Spondylitis Due to Mycobacterium xenopi in a Human Immunodeficiency Virus Type 1-Infected Patient: Case Report and Review of the Literature
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微生物临床杂志 2005年第3期
Service de Maladies Infectieuses et Tropicales A
Service d'Anatomopathologie
Service de Rhumatologie
Service de Bacteriologie, Hpital Bichat-Claude Bernard, Paris, France
ABSTRACT
Nontuberculous mycobacterial infections are well known to occur in patients with human immunodeficiency virus infection. However, spondylitis due to mycobacteria other than Mycobacterium tuberculosis is uncommon. We report a case of biopsy- and culture-proven Mycobacterium xenopi spondylitis in an AIDS patient and discuss approaches to diagnosis and therapy. This case serves to highlight the potential pathogenic role of this usually environmental commensal organism in severely immunosuppressed AIDS patients and uncertainties in their management, given the scarce data on appropriate therapy for this organism.
CASE REPORT
A 42-year-old man was diagnosed with AIDS in 1998 when he presented with Pneumocystis carinii pneumonia. Over the next few years, he developed several other opportunistic infections, as he was not adherent to antiretroviral therapy. In August 2003, he was admitted for cellulitis on the right side of his face. On admission, neurological examination found static cerebellar syndrome associated with kinetic gait instability. No sensory or motor deficit was found. The rest of the physical results were normal. Laboratory studies revealed normal full blood count, except for lymphopenia. The CD4 T-lymphocyte count was 41/mm3. Renal function and hepatic biology were within the normal limits. Three blood cultures were negative. Cerebral computed tomography (CT) scan showed several bilateral cortical hypodensities of frontal and temporal regions without enhancing after contrast product injection. Cerebral magnetic resonance imaging (MRI) revealed T2-weighed images without enhancing after gadolinium injection in the same areas. Cerebrospinal fluid showed 1 white blood cell as well as a protein level of 0.62 g/liter and a glucose level of 3 mmol/liter (serum level, 5.8 mmol/liter), and cultures were negative. The patient received intravenous oxacillin and needed surgical drainage for a facial soft-tissue abscess. Oxacillin was continued for 10 days. A presumptive standard treatment regimen against Toxoplasma gondii encephalitis was started, considering neurological signs and intracerebral abnormalities during CT scan and MRI. Progress was satisfactory at first, but after 2 weeks our patient developed sudden flaccid paralysis of both legs with a T8 sensory level. MRI of the spine revealed signs of spondylitis at the T7 to T8 level, with a locally compressing epidural mass and an anterolateral paraspinal soft-tissue-associated inflammatory process. Transoesophageal echocardiography showed no signs of endocarditis. A CT-guided vertebral biopsy was performed. Gram and acid-fast stains showed no organism, and standard bacterial cultures were negative after 48 h. Histology of the specimen showed nonspecific inflammation. Supposing that Staphylococcus aureus could be responsible for T7 to T8 spondylitis given the recent history of facial cellulitis, rifampin (600 mg twice a day) and ofloxacin (400 mg twice a day) were started after oxacillin was discontinued. Retrospective studies with chest X-rays taken 2 months earlier showed loss of T7 to T8 vertebral disk height, and this suggested chronic installation of discovertebral abnormalities. Moreover, MRIs suggested a subacute to chronic process compatible with mycobacterial disease. No history of tuberculosis was found. A tuberculin skin test was negative. Nevertheless, quadruple antituberculous therapy was started, and isoniazid, pyrazinamide, and ethambutol were added to rifampin and ofloxacin. Complementary histologic studies performed on the earlier vertebral biopsy specimen revealed granulomatous inflammation with caseation. After 6 weeks, Mycobacterium xenopi was isolated from a vertebral biopsy specimen. The mycobacteria colony morphology was smooth, and growth characteristics disclosed a slow-growing mycobacterium with optimal growth speed at 42°C. Photoreactivity testing revealed a nonchromogen isolate. The suspicion of M. xenopi infection was confirmed with rRNA nucleic acid probe testing. Pyrazinamide and ofloxacin administrations were stopped. Treatment was changed from rifampin to isoniazid, ethambutol, clarithromycin, and rifabutin, considering eventual introduction of lopinavir/ritonavir-based highly active antiretroviral therapy. The patient's condition improved, with rapid regression of flaccid paralysis and disappearance of epidural mass on MRI 2 months after treatment was started.
M. xenopi vertebral osteomyelitis is rarely reported in the medical literature, even for deeply immunodepressed human immunodeficiency virus type 1 (HIV-1)-infected patients. The significance of the M. xenopi isolate in this case is confirmed by culture from a sterile site in the presence of histopathological findings compatible with mycobacterial infection. The evolution of illness was favorable after a treatment initially including classical quadruple antituberculous therapy (rifampin, isoniazid, pyrazinamide, and ethambutol) for presumed tuberculous osteomyelitis for 2 months and then changed to rifabutin, isoniazid, ethambutol, and clarithromycin after identification of M. xenopi.
M. xenopi was first described in 1959, when it was isolated from skin lesions of a toad (Xenopus laevis) (17). It is a slow-growing, nonchromogenic or scotochromogenic nontuberculous mycobacterium often considered to be a commensal or environmental contaminant. Improved culture techniques have led to an increasing number of M. xenopi isolates being identified in clinical specimens (4). Colonization of the respiratory tract is the most common explanation for isolation of M. xenopi (4, 6, 9). However, few cases of clinically significant infection due to M. xenopi have been reported, especially for patients with AIDS, generally with CD4 counts of less than 100 cells/mm3 (8, 11). Lungs are the more frequent site of infection. Juffermans et al. (8) had reported 22 cases of HIV-infected patients from whom M. xenopi was isolated. Isolation of M. xenopi from a pulmonary specimen was found in 16 cases (8). However, extrapulmonary disease and disseminated disease have rarely been described. El-Helou et al. (5) had reported 28 cases of HIV-infected patients from whom one or more isolates of M. xenopi had been recovered. M. xenopi was thought to be of clinical significance in seven patients (25%): three with bacteremia, three with pulmonary disease, and one with lymphadenitis (5).
M. xenopi vertebral infections have been described after discovertebral surgery, induced by contact with contaminated surgical instruments (2). In the absence of surgery, vertebral osteomyelitis has been reported for five non-HIV-infected patients and recently for one HIV-infected patient (3, 7, 10, 12, 14, 15). Clinical presentation is rather similar to that of M. tuberculosis vertebral infections, but clinical progression seems slower with M. xenopi infection. Astagneau et al. (2) reported 58 cases of M. xenopi spinal infections after discovertebral surgery. The mean time between discectomy and diagnosis was 5.6 years (2). In the case of M. xenopi osteomyelitis in an HIV-infected patient reported by Kulasegaram et al., the backache history had continued for 2 years (10). Diagnosis confirmation always required invasive techniques: CT-guided vertebral biopsies.
Optimal treatment for M. xenopi infection is not well established. In vitro susceptibility tests do not correlate with clinical response. The American Thoracic Society guidelines recommend isoniazid, rifabutin, and ethambutol, with or without streptomycin or clarithromycin, for 18 to 24 months (1). This type of infection can be difficult to treat, with a high relapse rate reported despite prolonged courses of antibiotics. A recent randomized trial compared rifampin, ethambutol, and isoniazid to rifampin and ethambutol for treatment of pulmonary disease caused by M. avium subsp. intracellulare, M. malmoense, or M. xenopi in HIV-negative patients (16). M. xenopi was isolated in 42 cases. Failure and relapse rate comparison showed significant difference in favor of the association of rifampin, ethambutol, and isoniazid (11 versus 22%; P = 0.03). The relapse and failure rates found in this study indicated much worse outcomes than those for M. tuberculosis. A retrospective study conducted with HIV-infected patients with M. xenopi pneumonia or bacteremia showed a high rate of mortality (66%) (5). Better regimens are needed. Ongoing studies evaluating macrolides and quinolones may offer alternative treatments (13).
In conclusion, this case illustrates the importance of strain identification in the case of vertebral osteomyelitis, especially in immunodepressed HIV-infected patients, because atypical mycobacteria, M. xenopi in particular, can be implicated. Strain identification has prognostic and therapeutic implications. Treatment should be adapted and prolonged.
REFERENCES
American Thoracic Society. 1997. Diagnosis and treatment of disease caused by non-tuberculous mycobacteria. Am. J. Respir. Crit. Care Med. 156(Suppl.):S1-S5.
Astagneau, P., N. Desplaces, V. Vincent, V. Chicheportiche, A. H. Botherel, S. Mangat, K. Lebascle, P. Leonard, J. C. Desenclos, J. Grosset, J. M. Ziza, and G. Brücker. 2001. Mycobacterium xenopi spinal infections after discovertebral surgery: investigation and screening of a large outbreak. Lancet 358:747-751.
Danesh-Clough, T., J. C. Theis, and A. van der Linden. 2000. Mycobacterium xenopi infection of the spine: a case report and literature review. Spine 25:626-628.
Donnabella, V., J. Salazar-Schicchi, S. Bonk, B. Hanna, and W. N. Rom. 2000. Increasing incidence of Mycobacterium xenopi at Bellevue Hospital. An emerging pathogen or a product of improved laboratory methods Chest 118:1365-1370.
El-Helou, P., A. Rachlis, I. Fong, S. Walmsley, A. Phillips, I. Salit, and A. E. Simor. 1997. Mycobacterium xenopi infection in patients with human immunodeficiency virus infection. Clin. Infect. Dis. 25:206-210.
Jiva, T. M., H. M. Jacoby, L. A. Weymouth, D. A. Kaminski, and A. C. Portmore. 1997. Mycobacterium xenopi: innocent bystander or emerging pathogen Clin. Infect. Dis. 24:226-232.
Jones, P. G., M. A. Schrager, and R. J. Zabransky. 1995. Pott's disease caused by Mycobacterium xenopi. Clin. Infect. Dis. 21:1352.
Juffermans, N. P., A. Verbon, S. A. Danner, E. J. Kuijper, and P. Speelman. 1998. Mycobacterium xenopi in HIV-infected patients: an emerging pathogen. AIDS 12:1661-1666.
Kerbiriou, L., A. Ustianowski, M. A. Johnson, S. H. Gillespie, R. F. Miller, and M. C. I. Lipman. 2003. Human immunodeficiency virus type 1-related pulmonary Mycobacterium xenopi infection: a need to treat Clin. Infect. Dis. 37:1250-1253.
Kulasegaram, R., D. Richardson, B. Macrae, and A. de Ruiter. 2001. Mycobacterium xenopi osteomyelitis in a patient on highly active antiretroviral therapy (HAART). Int. J. STD AIDS 12:404-406.
Manfredi, R., A. Nanetti, M. Tadolini, et al. 2003. Role of Mycobacterium xenopi disease in patients with HIV infection at the time of highly active antiretroviral therapy (HAART). Comparison with the pre-HAART period. Tuberculosis 83:319-328.
Miller, N. C., M. D. Perkins, W. J. Richardson, and D. J. Sexton. 1994. Pott's disease caused by Mycobacterium xenopi: case report and review. Clin. Infect. Dis. 19:1024-1028.
Ormerod, P. 2001. A step forward in the evidence-based treatment of opportunist mycobacteria. Thorax 56:163-165.
Prosser, A. J. 1986. Spinal infection with Mycobacterium xenopi. Tubercle 67:229-232.
Rahman, M. A., V. Phongsathom, T. Hughes, and C. Bielawska. 1992. Spinal infection by Mycobacterium xenopi in a non-immunosuppressed patient. Tuber. Lung Dis. 73:392-395.
Research Committee of the British Thoracic Society. 2001. First randomised trial of treatments for pulmonary disease caused by M. avium intracellulare, M. malmoense, and M. xenopi in HIV negative patients: rifampicin, ethambutol, and isoniazid versus rifampicin and ethambutol. Thorax 56:167-172.
Schwabacher, M. J. 1959. A strain of mycobacterium isolated from skin lesions of a cold-blooded animal, Xenopus laevis, and it relation to atypical acid-fast bacilli occurring in man. J. Hyg. 57:57-67.(Agnes Meybeck, Claude For)
Service d'Anatomopathologie
Service de Rhumatologie
Service de Bacteriologie, Hpital Bichat-Claude Bernard, Paris, France
ABSTRACT
Nontuberculous mycobacterial infections are well known to occur in patients with human immunodeficiency virus infection. However, spondylitis due to mycobacteria other than Mycobacterium tuberculosis is uncommon. We report a case of biopsy- and culture-proven Mycobacterium xenopi spondylitis in an AIDS patient and discuss approaches to diagnosis and therapy. This case serves to highlight the potential pathogenic role of this usually environmental commensal organism in severely immunosuppressed AIDS patients and uncertainties in their management, given the scarce data on appropriate therapy for this organism.
CASE REPORT
A 42-year-old man was diagnosed with AIDS in 1998 when he presented with Pneumocystis carinii pneumonia. Over the next few years, he developed several other opportunistic infections, as he was not adherent to antiretroviral therapy. In August 2003, he was admitted for cellulitis on the right side of his face. On admission, neurological examination found static cerebellar syndrome associated with kinetic gait instability. No sensory or motor deficit was found. The rest of the physical results were normal. Laboratory studies revealed normal full blood count, except for lymphopenia. The CD4 T-lymphocyte count was 41/mm3. Renal function and hepatic biology were within the normal limits. Three blood cultures were negative. Cerebral computed tomography (CT) scan showed several bilateral cortical hypodensities of frontal and temporal regions without enhancing after contrast product injection. Cerebral magnetic resonance imaging (MRI) revealed T2-weighed images without enhancing after gadolinium injection in the same areas. Cerebrospinal fluid showed 1 white blood cell as well as a protein level of 0.62 g/liter and a glucose level of 3 mmol/liter (serum level, 5.8 mmol/liter), and cultures were negative. The patient received intravenous oxacillin and needed surgical drainage for a facial soft-tissue abscess. Oxacillin was continued for 10 days. A presumptive standard treatment regimen against Toxoplasma gondii encephalitis was started, considering neurological signs and intracerebral abnormalities during CT scan and MRI. Progress was satisfactory at first, but after 2 weeks our patient developed sudden flaccid paralysis of both legs with a T8 sensory level. MRI of the spine revealed signs of spondylitis at the T7 to T8 level, with a locally compressing epidural mass and an anterolateral paraspinal soft-tissue-associated inflammatory process. Transoesophageal echocardiography showed no signs of endocarditis. A CT-guided vertebral biopsy was performed. Gram and acid-fast stains showed no organism, and standard bacterial cultures were negative after 48 h. Histology of the specimen showed nonspecific inflammation. Supposing that Staphylococcus aureus could be responsible for T7 to T8 spondylitis given the recent history of facial cellulitis, rifampin (600 mg twice a day) and ofloxacin (400 mg twice a day) were started after oxacillin was discontinued. Retrospective studies with chest X-rays taken 2 months earlier showed loss of T7 to T8 vertebral disk height, and this suggested chronic installation of discovertebral abnormalities. Moreover, MRIs suggested a subacute to chronic process compatible with mycobacterial disease. No history of tuberculosis was found. A tuberculin skin test was negative. Nevertheless, quadruple antituberculous therapy was started, and isoniazid, pyrazinamide, and ethambutol were added to rifampin and ofloxacin. Complementary histologic studies performed on the earlier vertebral biopsy specimen revealed granulomatous inflammation with caseation. After 6 weeks, Mycobacterium xenopi was isolated from a vertebral biopsy specimen. The mycobacteria colony morphology was smooth, and growth characteristics disclosed a slow-growing mycobacterium with optimal growth speed at 42°C. Photoreactivity testing revealed a nonchromogen isolate. The suspicion of M. xenopi infection was confirmed with rRNA nucleic acid probe testing. Pyrazinamide and ofloxacin administrations were stopped. Treatment was changed from rifampin to isoniazid, ethambutol, clarithromycin, and rifabutin, considering eventual introduction of lopinavir/ritonavir-based highly active antiretroviral therapy. The patient's condition improved, with rapid regression of flaccid paralysis and disappearance of epidural mass on MRI 2 months after treatment was started.
M. xenopi vertebral osteomyelitis is rarely reported in the medical literature, even for deeply immunodepressed human immunodeficiency virus type 1 (HIV-1)-infected patients. The significance of the M. xenopi isolate in this case is confirmed by culture from a sterile site in the presence of histopathological findings compatible with mycobacterial infection. The evolution of illness was favorable after a treatment initially including classical quadruple antituberculous therapy (rifampin, isoniazid, pyrazinamide, and ethambutol) for presumed tuberculous osteomyelitis for 2 months and then changed to rifabutin, isoniazid, ethambutol, and clarithromycin after identification of M. xenopi.
M. xenopi was first described in 1959, when it was isolated from skin lesions of a toad (Xenopus laevis) (17). It is a slow-growing, nonchromogenic or scotochromogenic nontuberculous mycobacterium often considered to be a commensal or environmental contaminant. Improved culture techniques have led to an increasing number of M. xenopi isolates being identified in clinical specimens (4). Colonization of the respiratory tract is the most common explanation for isolation of M. xenopi (4, 6, 9). However, few cases of clinically significant infection due to M. xenopi have been reported, especially for patients with AIDS, generally with CD4 counts of less than 100 cells/mm3 (8, 11). Lungs are the more frequent site of infection. Juffermans et al. (8) had reported 22 cases of HIV-infected patients from whom M. xenopi was isolated. Isolation of M. xenopi from a pulmonary specimen was found in 16 cases (8). However, extrapulmonary disease and disseminated disease have rarely been described. El-Helou et al. (5) had reported 28 cases of HIV-infected patients from whom one or more isolates of M. xenopi had been recovered. M. xenopi was thought to be of clinical significance in seven patients (25%): three with bacteremia, three with pulmonary disease, and one with lymphadenitis (5).
M. xenopi vertebral infections have been described after discovertebral surgery, induced by contact with contaminated surgical instruments (2). In the absence of surgery, vertebral osteomyelitis has been reported for five non-HIV-infected patients and recently for one HIV-infected patient (3, 7, 10, 12, 14, 15). Clinical presentation is rather similar to that of M. tuberculosis vertebral infections, but clinical progression seems slower with M. xenopi infection. Astagneau et al. (2) reported 58 cases of M. xenopi spinal infections after discovertebral surgery. The mean time between discectomy and diagnosis was 5.6 years (2). In the case of M. xenopi osteomyelitis in an HIV-infected patient reported by Kulasegaram et al., the backache history had continued for 2 years (10). Diagnosis confirmation always required invasive techniques: CT-guided vertebral biopsies.
Optimal treatment for M. xenopi infection is not well established. In vitro susceptibility tests do not correlate with clinical response. The American Thoracic Society guidelines recommend isoniazid, rifabutin, and ethambutol, with or without streptomycin or clarithromycin, for 18 to 24 months (1). This type of infection can be difficult to treat, with a high relapse rate reported despite prolonged courses of antibiotics. A recent randomized trial compared rifampin, ethambutol, and isoniazid to rifampin and ethambutol for treatment of pulmonary disease caused by M. avium subsp. intracellulare, M. malmoense, or M. xenopi in HIV-negative patients (16). M. xenopi was isolated in 42 cases. Failure and relapse rate comparison showed significant difference in favor of the association of rifampin, ethambutol, and isoniazid (11 versus 22%; P = 0.03). The relapse and failure rates found in this study indicated much worse outcomes than those for M. tuberculosis. A retrospective study conducted with HIV-infected patients with M. xenopi pneumonia or bacteremia showed a high rate of mortality (66%) (5). Better regimens are needed. Ongoing studies evaluating macrolides and quinolones may offer alternative treatments (13).
In conclusion, this case illustrates the importance of strain identification in the case of vertebral osteomyelitis, especially in immunodepressed HIV-infected patients, because atypical mycobacteria, M. xenopi in particular, can be implicated. Strain identification has prognostic and therapeutic implications. Treatment should be adapted and prolonged.
REFERENCES
American Thoracic Society. 1997. Diagnosis and treatment of disease caused by non-tuberculous mycobacteria. Am. J. Respir. Crit. Care Med. 156(Suppl.):S1-S5.
Astagneau, P., N. Desplaces, V. Vincent, V. Chicheportiche, A. H. Botherel, S. Mangat, K. Lebascle, P. Leonard, J. C. Desenclos, J. Grosset, J. M. Ziza, and G. Brücker. 2001. Mycobacterium xenopi spinal infections after discovertebral surgery: investigation and screening of a large outbreak. Lancet 358:747-751.
Danesh-Clough, T., J. C. Theis, and A. van der Linden. 2000. Mycobacterium xenopi infection of the spine: a case report and literature review. Spine 25:626-628.
Donnabella, V., J. Salazar-Schicchi, S. Bonk, B. Hanna, and W. N. Rom. 2000. Increasing incidence of Mycobacterium xenopi at Bellevue Hospital. An emerging pathogen or a product of improved laboratory methods Chest 118:1365-1370.
El-Helou, P., A. Rachlis, I. Fong, S. Walmsley, A. Phillips, I. Salit, and A. E. Simor. 1997. Mycobacterium xenopi infection in patients with human immunodeficiency virus infection. Clin. Infect. Dis. 25:206-210.
Jiva, T. M., H. M. Jacoby, L. A. Weymouth, D. A. Kaminski, and A. C. Portmore. 1997. Mycobacterium xenopi: innocent bystander or emerging pathogen Clin. Infect. Dis. 24:226-232.
Jones, P. G., M. A. Schrager, and R. J. Zabransky. 1995. Pott's disease caused by Mycobacterium xenopi. Clin. Infect. Dis. 21:1352.
Juffermans, N. P., A. Verbon, S. A. Danner, E. J. Kuijper, and P. Speelman. 1998. Mycobacterium xenopi in HIV-infected patients: an emerging pathogen. AIDS 12:1661-1666.
Kerbiriou, L., A. Ustianowski, M. A. Johnson, S. H. Gillespie, R. F. Miller, and M. C. I. Lipman. 2003. Human immunodeficiency virus type 1-related pulmonary Mycobacterium xenopi infection: a need to treat Clin. Infect. Dis. 37:1250-1253.
Kulasegaram, R., D. Richardson, B. Macrae, and A. de Ruiter. 2001. Mycobacterium xenopi osteomyelitis in a patient on highly active antiretroviral therapy (HAART). Int. J. STD AIDS 12:404-406.
Manfredi, R., A. Nanetti, M. Tadolini, et al. 2003. Role of Mycobacterium xenopi disease in patients with HIV infection at the time of highly active antiretroviral therapy (HAART). Comparison with the pre-HAART period. Tuberculosis 83:319-328.
Miller, N. C., M. D. Perkins, W. J. Richardson, and D. J. Sexton. 1994. Pott's disease caused by Mycobacterium xenopi: case report and review. Clin. Infect. Dis. 19:1024-1028.
Ormerod, P. 2001. A step forward in the evidence-based treatment of opportunist mycobacteria. Thorax 56:163-165.
Prosser, A. J. 1986. Spinal infection with Mycobacterium xenopi. Tubercle 67:229-232.
Rahman, M. A., V. Phongsathom, T. Hughes, and C. Bielawska. 1992. Spinal infection by Mycobacterium xenopi in a non-immunosuppressed patient. Tuber. Lung Dis. 73:392-395.
Research Committee of the British Thoracic Society. 2001. First randomised trial of treatments for pulmonary disease caused by M. avium intracellulare, M. malmoense, and M. xenopi in HIV negative patients: rifampicin, ethambutol, and isoniazid versus rifampicin and ethambutol. Thorax 56:167-172.
Schwabacher, M. J. 1959. A strain of mycobacterium isolated from skin lesions of a cold-blooded animal, Xenopus laevis, and it relation to atypical acid-fast bacilli occurring in man. J. Hyg. 57:57-67.(Agnes Meybeck, Claude For)