Mycobacterium abscessus infection after use of tumor necrosis factor α inhibitor therapy: case report and review of infectious complications associated with tumor necrosis factor α inhibitor use

Fish Tank-Associated Mycobacterium Marinum Infection in an Immunocompromised Host

Mycobacterium marinum infection can be challenging to diagnose and treat, especially in immunocompromised patients on tumour necrosis factor alpha inhibitors. A patient with collagenous colitis on infliximab presented with ulcerated plaques accompanied by nodules in a sporotrichoid fashion. Initial treatments failed until a biopsy confirmed M. marinum Multiple antibiotic regimens, including rifampicin and ciprofloxacin, were required due to resistance. The case underscores the importance of patient education on avoiding aquatic environments, considering atypical mycobacterial infections in differentials for immunocompromised patients with sporotrichoid lesions, and prioritising urgent diagnostic biopsies. Treatment can be lengthy, often requiring up to 12 months, emphasising the need for ongoing patient counselling and multidisciplinary management. Current guidelines recommend a combination of ethambutol and macrolides, though further research is necessary to optimise treatment protocols.

Mycobacterium abscessus: It's Complex

Mycobacterium abscessus (M. abscessus) is an opportunistic pathogen usually colonizing abnormal lung airways and is often seen in patients with cystic fibrosis. Currently, there is no vaccine available for M. abscessus in clinical development. The treatment of M. abscessus-related pulmonary diseases is peculiar due to intrinsic resistance to several commonly used antibiotics. The development of either prophylactic or therapeutic interventions for M. abscessus pulmonary infections is hindered by the absence of an adequate experimental animal model. In this review, we outline the critical elements related to M. abscessus virulence mechanisms, host-pathogen interactions, and treatment challenges associated with M. abscessus pulmonary infections. The challenges of effectively combating this pathogen include developing appropriate preclinical animal models of infection, developing proper diagnostics, and designing novel strategies for treating drug-resistant M. abscessus.

Clinical Performance of Mycobacterial Immunohistochemistry in Anatomic Pathology Specimens

OBJECTIVES

Diagnosis of mycobacterial infections poses significant challenges in anatomic pathology. We recently described the use of antimycobacteria immunohistochemistry (IHC) as a sensitive, efficient diagnostic tool and now report the clinical performance of this assay among general, noninfectious disease pathology-trained anatomic pathologists.

METHODS

Over a 2-year period, all cases were retrospectively identified in which mycobacterial IHC was performed during routine diagnostic workup.

RESULTS

From October 2017 to September 2019, mycobacterial IHC was evaluated for 267 cases, resulting in 58 (22%) positive stains. Compared with culture and molecular results, the sensitivity and specificity of IHC were 52% and 80%, respectively. IHC performed significantly better than acid-fast bacilli (AFB) staining (Ziehl-Neelsen) (P < .0001; sensitivity 21%, specificity 92%) but similarly to modified AFB staining (mAFB; Fite-Faraco) (P = .9; sensitivity 61%, specificity 84%). In cases with discordant IHC and mAFB staining, there were no differences in rates of culture or polymerase chain reaction-confirmed positivity.

CONCLUSIONS

Mycobacterial IHC was well adopted with superior clinical performance to AFB and comparable performance to mAFB. These results support the use of IHC as an adjunctive tool in the diagnosis of mycobacterial infections and suggests its potential role as a rapid screening test for molecular testing.

Non-tuberculous mycobacteria and the rise of Mycobacterium abscessus

Infections caused by non-tuberculous mycobacteria (NTM) are increasing globally and are notoriously difficult to treat due to intrinsic resistance of these bacteria to many common antibiotics. NTM are diverse and ubiquitous in the environment, with only a few species causing serious and often opportunistic infections in humans, including Mycobacterium abscessus. This rapidly growing mycobacterium is one of the most commonly identified NTM species responsible for severe respiratory, skin and mucosal infections in humans. It is often regarded as one of the most antibiotic-resistant mycobacteria, leaving us with few therapeutic options. In this Review, we cover the proposed infection process of M. abscessus, its virulence factors and host interactions and highlight the commonalities and differences of M. abscessus with other NTM species. Finally, we discuss drug resistance mechanisms and future therapeutic options. Taken together, this knowledge is essential to further our understanding of this overlooked and neglected global threat.

Etanercept in Rheumatoid Arthritis: Long Term Anti-Inflammatory Efficacy in Clinical Practice

Rheumatoid Arthritis (RA) is a chronic inflammatory disease of erosive nature that tends to progress to juxta-articular destruction and ankylosis. The pathological events that lead to joint destruction are due, in part, to an enhanced expression of Tumour Necrosis Factor (TNF). It has been shown that TNF-α blocking agents significantly reduce joint inflammation and slow down the progression of radiographic joint damage. Etanercept is a biological drug obtained through recombinant DNA techniques that acts by inhibiting the cellular response mediated by TNF. The aim of this study is to evaluate the efficacy and tolerance of Etanercept in patients affected by active Rheumatoid Arthritis non- responsive to standard traditional therapies. All patients presented an improvement in the illness. Our study concords with the most recent data from literature that Etanercept acts rapidly and offers a quick and long-lasting reduction of illness activity, as well as an improvement in functional capability and quality of life in patients affected by active RA.

Mycobacterial diseases developed during anti-tumour necrosis factor-α therapy

Nontuberculous mycobacterial (NTM) disease and tuberculosis (TB) develop during anti-tumour necrosis factor (TNF)-α therapy. We compared clinical characteristics and outcomes between the two diseases. A total of 1165 patients were screened for TB and treated with TNF-α antagonists from July 2004 to July 2013 for the following conditions: inflammatory bowel disease (n = 422), rheumatoid arthritis (n = 320), and ankylosing spondylitis (n = 389). TB and NTM disease were diagnosed at baseline screening in four and three patients, respectively, and developed during anti-TNF-α therapy in 19 and six patients, respectively. The incidence rate of TB and NTM disease was 747.7 per 100 000 and 238.2 per 100 000 person-years, respectively. Patients with NTM disease were older, with a greater proportion of females. All cases of NTM disease involved the lung, with rheumatoid arthritis (83.3%) being the most frequent underlying disease. The most common radiological feature was consolidation in NTM disease, and honeycombing was present in two rheumatoid arthritis patients with NTM disease. The most common pathogen was Mycobacterium intracellulare (n = 3) followed by Mycobacterium avium (n = 2). Both the NTM and TB group showed favourable outcomes. The clinical characteristics differed between NTM disease and TB that developed on anti-TNF-α agents, but clinical outcomes were favourable in both diseases.

Mortality in inflammatory bowel disease patients under 65 years of age

OBJECTIVE

To assess mortality in inflammatory bowel disease (IBD) patients under 65 years of age and to identify the factors related to death in this age group. METHODS. We studied 2570 IBD patients who were diagnosed as having disease before 65 years of age and attended a single tertiary referral center area between 1983 and 2012. Follow-up was censored at 65 years. The causes of death were determined from death certificates obtained from the Irish registry office of births, marriages and deaths. Observed all-cause survival was compared with expected survival of persons of the same age and sex in the general population. Expected survival was obtained from national life tables produced by the central statistics office. Survival estimates were calculated for disease type, disease site, gender, the presence of primary sclerosing cholangitis (PSC), immunomodulator use, biologic therapy use, presence of fistulating disease and prior surgery.

RESULTS

Fifty-two deaths were reported in the population younger than 65 years, of which 41 were IBD related. We found little difference in survival in the first 25 years of follow-up, but relative survival decreased in both the Crohn's disease (CD) and ulcerative colitis (UC) cohort thereafter, so that 30-year mortality was excessive in both groups. An adjusted multivariate regression analysis of patients with CD identified PSC as the only predictor of premature mortality (p = 0.003). PSC was also identified as the only independent predictor of mortality in UC patients (p = 0.03).

CONCLUSIONS

The presence of PSC poses the greatest risk for mortality in both UC and CD.

Prognostic factors and radiographic outcomes of nontuberculous mycobacterial lung disease in rheumatoid arthritis

OBJECTIVE

The aims of our study were to retrospectively review patients with rheumatoid arthritis (RA) with nontuberculous mycobacterial (NTM) lung disease, to assess the prognostic factors, and to analyze the time to disease deterioration according to the antirheumatic drugs received during the NTM lung disease followup period.

METHODS

We retrospectively analyzed medical records of 98 HIV-negative RA patients with NTM lung disease treated at our institution, and investigated potential risk factors of mortality with Cox regression analysis. Time to radiologic deterioration was evaluated if antirheumatic drugs were not changed during observational periods and computed tomography was performed once each year.

RESULTS

Mean patient age was 67.6 years, and median followup period was 4.4 years. NTM species included Mycobacterium avium complex (83.7%), M. kansasii (6.1%), M. gordonae (6.1%), and others (4.1%). Radiographic features included nodular/bronchiectatic (NB) disease (57.1%), fibrocavitary (FC) disease (14.3%), FC+NB disease (16.3%), and other types (12.2%). Initial management included observation in 74 (75.5%) patients. Negative prognostic factors of mortality were C-reactive protein (CRP) ≥ 1.0 mg/dl and radiographic features of FC, FC+NB, or other disease types. Median time to radiologic deterioration was 3.6 years. Erythrocyte sedimentation rate (ESR) > 50 mm/h was a negative prognostic factor of radiologic deterioration.

CONCLUSION

The most frequent NTM species was M. avium complex. CRP and radiographic features were prognostic factors for all-cause mortality, and ESR was a prognostic factor of radiologic deterioration. Further studies are warranted focusing on time to disease deterioration according to antirheumatic drug received during NTM followup.

Pharmacokinetics and toxicology of therapeutic proteins: Advances and challenges

Significant progress has been made in understanding pharmacokinetics (PK), pharmacodynamics (PD), as well as toxicity profiles of therapeutic proteins in animals and humans, which have been in commercial development for more than three decades. However, in the PK arena, many fundamental questions remain to be resolved. Investigative and bioanalytical tools need to be established to improve the translation of PK data from animals to humans, and from in vitro assays to in vivo readouts, which would ultimately lead to a higher success rate in drug development. In toxicology, it is known, in general, what studies are needed to safely develop therapeutic proteins, and what studies do not provide relevant information. One of the major complicating factors in nonclinical and clinical programs for therapeutic proteins is the impact of immunogenicity. In this review, we will highlight the emerging science and technology, as well as the challenges around the pharmacokinetic- and safety-related issues in drug development of mAbs and other therapeutic proteins.

Is continuation of anti-tumor necrosis factor-α therapy a safe option for patients who have developed pulmonary mycobacterial infection? : Case presentation and literature review

Continuation of anti-tumor necrosis factor-α (TNFα) therapy generally has not been recommended for patients who have developed nontuberculous mycobacterial (NTM) diseases; in daily practice, however, we often encounter patients with refractory rheumatoid arthritis (RA) who experience uncontrollable flares following withdrawal of anti-TNFα agents. Here, we report a case of pulmonary NTM disease caused by Mycobacterium intracellulare occurring in a patient with refractory RA undergoing etanercept therapy. Since there was the concern of an exacerbation of RA symptoms, etanercept was continued during anti-NTM therapy. The patient's pulmonary symptoms and radiological abnormalities were found to have markedly improved in a relatively short time period after beginning the anti-NTM therapy. Additionally, her RA symptoms were adequately controlled without the occurrence of any unexpected adverse events. The continuation of etanercept therapy may be a safe option during anti-NTM therapy if patients' underlying diseases would otherwise be difficult to control. Strictly supervised anti-NTM therapy and patients' informed consent are mandatory. We review the medical literature on NTM disease associated with anti-TNFα therapy for rheumatic diseases and discuss the safety of simultaneous use of anti-TNFα agents in patients during anti-NTM therapy.

Tumour necrosis factor inhibitors and infection: What is there to know for infectious diseases physicians?

At this year's meeting of Digestive Disease Week in Los Angeles, California, it was noted that antitumour necrosis factor (anti-TNF) inhibitors showed further evidence of efficacy in Crohn's disease (1). TNF antagonists have been used increasingly in the treatment of a number of other inflammatory diseases, especially rheumatoid arthritis (RA), where they have revolutionized treatment (2). At the same time, their use has been associated with an increased risk of serious infections (3). As more patients are treated with these agents, it is inevitable that infectious diseases physicians will see a variety of infections, both common and uncommon, requiring familiarity with this new class of drugs and their infectious complications.

Mycobacterium marinum infection complicated by anti-tumour necrosis factor therapy

Mycobacteria other than tuberculosis infections in patients taking various tumour necrosis factor (TNF)-α inhibitors have been reported in the literature. We describe sporotrichoid spread of Mycobacterium marinum in a man with Crohn's disease treated with infliximab. After starting ethambutol and rifampicin and discontinuing infliximab, a worsening appeared. M. marinum infection may have a potential local spread and systemic dissemination in patients treated with TNF-α inhibitors.

Host immune response to rapidly growing mycobacteria, an emerging cause of chronic lung disease

Rapidly growing mycobacteria (RGM) are environmental organisms classified under the broader category of nontuberculous mycobacteria. The most common RGM to cause human diseases are Mycobacterium abscessus, Mycobacterium chelonae, Mycobacterium fortuitum, and Mycobacterium massiliense. Infections due to the RGM are an emerging health problem in the United States. Chronic pulmonary disease and skin/soft-tissue infections are the two most common disorders due to these organisms. Clinical outcomes in the treatment of M. abscessus infections are generally disappointing. Because less is known about the nature of the immune response to M. abscessus than for tuberculosis, we herein highlight the major clinical features associated with infections due to M. abscessus and other RGM, and review the known host immune response to RGM, drawing from experimental animal and clinical studies. Based on in vitro and in vivo murine models, Toll-like receptor 2, dectin-1, tumor necrosis factor (TNF)-α, IFN-γ, leptin, T cells, and possibly neutrophils are important components in the host defense against RGM infections. However, excessive induction of TNF-α by the R morphotype of M. abscessus may allow it to be more pathogenic than the S morphotype. Clinical observations and/or genetic studies in humans corroborate many of the findings in animals in that those with cell-mediated immunodeficiency, genetic defects in IFN-γ-IL-12 axis, and those individuals on TNF-α blockers are at increased risk for nontuberculous mycobacteria infections, including the RGM. However, much remains to be discovered on why seemingly healthy individuals, particularly slender postmenopausal women with thoracic cage anomalies, appear to be at increased risk.

[Cutaneous infection due to Mycobacterium chelonae during anti-TNF therapy]

BACKGROUND

Mycobacterium chelonae is a ubiquitous, rapidly growing, opportunistic, non-tuberculous mycobacterium that can cause skin and bone tissue infections. We report a case of cutaneous infection due to M. chelonae following anti-TNF therapy.

CASE REPORT

A 70-year-old woman with a medical history of rheumatoid arthritis was admitted for several purple nodular cutaneous lesions on her right leg evolving for 2 months. At admission, she was on prednisone, methotrexate and adalimumab for her rheumatoid arthritis. Skin lesions appeared 5 days before etanercept, which was taken for 5 months before being discontinued for adalimumab. Both the histopathological examination and bacterial culture of involved skin showed the presence of M. chelonae. Adalimumab was immediately discontinued and a combination of amoxicillin-clavulanic acid and tigecyclin was started.

DISCUSSION

TNF-alpha plays a pivotal role in immune reaction to intracellular pathogens. Very few cases of cutaneous infection involving M. chelonae in association with an anti-TNF-alpha therapy have been reported in the literature. To our knowledge, this is the first case occurring during treatment with etanercept and symptoms worsened with the introduction of adalimumab. In addition, this case underlines the difficulties of effectively treating this mycobacterium.

Latent infection and tuberculosis disease in rheumatoid arthritis patients

New drug classes, biologics, have been developed over the past 10 years based on human or chimeric antibodies against cytokines or receptors with pivotal roles in the inflammatory pathways of immune-mediated inflammatory disease. Anti-tumor necrosis factor agents carry the largest infection risk of all the biologics, predisposing patients to mycobacterial infections. Patients receiving biologics are at higher risk for developing tuberculosis. New cases of tuberculosis or reactivation of latent tuberculosis infections may occur during the course of treatment, so a high level of vigilance is highly recommended.

Olecranon bursitis secondary to Mycobacterium kansasii infection in a patient receiving infliximab for Behçet's disease

We present a case of Mycobacterium kansasii olecranon bursitis in a woman with known immunosuppression secondary to the treatment received for her Behçet's disease. We found only one other case report of olecranon bursitis caused by M. kansasii in the literature, which, unlike our case, presented in an immunocompetent adult following trauma. This case extends the range of opportunistic mycobacterial infections that are associated with anti-tumour necrosis factor therapy.

The risk of infections with biologic therapies for rheumatoid arthritis

OBJECTIVES

To assess the risk of serious and nonserious bacterial and viral infections associated with the use of biologic therapy (abatacept, adalimumab, anakinra, etanercept, infliximab, and rituximab) in patients with rheumatoid arthritis (RA).

METHODS

Information was derived from PubMed, EMBASE, and the Cochrane clinical trials register and database of systematic reviews and relevant congress abstracts up to and including February 2008.

RESULTS

Compared with the general population, patients with RA have a heightened risk of infection, including tuberculosis. Long-term clinical trials and postmarketing studies indicate that anakinra and the tumor necrosis factor (TNF) inhibitors are associated with an increased risk of infections versus conventional disease-modifying antirheumatic drugs (DMARDs), especially early in the course of treatment. The most common sites of infection are the respiratory tract (including pneumonia), skin and soft tissue, and the urinary tract. The risk of tuberculosis also appears higher with TNF inhibitors (in particular, infliximab) versus DMARDs, although this can be reduced by screening and prophylaxis. TNF inhibitors do not appear to significantly increase the risk of reactivating chronic viral infections. Influenza and pneumococcal vaccinations are generally effective in the face of TNF inhibitors or abatacept. Available data suggest that the risk of infections and serious infections with abatacept and rituximab may be similar to that of the TNF inhibitors. To date, there have been no reports from clinical trials of increased tuberculosis or opportunistic infections with abatacept or rituximab.

CONCLUSIONS

All marketed TNF inhibitors for compared to control RA appear to increase the risk of serious and nonserious infections compared with DMARDs. Although suggestive, data for abatacept and rituximab are less definitive and longer periods of patient exposure to these agents are needed before an assessment of their risks can be made.

Nontuberculous mycobacterial infections

CONTEXT

Nontuberculous mycobacteria include numerous acid-fast bacilli species, many of which have only recently been recognized as pathogenic. The diagnosis of mycobacterial disease is based on a combination of clinical features, microbiologic data, radiographic findings, and histopathologic studies.

OBJECTIVE

To provide an overview of the clinical and pathologic aspects of nontuberculous mycobacteria infection, including diagnostic laboratory methods, classification, epidemiology, clinical presentation, and treatment.

DATA SOURCES

Review of the pertinent literature and published methodologies.

CONCLUSIONS

Nontuberculous mycobacteria include numerous acid-fast bacilli species, many of which are potentially pathogenic, and are classified according to the Runyon system based on growth rates and pigment production. Their slow growth hinders cultures, which require special medium and prolonged incubation. Although such methods are still used, newer nucleic acid-based technologies (polymerase chain reaction and hybridization assays) can rapidly detect and speciate some mycobacteria--most notably, distinguishing Mycobacterium tuberculosis from other species. Infections caused by these organisms can present as a variety of clinical syndromes, not only in immunocompromised patients but also in immunocompetent hosts. Most common among these are chronic pulmonary infections, superficial lymphadenitis, soft tissue and osteoarticular infections, and disseminated disease. Treatment of nontuberculous mycobacterial infections is difficult, requiring extended courses of multidrug therapy with or without adjunctive surgical intervention.

Targets of anticytokine therapy and the risk of infections in humans and mice

PURPOSE OF REVIEW

To examine the type and risk of infections in humans and mice deficient in proinflammatory cytokines. Naturally occurring or manipulated genetic defects of tumor necrosis factor, interleukins-1, -6, -12, and -15, and interferon-gamma are examined for their increased susceptibility to, or protection from, infection.

RECENT FINDINGS

Interleukin-12p40 and interferon-gamma-blockers may lead to increased incidence of infections with intracellular bacteria, parasites, and fungi. In addition, we may see viral infections with interferon-gamma-blockers. Increased risk of infections is unlikely with either interleukin-1- or interleukin-15-blockers. Interleukin-6-blockers may lead to increased risk of infection with extracellular bacteria, viruses, parasites and fungi.

SUMMARY

In tumor necrosis factor knockout mice, increased susceptibility to pathogens are reported that are normally controlled by granuloma formation. In patients treated with tumor necrosis factor-blockers, a two-fold increase of granulomatous infections, predominantly reactivation of latent tuberculosis, is found. The infections detected in tumor necrosis factor knockout mice were accurate for predicting the infections observed when using tumor necrosis factor-blockers. If a similar correlation exists for other cytokines, the use of interferon-gamma and interleukin-12p40 blockers, and possibly interleukin-6 blockers, will lead to an increased risk for severe infections. Care should be taken when new cytokine blockers/antagonists are introduced.

Reduction of chemokine secretion in response to mycobacteria in infliximab-treated patients

The use of anti-tumor necrosis factor (TNF) agents as a treatment for chronic inflammatory conditions has been shown to be associated with an increased risk of developing tuberculosis. We studied the effect of the anti-TNF antibody infliximab on antimycobacterial immunity in 26 patients with rheumatoid arthritis or ankylosing spondylitis by use of an in vitro whole-blood model employing a reporter mycobacterium. Blood samples taken before and 30 min and 7 days after a 2-hour infliximab infusion were compared in terms of their abilities both to suppress luminescence of Mycobacterium bovis bacillus Calmette-Guérin lux and to secrete chemokines and cytokines 24 and 96 h after infection. No immediate effect of infliximab on mycobacterial luminescence was detected using this bioassay, irrespective of whether patients were receiving their first (n = 14) or maintenance (n = 12) doses of infliximab. Moreover, no effect on mycobacterial luminescence was detected when blood was taken 7 days after infliximab treatment (n = 7). By contrast, there was a significant reduction in the chemokines implicated in cellular trafficking, namely, interleukin-8, macrophage-inhibitory protein-1alpha (MIP-1alpha), MIP-1beta (24 h and 96 h), and monocyte chemoattractant protein-1 (MCP-1) (24 h) following BCG lux strain infection in the 30-minute post-infliximab-infusion blood samples (P < 0.05). This effect was sustained by MIP-1beta and MCP-1 (24 h; P < 0.05) at 7 days after infusion. Our results suggest that the development of tuberculosis in infliximab-treated patients is not directly related to the mycobactericidal effects of TNF but may be due to inhibition of TNF-dependent chemokine gradients disrupting cellular migration necessary to maintain the integrity of the granuloma.

Update on the Japanese guidelines for the use of infliximab and etanercept in rheumatoid arthritis

Application of biological agents targeting tumor necrosis factor-alpha (TNF-alpha) caused a paradigm shift in the treatment of rheumatoid arthritis (RA). The introduction of infliximab in 2003 and etanercept in 2005 in Japan had a significant impact on both Japanese rheumatologists and RA patients, although serious adverse effects such as bacterial pneumonia, tuberculosis and Pneumocystis jiroveci pneumonia are significant concerns. Based on the data from post-marketing surveillance in Japan and accumulating evidence worldwide, the Internal Medicine Rheumatology Study Group of the Ministry of Health, Labor and Welfare (MHLW), Japan, has updated the guidelines for the use of anti-TNF-alpha agents for RA, which were subsequently approved by the Board of Japan College of Rheumatology (JCR). In the present revised guidelines, we combined the guidelines for use of each of infliximab and etanercept together with some modifications and precautions, paying special attention to serious adverse reactions. Although it is still controversial whether the use of TNF-alpha blocking agents per se increases the risk of infection or not, bacterial pneumonia, regardless of the pathogens, is the most frequent complications in RA. The risk factors associated with pneumonia identified in the post-marketing surveillance of infliximab in Japan are presented in this guideline. The diagnostic algorithm is also designed for early diagnosis and treatment of pulmonary lesions seen during the treatment of biological agents. Preventive measures and precautions against tuberculosis, another frequent and significant complication in Japan, are also described. Furthermore, risk factors for developing Pneumocystis pneumonia, which uniquely occurs at 30- to 50-fold frequency under TNF-alpha blockade therapy in Japan, are described here and its preventive measures are discussed. It is stressed that secondary-care rheumatologists should be better familiarized with the proper use of TNF-alpha blocking agents and be alert to any adverse events for a better management of RA patients.

Importance of T cells, gamma interferon, and tumor necrosis factor in immune control of the rapid grower Mycobacterium abscessus in C57BL/6 mice

Mycobacterium abscessus is an emerging rapidly growing mycobacterium that causes tuberculous-like lesions in humans. We studied the immune control of this organism in C57BL/6 mice challenged intravenously with 10(7) CFU. Bacteria were eliminated from both the spleen and the liver within 90 days, and liver histology showed organized granulomatous lesions. A T- and B-cell requirement was investigated by challenging Rag2-/-, Cd3epsilon-/-, and muMT-/- mice. Rag2-/- and Cd3epsilon-/- mice were significantly impaired in the ability to clear M. abscessus from the liver and spleen, and muMT-/- mice were significantly impaired in the ability to clear M. abscessus from the liver, suggesting that infection control was primarily T cell dependent in the spleen and both T and B cell dependent in the liver. The liver granulomatous response was similar to that of wild-type controls in muMT-/- mice but completely absent in Cd3epsilon-/- and Rag2-/- mice. We studied the involvement of gamma interferon (IFN-gamma) and tumor necrosis factor (TNF) by challenging C57BL/6 mice deficient in the IFN-gamma receptor (Ifngr1-/-) and in TNF (Tnf-/-). Ifngr1-/- mice were significantly impaired in M. abscessus control both in the spleen and in the liver, and granulomas were profoundly altered. The effect was even more substantial in Tnf-/- mice; they failed to control M. abscessus infection in the liver and died within 20 to 25 days after infection with many hepatic inflammatory foci and major lesions of ischemic necrosis in the liver and kidney. These features were not observed with the closely related species M. chelonae. T-cell immunity, IFN-gamma, and TNF are central factors for the control of M. abscessus in C57BL/6 mice, as they are for the control of pathogenic slowly growing mycobacteria.

Pulmonary Mycobacterium szulgai infection and treatment in a patient receiving anti-tumor necrosis factor therapy

BACKGROUND

A 54-year-old man with a 22-year history of rheumatoid arthritis and an 8-year history of chronic obstructive pulmonary disease presented with dyspnea on exertion, nonproductive cough and fatigue of 1 month's duration. His medication at presentation consisted of etanercept, azathioprine, naproxen and inhaled fluticasone and salbutamol.

INVESTIGATIONS

At presentation, the patient underwent physical examination, chest X-ray and high-resolution CT, blood tests, and bronchoalveolar lavage fluid analysis including auramine stains and gene sequence analysis of cultured Mycobacterium szulgai. The patient underwent minithoracotomy after 6 months, and bronchoalveolar lavage fluid analysis, culture and chest X-ray after 18 months. Further chest imaging and culture of sputum samples were performed another year later.

DIAGNOSIS

Pulmonary M. szulgai infection.

MANAGEMENT

Triple drug therapy with rifampicin, ethambutol hydrochloride and clarithromycin. Anti-tumor necrosis factor treatment was continued.

Severe sporotrichoid fish tank granuloma following infliximab therapy

Mycobacterium marinum is an atypical mycobacterium usually found in non-chlorinated water. It rarely disseminates, except in the setting of a severely immunosuppressed patient, and usually follows a sporotrichotic type of distribution. We report the case of a 45-year-old man who had ankylosing spondylitis and was receiving infliximab and isoniazid for latent tuberculosis. The patient presented with a 5-month history of painful erythematous and suppurative nodules and abscesses on the right upper extremity. M. marinum was not isolated in cultures and histologic findings together with clinical examination provided evidence of sporotrichoid-like fish tank granuloma. The patient was treated with rifampin (rifampicin) and ethambutol for 8 months and responded satisfactorily while continuing to receive infliximab. In accordance with data in the published literature, isoniazid proved ineffective in preventing M. marinum infection in this patient. While mycobacterial complications of tumor necrosis factor-alpha (TNFalpha) inhibitor therapy are well established, our case appears to be the first reported instance of M. marinum infection in a patient taking infliximab. As anti-TNFalpha agents become increasingly used for a variety of conditions, awareness of the potential infectious complications associated with use of these agents will be vital for clinicians.

Mycobacterium abscessus: an emerging rapid-growing potential pathogen. Review article

Mycobacterium abscessus is the most pathogenic and chemotherapy-resistant rapid-growing mycobacterium. It is commonly associated with contaminated traumatic skin wounds and with post-surgical soft tissue infections. It is also one of the mycobacteria that are most often isolated from cystic fibrosis patients. It is essential to differentiate this species from the formerly indistinct "M. chelonae-complex", as chemotherapy is especially difficult in M. abscessussenso strictu. Clarithromycin or azithromycin are the only regular oral antimycobacterial agents with an effect on M. abscessus, and should preferably be supplemented with other drugs since long-term monotherapy may cause resistance. Amikacin is a major parenteral drug against M. abscessus that should also be given in combination with another drug. The recently introduced drug tigecycline may prove to be an important addition to chemotherapy, but has yet to be fully clinically evaluated as an antimycobacterial agent. Surgery can be curative, or at least helpful, in the healing of M. abscessus infection, and if conducted, it should include the removal of all foreign or necrotic material. There is increasing awareness of M. abscessus as an emerging pathogen.