Clostridial disease associated with neurologic signs: tetanus, botulism, and enterotoxemia

Successful treatment of idiopathic tetanus using metronidazole, magnesium, and acepromazine in Hanwoo (Korean indigenous cattle) yearling bull

Bovine tetanus is a serious infectious disease of the central nervous system caused by the exotoxin produced by Clostridium tetani and is characterized by persistent tension and spasm of the rhabdomyocytes. Currently, many studies have focused on diagnosing tetanus; however, only a few studies on treatment methods have been conducted. Therefore, cattle with tetanus have been treated using symptomatic therapy. In this case, severe muscle spasticity and spasms were observed in a 9-month-old Hanwoo (Korean indigenous cattle) bull, and aspartate aminotransferase and creatine kinase levels were increased in serum biochemical tests. Clinically, bovine tetanus was strongly suspected, and metronidazole was administered orally for 5 days. To treat the intensifying bloat, a temporary rumenostomy was performed on the third day of onset, and the toxin gene (tetanospasmin) of C. tetani was amplified by polymerase chain reaction analysis from the collected ruminal fluid. Magnesium and sedatives (acepromazine) were administered for 7 days to treat muscle spasticity and spasms. Muscle spasticity and spasm markedly improved, and the bull stood up from the lateral recumbent position. On the 17^th day after onset, all tetanus-related symptoms resolved and a normal diet was started. Our findings demonstrated that treatment with metronidazole, magnesium, and acepromazine was effective in the bull with tetanus.

Inhibition of Virulence Gene Expression in Salmonella Dublin, Escherichia coli F5 and Clostridium perfringens Associated With Neonatal Calf Diarrhea by Factors Produced by Lactic Acid Bacteria During Fermentation of Cow Milk

Diarrhea is a major health problem in neonatal and young calves worldwide. It can be caused by a variety of infectious agents, including the bacteria Salmonella enterica serovar Dublin (S. Dublin), enterotoxigenic Escherichia coli (ETEC), and Clostridium perfringens. Preventive alternatives to antibiotic treatment should be identified. As a first step toward this, the aim of the current study was to examine whether cell-free supernatants from cow milk fermented by lactic acid bacteria affects virulence-gene expression in strains of S. Dublin, ETEC E. coli F5 and C. perfringens. pH-neutralized, cell-free, spent medium of milk (nCFSM) fermented by 61 different lactic acid bacteria (LAB) and non-LAB starter cultures belonging to 17 genera was assayed for their effect on expression of important virulence factors (S. Dublin hilA, ssrB, ssaG, flhD, prgI, fliC; ETEC E. coli F5 fanC, estA, fim41a; C. perfringens cpa), when the bacteria were grown in the nCFSM. Screening was done using either a promoter-reporter expression system or RT-qPCR. nCFSM from Bifidobacterium longum BL-15955 and Limosilactobacillus reuteri LR-33016 downregulated the expression of fanC, fim41a and estA genes in the four tested ETEC E. coli F5 strains without affecting their growth, while mainly B. longum BL-15955 downregulated expression of cpa in the four tested strains of C. perfringens. nCFSM from the mixed cultures; NU-TRISH^® BY-Mild (Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and Bifidobacterium BL-15954) and COMBO4 (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus), as well as Lactobacillus helveticus CNRZ32 downregulated the tested virulence genes in the three tested strains of S. Dublin. To enable possible downregulation of the expression of virulence genes in all three target bacteria simultaneously, nCFSM was prepared from NU-TRISH^® By-Mild in combination with B. longum BL-15955 (i.e. a four-strain combination). The nCFSM from this combination downregulated the virulence genes expression in all the three species. In the future, NU-TRISH^® By-Mild and B. longum BL-15955 in combination could potentially be used for prevention of neonatal calf diarrhea caused by S. Dublin, E. coli F5, and C. perfringens, reducing the need for antimicrobial treatment, however, field studies are needed to prove that.

A Sarcina bacterium linked to lethal disease in sanctuary chimpanzees in Sierra Leone

Human and animal infections with bacteria of the genus Sarcina (family Clostridiaceae) are associated with gastric dilation and emphysematous gastritis. However, the potential roles of sarcinae as commensals or pathogens remain unclear. Here, we investigate a lethal disease of unknown etiology that affects sanctuary chimpanzees (Pan troglodytes verus) in Sierra Leone. The disease, which we have named "epizootic neurologic and gastroenteric syndrome" (ENGS), is characterized by neurologic and gastrointestinal signs and results in death of the animals, even after medical treatment. Using a case-control study design, we show that ENGS is strongly associated with Sarcina infection. The microorganism is distinct from Sarcina ventriculi and other known members of its genus, based on bacterial morphology and growth characteristics. Whole-genome sequencing confirms this distinction and reveals the presence of genetic features that may account for the unusual virulence of the bacterium. Therefore, we propose that this organism be considered the representative of a new species, named "Candidatus Sarcina troglodytae". Our results suggest that a heretofore unrecognized complex of related sarcinae likely exists, some of which may be highly virulent. However, the potential role of "Ca. S. troglodytae" in the etiology of ENGS, alone or in combination with other factors, remains a topic for future research.

Cryptosporidium parvum and other enteric pathogens in scouring neonatal dairy calves from the Al Ain region, United Arab Emirates

Faecal specimens from 36 scouring neonatal calves from two dairy farms located in the Al Ain region of the UAE were screened with pathogen-specific antigen ELISA for Cryptosporidium parvum, Escherichia coli K99, rotavirus, and coronavirus. Additionally, faecal smears were stained with modified-acid-fast for Cryptosporidium oocysts, and the VITEK 2 system plus Gram's stain used to identify bacteria isolated from the faecal samples. Farm management practices were also evaluated during a farm visit. Of the 36 calves, 29, 13, 5, and 6 were positive for C. parvum, E. coli K99, bovine coronavirus, and rotavirus antigens respectively, while 27 were positive for Cryptosporidium oocysts. In various combinations, mixed infections were detected in 20/36 calves. This is the first report of C. parvum, E. coli K99, Salmonella spp., rotavirus, and coronavirus in ≤14-days-old scouring neonatal dairy calves from the UAE. Molecular characterization of these pathogens and nationwide epidemiological calf scour studies are recommended.

Development and biochemical and immunological characterization of early passage and immortalized bovine intestinal epithelial cell lines from the ileum of a young calf

The intestinal epithelium is a major site of interaction with pathogens. In bovine intestinal epithelial cells (BIECs), Toll-like receptors (TLRs) play an important role in innate immune responses against enteric pathogens. This study is aimed at establishing a stable bovine intestinal epithelial cell line that can be maintained by a continuous passage so that studies on innate immune responses against various enteric pathogens can be performed. The main goal was to establish pure cultures of primary and immortalized bovine intestinal epithelial cells from the ileum and then characterize them biochemically and immunologically. Mixed epithelial and fibroblast bovine ileal intestinal cultures were first established from a 2-day old calf. Limiting dilution method was used to obtain a clone of epithelial cells which was characterized using immunocytochemistry (ICC). The selected clone BIEC-c4 was cytokeratin positive and expressed low levels of vimentin, confirming the epithelial cell phenotype. Early passage BIEC-c4 cells were transfected with either simian virus 40 (SV40) large T antigen or human telomerase reverse transcriptase (hTERT), or human papillomavirus (HPV) type 16E6/E7 genes to establish three immortalized BIEC cell lines. The expression of SV40, hTERT and HPV E6/E7 genes in immortalized BIECs was confirmed by a polymerase chain reaction (PCR). Immunocytochemistry and immunofluorescence assays also confirmed the expression of SV40, hTERT and HPV E6 proteins. The immortalized BIECs were cytokeratin positive and all except HPV-BIECs expressed low levels of vimentin. A growth kinetics study indicated that there were no significant differences in the doubling time of immortalized BIECs as compared to early passage BIEC-c4 cells. All four BIEC types expressed TLR 1-10 genes, with TLR 3 and 4 showing higher expression across all cell types. These newly established early passage and immortalized BIEC cell lines should serve as a good model for studying infectivity, pathogenesis and innate immune responses against enteric pathogens.

Evidence for a natural humoral response in dairy cattle affected by persistent botulism sustained by non-chimeric type C strains

Bovine botulism is a sporadic acute disease that usually causes catastrophic losses in the herds. The unusual clinical evolution of a persistent mild outbreak in a dairy herd, prompted us to characterize the neurotoxin gene profile of the strain involved and to evaluate whether seroconversion had occurred. Diagnosis was based on mild classical symptoms and was supported by PCR and bacteriological findings, which revealed the involvement of a non-mosaic type C strain. An in-house ELISA was developed to detect antibodies to botulinum neurotoxin type C and its performance was evaluated in a vaccination study. Fifty days after the index case, fecal and serum samples were collected from the 14 animals of the herd and screened for Clostridium botulinum and anti-botulinum neurotoxin antibodies type C, respectively. The in-house developed ELISA was also used to test 100 sera samples randomly collected from 20 herds. Strong ELISA reactions were observed in 3 convalescent and 5 asymptomatic animals involved in the studied outbreak. The ELISA-positive cows all tested positive for non-mosaic C. botulinum type C in the feces and the same strain was also detected in the alfalfa hay, suspected to be the carrier source. Ten out of the 100 randomly collected sera tested positive for anti-botulinum neurotoxin type C antibodies: 7 had borderline values and 3 from the same herd showed titers three times higher than the cut-off. We concluded that type C botulism in cattle may occur with variable severity and that prolonged exposure to sublethal doses of botulinum neurotoxin C may occur, resulting in detectable antibodies.

An overview of calf diarrhea - infectious etiology, diagnosis, and intervention

Calf diarrhea is a commonly reported disease in young animals, and still a major cause of productivity and economic loss to cattle producers worldwide. In the report of the 2007 National Animal Health Monitoring System for U.S. dairy, half of the deaths among unweaned calves was attributed to diarrhea. Multiple pathogens are known or postulated to cause or contribute to calf diarrhea development. Other factors including both the environment and management practices influence disease severity or outcomes. The multifactorial nature of calf diarrhea makes this disease hard to control effectively in modern cow-calf operations. The purpose of this review is to provide a better understanding of a) the ecology and pathogenesis of well-known and potential bovine enteric pathogens implicated in calf diarrhea, b) describe diagnostic tests used to detect various enteric pathogens along with their pros and cons, and c) propose improved intervention strategies for treating calf diarrhea.

ClosTron-mediated engineering of Clostridium

Members of the genus Clostridium are of both medical and industrial importance. The molecular tools necessary to study and exploit their wide ranging physiological diversity through directed mutational analysis have until recently been lacking. The situation was transformed in the mid-2000s with the specific adaptation of intron re-targeting technology to the genus, through the development of the ClosTron. By making a handful of nucleotide changes to the group II intron encoding region, the intron can be directed to insert into almost any region within the genome. Through the use of a retrotransposition-activated marker (RAM), based on the ermB gene, successful insertion is selected on the basis of acquisition of resistance to erythromycin. The re-targeted region is designed using an online re-targeting algorithm (www.clostron.com), and then an order is placed with DNA2.0 for both the synthesis of the re-targeted region and its custom cloning into the ClosTron vector. Re-targeted ClosTrons are delivered ready for use in 10–14 days, allowing mutants to be isolated 5–7 days after receipt. Its availability has revolutionized clostridial molecular biology.

Clostridial toxins

Clostridia produce the highest number of toxins of any type of bacteria and are involved in severe diseases in humans and other animals. Most of the clostridial toxins are pore-forming toxins responsible for gangrenes and gastrointestinal diseases. Among them, perfringolysin has been extensively studied and it is the paradigm of the cholesterol-dependent cytolysins, whereas Clostridium perfringens epsilon-toxin and Clostridium septicum alpha-toxin, which are related to aerolysin, are the prototypes of clostridial toxins that form small pores. Other toxins active on the cell surface possess an enzymatic activity, such as phospholipase C and collagenase, and are involved in the degradation of specific cell-membrane or extracellular-matrix components. Three groups of clostridial toxins have the ability to enter cells: large clostridial glucosylating toxins, binary toxins and neurotoxins. The binary and large clostridial glucosylating toxins alter the actin cytoskeleton by enzymatically modifying the actin monomers and the regulatory proteins from the Rho family, respectively. Clostridial neurotoxins proteolyse key components of neuroexocytosis. Botulinum neurotoxins inhibit neurotransmission at neuromuscular junctions, whereas tetanus toxin targets the inhibitory interneurons of the CNS. The high potency of clostridial toxins results from their specific targets, which have an essential cellular function, and from the type of modification that they induce. In addition, clostridial toxins are useful pharmacological and biological tools.