Indian Journal of Medical Sciences Medknow Publications on behalf of Indian Journal of Medical Sciences Trust ISSN: 0019-5359 EISSN: 1998-3654 Vol. 58, Num. 5, 2004, pp. 203-205

Indian Journal of Medical Science Vol. 58 No. 5, May, 2004, pp. 203-205

CASE REPORT

SPINAL TUBERCULOSIS DUE TO DISSEMINATION OF ATYPICAL MYCOBACTERIA

BITHIKA DUTTAROY, CHARU AGRAWAL, ANIRUDDHA PENDSE

Departments of Microbiology and Orthopaedics, Medical College and Sir Sayaji General Hospital, Baroda, Gujarat, India.
Correspondence: Dr. Bithika Duttaroy, 806, Bhagyoday Tower 1, Pashabhai Park, Race Course, Baroda- 390 007, India. E-mail: charuap@yahoo.com

Code Number: ms04036

ABSTRACT

There has been an increase in disease caused by Non Tuberculous Mycobacteria (NTM) since the early 1980s. Though ubiquitous in environment, they may act as clinically important pathogens in various conditions. More importantly they are resistant to the conventional anti-tuberculous therapy (ATT) and respond to antibiotics such as quinolones and aminoglycosides and need an aggressive surgical intervention. Missing these atypical mycobacteria may lead to unnecessary administration of ATT and hence delay in proper management of the case. We report a case of spinal tuberculosis due to a Non Tuberculous Mycobacteria, M. fortuitum (Rapid grower). Relevant literature is also reviewed.

Key Words: Tuberculous spine, Non tuberculous mycobacteria (NTM), Mycobacterium fortuitum.

INTRODUCTION

For decades the "Atypical" tuberculosis like organisms isolated occasionally from the patients were considered contaminants or transient colonizers. With the development of newer techniques for the diagnosis as well as effective chemotherapy for Mycobacterium tuberculosis, the role of these organisms in causing human disease has been highlighted.¹ A better terminology for these atypical organisms, which has gained a wider acceptance, is Non tuberculous mycobacteria (NTM)¹. The NTM, ubiquitous in environment, gain access to the body through respiratory tract, gastro-intestinal tract and direct inoculation in skin and soft tissue. They can affect both immunocompetent and immunocompromised individuals, however dissemination of NTM is seen more in immunosuppressed individuals.¹ They have been implicated as the cause of bone and joint disease. Clinically there is little to differentiate this disease from tuberculosis.² We report a case of disseminated spinal tuberculosis due to an NTM on the basis of clinicoradiological back ground with microbiological findings.

CASE REPORT

A 42 yrs. old female presented with complaints of loss of sensations and inability to move both lower limbs. She also had low backache and low-grade fever for one week prior to admission. There was no history of trauma or diabetes mellitus. Patient was severely malnourished with a poor general condition. Back and spine examination revealed lower back gibbus and mild tenderness over T_7-8 with a local swelling. There were occasional crepitations in both lungs. There was a loss of tone, complete loss of power and sensation in the lower limbs. A clinical diagnosis of the tuberculous spine involving T_7-8 with paraplegia and anesthesia below L₁ without bladder and bowel involvement was arrived at. X-ray spine revealed collapse of T_7-8 vertebrae with a para-vertebral soft tissue shadow Chest X ray showed radio opaque patches in both lungs with a small cavity in right lower zone. An HIV testing turned out to be negative by ELISA. Sputum sample on Ziehl-Neelsen staining (ZN staining) showed presence of large number of pus cells along with pleomorphic acid fast bacilli (AFB) ranging from short rods to long filamentous forms, having a beaded appearance. Branching was not seen. Gram's staining of the sample showed Gram-positive short and long filamentous structures with beaded appearance but no branching. Sample was inoculated on MacConkey Agar without crystal violet and on Blood agar (BA). Colonies appeared after 72 hrs. On MacConkey agar the colonies were smooth, entire, moist, dome shaped & slightly pink in color while on BA tiny round colonies were seen. Urease test³ and 68⁰ catalase test³ were found to be positive. The clinician did not carry out the aspiration at local site for investigative purpose due to risk of spinal cord injury. The patient, who was initially started on anti-tuberculous treatment, put on gentamicin and ciprofloxacin. The patient responded to the antibiotic therapy but unfortunately was lost to follow up.

DISCUSSION

Spinal tuberculosis often involves two or more adjacent vertebral bodies.⁴ Lower thoracic and upper lumbar vertebrae are usually affected in adults.⁴ With advancement, the affected vertebral bodies may collapse resulting in kyphosis or a gibbus formation.⁴ A paravertebral abscess may also form.³ A catastrophic complication of spinal tuberculosis is development of paraplegia either due to an abscess or a lesion compressing on the spinal cord.⁴ Although the diagnosis of musculo-skeletal tuberculosis is based on clinical and radiological findings, etiological confirmation is based on bacteriological studies. Based on the microscopic findings and cultural characteristics, we tentatively identified our isolate to be M.fortuitum (Rapid Grower). The most common organism under this group is the Mycobacterium-fortuitum-chelonae complex, also known as the M.fortuitum complex.⁵ Microscopically in Acid fast stain preparations, M.fortuitum cells are generally pleomorphic, ranging from long filamentous forms to short thick rods, sometimes beaded in appearance, but branching is typically absent.⁵ On Gram's staining, they appear as short or long filamentous faintly staining Gram positive bacilli having the capability to grow on Mac conkey agar, without crystal violet, forming smooth dome shaped colonies with slight pigment production⁵. Growth is also seen within 72 hrs. on routine 5% sheep blood agar appearing as tiny pin point colonies.⁵ Further confirmation of the M.fortuitum is evidenced by a positive Aryl Sulfatase test at 3 days, a positive urease test, positive 68⁰ catalase test, positive nitrate reduction test, iron uptake and tolerance to 5% sodium chloride^{3, 6, 7}. A positive urease test and a positive 68⁰ catalase test identified our isolate to be the M.fortuitum. Unfortunately antibiotic susceptibility testing could not be carried out due to lack of facilities. Environmental samples including tap water from the ward did not yield any positive mycobacterial culture. Atypical infections require much more aggressive surgical intervention because of lack of sensitivity and risk of progression with standard anti-tuberculous drugs^{7, 8}. The NTMs usually respond to antibiotics like quinolones, aminoglycosides etc.^6,7. The clinical manifestations and aggressive surgical treatment of atypical tuberculous spinal infection and mycobacterium infection are similar⁸.

Although a wide variety of infections are associated with M.fortuitum involving the lungs, skin, bone, CNS, prosthetic heart valves, and disseminated disease, we did not come across any reported case of spinal tuberculosis due to dissemination of M.fortuitum. This was rather an uncommon case of spinal tuberculosis due to M.fortuitum probably disseminated from a primary infection in lungs. Nevertheless the microbiologist must be alert to the possibility of it being a causative organism and not merely a contaminant. A lack of suspicion in this regard may lead to a needless and prolonged administration of conventional ATT, in turn leading to prolonged suffering for the patient.  

REFERENCE

1. Shinners D, Yeager H, Jr. In: Schlossberg David, editor. Tuberculosis and Non Tuberculous Mycobacterium Infections. 4^th ed. Philadelphia: W. B. Saunders; 1999. p. 341
2. Davidson PT, Quoc Hanh Le. In: Schlossberg David, editor. Tuberculosis and Non Tuberculous Mycobacterium Infections. 4^th ed. Philadelphia: W. B. Saunders; 1999. p. 215
3. Forbes AB, Sahm FD, Weissfeld SA. Bailey and Scott's Diagnostic Microbiology: 11^th ed. Philadelphia: Mosby; 2002. p. 556-61.
4. Raviglione MC, O'Brien RJ. In: Fauci AS, Braunwald E, Isselbacher KJ, Wilson JD, Martin JB, Kasper DL, et al. editors. Harrison's Principles of Internal Medicine, 14^th ed. New York: Mc Graw-Hill; 1998. p. 1008.
5. Koneman EW, Allen SD, Janda WM, Schreckenberger PC, Winn Washington C Jr. Colour Atlas and Text book of Diagnostic Microbiology: 5^th ed. Philadelphia: Lippincott; 1997. p. 933.
6. Sethi S, Sharma M, Ray P, Singh M, Gupta A. Mycobacterium fortuitum wound infection following laparoscopy. Indian J Med Res 2000;113:83-4.
7. Satyanarayana S, Mathur AD. Atypical Mycobacterial injection abscess. J Indian Med Assoc 2003;101:36-40.
8. Wood GW II. In: Terry Canale S, editor. Campbell's Operative Orthopedics, 10^th ed. St. Louis: Mosby; 2003. p. 2044.

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