Nontuberculous Mycobacteria in Freshwater Fish and Fish Products Intended for Human Consumption

Abstract

Nontuberculous mycobacteria (NTM) are potentially pathogenic agents commonly found in natural ecosystems, while food is considered to be another source of NTM for humans. We investigated a total of 92 tissue samples of freshwater fish and fish products: fish directly obtained from ponds (n=25), retail fresh (n=23) and frozen fish (n=23) and smoked fish products (n=21). Culture examination for the presence of mycobacteria was positive in 11 (11.9%) from all the examined samples. The 15 obtained isolates were identified as Mycobacterium fortuitum (n=5), M. immunogenum (n=2), M. phocaicum/ mucogenicum (n=1), M. neoaurum (n=2), M. peregrinum (n=2), M. porcinum (n=1) and M. senegalense/houstonense/conceptionense (n=2). NTM DNA was found in one (4.0%) sample of fresh fish from ponds and in 60.9% and 91.3% of retail fresh and frozen fish, respectively. None of the smoked fish products contained NTM DNA. The results of our study suggest that freshwater fish and fish products, especially retail frozen fish, might be a reservoir of NTM for humans, and proper handling and treatment before consumption of such products is recommended.

Global Environmental Nontuberculous Mycobacteria and Their Contemporaneous Man-Made and Natural Niches

“…While not considered a food-borne illness, M. avium subspecies DNA was also identified in raw meats (Lorencova et al, 2014). In contrast, smoked fish products did not show NTM, but 12% of samples collected from pond fish (4%), retail sold fish (61%), and frozen fish (91%) contained NTM DNA (Lorencova et al, 2013). Although unproven, the acid-resistant NTM organisms may remain viable in the stomach where food is consumed and digested.…”

Draft Genome Sequence of Mycobacterium porcinum CSURP1564

“… M. porcinum is indistinguishable from the closely related Mycobacterium conceptionense on the sole basis of 16S rRNA gene sequence analysis but could be identified by partial rpoB gene sequencing ( 2 , 3 ). M. porcinum has been detected in various environments, including drinking water ( 4 , 5 ), fish, and fresh vegetables for human consumption ( 6 , 7 ). M. porcinum is known to infect wild and domestic animals ( 8 ) and exhibits a zoonotic potential, being isolated from bovine milk ( 9 ).…”

Draft Genome Sequence of Mycobacterium houstonense Strain ATCC 49403 T

“…M. houstonense is represented by only two isolates from human sources in the United States, including one face wound isolate from Houston, TX, hence the name given to this species ( 1 ). Accordingly, the sources of human infection remain unknown, but sequences closely related to those of M. houstonense have been detected in consumed fishes ( 2 ). Moreover, M. houstonense is one of the nontuberculous Mycobacterium species containing the erm gene, which supports resistance to macrolides ( 3 ).…”