Tuberculosis, caused by Mycobacterium tuberculosis, kills approximately two million people each year. The infection is characterized by an inflammatory response culminating in the formation of a granuloma, a collection of immune cells that controls the infection. However, the granuloma can be the source of immunopathology that encourages transmission. Recent data support the idea that mycobacterial products can positively and negatively regulate the inflammatory response. Our contention is that induction of the immune response and subsequent granuloma formation is beneficial to the host for control of infection, and is also beneficial to the bacillus, as a place to hide and as a means for transmitting the infection to naive hosts.

Tuberculosis in patients with HIV infection

In the past 5 years, there have been significant advances in the understanding of the pathogenesis of TB in people infected with HIV and in the approach to diagnosis, treatment, and prevention in patients with HIV. Nucleic acid amplification tests and restriction fragment length polymorphism can contribute to the clinical management of TB patients. New guidelines are available for the treatment of active and latent TB infection in patients with HIV.

Tuberculosis control in a border state. Treatment of the foreign-born

As the epidemiology of TB in the United States changes, with more foreign-born and fewer native-born residents developing the disease, treatment can be expected to become more complicated and expensive.

Biosynthesis, characterisation, and design of bacterial exopolysaccharides from lactic acid bacteria

Lactic acid bacteria (LAB) are characterised by their conversion of a large proportion of their carbon feed, fermentable sugars, to lactic acid. However, in addition to lactic acid production, the LAB are able to divert a small proportion of fermentable sugars towards the biosynthesis of exopolysaccharides (EPSs) that are independent of the cell surface and cell wall material. These microbial EPSs when suspended or dissolved in aqueous solution provide thickening and gelling properties, and, as such, there is great interest in using EPSs from food grade microorganisms (such as the LAB that are traditionally used for food fermentations) for use as thickening agents. The current review includes a brief summary of the recent literature describing features of the biosynthetic pathways leading to EPS production. Many aspects of EPS biosynthesis in LAB are still not fully understood and a number of inferences are made regarding the similarity of the pathway to those involved in the synthesis of other cell polysaccharides, e.g., cell wall components. The main body of the review will cover practical aspects concerned with the isolation and characterisation of EPS structures. In the last couple of years, a substantial number of structures have been published and a summary of the common elements of these structures is included as is a suggestion for a system for representing structures. A brief highlight of the attempts that are being made to design 'tailor'-made polysaccharides using genetic modification and control of metabolic flux is presented.

Radiographic features of pulmonary tuberculosis in patients infected by HIV: is there an objective indicator of co-infection?

This study aimed to compare the radiographic characteristics of patients with pulmonary tuberculosis (TB) and human immunodeficiency virus (HIV) infection with those of HIV-negative patients. In all, 275 TB patients attending the outpatients clinics at the University Hospital/UFPE, were studied from January 1997 to March 1999. Thirty nine (14.2%) of them were HIV(+), with a higher frequency of males in this group (p=0.044). Seventy-five percent of the HIV(+) patients and 19% of the HIV(-) had a negative tuberculin test (PPD) (p < 0.001). The proportion of positive sputum smears in the two groups was similar. The radiological finding most strongly associated with co-infection was absence of cavitation (p < 0.001). It may therefore be concluded that the lack of cavitation in patients with pulmonary TB may be considered a useful indicator of the need to investigate HIV infection. This approach could contribute to increasing the effectiveness of local health services, by offering appropriate treatment to co-infected patients.