Environmental risk factors for infection with Mycobacterium avium complex

Supporting Patients with Nontuberculous Mycobacterial Pulmonary Disease: Ensuring Best Practice in UK Healthcare Settings

Nontuberculous mycobacterial pulmonary disease (NTM-PD) results from opportunistic lung infections by mycobacteria other than Mycobacterium tuberculosis or Mycobacterium leprae species. Similar to many other countries, the incidence of NTM-PD in the United Kingdom (UK) is on the rise for reasons that are yet to be determined. Despite guidelines established by the American Thoracic Society (ATS), the Infectious Diseases Society of America, and the British Thoracic Society, NTM-PD diagnosis and management remain a significant clinical challenge. In this review article, we comprehensively discuss key challenges in NTM-PD diagnosis and management, focusing on the UK healthcare setting. We also propose countermeasures to overcome these challenges and improve the detection and treatment of patients with NTM-PD.

Prominent transcriptomic changes in Mycobacterium intracellulare under acidic and oxidative stress

BACKGROUND

Mycobacterium avium complex (MAC), including Mycobacterium intracellulare is a member of slow-growing mycobacteria and contributes to a substantial proportion of nontuberculous mycobacterial lung disease in humans affecting immunocompromised and elderly populations. Adaptation of pathogens in hostile environments is crucial in establishing infection and persistence within the host. However, the sophisticated cellular and molecular mechanisms of stress response in M. intracellulare still need to be fully explored. We aimed to elucidate the transcriptional response of M. intracellulare under acidic and oxidative stress conditions.

RESULTS

At the transcriptome level, 80 genes were shown [FC] ≥ 2.0 and p < 0.05 under oxidative stress with 10 mM hydrogen peroxide. Specifically, 77 genes were upregulated, while 3 genes were downregulated. In functional analysis, oxidative stress conditions activate DNA replication, nucleotide excision repair, mismatch repair, homologous recombination, and tuberculosis pathways. Additionally, our results demonstrate that DNA replication and repair system genes, such as dnaB, dinG, urvB, uvrD2, and recA, are indispensable for resistance to oxidative stress. On the contrary, 878 genes were shown [FC] ≥ 2.0 and p < 0.05 under acidic stress with pH 4.5. Among these genes, 339 were upregulated, while 539 were downregulated. Functional analysis highlighted nitrogen and sulfur metabolism pathways as the primary responses to acidic stress. Our findings provide evidence of the critical role played by nitrogen and sulfur metabolism genes in the response to acidic stress, including narGHIJ, nirBD, narU, narK3, cysND, cysC, cysH, ferredoxin 1 and 2, and formate dehydrogenase.

CONCLUSION

Our results suggest the activation of several pathways potentially critical for the survival of M. intracellulare under a hostile microenvironment within the host. This study indicates the importance of stress responses in M. intracellulare infection and identifies promising therapeutic targets.

A case report: Infection-related glomerulonephritis and mantle cell lymphoma due to mycobacterium avium complex infection

RATIONALE

Mycobacterium avium complex (MAC) infection is common in lung, liver and skin. However, MAC presenting with peritonitis is uncommon and is particularly rare in immunocompetent patients. We report a case of infection-associated glomerulonephritis and mantle cell lymphoma caused by peritonitis due to MAC.

PATIENT CONCERNS

We report a case of a 73-year-old elderly man with fever and abdominal pain for 2 days and gradually developed anuria, ascites, and abdominal lymphadenopathy.

DIAGNOSES

The initial diagnosis was peritonitis and acute renal failure. There was no significant relief of symptoms after empirical anti-infective therapy and hemodialysis. infection-associated glomerulonephritis, mantle cell lymphoma, and peritonitis due to MAC were diagnosed by renal biopsy, abdominal lymph node biopsy, and metagenomics next-generation sequencing.

INTERVENTIONS

The patient received empirical antibiotic therapy, hemodialysis, and anti-MAC therapy.

OUTCOMES

Unfortunately, the patient eventually died of septic shock after the 21st day of admissiom.

LESSONS

Early diagnosis of MAC infection is essential. When the cause of fever is unknown, metagenomics next-generation sequencing can be considered.

Global Epidemiology of Nontuberculous Mycobacterial Pulmonary Disease: A Review

Nontuberculous mycobacterial (NTM) isolation and pulmonary disease (NTM-PD) have continued to increase in most regions of the world, driven mainly by Mycobacterium avium. Single-center studies also support increasing trends as well as a persistent burden of undiagnosed NTM among persons suspected of having tuberculosis (TB), in countries with moderate-to-high TB prevalence. Cumulative exposure to water and soil presents an increased risk to susceptible hosts, and trace metals in water supply are recently recognized risk factors. Establishing standard case definitions for subnational and national surveillance systems with mandatory notification of NTM-PD are needed to allow comparisons within and across countries and regions.

Mycobacteria in Organ Transplant Recipients

This review describes the epidemiology and risk factors of tuberculosis (TB) in solid organ transplant recipients. We discuss the pre-transplant screening for risk of TB and management of latent TB in this population. We also discuss the challenges of management of TB and other difficult to treat mycobacteria such as Mycobacterium abscessus and Mycobacterium avium complex. The drugs for the management of these infections include rifamycins which have significant drug interactions with immunosuppressants and must be monitored closely.

Environmental risk of nontuberculous mycobacterial infection: Strategies for advancing methodology

The National Institute of Allergy and Infectious Diseases organized a symposium in June 2022, to facilitate discussion of the environmental risks for nontuberculous mycobacteria exposure and disease. The expert researchers presented recent studies and identified numerous research gaps. This report summarizes the discussion and identifies six major areas of future research related to culture-based and culture independent laboratory methods, alternate culture media and culturing conditions, frameworks for standardized laboratory methods, improved environmental sampling strategies, validation of exposure measures, and availability of high-quality spatiotemporal data.

Nontuberculous mycobacterial infection and environmental molybdenum in persons with cystic fibrosis: a case-control study in Colorado

RATIONALE

Nontuberculous mycobacteria (NTM) are ubiquitous environmental bacteria that may cause chronic lung disease and are one of the most difficult-to-treat infections among persons with cystic fibrosis (pwCF). Environmental factors likely contribute to increased NTM densities, with higher potential for exposure and infection.

OBJECTIVE

To identify water-quality constituents that influence odds of NTM infection among pwCF in Colorado.

METHODS

We conducted a population-based nested case-control study using patient data from the Colorado CF Center NTM database. We associated data from pwCF and water-quality data extracted from the Water Quality Portal to estimate odds of NTM infection. Using Bayesian generalized linear models with binomial-distributed discrete responses, we modeled three separate outcomes; any NTM infection, infections due to Mycobacterium avium complex species, and infections due to M. abscessus group species.

RESULTS

We observed a consistent association with molybdenum in the source water and M. abscessus group species infection among pwCF in all models. For every 1-unit increase in the log concentration of molybdenum in surface water, the odds of infection for those with M. abscessus group species compared to those who were NTM culture-negative increased by 79%. The odds of M. abscessus group infection varied by county; the counties with the highest probability of infection are located along the major rivers.

CONCLUSIONS

We have identified molybdenum in the source water as the most predictive factor of M. abscessus group infection among pwCF in Colorado. This finding will help inform patients at risk for NTM of their relative risks in residing within specific regions.

Pulmonary nontuberculous mycobacterial infections and environmental factors: A review of the literature

BACKGROUND

Pulmonary nontuberculous mycobacterial (pNTM) infection is mainly acquired through the inhalation of bioaerosols. Nevertheless, behavioural restrictions are rarely given by clinicians to susceptible populations, in part because the available guidelines for pNTM management emphasize more diagnosis and treatment than prevention. Aim of this review is to clarify if pNTM prevention should routinely include recommendations about risk reducing behaviors.

METHODS

We used PubMed as biomedical database. We limited our search to the publication period 2000 to 2020 with selected keyword combinations including "nontuberculous mycobacteria", "water", "soil", and "exposure". Titles and abstract of selected articles were systematically screened. Articles were included in the analysis if they were published under free access through the digital library of the University of Brescia (Italy), and provided full text either in English, French, German or Italian. Articles were excluded if the topic was beyond the aim of our study. Finally, we selected 20 articles.

RESULTS

Studies disagree in identifying the type of aerosol posing the highest risk for the development of pNTM infection. In the retrieved publications the colonization of household niches has been associated with a higher risk of pNTM disease, such as in the exposure to shower aerosols. Considering the non-household settings, the exposure to aerosols in indoor swimming and the higher soil exposure (>2 h/week) seem to correlate with a higher risk to develop pNTM disease. According to our findings, randomized behavioural intervention studies are missing.

CONCLUSIONS

Stringent scientific evidence is missing to formulate recommendations on behavioural risk reduction for pNTM.

Tuberculosis prevalence in animals and humans in the Republic of Kazakhstan

BACKGROUND AND AIM

Tuberculosis is an infectious disease that affects humans and animals. This study aimed to review the influence of economic and organizational, veterinary, and sanitary measures on the epizootic situation of animal tuberculosis and the epidemiological situation of human tuberculosis in the Republic of Kazakhstan.

MATERIALS AND METHODS

The epizootic situation of cattle tuberculosis in Kazakhstan was studied based on the annual statistics of allergy testing of animals with tuberculosis by the Committee for Veterinary Control and Supervision of the Ministry of Agriculture of the Republic of Kazakhstan, according to the results of allergic, clinical, and pathological studies, including laboratory studies of biomaterials from animals that reacted to tuberculin. Tuberculinization of cattle in the country is performed twice in the spring and autumn using tuberculin purified protein derivative for mammals. In addition, mass diagnosis of human tuberculosis is conducted by radiology.

RESULTS

The authors assessed the epizootic situation of tuberculosis in cattle in Kazakhstan from 1991 to 2019. The analysis results showed that at the beginning, the epizootic situation in cattle tuberculosis was challenging. However, since 2001, there has been a noticeable decrease in tuberculosis in animals in Kazakhstan, which has had a favorable effect on the epidemic situation of human tuberculosis.

CONCLUSION

According to the analysis results, the measures used in the Republic of Kazakhstan to prevent tuberculosis improved the well-being of livestock farms. The proper conduct by qualified veterinary specialists on allergy testing of animals and differential diagnosis of nonspecific tuberculin reactions allows establishing an accurate epizootic picture of tuberculosis. Furthermore, strict adherence to instructions on the diagnosis and prevention of tuberculosis, implementation of developed veterinary, sanitary, and organization, and economic measures can improve the epizootic picture of tuberculosis, reducing the risk of human tuberculosis.

Mycobacterium avium infection associated with sterile polyarthritis in a dog

A 1-year-old male neutered Portuguese Podengo dog was presented for lameness, inappetence, pyrexia, diarrhoea and abdominal moderate to severe lymphadenomegaly. Cytology of synovial fluid revealed neutrophilic inflammation in multiple joints suggestive of immune-mediated polyarthritis. Cytology of fine-needle-aspiration material obtained from lymph nodes revealed macrophages with intracytoplasmic, rod-like Ziehl-Neelsen positive staining structures, indicative of mycobacteria. Four-month treatment with enrofloxacin, rifampicin and clarithromycin resulted in clinical improvement and resolution of polyarthritis as evidenced on repeat synoviocentesis, but diarrhoea recurred, Ziehl-Neelsen positive organisms were again found on lymph node cytology and analysis of the 16S rRNA-gene using the Basic Local Alignment Search Tool facility resulted in a match to Mycobacterium avium with 100% sequence identity. Treatment was adjusted to include pradofloxacin, doxycycline, rifampicin and ethambutol and 3 months later the dog is clinically normal. Based on the literature search, this is the first time canine Mycobacterium avium infection associated with immune-mediated polyarthritis is reported. Based on scoping searches, this is the first report of canine Mycobacterium avium infection associated with immune-mediated polyarthritis.

Environmental risk factors associated with pulmonary isolation of nontuberculous mycobacteria, a population-based study in the southeastern United States

The prevalence of pulmonary nontuberculous mycobacteria (NTM) disease is increasing in the United States. Associations were evaluated among residents of central North Carolina between pulmonary isolation of NTM and environmental risk factors including: surface water, drinking water source, urbanicity, and exposures to soils favorable to NTM growth. Reports of pulmonary NTM isolation from patients residing in three counties in central North Carolina during 2006-2010 were collected from clinical laboratories and from the State Laboratory of Public Health. This analysis was restricted to patients residing in single family homes with a valid residential street address and conducted at the census block level (n = 13,495 blocks). Negative binomial regression models with thin-plate spline smoothing function of geographic coordinates were applied to assess effects of census block-level environmental characteristics on pulmonary NTM isolation count. Patients (n = 507) resided in 473 (3.4%) blocks within the study area. Blocks with >20% hydric soils had 26.8% (95% confidence interval (CI): 1.8%, 58.0%), p = 0.03, higher adjusted mean patient counts compared to blocks with ≤20% hydric soil, while blocks with >50% acidic soil had 24.8% (-2.4%, 59.6%), p = 0.08 greater mean patient count compared to blocks with ≤50% acidic soil. Isolation rates varied by county after adjusting for covariates. The effects of using disinfected public water supplies vs. private wells, and of various measures of urbanicity were not significantly associated with NTM. Our results suggest that proximity to certain soil types (hydric and acidic) could be a risk factor for pulmonary NTM isolation in central North Carolina.

Methods for Detecting Mycobacterial Mixed Strain Infections-A Systematic Review

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

Nano-antimicrobials: A New Paradigm for Combating Mycobacterial Resistance

BACKGROUND

Mycobacterium group contains several pathogenic bacteria including M. tuberculosis where the emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) is alarming for human and animal health around the world. The condition has further aggravated due to the speed of discovery of the newer drugs has been outpaced by the rate of resistance developed in microorganisms, thus requiring alternative combat strategies. For this purpose, nano-antimicrobials have emerged as a potential option.

OBJECTIVE

The current review is focused on providing a detailed account of nanocarriers like liposome, micelles, dendrimers, solid lipid NPs, niosomes, polymeric nanoparticles, nano-suspensions, nano-emulsion, mesoporous silica and alginate-based drug delivery systems along with the recent updates on developments regarding nanoparticle-based therapeutics, vaccines and diagnostic methods developed or under pipeline with their potential benefits and limitations to combat mycobacterial diseases for their successful eradication from the world in future.

RESULTS

Distinct morphology and the underlying mechanism of pathogenesis and resistance development in this group of organisms urge improved and novel methods for the early and efficient diagnosis, treatment and vaccination to eradicate the disease. Recent developments in nanotechnology have the potential to meet both the aspects: nano-materials are proven components of several efficient targeted drug delivery systems and the typical physicochemical properties of several nano-formulations have shown to possess distinct bacteriocidal properties. Along with the therapeutic aspects, nano-vaccines and theranostic applications of nano-formulations have grown in popularity in recent times as an effective alternative means to combat different microbial superbugs.

CONCLUSION

Nanomedicine holds a bright prospect to perform a key role in global tuberculosis elimination program.

Non-tuberculous mycobacterial pulmonary disease

Nontuberculous mycobacterial pulmonary disease (NTM-PD) is a challenging infection which is becoming increasingly prevalent, particularly in the elderly, for reasons which are unknown. While underlying lung disease is a well-established risk factor for NTM-PD, it may also occur in apparently healthy individuals. No single common genetic or immunological defect has been identified in this group, and it is likely that multiple pathways contribute towards host susceptibility to NTM-PD which further interact with environmental and microbiological factors leading to the development of disease.The diagnosis of NTM-PD relies on the integration of clinical, radiological and microbiological results. The clinical course of NTM-PD is heterogeneous, with some patients remaining stable without the need for treatment and others developing refractory disease associated with considerable mortality and morbidity. Treatment regimens are based on the identity of the isolated species, drug sensitivity testing (for some agents) and the severity of disease. Multiple antibiotics are typically required for prolonged periods of time and treatment is frequently poorly tolerated. Surgery may be beneficial in selected cases. In some circumstances cure may not be attainable and there is a pressing need for better regimens to treat refractory and drug-resistant NTM-PD.This review summarises current knowledge on the epidemiology, aetiology and diagnosis of NTM-PD and discusses the treatment of two of the most clinically significant species, the M. avium and M. abscessus complexes, with a focus on refractory disease and novel therapies.

Unusual presentation of canine Mycobacterium avium infection

This short communication describes the clinical and morphological findings, diagnosis and treatment of a case of Mycobacterium avium infection in a golden retriever that presented with a progressive nasal swelling and lymphadenopathy. Although well documented in cats, where cutaneous lesions are frequently recognised, canine M avium infection is less commonly reported, and cutaneous lesions are rare. To the authors' knowledge this is the first documented case of canine M avium infection that presented with a cutaneous lesion but no systemic clinical signs. It occurred in a dog with no previously reported breed predisposition and highlights that in cases of cutaneous histiocytic infiltrate in dogs mycobacterial infection should remain a differential diagnosis, even in the absence of suggestive organisms on histopathological examination.

High mortality in peritonitis due to Mycobacterium avium complex: retrospective study and systematic literature review

BACKGROUND

Mycobacterium avium complex (MAC) infection is often disseminated and mainly involves lymph nodes, spleen, liver or bone marrow. Peritonitis due to MAC infection (PMAC) is a very uncommon manifestation.

METHODS

In this report, after describing the case of the only PMAC infection in our 10-year retrospective study, which occurred in an AIDS patient who was non-adherent to highly active antiretroviral therapy (HAART), we performed a systematic literature review of documented bacteriological PMAC.

RESULTS

Including our patient, 51 cases of PMAC have been reported. Patients were most often male (sex ratio 2.14), with a median age of 41 years (2.8-72) and an immunodeficiency in all cases, most often AIDS (57%), cirrhosis (20%) and continuous ambulatory peritoneal dialysis (CAPD) (18%). Ascites was more often chylous (54%) than exudative (46%) and, in this case, lymphocytic (60%), with an inconstantly positive acid-fast bacilli smear (54%). Non-disseminated PMAC patients were more likely to have peritoneal dialysis (39% versus 6.5%, p < .01) or cancer with immunosuppressive therapy (39% versus 0%, p < .0001), while AIDS was the leading underlying disease in disseminated-PMAC patients (83% versus 11%, p < .001). Mortality was high (50%), with no difference between disseminated and non-disseminated PMAC.

CONCLUSIONS

This report highlights the need to be aware of an atypical presentation of PMAC infection, which is associated with a high rate of mortality even for non-disseminated infection.

Detection of Pathogenic and Non-pathogenic Bacteria in Drinking Water and Associated Biofilms on the Crow Reservation, Montana, USA

Private residences in rural areas with water systems that are not adequately regulated, monitored, and updated could have drinking water that poses a health risk. To investigate water quality on the Crow Reservation in Montana, water and biofilm samples were collected from 57 public buildings and private residences served by either treated municipal or individual groundwater well systems. Bacteriological quality was assessed including detection of fecal coliform bacteria and heterotrophic plate count (HPC) as well as three potentially pathogenic bacterial genera, Mycobacterium, Legionella, and Helicobacter. All three target genera were detected in drinking water systems on the Crow Reservation. Species detected included the opportunistic and frank pathogens Mycobacterium avium, Mycobacterium gordonae, Mycobacterium flavescens, Legionella pneumophila, and Helicobacter pylori. Additionally, there was an association between HPC bacteria and the presence of Mycobacterium and Legionella but not the presence of Helicobacter. This research has shown that groundwater and municipal drinking water systems on the Crow Reservation can harbor potential bacterial pathogens.

Isolation of nontuberculous mycobacteria from soil using Middlebrook 7H10 agar with increased malachite green concentration

Environmental exposure is considered to be responsible for nontuberculous mycobacterial infections in humans. To facilitate the isolation of mycobacteria from soil, Middlebrook 7H10 agar was optimized as an enhanced selective medium by increasing the concentration of malachite green. A series of modified Middlebrook 7H10 agar media with malachite green concentrations ranging from 2.5 to 2500 mg/L was evaluated using 20 soil samples decontaminated with 3% sodium dodecyl sulfate plus 2% NaOH for 30 min. Among these modified Middlebrook 7H10 media, the medium with malachite green at a concentration of 250 mg/L, i.e., at the same concentration as in Löwenstein–Jensen medium, was the most effective in terms of the number of plates with mycobacterial growth. This medium was further evaluated with 116 soil samples. The results showed that 87.1% (101/116) of the samples produced mycobacterial growth, and 15 samples (12.9%) produced no mycobacterial growth. Of the plates inoculated with the soil samples, each in duplicate, 5.2% (12/232) showed late contamination. In total, 19 mycobacterial species were isolated, including seven (36.8%) rapidly growing mycobacteria and 12 (63.2%) slowly growing mycobacteria. Our results demonstrate that the modified Middlebrook 7H10 agar with 250 mg/L malachite green is useful for the primary isolation of nontuberculous mycobacteria from soil.

Diagnostics of tuberculosis and differentiation of nonspecific tuberculin reactions in animals

Tuberculosis is a serious disease of humans and animals, caused by bacteria of the Mycobacterium genus. This leads to complications in the life of the sick person, and subsequently to death. The cattle, who have been diagnosed with this bacterium, are usually sent to the slaughter, with the result that their livestock is reduced. Mycobacteriosis is also a disease, after determining which cattle are most often sent to slaughter. Such a reduction in livestock numbers has a negative effect on the economy. Of the 300 samples from the animals, 25 cultures of atypical bacteria responding to tuberculin were isolated. A series of tests – intravenous tuberculin test, ophthalmic test, palpebral test, “ZhAT” test, showed that most of the tuberculosis changes in cattle were found in regional lymph nodes more often than in internal organs. In healthy for tuberculosis cows, at the age of 4–9 years, seasonal nonspecific sensitivity to tuberculin is observed. Implementation of the developed express method of glutaraldehyde test on farms in healthy tuberculosis will speed up the diagnosis of tuberculosis and mycobacteriosis in animals that reacted to tuberculin and will exclude short-term nonspecific sensitization of their organism to tuberculin. The introduction of this methodology can be used to diagnose and clearly differentiate the diagnoses of “tuberculosis” and “mycobacteriosis” in cattle. This will cure part of the livestock and reduce the amount of slaughter.

Nontuberculous mycobacteria in Denmark, incidence and clinical importance during the last quarter-century

Disease caused by nontuberculous mycobacteria (NTM) is reported to increase due to an ageing population and a rise in the proportion of immunosuppressed patients. We did a retrospective cohort study of NTM-disease in the Danish population through a quarter-century to determine the disease burden and trends in annual incidence rates. 524,119 clinical specimens were cultured for mycobacteria from 1991 through 2015 at the International Reference Laboratory of Mycobacteriology in Denmark. Among these, 8,227 NTM strains were identified from 3,462 patients and distributed according to microbiological disease criteria. We observed no increase in NTM disease incidence or proportion of patients with positive NTM cultures during the study period (Quasi-Poisson regression, p = 0.275 and 0.352 respectively). Annual incidence rates were 1.20/10⁵ for definite NTM disease, 0.49/10⁵ for possible NTM disease and 0.88/10⁵ for NTM colonization. The incidence rate of NTM disease was highest in children aged 0-4 years (5.36/10⁵/year), predominantly with cervical Mycobacterium avium complex (MAC) adenitis. Surprisingly, based on more than half a million clinical specimens cultured for mycobacteria in Denmark through 25 years, the NTM disease burden and trend in incidence in the Danish population has not increased opposed to numerous internationals reports.

Risk factors of non-tuberculous mycobacterial lymphadenitis in children: a case-control study

The aim of the present study is to clarify the association between environmental exposures and non-tuberculous mycobacterial (NTM) lymphadenitis, during the last decade, in a population of children. In children up to 14 years of age in a pediatric tertiary hospital, all cases of NTM lymphadenopathy with a specific microbiological diagnosis, from January 2004 to January 2015, were reviewed. This is a case-control study (1:5 proportion), in which the prevalence of environmental factors between cases and controls was compared by means of a multivariate logistic regression analysis. A total of 24 cases were diagnosed in the aforementioned period, and 18 of them included in the case-control study. Mycobacterium avium-intracellulare was the predominant mycobacterium species isolated (83.3%). Exposure to hens showed a clear trend to be significantly associated with the disease (OR = 4.33; IC95% 0.97-19.41, p = 0.055), with no significant differences for the rest of the risk factors studied.

CONCLUSION

M. avium is still the predominant bacteria causing NTM lymphadenitis in children of our region. Contact with hens has been the only risk factor for NTM lymphadenitis detected in the present study. What is Known: • M. avium is the predominant bacteria causing NTM lymphadenitis in children of our region. • There is no consensus on which environmental factors are associated with NTM lymphadenitis in children. What is New: • The only risk factor for NTM lymphadenitis found in the present study was regular contact with hens. Contact with other farm animals was not associated to NTM lymphadenitis.

Pinpointing the source of infection of Mycobacterium avium hominissuis in children

Mycobacterium avium hominissuis is the most important causative agent of chronic nontuberculous lymphadenitis in children. Despite a ubiquitous occurrence of the bacteria in the environment, the disease is a rare entity, and so far no source of infection has been formally identified. The current state of knowledge regarding possible sources of M. avium hominissuis, especially where children are concerned, is summarized here. An analysis of the seasonal variation of M. avium lymphadenitis in children leads to a new hypothesis regarding the probable source of infection of M. avium hominissuis, where global trade of alimentary products might be involved.

Environmental reservoirs of pathogenic mycobacteria across the Ethiopian biogeographical landscape

The Mycobacterium genus comprises over one-hundred-and-fifty recognised species, the majority of which reside in the environment and many of which can be pathogenic to mammals. Some species of environmental mycobacteria may interfere with BCG vaccination efficacy and in tuberculin test interpretation. Examining biogeographic trends in the distribution of members of the mycobacteria across a number of physicochemical and spatial gradients in soil and water environments across Ethiopia using oligotyping identified differential distributions of pathogenic and significant species. The tuberculosis complex was identified in more than 90% of water samples and taxonomic groups implicated in lower BCG vaccine efficiency were core in both soil and water Mycobacterium communities. A reservoir of Mycobacterium bovis was identified in water, with up to 7.3×102 genome equivalents per ml. Elevation, temperature, habitat and vegetation type were important predictors of both soil and water Mycobacterium communities. These results represent the first step in understanding the potential risk of exposure to environmental mycobacteria that may undermine efforts to reduce disease incidence.

Estimating Tuberculin Skin Test Reactions among Children and Teenagers Who Received the Bacillus Calmette-Guerin Vaccination at Birth: A Meta-analysis

OBJECTIVES

Tuberculin skin reaction size is one indicator of bacillus Calmette-Guérin (BCG) vaccine efficacy and a way to diagnose latent infection. Several primary studies have examined this issue. Combining the results of these studies using a meta-analysis will provide reliable evidence regarding this indicator for policymakers. This study aimed to estimate the total frequency of different tuberculin skin test reactions among Iranian children and teenagers who received the BCG vaccination at birth.

METHODS

National and international databanks were searched using relevant keywords. After the search strategy was restricted and duplicates were excluded, the titles and abstracts of the remaining papers were screened. All included studies included healthy children who received the BCG vaccine without confirmed tuberculosis exposure. Heterogeneity of the results was assessed using the Cochrane test and I² index showed the random effects model as the best model for estimating the pooled results.

RESULTS

We combined the results of 14 primary studies including purified protein derivative reaction test measures of 26,281 Iranian children. The frequencies (95% confidence intervals) of the reactions were 8.5% (6.2-10.8) for patients with a reaction size ≥ 10 mm, 29.9% (22.3-37.4) for a reaction size of 5-9 mm, and 60% (48.9-71.1) for a reaction size < 5 mm.

CONCLUSION

Our study showed that large numbers of Iranian children and teens have no positive BCG vaccine reaction and a considerable number of children have been exposed to Mycobacterium tuberculosis.

Use of green fluorescent protein labeled non-tuberculous mycobacteria to evaluate the activity quaternary ammonium compound disinfectants and antibiotics

Although infections with NonTuberculous Mycobacteria have become less common in AIDS patients, they are important opportunistic infections after surgical procedures, likely because they are ubiquitous and not efficiently killed by many commonly used disinfectants. In Venezuela there have recently been many non-tuberculous mycobacteria soft tissue infections after minor surgical procedures, some apparently related to the use of a commercial disinfectant based on a Quaternary Ammonium Compound. We studied the activity of this and other quaternary ammonium compounds on different non-tuberculous mycobacteria by transforming the mycobacteria with a dnaA-gfp fusion and then monitoring fluorescence to gauge the capacity of different quaternary ammonium compounds to inhibit bacterial growth. The minimum inhibitory concentration varied for the different quaternary ammonium compounds, but M. chelonae and M. abscessus were consistently more resistant than M. smegmatis, and M. terrae more resistant than M. bovis BCG.

Impact of industrial structure and soil exposure on the regional variations in pulmonary nontuberculous mycobacterial disease prevalence

OBJECTIVE/BACKGROUND

The prevalence of pulmonary nontuberculous mycobacterial (pNTM) disease, including Mycobacterium avium complex (MAC), varies widely according to geographic region. However, the factors that influence regional variations in pNTM disease prevalence remain unknown. This study was undertaken to examine whether environmental or occupational factors or host traits could influence regional variations in pNTM disease prevalence.

METHODS

We collected laboratory data on pulmonary tuberculosis (pTB) and pNTM from two hospitals in the West Harima area of Japan and five hospitals in Kyoto City, Japan from 2012 to 2013. We estimated microbiological pNTM disease prevalence by multiplying all pTB cases in each area with the ratio of pNTM cases and pTB cases at the survey hospitals in each area. We administered a standardized questionnaire to 52 patients and 120 patients with pulmonary MAC (pMAC) disease at Ako City Hospital and Kyoto University Hospital, respectively.

RESULTS

The estimated prevalence of microbiological pNTM disease in the West Harima area (85.4/100,000 population-years) was significantly higher than that observed in Kyoto City (23.6/100,000 population-years; p<.001). According to multiple logistic regression analysis, in Ako City Hospital, primary (activities directly related to natural resources) and secondary industries (construction, mining, and manufacturing primary industry produce; odds ratio [OR]=4.79; 95% confidence interval [CI]=1.49-14.0; p=.007) and soil exposure (OR=13.6; 95% CI=4.94-45.26; p<.001) were associated with pMAC disease.

CONCLUSION

Environmental factors, both industrial structures associated with occupational dust and environmental soil exposure, could influence the regional variations in pNTM disease prevalence.

Disseminated Mycobacterium avium Complex With Cutaneous Lesions

BACKGROUND

Although most commonly encountered in patients with human immunodeficiency virus infection, disseminated Mycobacterium avium complex (MAC) is becoming more common in patients receiving immunosuppressive medications. Disseminated MAC with skin lesions may occur, and several presentations have been reported, including panniculitis, cutaneous granulomas, pustules, ulcerations, and erythematous skin lesions.

OBJECTIVES

The objective of this report is to describe an unusual presentation of MAC that is unlikely to be encountered frequently in the outpatient dermatology setting, especially in a patient without human immunodeficiency virus infection.

METHODS

The authors present a case of disseminated MAC infection with cutaneous manifestations in an iatrogenically immunocompromised patient.

CONCLUSIONS

Diagnosis of MAC infection is challenging given the varied clinical presentations and the difficulty in culturing MAC. In addition, the acid-fast stain is nonspecific. Clinicians should remember to consider MAC infection in patients with acid-fast-positive skin lesions, as the selection of appropriate antibiotic therapy is species specific.

Middle-aged to elderly women have a higher asymptomatic infection rate with Mycobacterium avium complex, regardless of body habitus

Mycobacterium avium complex (MAC) pulmonary disease is prevalent in middle-aged to elderly women with a thin body habitus. By comparing the rate of serologically diagnosed asymptomatic MAC infection and body mass index among 1033 healthy subjects, we find that middle-aged to elderly women became infected with MAC, regardless of their body habitus.

Experimental Reactivation of Pulmonary Mycobacterium avium Complex Infection in a Modified Cornell-Like Murine Model

The latency and reactivation of Mycobacterium tuberculosis infection has been well studied. However, there have been few studies of the latency and reactivation of Mycobacterium avium complex (MAC), the most common etiological non-tuberculous Mycobacterium species next to M. tuberculosis in humans worldwide. We hypothesized that latent MAC infections can be reactivated following immunosuppression after combination chemotherapy with clarithromycin and rifampicin under experimental conditions. To this end, we employed a modified Cornell-like murine model of tuberculosis and investigated six strains consisting of two type strains and four clinical isolates of M. avium and M. intracellulare. After aerosol infection of each MAC strain, five to six mice per group were euthanized at 2, 4, 10, 18, 28 and 35 weeks post-infection, and lungs were sampled to analyze bacterial burden and histopathology. One strain of each species maintained a culture-negative state for 10 weeks after completion of 6 weeks of chemotherapy, but was reactivated after 5 weeks of immunosuppression in the lungs with dexamethasone (three out of six mice in M. avium infection) or sulfasalazine (four out of six mice in both M. avium and M. intracellulare infection). The four remaining MAC strains exhibited decreased bacterial loads in response to chemotherapy; however, they remained at detectable levels and underwent regrowth after immunosuppression. In addition, the exacerbated lung pathology demonstrated a correlation with bacterial burden after reactivation. In conclusion, our results suggest the possibility of MAC reactivation in an experimental mouse model, and experimentally demonstrate that a compromised immune status can induce reactivation and/or regrowth of MAC infection.

Identification and genotyping of Mycobacterium tuberculosis isolated from water and soil samples of a metropolitan city

BACKGROUND

The potential role of environmental Mycobacterium tuberculosis in the epidemiology of TB remains unknown. We investigated the transmission of M tuberculosis from humans to the environment and the possible transmission of M tuberculosis from the environment to humans.

METHODS

A total of 1,500 samples were collected from three counties of the Tehran, Iran metropolitan area from February 2012 to January 2014. A total of 700 water samples (47%) and 800 soil samples (53%) were collected. Spoligotyping and the mycobacterial interspersed repetitive units-variable number of tandem repeats typing method were performed on DNA extracted from single colonies. Genotypes of M tuberculosis strains isolated from the environment were compared with the genotypes obtained from 55 patients with confirmed pulmonary TB diagnosed during the study period in the same three counties.

RESULTS

M tuberculosis was isolated from 11 of 800 soil samples (1%) and 71 of 700 water samples (10%). T family (56 of 82, 68%) followed by Delhi/CAS (11 of 82, 13.4%) were the most frequent M tuberculosis superfamilies in both water and soil samples. Overall, 27.7% of isolates in clusters were related. No related typing patterns were detected between soil, water, and clinical isolates. The most frequent superfamily of M tuberculosis in clinical isolates was Delhi/CAS (142, 30.3%) followed by NEW-1 (127, 27%). The bacilli in contaminated soil (36%) and damp water (8.4%) remained reculturable in some samples up to 9 months.

CONCLUSIONS

Although the dominant M tuberculosis superfamilies in soil and water did not correspond to the dominant M tuberculosis family in patients, the presence of circulating genotypes of M tuberculosis in soil and water highlight the risk of transmission.

Environmental risks for nontuberculous mycobacteria. Individual exposures and climatic factors in the cystic fibrosis population

RATIONALE

Persons with cystic fibrosis are at high risk of pulmonary nontuberculous mycobacterial infection, with a national prevalence estimated at 13%. The risk of nontuberculous mycobacteria associated with specific environmental exposures, and the correlation with climatic conditions in this population has not been described.

OBJECTIVES

To describe the association of pulmonary nontuberculous mycobacteria with individual exposures to water and soil aerosols, and the population associations of these infections with climatic factors.

METHODS

We conducted a nested case-control study within a cohort study of pulmonary nontuberculous mycobacteria prevalence at 21 geographically diverse national cystic fibrosis centers. Incident nontuberculous mycobacterial infection cases (at least one prior negative culture followed by one positive culture) were age- and sex-matched to culture-negative controls. Exposures to water and soil were assessed by administering a standardized questionnaire. Cohort prevalence at each of the 21 centers was correlated with climatic conditions in the same area through linear regression modeling.

MEASUREMENTS AND MAIN RESULTS

Overall, 48 cases and 85 control subjects were enrolled. Indoor swimming was associated with incident infection (adjusted odds ratio, 5.9, 95% confidence interval, 1.3-26.1), although only nine cases (19%) and five control subjects (6%) reported indoor swimming in the 4 months prior to infection. Exposure to showering and municipal water supply was common among both cases and control subjects: 77% of cases and 76% of control subjects reported showering at least daily. In linear regression, average annual atmospheric water vapor content was significantly predictive of center prevalence (P = 0.0019), with R(2) = 0.40.

CONCLUSIONS

Atmospheric conditions explain more of the variation in disease prevalence than individual behaviors. The risk of specific exposures may vary by geographic region due to differences in conditions favoring mycobacterial growth and survival. However, because exposure to these organisms is ubiquitous and behaviors are similar among persons with and without pulmonary nontuberculous mycobacteria, genetic susceptibility beyond cystic fibrosis is likely to be important for disease development. Common individual risk factors in high-risk populations remain to be identified.

Isolation of Mycobacterium avium from Potable Water in Homes and Institutions of Patients with HIV Infection in Finland and the United States

Symptomatic disease by nontuberculous mycobacteria has been linked to potable water from institutional and domestic potable water systems. Potable water samples were collected from homes and institutions of patients with AIDS. Colonization of potable water with nontuberculous mycobacteria was demonstrated in 230 (15%) of 1489 samples collected from domestic and institutional water systems of patients with HIV infection in the United States and Finland. Mycobacterium avium was the most common species and colonization was favored at temperatures of 40–50°C in recirculating hot water systems. Such systems are a plausible source of human infection and disease.

Epidemiology and clinical features of pulmonary nontuberculous mycobacteriosis in Nagasaki, Japan

BACKGROUND AND OBJECTIVES

Recent reports indicate that the incidence of nontuberculous mycobacterial-lung disease (NTM-LD) is increasing. This study aimed to investigate the epidemiology and clinical features of NTM-LD patients in Nagasaki prefecture, Japan to identify the negative prognostic factors for NTM-LD in Japan.

METHODS

The medical records of patients newly diagnosed with NTM-LD in eleven hospitals in Nagasaki prefecture between January 2001 and February 2010 were reviewed. Data regarding the annual population of each region and the incidence of all forms of tuberculosis were collected to assess geographic variations in NTM-LD incidence, isolates, and radiological features.

RESULTS

A total 975 patients were diagnosed with NTM-LD. The incidence increased over the study period and reached 11.0 and 10.1 per 100,000 population in 2008 and 2009, respectively. M. intracellulare was the most common pathogen in the southern region, and M. avium most common in other regions. The most common radiographic pattern was the nodular-bronchiectatic pattern. Age >60 years, body mass index <18.5 kg/m2, underlying lung disease, and cavitary pattern were the negative prognostic factors at the 1-year follow-up.

CONCLUSIONS

The incidence of NTM-LD has been increasing in Nagasaki prefecture. The isolates and radiographic features of patients vary markedly by region.

Review: Environmental mycobacteria as a cause of human infection

Pulmonary infections with nontuberculous mycobacteria (NTM) are recognized as a problem in immunodeficient individuals and are increasingly common in older people with no known immune defects. NTM are found in soil and water, but factors influencing transmission from the environment to humans are mostly unknown. Studies of the epidemiology of NTM disease have matched some clinical isolates of NTM with isolates from the patient's local environment. Definitive matching requires strain level differentiation based on molecular analyses, including partial sequencing, PCR-restriction fragment length polymorphism (RFLP) analysis, random amplified polymorphic DNA (RAPD) PCR, repetitive element (rep-) PCR and pulsed field gel electrophoresis (PFGE) of large restriction fragments. These approaches have identified hospital and residential showers and faucets, hot-tubs and garden soil as sources of transmissible pathogenic NTM. However, gaps exist in the literature, with many clinical isolates remaining unidentified within environments that have been tested, and few studies investigating NTM transmission in developing countries. To understand the environmental reservoirs and transmission routes of pathogenic NTM, different environments, countries and climates must be investigated.

The epidemiology and geographic distribution of nontuberculous mycobacteria clinical isolates from sputum samples in the eastern region of China

Background

Nontuberculous mycobacteria (NTM) have been reported to be increasing worldwide and its geographic distribution differs by region. The aim of this study was to describe the epidemiology and distribution of NTM in the eastern part of China.

Methods

Sputum samples were collected from 30 surveillance sites for tuberculosis drug resistance test from May 1, 2008 to December 31, 2008. Identification was performed using a biochemical test, multiplex PCR and GenoType Mycobacterium CM/AS assay.

Results

A total of 1779 smear positive clinical isolates were obtained, of which 60 (3.37%) were NTM. Five species/complex of NTM were identified; M. intracellulare was the predominated species (68.33%), followed by M. abscessus-M. immunogenum (13.33%), Mycobacterium spec. (10.00%), M. Kansasii (6.67%) and M. peregrinum-M. alvei-M. septicum (1.67%).

Conclusion

M. intracellulare was the main species of NTM in the eastern part of China and clinical physicians should pay more attention to NTM induced pulmonary disease.

Nontuberculous mycobacteria (NTM) exist ubiquitously in the environment and cause many kinds of diseases including pulmonary infection. Despite this, NTM does not match compulsory report policy in many countries, such as China. Thus, the epidemiology of NTM is generally unknown. Furthermore, misdiagnosis of nontuberculous mycobacterium disease as multi-drug resistant tuberculosis (MDR-TB) frequently occurs in clinical settings because of similar clinical manifestations. Therefore, elucidating the epidemiology and distribution of NTM species is important and may have a profound and lasting impact on the prevalence of pulmonary NTM disease. In our study, we enrolled smear-positive sputum samples during 2008 from Jiangsu province in the eastern region of China. Traditional biochemical tests and molecular biological methods were performed to distinguish NTM isolates to species/complex level. For the first time, we provide a snapshot of the epidemiology and geographic distribution of NTM in Jiangsu province. The proportion of NTM was 3.37% of all the Mycobacterium isolates and the species of NTM differed by area.

Evaluation of quantitative polymerase chain reaction assays targeting Mycobacterium avium, M. intracellulare, and M. avium subspecies paratuberculosis in drinking water biofilms

Mycobacterium avium (MA), Mycobacterium intracellulare (MI), and Mycobacterium avium subsp. paratuberculosis (MAP) are difficult to culture due to their slow growing nature. A quantitative polymerase chain reaction (qPCR) method for the rapid detection of MA, MI, and MAP can be used to provide data supporting drinking water biofilms as potential sources of human exposure. The aim of this study was to characterize two qPCR assays targeting partial 16S rRNA gene sequences of MA and MI and use these assays, along with two previously reported MAP qPCR assays (IS900 and Target 251), to investigate Mycobacterium occurrence in kitchen faucet biofilms. MA and MI qPCR assays demonstrated 100% specificity and sensitivity when evaluated against 18 non-MA complex, 76 MA, and 17 MI isolates. Both assays detected approximately 1,000 cells from a diluted cell stock inoculated on a sampling swab 100% of the time. DNA analysis by qPCR indicated that 35.3, 56.9 and 11.8% of the 51 kitchen faucet biofilm samples collected contained MA, MI, and MAP, respectively. This study introduces novel qPCR assays designed to specifically detect MA and MI in biofilm. Results support the use of qPCR as an alternative to culture for detection and enumeration of MA, MI, and MAP in microbiologically complex samples.

Spatial clusters of nontuberculous mycobacterial lung disease in the United States

RATIONALE

Prevalence of pulmonary nontuberculous mycobacterial (PNTM) disease varies by geographic region, yet the factors driving these differences remain largely unknown.

OBJECTIVES

To identify spatial clusters of PNTM disease at the county level and to describe environmental and sociodemographic factors predictive of disease.

METHODS

PNTM cases identified from a nationally representative sample of Medicare Part B beneficiaries from 1997 to 2007 were geocoded by county and state of residence. County-level PNTM case counts and Medicare population data were then uploaded into SaTScan to identify significant spatial clusters and low-risk areas of disease. High-risk and low-risk counties were then compared to identify significant sociodemographic and environmental differences.

MEASUREMENTS AND MAIN RESULTS

We identified seven significant (P < 0.05) clusters of PNTM cases. These high-risk areas encompassed 55 counties in 8 states, including parts of California, Florida, Hawaii, Louisiana, New York, Oklahoma, Pennsylvania, and Wisconsin. Five low-risk areas were also identified, which encompassed 746 counties in 23 states, mostly in the Midwest. Counties in high-risk areas were significantly larger, had greater population densities, and higher education and income levels than low-risk counties. High-risk counties also had higher mean daily potential evapotranspiration levels and percentages covered by surface water, and were more likely to have greater copper and sodium levels in the soil, although lower manganese levels.

CONCLUSIONS

Specific environmental factors related to soil and water exposure appear to increase the risk of PNTM infection. Still, given that environmental sources of NTM are ubiquitous and PNTM disease is rare, both host susceptibility and environmental factors must be considered in explaining disease development.

Environmental risk factors for pulmonary Mycobacterium avium-intracellulare complex disease

BACKGROUND

Mycobacterium avium-intracellulare complex (MAC) is a ubiquitous pathogen found in soil and water. Environmental exposure is the primary route for MAC infection. However, specific environmental risk factors have been poorly determined in immunocompetent patients with pulmonary MAC disease.

METHODS

A case-control study was performed with 106 patients with pulmonary MAC disease (men [women], 23 [83]; age, 64.3 ± 9.2 years) and 53 age-matched control patients with bronchiectasis but not pulmonary MAC infection (men [women], 7[46]; age, 63.0 ± 11.0 years). All participants completed a standardized questionnaire that included questions about medical history, smoking history, alcohol usage, age at menopause, and environment exposures. Environment exposures included soil exposure from farming or gardening; water exposure from bathing, showering, hot tub use, dishwashing, swimming, and drinking water; and pet exposure.

RESULTS

No differences were identified in the patient characteristics and underlying diseases. More case patients experienced high soil exposure (≥ 2 per week) than control patients (23.6% vs 9.4%, P = .032); this remained significant after multivariate analysis (OR, 5.9; 95% CI, 1.4-24.7; P = .015). There were no significant differences in other environmental exposures. Case patients with high soil exposure were significantly older than those with low soil exposure (67.3 ± 7.3 years vs 64.3 ± 9.5 years, P = .037). Other characteristics, underlying diseases, and mycobacterial species did not differ between the two groups.

CONCLUSIONS

Patients with pulmonary MAC disease had significantly more soil exposure than noninfected control patients, which suggests that environmental soil exposure is a likely risk factor for the development of pulmonary MAC disease.

"Mycobacterium avium subsp. hominissuis" in neck lymph nodes of children and their environment examined by culture and triplex quantitative real-time PCR

"Mycobacterium avium subsp. hominissuis" often causes cervical lymphadenitis in children; its prompt and accurate identification enables adequate therapy, tracing, and prevention. The aims of this study were to determine the causative agent of lymphadenitis using culture, PCR, and triplex quantitative real-time PCR (qPCR) methods with DNA directly isolated from tissue, as well as to identify possible sources of infection from the environment. We confirmed the diagnoses by detecting M. avium subsp. hominissuis using qPCR with DNA directly isolated from lymph node biopsy specimens of two patients. In order to trace the source of infection from the environment, a method of DNA isolation from soil and other environmental samples, such as dust, cobwebs, and compost, was developed. The triplex qPCR examination revealed the presence of M. avium subsp. hominissuis in a high proportion of the environmental samples (42.8% in the first patient's house and 47.6% in the second patient's house). Both patients were also exposed to M. avium subsp. avium, which was present due to the breeding of infected domestic hens. The high infectious dose of M. avium subsp. hominissuis or the increased susceptibility of humans to M. avium subsp. hominissuis compared to M. avium subsp. avium could be the reason why the children were infected with M. avium subsp. hominissuis.

Revisiting rates of reactivation tuberculosis: a population-based approach

RATIONALE

Reactivation tuberculosis (TB) occurs as a result of reactivation of latent TB infection (LTBI), and was reported to occur in the United States at a rate of 0.10 to 0.16 cases per 100 person-years in the 1950s; it has not been measured since.

OBJECTIVES

To calculate the rate of reactivation TB in a U.S. community.

METHODS

A population-based tuberculin skin test survey for LTBI was performed in western Palm Beach County, Florida, from 1998 to 2000 along with a cluster analysis of TB case isolates in the same area from 1997 to 2001. Reactivation (unclustered) TB was presumed to have arisen from the population with LTBI.

MEASUREMENTS AND MAIN RESULTS

The rate of reactivation TB among persons with LTBI without HIV infection was 0.040 cases per 100 person-years (95% confidence interval [CI], 0.024-0.067) using the n method and 0.058 cases per 100 person-years (95% CI, 0.038-0.089) using the n-1 method. HIV infection was the strongest risk factor for reactivation (rate ratio [RR], 57; 95% CI, 27-120; P < 0.001). Among persons without HIV infection, reactivation was increased among those older than 50 years (RR, 3.8; 95% CI, 1.3-11) and among those born in the United States (RR, 3.2; 95% CI, 1.1-9.3).

CONCLUSIONS

Rates of reactivation TB in this area have declined substantially since the 1950s. The greatest part of this decline may be attributed to the disappearance of old, healed TB in the population. If similar declines are seen in other areas of the United States, the cost-effectiveness of screening and treatment of LTBI may be substantially less than previously estimated.

Skin and soft-tissue infection caused by non-tuberculous mycobacteria in Taiwan, 1997–2008

The aim of this study was to investigate the clinical, microbiological, and pathological characteristics and the outcomes of skin and soft-tissue infection (SSTI) caused by non-tuberculous mycobacteria (NTM). Medical records of 50 patients with SSTI caused by NTM identified from 2005 to 2008 and 63 patients previously reported in a medical centre from 1997 to 2004 were reviewed. The annual incidence (per 100 000 outpatients and in-patients) ranged from 0·57 in 2005, 0·38 in 2007, to 1·1 in 2008, with an average of 0·62/100 000. From 1997 to 2008, the average incidence was 1·39/100 000 patients. The average annual incidence of SSTI caused by NTM was 0·62/100 000 outpatients and in-patients during 2005 and 2008. Of the total of 113 patients identified during the 12-year period, patients infected withMycobacterium fortuitumandM. marinumwere younger than those infected withM. avium-intracellularecomplex (MAC) (36 and 44 yearsvs. 55 years,P=0·004 andP=0·056, respectively), and were more likely to have previous invasive procedures than those infected with MAC andM. abscessus(81·8% and 72·0%vs. 27·8% and 54·8%,P=0·007), and less likely to have associated immunosuppression (9·1% and 24%vs. 66·7% and 45·2%,P=0·006). Granuloma was more often observed in immunocompetent patients (60·1%vs. 40%,P=0·019), and inM. marinum-infected specimens (78·3%). There were significant differences in the demographic and clinical features of patients with NTM SSTI, including immunosuppression, trauma experience, and depth of tissue infections.

Genotyping of Mycobacterium avium complex organisms using multispacer sequence typing

Mycobacterium avium complex (MAC) currently comprises eight species of environmental and animal-associated, slowly-growing mycobacteria: Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium chimaera, Mycobacterium colombiense, Mycobacterium arosiense , Mycobacterium bouchedurhonense, Mycobacterium marseillense and Mycobacterium timonense. In humans, MAC organisms are responsible for opportunistic infections whose unique epidemiology remains poorly understood, in part due to the lack of a genotyping method applicable to all eight MAC species. In this study we developed multispacer sequence typing (MST), a sequencing-based method, for the genotyping of MAC organisms. An alignment of the genome sequence of M. avium subsp. hominissuis strain 104 and M. avium subsp. paratuberculosis strain K-10 revealed 621 intergenic spacers <1000 bp. From these, 16 spacers were selected that ranged from 300 to 800 bp and contained a number of variable bases, <50 within each of the 16 spacers. Four spacers were successfully PCR-amplified and sequenced in 11 reference strains. Combining the sequence of these four spacers in 106 MAC organisms, including 83 M. avium, 11 M. intracellulare , six M. chimaera, two M. colombiense and one each of M. arosiense, M. bouchedurhonense, M. marseillense and M. timonense, yielded a total of 45 spacer types, with an index of discrimination of 0.94. Each spacer type was specific for a species and certain spacer types were specific for subspecies of M. avium. MST is a new method for genotyping of organisms belonging to any one of the eight MAC species tested in this study.

Surrounded by mycobacteria: nontuberculous mycobacteria in the human environment

A majority of the Mycobacterium species, called the nontuberculous mycobacteria (NTM), are natural inhabitants of natural waters, engineered water systems, and soils. As a consequence of their ubiquitous distribution, humans are surrounded by these opportunistic pathogens. A cardinal feature of mycobacterial cells is the presence of a hydrophobic, lipid-rich outer membrane. The hydrophobicity of NTM is a major determinant of aerosolization, surface adherence, biofilm-formation, and disinfectant- and antibiotic resistance. The NTM are oligotrophs, able to grow at low carbon levels [>50 microg assimilable organic carbon (AOC) l(-1)], making them effective competitors in low nutrient, and disinfected environments (drinking water). Biofilm formation and oligotrophy lead to survival, persistence, and growth in drinking water distribution systems. In addition to their role as human and animal pathogens, the widespread distribution of NTM in the environment, coupled with their ability to degrade and metabolize a variety of complex hydrocarbons including pollutants, suggests that NTM may be agents of nutrient cycling.