Public health relevance of non-tuberculous mycobacteria among AFB positive sputa.
BACKGROUND
Sputum smear microscopy for acid fast bacilli (AFB) is used by most public health programmes to detect tuberculosis. While most AFB in countries endemic for tuberculosis areMycobacterium tuberculosis(MTB), some may also be non-tuberculous mycobacteria (NTM). The inability to differentiate NTM from MTB by sputum smear microscopy may lead to erroneous diagnoses of tuberculosis, leading in turn to inappropriate therapy.


METHODS
This was a retrospective study of consecutive sputum samples received from November 2013 to March 2015 in the Department of Microbiology, Bhopal Memorial Hospital & Research Centre, Bhopal, India. Samples underwent smear microscopy, line probe assay (LPA) for MTB complex, culture, biochemical tests and LPA for NTM.


RESULTS
Of 4095 sputum samples, 2886 were AFB smear positive (70.5%). Of these, MTB complex was detected in 2611 (90.5%) samples by LPA. Of the remaining 275 samples, 47 grew AFB on culture. Nine strains belonged to the MTB complex. The remaining 38 (1.3%) were NTM, and could be speciated in 26 strains; 14 (53.8 %) wereM. abscessus; 10 (38.4%)M. intracellulare, one (3.8%)M. kansasiiand one (3.8%)M. fortuitum. The remaining 12 NTM could not be speciated.


CONCLUSIONS
NTM were present in at least 1.3% of all smear positive samples. It is important for public health programs to recognize the avoidable burden on logistics, infrastructure and finances caused by this. Detection and quantification of this burden would help design an appropriate strategy for optimal tuberculosis control.
MD, Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038, India.
Prabha
P
Desikan
MD, Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038, India.
Karuna
K
Tiwari
MSc, Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038, India.
Nikita
N
Panwalkar
MSc, Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038, India.
Saima
S
Khaliq
BSc, Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038, India.
Manju
M
Chourey
MSc, Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038, India.
Reeta
R
Varathe
MSc, Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038,India.
Shaina Beg
SB
Mirza
MSc, Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038, India.
Arun
A
Sharma
PhD, Consultant Microbiologist, World Health Organization, Central TB Division, Ministry of Health & Family Welfare (Government of India), Nirman Bhawan, 523 'C' Wing, New Delhi, 110 011, India.
Sridhar
S
Anand
MS, Department of Oncology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal, 462038, India.MSc, Department of Microbiology, St. John's Medical College Hospital, Bengaluru, Karnataka, India.
Manoj
M
Pandey
Acid fast bacilli; microscopy; non-tuberculous mycobacteria; tuberculosis