Nontuberculous mycobacteria pulmonary infection in medical intensive care unit: the incidence, patient characteristics, and clinical significance

The impact of nontuberculous mycobacterial lung disease in critically ill patients: Significance for survival and ventilator use

BACKGROUND

This study investigates the impact of nontuberculous mycobacterial lung disease (NTM-LD) on mortality and mechanical ventilation use in critically ill patients.

METHODS

We enrolled patients with NTM-LD or tuberculosis (TB) in intensive care units (ICU) and analysed their association with 30-day mortality and with mechanical ventilator-free survival (VFS) at 30 days after ICU admission.

RESULTS

A total of 5996 ICU-admitted patients were included, of which 541 (9.0 %) had TB and 173 (2.9 %) had NTM-LD. The overall 30-day mortality was 22.2 %. The patients with NTM-LD had an adjusted hazard ratio (aHR) of 1.49 (95 % CI, 1.06-2.05), and TB patients had an aHR of 2.33 (95 % CI, 1.68-3.24), compared to ICU patients with negative sputum mycobacterial culture by multivariable Cox proportional hazard (PH) regression. The aHR of age<65 years, obesity, idiopathic pulmonary fibrosis, end-stage kidney disease, active cancer and autoimmune disease and diagnosis of respiratory failure were also significantly positively associated with ICU 30-day mortality. In multivariable Cox PH regression for VFS at 30 days in patients requiring invasive mechanical ventilation, NTM-LD was negatively associated with VFS (aHR 0.71, 95 % CI: 0.56-0.92, p = 0.009), while TB showed no significant association. The diagnosis of respiratory failure itself predicted unfavourable outcome for 30-day mortality and a negative impact on VFS at 30 days.

CONCLUSIONS

NTM-LD and TB were not uncommon in ICU and both were correlated with increasing 30-day mortality in ICU patients. NTM-LD was associated with a poorer outcome in terms of VFS at 30 days.

Pulmonary mycobacterial infection is associated with increased mortality in patients with acute respiratory distress syndrome

Although pulmonary mycobacterial infection is associated with acute respiratory distress syndrome (ARDS) in critically ill patients, its clinical implication on patients with ARDS has not been clearly elucidated. The aim of study was to investigate the clinical significance of pulmonary mycobacterial infection in patients with ARDS.Between January 2014 and April 2019, medical records of 229 patients with ARDS who met the Berlin criteria and received invasive mechanical ventilation in medical intensive care unit were reviewed. Clinical characteristics and the rate of mortality between patients with and without pulmonary mycobacterial infection were compared. Factors associated with a 28-day mortality were analyzed statistically.Twenty two (9.6%) patients were infected with pulmonary mycobacteria (18 with tuberculosis and 4 with non-tuberculous mycobacteria). There were no differences in baseline characteristics, the severity of illness scores. Other than a higher rate of renal replacement therapy required in those without pulmonary mycobacterial infection, the use of adjunctive therapy did not differ between the groups. The 28- day mortality rate was significantly higher in patients with pulmonary mycobacterial infection (81.8% vs 58%, P = .019). Pulmonary mycobacterial infection was significantly associated with 28-day mortality (hazard ratio 1.852, 95% confidence interval 1.108-3.095, P = .019).Pulmonary mycobacterial infection was associated with increased 28-day mortality in patients with ARDS.

Exacerbating factors in elderly patients with Mycobacterium avium complex pulmonary disease

No previous studies have examined Mycobacterium avium complex pulmonary disease (MAC-PD) in only elderly patients ⩾75 years old. Here, we investigated the exacerbating factors of MAC-PD in elderly patients and clarified cases that can be followed up without MAC medication. From April 2011 to March 2019, 126 advanced aged patients at our institute were newly diagnosed with MAC-PD, and could be observed based on radiological findings for over a year. Their medical records were retrospectively examined for clinical and radiological findings at the time of diagnosis and 1 year later. To identify the predictors of exacerbation, clinical characteristics of 109 treatment-naïve patients were compared between exacerbated and unchanged groups. Additionally, the unchanged group was followed for one more year. In the current study, positive acid-fast bacilli smears from the sputum test, the presence of cavitary lesions and extensive radiological findings, particularly abnormal shadows in ⩾3 lobes, were predictive of exacerbation among treatment-naïve elderly MAC-PD patients. In the unchanged group, <10% showed exacerbation of radiological findings within the subsequent year. In conclusion, if the sputum smear is negative, no cavitary lesions are present, and abnormal shadows are restricted to ⩽2 lobes, elderly patients with MAC-PD may remain untreated for a few years.

Nontuberculous mycobacterial lung disease epidemiology in Taiwan: A systematic review

Nontuberculous mycobacteria (NTM) are critical emerging global infectious pathogens. Though NTM can be mere colonizers when isolated from human specimens, NTM are also responsible for diverse human infections. NTM-lung disease (NTM-LD) is the most common human disease entity. The present review aims to provide general insight into NTM-LD epidemiology in Taiwan. In reviewing NTM epidemiology in Taiwan, we discovered three distinguishing features. First, NTM disease incidence has increased in Taiwan over the past decade. Second, the distribution of NTM varies geographically in Taiwan. Mycobacterium avium-intracellulare complex (MAC) is the dominant species in northern Taiwan, whereas Mycobacterium abscessus complex and MAC may be equally dominant in southern Taiwan. Third, researchers in Taiwan have published valuable research investigating NTM among special patient populations, including patients in intensive care units, with ventilator dependency, with pulmonary tuberculosis, and who are infected with specific NTM species. The largest obstacle to clarifying NTM epidemiology in Taiwan may be the lack of routine NTM species identification in laboratories. Increased awareness of NTM diseases and acknowledgment that NTM species identification is crucial and guides clinical management are essential steps for facilitating the identification of NTM species in laboratories.

Clinical relevance and diagnosis of nontuberculous mycobacterial pulmonary disease in populations at risk

The lungs are the most common disease site of nontuberculous mycobacteria (NTM). However, the isolation of NTM in a respiratory specimen does not indicate lung disease (LD). Differentiation between NTM colonization and NTM-LD remains challenging. In this brief review, we summarize the clinical impact of NTM-LD on morbidity and mortality in high-risk populations. The diagnosis criteria for NTM-LD-including clinical features, radiological presentations, and microbiological evidence-are also reviewed, according to the latest American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA) guideline and the British Thoracic Society (BTS) guideline. However, the diagnosis of NTM-LD does not necessitate the initiation of anti-NTM treatment. Both environmental, host, and bacterial factors should be considered to identify patients that require NTM-LD treatment.

Host immune response against environmental nontuberculous mycobacteria and the risk populations of nontuberculous mycobacterial lung disease

Nontuberculous mycobacterial lung disease (NTM-LD) prevalence has been increasing over the recent decades. Numerous host factors are associated with NTM-LD development, including susceptible phenotypes such as ciliary defect and lung structural change, pulmonary clearance defect with poor clearance of secretions, and immune suppression. Specifically, regarding the susceptible host phenotypes without clear pathogenesis, a slender body, pectus excavatum, and postmenopausal female status are common. Also, decreased host immunity to NTM, especially T helper 1 cell responses is frequently observed. Even so, the underlying mechanisms remain unclear and relevant large-scale studies are lacking. Infections due to host genetics associated defects are mostly untreatable but rare in Asia, particularly Taiwan. Nevertheless, some risks for NTM-LD are controllable over disease progression. We suggest that clinicians first manage host factors and deal with the controllable characteristics of NTM-LD, followed by optimizing anti-NTM treatment. Further researches focusing on NTM-LD pathogenesis, especially the host-NTM interaction may advance understanding the nature of the disease and develop efficient therapeutic regimens.

NLRP3 inflammasome is attenuated in patients with Mycobacterium avium complex lung disease and correlated with decreased interleukin-1β response and host susceptibility

The incidence of nontuberculous mycobacteria lung disease (NTM-LD) is increasing in patients without human immunodeficiency virus. Mycobacterium avium complex (MAC) is one of the most common pathogenic species. The presence of MAC has a clinical relevance of around 35~42%, indicating the possibility of host susceptibility. Previous studies have shown that interleukin (IL)-1β and IL-1-receptor knock-out mice are susceptible to mycobacterial infections; however, the role of inflammasome-driven interleukin (IL)-1β has not been studied in MAC-LD. We enrolled patients with MAC-LD and healthy controls. Peripheral blood mononuclear cells (PBMCs), monocytes, and monocyte-derived macrophages were stimulated by MAC bacilli. The responses of interleukin(IL)-1β and the expression of inflammasome and toll-like receptors (TLRs) were measured. Single nucleotide polymorphisms (SNPs) were also examined for NLRP3 and TLR2 genes. In the patients with MAC-LD, the IL-1β responses decreased in PBMCs, monocytes, and macrophages assayed by MAC bacilli in comparison to the healthy controls. In addition, the level of caspase-1 after stimulation was lower in the MAC-LD group, although the mRNA level of IL-1β was not significantly lower. In surveying the activation of IL-1β, the MAC-LD group had an attenuated mRNA level of NLRP3 but similar levels of AIM2 and ASC compared with the controls. The SNPs rs3806268 and rs34298354 in NLRP3 for females and rs3804100 in TLR2 for males were associated with MAC-LD. In conclusion, our patients with MAC-LD had attenuated IL-1β production, which may have been due to lower activation of the NLRP3-caspase-1 axis. Two SNPs of NLRP3 and one of TLR2 were correlated with MAC-LD, possibly indicating host susceptibility.

Mono- and poly-functional T cells in nontuberculous mycobacteria lung disease patients: Implications in analyzing risk of disease progression

AT A GLANCE

The diagnosis and progression of nontuberculous mycobacteria lung disease (NTN-LD) are important for clinical judgement but cannot easily be predicted. The immunological response of mono- and poly-functional T cells, a representative of host reactivity to NTM, could be a surrogate biomarker for disease and progression prediction.

BACKGROUND

Mycobacterium avium complex (MAC) and M. abscessus (MAB) induced lung disease (LD) have become a clinical concern. Predicting clinical disease relevance and progression is important, but suitable biomarkers are lacking. The host immune response of mono- and poly-functional T cells might aid in clinical judgement.

METHODS

We enrolled 140 participants, including 42 MAC-LD, 25 MAB-LD, 31 MAC airway colonization (MAC-Co), 15 MAB-Co patients, and 27 healthy controls. Their blood mono- and poly-functional T cells were measured and analyzed after in-vitro stimulation.

RESULTS

Patients with MAC-LD generally had lower total IFN-γ+, total TNF-α+ and triple-positive T cells but higher mono-IL-2+ expression than the controls and MAC-Co group. The MAB-LD group had lower total IL-2 and triple positive cells than the controls and colonization group. Multivariate analysis revealed that body mass index (BMI), mono-IL2+ CD4+ and triple positive-CD8+ cells (PMA stimulation) significantly predicted MAC-LD from the controls. By contrast, male gender and triple positive-CD4+ cells predicted MAC-LD from colonization. On the other hand, the triple positive-CD4+ cells (PMA stimulation) alone or together with the mock/MAB ratio of IL-2+/TNF-α+ CD4 cells could predict MAB-LD in the MAB-Co group or the controls. Among MAC/MAB-LD patients without anti-mycobacterial treatment, MAC-specific mono-IFN-γ+ CD4+ cells and PMA-induced triple positive-CD4+ cells were correlated with progression, with an area under the ROC curve of 0.875.

CONCLUSIONS

The patients with MAC/MAB-LD had attenuated poly-functional T cells. The triple-positive CD4+ cells could be useful in diagnosing disease from colonization. MAC-specific mono-IFN-γ+ CD4+ cells and triple positive-CD4+ might predict radiographic progression, which could be useful in making treatment decisions.

Latent class analysis to define radiological subgroups in pulmonary nontuberculous mycobacterial disease

Background

Nontuberculous mycobacterial (NTM) pulmonary disease has conventionally been classified on the basis of radiology into fibrocavitary and nodular-bronchiectatic disease. Whilst being of great clinical utility, this may not capture the full spectrum of radiological appearances present. The aim of this study was to use latent class analysis (LCA) as an unbiased method of grouping subjects with NTM-pulmonary disease based on their CT features and to compare the clinical characteristics of these groups.

Methods

Individuals with NTM-pulmonary disease were recruited and a contemporaneous CT scan obtained. This was scored using an NTM-specific scoring system. LCA was used to identify groups with common radiological characteristics. The analysis was then repeated in an independent cohort.

Results

Three classes were identified in the initial cohort of 85 subjects. Group 1 was characterised by severe bronchiectasis, cavitation and aspergillomas, Group 2 by relatively minor radiological changes, and Group 3 by predominantly bronchiectasis only. These findings were reproduced in an independent cohort of 62 subjects. Subjects in Group 1 had a lower BMI and serum albumin, higher serum CRP, and a higher mortality.

Conclusions

These findings suggest that NTM-pulmonary may be divided into three radiological subgroups, and that important clinical and survival differences exist between these groups.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0675-8) contains supplementary material, which is available to authorized users.

Microbiological Persistence in Patients With Mycobacterium avium Complex Lung Disease: The Predictors and the Impact on Radiographic Progression

Background

Persistent growth of Mycobacterium avium complex (MAC) in the lungs indicates continuous infection in MAC lung disease (MAC-LD), but its clinical significance has not been investigated. We aimed to evaluate the predictors of persistent culture-positivity for MAC (MAC-PP) and its impact on radiographic deterioration in MAC-LD.

Methods

Patients with MAC-LD at multiple medical centers from 2011 to 2016 were enrolled retrospectively. Microbiological persistence of MAC-LD was defined as MAC-PP exceeding 1 year, in contrast with the negative-conversion group. The outcome was radiographic progression, namely, increased number of involved lung areas or cavitary formation.

Results

Among 126 patients with MAC-LD, 75 (60%) were in the MAC-PP group; these patients had a higher proportion of radiographic progression (54%) than patients in the negative-conversion group (odds ratio [OR], 3.318; 95% confidence interval, 1.146-9.612). Independent predictors of MAC-PP were low body mass index (BMI), radiographic nodular-bronchiectatic (NB) pattern, and increase in the highest grade of acid-fast bacilli smear (AFS). Patients with BMI <21 kg/m2, NB pattern, and positive AFS had an OR of 17.7 for MAC-PP, and those with ≥2 of the factors had a 4.5-fold increased OR for MAC-PP relative to the comparison group. Other than MAC-PP, the highest AFS grade and no anti-MAC treatment were correlated with radiographic progression.

Conclusion

Microbiological persistence in patients with MAC-LD is not uncommon and leads to an increased risk of radiographic progression. The predictors of MAC-PP are low BMI, NB pattern, and high AFS grade; if these risk factors are present, anti-MAC treatment should be seriously considered.

Development and validation of a prognostic scoring model for Mycobacterium avium complex lung disease: an observational cohort study

Background

Patients with Mycobacterium avium complex (MAC) lung disease (LD) have a heterogeneous prognosis. This study aimed to develop and validate a prognostic scoring model for these patients using independent risk factors for survival.

Methods

We retrospectively analyzed the data of patients with MAC-LD from two hospitals (cohort 1, n = 368; cohort 2, n = 118). Cohort 1 was evaluated using a multivariate Cox proportional hazards model to identify independent risk factors for overall survival (OS). A prognostic scoring model composed of these factors was developed, and cohort 1 was stratified into three groups according to risk using the log-rank test. Finally, the prognostic scoring model was validated using the data of cohort 2.

Results

Seven independent risk factors for OS were selected from cohort 1, including the male sex, age ≥ 70 years, the presence of a malignancy, body mass index <18.5 kg/m², lymphocyte count <1000 cells/μL, serum albumin levels <3.5 g/dL, and fibrocavitary disease. The areas under the receiver operating characteristic curves for the prognostic scoring model were 0.84 [95% confidence interval (CI), 0.80 − 0.89] for cohort 1 and 0.84 (95% CI, 0.75 − 0.92) for cohort 2. The 5-year OS rates of patients stratified into low-risk, intermediate-risk, and high-risk groups were 97.6, 76.6, and 30.8%, respectively (P < 0.001), in cohort 1, and 97.2, 82.3, and 45.4%, respectively (P < 0.001), in cohort 2.

Conclusions

This study is the first to develop and validate a prognostic scoring model for patients with MAC-LD. This model may prove useful in clinical settings and practical in estimating the prognosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2544-0) contains supplementary material, which is available to authorized users.

The trend and the disease prediction of vascular endothelial growth factor and placenta growth factor in nontuberculous mycobacterial lung disease

Nontuberculous mycobacteria (NTM)-lung disease (LD) is an increasing health problem worldwide. The diagnosis of this disease remains difficult, however the application of placenta growth factor (PlGF) and vascular endothelial growth factor (VEGF) has not yet been studied. We screened patients with Mycobacterium avium complex or M. abscessus isolated from sputum, and enrolled 32 patients with NTM-LD and 93 with NTM pulmonary colonization. The NTM-LD group had a lower body mass index, higher proportion of bronchiectasis, more respiratory symptoms and pulmonary lesions, and higher titers of sputum acid-fast stain than the NTM pulmonary colonization group. The plasma level of PlGF was lower in the NTM-LD group than in the NTM colonization group, whereas the level of VEGF was higher in the NTM-LD group. In multivariable logistic regression analysis excluding NTM cultures, the predictive model for NTM-LD included sputum AFS titer, a nodular-bronchiectasis radiographic pattern, plasma VEGF/PlGF ratio, and chest radiographic score (VEGF/P1GF ratio became not significant as a factor in multivariable generalized linear model). The four-factor predictive index had good positive likelihood ratio and negative likelihood ratio for predicting NTM-LD in the patients with NTM in their sputum.

Acquisition of Mycobacterium abscessus among ventilator-dependent patients in Taiwan chronic respiratory care facilities

AIM

To investigate the acquisition of Mycobacterium abscessus among ventilator-dependent patients.

MATERIALS & METHODS

We prospectively recruited ventilator-dependent patients in five respiratory care wards (RCWs). Respiratory specimens were cultured for mycobacteria on day 1 (D1), 3 months (M3) and 6 months (M6) after enrollment.

RESULTS

72 patients had cultures taken at all three time points. The proportion of patients with a culture positive for M. abscessus increased from 15.3% (11/72) on D1 to 30.6% (22/72) at M3 and 38.9% (28/72) at M6. Two M. abscessus subspecies abscessus isolates obtained from different patients had identical randomly amplified polymorphic DNA patterns. Being in RCW D and advanced age were significantly associated with initial cultures positivity.

CONCLUSION

Our study reveals that acquisition of M. abscessus was common among ventilator-dependent patients.

Health-related quality of life, comorbidities and mortality in pulmonary nontuberculous mycobacterial infections: A systematic review

Nontuberculous mycobacterial (NTM) infections are increasing in disease frequency worldwide. This systematic review examines health-related quality of life (HRQOL), comorbidities and mortality associated with pulmonary NTM disease. We searched MEDLINE, EMBASE, CINAHL, Scopus Life Sciences, conference proceedings and Google (earliest date available to February 2015) for primary studies. Eligible studies compared populations with and without pulmonary NTM disease in high-income jurisdictions. We excluded studies on HIV/AIDS. All languages were accepted. Two reviewers followed MOOSE and PRISMA reporting guidelines and independently appraised quality using STROBE. All studies were summarized qualitatively regardless of quality. Of 3193 citations screened, we included 17 studies mostly from Taiwan (n = 5) and the USA (n = 4). Two studies assessed HRQOL; one assessed comorbidities, 11 assessed mortality, and three assessed multiple outcomes. Populations with pulmonary NTM reported significantly worse or similar HRQOL than the general population, depending on the instruments used. Some suggested greater prevalence of having bronchiectasis (n = 2) and greater risk of developing pulmonary tuberculosis (n = 1). Most (n = 7) suggested no difference in mortality, although only one was age-matched and gender-matched to the general population. Four suggested NTM populations had higher mortality-two of which compared with the general population and were deemed of high quality, while two compared with non-NTM patients from hospital. High clinical heterogeneity in study design may explain discordant results. Bias assessments and controlling for confounding were carried out poorly. No consistent trends were observed although there is suggestion of an increased health burden from respiratory diseases and increased mortality associated with pulmonary NTM disease.

Prevalence of nontuberculous mycobacteria in patients with bronchiectasis: a meta-analysis

INTRODUCTION

Nontuberculous mycobacteria (NTM) have emerged as critical opportunistic pathogens of lung diseases recently. Patients with preexisting bronchiectasis are susceptible to NTM. Nevertheless, patients with preexisting bronchiectasis are susceptible to NTM but the prevalence of NTM pulmonary infection in different species and geographical areas is still not fully understood.

MATERIAL AND METHODS

The relevant data of the prevalence of NTM in patients with bronchiectasis were retrieved by searching the main databases such as PubMed, MEDLINE, Cochrane Library, and EMBASE. This meta-analysis was performed using Rev. Man 5.1 and Stata 11.0 software. The collected information of NTM prevalence was chosen as the effect size.

RESULTS

The results of the meta-analysis showed that the overall prevalence of NTM was 9.3% in patients with bronchiectasis. The further stratification of subgroup analysis indicated that the combined prevalence of NTM was higher in studies whose "sample size" was more than or equal to 100 (p = 0.002), in studies in which "time of study" was after or equal to 2002 (p < 0.001), in studies in which "participants' geographic location" was Asian (p < 0.001) and in studies whose "method of study" was retrospective (p = 0.002) as well, compared with corresponding groups.

CONCLUSIONS

Our findings suggested that the prevalence NTM infection is high in patients with bronchiectasis. A larger number of definitive randomized trials are still required to assess this research issue.

Diseases caused by nontuberculous mycobacteria in Asia

 The isolation rate of nontuberculous mycobacteria (NTM) species and the prevalence of NTM-associated diseases are on the rise in Asian, as well as in Western countries; however, the species distribution of NTM isolates and the types of diseases caused by NTM species vary from region to region. In this review, we present an update on the epidemiology of NTM in Asia. We demonstrate that the distribution of NTM species varies within Asia and differs from that in North America and Europe. In addition, the clinical manifestations of NTM diseases include respiratory tract infections, disseminated infections, skin and soft tissue infections, lymphadenitis, empyema, ocular infections, CNS infections and genitourinary infections. Finally, the rate of adaptive resistance of anti-NTM antimicrobial agents remains high and may be associated with a poor outcome for patients with NTM diseases.

Nontuberculous mycobacterial infection is associated with increased respiratory failure: a nationwide cohort study

BACKGROUND AND PURPOSE

Population study on relationship between nontuberculous mycobacterial (NTM) infection and respiratory failure (RF) is limited. This study evaluated the RF risk, including acute respiratory failure (ARF), chronic respiratory failure (CRF) and ARF on CRF, in patients with NTM infection in Taiwan.

METHODS

We used the National Health Insurance Research Database of Taiwan to identify 3864 newly diagnosed NTM patients (NTM cohort) from 1999 to 2009, and 15456 non-NTM patients (non-NTM cohort), frequency matched by demographic status for comparison. Incidence and hazard of developing RF were measured by the end of 2010.

RESULTS

The incidence rate of RF was 4.31-fold higher in the NTM cohort than in the non-NTM cohort (44.0 vs.10.2 per 1000 person-years), with an adjusted hazard ratio (HR) of 3.11 (95% CI: 2.73-3.54). The cumulative proportional incidence of RF was 10% higher in the NTM cohort than in the non-NTM cohort (P<0.0001). The RF risk was much greater within 6 months after the diagnosis of NTM infection with a HR of 7.45 (95% CI = 5.50-10.09). Age-specific comparison showed that the younger NTM patients had a higher HR of RF than the elderly NTM patients (HR: 4.42, 95% CI: 3.28-5.96 vs. HR: 2.52, 95% CI: 2.17-2.92). Comorbidity increased the risk of RF in both cohorts, particularly in those with chronic obstructive pulmonary disease.

CONCLUSION

Our study suggests patients with NTM infection are at a high risk of RF. The risk appears much greater soon after patients diagnosed with NTM infection.

An outbreak of Mycobacterium abscessus infection in a Pediatric Intensive Care Unit in Kuwait

BACKGROUND

Mycobacterium abscessus has been associated with respiratory tract infections, localized skin and soft tissue infections and sepsis. However, outbreaks of M. abscessus are rare.

AIM

to report an outbreak of M. abscessus causing respiratory tract infections in a Pediatric Intensive Care Unit (PICU) in Kuwait, its investigation and control measures.

METHODS

Respiratory secretions were obtained from ventilator-dependent patients showing signs of sepsis, including fever, malaise and weight loss. The specimens were cultured on appropriate routine media. After the results of the sample taken from the index case as acid-fast bacilli positive, all patients were screened for M. abscessus carriage. Isolates were identified by INNO-LiPA Mycobacteria v2 line probe assay and DNA sequencing. Molecular fingerprinting DiversiLab strain typing was performed on the isolates. Epidemiologic investigation was conducted during the outbreak.

FINDINGS

the outbreak affected 5 patients, 4 of whom had severe infections including 1 patient with septicemia. Asymptomatic carriage of outbreak strain was found in 1 patient. All environmental samples were negative for M. abscessus but some were positive for M. gordonae and M. fortuitum. The source could not be identified. Stringent infection control measures were put in place, including reemphasizing hand hygiene and closure of the Pediatric Intensive Care Unit to new admissions. A year later, no further case has occurred after the last case.

CONCLUSION

To our knowledge, this is the first report of a hospital-acquired outbreak of respiratory tract infection caused by M. abscessus in a Pediatric Intensive Care Unit. In the absence of definite source identification, reinforcement of standard infection control guidelines was successful in containing the outbreak.

Sero-diagnosis of Mycobacterium avium complex lung disease using serum immunoglobulin A antibody against glycopeptidolipid antigen in Taiwan

Background

Lung disease (LD) due to non-tuberculous mycobacteria is an important clinical concern. Mycobacterium avium complex (MAC) is one of the most common causative agents but the diagnosis of MAC-LD remains challenging. Detection of serum IgA antibody against MAC glycopeptidolipid (GPL) has recently been shown to improve the diagnosis of MAC-LD, but has yet to be validated worldwide.

Methods

This prospective study was conducted in a tertiary referral center in northern Taiwan and enrolled patients with MAC-LD, MAC contamination, other lung diseases, and control subjects. Serum immunoglobulin A (IgA) antibody against MAC-GPL was detected in the participants and its specificity and sensitivity was assessed.

Results

There were 56 patients with MAC-LD, 11 with MAC contamination, 13 M. kansasii-LD, 26 LD due to rapidly-growing mycobacteria (RGM), 48 pulmonary tuberculosis, and 42 household contacts of patients with TB. Patients with MAC-LD were older and 32% of them had an underlying co-morbidity. By logistic regression, serum MAC-GPL IgA level was an independent predictor of MAC-LD among the study subjects and those with culture-positive specimens for MAC. By the receiver operating characteristic curve, serum MAC-GPL IgA had a good power to discriminate MAC-LD from MAC contamination. Under the optimal cut-off value of 0.73 U/mL, its sensitivity and specificity were 60% and 91%, respectively. Among MAC-LD patients, presence of co-morbidity was associated with MAC-GPL <0.73 U/ml in logistic regression analysis.

Conclusions

Measurement of serum anti-MAC-GPL IgA level is useful for the diagnosis of MAC-LD. However, its implement in clinical practice for immuno-compromised hosts needs careful consideration.

Clinical review: tuberculosis on the intensive care unit

Rates of tuberculosis (TB) are increasing in most west European nations. Patients with TB can be admitted to an ICU for a variety of reasons, including respiratory failure, multiorgan failure and decreased consciousness associated with central nervous system disease. TB is a treatable disease but the mortality for patients admitted with TB to an ICU remains high. Management challenges exist in establishing a prompt diagnosis and administering effective treatment on the ICU with potentially poor gastric absorption and high rates of organ dysfunction and drug toxicity. In this review reasons for ICU admission, methods of achieving a confident diagnosis through direct and inferred methods, anti-tuberculosis treatment (including steroid and other adjuvant therapies) and specific management problems with particular relevance to the intensivist are discussed. The role of therapeutic drug monitoring, judicious use of alternative regimes in the context of toxicity or organ dysfunction and when to suspect paradoxical tuberculosis reactions are also covered. Diagnostic and therapeutic algorithms are proposed to guide ICU doctors in the management of this sometimes complicated disease.

Community-based prevalence of undiagnosed mycobacterial diseases in the Afar Region, north-east Ethiopia

BACKGROUND

Information on the community-based prevalence of tuberculosis (TB) in different settings is vital for planning, execution and evaluation of strategies to control the disease.

OBJECTIVE

To assess community-based prevalence of undetected active pulmonary TB (PTB) in pastoralists of the Amibara District.

METHODS

Between March and April 2010, a community-based cross-sectional survey of undiagnosed active PTB was conducted in the pastoralists of the Amibara District of the Afar Region, north-east Ethiopia. The study participants were interviewed for symptoms suggestive of PTB using a structured questionnaire. Sputum samples were collected and processed for smear microscopy and culture. Mycobacterium genus typing was performed using a multiplex polymerase chain reaction (PCR).

RESULTS

Out of 222 individuals who had symptoms suggestive of PTB, 4 (1.8%) were found positive by smear microscopy, while mycobacterial growth was observed on 62 (27.9%) samples. Mycobacterium genus typing was carried out for 42 of these 62 samples; 39 (92.9%) gave a positive signal for the genus Mycobacterium. Of these, 23 (59%) isolates proved to be members of the Mycobacterium tuberculosis (Mtb) complex, while the remaining 16 (41.0%) were found to be members of non-tuberculous Mycobacteria (NTM) species.

CONCLUSION

Sputum culture is highly sensitive, and it is the gold standard for the bacteriological diagnosis of PTB, while smear microscopy is less sensitive to detect acid fast bacilli (AFB) in stained sputum smears. The findings of the present study warrant the strengthening of culture facility services in the study area. The study also provides important preliminary information on the status of NTM infection in the pastoral setting. Nevertheless, further investigations into the species identification of the NTM infections would be useful in the study area.

Prognostic value of American Thoracic Society criteria for non-tuberculous mycobacterial disease: a retrospective analysis of 120 cases with four years of follow-up

BACKGROUND

Non-tuberculous mycobacteria (NTM) cause disease in healthy and immunocompromised patients. The American Thoracic Society (ATS) 2007 diagnostic criteria were devised to distinguish NTM disease from airway colonization. The aim of this study was to evaluate the prognostic value of the ATS criteria.

METHODS

In a 4-y follow-up study that ended on 8 June 2006, we retrospectively analyzed the symptoms, underlying diseases, and mortality of 120 adult non-HIV patients with NTM culture findings obtained between 1990 and 1998. We categorized the patients according to the 2007 ATS NTM case definition into positive and negative groups.

RESULTS

Only 61/120 patients (51%) fulfilled the ATS criteria for NTM disease. As compared to ATS-negative subjects, the ATS-positive group showed lower age, a higher proportion of females, and fewer fatal underlying diseases. Among ATS-negative subjects, 46/59 (78%) did not fulfil the microbiological criteria and 43/59 (73%) did not fulfil the radiological criteria. Mycobacterium avium complex (MAC) comprised 61% of isolations in the ATS-positive and 47% in the ATS-negative group (p = 0.15). No significant difference in median survival time was found between the groups: ATS-positive 7.4 y (95% confidence interval (CI) 0.2-14.6) and ATS-negative 5.3 y (95% CI 3.0-7.6). No significant difference was found in symptoms except fatigue, which was more common in the ATS-positive (56% vs 37%, p = 0.04). Symptoms lasted for less than a year in 48%, which suggests a more rapid disease progression than has previously been reported.

CONCLUSIONS

The fulfillment of ATS criteria was poorly associated with any difference in prognosis, and based on our findings would be a poor prognostic marker.

Nontuberculous mycobacteria in respiratory tract infections, eastern Asia

To characterize the distribution of nontuberculous mycobacteria (NTM) species isolated from pulmonary samples from persons in Asia and their association with pulmonary infections, we reviewed the literature. Mycobacterium avium complex bacteria were most frequently isolated (13%-81%) and were the most common cause of pulmonary NTM disease (43%-81%). Also pathogenic were rapidly growing mycobacteria (M. chelonae, M. fortuitum, M. abscessus). Among all NTM isolated from pulmonary samples, 31% (582/1,744) were considered clinically relevant according to American Thoracic Society diagnostic criteria. Most patients were male (79%) and had a history of tuberculosis (37%). In Asia, high prevalence of rapidly growing mycobacteria and a history of tuberculosis are distinct characteristics of pulmonary NTM disease. This geographic variation is not well reflected in the American Thoracic Society criteria for NTM infections and could be incorporated in future guidelines.

Nontuberculous mycobacteria in respiratory tract infections, eastern Asia

To characterize the distribution of nontuberculous mycobacteria (NTM) species isolated from pulmonary samples from persons in Asia and their association with pulmonary infections, we reviewed the literature. Mycobacterium avium complex bacteria were most frequently isolated (13%-81%) and were the most common cause of pulmonary NTM disease (43%-81%). Also pathogenic were rapidly growing mycobacteria (M. chelonae, M. fortuitum, M. abscessus). Among all NTM isolated from pulmonary samples, 31% (582/1,744) were considered clinically relevant according to American Thoracic Society diagnostic criteria. Most patients were male (79%) and had a history of tuberculosis (37%). In Asia, high prevalence of rapidly growing mycobacteria and a history of tuberculosis are distinct characteristics of pulmonary NTM disease. This geographic variation is not well reflected in the American Thoracic Society criteria for NTM infections and could be incorporated in future guidelines.

In-hospital outcome of patients with culture-confirmed tuberculous pleurisy: clinical impact of pulmonary involvement

BACKGROUND

Outcomes for hospitalized patients with tuberculous pleurisy (TP) have rarely been reported, and whether or not pulmonary involvement affects outcomes is uncertain. This study aimed to analyze the in-hospital mortality rate of culture-confirmed TP with an emphasis on the clinical impact of pulmonary involvement.

METHODS

Patients who were hospitalized for pleural effusion (PE) of unconfirmed diagnosis and finally diagnosed as TP were identified. We classified them according to the disease extent: isolated pleurisy (isolated pleurisy group) and pleurisy with pulmonary involvement (pleuro-pulmonary group).

RESULTS

Among the 205 patients hospitalized before the diagnosis was established, 51 (24.9%) belonged to the isolated pleurisy group. Compared to the pleuro-pulmonary group, patients in the isolated pleurisy group were younger, had fewer underlying co-morbidities, and presented more frequently with fever and chest pain. Fewer patients in the isolated pleurisy group had hypoalbuminemia (< 3.5 g/dL) and anemia. The two groups were similar with regards to PE analysis, resistance pattern, and timing of anti-tuberculous treatment. Patients who had a typical pathology of TP on pleural biopsy received anti-tuberculous treatment earlier than those who did not, and were all alive at discharge. The isolated pleurisy group had a lower in-hospital mortality rate, a shorter length of hospital stay and better short-term survival. In addition, the presence of underlying comorbidities and not receiving anti-tuberculous treatment were associated with a higher in-hospital mortality rate.

CONCLUSION

In culture-confirmed tuberculous pleurisy, those with pulmonary involvement were associated with a higher in-hospital mortality rate. A typical pathology for TP on pleura biopsy was associated with a better outcome.

Identification of nontuberculous mycobacterial infection by IS6110 and hsp65 gene analysis on lung tissues

The clinical, histologic, and radiographic presentations of nontuberculous mycobacterial (NTM) lung disease are usually indistinguishable from those of reactivated pulmonary tuberculosis (TB), so it remains a great challenge for the clinician to make treatment decisions for patients with old TB and a positive culture result for NTM. This study investigated whether the mycobacterial specific heat shock protein 65 (hsp65) and Mycobacterium tuberculosis (MTB)-specific IS6110 gene would present in pulmonary lesions of patients with NTM pulmonary infection. Formalin-fixed and paraffin-embedded (FFPE) tissue blocks of 24 patients with NTM infections treated at the hospital from 1998 to 2008 were included. Mycobacterial hsp65 gene was amplified in 20 of the 24 patients, and the species identified by sequencing was consistent with corresponding culture results in 12 of these patients. MTB-specific IS6110 gene was detected in 3 of the 7 patients who had old TB and a subsequent diagnosis of fibrocavitary NTM lung disease. Polymerase chain reaction (PCR) analysis of hsp65 gene also confirmed the presence of MTB genes in 2 of these 3 patients. Our results indicate that PCR amplification and sequencing of the mycobacterial hsp65 gene is a sensitive assay for identification of NTM species in FFPE materials. However, consistent results of PCR analysis, microbiology study, histologic manifestations, radiology, and clinical presentation are important for correct diagnosis of NTM pulmonary infection. The presence of MTB gene in patients with fibrocavitary NTM lung lesions poses a clinical dilemma for deciding concurrent treatment TB and NTM infection.

Predicting results of mycobacterial culture on sputum smear reversion after anti-tuberculous treatment: a case control study

Background

Little is currently known regarding sputum smear reversion (acid-fast smear becomes positive again after negative conversion) during anti-tuberculous treatment. This study aimed to evaluate its occurrence in patients with pulmonary tuberculosis (TB) and identify factors predicting results of mycobacterial culture for smear-reversion of sputum samples.

Methods

The retrospective review was performed in a tertiary referral center and a local teaching hospital in Taiwan. From 2000 to 2007, patients with smear-positive culture-confirmed pulmonary TB experiencing smear reversion after 14 days of anti-tuberculous treatment were identified.

Results

The 739 patients with smear-positive pulmonary TB had 74 (10%) episodes of sputum smear reversion that grew Mycobacterium tuberculosis in 22 (30%) (Mtb group). The remaining 52 episodes of culture-negative sputum samples were classified as the non-Mtb group. The anti-tuberculous regimen was modified after confirming smear reversion in 15 (20%). Fourteen episodes in the Mtb group and 15 in the non-Mtb group occurred during hospitalization. All were admitted to the negative-pressure rooms at the time of smear reversion. Statistical analysis showed that any TB drug resistance, smear reversion within the first two months of treatment or before culture conversion, and the absence of radiographic improvement before smear reversion were associated with the Mtb group. None of the smear reversion was due to viable M. tuberculosis if none of the four factors were present.

Conclusions

Sputum smear reversion develops in 10% of patients with smear-positive pulmonary TB, with 30% due to viable M. tuberculosis bacilli. Isolation and regimen modification may not be necessary for all drug-susceptible patients who already have radiographic improvement and develop smear reversion after two months of treatment or after sputum culture conversion.