Comparative evaluation of egg based solid media for primary isolation of Paratuberculosis bacilli

Abstract

Paratuberculosis caused by Mycobacterium avium subspecies paratuberculosis (MAP) is a prevalent infection and is highly expensive to livestock industry. Paratuberculosis also has zoonotic concerns with Crohn’s disease. Isolation of MAP from infected individuals/samples is the most vital for downstream studies. However, MAP is extremely fastidious organism and primary isolation is extremely difficult. Mycobacterial growth indicator tube (MGIT) medium is most recommended for primary isolation, but this medium is highly expensive and requires sophisticated instrument and is unaffordable for developing and underdeveloped world. Present study aimed to investigate the comparative performance of three different egg based solid media (MB7H10, LJ and HEYM) for the primary isolation of MAP from clinically suspected animals. Animals having signs of paratuberculosis were sampled either from farms in Jaipur District of Western India or slaughterhouse. Slaughtered animals were sampled having swollen & enlarged mesenteric lymph nodes (MLN) with thickened/ corrugated intestine near ileo-cecal junction (ICJ). Fecal samples were collected from suspected cattle, buffalo, goat and sheep. MB7H10 medium showed maximum recovery of MAP isolates from clinical samples. Most of the isolates grew on MB7H10 (41.9 %) followed by LJ (22.3%) and HEYM (6.25 %). In case single medium is to be used MB7H10 is the first choice and combination of MB7H10+LJ is better. In conclusion, combination of MB7H10+LJ is the best choice for solid media for the isolation of the MAP in laboratories.