Mycobacterium fortuitum abortion in a sow

Abstract

Two aborted Chester White pig fetuses were presented to a veterinary diagnostic laboratory in Illinois. Postmortem examination identified no gross abnormalities. Histologic evaluation revealed multifocal necrosis of chorionic epithelial cells, coalescing areas of mineralization in the placenta, and focal accumulations of viable and degenerate neutrophils in the lung. Intra- and extracellular acid-fast bacilli were identified in the lesions in both the placenta and lungs. Bacterial culture of stomach contents yielded heavy growth of Mycobacterium fortuitum, a rapidly growing nontuberculous mycobacterium (NTM), which was further confirmed through whole-genome sequencing. NTM are opportunistic pathogens commonly found in the soil and in contaminated water supplies. In animals, M. fortuitum is typically introduced through cutaneous wounds leading to infections limited to the skin, with systemic infection being uncommon. To our knowledge, abortion caused by M. fortuitum has not been reported previously.

Keywords: Mycobacterium fortuitum; abortion; nontuberculous mycobacteria; swine.

Figures 1–4.

Mycobacterium fortuitum abortion in a sow. Bar = 20 µm. Figure 1. Multifocal necrosis of chorionic epithelial cells with neutrophils and macrophages in placenta. H&E. Figure 2. Bronchioles and alveoli of fetal lung filled with viable and degenerate neutrophils and few macrophages. H&E. Figure 3. Intracytoplasmic and extracellular acid-fast bacteria in the placenta. Fite acid-fast stain. Figure 4. Intrahistiocytic acid-fast bacilli in the lung. Fite acid-fast stain.

Figure 5.

Phylogenetic tree analysis of A. 16 ribosomal RNA sequence and B. whole-genome sequence–based single-nucleotide variation of mycobacterium isolates including the IL2019 isolate marked with a red square, GenBank accession, and country information.