Clostridium are spore forming bacteria that are ubiquitous in fecal and environmental dairy samples. Toxin-producing clostridium species such as C. perfringens, C. septicum, and C. difficile have been associated with enteric disease in ruminants.

Researchers J.S. Thompson, A.H. Smith, M.N. Griffin, T.L. March, R.F. Teal, V.G. Bretl, R.R. Geier and T.G. Rehberger of Arm & Hammer, Waukesha, Wis., have conducted a survey aimed at characterizing clostridium populations in dairies across the U.S. in order to better understand the species richness, evenness and determine if regional differences exist in Clostridium populations.

The survey was conducted from November 2015 to February 2019. In total, 14,265 fecal samples were collected from 368 farms across 26 states. Samples were transported on ice to the lab within 24 hours and clostridia were enumerated on TSC agar incubated under anaerobic conditions. Counts ranged from < 1.0E1 to 1.5E8 cfu/g total clostridia with a mean of 9.2E4 cfu/g and median of 6.4E2 cfu/g.

Clostridia isolates were collected from a core set of more than 4,000 fecal samples to identify toxin types. Over half (52.6%) of the isolates (n =52,322) tested from cow samples were identified as C. perfringens. Calf clostridia isolates (n = 6,219) had a lower percentage identified as toxin-producing C. perfringens (38.9%) than cows. In both cows and calves, C. perfringens isolates were mainly Type A (99.0%).

Non-C. perfringens isolates were identified using 16S PCR. The 2 most abundant species were identified as C. bifermentans group (14.4%) and C. beijerinckii group (8.6%). These species are known for their ability to produce end products such as 1,3 propanediol, butanol and acetone, the researchers noted.

Twenty-eight species of clostridium were detected including other toxin-producing species such as C. sordellii and C. difficile. Clostridium populations were analyzed based on region. Samples collected from California, Texas, Upper Midwest and Wisconsin had different populations (P < 0.05) compared with Idaho, Great Lakes, Mid Atlantic, Florida, I-29 Corridor and Northeast; the Northeast trended toward having a different clostridium population (P = 0.09).

In presenting their results at the American Dairy Science Assn. annual meeting, the researchers noted that the data gives a better understanding of clostridium species in ruminants and demonstrates regional clostridia population differences across the U.S.