Vol. 10, Special Issue 12 (2021)

Author(s):
Jawahar A, Dhinakar Raj G, Pazhanivel N, Manoharan S, Vijayarani K and Sarathchandra G

Abstract:
A study was conducted to assess the respiratory excretion pattern of Mycobacterium species organisms from tuberculin skin test reactor cattle and buffaloes. Nasal secretions (n=33), milk samples (n=10) and prescapular lymph node aspirates (PSLA) (n=20) were collected from reactor animals and inoculated in BACTECTM Mycobacteria growth indicator tubes (MGITTM) culture system. Ziehl Neelsen (ZN) staining of BACTEC positive samples revealed presence of acid fast organisms in nasal secretions (24.2%), milk samples (20%) and PSLA (15%). Polymerase chain reaction (PCR) for IS6110 gene revealed that no sample was positive for the presence of genome of Mycobacterium tuberculosis complex (MTBC) organisms. PCR with 16S rRNA detected presence of non-tuberculosis Mycobacteria (NTM) in 21.2% of nasal secretions, 20% of milk samples and 15% of PSLA collected. The earlier and rapid growth of NTM in the culture probably overwhelmed the growth of MTBC, which was confirmed in in-vitro growth curve experiments. Thus, the presence of NTM in the nasal secretions and other samples may mask the growth of MTBC; hence it could not be detected in the samples collected. This study concluded that the nasal swabbing may not be an ideal method for isolation of MTBC organisms from reactor animals wherein NTMs are abundantly present and post mortem tissue samples may be the appropriate source for MTBC isolation, in such samples.