Mycobacterium xenopi Killer Cell–Deficient Patient with Clarithromycin, Rifabutin, and Sparfloxacin
Transcription
Mycobacterium xenopi Killer Cell–Deficient Patient with Clarithromycin, Rifabutin, and Sparfloxacin
120 Successful Treatment of Pulmonary Mycobacterium xenopi Infection in a Natural Killer Cell–Deficient Patient with Clarithromycin, Rifabutin, and Sparfloxacin Hans Schmitt, Norbert Schnitzler, Jochen Riehl, Gerhard Adam, Heinz-Gu¨nter Sieberth, and Gerhard Haase From the Departments of Internal Medicine II and Diagnostic Radiology, and the Institutes of Medical Immunology and Medical Microbiology, University Hospital Rheinisch–Westfa¨lische Technische Hochschule Aachen, Aachen, Germany Mycobacterium xenopi is a ubiquitous thermophilic bacterium occurring predominantly in water; its detection in clinical samples is usually associated with contamination or asymptomatic transient colonization [1– 4]. However, in the past few years an increasing number of clinically relevant M. xenopi infections, including nosocomial transmissions, have been reported [5–9]. A common route of infection is aerosol spread via inhalation of contaminated water. Clinical and radiological examinations reveal pulmonary inflammation with cavitary lesions, not easily distinguishable from tuberculosis [2, 3, 7–17]. Patients with a serious history of lung disease or severe immunodeficiency due to different causes (e.g., AIDS or organ transplantation) are most commonly affected [5, 9, 18 –26]. Disseminated M. xenopi infection is rarely observed [27, 28]. In a recently published study, clinically relevant disease was diagnosed for 10 of 103 patients from whom M. xenopi was isolated [5]. Therefore, it is difficult to determine the etiologic role of this bacterium and the resulting therapeutic indications. We report herein a young man with severe pulmonary M. xenopi infection successfully treated with a novel combination therapy. Although severe immunodeficiency could be excluded, there was a great reduction in the number of natural killer cells (NKCs). Received 27 August 1998; revised 12 February 1999. H.S. and N.S. made equal contributions to the manuscript and thus are both considered first authors. Reprints or correspondence: Dr. Gerhard Haase, Institute of Medical Microbiology, University Hospital RWTH Aachen, D-52057 Aachen, Germany (haase@alpha.imib.rwth-aachen.de). Clinical Infectious Diseases 1999;29:120 – 4 © 1999 by the Infectious Diseases Society of America. All rights reserved. 1058 – 4838/99/2901– 0019$03.00 Case Report A 36-year-old man underwent surgery of the left lung in 1985 because of spontaneous pneumothorax. In 1987 he developed Crohn’s disease, and in 1990 he underwent a subtotal colectomy. He was treated continuously with mesalazine and temporarily with corticosteroids. Bilateral apical pleural fibrosis (right . left) and cavernous changes in the left apical region were first detected on a chest radiograph in December 1993. Despite a history of smoking 30 cigarettes per day since 1977, there was no evidence of chronic obstructive lung disease or prior pulmonary tuberculosis. Because of increased activity of the Crohn’s disease, 30 mg of methylprednisolone per day was administered between July and October 1995. In September recurrent coughing and night sweats occurred, leading to admittance to the hospital in December due to progressive deterioration (e.g., subfebrile temperature and loss of weight [5 kg over 4 months]). Radiological examinations revealed extensive infiltrative and fibrous opacification and additional cavernous changes in the upper lobe of the left lung (figure 1, left). Since the tuberculin skin reaction was positive and acid-fast rod-shaped bacteria were detected upon microscopic examination in five sputum specimens obtained on subsequent days, antituberculous therapy with isoniazid, rifampicin, ethambutol, and pyrazinamide was initiated. The cultivated slowly growing, scotochromogenic mycobacterium could be unequivocally identified as M. xenopi by determination of the signature sequence of both the 16S-rDNA and the dnaJ gene [29, 30]. With use of the radiometric BACTEC method (Becton Dickinson, Heidelberg, Germany) at 42°C (the optimal growth temperature for M. xenopi), drug-susceptibility testing showed susceptibility to rifampicin and streptomycin but revealed resistance to isoniazid, ethambutol, and pyrazinamide. Etests (AB Biodisk, Solna, Sweden) performed on Middlebrook 7H10 Downloaded from http://cid.oxfordjournals.org/ by guest on September 9, 2014 Isolation of Mycobacterium xenopi from the respiratory tract may indicate pneumonia, often clinically indistinguishable from tuberculosis. Resistance to the classic antituberculous drugs renders the treatment of these infections problematic. We report on a case of cavernous pneumonia caused by M. xenopi in a 36-year-old male with natural killer cell deficiency but without severe immunodeficiency. He was successfully treated with a novel triple-drug combination comprising clarithromycin, sparfloxacin, and rifabutin. An impressive subsequent regression of pathological pulmonary changes was observed, and mycobacteria could no longer be detected. The therapeutic potential of clarithromycin and sparfloxacin in the treatment of M. xenopi infections is discussed. CID 1999;29 (July) Pulmonary M. xenopi Infection 121 agar at 42°C revealed a very low MIC for clarithromycin (0.016 mg/L) and sparfloxacin (0.003 mg/L) but a high MIC of 6.0 mg/L for ciprofloxacin. HIV serology was negative. Mild leukocytosis (11,600 lymphocytes/mL), with 1,276 lymphocytes /mL detected before initiation of therapy, was due mainly to (1) a reduction of CD8/CD11b coexpressing suppressor T lymphocytes (STLs) and (2) a reduction of CD16/CD56 coexpressing NKCs. The number of CD41 T cells was normal. Because of the deficiency of STLs, the CD4/CD8 ratio and the ratio of CD81/CD11b2 cytotoxic T lymphocytes (CTLs) to STLs were elevated (table 1). At this time, the 3H-thymidine incorporation rate by the patient’s cultured lymphocytes was five times higher than that of healthy controls. The mitogens phytohemagglutinin and concanavalin A and the recall antigen zymosan increased the 3H-thymidine incorporation rate of these basally stimulated lymphocytes by a much lower factor in the patient than in healthy controls. Conversely, the 3H-thymidine incorporation by the patient’s lymphocytes increased dose-dependently after stimulation with tuberculin by up to 8 times the basal incorporation rate. After species identification and drug-susceptibility testing, the treatment was switched to an alternative triple-drug regimen in January 1996, involving daily doses of 500 mg of clarithromycin, 200 mg of sparfloxacin, and 300 mg of rifabutin. Smears became negative within 6 weeks, and a negative sputum culture was achieved within 3 months. The overall 12-month antibiotic treatment led to an impressive regression of the laboratory and radiological changes (table 1 and figure 1, right). All 3H-thymidine incorporation rates normalized, but numbers of NKCs and STLs remained as low as in the baseline tests (table 1). The drug regimen was tolerated well. Photosensitization, a well-known side effect of sparfloxacin, was managed by Table 1. Immunologic findings at the time of diagnosis and after cure of severe pulmonary infection due to Mycobacterium xenopi in a young man. Parameter Erythrocyte sedimentation rate (mm/h), 1 h/2 h C-reactive protein (mg/mL) Cells Leukocytes (/mL) Lymphocytes (/mL) B cells (/mL) T cells (CD31) (/mL) T helper cells (CD31/CD41) (/mL) CD4/CD8 cell ratio Suppressor/cytotoxic T lymphocytes (CD31/CD81) (/mL) Cytotoxic T lymphocytes (CD81/CD11b2) (/mL) Suppressor T lymphocytes (CD81/CD11b1) (/mL) Cytotoxic/suppressor cell ratio Natural killer cells (CD161/CD561) (/mL) Diagnosis: December 1995 Cure: February 1997 38/70 72 5/19 10 11,600 1,276 179 1,059 766 3.00 255 217 38 5.71 64 7,200 1,512 423 1,013 771 2.83 272 197 45 4.38 60 Normal range 5/10 ,7 4,600–7,100 1,600–2,400 200–400 1,100–1,700 700–1,100 1.0–1.5 500–900 ... ... ,3.0 200–400 Downloaded from http://cid.oxfordjournals.org/ by guest on September 9, 2014 Figure 1. CT scans of the lung of a young man with severe pulmonary infection due to Mycobacterium xenopi, from the time of diagnosis in November 1995 (left) and of cure in February 1997 (right) (window, 1900 HU [Hounsfield unit]; center, 2600 HU). At left, dense opacification with cavitary changes are visible. After therapy (right), scarring and thickening of the bronchial walls but no persisting inflammatory lesions were evident. 122 Schmitt, Schnitzler, et al. light protection. Activity of Crohn’s disease was controlled by mesalazine monotherapy. Because of the favorable clinical course, therapy was stopped after 12 months. No evidence of recurrence was found in the subsequent follow-up period (2 years). Discussion therapy is variable and difficult to predict, and no proven correlation with in vitro test results could be found [1, 10, 11]. Surgery therefore represents an important alternative to drug therapy for patients with localized pulmonary disease [10, 11, 32, 45]. The prophylactic and therapeutic efficacy of rifabutin and newer macrolides such as clarithromycin and azithromycin against nontuberculous mycobacteria has been convincingly demonstrated [46 –55]. Therefore, they are used in many combination regimens for nontuberculous mycobacterial infections, including those due to M. xenopi [50 –52]. In vitro findings have shown excellent activity of sparfloxacin against nontuberculous mycobacteria, including strains of M. xenopi [56, 57]. High tissue concentrations of sparfloxacin are achieved by oral administration [58]. Pronounced synergy between sparfloxacin and clarithromycin as well as rifabutin has been observed in vitro [55, 59]. MICs of sparfloxacin were much lower than those of ofloxacin, levofloxacin, and, as also seen in our case, ciprofloxacin [59 – 61], a finding indicating that sparfloxacin may be the most potent quinolone against susceptible mycobacteria [62]. The triple-drug combination of clarithromycin, rifabutin, and sparfloxacin used in the present case has not been reported so far for nontuberculous mycobacterial infections. However, successful treatment of an extrapulmonary infection with clarithromycin and sparfloxacin has recently been described [63]. Despite its photosensitization side effect, sparfloxacin may be a valuable drug for treatment of M. xenopi infections. Acknowledgments The authors thank Dr. E. C. Bo¨ttger for performing the 16S rDNA signature sequence determination and Sabine Ba¨tge for excellent technical assistance. References 1. American Thoracic Society. Diagnosis and treatment of disease caused by non-tuberculous mycobacteria. Am J Respir Crit Care Med 1997; 156(suppl):S1–25. 2. Woods GL, Washington JA. Mycobacteria other than Mycobacterium tuberculosis: review of microbiologic and clinical aspects. Rev Infect Dis 1987;9:275–94. 3. Wolinsky E. Nontuberculous mycobacteria and associated diseases. Am Rev Respir Dis 1979;119:107–59. 4. Wayne LG, Sramek HA. Agents of newly recognized or infrequently encountered mycobacterial diseases. Clin Microbiol Rev 1992;5:1–25. 5. Jiva TM, Jacoby HM, Weymouth LA, Kaminski DA, Portmore AC. Mycobacterium xenopi: innocent bystander or emerging pathogen? Clin Infect Dis 1997;24:226 –32. 6. Wolinsky E. Editorial response: is Mycobacterium xenopi an emerging pathogen? Clin Infect Dis 1997;24:233– 4. 7. Costrini AM, Mahler DA, Gross WM, et al. Clinical and roentgenographic features of nosocomial pulmonary disease due to Mycobacterium xenopi. Am Rev Respir Dis 1981;123:104 –9. Downloaded from http://cid.oxfordjournals.org/ by guest on September 9, 2014 M. xenopi was clearly proven to be the etiologic agent of the cavitary pulmonary changes found in the present case. The possibility of misidentification of M. xenopi as Mycobacterium celatum was unequivocally excluded [29 –31]. Because of the repeated isolation of M. xenopi and the exclusion of a simultaneous Mycobacterium tuberculosis infection, the diagnostic criteria for a nontuberculous infection were fulfilled [1]. The high reactivity of the patient’s lymphocytes to tuberculin could be explained by the well-known cross-reactivity in cases of M. xenopi infections [32]. However, an earlier infection with M. tuberculosis could not be definitively excluded. The long-term corticosteroid therapy certainly represents a risk for secondary infections [33], but the subset of CD4 T cells responsible for regulating the immune response to M. tuberculosis [34 –36] was not impaired; our patient had normal CD4 cell counts and a strong reaction to PPD. The CD8 T cell subpopulation involved in immune response to M. tuberculosis is the CD11b2 CTLs [36 – 41]. It is notable that in our patient the reduction of CD8 T cells was not due to the CTLs but to the T suppressor cells. NKCs are also known to contribute to the immune response to mycobacteria, mainly mediated by a T cell–independent IFN-g secretion [42]. In patients with active ileocecal Crohn’s disease, oral corticosteroids are known to cause a temporary suppression of activity in peripheral blood NKCs [43] by repression of the synthesis of perforin mRNA and granzyme A and reduced adhesion to target cells [44]. Therefore, in our patient temporary suppression of the NKC function by corticosteroids might have contributed to development of the M. xenopi infection. Despite the lack of clinical signs of obstructive lung disease, the presence of further pulmonary damage has to be assumed in view of the patient’s long-term nicotine abuse. Malnutrition (body mass index, 18.3 kg/m2) associated with Crohn’s disease might have been a further risk factor. 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