Pulmonary and disseminated infection due to Mycobacterium kansasii: a decade of experience

The Other Nontuberculous Mycobacteria: Clinical Aspects of Lung Disease Caused by Less Common Slowly Growing Nontuberculous Mycobacteria Species

Slowly growing nontuberculous mycobacteria (NTM) comprise a diverse group of environmental organisms, many of which are important human pathogens. The most common and well-known member of this group is Mycobacterium avium, the leading cause of nontuberculous mycobacterial pulmonary disease (NTM-PD) globally. This review focuses on the less common, but notable, species of slowly growing NTM with respect to lung disease. To prepare this article, literature searches were performed using each species name as the key word. Society guidelines were consulted, and relevant articles also were identified through the reference lists of key articles. The specific organisms highlighted include Mycobacterium kansasii, Mycobacterium xenopi, Mycobacterium malmoense, Mycobacterium simiae, and Mycobacterium szulgai. Although these organisms are closely related, they have distinct epidemiologic features and behavior as pathogens. Therefore, the diagnosis and management of NTM-PD require a nuanced approach that takes into consideration the unique characteristics of each species. There is limited evidence to inform the optimal treatment of NTM-PD. Antimicrobial therapy is often challenging because of the presence of drug resistance and few antibiotic options. Regimen selection should generally be guided by drug susceptibility testing, although the correlation between clinical outcomes and in vitro susceptibility thresholds has not been defined for most species.

Huge cutaneous abscess and severe symptomatic hypercalcaemia secondary to Mycobacterium kansasii infection in an immunocompetent patient

Mycobacterium kansasii is among the most common non-tuberculous mycobacteria causing human infections. Apart from pulmonary infection, the most common infection caused by M. kansasii is skin and soft tissue infection, and it is very rare in immunocompetent people. In this report, we present a case of a huge cutaneous abscess caused by M. kansasii A 63-year-old man living in Bangkok presented with progressive pain at the left lateral chest wall for 3 weeks and altered mentation for a few days. Examination revealed a non-tender fluctuated cutaneous mass 20×10 cm in size. An aspiration of the mass yielded 50 mL pus with many positive acid-fast bacilli. Mycobacterial PCR was positive for M. kansasii with culture confirmation. There was severe hypercalcaemia. The treatment included surgical drainage, and medical treatment consisted of isoniazid, rifampicin, ethambutol and levofloxacin, along with adequate hydration and calcitonin for hypercalcaemia. The patient gradually improved and was discharged 12 days after hospitalisation.

Mycobacterial Evolution Intersects With Host Tolerance

Over the past 200 years, tuberculosis (TB) has caused more deaths than any other infectious disease, likely infecting more people than it has at any other time in human history. Mycobacterium tuberculosis (Mtb), the etiologic agent of TB, is an obligate human pathogen that has evolved through the millennia to become an archetypal human-adapted pathogen. This review focuses on the evolutionary framework by which Mtb emerged as a specialized human pathogen and applies this perspective to the emergence of specific lineages that drive global TB burden. We consider how evolutionary pressures, including transmission dynamics, host tolerance, and human population patterns, may have shaped the evolution of diverse mycobacterial genomes.

Mycobacterium kansasii osteomyelitis - a masquerading disease

Introduction

Non-tuberculous mycobacteria (NTM) are environmental bacteria capable of causing an opportunistic myriad of infections. Mycobacterium kansasii, one such NTM, is responsible for causing pulmonary disease in immunocompromised patients. Rare extrapulmonary manifestations such as lymphadenitis, osteoarticular manifestations, and skin and soft tissue infections are also observed.

Case presentation

Here, we report an unusual case of sternoclavicular joint and elbow joint infection with M. kansasii in a relatively immunocompetent patient. Histopathology did not show classic granulomas and mycobacterial infection was not initially considered as a possibility. However repeat biopsies were sent for mycobacterial cultures which then grew M. kansasii.

Conclusion

Diagnosis of M. kansasii in such cases can be difficult and culture-positive results may not necessarily imply positive diagnosis as they can be environmental contaminants. Furthermore, M. kansasii can cause infections without the characteristic granuloma formation, which can further complicate tissue diagnosis. This underlines the importance of ensuring that tissue samples obtained are cultured for mycobacteria.

Mycobacterium kansasii

The incidence of Mycobacterium kansasii varies widely over time and by region, but this organism remains one of the most clinically relevant isolated species of nontuberculous mycobacteria. In contrast to other common nontuberculous mycobacteria, M. kansasii is infrequently isolated from natural water sources or soil. The major reservoir appears to be tap water. Infection is likely acquired through the aerosol route, with low infectivity in regions of endemicity. Human-to-human transmission is thought not to occur. Clinical syndromes and radiological findings of M. kansasii infection are mostly indistinguishable from that of Mycobacterium tuberculosis, thus requiring microbiological confirmation. Disseminated disease is uncommon in HIV-negative patients and usually associated with severe immunosuppression. The majority of patients with M. kansasii pulmonary disease have underlying pulmonary comorbidities, such as smoking, chronic obstructive pulmonary disease, bronchiectasis, and prior or concurrent M. tuberculosis infection. Surveys in Great Britain, however, noted higher rates, with 8 to 9% of M. kansasii infections presenting with extrapulmonary disease. Common sites of extrapulmonary disease include the lymph nodes, skin, and musculoskeletal and genitourinary systems. The specificity of gamma interferon release assays (IGRAs) for M. tuberculosis may be reduced by M. kansasii infection, as M. kansasii encodes CFP-10 and ESAT-6, two antigens targeted by IGRAs. A study conducted to evaluate the therapy in rifampin-resistant disease found that patients with acquired rifampin resistance were treated with daily high-dose ethambutol, isoniazid, sulfamethoxazole, and pyridoxine combined with aminoglycoside therapy. Given the potential toxicities, particularly with aminoglycoside therapy, clarithromycin and/or moxifloxacin therapy could be considered as alternatives.

Complete Genome Sequences of Mycobacterium kansasii Strains Isolated from Rhesus Macaques

Mycobacterium kansasii is a nontuberculous mycobacterium. It causes opportunistic infections with pulmonary and extrapulmonary manifestations. We report here the complete genome sequences of two M. kansasii strains isolated from rhesus macaques. We performed genome comparisons with human and environmental isolates of M. kansasii to assess the genomic diversity of this species.

Mediastinal and Disseminated Mycobacterium kansasii Disease in GATA2 Deficiency

RATIONALE

Mycobacterium kansasii usually causes chronic pulmonary infections in immunocompetent patients. In contrast, disseminated M. kansasii disease is commonly associated with advanced human immunodeficiency virus infection, but is reported infrequently in other immunocompromised patients.

OBJECTIVES

To identify common clinical manifestations and potential risk factors for M. kansasii infection in patients with GATA2 deficiency.

METHODS

We reviewed M. kansasii disease associated with GATA2 deficiency at one institution and disease associated with primary and other immunodeficiencies reported in the literature.

MEASUREMENTS AND MAIN RESULTS

Nine patients with GATA2 deficiency developed M. kansasii infections. Six patients developed disseminated disease. All patients presented with significant mediastinal lymphadenopathy or abscesses. Seven patients had pulmonary risk factors, including six smokers. The majority of patients had low numbers of neutrophils, monocytes, B cells, CD4+ T cells, and natural killer cells. Other conditions associated with disseminated M. kansasii disease were thymic disorders and IFN-γ/IL-12 defects.

CONCLUSIONS

Disseminated M. kansasii disease involving mediastinal lymph nodes is surprisingly common in GATA2 deficiency, but also occurs in defects of IFN-γ synthesis and response. Disseminated M. kansasii should be considered a marker indicating a need to evaluate for immunodeficiency syndromes.

Isolated Mycobacterium kansasii wound infection and Osteomyelitis in an immunocompetent patient

Mycobacterium kansasii is a slow growing acid-fast non-tuberculosis mycobacterium. It most commonly causes pulmonary disease with tuberculosis-like manifestations. Mycobacterium kansasii-induced skin and soft tissue infections (SSTIs) are very uncommon, especially in the absence of obvious risk factors. In this report, we present a rare case of M. kansasii-associated SSTI complicated by tendonitis and osteomyelitis in an immunocompetent patient. This case highlights the importance of considering non-tuberculosis mycobacteria while investigating chronic, relapsing, non-healing SSTIs and osteomyelitis. Proper pharmacotherapy, along with surgical debridement, is the optimal management to avoid relapse and the production of resistant species.

MKAN27435 is required for the biosynthesis of higher subclasses of lipooligosaccharides in Mycobacterium kansasii

Lipooligosaccharides are glycolipids found in the cell wall of many mycobacterial species including the opportunistic pathogen Mycobacterium kansasii. The genome of M. kansasii ATCC12478 contains a cluster with genes orthologous to Mycobacterium marinum LOS biosynthesis genes. To initiate a genetic dissection of this cluster and demonstrate its role in LOS biosynthesis in M. kansasii, we chose MKAN27435, a gene encoding a putative glycosyltransferase. Using Specialized Transduction, a phage-based gene knockout tool previously used to generate null mutants in other mycobacteria, we generated a MKAN27435 null mutant. The mutant strain was found to be defective in the biosynthesis of higher LOS subspecies, viz LOS-IV, LOS-V, LOS-VI and LOS-VII. Additionally, a range of low abundance species were detected in the mutant strain and mass spectroscopic analysis indicated that these were shunt products generated from LOS-III by the addition of up to six molecules of a pentose.

Insights on the emergence of Mycobacterium tuberculosis from the analysis of Mycobacterium kansasii

By phylogenetic analysis, Mycobacterium kansasii is closely related to Mycobacterium tuberculosis. Yet, although both organisms cause pulmonary disease, M. tuberculosis is a global health menace, whereas M. kansasii is an opportunistic pathogen. To illuminate the differences between these organisms, we have sequenced the genome of M. kansasii ATCC 12478 and its plasmid (pMK12478) and conducted side-by-side in vitro and in vivo investigations of these two organisms. The M. kansasii genome is 6,432,277 bp, more than 2 Mb longer than that of M. tuberculosis H37Rv, and the plasmid contains 144,951 bp. Pairwise comparisons reveal conserved and discordant genes and genomic regions. A notable example of genomic conservation is the virulence locus ESX-1, which is intact and functional in the low-virulence M. kansasii, potentially mediating phagosomal disruption. Differences between these organisms include a decreased predicted metabolic capacity, an increased proportion of toxin–antitoxin genes, and the acquisition of M. tuberculosis-specific genes in the pathogen since their common ancestor. Consistent with their distinct epidemiologic profiles, following infection of C57BL/6 mice, M. kansasii counts increased by less than 10-fold over 6 weeks, whereas M. tuberculosis counts increased by over 10,000-fold in just 3 weeks. Together, these data suggest that M. kansasii can serve as an image of the environmental ancestor of M. tuberculosis before its emergence as a professional pathogen, and can be used as a model organism to study the switch from an environmental opportunistic pathogen to a professional host-restricted pathogen.

Mai infection simulating metastatic breast cancer

We represent a case of an asymptomatic female who was found to have a mass in the right breast which confirmed an invasive ductal carcinoma by core biopsy. After 3 months of completion of chemo-radiotherapy, the patient remained totally asymptomatic. However, positron emission tomography scan showed four hypermetabolic lesions in the left lung thought to be consistent with metastatic disease. Standard uptake value ranged between 3.86 and 6; the results were consistent with metastatic breast cancer, so wedge resection was performed. Caseating granulomatous inflammation with necrosis was reported. Ultimately culture revealed Mycobacterium avium intracellulare infection. The lesions resolved completely after a course of antibiotics.

A case of wrist tenosynovitis caused by Mycobacterium kansasii in a renal transplant recipient

Mycobacterial infection in an organ transplant recipient is a diagnostic and therapeutic challenge. Diagnosis is often delayed, resulting in significant morbidity. Anti-microbial chemotherapy needs careful selection to prevent potentially significant complications, such as organ rejection and dose-related toxicities. We present the case of a 61-year-old Caucasian male kidney transplant recipient with chronic tenosynovitis of the left wrist. Histological findings of the synovial biopsy revealed multinucleated giant cell epithelioid granuloma. Culture of synovial fluid grew Mycobacterium kansasii. Treatment with rifampicin, ethambutol, and clarithromycin proved curative, but the patient developed irreversible ethambutol-related optic neuritis.

Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria

Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria.

Activation of an NLRP3 inflammasome restricts Mycobacterium kansasii infection

Mycobacterium kansasii has emerged as an important nontuberculous mycobacterium pathogen, whose incidence and prevalence have been increasing in the last decade. M. kansasii can cause pulmonary tuberculosis clinically and radiographically indistinguishable from that caused by Mycobacterium tuberculosis infection. Unlike the widely-studied M. tuberculosis, little is known about the innate immune response against M. kansasii infection. Although inflammasome activation plays an important role in host defense against bacterial infection, its role against atypical mycobacteria remains poorly understood. In this report, the role of inflammasome activity in THP-1 macrophages against M. kansasii infection was studied. Results indicated that viable, but not heat-killed, M. kansasii induced caspase-1-dependent IL-1β secretion in macrophages. The underlying mechanism was found to be through activation of an inflammasome containing the NLR (Nod-like receptor) family member NLRP3 and the adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD). Further, potassium efflux, lysosomal acidification, ROS production and cathepsin B release played a role in M. kansasii-induced inflammasome activation. Finally, the secreted IL-1β derived from caspase-1 activation was shown to restrict intracellular M. kansasii. These findings demonstrate a biological role for the NLRP3 inflammasome in host defense against M. kansasii.

Nontuberculous mycobacterial lung diseases

Nontuberculous mycobacteria (NTM) are generally hardy, ubiquitous environmental bacteria that vary in geographic distribution and pulmonary pathogenicity. Relatively few of the more than 115 species of NTM have been associated with lung disease. Diagnosis of disease due to NTM relies on a combination of clinical, imaging, and microbiologic data. Because NTM may present as acid-fast bacilli in respiratory secretions of patients with clinical and radiologic features that mimic tuberculosis, laboratory discrimination of NTM from Mycobacterium tuberculosis is a priority. This discrimination is now often rapidly achievable using molecular techniques, although some tests have limited sensitivity. NTM species have different antibiotic response patterns, and success with medical treatment alone varies. Macrolides are an essential component of therapy for many species but must be combined with other drugs.

Disseminated Mycobacterium kansasii infection associated with skin lesions: a case report and comprehensive review of the literature

Mycobacteruim kansasii occasionally causes disseminated infection with poor outcome in immunocompromised patients. We report the first case of disseminated M. kansasii infection associated with multiple skin lesions in a 48-yr-old male with myelodysplastic syndrome. The patient continuously had taken glucocorticoid during 21 months and had multiple skin lesions developed before 9 months without complete resolution until admission. Skin and mediastinoscopic paratracheal lymph node (LN) biopsies showed necrotizing granuloma with many acid-fast bacilli. M. kansasii was cultured from skin, sputum, and paratracheal LNs. The patient had been treated successfully with isoniazid, rifampin, ethmabutol, and clarithromycin, but died due to small bowel obstruction. Our case emphasizes that chronic skin lesions can lead to severe, disseminated M. kansasii infection in an immunocompromised patient. All available cases of disseminated M. kansasii infection in non HIV-infected patients reported since 1953 are comprehensively reviewed.

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.

Differentiation of Mycobacterium kansasii infection from Mycobacterium tuberculosis infection: comparison of clinical features, radiological appearance, and outcome

This retrospective study sought to systematically identify clinical and radiological features differentiating Mycobacterium kansasii from Mycobacterium tuberculosis infection. The sample included matched patients with a culture-positive diagnosis of M. tuberculosis infection (n = 121) or M. kansasii infection (n = 62) derived from the databases of two tuberculosis centers. Data on patient background and clinical features were collected, and chest radiographs were analyzed. Sixty percent of the M. kansasii group were native Israelis compared to 15% of the M. tuberculosis group (p = 0.0001). M. tuberculosis infection was associated with a higher rate of human immunodeficiency virus (HIV) infection (p = 0.03) and M. kansasii infection with a higher rate of lung disease (p = 0.0001). M. tuberculosis infection was characterized by a higher likelihood of bilateral disease (p = 0.005), pleural effusions, and lymphadenopathy (p = 0.006 and p = 0.001, respectively). There were ten deaths, all in the M. tuberculosis group. On multivariate logistic regression, the presence of chronic obstructive pulmonary disease and associated lung disease were significant predictors of M. kansasii infection. The findings show that there are group differences between the clinical features of the two infections. In the setting of pulmonary mycobacterial infection, the presence of coinfection with HIV, bilateral disease, pleural effusion, and lymphadenopathy make M. kansasii infection very unlikely.

Septic arthritis caused by Mycobacterium kansasii in a prosthetic knee joint

Mycobacterium kansasii is a relatively common cause of nontuberculous mycobacterial pulmonary infection. Septic arthritis caused by Mycobacterium kansasii, on the other hand, is rare. Reported here for the first time is the case of an 82-year-old patient with an infection of a prosthetic knee joint with Mycobacterium kansasii.

Pulmonary Mycobacterium kansasii Infection in Israel, 1999–2004

BACKGROUND

Mycobacterium kansasii infection is one of the most common causes of nontuberculous mycobacterial lung disease in world. However, little is known about its background characteristics or drug sensitivity in nonendemic areas.

DESIGN

We assessed the clinical features, radiologic findings, and drug sensitivity associated with M kansasii infection in Israel.

METHODS

Patients with a culture-positive diagnosis of M kansasii infection between April 1999 and April 2004 were identified from a clinic database of tuberculosis centers. Mycobacterial cultures were performed with standard methods. Data on patient background and clinical features were collected from the medical files.

RESULTS

Mean age (+/- SD) of the 56 patients was 58 +/- 18 years, and 64% were men; 59% had associated lung disease. Fifteen percent were receiving immunosuppressive medications. None had HIV infection. Systemic comorbid diseases were noted in 27%. The most common clinical presentations were chest pain, cough, hemoptysis, fever, and night sweats. Cavitation was noted only in 54%. Older patients had more noncavitary disease than younger patients (p = 0.01, r = 0.35). Lower-lobe predominance was very rare (4%). None of the patients presented with pleural effusion or lymphadenopathy. Only seven patients (11%) underwent bronchoscopy for diagnosis. M kansasii isolates showed the highest sensitivity to rifampin, ethambutol, clarithromycin, and ofloxacin, and the highest resistance to ciprofloxacin and capreomycin. The mean duration of treatment was 21 +/- 7.2 months. There were no disease-related deaths.

CONCLUSIONS

M kansasii disease in Israel has no association with HIV, more systemic comorbid diseases and associated lung disease, and fewer cavitations. Following appropriate treatment, patients with M kansasii disease have an excellent prognosis.

Clinical features and follow up of 302 patients with Mycobacterium kansasii pulmonary infection: a 50 year experience

AIMS

To analyse clinical features and treatment outcomes of patients with pulmonary Mycobacterium kansasii infection treated at Hines VA Hospital between 1952 and 1995, and followed up until 2003.

FINDINGS

302 patients were confirmed to have M kansasii pulmonary infection; diagnosis was not made until death in 2%. The average age was 50 years old; 76% were white; all were men. Productive cough, dyspnoea, and chest pain were common; 16% were asymptomatic. Right sided, apical or subapical, thin walled cavitary infiltrate was the characteristic radiological feature. Heavy smoking, chronic obstructive pulmonary disease, alcoholism, peptic ulcer disease, coronary artery disease, prior tuberculosis, psychosis, prior pneumonia, and immunocompromising conditions were prevalent. Average follow up was 10 years and 2 months. PPD was positive in 58% of 179 tested. Two thirds of the patients required only first line drugs. Fourteen per cent required surgical intervention, none after 1977. Spontaneous resolution occurred in 1%. Aspergillosis developed in 4%. Bronchogenic carcinoma coexisted with M kansasii infection in 6% and followed it in 4%. Extrapulmonary malignancy coexisted with the infection in 4% and followed it in 6%; most involved head and neck. Eleven per cent of 224 deaths were attributed to M kansasii. Outcomes were affected by comorbidity, treatment compliance, rifampicin use, and extent of infection.

CONCLUSIONS

Prognosis of M kansasii pulmonary infection is good if diagnosed and treated early, together with control of underlying conditions. Clinicians should be aware of atypical radiological manifestations of the disease when coexisting with other pulmonary or immunocompromising conditions.

Mycobacterial lipomannan induces matrix metalloproteinase-9 expression in human macrophagic cells through a Toll-like receptor 1 (TLR1)/TLR2- and CD14-dependent mechanism

Lipomannans (LM) from various mycobacterial species were found to induce expression and secretion of the matrix metalloproteinase 9 (MMP-9) both in human macrophage-like differentiated THP-1 cells and in primary human macrophages. Inhibition studies using antireceptor-neutralizing antibodies are indicative of a Toll-like receptor 1 (TLR1)/TLR2- and CD14-dependent signaling mechanism. Moreover, LM was shown to down-regulate transcription of the metalloproteinase inhibitor TIMP-1, a major endogenous MMP-9 regulator.

[Phenotypic and genotypic characteristics of Mycobacterium kansasii strains isolated in Spain (2000-2003)]

INTRODUCTION

Mycobacterium kansasii is an opportunistic pathogen that mainly causes pulmonary infections. This species accounted for 9.7% of Mycobacteria other than tuberculosis complex identified in the reference laboratory of the Spanish Centro Nacional de Microbiologia during the period of 2000-2003.

METHODS

In this study we analyzed the phenotypic and genotypic characteristics of 298 M. kansasii strains isolated over this 4-year period. The phenotypic characteristics were determined by conventional methods: biochemical testing, culture and morphological study. Genotypic characteristics were studied using PCR restriction fragment analysis of a fragment of the hsp65 gene and digestion with BstEII and HaeIII, according to the method of Telenti.

RESULTS

Among the total of tested strains, 57.4% had the typical phenotypic characteristics described for M. kansasii. The rest had atypical patterns that we grouped into 17 biotypes. Strains belonging to six of the seven described genotypes were identified, with 86.6% of the strains falling into genotype I.

CONCLUSION

Analysis of the phenotypic characteristics of M. kansasii showed a higher discrimination index for intraspecific differentiation than genotypic methods. Nevertheless, the high variability of phenotypic characteristics, some of which were very specific for the species (e.g., photochromogenicity), could complicate their identification. Hence both conventional and molecular methods should be used to accurately identify the atypical isolates.

Clinical and Epidemiological Study of Disease Caused by Mycobacterium kansasii in the Metropolitan Area of Bilbao, Spain

OBJECTIVE

Epidemiological description of individuals from whom Mycobacterium kansasii isolates were obtained in respiratory samples, and analysis of the isolates using molecular biological techniques.

MATERIAL AND METHODS

A descriptive retrospective/ prospective study was carried out from January 1994 to April 2002 in Basurto Hospital and Santa Marina Hospital and from January 2000 to April 2002 in Cruces Hospital, Galdakao Hospital, and San Eloy Hospital. Diagnosis of the disease was performed according to American Thoracic Society criteria; other definitions were also applied to allow inclusion of all cases. Disease caused by M. kansasii in patients who were not infected with the human immunodeficiency virus (HIV) was compared with disease caused by Mycobacterium tuberculosis in a control group. Polymerase chain reaction was applied with analysis of restriction fragment length polymorphisms to differentiate between species of mycobacteria and classify them into genotypes. Amplified fragment length polymorphisms were used to recognize clones within each genotype.

RESULTS

The patient charts of 334 patients in which an isolate of M. kansasii had been recorded were reviewed. We considered 220 patients to be suffering from disease caused by M. kansasii (American Thoracic Society criteria along with probable disease according to established definitions). The disease was more frequent in male patients (n=185; 84.1%) and in individuals who were not HIV positive (n=184; 83.6%). The highest incidence of disease in the Bizkaia region was found in Margen Izquierda-Encartaciones, where the rate was 8.05 per 100 000 inhabitants. In the Bilbao area, the highest rate was found in the districts lying on the outskirts. The underlying diseases were tuberculosis (20.5%), chronic obstructive pulmonary disease (25.9%), pulmonary neoplasia (7.7%), silicosis (0.9%), chronic liver disease (11.4%), and duodenal ulcer (8.6%). The most frequent constitutional symptoms were fever (39.1%), loss of appetite (23.2%), and weight loss (33.3%). Among the respiratory symptoms, the most outstanding were cough (70.9%) and expectoration (62.3%). The most frequent radiographic patterns were cavitation and pulmonary infiltration. The most common treatment regimen was rifampicin, isoniazid, and ethambutol (43.4%), and the average duration was 12 months in patients who were HIV negative. Analysis of antibiotic sensitivity, performed on 56 strains, revealed that 100% were resistant to isoniazid, while none displayed rifampicin resistance. Thirty-four cases of disease caused by M. kansasii were compared with 68 cases of tuberculosis, all of them without HIV infection. The comparison revealed a predominance of smokers, respiratory symptoms, and cavitation in patients with disease caused by M. kansasii. The majority of the isolates (98.5%) corresponded to genotype I. A total of 8 clones were obtained; the clones designated 1 and 3 were more common in HIV-positive and HIV-negative individuals respectively.

CONCLUSIONS

In recent years, there has been an increase in the number of patients with disease caused by M. kansasii in the province of Bizkaia. The disease is more frequent in male patients, individuals who are HIV negative, and in urban areas. In addition, more respiratory symptoms and a higher incidence of cavitation were found in patients with disease caused by M. kansasii than in those with tuberculosis. Genotype I is the most common isolate, and clones 1 and 3 affect 80% of patients suffering from the disease.

Clinical patterns of cutaneous nontuberculous mycobacterial infections

BACKGROUND

Cutaneous nontuberculous mycobacterial infections result from external inoculation, spread of a deeper infection, or haematogenous spread of a disseminated infection. There are two species-specific infections (fish-tank or swimming-pool granuloma, due to Mycobacterium marinum, and Buruli ulcer, caused by M. ulcerans). Most infections, however, produce a nonspecific clinical picture.

OBJECTIVES

To define clinical patterns of cutaneous disease in nontuberculous mycobacterial infections.

METHODS

Fifty-one patients with cutaneous nontuberculous mycobacterial infections were reviewed. Clinical and histopathological features of normal hosts and immunosuppressed patients were compared. Two subgroups of immunosuppressed patients were distinguished: patients with cutaneous infection and patients with a disseminated infection and cutaneous involvement.

RESULTS

In immunosuppressed patients the number of lesions was significantly higher. Abscesses and ulceration were also more frequently observed. Different species were found in normal hosts and immunosuppressed patients. Several clinical patterns of cutaneous infection were defined: lymphocutaneous or sporotrichoid lesions; nonlymphocutaneous lesions at the site of trauma; folliculitis and furunculosis involving the lower extremities; disseminated lesions on the extremities in immunosuppressed patients. Two patterns were observed in patients with a disseminated infection: localized cutaneous lesions and disseminated cutaneous and mucosal lesions.

CONCLUSIONS

Cutaneous manifestations of nontuberculous mycobacterial infections may be classified according to criteria such as cutaneous lesions and immune status.

Comparative in vitro activities of linezolid, telithromycin, clarithromycin, levofloxacin, moxifloxacin, and four conventional antimycobacterial drugs against Mycobacterium kansasii

Mycobacterium kansasii is one of the most pathogenic and frequent nontuberculous mycobacteria isolated from humans. Patients with adverse drug reactions, resistant isolates, or suboptimal response require alternative treatment regimens. One hundred forty-eight consecutive clinical isolates of M. kansasii were tested for antimicrobial susceptibilities by the BACTEC 460 system (NCCLS) with two different inoculation protocols, one conventional and one alternative. In the alternative protocol, the inoculum 12B vial was incubated until the growth index was between 250 and 500. Four conventional antimycobacterial drugs (isoniazid, rifampin, streptomycin, and ethambutol) were studied with standard critical concentrations. The in vitro activities of linezolid, telithromycin, clarithromycin, levofloxacin, and moxifloxacin were determined by measuring radiometric MICs. All isolates tested were identified as M. kansasii genotype I and were resistant to isoniazid at a concentration of 0.4 mug/ml. One hundred twenty isolates (81.1%) were inhibited by 1 microg of isoniazid per ml. A high level of resistance to isoniazid (>10 microg/ml) was observed in six isolates (4.1%). Only five strains (3.4%) were resistant to rifampin (>1 microg/ml). All isolates studied were susceptible to streptomycin and ethambutol. The MICs at which 90% of the isolates were inhibited (in micrograms per milliliter) were as follows: linezolid, 1 (range, < or =0.25 to 2); telithromycin, >16 (range, 4 to >16); clarithromycin, 0.5 (range, < or =0.03 to 1); levofloxacin, 0.12 (range, 0.12 to 0.25); and moxifloxacin, 0.06 (range, < or =0.06 to 0.12). The susceptibility testing results with both inoculation protocols showed perfect correlation. In conclusion, all M. kansasii isolates showed decreased susceptibility to isoniazid, but resistance to rifampin was infrequent. Quinolones, especially moxifloxacin, were the most active antimicrobial agents tested, followed by clarithromycin. Linezolid also showed good activity against these microorganisms, but telithromycin's in vitro activity was poor.

Pneumonia caused by Mycobacterium kansasii in a series of patients without recognised immune defect

The clinical and epidemiological characteristics of 17 patients diagnosed with Mycobacterium kansasii pneumonia within a limited geographical region over a period of 10 years are described. An in-depth evaluation of the innate and adaptive immune systems was performed for five available patients. A comparison was made of the genetic fingerprint patterns of the isolates obtained by restriction fragment length polymorphism (RFLP) analysis, with the major polymorphic tandem repeat (MPTR) as a probe. Predisposing factors consisted of smoking, airway abnormalities, substance abuse, diabetes or poor general condition, but in two patients no risk factor was identified. In the five patients tested, no abnormalities or deficiencies were detected in the innate or adaptive type-1 immunity. All M. kansasii isolates had identical MPTR RFLP patterns, although no epidemiological connection could be established, and these were identical to those of clinical isolates from Australian patients. These data do not support the theory that defects in the innate or adaptive type-1 immunity have a role in the pathogenesis of invasive M. kansasii infections. The identical fingerprint patterns of the isolates suggested the existence of a virulent strain of M. kansasii.

Molecular analysis of Mycobacterium kansasii isolates from the United States

We studied the population genetics of Mycobacterium kansasii isolates from the United States by PCR restriction enzyme analysis (PRA) of the 441-bp Telenti fragment of the hsp-65 gene and pulsed-field gel electrophoresis (PFGE) of genomic DNA with the restriction endonucleases AseI, DraI, and XbaI, and we compared the patterns to those previously reported from France and Japan. By PRA, 78 of 81 clinical isolates (96%) from the United States belonged to subspecies I. With PFGE, 28 AseI patterns, 32 DraI patterns, and 35 XbaI patterns were produced. PFGE showed marked clonality of the U.S. isolates, with differences between genotypes involving only one or two bands. Isolates within Texas showed lower pattern diversity than those from different states. With DraI, 31 of 71 isolates (44%) had the same common PFGE pattern, which matched the predominant pattern in France (pattern Ia), determined by Picardeau et al. (M. Picardeau, G. Prod'hom, L. Raskine, M. P. LePennec, and V. Vincent, J. Clin. Microbiol. 35:25-32, 1997), and in Japan (type M), determined by Iinuma et al. (Y. Iinuma, S. Ichiyama, Y. Hasegawa, K. Shimokata, S. Kawahara, and T. Matsushima, J. Clin. Microbiol. 35:596-599, 1997). With AseI, 42% of isolates produced a common pattern indistinguishable from the common pattern seen in French isolates (Ia) and with only one band difference from the common pattern (type M) in Japan. This study demonstrates that subspecies I is the predominant subspecies of M. kansasii among clinical isolates in the United States, as it is in Europe and Japan, and that genotype I is highly clonal worldwide, with the same major genotype responsible for human infection. The fact that a single clone of M. kansasii is responsible for most cases of human disease suggests that specific virulence factors may be associated with this specific genotype.

Evaluation of a modified single-enzyme amplified-fragment length polymorphism technique for fingerprinting and differentiating of Mycobacterium kansasii type I isolates

The usefulness of single-enzyme amplified-fragment length polymorphism (AFLP) analysis for the subtyping of Mycobacterium kansasii type I isolates was evaluated. This simplified technique classified 253 type I strains into 12 distinct clusters. The discriminating power of this technique was high, and the technique easily distinguished between the epidemiologically unrelated control strains and our clinical isolates. Overall, the technique was relatively rapid and technically simple, yet it gave reproducible and discriminatory results. This technique provides a powerful typing tool which may be helpful in solving many questions concerning the reservoirs, pathogenicities, and modes of transmission of these isolates.

Pathologic features of Mycobacterium kansasii infection in patients with acquired immunodeficiency syndrome

CONTEXT

Mycobacterium kansasii is a slow-growing photochromogenic mycobacterium that may infect patients with human immunodeficiency virus (HIV) late in the course of acquired immunodeficiency syndrome (AIDS). The clinical features of pulmonary and extrapulmonary infections have been described in the literature; however, the pathology of infection has not been adequately addressed.

OBJECTIVE

This report describes the pathologic features of 12 cases of M kansasii infection in patients with AIDS.

DESIGN

The medical records, autopsy protocols, cytologic material, and histologic material from patients with AIDS and concomitant M kansasii infection at a tertiary-care medical center during 1990-2001 were reviewed.

RESULTS

Twelve cases were identified, 6 by autopsy, 5 of which were diagnosed postmortem. Four of the 12 cases had cytologic material and 4 cases had histologic biopsies available for review. Pulmonary infection was most common (9/12), and all patients in whom thoracic lymph nodes were assessed showed involvement (7/7). Abdominal infection was less frequent, with only 1 of 6, 2 of 6, and 2 of 6, demonstrating liver, spleen, and abdominal lymph node infection, respectively. Isolated infections without documented pulmonary infection included brain abscess (n = 1), ulnar osteomyelitis (n = 1), and paratracheal mass (n = 1). Cytologic and histologic material showed a wide range of inflammatory reactions, including granulomas with and without necrosis, neutrophilic abscesses, spindle-cell proliferations, and foci of granular eosinophilic necrosis. The M kansasii bacillus was characteristically long, coarsely beaded, and frequently showed folded, bent, or curved ends. Intracellular bacilli were randomly or haphazardly distributed within histiocytes.

CONCLUSION

Mycobacterium kansasii infection produces predominantly pulmonary infection in late-stage AIDS with a high incidence of thoracic lymph node involvement and a much lower incidence of dissemination to other sites. Infection is manifest as a wide variety of inflammatory reactions on cytology and histology; however, the characteristic appearance of the bacillus on acid-fast bacilli stain and its intracellular arrangement in histiocytes can allow a presumptive identification.

Nontuberculous mycobacteria in the environment

It is likely that the incidence of infection by environmental opportunistic mycobacteria will continue to rise. Part of the rise will be caused by the increased awareness of these microbes as human pathogens and improvements in methods of detection and culture. Clinicians and microbiologists will continue to be challenged by the introduction of new species to the already long list of mycobacterial opportunists (see Table 3). The incidence of infection will also rise because an increasing proportion of the population is aging or subject to some type of immunosuppression. A second reason for an increase in the incidence of environmental mycobacterial infection is that these microbes are everywhere. They are present in water, biofilms, soil, and aerosols. They are natural inhabitants of the human environment, especially drinking water distribution systems. Thus, it is likely that everyone is exposed on a daily basis. It is likely that certain human activities can lead to selection of mycobacteria. Important lessons have been taught by study of cases of hypersensitivity pneumonitis associated with exposure to metalworking fluid. First, the implicated metalworking fluids contained water, the likely source of the mycobacteria. Second, the metalworking fluids contain hydrocarbons (e.g., pine oils) and biocides (e.g., morpholine) both of which are substrates for the growth of mycobacteria [53,193]. Third, outbreak of disease followed disinfection of the metalworking fluid [136,137]. Although the metalworking fluid was contaminated with microorganisms, it was only after disinfection that symptoms developed in the workers. Because mycobacteria are resistant to disinfectants, it is likely that the recovery of the mycobacteria from the metalworking fluid [137] was caused by their selection. Disinfection may also contribute, in part, to the persistence of M avium and M intracellulare in drinking water distribution systems [33,89,240]. M avium and M intracellulare are many times more resistant to chlorine, chloramine, chlorine dioxide, and ozone than are other water-borne microorganisms [141,236]. Consequently, disinfection of drinking water results in selection of mycobacteria. In the absence of competitors, even the slowly growing mycobacteria can grow in the distribution system [33]. It is likely that hypersensitivity pneumonitis in lifeguards and therapy pool attendants [139] is caused by a similar scenario.

Management of disease due to Mycobacterium kansasii

Mycobacterium kansasii presents clinically in a manner most resembling tuberculosis. Diagnosis is usually not difficult; however, the significance of M kansasii isolates from some patients may be hard to determine. Usually, the presence of even one respiratory culture positive for M kansasii is sufficient to make a diagnosis, though few patients can have single respiratory culture positive for M kansasii without evidence of active disease. If not started on medication, these patients must be followed closely. Effective treatment can usually be accomplished with a rifampin-based regimen, or a rifabutin-based regimen for HIV-seropositive patients receiving antiretroviral therapy. Short course and intermittent regimens for treating M kansaii disease show promise but are not yet recommended for routine use.

Nontuberculous mycobacteria in the HIV infected patient

The reduction in disseminated NTM infections caused by HAART is one of the success stories in the history of HIV in the developed world. Despite this success, these diseases still occur and may have atypical presentations in patients receiving HAART. Clinicians treating HIV-infected patients must remain familiar with the diagnosis and treatment of these diseases and implement prevention strategies when indicated.

Mycobacterium tuberculosis mammalian cell entry operon (mce) homologs in Mycobacterium other than tuberculosis (MOTT)

The cloned mammalian cell entry gene mce1a from Mycobacterium tuberculosis confers to non-pathogenic Escherichia coli the ability to invade and survive inside macrophages and HeLa cells. The aim of this work was to search for and characterize homologs of the four M. tuberculosis mammalian cell entry operons (mce1, mce2, mce3 and mce4) in mycobacteria other than tuberculosis (MOTT). The dot-blot and polymerase chain reaction (PCR) experiments performed on 24 clinical isolates representing 20 different mycobacterial species indicated that the mce operons were widely distributed throughout the genus Mycobacterium. BLAST search results showed the presence of mce1, mce2 and mce4 homologs in Mycobacterium bovis, Mycobacterium avium and Mycobacterium smegmatis. A homologous region for the mce3 operon was also found in M. avium and M. smegmatis. DNA and protein alignments were done to compare the M. tuberculosis mce operons and the deduced M. bovis, M. avium, and M. smegmatis homologs. The deduced proteins of M. bovis mce1, mce2 and mce4 operons had 99.6-100% homology with the respective M. tuberculosis mce proteins (MTmce). The similarity between M. avium mce proteins and the individual M. tuberculosis homologs ranged from 56.2 to 85.5%. The alignment results between M. smegmatis mce proteins and the respective MTmce proteins ranged from 58.5% to 68.5%. Primer sets were designed from the M. tuberculosis mce4a gene for amplification of 379-bp fragments. Amplification was successful in 14 strains representing 11 different mycobacterial species. The PCR fragments were sequenced from 10 strains representing eight species. Alignment of the sequenced PCR products showed that mce4a homologs are highly conserved in the genus Mycobacterium. In conclusions, the four mce operons in different mycobacterial species are generally organized in the same manner. The phylogenetic tree comparing the different mce operons showed that the mce1 operon was closely related to the mce2 operon and mce3 diverged from the other operons. The wide distribution of the mce operons in pathogenic and non-pathogenic mycobacteria implicates that the presence of these putative virulence genes is not an indicator for the pathogenicity of the bacilli. Instead, the pathogenicity of these factors might be determined by their expression.

[Clinical importance of Mycobacterium kansasii and evaluation of the need to identify nontuberculous mycobacteria]

BACKGROUND

The aim of this study was to evaluate the clinical importance of a single isolation of Mycobacterium kansasii in order to determine whether a single isolation of nontuberculous mycobacteria is sufficient to diagnose mycobacteriosis or whether multiple isolations are required, in which case, it would be better to wait until a second isolation is produced before undertaking identification of all nontuberculous mycobacteria.

PATIENTS AND METHODS

Between 1992-1998, we studied the characteristics of 77 isolates of M. kansasii because it is the nontuberculous mycobacterium most frequently associated with disease. Our hospital has 500 beds but processed the samples from the Principe de Viana Outpatient Center and those from the district hospitals of Tudela and Estella for mycobacteria. During the study period, a mean of 3,900 specimens were processed per year. The isolates came from 22 episodes in 21 patients (19 males and 2 females). The specimens were cultured using standard techniques and confirmation was performed using gene probes (Gen-Probe, San Diego, California).

RESULTS

Of the 22 episodes, positive cultures were obtained on multiple occasions in 15 (68.1%) and a single isolation was obtained in 7. All isolations came from respiratory samples. Isolations were obtained from blood on only 2 occasions (both in HIV-positive patients). Direct bacilloscopy was positive in 60% of cases with multiple isolations and negative in all cases of single isolation. Multiple isolations were found in 14 patients, 7 of whom were HIV-positive and with advanced immunodepression and 7 were HIV-negative. Of these, two were alcoholics and the remaining patients had chronic pulmonary diseases. All treated patients showed initial improvement after specific therapy and negative bacilloscopies and cultures. None of the patients with a single isolation, including two HIV-positive patients, showed clinical repercussions.

CONCLUSION

In our experience, a single isolation of M. kansasii was without clinical importance, even in two HIV-positive patients. Given that when the criteria of the American Thoracic Society for the diagnosis of mycobacteriosis are followed, in general, multiple mycobacteria should be isolated, a strategy of not undertaking the identification of all nontuberculous mycobacteria until a second isolation is produced can be established, unless there is serious clinical indication to suggest otherwise.

Cutaneous and mediastinal lymphadenitis due to Mycobacterium kansasii

Mycobacterium kansasii most commonly causes a slowly progressive pulmonary disease. Skin and disseminated infections are seen less frequently and only in immunocompromised hosts. To our knowledge, no case of Mycobacterium kansasii infection or skin infection associated with additional organ involvement in an immunocompetent patient has been reported.

Primary cutaneous Mycobacterium kansasii infection in a child

A 6-year-old girl with a primary cutaneous form of Mycobacterium kansasii infection is presented. Disseminated infection and immune deficiency were excluded in our patient. She was successfully treated with surgical excision and oral erythromycin. Primary cutaneous M. kansasii is an exceedingly rare infection in children.