The Role of Chest CT Scanning in TB Outbreak Investigation

Lee, Sei Won; Jang, Yoon-Soo; Park, Chang Min; Kang, Hee Yoon; Koh, Won Jung; Yim, Jae Joon; Jeon, Kyeongman

doi:10.1378/chest.09-1513

Cited by 65 publications

(41 citation statements)

References 28 publications

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“…None of the other participants left their platoon for holiday before IGRA conversion. Furthermore, the possibility of missing a patient with active TB was minimised by performing LDCT for all contacts, as LDCT has been shown to be superior to a simple CXR for diagnosing active TB [13,14]. Indeed, two patients in the present investigation were diagnosed with active pulmonary TB based on LDCT.…”

Section: Discussionmentioning

confidence: 97%

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Time interval to conversion of interferon-γ release assay after exposure to tuberculosis

Sw¹,

Dk²,

Sh³

et al. 2010

Eur Respir J

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The proper interval for repeating an interferon-c release assay (IGRA) among tuberculosis contacts with initially negative results is unknown. The interval for IGRA conversion after exposure to patients with active pulmonary tuberculosis in an outbreak setting was evaluated.In a platoon of 32 soldiers, four active pulmonary tuberculosis patients, in addition to one index patient, were diagnosed during a contact investigation. For the other 27 contacts, a tuberculin skin test (TST) and QuantiFERON1 TB-Gold In-Tube (QFT-GIT) assay were performed. For soldiers with a negative result on the initial QFT-GIT assay, the test was repeated at 2, 4, 8, 14, 18 and 30 weeks until positive conversion occurred. When conversion was identified, the subject was treated for latent tuberculosis infection.Initially, 17 (63.0%) soldiers gave positive QFT-GIT results, whereas 21 (77.8%) showed positive TST results. Among 10 participants with initially negative QFT-GIT results, three showed conversion at 2 weeks, three at 4 weeks and three at 14 weeks. Conversion did not occur during the 30-week observation period in one contact.Based on the tuberculosis exposure time-points among the contacts, IGRA conversion generally occurred 4-7 weeks after exposure, although it could occur as late as 14-22 weeks after exposure.

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Section: Discussionmentioning

confidence: 97%

“…1). LDCT was included to detect any active lesions that were not identified by CXR [13,14]. The present study was reviewed and approved by the institutional review board of the Armed Forces Medical Command of the Republic of Korea.…”

Section: Study Protocolmentioning

confidence: 99%

Time interval to conversion of interferon-γ release assay after exposure to tuberculosis

Sw¹,

Dk²,

Sh³

et al. 2010

Eur Respir J

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“…Recent evidence from an analysis of host transcriptional responses of latently infected individuals, compared to healthy individuals and individuals with active disease, suggests that a subset of such people are, in fact, experiencing sub-clinical disease [4]. High-resolution computed tomography (HRCT) findings in latently infected individuals likewise suggest a broad range of manifestations, ranging from enlarged lymph nodes to radiologic findings traditionally associated with active disease [5]. Tuberculosis is therefore more usefully thought of as a spectrum of disease, ranging from waning lesions in the process of being sterilized by the host immune system, through subclinical manifestations, to acute, fulminate, symptomatic infections [6].…”

Section: Introductionmentioning

confidence: 99%

Fumarate Reductase Activity Maintains an Energized Membrane in Anaerobic Mycobacterium tuberculosis

et al. 2011

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Oxygen depletion of Mycobacterium tuberculosis engages the DosR regulon that coordinates an overall down-regulation of metabolism while up-regulating specific genes involved in respiration and central metabolism. We have developed a chemostat model of M. tuberculosis where growth rate was a function of dissolved oxygen concentration to analyze metabolic adaptation to hypoxia. A drop in dissolved oxygen concentration from 50 mmHg to 0.42 mmHg led to a 2.3 fold decrease in intracellular ATP levels with an almost 70-fold increase in the ratio of NADH/NAD+. This suggests that re-oxidation of this co-factor becomes limiting in the absence of a terminal electron acceptor. Upon oxygen limitation genes involved in the reverse TCA cycle were upregulated and this upregulation was associated with a significant accumulation of succinate in the extracellular milieu. We confirmed that this succinate was produced by a reversal of the TCA cycle towards the non-oxidative direction with net CO2 incorporation by analysis of the isotopomers of secreted succinate after feeding stable isotope (13C) labeled precursors. This showed that the resulting succinate retained both carbons lost during oxidative operation of the TCA cycle. Metabolomic analyses of all glycolytic and TCA cycle intermediates from 13C-glucose fed cells under aerobic and anaerobic conditions showed a clear reversal of isotope labeling patterns accompanying the switch from normoxic to anoxic conditions. M. tuberculosis encodes three potential succinate-producing enzymes including a canonical fumarate reductase which was highly upregulated under hypoxia. Knockout of frd, however, failed to reduce succinate accumulation and gene expression studies revealed a compensatory upregulation of two homologous enzymes. These major realignments of central metabolism are consistent with a model of oxygen-induced stasis in which an energized membrane is maintained by coupling the reductive branch of the TCA cycle to succinate secretion. This fermentative process may offer unique targets for the treatment of latent tuberculosis.

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“…30 Compared with its diagnostic role in bacterial and viral infections, CT abnormalities can be more specific for diagnosis of mycobacterial disease, and can serve as an adjunct to interferon gamma release assays. 31 Upper lobe predominance of centrilobular nodules is a common early manifestation of tuberculosis when presenting as what was traditionally termed reactivation tuberculosis (Fig. 13).…”

Section: Differentiation Of Pneumonia From Noninfectious Diseasesmentioning

confidence: 99%

Imaging Infection

Ketai

Jordan

Busby

2015

Clinics in Chest Medicine

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Thoracic imaging is widely used to detect lower respiratory tract infections, identify their complications, and aid in differentiating infectious from noninfectious thoracic disease. Less commonly, the combination of imaging findings and a clinical setting can favor infection with a specific organism. This confluence can occur in cases of bronchiectatic nontuberculous mycobacterial infections in immune-competent hosts, invasive fungal disease among neutropenic patients, Pneumocystis jiroveci pneumonia in patients with AIDS, and in cytomegalovirus infections in patients with recent hematopoietic cell transplantation. These specific diagnoses often depend on computed tomography scanning rather than chest radiography alone.

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The Role of Chest CT Scanning in TB Outbreak Investigation

Cited by 65 publications

References 28 publications

Time interval to conversion of interferon-γ release assay after exposure to tuberculosis

Time interval to conversion of interferon-γ release assay after exposure to tuberculosis

Fumarate Reductase Activity Maintains an Energized Membrane in Anaerobic Mycobacterium tuberculosis

Imaging Infection

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