Affiliations: Department of Biochemistry, Lady Hardinge Medical
College and Associated Hospitals, New Delhi, India | Department of Biotechnology, All India Institute of
Medical Sciences, New Delhi, India | Department of Microbiology, Lady Hardinge Medical
College and Associated Hospitals, New Delhi, India | Department of Pediatrics, Lady Hardinge Medical
College and Associated Hospitals, New Delhi, India
Note: [] Correspondence: Dr. Bimota Nambam, MD, Senior Resident,
Biochemistry, Lady Hardinge Medical College and Associated Hospitals, New
Delhi-110001, India. Tel.: +9891089132; E-mail: [email protected]
Abstract: Tuberculous meningitis, an extrapulmonary manifestation of
tuberculosis, is associated with poor prognosis and high mortality in the
pediatric age group with delayed treatment. The main causative agent in humans
is Mycobacterium tuberculosis but other members of the M.
tuberculosis complex especially Mycobacterium bovis, have also been
implicated as potential human pathogens. Our study utilizes the hup B
gene (Rv2986c in M. tuberculosis and Mb3010c in M.
bovis) as a target for a two-step 'in house' nested polymerase chain reaction
(PCR) in cerebrospinal fluid samples and can differentiate between M.
tuberculosis and M. bovis. The products obtained for M.
tuberculosis and M. bovis are 116 and 89 base pair respectively due to a
27 base pair deletion at the C-terminal of hup B gene of M. bovis.
Fifty cases, suggestive of tuberculous meningitis, and fifty controls (admitted
for other causes) were chosen as per Modified Ahuja's criteria and correlated
with response to therapy. They were regrouped retrospectively as definitive
tuberculous meningitis [25] and non-tuberculous meningitis [75]. Of the
non-tuberculous meningitis category, 45 patients were diagnosed as pyogenic
meningitis while the rest were diagnosed as febrile seizures [16],
hypocalcemic seizures [11] and enteric encephalopathy [3]. Mycobacterial
DNA extracted from cerebrospinal fluid samples were subjected to a two-step
nested PCR. A sensitivity of 92% and specificity of 98.7% was obtained.
M. tuberculosis and M. bovis infection was seen in 56% and 35%
of the PCR positive cases respectively while 9% showed co-infection with
both species. Thus this novel gene target shows promising potential as a rapid
molecular diagnostic aid in pediatric tuberculous meningitis where rapid
institution of antituberculosis therapy is essential.
Keywords: Polymerase chain reaction, M. tuberculosis, M. bovis, tuberculous meningitis, cerebrospinal fluid
