Clinical significance of Mycobacterium fortuitum isolated from respiratory specimens

Characterisation and antimicrobial susceptibility pattern of non-tuberculous mycobacteria

Background

Non-tuberculous mycobacteria (NTM) management comprises prolonged therapy that includes macrolides. Non-tuberculous mycobacteria can cause disease in patients with predisposing conditions such as HIV and structural lung disease. Local data on NTM disease and macrolide resistance are scarce, and routine antimicrobial susceptibility testing is currently not performed for NTM in South Africa.

Objectives

This study aims to characterise NTM isolated at Tshepong National Health Laboratory Service (NHLS) according to species and antimicrobial susceptibility pattern.

Method

A retrospective data analysis of NTM isolates from Tshepong NHLS was performed from January to June 2020. GenoType® NTM-DR was performed on selected isolates where the assay can confirm the species and determine resistance to macrolides and aminoglycosides.

Results

Of the 194 collected NTM isolates, 183 were included in the study. Patients' ages ranged from 1 day to 81 years (median 36 years). The most common specimen was sputum (84.7%), followed by gastric aspirate (6.6%). The most common NTM isolated were Mycobacterium (M.) intracellulare (67.6%), M. fortuitum (12.6%), M. species (4.3%), M. kansasii (3.9%), and M. scrofulaceum (3.9%). Macrolide resistance occurred in 2.8% of tested isolates; no aminoglycoside resistance was detected. Although most isolates were from males (62.3%), resistance was observed only in females.

Conclusion

M. intracellulare predominated, with only two M. intracellulare and two M. abscessus isolates showing macrolide resistance; aminoglycoside resistance was absent.

Contribution

This study highlights the need for increased awareness of NTM, regular nationwide NTM surveillance, and monitoring of resistance trends to guide future patient management and ensure good treatment outcomes.

Clinical Characteristics and Treatment Outcomes of Mycobacterium fortuitum Pulmonary Disease

We evaluated the clinical characteristics and treatment outcomes of 35 patients diagnosed with Mycobacterium fortuitum-pulmonary disease (M. fortuitum-PD). Prior to treatment, all isolates were sensitive to amikacin and 73% and 90% were sensitive to imipenem and moxifloxacin, respectively. Approximately two-thirds of the patients (24 of 35) remained stable without antibiotic treatment. Of 11 patients requiring antibiotic treatment, the majority (81%, 9 of 11) achieved a microbiological cure with susceptible antibiotics. IMPORTANCE Mycobacterium fortuitum (M. fortuitum) is a rapidly growing mycobacterium that causes M. fortuitum-pulmonary disease (PD). It is common among individuals with preexisting lung conditions. Limited data exist regarding treatment and prognosis. Our study examined patients with M. fortuitum-PD. Two-thirds of them remained stable without antibiotics. Among those requiring treatment, 81% achieved a microbiological cure with suitable antibiotics. In many cases, M. fortuitum-PD follows a stable course without antibiotics, and when necessary, a favorable treatment response can be achieved with the appropriate antibiotics.

In Vitro and In Vivo Efficacy of NITD-916 against Mycobacterium fortuitum

Mycobacterium fortuitum represents one of the most clinically relevant rapid-growing mycobacterial species. Treatments are complex due to antibiotic resistance and to severe side effects of effective drugs, prolonged time of treatment, and co-infection with other pathogens. Herein, we explored the activity of NITD-916, a direct inhibitor of the enoyl-ACP reductase InhA of the type II fatty acid synthase in Mycobacterium tuberculosis. We found that this compound displayed very low MIC values against a panel of M. fortuitum clinical strains and exerted potent antimicrobial activity against M. fortuitum in macrophages. Remarkably, the compound was also highly efficacious in a zebrafish model of infection. Short duration treatments were sufficient to significantly protect the infected larvae from M. fortuitum-induced killing, which correlated with reduced bacterial burdens and abscesses. Biochemical analyses demonstrated an inhibition of de novo synthesis of mycolic acids. Resolving the crystal structure of the InhAMFO in complex with NAD and NITD-916 confirmed that NITD-916 is a direct inhibitor of InhAMFO. Importantly, single nucleotide polymorphism leading to a G96S substitution in InhAMFO conferred high resistance levels to NITD-916, thus resolving its target in M. fortuitum. Overall, these findings indicate that NITD-916 is highly active against M. fortuitum both in vitro and in vivo and should be considered in future preclinical evaluations for the treatment of M. fortuitum pulmonary diseases.

Comparative genome analysis reveals high-level drug resistance markers in a clinical isolate of Mycobacterium fortuitum subsp. fortuitum MF GZ001

Introduction

Infections caused by non-tuberculosis mycobacteria are significantly worsening across the globe. M. fortuitum complex is a rapidly growing pathogenic species that is of clinical relevance to both humans and animals. This pathogen has the potential to create adverse effects on human healthcare.

Methods

The MF GZ001 clinical strain was collected from the sputum of a 45-year-old male patient with a pulmonary infection. The morphological studies, comparative genomic analysis, and drug resistance profiles along with variants detection were performed in this study. In addition, comparative analysis of virulence genes led us to understand the pathogenicity of this organism.

Results

Bacterial growth kinetics and morphology confirmed that MF GZ001 is a rapidly growing species with a rough morphotype. The MF GZ001 contains 6413573 bp genome size with 66.18 % high G+C content. MF GZ001 possesses a larger genome than other related mycobacteria and included 6156 protein-coding genes. Molecular phylogenetic tree, collinearity, and comparative genomic analysis suggested that MF GZ001 is a novel member of the M. fortuitum complex. We carried out the drug resistance profile analysis and found single nucleotide polymorphism (SNP) mutations in key drug resistance genes such as rpoB, katG, AAC(2')-Ib, gyrA, gyrB, embB, pncA, blaF, thyA, embC, embR, and iniA. In addition, the MF GZ001strain contains mutations in iniA, iniC, pncA, and ribD which conferred resistance to isoniazid, ethambutol, pyrazinamide, and para-aminosalicylic acid respectively, which are not frequently observed in rapidly growing mycobacteria. A wide variety of predicted putative potential virulence genes were found in MF GZ001, most of which are shared with well-recognized mycobacterial species with high pathogenic profiles such as M. tuberculosis and M. abscessus.

Discussion

Our identified novel features of a pathogenic member of the M. fortuitum complex will provide the foundation for further investigation of mycobacterial pathogenicity and effective treatment.

Lungenerkrankung durch seltenere nicht-tuberkulöse Mykobakterien – Neue internationale Empfehlungen

Therapie von NTM-Infektionen Für die Behandlung von NTM-Infektionen der Lungen stehen erstmals Evidenz-basierte internationale Leitlinien zur Verfügung. Nach der ersten Publikation der neuen ATS/ERS/ESCMID- und IDSA-Leitlinien zur Behandlung von Lungenerkrankungen durch M. avium complex, M. kansasii, M. xenopi und M. abscessus von 2020 liegen nun weitere Empfehlungen zur Behandlung von selteneren Lungenerkrankungen durch NTM vor.

Relevante NTM-Spezies Die neuen Empfehlungen umfassen Lungenerkrankungen durch die schnellwachsenden Mykobakterien M. chelonae und M. fortuitum sowie durch die langsam-wachsenden Mykobakterien M. genavense, M. gordonae, M. malmoense, M. simiae und M. szulgai.

Anaerobes and methanogens dominate the microbial communities in water harvesting ponds used by Kenyan rural smallholder farmers

Many rural smallholder farmers in Kenya use water-harvesting ponds, to collect rainwater, as sustainable sources of water for domestic and agricultural purposes. There is currently limited information regarding the microbial ecology in these ponds. Here, we used High Throughput Sequencing (HTS) to characterize the microorganisms present (including potential pathogens and indicator species) alongside ion chromatography to measure water chemistry (anion and cation concentration). Fluoride and magnesium concentration were the strongest predictor variables of the microbial community. Obligately or facultatively anaerobic bacterial genera (e.g. Spirochaeta and Opitutus) were abundant within the bacterial community, whilst Woesearchaeota and methanogens dominated the archaeal community. This suggests the water in the ponds is hypoxic or anoxic, and if used for irrigation, may potentially impact crop yield and viability. In addition, the opportunistic pathogen non-tuberculous mycobacteria (NTM), Mycobacterium fortuitum was found, comprising >1% of the bacterial community, suggesting a potential human health risk. Here we suggest low-cost changes to pond management, to improve or ameliorate pond anoxia and remove pathogens to benefit the livelihoods and welfare of these farms. This study also shows the applicability of HTS to broadly screen the microbial communities, assess water quality, and identify potentially pathogenic groups.

Management of patients with pulmonary mycobacteriosis in France: a multicenter retrospective cohort study

Background

Recent studies report very low adherence of practitioners to ATS/IDSA recommendations for the treatment of nontuberculous mycobacteria pulmonary disease (NTM-PD), as well as a great variability of practices. Type of management could impact prognosis.

Methods

To evaluate management and prognosis of patients with NTM-PD cases with respect to ATS recommendations, we conducted a multicenter retrospective cohort study (18 sentinel sites distributed throughout France), over a period of six years. We collected clinical, radiological, microbiological characteristics, management and outcome of the patients (especially death or not).

Results

477 patients with NTM-PD were included. Respiratory comorbidities were found in 68% of cases, tuberculosis sequelae in 31.4% of patients, and immunosuppression in 16.8% of cases. The three most common NTM species were Mycobacterium avium complex (60%), M. xenopi (20%) and M. kansasii (5.7%). Smear-positive was found in one third of NTM-PD. Nodulobronchiectatic forms were observed in 54.3% of cases, and cavitary forms in 19.1% of patients. Sixty-three percent of patients were treated, 72.4% of patients with smear-positive samples, and 57.5% of patients with smear-negative samples. Treatment was in adequacy with ATS guidelines in 73.5%. The 2-year mortality was 14.4%. In the Cox regression, treatment (HR = 0.51), age (HR = 1.02), and M. abscessus (3.19) appeared as the 3 significant independent prognostic factors.

Conclusion

These findings highlight the adequacy between French practices and the ATS/IDSA guidelines. Treatment was associated with a better survival.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01701-5.

Disseminated Coinfection by Mycobacterium fortuitum and Talaromyces marneffei in a Non-HIV Case

Background

Mycobacterium fortuitum is a rapidly growing non-tuberculous mycobacterium (NTM) with weak pathogenicity. Here, we present a rare case of disseminated M. fortuitum and Talaromyces marneffei coinfection in a human immunodeficiency virus (HIV) negative patient.

Case Presentation

A 28-year-old female was admitted to our hospital due to 2 months of swelling of lymph nodes on the right side of her cervix, accompanied by repeated low fever for more than 1 month. Biopsy of the right cervical lymph node and endobronchial ultrasound-guided transbronchial fine needle aspiration (EBUS-TBNA) both suggested granulomatous inflammation. The bacterial culture and mycobacteria examination of the lesion as well as HIV antibody test were all negative. Disseminated T. marneffei infection was diagnosed by the quantitative polymerase chain reaction (qPCR) results from the blood showing 1798 copies/ul. In the meantime, treatment with amphotericin B combined with cefoxitin was administered for suspected NTM infection. However, the once-dropped fever recurred and the lymph nodes continued to swell. Metagenomics next-generation sequencing (mNGS) detection of the lymph nodes indicated M. fortuitum. After combination treatment with amphotericin B, voriconazole, linazolamide, and imipenem, the patient's body temperature returned to normal, the lymph node swelling was gradually reduced, and the lung lesion was absorbed.

Conclusion

We report the first case of an HIV-negative patient diagnosed with disseminated M. fortuitum and T. marneffei coinfection with nonspecific clinical manifestation, in order to heighten awareness of these infections.

Phenotypic and genomic hallmarks of a novel, potentially pathogenic rapidly growing Mycobacterium species related to the Mycobacterium fortuitum complex

Previously, we have identified a putative novel rapidly growing Mycobacterium species, referred to as TNTM28, recovered from the sputum of an apparently immunocompetent young man with an underlying pulmonary disease. Here we provide a thorough characterization of TNTM28 genome sequence, which consists of one chromosome of 5,526,191 bp with a 67.3% G + C content, and a total of 5193 predicted coding sequences. Phylogenomic analyses revealed a deep-rooting relationship to the Mycobacterium fortuitum complex, thus suggesting a new taxonomic entity. TNTM28 was predicted to be a human pathogen with a probability of 0.804, reflecting the identification of several virulence factors, including export systems (Sec, Tat, and ESX), a nearly complete set of Mce proteins, toxin-antitoxins systems, and an extended range of other genes involved in intramacrophage replication and persistence (hspX, ahpC, sodA, sodC, katG, mgtC, ClpR, virS, etc.), some of which had likely been acquired through horizontal gene transfer. Such an arsenal of potential virulence factors, along with an almost intact ESX-1 locus, might have significantly contributed to TNTM28 pathogenicity, as witnessed by its ability to replicate efficiently in macrophages. Overall, the identification of this new species as a potential human pathogen will help to broaden our understanding of mycobacterial pathogenesis.

Mycobacterium salmoniphilum and M. chelonae in Captive Populations of Chinook Salmon

Chinook Salmon Oncorhynchus tshawytscha is a keystone fish species in the Pacific Northwest. In 2019, unusual mortalities occurred in two different populations of cultured fingerlings from the same facility in California, USA. The systems consist of outdoor, enclosed, flow-through freshwater tanks that are maintained at 18 ± 1°C. Clinical signs and gross findings were only observed in one population and included abnormal swimming, inappetence, lethargy, skin discoloration, and the presence of multifocal nodular and ulcerative skin lesions. Microscopic lesions were infrequent and consisted of severe, locally extensive granulomatous dermatitis and myositis and mild, multifocal, granulomatous branchitis, myocarditis, and hepatitis. Intracellular acid-fast organisms were observed within areas of granulomatous myositis. Posterior kidney swabs were collected and inoculated in nutrient-rich and selective agar media and incubated at 25°C for 2 weeks. Visibly pure bacterial colonies were observed 7-10 d postinoculation. Partial sequences of 16S rRNA initially identified the recovered bacteria as members of the genus Mycobacterium. However, marked variability was observed among Mycobacterium spp. isolates by using repetitive extragenic palindromic polymerase chain reaction fingerprinting. Amplification and sequencing of the ribosomal RNA internal transcribed spacer, 65-kDa heat shock protein, and RNA polymerase β-subunit gene of the cultured isolates identified M. salmoniphilum and M. chelonae, discrete members of the M. chelonae-abscessus complex, isolated from diseased Chinook Salmon fingerlings.

General characteristics, features of cultivation and antibiotic resistance representatives of mycobacterium fortuitum group representatives (review of literature)

Recently, more and more scientific works have been devoted to non-tuberculous mycobacteria, both by domestic and foreign researchers. One of the main reasons for this is the increase in patients with immunosuppression of various origins, improvement of the quality of laboratory and instrumental diagnostics of mycobacteriosis. This article focuses on the representatives of the M. fortuitum group, as the main pathogens among the group of fast-growing mycobacteria. The data on the modern classification based on the use of molecular genetic studies are indicated. The M. fortuitum group includes: Mycobacterium fortuitum, M. peregrinum, M. senegalense, M. porcinum, M. houstonense, M. neworleansense, M. boenickei, M. conceptionense, M. septicum, M. alvei. According to the new data, mycobacteria were divided into 5 clades (Abscessus-Chelonae, Fortuitum-Vaccae, Terrae, Triviale, Tuberculosis-Simiae), and based on molecular genetic studies, new genera in the Mycobacteriaceae family were isolated: Mycolicibacter spp., Mycolicibacillus spp., Mycolicibacillus spp., Mycobacteroides spp., Mycolicibacterium spp. In accordance with the new classification, representatives of the Mycobacterium fortuitum group belong to the genus Mycolicibacterium. The main epidemiological features of the main sources of the spread of mycobacteria, factors and ways of their transmission are indicated. Due to their wide distribution in the environment, representatives of the M. fortuitum group are capable of causing diseases of the pulmonary and extrapulmonary localization. The distinctive features of pathogenicity factors, due to which the course of the disease is determined, are noted. The article also indicates the main difficulties and features of determining the sensitivity to antimicrobial chemotherapy drugs, provides data on the main features of antibiotic resistance of M.fortuitum group. In preparing the review, literature sources obtained from international and domestic databases were used: Scopus, Web of Science, Springer, RSCI.

Species identification and antimicrobial susceptibility testing of non-tuberculous mycobacteria isolated in Chongqing, Southwest China

With the rapid rise in the prevalence of non-tuberculous mycobacteria (NTM) diseases across the world, the microbiological diagnosis of NTM isolates is becoming increasingly important for the diagnosis and treatment of NTM disease. In this study, the clinical presentation, species distribution and drug susceptibility of patients with NTM disease visiting the Chongqing Public Health Medical Centre during March 2016-April 2019 were retrospectively analysed. Among the 146 patients with NTM disease, eight NTM species (complex) were identified. The predominant NTM species in these patients were identified to be Mycobacterium abscessus complex (53, 36.3%), M. intracellulare (38, 26%) and M. fortuitum (17, 11.7%). In addition, two or more species were isolated from 7.5% of the patients. Pulmonary NTM disease (142, 97.3%) showed the highest prevalence among the patients. It was observed that 40.1% of the patients with pulmonary NTM disease had chronic pulmonary obstructive disease and bronchiectasis, while 22.5% had prior tuberculosis. Male patients showed more association with the conditions of cough and haemoptysis than the female patients. In an in vitro antimicrobial susceptibility testing, most of the species showed susceptibility to linezolid, amikacin and clarithromycin, while M. fortuitum exhibited low susceptibility to tobramycin. In conclusion, the prevalence of NTM disease, especially that of the pulmonary NTM disease, is common in Southwest China. Species identification and drug susceptibility testing are thus extremely important to ensure appropriate treatment regimens for patient care and management.

Mycobaterium fortuitum disseminated infection in an immunocompetent patient without predisposing factors

Most Mycobacterium fortuitum infections described involve direct inoculation through skin lesions. We describe the case of a patient without risk factors who presented with an intracranial mass and a pulmonary infection with M. fortuitum As M. fortuitum are rarely pathogens, there is little knowledge about the optimal treatment and outcome of such infections: what is the best mode of administration, what is the best therapy duration and is surgery always required are some of the unanswered questions. In our patient, surgical removal of the mass associated with a 1-year antimycobacterial therapy led to a full recovery. Even though M. fortuitum was rapidly identified in sputum, it was initially considered non-pathogenic and the definitive diagnosis required almost 6 weeks of investigations. New molecular techniques will probably lead to more identifications of M. fortuitum in the next few years and a better knowledge of their possible pathogenicity and optimal treatment.

Isolation, identification and associated risk factors of non-tuberculous mycobacteria infection in humans and dromedary camels in Samburu County, Kenya

Non-tuberculous mycobacteria are of public health significance, and zoonotic infection is attributed to the sociocultural practice of consumption of raw milk and the close human-livestock contact in pastoral communities. This study aimed at isolation, identification of mycobacteria from human sputum and camel milk and risk factors assessment in Samburu East, Kenya. Six hundred and twelve camels and 48 people presumed to have tuberculosis (TB) from 86 households in Wamba and Waso regions were screened. Camels were categorized into Somali, Turkana and Rendile breeds. Single intradermal comparative tuberculin test (SICTT) was used as a herd-screening test on lactating camels and a milk sample collected from reactive camels. Sputum samples were collected from eligible members of participating households. A standard questionnaire on possible risk factors for both humans and camels was administered to respective household heads or their representatives. Total camel skin test reactors were 238/612 (38.9%). Milk and sputum samples were analysed at KEMRI/TB research laboratory for microscopy, GeneXpert^® , culture and identification. Isolates were identified using 16S rRNA gene sequencing at Inqaba biotec in South Africa. Sixty-four isolates were acid-fast bacilli (AFB) positive of which M. fortuitum (3), M. szulgai (20), M. monacense (5), M. lehmanni (4), M. litorale (4), M. elephantis (3), M. duvalii (3), M. brasiliensis (1), M. arcueilense (1) and M. lentiflavum (1) were from milk; M. fortuitum (1), M. szulgai (2) and M. litorale (1) were from humans. Risk factors included the following: Turkana breed (OR = 3.4; 95% CI: 1.2-9.3), replacements from outside the County (OR = 2.1; 95% CI: 0.3-12.3), presence of other domestic species (small stock; OR = 4.6) and replacement from within the herd (OR = 3.2; 95% CI: 0.7-14.7). Zoonotic risk practices included raw milk consumption, shared housing and handling camels. Monitoring of zoonotic NTM through surveillance and notification systems is required.

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.

Renibacterium salmoninarum and Mycobacterium spp.: two bacterial pathogens present at low levels in wild brown trout (Salmo trutta fario) populations in Austrian rivers

BACKGROUND

Renibacterium salmoninarum and Mycobacterium sp. are important bacterial pathogens of fish. R. salmoninarum is the causative agent of bacterial kidney disease, a Gram-positive bacterium mostly known for causing chronic infections in salmonid fish, while multiple species belonging to the Mycobacterium genus have been associated with mycobacteriosis in fish as well as in human. The objective of this study was to determine the prevalence of these two bacterial pathogens in populations of wild brown trout (Salmo trutta fario) in four rivers (Kamp, Wulka, Traun and Ybbs) in Austria.

RESULTS

A total of 457 kidney samples were examined for both bacterial agents using nested and conventional PCR as well as bacterial cultivation on KDM-2, histological examination and immunohistochemistry. Molecular evidence showed an estimated prevalence level of 0.94% for R. salmoninarum in 2017 while the bacterium could not be detected in 2018 and histology showed signs consistent with a low-level chronic inflammation in the kidney of infected fish. Similarly, no fish were found positive for Mycobacterium in 2017 but in 2018, the prevalence was found to be 37.03% in the Kamp river (4.08% across all rivers). The sequencing data confirmed that these fish carried Mycobacterium sp. although the precise species of Mycobacterium could not be ascertained.

CONCLUSIONS

This survey constitutes the first insight into the prevalence rate of R. salmoninarum and Mycobacterium sp. in wild brown trout (Salmo trutta fario) populations in Austria. Both of these pathogens were only detected in the summer months (June and July), which might suggest that the stress linked to increased water temperature could act as stressor factor and contribute to the outbreak of these diseases. The age of the fish might also play a role, especially in the case of Mycobacterium sp. as all the infected fish were in their first summer (June).

In vivo infection and In vitro stress survival studies of acid susceptible mutant of Mycobacterium fortuitum

Background

Ubiquitous presence of Mycobacterium fortuitum and ability to cause infections in human beings, hints toward its integral resistance against environmental and host stress conditions. With an aim to identify genes responsible for adapting in vitro acidic stress of M. fortuitum, in the previous study, TnphoA random mutagenesis identified acid susceptible mutant MT727, with mutation in ribosomal maturation factor encoding gene rimP, to be mutated. The present study was conducted to explore virulent behavior as well as growth behavior under in vitro stress conditions.

Methods

Acid susceptible transposon mutant MT727 was injected intravenously in female BALB/c mice and kidney tissue was analyzed for the bacillary load as well as pathological characterization. Cytokine profiling of MT727-infected mice serum was done. MT727 was also subjected to various in vitro stress conditions, including detergent stress, heat stress, and hypoxic stress. The viable count of bacteria under different stress conditions was determined at regular time interval.

Results

Mutant MT727 showed slight variation in bacillary load in vivo; however, defective growth behavior under detergent and hypoxic stress was observed when compared to wild type strain.

Conclusion

Results conclude probable involvement of rimP gene in survival of M. fortuitum under hypoxic stress and detergent stress conditions.

Misleading of the diagnosis of Mycobacterium attributed lung diseases to malignancy due to smear, culture and PCR negative results: A lesson from a case report

The incidence of non-tuberculous mycobacteria (NTM) attributed diseases are rising and they are responsible for an increasing proportion of mycobacterial diseases, worldwide. However, their diagnosis is still a big challenge. In this study, a 77-year-old diabetic woman with familial history of lung cancer and 40 pack/year smoking history was presented. She described significant weight loss, shortness of breath, yellow productive sputum, fever, and chills from 4 months ago. The empirical antibiotic therapy didn't cause a significant improvement in the patient's health condition. Also, the sputum smear, culture, and polymerase chain reaction-based (PCR) tests were negative for Mycobacterium tuberculosis (MTB). Computed tomography scanning identified a consolidation at the right upper lobe which was susceptible to malignancy. Non-caseous granulomatous inflammation with the presence of acid-fast bacillus was detected in the biopsies. Therefore, the patient's sputum was reexamined. Although PCR was negative, both smear and culture became positive. PCR-based amplification of a 596 bp fragment of 16S rRNA gene of the isolated bacteria, followed by almost full 16S rRNA sequencing, identified the Mycobacterium fortuitum strain. No malignant cell was detected at pathology evaluations. Due to the increase of NTM attributed diseases which can exhibit negative PCR for MTB and low reliability of negative results of sputum smear and culture, multiple repetitions of the sputum evaluations and, utilizing from 16S rRNA sequencing is recommended to diagnose NTM related lung disease.

Antimicrobial susceptibility patterns and MICs among non-photochromogenic rapidly growing Mycobacteroides and Mycolicibacterium species

Introduction. Non-photochromogenic rapidly growing mycobacteria (NPRGM) that branch distinctly from Mycobacteroides (Myco) and Mycolicibacterium (Mycolici) are increasingly observed clinically and present a complicated treatment challenge; thus, appropriate in vitro susceptibility testing is required.Methodology. We evaluated the MICs of nine antimicrobials used in the treatment of infections of 25 NPRGM type strains. The relation of inducible macrolide resistance with functional erythromycin ribosomal methylase (erm) genes was also investigated.Results. The initial clarithromycin MIC reading at 3 days showed resistance in four of the Mycolici strains. In contrast, the presence of erm genes among Mycolici species differed from previous findings. Both Myco and Mycolici species were highly susceptible to amikacin and linezolid. Myco species were resistant to fluoroquinolones, while Mycolici species were susceptible. Meropenem showed low activity against Myco species, but high activity against Mycolici species.Conclusion. NPRGM clade-specific susceptibility patterns suggest an urgent need to establish distinct breakpoints for Myco and Mycolici species.

Evaluating the clinical significance of nontuberculous mycobacteria isolated from respiratory samples in Iran: an often overlooked disease

Purpose

Nontuberculous mycobacteria (NTM) infection is an increasing problem worldwide whose clinical significance is still largely unknown. The aim of this study was to investigate the epidemiology of NTM infection from respiratory samples and to determine their clinical significance.

Patients and methods

This cross-sectional study was performed on 7,825 clinical samples from December 2015 to December 2017. Detection was conducted using phenotypic and genotypic (hsp65 PCR-RFLP, rpoB, and 16S rRNA genes sequencing) methods. All clinical information including symptoms and radiological findings was extracted from patients’ records.

Results

A total of 478 were confirmed to have respiratory samples which were culture positive for mycobacteria, with the prevalence of NTM infection obtained as 53 (11.1%). Overall, Mycobacterium (M.) fortuitum was the most frequent NTM isolate, followed by M. simiae, M. kansasii, M. gordonae, and M. conceptionense. There was a relationship between NTM isolates and gender (P=0.039), symptoms (P=0.048), and radiographic findings (P=0.013). Bronchiectasis, infiltration, and cavitary lesion were the most frequent radiological findings in M. fortuitum, M. simiae, and M. kansasii, respectively, with cough being the most frequent symptom.

Conclusion

We reported five different NTM isolates in respiratory samples with a high frequency of M. fortuitum. NTM infections may play an important role in causing pulmonary disease and in tuberculosis management in endemic settings. Nevertheless, more studies are required to further examine the clinical significance of NTM isolates.

Clinical and microbiological characteristics of non-tuberculous mycobacteria diseases in Singapore with a focus on pulmonary disease, 2012-2016

Background

Information on non-tuberculosis mycobacterial (NTM) diseases remains limited in Singapore and other Southeast Asian countries. This study aimed to delineate epidemiological and clinical features of pulmonary NTM disease.

Methods

A retrospective review was performed on all NTM isolates identified in Singapore General Hospital from 2012 to 2016 using the 2007 ATS/IDSA diagnostic criteria.

Results

A total of 2026 NTM isolates from 852 patients were identified. M. abscessus-chelonae group (1010, 49.9%) was the most commonly isolated and implicated in pulmonary NTM disease. Pulmonary cases (352, 76%) had the highest prevalence among patients diagnosed with NTM diseases (465/852, 54.6%) with no gender difference. Male patients were older (68.5 years, P = 0.014) with a higher incidence of chronic obstructive pulmonary disease (COPD) (23.6%, P < 0.001) and recurrent cough with phlegm production (51.6%, P = 0.035). In contrast, more female patients had bronchiectasis (50%, P < 0.001) and haemoptysis (37.6%, P = 0.042). Age and COPD were associated with multiple NTM species isolation per patient.

Conclusions

M. abscessus-chelonae group was the commonest NTM species isolated in Singapore. Pulmonary NTM infection has the highest frequency with male and female patients associated with a higher incidence of COPD and bronchiectasis respectively. Age and COPD were associated with multiple NTM species isolation per patient.

Pulmonary nontuberculous mycobacterial infections: presumptive diagnosis based on the international microbiological criteria adopted in the state of São Paulo, Brazil, 2011-2014

Objective:

Pulmonary nontuberculous mycobacterial infections are caused by nontuberculous mycobacteria (NTM), the microbiological diagnosis of which involves the isolation and identification of the same species in at least two sputum samples, one BAL fluid sample, or one lung biopsy sample. The objective of the present study was to determine the frequency at which the various NTM species are identified among selected individuals and in potential cases of pulmonary nontuberculous mycobacterial infection.

Methods:

This was a retrospective analysis of the data on species isolated from respiratory specimens collected from 2,843 individuals between 2011 and 2014. Potential NTM infection cases were identified on the basis of the international microbiological criteria adopted in the state of São Paulo.

Results:

A total of 50 species were identified using the molecular method PCR-restriction enzyme analysis. Samples collected from 1,014 individuals were analyzed in relation to the microbiological criteria, and 448 (44.18%) had a presumptive diagnosis of pulmonary nontuberculous mycobacterial infection, the species identified most frequently being, in descending order, Mycobacterium kansasii, M. abscessus, M. intracellulare, M. avium, and M. szulgai.

Conclusions:

Although various NTM species were identified among the individuals studied, those presumptively identified most frequently on the basis of the microbiological criteria adopted in the state of São Paulo were the ones that are most commonly associated with pulmonary nontuberculous mycobacterial infection worldwide or in specific geographic regions.

High rates of Mycobacterium fortuitum isolation in respiratory samples from Iranian patients with suspected tuberculosis: is it clinically important?

PURPOSE

Although Mycobacterium fortuitum (M. fortuitum) is not an organism rarely isolated from respiratory samples, its clinical importance is still not fully understood, which therefore prompted our current study.

METHODOLOGY

We evaluated respiratory samples from 6800 patients with suspected tuberculosis from May 2014 to May 2016, for the detection of M. fortuitum using phenotypic and genotyping methods.Results/Key findings. Of the 40 patients with M. fortuitum lung disease, 35 had two or more positive culture results. The mean age of these 35 patients was 50.7±18.4 years, and 20 (57.1 %) were men. Sputum (68.6 %), haemoptysis (51.4 %), cough (45.7 %) and gastroesophageal disease (22.9 %) were the major presenting symptoms. Cystic fibrosis, other bacterial lung diseases and lung cancer were the main underlying pulmonary diseases. Five patients (12.5 %) were human immunodeficiency virus (HIV) positive. The most common chest X-ray findings were reticulonodular opacities (53.3 %). Multivariate logistic regression analysis revealed that cigarette smoking history (OR 0.334, 95 % CI 0.125-0.843, P=0.048) and underlying lung disease (OR 0.393, 95 % CI 0.216-0.588, P=0.023) were significant predictors for positive M. fortuitum infection.

CONCLUSION

These results demonstrated the high frequency of M. fortuitum in respiratory samples and that this bacterium causes transient infection or colonization in patients with underlying pulmonary conditions, such as cystic fibrosis and cigarette smoking-induced. Additionally, it appears that infection with M. fortuitum is particularly common and may be important in patients with HIV.

Natural history of Mycobacterium fortuitum pulmonary infection presenting with migratory infiltrates: a case report with microbiological analysis

Background

Presence of Mycobacterium fortuitum in respiratory tracts usually indicates mere colonization or transient infection, whereas true pulmonary infection occurs in patients with gastroesophageal disease. However, little is known about the diagnostic indications for true M. fortuitum pulmonary infection and the natural history of the disease.

Case presentation

A 59-year-old man was referred to our hospital for treatment against M. fortuitum pulmonary infection. Fifteen years before the referral, he underwent total gastrectomy, after which he experienced esophageal reflux symptoms. After the referral, the patient was closely monitored without antimicrobial therapy because of mild symptoms and no pathological evidence of M. fortuitum pulmonary infection. During the observation, chest imaging showed migratory infiltrates. Two years after the referral, his lung biopsy specimen revealed foamy macrophages and multinucleated giant cells, indicating lipoid pneumonia. However, he was continually monitored without any treatment because there was no evidence of nontuberculous mycobacterial infection. Four years after the referral, he developed refractory pneumonia despite receiving adequate antibiotic therapy. After confirmation of granulomatous lesions, multiple antimicrobial therapy for M. fortuitum resulted in a remarkable improvement with no exacerbation for over 5 years. Random amplified polymorphic DNA polymerase chain reaction analysis revealed identical M. fortuitum strains in seven isolates from six sputum and one intestinal fluid specimens obtained during the course of the disease.

Conclusions

We have described a patient with M. fortuitum pulmonary infection who presented with migratory infiltrates. The pathological evidence and microbiological analysis suggested that M. fortuitum pulmonary infection was associated with lipoid pneumonia and chronic exposure to gastrointestinal fluid. Therefore, physicians should carefully monitor patients with M. fortuitum detected from lower respiratory tract specimens and consider antimicrobial therapy for M. fortuitum infection when the patient does not respond to adequate antibiotic therapy against common pneumonia pathogens.

Septicemia and pneumonia due to Mycobacterium fortuitum infection in a patient with extronodal NK/T-cell lymphoma, nasal type: A case report

RATIONALE

Mycobacterium fortuitum (M.fortuitum) is one of the rapidly growing nontuberculous mycobacterium (NTM) that is widespread in the environment. M.fortuitum can cause different types of disease including pulmonary disease, lymphadenitis, cutaneous disease, and disseminated disease. However, the infection presenting as septicemia is exceedingly rare.

PATIENT CONCERNS

A 48-year-old immunocompromised male with extranodal NK/T-cell lymphoma, nasal type was admitted to the hospital because of high fever for 10 days.

DIAGNOSES

The pathogen identified twice in the hemoculture was M.fortuitum, but not in the sputum culture. The chest computed tomographic (CT) scan showed a chronic inflammatory infection.

INTERVENTIONS

The patient was treated with sulfamethoxazole and levofloxacin.

OUTCOMES

The symptom of patient disappeared after the treatment for one week, and near-total absorption of the consolidation in CT after the treatment for one month. He continued the treatment for one year until the last negative hemoculture.

LESSONS

Although the M.fortuitum infection presenting as septicemia is rare, a high suspicion of M.fortuitum is required, particularly in the immunosuppressive patients. Timely and adequate treatment is necessary.

Applying the One Health Concept to Mycobacterial Research - Overcoming Parochialism

Mycobacterial infections remain a public health problem. Historically important, globally ubiquitous and with a wide host range, we are still struggling to control mycobacterial infections in humans and animals. While previous reviews have focused on individual mycobacterial infections in either humans or animals, a comprehensive review of the zoonotic aspect of mycobacteria in the context of the One Health initiative is lacking. With the purpose of providing a concise and comprehensive resource, we have collated literature to address the zoonotic potential of different mycobacterial species and elaborate on the necessity for an inter-sectorial approach to attain a new vision to combat mycobacterial infections.

Mycobacterium fortuitum empyema associated with an indwelling pleural catheter: Case report and review of the literature

Mycobacterium fortuitum is a rapidly growing mycobacterium (RGM) that is an uncommon cause of healthcare-associated infections. The most common infections caused by M. fortuitum include skin, soft tissue, and catheter-related infections. Although occasionally cultured from sputum samples, M. fortuitum is a rare cause of pulmonary disease. We report a case of M. fortuitum empyema associated with an infected pleural catheter and review M. fortuitum pulmonary infections.

Clinical Significance of Nontuberculous Mycobacteria Isolated From Respiratory Specimens in a Chinese Tuberculosis Tertiary Care Center

The clinical relevance of non-tuberculous mycobacteria (NTM) has been reported to be different dramatically by species or by regions, however, no such evaluation has been performed in China.A retrospective study was performed in Beijing Chest Hospital. All the NTM strains isolated from respiratory specimens in the past 5 years, and patients' clinical records (symptoms and radiographic information etc.) were investigated. The clinical relevance was evaluated according to the criteria recommended by the American Thoracic society. Totally 232 NTM strains were recruited, among them, M. intracellulare was the dominant species (40.5%), followed by M. abscessus (28.4%). 109 patients, with 185 total isolates, had full clinical records available for review. 84.4% (38/45), 85.7% (24/28%) and 63.6% (7/11) of patients with isolation of M. intracellulare, M. abscessus and M. kansasii, respectively, were categorized as definite NTM disease. Whereas all the 10 patients with isolation of M. gordonae were defined as unlikely NTM disease. The majority of NTMs isolates yielded from respiratory specimens in Beijing Chest Hospital were clinically significant, and M. intracellulare and M. abscessus was the dominated species of NTM lung disease. NTM lung infections demonstrated some specific chest radiograph characteristics.

The looming tide of nontuberculous mycobacterial infections in Portugal and Brazil

Nontuberculous mycobacteria (NTM) are widely disseminated in the environment and an emerging cause of infectious diseases worldwide. Their remarkable natural resistance to disinfectants and antibiotics and an ability to survive under low-nutrient conditions allows NTM to colonize and persist in man-made environments such as household and hospital water distribution systems. This overlap between human and NTM environments afforded new opportunities for human exposure, and for expression of their often neglected and underestimated pathogenic potential. Some risk factors predisposing to NTM disease have been identified and are mainly associated with immune fragilities of the human host. However, infections in apparently immunocompetent persons are also increasingly reported. The purpose of this review is to bring attention to this emerging health problem in Portugal and Brazil and to emphasize the urgent need for increased surveillance and more comprehensive epidemiological data in both countries, where such information is scarce and seriously thwarts the adoption of proper preventive strategies and therapeutic options.

Nontuberculous mycobacterial pulmonary infection in patients with idiopathic interstitial pneumonias: comparison with patients without idiopathic interstitial pneumonias

OBJECTIVE

The aim of this study was to describe computed tomography (CT) findings of nontuberculous mycobacterial (NTM) pulmonary infection in patients with idiopathic interstitial pneumonias (IIP) in comparison with those in patients without IIP.

METHODS

From November 2001 to October 2012, 810 patients in the NTM registry were retrospectively reviewed. Among them, 42 patients (mean age, 69.7 years; 32 men and 10 women) who were diagnosed as having IIP by either histological or radioclinical criteria were included in our study. Eighty-two age- and sex-matched immunocompetent patients with NTM pulmonary infection and without IIP were selected as the control group. Medical records and CT scans were reviewed. Formal radiologic reports obtained before diagnosis of NTM infection were also reviewed.

RESULTS

Lobar/segmental consolidation (85.7%) was the most common CT finding in the IIP group, whereas branching centrilobular nodules (95.1%), traction bronchiectasis (79.3%), and volume decrease (58.5%) were common in the control group. Frequencies of these findings were significantly different between the 2 groups (P < 0.001). Most of consolidations were associated with cavity (83.3%) without dominant zonal distribution. Pneumonia or fungal infection (n = 20) was the most common radiologic diagnosis in the IIP group.

CONCLUSIONS

The NTM pulmonary infection in IIP patients is characterized as lobar/segmental consolidation with/without cavity, different to immunocompetent patients without IIP, and can mimic other diseases especially bacterial/fungal infection.

Mycobacterium abscessus subsp abscessus lung disease: 'trouble ahead, trouble behind…'

Mycobacterium abscessus subsp abscessus is the most common respiratory pathogen among the rapidly growing non-tuberculous mycobacteria (NTM) and is also the most feared due to its well-deserved reputation for being refractory to antibiotic therapy. M. abscessus subsp abscessus has multiple innate antibiotic resistance mechanisms, but the most important one described so far is an inducible erythromycin methylase (erm) gene. M. abscessus subsp abscessus isolates may appear macrolide susceptible on initial in vitro testing but become macrolide resistant after exposure to macrolide. It is therefore very important to test clinically significant M. abscessus subsp abscessus isolates for erm gene activity. Remarkably, controversy still exists about the taxonomy and nomenclature of M. abscessus subspecies including subsp abscessus, subsp massiliense and subsp bolletii. Identification of these subspecies is not moot as M. abscessus subsp massiliense does not have an active erm gene resulting in both in vitro and in vivo susceptibility to macrolide. It is imperative from the clinician's perspective that mycobacterial laboratories correctly and rapidly identify M. abscessus to the subspecies level. Unfortunately, there are no reliably or predictably effective treatment regimens for M. abscessus subsp abscessus and better, more effective antimicrobial agents are badly needed. Surgical resection of involved lung tissue as an adjunct to antibiotic therapy is beneficial in selected patients but cannot be broadly applied. Overall, M. abscessus subsp abscessus remains a formidable respiratory mycobacterial pathogen, one that we are only beginning to understand microbiologically and one that as yet consistently evades our best efforts at successful therapeutic outcomes.

‘trouble ahead, trouble behind, and you know that notion just crossed my mind’.

Casey Jones, Grateful Dead (1970)

Distribution of nontuberculous mycobacteria by multigene sequence-based typing and clinical significance of isolated strains

Species identification of nontuberculous mycobacteria (NTM) is challenging due to the increasing number of identified NTM species and the lack of standardized testing strategies. The objectives of this study were to investigate the distribution of NTM species recovered from respiratory specimens by multigene sequence-based typing and to evaluate the clinical significance of identified species. Two hundred thirty-two consecutive clinical NTM isolates were subjected to sequencing of multiple genes, including hsp65, rpoB, and 16S-23S rRNA internal transcribed spacer (ITS) sequence. In addition, clinical data from all patients whose specimens had NTM isolates were analyzed to examine clinical virulence and treatment history. Eighteen strains from 227 isolates from 169 patients were successfully identified at the species level by multigene sequence-based typing. Mycobacterium avium complex and M. abscessus complex made up the majority of isolated NTM (88%; 199/227), followed by M. fortuitum complex (4%; 10/227). The pathogenic potential of NTM differs enormously by species, and M. avium complex and M. abscessus complex revealed especially high levels of virulence compared with findings for other NTM species. The results from our work support M. avium complex and M. abscessus complex being the most common NTM species with highly pathogenic potential isolated from clinical respiratory specimens and could be a good resource for molecular epidemiology of NTM species in South Korea.

Pulmonary Mycobacterium fortuitum infection with cervical lymphadenitis in a patient carrying autoantibodies to interferon-γ

A 74-year-old woman was referred to our hospital for an evaluation of unidentified pneumonia. She gradually developed a high-grade fever with a growing infiltrative shadow on chest CT and an enlarging bilateral cervical mass. She was diagnosed with a pulmonary Mycobacterium fortuitum (M. fortuitum) infection with cervical lymphadenitis based on the results of an open biopsy of the cervical lymph node. While the patient's clinical condition resolved almost completely after treatment with multiple antibiotics, neutralizing autoantibodies to interferon-gamma (IFN-γ) were identified in her serum. The progression of disseminated M. fortuitum infection in immunocompetent patients may be affected by the presence of autoantibodies to IFN-γ.

Nontuberculous mycobacteria in guadeloupe, martinique, and French Guiana from 1994 to 2012

Nontuberculous mycobacteria (NTM) are ubiquitous environmental organisms able to cause severe opportunistic human infections. Their distribution patterns are subject to geographical variations. This study describes their isolation frequencies from clinical specimen in the three French overseas departments of the Americas, namely, Guadeloupe, Martinique, and French Guiana during 1994-2012. A total of 651 strains from as many patients (one isolate per species per patient) were analysed regarding regional isolation patterns and potential pattern changes over time. The Mycobacterium avium complex was the most common group of NTM in Guadeloupe and French Guiana. In Martinique it was the second most common after the rapidly growing mycobacteria. M. fortuitum was the most commonly isolated species in all three departments. Some species (M. kansasii, M. xenopi, and M. terrae complex) displayed a clear regional preference. Furthermore a change in isolation frequency was observed for M. intracellulare (increase) and M. kansasii (decrease) in Guadeloupe. In conclusion, marked regional differences in isolation frequencies of NTM species were observed in the study area. Results are discussed in context of variables such as study populations, risk factors, methodology employed, isolation from pulmonary versus sterile isolation sites (blood, urine, and CSF), and in vitro drug-susceptibility patterns.

Mycobacterial pulmonary infections in patients with idiopathic pulmonary fibrosis

Patients with idiopathic pulmonary fibrosis (IPF) have an increased risk for developing tuberculosis (TB). However, no studies have been reported regarding the development of nontuberculous mycobacterium (NTM) lung disease (NTMLD). We reviewed 795 patients with IPF from five university hospitals who were diagnosed by histological or radio-clinical criteria. In the 795 patients with IPF, pulmonary infections with mycobacterium tuberculosis (MTB) and NTM were found in 35 (4.4%) and 16 patients (2.0%), respectively, which was a higher frequency than that found in the general population. TB was more common in patients treated with immunosuppressants than in those who did not receive immunosuppressants (2.6% vs 1.4%, P = 0.12). Among the IPF patients who had mycobacterial infections,immunosuppressant users developed TB or NTMLD within 1 yr after treatment with immunosuppressants,while those occurred later than 2 yr after diagnosis of IPF in the subjects that did not receive immunosuppressants. Among 51 IPF patients who had mycobacterial infections, 9 (18%) died during follow-up. Of these, three died due to progression of pulmonary tuberculosis. TB and NTMLD is relatively common in patients with IPF in Korea and may be fatal in some groups. Careful evaluation of TB and NTMLD is necessary not only for immunosuppressant users, but also for nonusers with IPF.

Failure to recognize nontuberculous mycobacteria leads to misdiagnosis of chronic pulmonary tuberculosis

Background

Nontuberculous mycobacterial (NTM) infections cause morbidity worldwide. They are difficult to diagnose in resource-limited regions, and most patients receive empiric treatment for tuberculosis (TB). Our objective here is to evaluate the potential impact of NTM diseases among patients treated presumptively for tuberculosis in Mali.

Methods

We re-evaluated sputum specimens among patients newly diagnosed with TB (naïve) and those previously treated for TB disease (chronic cases). Sputum microscopy, culture and Mycobacterium tuberculosis drug susceptibility testing were performed. Identification of strains was performed using molecular probes or sequencing of secA1 and/or 16S rRNA genes.

Results

Of 142 patients enrolled, 61 (43%) were clinically classified as chronic cases and 17 (12%) were infected with NTM. Eleven of the 142 (8%) patients had NTM disease alone (8 M. avium, 2 M. simiae and 1 M. palustre). All these 11 were from the chronic TB group, comprising 11/61 (18%) of that group and all were identified as candidates for second line treatment. The remaining 6/17 (35.30%) NTM infected patients had coinfection with M. tuberculosis and all 6 were from the TB treatment naïve group. These 6 were candidates for the standard first line treatment regimen of TB. M. avium was identified in 11 of the 142 (8%) patients, only 3/11 (27.27%) of whom were HIV positive.

Conclusions

NTM infections should be considered a cause of morbidity in TB endemic environments especially when managing chronic TB cases to limit morbidity and provide appropriate treatment.

Bronchiectasis and nontuberculous mycobacterial disease

Over the last 30 years it has become increasingly clear that nontuberculous mycobacterial (NTM) lung infections and bronchiectasis are closely related disorders. Although incontrovertible proof is lacking, there is a growing consensus of opinion that NTM lung disease characterized by nodules and bronchiectasis (nodular/bronchiectatic NTM lung disease) may be a consequence of preexisting bronchiectasis that predisposes to NTM infection and disease. To use published diagnostic guidelines effectively, physicians must become familiar with the disease-causing potential of individual NTM species. Essentially all NTM patients have bronchiectasis, so optimal overall patient management requires successful therapeutic strategies for both NTM infection and bronchiectasis.

Clinical significance and antibiotic susceptibilities of nontuberculous mycobacteria from patients in Crete, Greece

AIM

To describe the clinical significance and antibiotic susceptibilities of nontuberculous mycobacteria (NTM) isolated from patients in Crete, Greece between January 2000 and December 2009.

PATIENTS & METHODS

NTM identification was performed using conventional bacteriological methods and confirmed by molecular characterization with commercially available assays. Rare and novel species were identified by sequencing of the 16SrRNA and of the hsp65 genes. Antibiotic susceptibility testing was performed by E-test. Rapidly growing (RGM) and slowly growing (SGM) NTM were tested against 14 antimicrobials, including nine common ones, except for Mycobacterium avium and Mycobacterium intracellulare (MAC) complex isolates that were tested only against azithromycin, clarithromycin, linezolid and moxifloxacin.

RESULTS

During the study period, 290 positive samples for NTM were recovered from 207 patients. Among the positive samples, 150 were identified as SGM and 57 as RGM. Overall, 50 patients met American Thoracic Society criteria for disease due to NTM, 42 by SGM and eight by RGM. Risk factors in patients with NTM disease were underlying lung diseases, mainly chronic obstructive pulmonary disease and asthma, smoking, rheumatoid arthritis, AIDS, alcohol or drug abuse, malignancies and bronchiectasis. The most common disease-causing species were the MAC complex (n = 25) followed by Mycobacterium kansasii (n = 10). Amikacin was the most active drug for RGM with 100% susceptibility. Macrolides were very active against isolates of the MAC complex, while tigecycline had excellent activity in vitro against RGM. M. kansasii was the most susceptible NTM species in vitro.

CONCLUSION

Our study is the first to describe the clinical significance, risk factors and susceptibility patterns of NTM isolates in a Greek population.

[Diagnosis and treatment of atypical mycobacterial infections of the respiratory tract]

INTRODUCTION

Non tuberculous mycobacteria (NTM), unlike tuberculous mycobacteria, are not strictly human pathogens. The diagnosis of infection and the choice of treatment remain difficult.

BACKGROUND

Evidence of a NTM in a pulmonary sample is not synonymous with infection. The diagnosis depends on the association of clinical, radiological and microbiological factors. If a NTM is isolated from a respiratory sample, the probability of infection depends on the species. The main NTMs responsible for pulmonary infection in France are Mycobacterium avium intracellulare, Mycobacterium xenopi, Mycobacterium kansasi and Mycobacterium abscessus. Their management is difficult and poorly understood. Treatment is well established for M. avium intracellulare and M. kansasii, with combinations of clarithromycin-rifampicin-ethambutol and isoniazid-rifampicin-ethambutol respectively. For M. xenopi, the optimal treatment is not known and a combination of clarithromycin-rifampicin-ethambutol, with moxifloxacin as an alternative, is currently recommended. In general, treatment is prolonged and often associated with problems of tolerance.

VIEWPOINT AND CONCLUSION

The management of NTM infection, taking into account of the increase in patients "at risk", is an important issue. Further studies are needed to improve the criteria for infection and to find the optimal therapeutic combinations.

High-resolution CT of complications of idiopathic fibrotic lung disease

Idiopathic pulmonary fibrosis (IPF) has a more variable clinical course than has been traditionally recognised. Many patients will remain stable over time while others experience relatively rapid deterioration. The prognosis and clinical course of patients with other fibrosing lung diseases is also variable. A number of conditions may complicate the clinical course of the idiopathic fibrosing lung diseases, which results in morbidity and mortality, but also represents potentially treatable causes of worsening symptoms. Infection and malignancy have a long-recognised association with IPF while other conditions, particularly pulmonary hypertension and acute exacerbation of IPF, are being increasingly recognised in this patient population. Many of these patients have serial high-resolution CT (HRCT) examinations that may demonstrate one or more of these supervening conditions. In this article we review the more common conditions that may complicate the course of idiopathic fibrosing lung disease with an emphasis on the HRCT appearance, which the reporting radiologist should be aware of.

Application of a broad-range resequencing array for detection of pathogens in desert dust samples from Kuwait and Iraq

A significant percentage of the human population is exposed to high levels of naturally occurring airborne dusts. Although the link between airborne particulate inhalation and a variety of respiratory diseases has long been established, little is known about the pathogenic role of the microbial component of the dust. In this study, we applied highly multiplexed PCR and a high-density resequencing microarray (RPM-TEI version 1.0) to screen samples of fine topsoil particles and airborne dust collected in 19 locations in Iraq and Kuwait for the presence of a broad range of human pathogens. The results indicated the presence of potential human pathogens, including Mycobacterium, Brucella, Coxiella burnetii, Clostridium perfringens, and Bacillus. The presence of Coxiella burnetii, a highly infectious potential biowarfare agent, was confirmed and detected in additional samples by use of a more sensitive technique (real-time PCR), indicating a high prevalence of this organism in the analyzed samples. The detection of potentially viable pathogens in breathable dusts from arid regions of Iraq and Kuwait underscores the importance of further study of these environments.

Successful treatment of Mycobacterium celatum pulmonary disease in an immunocompetent patient using antimicobacterial chemotherapy and combined pulmonary resection

Mycobacterium celatum is a nontuberculous mycobacterium that rarely causes pulmonary disease in immunocompetent subjects. We describe the successful treatment of M. celatum lung disease with antimicobacterial chemotherapy and combined pulmonary resection. A 33-year-old woman was referred to our hospital with a 3-month history of a productive cough. Her medical history included pulmonary tuberculosis 14 years earlier. Her chest X-ray revealed a large cavitary lesion in the left upper lobe. The sputum smear was positive for acid-fast bacilli, and M. celatum was subsequently identified in more than three sputum cultures, using molecular methods. After 1 year of therapy with clarithromycin, ethambutol, and ciprofloxacin, the patient underwent a pulmonary resection for a persistent cavitary lesion. The patient was considered cured after receiving 12 months of postoperative antimycobacterial chemotherapy. There has been no recurrence of disease for 18 months after treatment completion. In summary, M. celatum is an infrequent cause of potentially treatable pulmonary disease in immunocompetent subjects. Patients with M. celatum pulmonary disease who can tolerate resectional surgery might be considered for surgery, especially in cases of persistent cavitary lesions despite antimycobacterial chemotherapy.

Lung cancer in HIV-infected patients: the experience of an urban clinic

BACKGROUND

Lung cancer is one of the most common non-AIDS-defining malignancies among HIV-infected patients. Recent studies suggest that lung cancer risk is 3 to 4 times higher in HIV-infected patients than in uninfected persons after adjusting for other factors such as smoking intensity and duration.

METHODS

A retrospective chart review (2002-2009) was conducted in our institution. An abstraction form was used to compile data that included demographics, T-cell count, and viral loads before and at the time of diagnosis, comordibities, smoking, and use of alcohol and drugs.

RESULTS

A total of 16 patients were found. Of these, 11 (69%) patients were male and 5 (31%) female. The average age at diagnosis was 49 years (range 36-54). The Majority of patients were African American (90%). Their average CD4 counts before and at the time of diagnoses were 241 and 211 cells/mm( 3), respectively. Their viral loads before and at the time of diagnosis ranged from <48 to 437 000 and <48 to 590 760 copies/mL, respectively. Adenocarcinoma was found in 67% of cases. The majority of cases (85%) were detected at advanced stages (IIIB or IV). Smoking was found in 100% of cases (average of 15-20 pack/year history), alcohol use in 70% of cases, and drug abuse in 50%.

CONCLUSIONS

Lung cancer is very common in HIV-infected populations. It tends to occur at a young age, and it is usually diagnosed at very advanced stages (IIIB or IV). The main risk factors found in our study were extensive smoking history, young age, male sex, and potentially prolonged immunosuppression. Based on these results, an attempt to construct a high-risk group index might not be appropriate due to the limited number of cases studied and the need for further evaluation of the length of immunosuppression and the real impact of HIV RNA viral load in the development of lung cancer.