Thermal Inactivation of Mycobacterium avium subsp. paratuberculosis in Artificially Contaminated Milk by Direct Steam Injection

Abstract

The efficiency of direct steam injection (DSI) at 105°C for 3 s to inactivate Mycobacterium avium subsp. paratuberculosis in milk at a pilot-plant scale was investigated. Milk samples were artificially contaminated with M. avium subsp. paratuberculosis and also with cow fecal material naturally infected with M. avium subsp. paratuberculosis. We also tested milk artificially contaminated with Mycobacterium smegmatis as a candidate surrogate to compare thermal inactivation between M. smegmatis and M. avium subsp. paratuberculosis. Following the DSI process, no viable M. avium subsp. paratuberculosis or M. smegmatis was recovered using culture methods for both strains. For pure M. avium subsp. paratuberculosis cultures, a minimum reduction of 5.6 log 10 was achieved with DSI, and a minimum reduction of 5.7 log 10 was found with M. smegmatis. The minimum log 10 reduction for wild-type M. avium subsp. paratuberculosis naturally present in feces was 3.3. In addition, 44 dairy and nondairy powdered infant formula (PIF) ingredients used during the manufacturing process of PIF were tested for an alternate source for M. avium subsp. paratuberculosis and were found to be negative by quantitative PCR (qPCR). In conclusion, the results obtained from this study indicate that a >7-fold-log 10 reduction of M. avium subsp. paratuberculosis in milk can be achieved with the applied DSI process. IMPORTANCEM. avium subsp. paratuberculosis is widespread in dairy herds in many countries. M. avium subsp. paratuberculosis is the causative agent of Johne's disease in cattle, and infected animals can directly or indirectly (i.e., fecal contamination) contaminate milk. Despite much research and debate, there is no conclusive evidence that M. avium subsp. paratuberculosis is a zoonotic bacterium, i.e., one that causes disease in humans. The presence of M. avium subsp. paratuberculosis or its DNA has been reported in dairy products, including pasteurized milk, cheese, and infant formula. In light of this, it is appropriate to evaluate existing mitigation measures to inactivate M. avium subsp. paratuberculosis in dairy products. The work conducted in this study describes the efficacy of direct steam injection, a thermal process commonly used in the dairy industry, to eliminate M. avium subsp. paratuberculosis and a surrogate bacterium in milk, thus ensuring the absence of M. avium subsp. paratuberculosis in dairy products subject to these process conditions. M ycobacterium avium subsp. paratuberculosis is a well-known animal pathogen that causes Johne's disease (JD), also known as paratuberculosis, in cattle. JD has a global occurrence and is widely prevalent among dairy herds (1). Besides the negative impact on animal health and welfare and being the cause of economic losses, e.g., due to reduced milk production, M. avium subsp. paratuberculosis has also been suggested to be the causative agent of Crohn's disease in humans (2). It has been proposed that milk contaminated with M. avium subsp. paratuberculosis might act as a source of ...

Estimation of Performance Characteristics of Analytical Methods for Mycobacterium avium subsp. paratuberculosis Detection in Dairy Products

“…Four reference strains of MAP (ATCC 19851; ATCC 43015; DSM 44133; and DSM 44135), were used to spike the test portions. Each freeze-dried MAP strain was grown as described by Peterz et al (2016) to produce the reference and working stocks.…”

Bovine Colostrum for Human Consumption—Improving Microbial Quality and Maintaining Bioactive Characteristics through Processing

“…paratuberculosis (MAP) causes paratuberculosis in cows. Paratuberculosis is also referred to as Johne's disease and characterized as being a chronic granulomatous infection of ruminant intestines [81], presenting an economic burden for the dairy industry [82]. Both colostrum and milk act as potential transfer routes in spreading the disease among cattle.…”

“…The shedding of the bacteria by infected cows mainly happens through feces, but it can also be excreted in colostrum [83]. Besides the threat for bovine health, a likely connection between MAP and Crohn's disease in humans is suspected, but not proven, to be of zoonotic risk [81,82]. In humans, MAP can also cause tuberculosis infection [62,83].…”

Bovine Colostrum for Human Consumption - Improving Microbial Quality and Maintaining Bioactive Characteristics through Processing

“…paratuberculosis (MAP) is causing paratuberculosis in cows. Paratuberculosis is also referred to as Johne's disease and characterized being a chronic granulomatous infection of ruminant intestines [81], presenting an economic burden for the dairy industry [82]. Both colostrum and milk act as potential transfer routes in spreading the disease among cattle.…”