Detection of Wood Mice (Apodemus sylvaticus) Carrying Non-Tuberculous Mycobacteria Able to Infect Cattle and Interfere with the Diagnosis of Bovine Tuberculosis.

Lucía Varela-Castro,Olalla Torrontegi,Iker A Sevilla,Marta Barral

doi:10.3390/microorganisms8030374

Abstract

Mycobacterial infections caused by the Mycobacterium tuberculosis complex (MTC) and non-tuberculous mycobacteria (NTM) are of great medical and veterinary relevance. The aim of this research was to study whether small mammals play a role in the epidemiology of mycobacterioses. Four samplings of 100 traps were performed in each of three cattle farms with previous history of tuberculosis or NTM between 2017 and 2018. A total of 108 animals belonging to seven species were trapped, classified, and necropsied, and tissues were submitted to microbiological and molecular methods for mycobacteria identification. The wood mouse (Apodemus sylvaticus) was the most abundant species (87%). No MTC was detected but six different NTM were identified (M. intracellulare, M. avium subsp. paratuberculosis, M. gordonae, M. celatum, M. fortuitum, and a not determined Mycobacterium sp.), showing a prevalence of 6.5%. No significant association was found between mycobacteria prevalence and the analyzed factors. Although a role in the epidemiology of MTC could not be attributed to small mammals, A. sylvaticus carries NTM that could be pathogenic or interfere with the diagnosis of tuberculosis. According to our results, there is a risk of NTM transmission at the wildlife–livestock interface through potential indirect contacts between small mammals and cattle.

Highlights

Aside from the agents responsible for leprosy, the genus Mycobacterium includes a large number of species that can be split into two main groups: the Mycobacterium tuberculosis complex (MTC) and non-tuberculous mycobacteria (NTM)
Studies researching the potential role of small mammals in the epidemiology of mycobacterial infections are lacking
To the best of our knowledge, this is the first reported survey searching for mycobacteria in small mammals present in Spanish cattle farms with a history of mycobacterioses

Summary

Introduction

Aside from the agents responsible for leprosy, the genus Mycobacterium includes a large number of species that can be split into two main groups: the Mycobacterium tuberculosis complex (MTC) and non-tuberculous mycobacteria (NTM). Several species of mycobacteria have been detected in wild and domestic animals [1,2], in humans [3], and in the environment, which could represent an important reservoir due to the species’ resistance to adverse factors and ubiquity [4]. Those species belonging to MTC are the most studied, since they are the causative agents of human and animal tuberculosis (TB). Mycobacterium fortuitum [2,11], or with the protection provided by the Bacillus Calmette Guerin (BCG) vaccination [12]

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