Evaluation of a New Chemiluminescent Immunoassay-Based Interferon-Gamma Release Assay for Detection of Latent Tuberculosis Infection

Background and Objectives: This study aimed to evaluate the performance of a new chemiluminescent immunoassay-based tuberculosis (TB) interferon-gamma release assay (IGRA), AdvanSureI3 TB-IGRA (LG Chem Ltd., Seoul, Republic of Korea), for detecting latent tuberculosis infection in comparison with T-SPOT.TB (Oxford Immunotec, Oxford, UK). Materials and Methods: Between June 2021 and December 2021, 125 non-duplicate blood specimens were collected from adult volunteers; each subject received both tests concurrently. Total agreement and Cohen's kappa coefficient (κ) were used to calculate concordance. The Jonckheere-Terpstra test was used to examine the correlation between interferon-gamma (IFN-γ) levels in AdvanSureI3 TB-IGRA and spot counts in T-SPOT.TB. Results: The IGRA findings of the two assays revealed 90.8% (95% confidence interval [CI] = 84.2-94.8) total agreement with κ of 0.740 (95% CI = 0.595-0.885), showing substantial agreement between the two tests. Additionally, the amount of IFN-γ in AdvanSureI3 TB-IGRA increased with the spot counts in T-SPOT.TB (p < 0.001). Conclusions: Our research revealed that the results of the AdvanSureI3 TB-IGRA were comparable to those of T-SPOT.TB.

Tuberculosis in the Elderly

The tuberculosis (TB) epidemic is most prevalent in the elderly, and there is a progressive increase in the notification rate with age. Most cases of TB in the elderly are linked to the reactivation of lesions that have remained dormant. The awakening of these lesions is attributable to changes in the immune system related to senescence. The mortality rate from tuberculosis remains higher in elderly patients. Symptoms of active TB are nonspecific and less pronounced in the elderly. Diagnostic difficulties in the elderly are common in many diseases but it is important to use all possible techniques to make a microbiological diagnosis. Recognising frailty to prevent loss of independence is a major challenge in dealing with the therapeutic aspects of elderly patients. Several studies report contrasting data about poorer tolerance of TB drugs in this population. Adherence to antituberculosis treatment is a fundamental issue for the outcome of treatment. Decreased completeness of treatment was shown in older people as well as a higher risk of treatment failure.

Interferon Gamma Release Assays for Detection of Latent Mycobacterium tuberculosis in Elderly Hispanics

Background:

Interferon gamma release assays (IGRAs) are used to detect latent Mycobacterium tuberculosis (M.tb) infection (LTBI) in adults, but their performance in older people is not well-established. We evaluated IGRAs for LTBI detection in older Hispanic recent TB contacts (ReC) or community controls (CoC).

Methods:

Cross-sectional assessment of LTBI with T-SPOT.TB and/or QuantiFERON-Gold in-tube or –Plus assay in older (≥60 years) and adult (18–50 years) Hispanic people.

Results:

We enrolled 193 CoC (119 adults, 74 older persons) and 459 ReC (361 adults, 98 older persons). LTBI positivity increased with age in CoC (19%–59%, P<0.001), but was similar in ReC (59%–69%, P=0.329). Older people had lower concordance between IGRAs (kappa 0.465 vs 0.688 in adults) and more inconclusive results (indeterminate/borderline 11.6% vs 5.8% in adults, P=0.012). With simultaneous IGRAs, inconclusive results were resolved as positive or negative with the other IGRA. The magnitude of response to M.tb peptides in IGRAs was similar among age groups, but responsiveness to mitogens was lower in older people.

Conclusions:

IGRAs are suitable for LTBI detection in older people. Discordant and inconclusive findings are more prevalent in older people, but results are resolved when IGRA is repeated with a different IGRA test.

Pulmonary immune responses to Mycobacterium tuberculosis in exposed individuals

BACKGROUND

Blood based Interferon-(IFN)-γ release assays (IGRAs) have a poor predictive value for the development of tuberculosis. This study aimed to investigate the correlation between IGRAs and pulmonary immune responses in tuberculosis contacts in Germany.

METHODS

IGRAs were performed on bronchoalveolar lavage (BAL) cells and peripheral blood from close healthy contacts of patients with culturally confirmed tuberculosis. Cellular BAL composition was determined by flow cytometry. BAL cells were co-cultured with three strains of Mycobacterium tuberculosis (Mtb) and Mtb derived antigens including Purified Protein Derivative (PPD), 6 kD Early Secretory Antigenic Target (ESAT-6) and 10 kD Culture Filtrate Protein (CFP-10). Levels of 29 cytokines and chemokines were analyzed in the supernatants by multiplex assay. Associations and effects were examined using linear mixed-effects models.

RESULTS

There were wide variations of inter-individual cytokine levels in BAL cell culture supernatants. Mycobacterial infection and stimulation with PPD showed a clear induction of several macrophage and lymphocyte associated cytokines, reflecting activation of these cell types. No robust correlation between cytokine patterns and blood IGRA status of the donor was observed, except for slightly higher Interleukin-2 (IL-2) responses in BAL cells from IGRA-positive donors upon mycobacterial infection compared to cells from IGRA-negative donors. Stronger correlations were observed when cytokine patterns were stratified according to BAL IGRA status. BAL cells from donors with BAL IGRA-positive responses produced significantly more IFN-γ and IL-2 upon PPD stimulation and mycobacterial infection than cells from BAL IGRA-negative individuals. Correlations between BAL composition and basal cytokine release from unstimulated cells were suggestive of pre-activated lymphocytes but impaired macrophage activity in BAL IGRA-positive donors, in contrast to BAL IGRA-negative donors.

CONCLUSIONS

In vitro BAL cell cytokine responses to M. tuberculosis antigens or infection do not reflect blood IGRA status but do correlate with stronger cellular responses in BAL IGRA-positive donors. The cytokine patterns observed suggest a pre-activated state of lymphocytes and suppressed macrophage responsiveness in BAL cells from BAL IGRA-positive individuals.

Risk for latent and active tuberculosis in Germany

Purpose

Few individuals that are latently infected with M. tuberculosis latent tuberculosis infection(LTBI) progress to active disease. We investigated risk factors for LTBI and active pulmonary tuberculosis (PTB) in Germany.

Methods

Healthy household contacts (HHCs), health care workers (HCWs) exposed to M. tuberculosis and PTB patients were recruited at 18 German centres. Interferon-γ release assay (IGRA) testing was performed. LTBI risk factors were evaluated by comparing IGRA-positive with IGRA-negative contacts. Risk factors for tuberculosis were evaluated by comparing PTB patients with HHCs.

Results

From 2008–2014, 603 HHCs, 295 HCWs and 856 PTBs were recruited. LTBI was found in 34.5% of HHCs and in 38.9% of HCWs. In HCWs, care for coughing patients (p = 0.02) and longstanding nursing occupation (p = 0.04) were associated with LTBI. In HHCs, predictors for LTBI were a diseased partner (odds ratio 4.39), sexual contact to a diseased partner and substance dependency (all p < 0.001). PTB was associated with male sex, low body weight (p < 0.0001), alcoholism (15.0 vs 5.9%; p < 0.0001), glucocorticoid therapy (7.2 vs 2.0%; p = 0.004) and diabetes (7.8 vs. 4.0%; p = 0.04). No contact developed active tuberculosis within 2 years follow-up.

Conclusions

Positive IGRA responses are frequent among exposed HHCs and HCWs in Germany and are poor predictors for the development of active tuberculosis.

Electronic supplementary material

The online version of this article (doi:10.1007/s15010-016-0963-2) contains supplementary material, which is available to authorized users.

Cytokines and Chemokines in Mycobacterium tuberculosis Infection

Chemokines and cytokines are critical for initiating and coordinating the organized and sequential recruitment and activation of cells into Mycobacterium tuberculosis-infected lungs. Correct mononuclear cellular recruitment and localization are essential to ensure control of bacterial growth without the development of diffuse and damaging granulocytic inflammation. An important block to our understanding of TB pathogenesis lies in dissecting the critical aspects of the cytokine/chemokine interplay in light of the conditional role these molecules play throughout infection and disease development. Much of the data highlighted in this review appears at first glance to be contradictory, but it is the balance between the cytokines and chemokines that is critical, and the "goldilocks" (not too much and not too little) phenomenon is paramount in any discussion of the role of these molecules in TB. Determination of how the key chemokines/cytokines and their receptors are balanced and how the loss of that balance can promote disease is vital to understanding TB pathogenesis and to identifying novel therapies for effective eradication of this disease.

B cell responses in older adults with latent tuberculosis: Considerations for vaccine development

Reactivation of latent tuberculosis (LTBI) is more common among the aging population and may contribute to increased transmission in long-term health care facilities. Difficulties in detecting LTBI due to potential blunting of the tuberculin skin test (TST), and the lowered ability of the elderly to tolerate the course of antibiotics, underscore the need for an effective vaccine. Immuno-senescence reduces the capacity of vaccines to induce sufficient levels of protective immunity against many pathogens, further increasing the susceptibility of the elderly to infectious diseases. We sought to evaluate the response of B cells to Mycobacterium tuberculosis (Mtb) in residents of long-term care facilities to determine the feasibility of using a vaccine to control infection and transmission from reactivated LTBI. Our results demonstrate that although B cell responses were higher in subjects with LTBI, Mtb antigens could stimulate B cell activation and differentiation in vitro in TST negative subjects. B cells from elderly subjects expressed high basal levels of Toll-like receptor (TLR)2 and TLR4 and responded strongly to Mtb ligands with some activation pathways dependent on TLR2. B cells derived from blood, tonsil and spleen from younger subjects responded similarly and to the same magnitude. These results suggest that B cell responses are robust in the elderly and modifications to a TB vaccine, such as TLR2 ligand-based adjuvants, may help increase immune responses to a protective level.

Sensitivity of QuantiFERON-TB GOLD In-Tube for diagnosis of recent versus remote M. tuberculosis infection

The sensitivity of QuantiFERON-TB GOLD In-Tube was measured in 104 subjects with recent (≤2 years) and remote Mycobacterium tuberculosis infection using tuberculin skin test conversion as the reference standard. The sensitivity was not significantly different between the 2 groups (33% versus 20%, P = 0.3). This finding suggests interferon-γ release assays may not be more sensitive for diagnosis of recent than remote infection. Longitudinal studies are needed to validate this finding.

Cost effectiveness of interferon-gamma release assay versus chest X-ray for tuberculosis screening of BCG-vaccinated elderly populations

BACKGROUND

The prevalence of tuberculosis (TB) in the elderly is higher than that in the general population, and elderly populations are considered a high-risk group. Currently, annual TB screening of Bacille Calmette-Guérin (BCG)-vaccinated people aged over 65 years is performed by an annual chest x-ray examination (CXR) in Japan. Interferon-gamma release assays (QuantiFERON-TB Gold and QuantiFERON-TB Gold In-Tube [QFT]) are new alternatives to the tuberculin skin test to diagnose latent TB infection (LTBI) that have no cross-reactivity with the BCG vaccine. We evaluated the cost effectiveness of QFT versus CXR versus no screening in BCG-vaccinated elderly populations.

METHODS

We constructed a Markov model to evaluate the cost effectiveness of QFT, CXR, and no screening. The target population was a hypothetical cohort of 1000 immunocompetent 65-year-olds, using a societal perspective and a lifetime horizon. All costs and clinical benefits were discounted at a fixed annual rate of 3%.

RESULTS

In the base-case analysis, a no-screening strategy resulted in the lowest cost ($US303.51; 14.6475 quality-adjusted life-years [QALYs]) compared with CXR ($US393.22; 14.6477 QALYs) and QFT ($US525.45; 14.6516 QALYs) [year 2008 values]. The sensitivity of QFT, as well as the prevalence of TB and LTBI, influenced the cost effectiveness; when the sensitivity of QFT was higher than 0.89, QFT became more cost effective than providing no screening. As the prevalence of LTBI and TB increased, the QFT strategy became progressively more cost effective.

CONCLUSIONS

Providing no routine TB screening is currently the most cost-effective strategy for BCG-vaccinated elderly populations in Japan. There appears to be little role for CXR in TB screening of elderly populations. These findings may be applicable to other countries with intermediate and high TB risks when choosing optimal TB screening of elderly populations.

Randomized Prospective Study on the Use of Eufiss in the Prevention of Infections in Patients Treated with External Fixation

Percutaneous synthesis using K-wires or external fixation in orthopedics and traumatology is extremely common. Postoperative management of external fixation includes frequent wound care which is demanding for both the patient and the healthcare professionals. In literature the most frequently reported complication is infection. The use of ionic silver goes back to the beginning of the last century and there are many articles describing its antimicrobial efficacy even for antibiotic-resistant bacteria. In this study we assess the reduction in both superficial and deep infections by using ionic silver in patients with external fixation for orthopedic diseases or traumatology. Furthermore, we show how this method could also contribute to reducing wound care costs. The data collected shows an overall infection incidence of 10%, concordant with data in literature. There appears to be no correlation between the probability of superficial infections and predisposing diseases, such as diabetes, nor the fracture site or position. The presence of loose pins increases the probability of infection. There appears to be no correlation between the clinical examination and the microbiological culture. The data analysis shows that wound care with ionic silver reduces the incidence of superficial infection of the pins. Furthermore, this method guarantees greater cleanliness of the skin and the external fixator which increases patient satisfaction in the management of the external fixation. To date, an insufficient number of patients have been studied to gather enough data to establish which wound care method is the most economical. Certainly, we can state that treatment with ionic silver reduces infection incidence and enables better management of the external fixators and percutaneous synthesis in orthopedics and traumatology.

Inter-Relationship between Chemokines and Mast Cells

The inflammatory response is mediated by immunological and chemotactic factors, proteins of the complement system, histamine, serotonin, arachidonic acid products and cytokines. All these compounds, including cytokines/chemokines, are major contributors to the symptoms of inflammation. Cytokines/chemokines, commonly referred to as “biological response modifiers”, are relatively new compounds for possible use in stimulation of the immune response, and display a number of overlapping abilities to stimulate cells of various lineages and differentiation stages; nonetheless, most of these compounds are potent inflammatory mediators. Mast cell mediators are either contained within secretory granules or can be synthesized de novo and can be released upon activation by either a massive degranulation, or by a selective release of specific molecules. These cells accumulate in the stroma of a variety of inflamed and transformed tissues in response to locally produced chemotactic factors for immune-cells, such as RANTES and MCP-1. Here we describe some connections between mast cells and chemokines.