Necrotizing hepatitis caused by Clostridium novyi type B in a dog with no predisposing liver lesions: a case report

BACKGROUND

Infectious necrotic hepatitis (INH) is typically a disease of ruminants caused by Clostridium novyi type B. Growth of the causative agent is supported by development of an anaerobic environment within the liver. In dogs, C. novyi is rare and has only been previously reported as a post-mortem diagnosis. In one case, infection was secondary to metastatic pancreatic adenocarcinoma and the other was presumptively diagnosed on histopathology of a hepatic lesion in a dog initially presented for acute collapse.

CASE PRESENTATION

An 8-year-old spayed, female mixed breed dog was presented for acute onset of hyporexia and vomiting. Serum biochemistry revealed elevated hepatocellular injury and cholestatic liver enzymes. Ultrasound revealed peritoneal fluid accumulation and multiple hepatic masses. Cytologic examination of liver aspirates and peritoneal fluid revealed frequent 4 × 1 μm bacilli with a terminal endospore. Anaerobic bacterial growth isolated from the fluid sample could not be identified using typical laboratory identification techniques. Long-read, whole genome sequencing was performed, and the organism was identified as Clostridium novyi type B. Antimicrobial and hepatic support treatment were initiated. The patient re-presented 27 days later, and the follow up liver aspirate with cytology revealed no appreciable bacteria and anaerobic culture was negative. The patient was presented four months later and a large hepatic mass and peritoneal fluid were again identified on abdominal ultrasound. Cytologic examination of the peritoneal fluid revealed bacilli similar to those identified on initial presentation. The patient was euthanized. The most significant finding on necropsy was necrotizing hepatitis with intralesional endospore-forming bacilli compatible with recurrence of Clostridium novyi type B. There was no identifiable cause of an anaerobic insult to the liver.

CONCLUSIONS

This case demonstrates the diagnostic utility of using cytology as part of the initial diagnostic work up for infectious hepatitis. The cytologic findings coupled with whole genome sequencing and anaerobic culture were crucial for the identification and classification of the organism identified on fine needle aspirate. Clostridium novyi type B should be considered when bacilli organisms containing a terminal endospore are identified on liver aspirates collected from canine patients.

Combined Molecular and Biochemical Identification of Alpha Toxin in Local Isolated Clostridium novyi from the Sheep Liver

Clostridium novyi (C. novyi) causes deadly Black disease in sheep and rarely in other animals. Alpha toxin (α-toxin), the most apparent pathogen of this disease, is produced by C. novyi type B. Economic damages of C. novyi include sheep mortality costs, depreciation of affected farms, and health problems with infected carcasses. The identification of C. novyi and isolation of its pathogens by conventional methods is a time-consuming process, necessitating a simple and rapid method for isolating and detecting pathogenic C. novyi. Therefore, this study aimed to molecularly identify α-toxin in local C. novyi isolates from the sheep livers. In this study, 75 livers suspected of Black disease were sampled. The samples of the liver were cultured under anaerobic conditions. Some of the cultured colonies were used in biochemical tests. For molecular confirmation, the DNA of isolates was extracted, and the isolates were confirmed by the polymerase chain reaction (PCR) on the liver tissue and cultured samples using specific α-toxin primers. The PCR on α-toxin produced a band in the range of 609 bp, indicating that the samples belonged to C. novyi. According to the results, of 75 isolates, 18 isolates were confirmed as C. novyi. C. novyi type B was isolated from the liver and confirmed by biochemical and molecular characterization. The PCR assay ensured a sensitive and specific tool for the detection of C. novyi in the samples.

The oncolytic activity of Clostridium novyi nontoxic spores in breast cancer

Introduction: Hypoxia context is highly specific for tumors and represents a unique niche which is not found elsewhere in the body. Clostridium novyi is an obligate anaerobic bacterium. It has a potential to treat tumors. The aim of this study was to produce the C. novyi nontoxic spores and to investigate its oncolytic effect on breast cancer in mice model. Methods: Primarily, the lethal toxin gene in C. novyi type B was removed. Colonies were isolated using PCR testing. To assure the removal of alpha-toxin, plasmid extraction and in vivo assay were conducted. Next, to treat breast cancer model in different sizes of tumors, a single dose of spores of C. novyi nontoxic was tested. Results: The results denoted that C. novyi nontoxic lost lethal toxin and a--ppeared to be safe. For smaller than 1000 mm³ tumors, a single dose of C. novyi nontoxic was able to cure 100% of mice bearing breast tumors. Hence the mice remained free of tumor relapse. Tumors larger than 1000 mm³ were not cured by a single dose- of C. novyi nontoxic treatment. Conclusion: The experiment concluded that the C. novyi nontoxic might be a suitable and safe candidate, a novel therapeutic approach to encounter such hypoxic regions in the center of tumors. Research also showed that bacteriolytic therapy by C. novyi nontoxic could lead to regression in small tumor.

O-acetylhomoserine sulfhydrylase from Clostridium novyi. Cloning, expression of the gene and characterization of the enzyme

The gene NT01CX_1210 of pathogenic bacterium Clostridium novyi annotated as encoding O-acetylhomoserine sulfhydrylase was cloned and expressed in Escherichia coli. The gene product having O-acetylhomoserine sulfhydrylase activity was purified to homogeneity. The protein showed molecular mass of approximately 184 kDa for the native form and 46 kDa for the subunit. The enzyme catalyzes the γ-substitution reaction of O-acetylhomoserine with maximum activity at pH 7.5. Analysis of C. novyi genome allowed us to suggest that there is only one way for the synthesis of l-methionine in the bacterium. The data obtained may provide the basis for further study of the role of OAHS in Clostridium bacteria and an ascertainment of its mechanism.

Characterization of Clostridium novyi isolated from a sow in a sudden death case in Korea

Background

Multifocal spherical nonstaining cavities and gram-positive, rod-shaped, and endospore-forming bacteria were found in the liver of a sow that died suddenly. Clostridium novyi type B was identified and isolated from the sudden death case, and the isolate was characterized by molecular analyses and bioassays in the current study.

Results

C. novyi was isolated from the liver of a sow that died suddenly and was confirmed as C. novyi type B by differential PCR. The C. novyi isolate fermented glucose and maltose and demonstrated lecithinase activity, and the cell-free culture supernatant of the C. novyi isolate exhibited cytotoxicity toward Vero cells, demonstrating that the isolate produces toxins. In addition, whole-genome sequencing of the C. novyi isolate was performed, and the complete sequences of the chromosome (2.29 Mbp) and two plasmids (134 and 68 kbp) were identified for the first time. Based on genome annotation, 7 genes were identified as glycosyltransferases, which are known as alpha toxins; 23 genes were found to be related to sporulation; 12 genes were found to be related to germination; and 20 genes were found to be related to chemotaxis.

Conclusion

C. novyi type B was isolated from a sow in a sudden death case and confirmed by biochemical and molecular characterization. Various virulence-associated genes were identified for the first time based on whole-genome sequencing.

Hepatic gas gangrene caused by Clostridium novyi

We report the case of a patient with advanced gastric cancer and multiple liver metastases, who presented with bacteremia and hepatic gas gangrene caused by Clostridium novyi (C. novyi). The gas gangrene caused abscesses to form within metastatic lesions. This case highlights the antitumor effects of C. novyi in human.

The Contribution of Bacteriophages to the Biology and Virulence of Pathogenic Clostridia

Bacteriophages are key players in the evolution of most bacteria. Temperate phages have been associated with virulence of some of the deadliest pathogenic bacteria. Among the most notorious cases, the genes encoding the botulinum neurotoxin produced by Clostridium botulinum types C and D and the α-toxin (TcnA) produced by Clostridium novyi are both encoded within prophage genomes. Clostridium difficile is another important human pathogen and the recent identification of a complete binary toxin locus (CdtLoc) carried on a C. difficile prophage raises the potential for horizontal transfer of toxin genes by mobile genetic elements. Although the TcdA and TcdB toxins produced by C. difficile have never been found outside the pathogenicity locus (PaLoc), some prophages can still influence their production. Prophages can alter the expression of several metabolic and regulatory genes in C. difficile, as well as cell surface proteins such as CwpV, which confers phage resistance. Homologs of an Agr-like quorum sensing system have been identified in a C. difficile prophage, suggesting that it could possibly participate in cell-cell communication. Yet, other C. difficile prophages contain riboswitches predicted to recognize the secondary messenger molecule c-di-GMP involved in bacterial multicellular behaviors. Altogether, recent findings on clostridial phages underline the diversity of mechanisms and intricate relationship linking phages with their host. Here, milestone discoveries linking phages and virulence of some of the most pathogenic clostridial species will be retraced, with a focus on C. botulinum, C. novyi, C. difficile, and Clostridium perfringens phages, for which evidences are mostly available.

Optimization of the Production of Inactivated Clostridium novyi Type B Vaccine Using Computational Intelligence Techniques

Clostridium novyi causes necrotic hepatitis in sheep and cattle, as well as gas gangrene. The microorganism is strictly anaerobic, fastidious, and difficult to cultivate in industrial scale. C. novyi type B produces alpha and beta toxins, with the alpha toxin being linked to the presence of specific bacteriophages. The main strategy to combat diseases caused by C. novyi is vaccination, employing vaccines produced with toxoids or with toxoids and bacterins. In order to identify culture medium components and concentrations that maximized cell density and alpha toxin production, a neuro-fuzzy algorithm was applied to predict the yields of the fermentation process for production of C. novyi type B, within a global search procedure using the simulated annealing technique. Maximizing cell density and toxin production is a multi-objective optimization problem and could be treated by a Pareto approach. Nevertheless, the approach chosen here was a step-by-step one. The optimum values obtained with this approach were validated in laboratory scale, and the results were used to reload the data matrix for re-parameterization of the neuro-fuzzy model, which was implemented for a final optimization step with regards to the alpha toxin productivity. With this methodology, a threefold increase of alpha toxin could be achieved.

View from the front lines: an emergency medicine perspective on clostridial infections in injection drug users

Injection drug use (IDU), specifically non-intravenous "skin-popping" of heroin, seems to provide optimal conditions for Clostridial infection and toxin production. IDU is therefore a major risk factor for wound botulism and Clostridial necrotizing soft tissue infections (NSTI) and continues to be linked to cases of tetanus. Case clusters of all 3 diseases have occurred among IDUs in Western U.S. and Europe. Medical personnel who care for the IDU population must be thoroughly familiar with the clinical presentation and management of these diseases. Wound botulism presents with bulbar symptoms and signs that are easily overlooked; rapid acquisition and administration of antitoxin can prevent neuromuscular respiratory failure. In addition to Clostridium perfringens, IDU-related NSTIs can be caused by Clostridium sordellii and Clostridium novyi, which may share a distinct clinical presentation. Early definitive NSTI management, which decreases mortality, requires a low index of suspicion on the part of emergency physicians and low threshold for surgical exploration and debridement on the part of the surgeon. Tetanus should be preventable in the IDU population through careful attention to vaccination status.

Acute myonecrosis in horse caused by Clostridium novyi type A

The objective of this study was to describe the first report involving a case of equine acute myonecrosis caused by C. novyi type A with an emphasis on clinical signs, the pathological and bacteriological analysis, and molecular identification of the microorganisms as the key of the definitive diagnosis.

Mimicry epitope from Ehrlichia canis for interphotoreceptor retinoid-binding protein 201-216 prevents autoimmune uveoretinitis by acting as altered peptide ligand

We report here identification of novel mimicry epitopes for interphotoreceptor retinoid-binding protein (IRBP) 201-216, a candidate ocular antigen that causes experimental autoimmune uveoretinitis (EAU) in A/J mice. One mimicry epitope from Ehrlichia canis (EHC), designated EHC 44-59, induced cross-reactive T cells for IRBP 201-216 capable of producing T helper (Th)1 and Th17 cytokines, but failed to induce EAU in A/J mice. In addition, animals first primed with suboptimal doses of IRBP 201-216 and subsequently immunized with EHC 44-59 did not develop EAU; rather, the mimicry epitope prevented the disease induced by IRBP 201-216. However, alteration in the composition of EHC 44-59 by substituting alanine with valine at position 49, similar to the composition of IRBP 201-216, enabled the mimicry epitope to acquire uveitogenicity. The data provide new insights as to how microbes containing mimicry sequences for retinal antigens can prevent ocular inflammation by acting as naturally occurring altered peptide ligands.