Clostridium tetani growth and toxin production in the intestines of germfree rats

Vaccine Production to Protect Animals Against Pathogenic Clostridia

Clostridium is a broad genus of anaerobic, spore-forming, rod-shaped, Gram-positive bacteria that can be found in different environments all around the world. The genus includes human and animal pathogens that produce potent exotoxins that cause rapid and potentially fatal diseases responsible for countless human casualties and billion-dollar annual loss to the agricultural sector. Diseases include botulism, tetanus, enterotoxemia, gas gangrene, necrotic enteritis, pseudomembranous colitis, blackleg, and black disease, which are caused by pathogenic Clostridium. Due to their ability to sporulate, they cannot be eradicated from the environment. As such, immunization with toxoid or bacterin-toxoid vaccines is the only protective method against infection. Toxins recovered from Clostridium cultures are inactivated to form toxoids, which are then formulated into multivalent vaccines. This review discusses the toxins, diseases, and toxoid production processes of the most common pathogenic Clostridium species, including Clostridiumbotulinum, Clostridiumtetani, Clostridiumperfringens, Clostridiumchauvoei, Clostridiumsepticum, Clostridiumnovyi and Clostridiumhemolyticum.

Risk-based immunization policies and tuberculosis screening practices for animal care and research workers in the United States: survey results and recommendations

A national survey was conducted to assess immunization practices and tuberculosis screening methods for animal care and research workers in biomedical settings throughout the United States. Veterinarians (n = 953) were surveyed via a web-based mechanism; completed surveys (n = 308) were analyzed. Results showed that occupational health and safety programs were well-developed, enrolling veterinary, husbandry, and research staff at rates exceeding 90% and involving multiple modalities of health assessments and risk communication for vaccine-preventable diseases. Most (72.7%) institutions did not store serum samples from animal research personnel. More than half of the institutions housed nonhuman primates and maintained tuberculosis screening programs, although screening methods varied. Immunization protocols included various recommended or required vaccines that differed depending on job duties, type of institution, and nature of scientific programs. A single case of an identified vaccine-preventable illness in a laboratory worker was noted. Tetanus toxoid was the predominant vaccine administered (91.7%) to animal care and research workers, followed by hepatitis B (54.8%), influenza (39.9%), and rabies (38.3%). For some immunization protocols, an inconsistent rationale for administration was evident. Indications that animal care and research workers are unprotected from work-related etiologic agents did not emerge from this survey; rather, existing guidelines from the Advisory Committee on Immunization Practices and available biologics seem sufficient to address most needs of the laboratory animal research community. Institutions should commit to performance-based standards in parallel with context-specific risk assessment methods to maintain occupational health and safety programs and practices appropriate to their needs.

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

Clostridial infections are found worldwide in almost all species of animals and may involve a variety of body systems and present with a diversity of clinical signs. Most damage done through clostridial infections is due to the action of toxins released from the bacteria.Thus, disease caused by Clostridium spp should more correctly be called intoxication. Two prominent clostridial infections are associated with neurologic signs: Clostridium botulinum and C tetani. In both infections, the mechanism that is responsible for causing the problem is similar, despite the remarkable difference in clinical presentation. In addition, neurologic signs are described with C perfringens types C and D but are not the dominant feature of these diseases.

Autism and Clostridium tetani

Autism is a severe developmental disability believed to have multiple etiologies. This paper outlines the possibility of a subacute, chronic tetanus infection of the intestinal tract as the underlying cause for symptoms of autism observed in some individuals. A significant percentage of individuals with autism have a history of extensive antibiotic use. Oral antibiotics significantly disrupt protective intestinal microbiota, creating a favorable environment for colonization by opportunistic pathogens. Clostridium tetani is an ubiquitous anaerobic bacillus that produces a potent neurotoxin. Intestinal colonization by C. tetani, and subsequent neurotoxin release, have been demonstrated in laboratory animals which were fed vegetative cells. The vagus nerve is capable of transporting tetanus neurotoxin (TeNT) and provides a route of ascent from the intestinal tract to the CNS. This route bypasses TeNT's normal preferential binding sites in the spinal cord, and therefore the symptoms of a typical tetanus infection are not evident. Once in the brain, TeNT disrupts the release of neurotransmitters by the proteolytic cleavage of synaptobrevin, a synaptic vesicle membrane protein. This inhibition of neurotransmitter release would explain a wide variety of behavioral deficits apparent in autism. Lab animals injected in the brain with TeNT have exhibited many of these behaviors. Some children with autism have also shown a significant reduction in stereotyped behaviors when treated with antimicrobials effective against intestinal clostridia. When viewed as sequelae to a subacute, chronic tetanus infection, many of the puzzling abnormalities of autism have a logical basis. A review of atypical tetanus cases, and strategies to test the validity of this paper's hypothesis, are included.

Antibacterial immunity and its modeling in experimental tumor tetanus and wound tetanus of the mouse

The experimental and theoretical analysis of the tumor-tetanus phenomenon has provided us with new insights into the pathogenesis of tetanus infection. Our theoretical model of clostridial propagation in the proliferating tissue is based upon the principle of mitosis-controlled rod division (hit and cloning model). It has lent itself to the description of early growth stages of the clostridial rod population in our experiments of tumor tetanus and of wound tetanus of the mouse. However, the later course of the tetanus lethality curves under antitoxin protection, about a week following injection of the tumor cell-spore or CaCl2-spore suspensions, reveals a pronounced delay in clostridial propagation. Based on our model we can explain this process by a humoral immune reaction directed against the clostridial rods taking into account the variability of elimination of the heterologous tetanus antitoxin applied. The experimental results are in good agreement with those obtained by computer simulation. The theoretical knowledge resulting from these studies can be used for the interpretation of the serodiagnostic tumor test with apathogenic clostridia as well as for the quantitative assessment of the malignancy of neoplastic growth.