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Mycobacterial Infections in Wild Boars (Sus scrofa) from Southern Switzerland: Diagnostic Improvements, Epidemiological Situation and Zoonotic Potential
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  • Giovanni Ghielmetti,
  • Monika Hilbe,
  • Ute Friedel,
  • Chiara Menegatti,
  • Luca Bacciarini,
  • Roger Stephan,
  • Guido Bloemberg
Giovanni Ghielmetti
University of Zurich
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Monika Hilbe
Vetsuisse Faculty University of Zurich
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Ute Friedel
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Chiara Menegatti
Cantonal Veterinary Office
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Luca Bacciarini
Cantonal Veterinary Office
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Roger Stephan
Institute for Food Safety and Hygiene
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Guido Bloemberg
National Reference Center for Enteropathogenic Bacteria and Listeria
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Abstract

The occurrence of mycobacterial infections in different hosts and their implication as obligate or opportunistic pathogens remain mainly unclear. In addition to the well-known pathogenic members of the Mycobacterium tuberculosis - complex (MTBC), over 180 nontuberculous mycobacteria (NTM) species have been described. Although the large majority of the NTM are assumed to be non-pathogenic to most individuals, an increasing trend in NTM infections has been observed over the last decades. The reasons of such augmentation are probably more than one: improved laboratory diagnostics, an increasing number of immunocompromised patients and individuals with lung damage are some of the possible aspects. Mandibular lymph nodes of 176 hunted wild boars from the pre-Alpine region of Canton Ticino, Switzerland, were collected. Following gross inspection, each lymph node was subjected to culture and to an IS6110 based real-time PCR specific for MTBC members. Histology was performed of a selection of lymph nodes presenting gross visible lesions. Moreover, accuracy of matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry species identification was compared with sequence analysis of a combination of housekeeping genes. Mycobacteria of the MTBC were detected in five out of 176 wild boars (2.8%; CI95% 1.2 - 6.5) and were all confirmed to be Mycobacterium microti by molecular methods. In addition, based on the examined lymph nodes, NTM were detected in 57.4% (CI95% 50.0 – 64.5) of the wild boars originating from the study area. The 111 isolates belonged to 24 known species and three potentially undescribed Mycobacterium species. M. avium subsp. hominissuis thereby predominated (22.5%) and was found in lymph nodes with and without macroscopic changes. Overall, the present findings show that, with the exception of undescribed Mycobacterium species where identification was not possible (3.6%; 4/111), MALDI-TOF had a high concordance rate (90.1%; 100/111 isolates) to the sequence based reference method.

Peer review status:ACCEPTED

30 Mar 2020Submitted to Transboundary and Emerging Diseases
31 Mar 2020Submission Checks Completed
31 Mar 2020Assigned to Editor
01 Apr 2020Reviewer(s) Assigned
29 Apr 2020Review(s) Completed, Editorial Evaluation Pending
29 Apr 2020Editorial Decision: Revise Minor
12 May 20201st Revision Received
12 May 2020Assigned to Editor
12 May 2020Submission Checks Completed
12 May 2020Reviewer(s) Assigned
11 Jun 2020Review(s) Completed, Editorial Evaluation Pending
29 Jun 2020Editorial Decision: Revise Minor
29 Jun 20202nd Revision Received
30 Jun 2020Submission Checks Completed
30 Jun 2020Assigned to Editor
30 Jun 2020Reviewer(s) Assigned
02 Jul 2020Review(s) Completed, Editorial Evaluation Pending
02 Jul 2020Editorial Decision: Accept