Life-threatening clostridial infections

Formal Single Atom Editing of the Glycosylated Natural Product Fidaxomicin Improves Acid Stability and Retains Antibiotic Activity

Fidaxomicin (Fdx) constitutes a glycosylated natural product with excellent antibacterial activity against various Gram-positive bacteria but is approved only for Clostridioides difficile infections. Poor water solubility and acid lability preclude its use for other infections. Herein, we describe our strategy to overcome the acid lability by introducing acid-stable S-linked glycosides. We describe the direct, diastereoselective modification of unprotected Fdx without the need to avoid air or moisture. Using our newly established approach, Fdx was converted to the single atom exchanged analogue S-Fdx, in which the acid labile O-glycosidic bond to the noviose sugar was replaced by the acid stable S-glycosidic bond. Studies of the antibacterial activity of a structurally diverse set of thioglycoside derivatives revealed high potency of acyl derivatives of S-Fdx against Clostridioides difficile (MIC range: 0.12-4 μg/mL) and excellent potency against Clostridium perfringens (MIC range: 0.06-0.5 μg/mL).

Identification of a hemorrhagic determinant in Clostridioides difficile TcdA and Paeniclostridium sordellii TcsH

Paeniclostridium sordellii hemorrhagic toxin (TcsH) and Clostridioides difficile toxin A (TcdA) are two major members of the large clostridial toxin (LCT) family. These two toxins share ~87% similarity and are known to cause severe hemorrhagic pathology in animals. Yet, the pathogenesis of their hemorrhagic toxicity has been mysterious for decades. Here, we examined the liver injury after systemic exposure to different LCTs and found that only TcsH and TcdA induce overt hepatic hemorrhage. By investigating the chimeric and truncated toxins, we demonstrated that the enzymatic domain of TcsH alone is not sufficient to determine its potent hepatic hemorrhagic toxicity in mice. Likewise, the combined repetitive oligopeptide (CROP) domain of TcsH/TcdA alone also failed to explain their strong hemorrhagic activity in mice. Lastly, we showed that disrupting the first two short repeats of CROPs in TcsH and TcdA impaired hemorrhagic toxicity without causing overt changes in cytotoxicity and lethality. These findings lead to a deeper understanding of toxin-induced hemorrhage and the pathogenesis of LCTs and could be insightful in developing therapeutic avenues against clostridial infections.

IMPORTANCE

Paeniclostridium sordellii and Clostridioides difficile infections often cause hemorrhage in the affected tissues and organs, which is mainly attributed to their hemorrhagic toxins, TcsH and TcdA. In this study, we demonstrate that TcsH and TcdA, but not other related toxins. including Clostridioides difficile toxin B and TcsL, induce severe hepatic hemorrhage in mice. We further determine that a small region in TcsH and TcdA is critical for the hemorrhagic toxicity but not cytotoxicity or lethality of these toxins. Based on these results, we propose that the hemorrhagic toxicity of TcsH and TcdA is due to an uncharacterized mechanism, such as the presence of an unknown receptor, and future studies to identify the interactive host factors are warranted.

Paeniclostridium sordellii causing liver abscess: A rare case report in India

Paeniclostridium sordellii, an anaerobic bacterium, causes hepatic infections in alcoholics and post-surgery (liver transplantation). While liver and brain abscesses are rare, drainage procedures and targeted antibiotic therapy assisted by early microbiological diagnosis have reduced mortality rates. We report a rare case of pyogenic liver abscess caused by Paeniclostridium sordellii in India, the early diagnosis of which has led to life saving outcome for the patient. Hence, the microbiological diagnosis and comprehensive medical-surgical treatment are vital for preventing mortality in Paeniclostridium sordellii infections.

Overview of Bacterial Protein Toxins from Pathogenic Bacteria: Mode of Action and Insights into Evolution

Bacterial protein toxins are secreted by certain bacteria and are responsible for mild to severe diseases in humans and animals. They are among the most potent molecules known, which are active at very low concentrations. Bacterial protein toxins exhibit a wide diversity based on size, structure, and mode of action. Upon recognition of a cell surface receptor (protein, glycoprotein, and glycolipid), they are active either at the cell surface (signal transduction, membrane damage by pore formation, or hydrolysis of membrane compound(s)) or intracellularly. Various bacterial protein toxins have the ability to enter cells, most often using an endocytosis mechanism, and to deliver the effector domain into the cytosol, where it interacts with an intracellular target(s). According to the nature of the intracellular target(s) and type of modification, various cellular effects are induced (cell death, homeostasis modification, cytoskeleton alteration, blockade of exocytosis, etc.). The various modes of action of bacterial protein toxins are illustrated with representative examples. Insights in toxin evolution are discussed.

Repurposing rabeprazole sodium as an anti-Clostridium perfringens drug by inhibiting perfringolysin O

AIMS

Clostridium perfringens infections affect food safety, human health, and the development of the poultry feed industry. Anti-virulence is an alternative strategy to develop new drug. Perfringolysin O (PFO) is an exotoxin of C. perfringens that has been demonstrated to play critical roles in the pathogenesis of this organism, promising it an attractive target to explore drugs to combat C. perfringens infection.

METHODS AND RESULTS

Based on an activity-based screening, we identified six PFO inhibitors from the Food and Drug Administration (FDA)-approved drug library, among which rabeprazole sodium (RS) showed an optimal inhibitory effect with an IC50 of 1.82 ± 0.746 µg ml-1. The GLY57, ASP58, SER190, SER193-194, ASN199, GLU204, ASN377, THR379, and ALA200 in PFO interacted with RS during binding based on an energy analysis and H-bond analysis. This interaction blocked the oligomer formation of PFO, thereby inhibiting its cytotoxicity. RS treatment significantly increased the survival rate and alleviated pathological damage in C. perfringens or PFO-treated Galleria mellonella.

CONCLUSIONS

RS could potentially be used as a candidate drug for treating C. perfringens infection.

Unbridled Threat of Gas Gangrene in a Patient With Uncontrolled Diabetes Mellitus: A Compelling Case Report of Clostridium perfringens Infection

Clostridium perfringens, a Gram-positive anaerobic bacterium, is well-known for its association with gas gangrene, a severe and rapidly progressing infection characterized by tissue gas production and necrosis. In this case report, we present the instance of a 64-year-old male with poorly controlled diabetes mellitus who developed a C. perfringens-related infection following a traumatic foot wound. The report emphasizes the critical significance of early diagnosis and aggressive treatment in C. perfringens infections, particularly in patients with underlying risk factors. Detailed accounts of clinical findings, laboratory results, computed tomography, and surgical interventions are provided. A multidisciplinary approach proved essential for successful management. The inherent scholarly value of this case is substantiated by its meticulous documentation of the clinical trajectory, diagnostic modalities, and treatment modalities employed. The intricate collaboration across diverse medical disciplines, the uncommon manifestation of the infection following a traumatic foot wound, and the favorable outcome achieved through prompt and multidisciplinary intervention collectively contribute to the exceptional nature and didactic significance of this case. The dissemination of such clinical experiences assumes paramount importance in advancing medical scholarship, cultivating awareness, and engendering a profound comprehension of the complexities associated with C. perfringens infections, thereby enriching the wider scientific and medical community.

Autolysin as a fibronectin receptor on the cell surface of Clostridium perfringens

OBJECTIVE

Clostridium perfringens causes food poisoning and gas gangrene, a serious wound-associated infection. C. perfringens cells adhere to collagen via fibronectin (Fn). We investigated whether the peptidoglycan hydrolase of C. perfringens, i.e., autolysin (Acp), is implicated in Fn binding to C. perfringens cells.

METHODS

This study used recombinant Acp fragments, human Fn and knockout mutants (C. perfringens 13 acp::erm and HN13 ΔfbpC ΔfbpD). Ligand blotting, Western blotting analysis, and complementation tests were performed. The Fn-binding activity of each mutant was evaluated by ELISA.

RESULTS

From an Fn-binding assay using recombinant Acp fragments, Fn was found to bind to the catalytic domain of Acp. In mutant cells lacking Acp, Fn binding was significantly decreased, but was restored by the complementation of the acp gene. There are three known kinds of Fn-binding proteins in C. perfringens: FbpC, FbpD, and glyceraldehyde-3-phosphate dehydrogenase. We found no difference in Fn-binding activity between the mutant cells lacking both FbpC and FbpD (SAK3 cells) and the wild-type cells, indicating that these Fn-binding proteins are not involved in Fn binding to C. perfringens cells.

CONCLUSIONS

We found that the Acp is an Fn-binding protein that acts as an Fn receptor on the surface of C. perfringens cells.

Under the Skin: A Case Series of Clostridium sordellii Necrotizing Soft Tissue Infections in Patients Who Inject Drugs

Clostridium sordellii has been well-associated as a cause of obstetric infections but is a less commonly recognized organism of necrotizing skin and soft tissue infections (NSTI). C. sordelli infections are rare with only 14 cases reported in the literature to date. These infections are often associated with profound septic shock and the mortality rate remains high. We report four patients who presented with C. sordellii NSTI over a period of two years at an academic medical center. Notably, injection drug use was the main risk factor for infection in these patients. Appropriate management of C. sordellii NSTI necessitates a combination of antibiotics and emergent surgical intervention. However, despite these efforts, the mortality rate remains high, with three of the four patients dying. Clinicians should consider NSTI in the differential diagnosis when evaluating skin and soft tissue infections in people who inject drugs. Furthermore, it is imperative to educate patients who engage in injection drug use on the potential risks associated with NSTI and inform them of warning signs that warrant immediate medical attention. The devastating consequences of C. sordellii-associated NSTI in this vulnerable population can be mitigated by enhancing awareness and facilitating early intervention.

Probiotics and Human Milk Differentially Influence the Gut Microbiome and NEC Incidence in Preterm Pigs

Necrotizing enterocolitis (NEC) is the leading cause of death caused by gastrointestinal disease in preterm infants. Major risk factors include prematurity, formula feeding, and gut microbial colonization. Microbes have been linked to NEC, yet there is no evidence of causal species, and select probiotics have been shown to reduce NEC incidence in infants. In this study, we evaluated the effect of the probiotic Bifidobacterium longum subsp. infantis (BL. infantis), alone and in combination with a human milk oligosaccharide (HMO)-sialylactose (3'SL)-on the microbiome, and the incidence of NEC in preterm piglets fed an infant formula diet. We studied 50 preterm piglets randomized between 5 treatments: (1) Preterm infant formula, (2) Donor human milk (DHM), (3) Infant formula + 3'SL, (4) Infant formula + BL. infantis, and (5) Infant formula and BL. infantis + 3'SL. NEC incidence and severity were assessed through the evaluation of tissue from all the segments of the GI tract. The gut microbiota composition was assessed both daily and terminally through 16S and whole-genome sequencing (WGS) of rectal stool samples and intestinal contents. Dietary BL. infantis and 3'SL supplementation had no effect, yet DHM significantly reduced the incidence of NEC. The abundance of BL. infantis in the gut contents negatively correlated with disease severity. Clostridium sensu stricto 1 and Clostridium perfringens were significantly more abundant in NEC and positively correlated with disease severity. Our results suggest that pre- and probiotics are not sufficient for protection from NEC in an exclusively formula-based diet. The results highlight the differences in microbial species positively associated with both diet and NEC incidence.

Clostridium perfringens-Opportunistic Foodborne Pathogen, Its Diversity and Epidemiological Significance

The C. perfringens species is associated with various environments, such as soils, sewage, and food. However, it is also a component of the gastrointestinal (GI) microflora (i.e., microbiota) of sick and healthy humans and animals. C. perfringens is linked with different systemic and enteric diseases in livestock and humans, such as gas gangrene, food poisoning, non-foodborne diarrhoea, and enterocolitis. The strains of this opportunistic pathogen are known to secrete over 20 identified toxins that are considered its principal virulence factors. C. perfringens belongs to the anaerobic bacteria community but can also survive in the presence of oxygen. The short time between generations, the multi-production capability of toxins and heat-resistant spores, the location of many virulence genes on mobile genetic elements, and the inhabitance of this opportunistic pathogen in different ecological niches make C. perfringens a very important microorganism for public health protection. The epidemiological evidence for the association of these strains with C. perfringens-meditated food poisoning and some cases of non-foodborne diseases is very clear and well-documented. However, the genetic diversity and physiology of C. perfringens should still be studied in order to confirm the importance of suspected novel virulence traits. A very significant problem is the growing antibiotic resistance of C. perfringens strains. The aim of this review is to show the current basic information about the toxins, epidemiology, and genetic and molecular diversity of this opportunistic pathogen.

Comparison of sporulation and germination conditions for Clostridium perfringens type A and G strains

Clostridium perfringens is a spore forming, anaerobic, Gram-positive bacterium that causes a range of diseases in humans and animals. C. perfringens forms spores, structures that are derived from the vegetative cell under conditions of nutrient deprivation and that allows survival under harsh environmental conditions. To return to vegetative growth, C. perfringens spores must germinate when conditions are favorable. Previous work in analyzing C. perfringens spore germination has produced strain-specific results. Hence, we analyzed the requirements for spore formation and germination in seven different C. perfringens strains. Our data showed that C. perfringens sporulation conditions are strain-specific, but germination responses are homogenous in all strains tested. C. perfringens spores can germinate using two distinct pathways. The first germination pathway (the amino acid-only pathway or AA) requires L-alanine, L-phenylalanine, and sodium ions (Na⁺) as co-germinants. L-arginine is not a required germinant but potentiates germination. The AA pathway is inhibited by aromatic amino acids and potassium ions (K⁺). Bicarbonate (HCO₃^-), on the other hand, bypasses potassium-mediated inhibition of C. perfringens spore germination through the AA pathway. The second germination pathway (the bile salt / amino acid pathway or BA) is more promiscuous and is activated by several bile salts and amino acids. In contrast to the AA pathway, the BA pathway is insensitive to Na⁺, although it can be activated by either K⁺ or HCO₃^-. We hypothesize that some C. perfringens strains may have evolved these two distinct germination pathways to ensure spore response to different host environments.

Cervical Necrotizing Fasciitis, Diagnosis and Treatment of a Rare Life-Threatening Infection

IMPORTANCE

Necrotizing fasciitis is a relatively uncommon and potentially life-threatening soft tissue infection, with morbidity and mortality approaching 25% to 35%, even with optimal treatment. The challenge of diagnosis for necrotizing soft tissue infections (NSTIs) is their rarity, with the incidence of approximately 1000 cases annually in the United States. Given the rapid progression of disease and its similar presentation to more benign processes, early and definitive diagnosis is imperative.

FINDINGS

Signs and symptoms of NSTIs in the early stages are virtually indistinguishable from those seen with abscesses and cellulitis, making definitive diagnosis difficult. The clinical presentation will depend on the pathogen and its virulence factors which ultimately determine the area and depth of invasion into tissue. There are multiple laboratory value scoring systems that have been developed to support the diagnosis of an NSTI. The scoring system with the highest positive (92%) and negative (96%) predictive value is the laboratory risk indicator for necrotizing fasciitis (LRINEC). The score is determined by 6 serologic markers: C-reactive protein (CRP), total white blood cell (WBC) count, hemoglobin, sodium, creatinine, and glucose. A score ≥ 6 is a relatively specific indicator of necrotizing fasciitis (specificity 83.8%), but a score <6 is not sensitive (59.2%) enough to rule out necrotizing fasciitis. In terms of imaging, computed tomography (CT) imaging, while more sensitive (80%) than plain radiography in detecting abnormalities, is just as nonspecific. Computed tomography imaging of NSTIs demonstrates fascial thickening (with potential fat stranding), edema, subcutaneous gas, and abscess formation. Magnetic resonance imaging (MRI) has demonstrated sensitivity of 100% and specificity of 86%, though MRI may not show early cases of fascial involvement of necrotizing fasciitis.

CONCLUSIONS AND RELEVANCE

Necrotizing soft tissue infections are rapidly progressive and potentially fatal infections that require a high index of clinical suspicion to promptly diagnose and aggressive surgical debridement of affected tissue in order to ensure optimal outcomes.Prompt surgical and infectious disease consultation is necessary for the treatment and management of these patients. While imaging is useful for further characterization, it should not delay surgical consultation. Necrotizing soft tissue infection remains a clinical diagnosis, although plain radiography, CT imaging, and ultrasound can provide useful clues. In general, the management of these patients should include rapid diagnosis, using a combination of clinical suspicion, laboratory data (LRINEC score), and imaging (MRI being the recommended imaging modality), prompt infectious disease and surgical consultation, surgical debridement, and delayed reconstruction. Laboratory findings that can more strongly suggest a diagnosis of NSTI include elevated CRP, elevated WBC, low hemoglobin, decreased sodium, and increased creatinine. Imaging findings include fascial thickening (with potential fat stranding), edema, subcutaneous gas, and abscess formation. Broad-spectrum antibiotics should be started in all cases of suspected NSTI. Surgical debridement, however, remains the lynchpin for treatment of cervical necrotizing fasciitis.

Clostridium perfringens gas gangrene caused by closed abdominal injury: A case report and review of the literature

BACKGROUND

Abdominal Clostridium perfringens (C. perfringens) gas gangrene is a rare infection that has been described in the literature as most frequently occurring in postoperative patients with open trauma. Intra-abdominal gas gangrene caused by C. perfringens infection after closed abdominal injury is extremely rare, difficult to diagnose, and progresses rapidly with high mortality risk. Here, we report a case of C. perfringens infection caused by closed abdominal injury.

CASE SUMMARY

A 54-year-old male suffered multiple intestinal tears and necrosis after sustaining an injury caused by falling from a high height. These injuries and the subsequent necrosis resulted in intra-abdominal C. perfringens infection. In the first operation, we removed the necrotic intestinal segment, kept the abdomen open and covered the intestine with a Bogota bag. A vacuum sealing drainage system was used to cover the outer layer of the Bogota bag, and the drainage was flushed under negative pressure. The patient was transferred to the intensive care unit for supportive care and empirical antibiotic treatment. The antibiotics were not changed until the results of bacterial culture and drug susceptibility testing were obtained. Two consecutive operations were then performed due to secondary intestinal necrosis. After three definitive operations, the patient successfully survived the perioperative period. Unfortunately, he died of complications related to Guillain-Barre syndrome 75 d after the first surgery. This paper presents this case of intra-abdominal gas gangrene infection and analyzes the diagnosis and treatment based on a review of current literature.

CONCLUSION

When the intestines rupture leading to contamination of the abdominal cavity by intestinal contents, C. perfringens bacteria normally present in the intestinal tract may proliferate in large numbers and lead to intra-abdominal infection. Prompt surgical intervention, adequate drainage, appropriate antibiotic therapy, and intensive supportive care comprise the most effective treatment strategy. If the abdominal cavity is heavily contaminated, an open abdominal approach may be a beneficial treatment.

Infections caused by Clostridium perfringens and Paeniclostridium sordellii after unsafe abortion

After the legalisation of abortion in the USA in 1973, the risk of infectious morbidity and mortality from this procedure notably decreased. With increasingly restrictive legislation targeting access to safe abortion services, reviewing infectious complications of unsafe pregnancy termination is crucial, particularly the diagnosis and management of life-threatening clostridial (and related anaerobic bacterial) infections that can complicate unsafe abortion. This Review deals with two especially devastating infections that are well-documented causes of septic abortion: the anaerobic, spore-forming pathogens Clostridium perfringens and Paeniclostridium sordellii. We seek to familiarise the reader with these bacteria, the clinical syndromes they can cause (with a focus on toxic shock syndrome), and provide a review of diagnosis and treatment options.

Targeting the Impossible: A Review of New Strategies against Endospores

Endospore-forming bacteria are ubiquitous, and their endospores can be present in food, in domestic animals, and on contaminated surfaces. Many spore-forming bacteria have been used in biotechnological applications, while others are human pathogens responsible for a wide range of critical clinical infections. Due to their resistant properties, it is challenging to eliminate spores and avoid the reactivation of latent spores that may lead to active infections. Furthermore, endospores play an essential role in the survival, transmission, and pathogenesis of some harmful strains that put human and animal health at risk. Thus, different methods have been applied for their eradication. Nevertheless, natural products are still a significant source for discovering and developing new antibiotics. Moreover, targeting the spore for clinical pathogens such as Clostridioides difficile is essential to disease prevention and therapeutics. These strategies could directly aim at the structural components of the spore or their germination process. This work summarizes the current advances in upcoming strategies and the development of natural products against endospores. This review also intends to highlight future perspectives in research and applications.

Surgical Emergencies in the ICU

Surgical emergencies are common in the critical care setting and require prompt diagnosis and management. Here, we discuss some of the surgical emergencies involving the gastrointestinal, hepatobiliary, and genitourinary sites. In addition, foreign body aspiration and necrotizing soft-tissue infections have been elaborated. Clinicians should be aware of the risk factors, keys examination findings, diagnostic modalities, and medical as well as surgical treatment options for these potentially fatal illnesses.

Short Chain Fatty Acid Metabolism in Relation to Gut Microbiota and Genetic Variability

It is widely accepted that the gut microbiota plays a significant role in modulating inflammatory and immune responses of their host. In recent years, the host-microbiota interface has gained relevance in understanding the development of many non-communicable chronic conditions, including cardiovascular disease, cancer, autoimmunity and neurodegeneration. Importantly, dietary fibre (DF) and associated compounds digested by the microbiota and their resulting metabolites, especially short-chain fatty acids (SCFA), were significantly associated with health beneficial effects, such as via proposed anti-inflammatory mechanisms. However, SCFA metabolic pathways are not fully understood. Major steps include production of SCFA by microbiota, uptake in the colonic epithelium, first-pass effects at the liver, followed by biodistribution and metabolism at the host's cellular level. As dietary patterns do not affect all individuals equally, the host genetic makeup may play a role in the metabolic fate of these metabolites, in addition to other factors that might influence the microbiota, such as age, birth through caesarean, medication intake, alcohol and tobacco consumption, pathogen exposure and physical activity. In this article, we review the metabolic pathways of DF, from intake to the intracellular metabolism of fibre-derived products, and identify possible sources of inter-individual variability related to genetic variation. Such variability may be indicative of the phenotypic flexibility in response to diet, and may be predictive of long-term adaptations to dietary factors, including maladaptation and tissue damage, which may develop into disease in individuals with specific predispositions, thus allowing for a better prediction of potential health effects following personalized intervention with DF.

Piceatannol Alleviates Clostridium perfringens Virulence by Inhibiting Perfringolysin O

Clostridium perfringens (C. perfringens) is an important foodborne pathogen that can cause diseases such as gas gangrene and necrotizing enteritis in a variety of economic animals, seriously affecting public health and the economic benefits and healthy development of the livestock and poultry breeding industry. Perfringolysin O (PFO) is an important virulence factor of C. perfringens and plays critical roles in necrotic enteritis and gas gangrene, rendering it an ideal target for developing new drugs against infections caused by this pathogen. In this study, based on biological activity inhibition assays, oligomerization tests and computational biology assays, we found that the foodborne natural component piceatannol reduced pore-forming activity with an inhibitory ratio of 83.84% in the concentration of 16 µg/mL (IC₅₀ = 7.83 µg/mL) by binding with PFO directly and changing some of its secondary structures, including 3-Helix, A-helix, bend, and in turn, ultimately affecting oligomer formation. Furthermore, we confirmed that piceatannol protected human intestinal epithelial cells from the damage induced by PFO with LDH release reduced by 38.44% at 16 µg/mL, based on a cytotoxicity test. By performing an animal experiment, we found the C. perfringens clones showed an approximate 10-fold reduction in infected mice. These results suggest that piceatannol may be a candidate for anti-C. perfringens drug development.

Development of multiplex PCR panel for detection of anaerobic bacteria in clinical samples

OBJECTIVE

Although anaerobic bacteria are important agents of a wide variety of serious infections, they are overlooked often in the etiology of infection due to difficulties in isolation and detection. The aim of this study was to develop a new multiplex PCR panel that could detect Bacteroides, Fusobacterium, Prevotella, Veillonella, Clostridium, Peptostreptococcus, and Actinomyces bacteria, which are the most frequently isolated from anaerobic infections, at the genus level.

METHOD

Aerobic and anaerobic cultures were performed on 46 clinical specimens, with suspicion of anaerobic infection and were sent to the laboratory. DNA isolation was performed with the same samples and anaerobic bacteria were detected by the multiplex PCR test developed in the study.

RESULT

The analytical sensitivity of the multiplex PCR assay was found to be 1-10³ CFU/ml, depending on the bacterial species. In this study, anaerobic growth was observed in eight (17.4%) of 46 clinical samples. The multiplex PCR test detected 35 anaerobic bacteria from 20 (43.5%) of 46 clinical samples. The most common anaerobes isolated from clinical specimens by the multiplex PCR assay were Prevotella spp. (37.1%) and Fusobacterium spp. (22.9%) while Clostridium spp. (14.3%), Peptostreptococcus spp. (11.4%), Bacteroides spp. (8.6%), and Veillonella spp. (5.7%) followed these genera.

CONCLUSION

As a result, it was concluded that the multiplex PCR panel developed in this study eliminates problems in the detection of anaerobes based on culture, provides more accurate detection of anaerobic bacteria from clinical specimens, takes a shorter time, and allows more accurate infection treatment.

Clostridium septicum α-toxin activates the NLRP3 inflammasome by engaging GPI-anchored proteins

Clostridium species are a group of Gram-positive bacteria that cause diseases in humans, such as food poisoning, botulism, and tetanus. Here, we analyzed 10 different Clostridium species and identified that Clostridium septicum, a pathogen that causes sepsis and gas gangrene, activates the mammalian cytosolic inflammasome complex in mice and humans. Mechanistically, we demonstrate that α-toxin secreted by C. septicum binds to glycosylphosphatidylinositol (GPI)-anchored proteins on the host plasma membrane, oligomerizing and forming a membrane pore that is permissive to efflux of magnesium and potassium ions. Efflux of these cytosolic ions triggers the activation of the innate immune sensor NLRP3, inducing activation of caspase-1 and gasdermin D, secretion of the proinflammatory cytokines interleukin-1β and interleukin-18, pyroptosis, and plasma membrane rupture via ninjurin-1. Furthermore, α-toxin of C. septicum induces rapid inflammasome-mediated lethality in mice and pharmacological inhibition of the NLRP3 inflammasome using MCC950 prevents C. septicum-induced lethality. Overall, our results reveal that cytosolic innate sensing of α-toxin is central to the recognition of C. septicum infection and that therapeutic blockade of the inflammasome pathway may prevent sepsis and death caused by toxin-producing pathogens.

First Comparative Analysis of Clostridium septicum Genomes Provides Insights Into the Taxonomy, Species Genetic Diversity, and Virulence Related to Gas Gangrene

Clostridium septicum is a Gram-positive, toxin-producing, and spore-forming bacterium that is recognized, together with C. perfringens, as the most important etiologic agent of progressive gas gangrene. Clostridium septicum infections are almost always fatal in humans and animals. Despite its clinical and agricultural relevance, there is currently limited knowledge of the diversity and genome structure of C. septicum. This study presents the complete genome sequence of C. septicum DSM 7534T type strain as well as the first comparative analysis of five C. septicum genomes. The taxonomy of C. septicum, as revealed by 16S rRNA analysis as well as by genomic wide indices such as protein-based phylogeny, average nucleotide identity, and digital DNA–DNA hybridization indicates a stable clade. The composition and presence of prophages, CRISPR elements and accessory genetic material was variable in the investigated genomes. This is in contrast to the limited genetic variability described for the phylogenetically and phenotypically related species Clostridium chauvoei. The restriction-modification (RM) systems between two C. septicum genomes were heterogeneous for the RM types they encoded. C. septicum has an open pangenome with 2,311 genes representing the core genes and 1,429 accessory genes. The core genome SNP divergence between genome pairs varied up to 4,886 pairwise SNPs. A vast arsenal of potential virulence genes was detected in the genomes studied. Sequence analysis of these genes revealed that sialidase, hemolysin, and collagenase genes are conserved compared to the α-toxin and hyaluronidase genes. In addition, a conserved gene found in all C. septicum genomes was predicted to encode a leucocidin homolog (beta-channel forming cytolysin) similar (71.10% protein identity) to Clostridium chauvoei toxin A (CctA), which is a potent toxin. In conclusion, our results provide first, valuable insights into strain relatedness and genomic plasticity of C. septicum and contribute to our understanding of the virulence mechanisms of this important human and animal pathogen.

Navarro M, Li J, Shrestha A, Uzal F, A. McClane B. Pathogenicity and virulence of Clostridium perfringens

Clostridium perfringens is an extremely versatile pathogen of humans and livestock, causing wound infections like gas gangrene (clostridial myonecrosis), enteritis/enterocolitis (including one of the most common human food-borne illnesses), and enterotoxemia (where toxins produced in the intestine are absorbed and damage distant organs such as the brain). The virulence of this Gram-positive, spore-forming, anaerobe is largely attributable to its copious toxin production; the diverse actions and roles in infection of these toxins are now becoming established. Most C. perfringens toxin genes are encoded on conjugative plasmids, including the pCW3-like and the recently discovered pCP13-like plasmid families. Production of C. perfringens toxins is highly regulated via processes involving two-component regulatory systems, quorum sensing and/or sporulation-related alternative sigma factors. Non-toxin factors, such as degradative enzymes like sialidases, are also now being implicated in the pathogenicity of this bacterium. These factors can promote toxin action in vitro and, perhaps in vivo, and also enhance C. perfringens intestinal colonization, e.g. NanI sialidase increases C. perfringens adherence to intestinal tissue and generates nutrients for its growth, at least in vitro. The possible virulence contributions of many other factors, such as adhesins, the capsule and biofilms, largely await future study.

Clinical anaerobic infections in an Indian tertiary care hospital: A two-year retrospective study

OBJECTIVE

To study the spectrum of anaerobic infections and the frequency of clinically relevant anaerobes in various infections in a tertiary care hospital in North India.

METHOD

In this two-year (2018-2019) retrospective study, a total of 22,177 samples were processed both anaerobically and aerobically. The samples included blood, pus, body fluids, necrotic tissues, abscess, peritoneal fluids, and other specimens of conditions predisposing to anaerobic infections. The recovered bacterial isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

RESULT

Of the 22,177 samples processed anaerobically, 1094 showed significant anaerobic growth yielding 1464 anaerobes. Bacteroides fragilis (12.7%) and Peptoniphilus harei (12.2%) were the most predominant anaerobes, whereas Escherichia coli (32.6%) and Staphylococcus aureus (13.2%) were the most frequently recovered facultative anaerobes in polymicrobial growth. Both aerobic and anaerobic data were available for 673/1094 samples, of which 68% represented a polymicrobial etiology and 32% as monomicrobial. Of the cases where complete clinical information was available (504/1094), the majority of the anaerobes were recovered from the skin and soft tissue infections (36.3%) and intra-abdominal infections (17.1%). The clinical specimen most frequently growing anaerobes was abscess (29.1%), followed by diabetic foot ulcers (14.1%).

CONCLUSION

The study documents the frequency of clinically significant anaerobic bacteria in various infections, and their associations with aerobes in polymicrobial growth. The present study may aid us in devising better therapeutic strategies against both aerobes and anaerobes in anaerobic infections, which is often empirical. Besides, the data can update clinicians with the changing patterns of anaerobic infections, which remains a neglected concern.

Bacterial phospholipases C with dual activity: phosphatidylcholinesterase and sphingomyelinase

Bacterial phospholipases and sphingomyelinases are lipolytic esterases that are structurally and evolutionarily heterogeneous. These enzymes play crucial roles as virulence factors in several human and animal infectious diseases. Some bacterial phospholipases C (PLCs) have both phosphatidylcholinesterase and sphingomyelinase C activities. Among them, Listeria  monocytogenes PlcB, Clostridium perfringens PLC, and Pseudomonas aeruginosa PlcH are the most deeply understood. In silico predictions of substrates docking with these three bacterial enzymes provide evidence that they interact with different substrates at the same active site. This review discusses structural aspects, substrate specificity, and the mechanism of action of those bacterial enzymes on target cells and animal infection models to shed light on their roles in pathogenesis.

Non-C. difficile Clostridioides Bacteremia in Intensive Care Patients, France

Article Summary: This multicenter study focusing on critically ill patients showed a strong relationship between hemolysis and mortality.

Usually responsible for soft tissue infections, Clostridioides species can also cause bacteremia, life-threatening infections often requiring intensive care unit (ICU) admission. We conducted a multicenter retrospective study to investigate Clostridioides bacteremia in ICUs to describe the clinical and biologic characteristics and outcomes in critically ill patients. We identified 135 patients with Clostridioides bacteremia, which occurred almost exclusively (96%) in patients with underlying conditions. Septic shock and digestive symptoms were the hallmarks of Clostridioides bacteremia in the ICU. We identified 16 different species of Clostridioides, among which C. perfringens accounted for 31% of cases. Despite the high sensitivity of Clostridioides to common antimicrobial drugs, mortality rates were high: 52% for ICU patients and 71% overall at 3 months. In multivariate analysis, the most important factor associated with increased risk for death was the presence of hemolysis. Clostridioides bacteremia often leads to multiple organ failures, which have high mortality rates.

Concurrent Clostridium septicum bacteremia and colorectal adenocarcinoma with metastasis to the brain - A Case Report

There is a known relationship between Clostridium septicum bacteremia and colorectal malignancies. C. septicum is a gram-positive, anaerobic, spore-forming bacterium that can survive the acidic colorectal tumor microenvironment, where it is thought to enter the blood by tumor-mediated epithelial tissue damage. While in circulation, C. septicum can release exotoxins which may lead to life-threatening sepsis. The patient in this case presented with a mild fever, abdominal pain, and left hand weakness. Imaging of the head and abdomen revealed a right frontal lucency and wall thickening of the ascending colon. Two colonic adenocarcinomas were found and removed via an exploratory laparotomy and right hemicolectomy. The blood culture was positive for C. septicum. Brain MRI confirmed a right frontal mass concerning for metastasis. Here, we discuss the relationship between colonic cancers and Clostridium septicum bacteremia.

Clostridium perfringens bloodstream infection secondary to acute pancreatitis: A case report

BACKGROUND

Clostridium perfringens (C. perfringens) is an opportunistic pathogen. It can cause infections after birth, after an abortion, and in patients with diabetes, malignancy, liver cirrhosis, or an immunosuppressive state. Here, we report a patient with C. perfringens infection secondary to acute pancreatitis, with no underlying diabetes, malignancy, or liver cirrhosis.

CASE SUMMARY

A 62-year-old Han Chinese woman presented to the Tianjin Hospital of ITCWM Nankai Hospital on January 8, 2020 because of epigastric abdominal pain. Laboratory examination showed that urine amylase was 10403 U/L (reference: 47-458), and blood amylase was 1006 U/L (reference: < 100). Abdominal computed tomography showed pancreatic edema and peripancreatic exudation. She was diagnosed with mild acute pancreatitis and treated accordingly. She was readmitted the next day for similar symptoms. Two hours later, she went to the lavatory and urinated, and the urine color was like soy sauce. Oxygen saturation decreased to 77%, and she developed consciousness disturbance. She was admitted to the intensive care unit. After 8 h in the hospital, she had a high fever of 40 ℃, blood was drawn for culture, and 3 g of cefoperazone/sulbactam was administered. After 12 h, she had a cardiac arrest and died shortly. Blood culture confirmed a C. perfringens infection.

CONCLUSION

C. perfringens infection may be secondary to acute pancreatitis. Rapid recognition and aggressive early management are critical for the survival of patients with C. perfringens infection.

Rapidly progressive and fatal distant spontaneous gas gangrene due to Clostridium septicum after biopsy of malignant cecal mass

Clostridium species are known to cause myonecrosis and gas gangrene which are often fatal infections in the setting of trauma but also spontaneously in certain populations such as colorectal malignancy, immunosuppression, and neutropenia. We report a case of an 83-year-old male who developed fatal and rapidly progressive gas gangrene due to Clostridium septicum within 48 h after biopsy of suspected malignant cecal mass. To our knowledge, such a drastic, rapid and fatal presentation after a diagnostic biopsy of malignant mass has not been previously reported and is something to be watchful for in suspected colon cancer cases.

Probiotics in the dairy industry-Advances and opportunities

The past two decades have witnessed a global surge in the application of probiotics as functional ingredients in food, animal feed, and pharmaceutical products. Among food industries, the dairy industry is the largest sector where probiotics are employed in a number of dairy products including sour/fermented milk, yogurt, cheese, butter/cream, ice cream, and infant formula. These probiotics are either used as starter culture alone or in combination with traditional starters, or incorporated into dairy products following fermentation, where their presence imparts many functional characteristics to the product (for instance, improved aroma, taste, and textural characteristics), in addition to conferring many health-promoting properties. However, there are still many challenges related to the stability and functionality of probiotics in dairy products. This review highlights the advances, opportunities, and challenges of application of probiotics in dairy industries. Benefits imparted by probiotics to dairy products including their role in physicochemical characteristics and nutritional properties (clinical and functional perspective) are also discussed. We transcend the traditional concept of the application of probiotics in dairy products and discuss paraprobiotics and postbiotics as a newly emerged concept in the field of probiotics in a particular relation to the dairy industry. Some potential applications of paraprobiotics and postbiotics in dairy products as functional ingredients for the development of functional dairy products with health-promoting properties are briefly elucidated.

Vaccination against pathogenic clostridia in animals: a review

Clostridium is a Gram-positive, rod-shaped, anaerobic, and spore-forming bacterium, which is found in the surrounding environments throughout the world. Clostridium species cause botulism, tetanus, enterotoxaemia, gas gangrene, necrotic enteritis, pseudomembranous colitis, blackleg, and black disease. Clostridium infection causes severe economic losses in livestock and poultry industries. Vaccination seems to be an effective way to control Clostridial diseases. This review discusses the toxins and vaccine development of the most common pathogenic Clostridium species in animals, including Clostridium perfringens, Clostridium novyi, Clostridium chauvoei, and Clostridium septicum. In this comprehensive study, we will review different kinds of clostridial toxins and the vaccines that are experimentally or practically available and will give a short description on each vaccine focusing on its applications, advantages, and disadvantages.

Rapidly fatal necrotizing soft tissue infection due to Clostridium sordellii in an injection drug user

Clostridium sordellii infections are known to be associated with high morbidity and mortality. To date, only a small number of cases with necrotizing soft tissue infection due to C. Sordellii have been reported. We report a case presented with necrotizing soft tissue infection of the right upper extremity caused by C. sordellii in a patient with known use of injected heroin. Despite broad spectrum antibiotics and surgical debridement, the patient's clinical course became rapidly fatal, within 24 h of admission. C. sordellii necrotizing soft tissue infections are particularly virulent. Even in the context of appropriate surgical debridement, these infections can be rapidly fatal. This case highlights the importance of high suspicion for C. sordellii as potential pathogen of necrotizing soft tissue infection in injection drug users.

Prevalence, Genotypic and Phenotypic Characterization and Antibiotic Resistance Profile of Clostridium perfringens Type A and D Isolated from Feces of Sheep (Ovis aries) and Goats (Capra hircus) in Punjab, Pakistan

Clostridium perfringens poses a serious threat to small ruminants by causing moderate to severe enterotoxaemia. Due to its ability to produce a wide arsenal of toxins, it is ranked among the most prevalent and important pathogens in livestock. This study focused on the molecular characterization of different Clostridium perfringens types along with their antimicrobial resistance profile. An overall higher prevalence of C. perfringens (46.1%) was detected based on mPCR among sheep and goats (healthy and diseased) in the Punjab province, Pakistan. The majority of the isolates were characterized as type A (82%), followed by type D (18%). Among the isolates from diseased sheep and goats, 27% were positive for cpa, 49% for cpa and cpb2, 9% for cpa and etx, 15% for cpa, cpb2 and etx. In the case of isolates from healthy sheep and goats, 59% were positive for cpa, 34% for cpb2 and cpa, 4% for cpa and etx, and 3% for cpa, cpb2 and etx. The prevalence of the beta2 toxin gene in the diseased sheep and goat population was 64% as compared to 37% in healthy animals. All 184 isolates (100%) were sensitive to rifampin and ceftiofur; the majority (57%) was sensitive to teicoplanin, chloramphenicol, amoxicillin, linezolid and enrofloxacin. A lower proportion of isolates (43%) were sensitive to ciprofloxacin and only 14% were susceptible to erythromycin. The findings of this study highlight the higher prevalence of C. perfringens in small ruminants and indicate that detailed pathogenesis studies are necessary to understand the explicit role of various toxins in causing enteric infections in sheep and goats including how they might be exploited to develop vaccines against these diseases.

Clostridial Gas Gangrene - A Rare but Deadly Infection: Case series and Comparison to Other Necrotizing Soft Tissue Infections

Objective

Clostridial gas gangrene (GG) or clostridial myonecrosis is a very rare but life‐threatening necrotizing soft tissue infection (NSTI) caused by anaerobic, spore‐forming, and gas‐producing clostridium subspecies. It is the most rapidly spreading and lethal infection in humans, also affecting muscle tissue. The high mortality, of up to 100%, in clostridial GG is mediated by potent bacterial exotoxins. Necrotizing fasciitis (NF) is an important differential diagnosis, most often caused by group A streptococci, primarily not affecting musculature but the subcutaneous tissue and fascia. In the early stages of the infection, it is difficult to distinguish between GG and NF. Therefore, we compare both infection types, identify relevant differences in initial clinical presentation and later course, and present the results of our patients in a retrospective review.

Methods

Patients diagnosed with GG from 2008 to 2018 in our level one trauma center were identified. Their charts were reviewed retrospectively and data analyzed in terms of demographic information, microbiological and histological results, therapeutic course, outcome, and mortality rates. The laboratory risk indicator for NF (LRINEC) score was applied on the first blood work acquired. Results were compared to those of a second group diagnosed with NF.

Results

Five patients with GG and nine patients with NF were included in the present study. Patients with GG had a mortality rate of 80% compared to 0% in patients with NF. In eight patients with NF, affected limbs could be salvaged; one NF underwent amputation. LRINEC did not show significant differences between the groups; however, C‐reactive protein was significantly increased (P = 0.009) and hemoglobin (Hb) was significantly decreased (P = 0.02) in patients with GG. Interleukin‐6 and procalcitonin levels did not show significant difference. Patients with GG were older (70.2 vs 50 years). Of the isolated bacteria, 86% were sensitive to the initial calculated antibiotic treatment with ampicillin‐sulbactam or imipenem plus metronidazole plus clindamycin.

Conclusion

Both GG and NF need full‐scale surgical, antibiotic, and intensive care treatment, especially within the first days. Among patients with NSTI, those with clostridial GG have a significantly increased mortality risk due to early septic shock caused by clostridial toxins. In the initial stages, clinical differences are hardly detectable. Immediate surgical debridement is the key to successful therapy for NSTI and needs to be performed as early as possible. However, patients should be treated in a center with an experienced interdisciplinary intensive care team based on a predetermined treatment plan.

Sudden death caused by Clostridium perfringens sepsis presenting as massive intravascular hemolysis

An 80-year-old Japanese woman with diabetes mellitus was admitted with gastrointestinal symptoms and pyrexia. At presentation, liver abscesses and severe hemolytic anemia were noted. Before detailed diagnostic evaluation and adequate treatment, she suddenly died 2.5 hours after admission. The autopsy and bacteriological examinations revealed liver abscesses and massive intravascular hemolysis caused by Clostridium perfringens as well as other miscellaneous critical pathological findings, including acute renal tubular necrosis, lung edema, and pulmonary fat embolism. In this article, the detailed autopsy results are described and clinicopathologic characteristics on Clostridium perfringens-related sudden death are discussed with a review of the literature.

Relevance of anaerobic bacteremia in adult patients: A never-ending story?

Obligate anaerobic bacteria are considered important constituents of the microbiota of humans; in addition, they are also important etiological agents in some focal or invasive infections and bacteremia with a high level of mortality. Conflicting data have accumulated over the last decades regarding the extent in which these pathogens play an intrinsic role in bloodstream infections. Clinical characteristics of anaerobic bloodstream infections do not differ from bacteremia caused by other pathogens, but due to their longer generation time and rigorous growth requirements, it usually takes longer to establish the etiological diagnosis. The introduction of matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) has represented a technological revolution in microbiological diagnostics, which has allowed for the fast, accurate and reliable identification of anaerobic bacteria at a low sample cost. The purpose of this review article is to summarize the currently available literature data on the prevalence of anaerobic bacteremia in adults for physicians and clinical microbiologists and to shed some light on the complexity of this topic nowadays.

A case report of iatrogenic gas gangrene post colonoscopy successfully treated with conservative management- is surgery always necessary?

Background

Colonoscopy is a routine procedure in diagnosis and treatment of colonic disease. While generally regarded as a safe procedure, potentially fatal complications can occur. Gas gangrene is one such complication, with very high mortality. There are few cases of gas gangrene occurring after colonoscopy, making it one of the rarer complications of this procedure. There have been no previously reported cases of a patient surviving such an infection and the optimal treatment strategy is contentious. This report describes a case of intramural gas gangrene of the colon, treated conservatively with antibiotic therapy in which the patient survived with full recovery.

Case presentation

A 71-year-old, previously healthy male presented 6 h post apparently uncomplicated colonoscopic polypectomy with rigors, nausea, vomiting and right upper quadrant pain. At presentation he was febrile at 40.1 °C but hemodynamically stable. Abdominal computed tomography revealed substantial colonic thickening and several focal intramural gas bubbles (pneumatosis intestinalis) surrounding the polypectomy site. Within 24 h post procedure he became hypotensive and was admitted to ICU in frank septic shock requiring inotropes, and with demonstrable septic myocardial depression. Bloods showed multi-organ derangement with leukocytosis, lactic acidosis, haemolytic anaemia and hyperbilirubinemia. A diagnosis of presumed Clostridial gas gangrene was made, and treatment was initiated with benzylpenicillin, clindamycin, metronidazole and vancomycin. After 4 days in ICU he was stepped down, and discharged after a further 10 days with no surgical or endoscopic interventions. At three-month review he reported being back to full health.

Conclusions

This case demonstrates that gas gangrene infection is a possible complication of colonoscopic polypectomy. This is a cause of rapid deterioration in post-colonoscopy patients and has been misdiagnosed as colonic perforation in previously reported cases of retroperitoneal gas gangrene. Such misdiagnosis delays antibiotic therapy, which likely plays a role in the high mortality of this condition. Early diagnosis and initiation of antibiotic therapy with benzylpenicillin and clindamycin as seen in this case is essential for patient survival. While surgery is typically performed, non-operative management of pneumatosis intestinalis, and potentially gas gangrene is becoming more common and was utilized effectively in this patient.

Distant myonecrosis by atraumatic Clostridium septicum infection in a patient with metastatic breast cancer

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Atraumatic Clostridium septicum infection is seen in metastatic breast cancer.

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Rapid identification and aggressive treatment atypical of clostridial species is required.

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Atraumatic infection may require debridement beyond visible necrosis.

Clostridium septicum is an anaerobic, gram-positive bacillus known to cause myonecrosis, also known as gas gangrene, a life-threatening necrotizing soft tissue infection. Though it accounts for just 1 % of all infections attributable to Clostridia spp., C. septicum is a highly virulent and aggressive pathogen. Classic presentations of infection include bacteremia resulting in shock, myonecrosis, and vascular seeding. C. septicum-associated gas gangrene most commonly occurs in the setting of traumatic injury, but has also been reported in patients with colorectal malignancy, immunosuppression, neutropenia, and exceedingly rare in association with breast cancer. We report the case of a 56-year-old female patient with stage IV mixed lobar and ductal breast carcinoma with metastasis to the bone and liver, who presented with spontaneous C. septicum myonecrosis of the right hand. No prior traumatic injury was noted. Following amputation of the right forearm, antibiotic treatment, and multiorgan support, the patient passed following transition to palliative care. We hope to increase awareness of this relatively uncommon, though potentially deadly pathogen, as well as to discuss treatment options in patients infected with C. septicum.

Clinical Performance of the Novel GenMark Dx ePlex Blood Culture ID Gram-Positive Panel

Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel.

Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel. Ten microbiology laboratories throughout the United States collected residual, deidentified positive blood culture samples for analysis. Five laboratories tested both clinical and contrived samples with the BCID-GP Panel. Comparator identification methods included each laboratory’s SOC, which included matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and automated identification systems as well as targeted PCR/analytically validated real-time PCR (qPCR) with bidirectional sequencing. A total of 2,342 evaluable samples (1,777 clinical and 565 contrived) were tested with the BCID-GP Panel. The overall sample accuracy for on-panel organisms was 89% before resolution of discordant results. For pathogenic Gram-positive targets (Bacillus cereus group, Enterococcus spp., Enterococcus faecalis, Enterococcus faecium, Staphylococcus spp., Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Listeria spp., Listeria monocytogenes, Streptococcus spp., Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae, and Streptococcus pyogenes), positive percent agreement (PPA) and negative percent agreement (NPA) ranged from 93.1% to 100% and 98.8% to 100%, respectively. For contamination rule-out targets (Bacillus subtilis group, Corynebacterium, Cutibacterium acnes, Lactobacillus, and Micrococcus), PPA and NPA ranged from 84.5% to 100% and 99.9% to 100%, respectively. Positive percent agreement and NPA for the Pan Candida and Pan Gram-Negative targets were 92.4% and 95.7% for the former and 99.9% and 99.6% for the latter. The PPAs for resistance markers were as follows: mecA, 97.2%; mecC, 100%; vanA, 96.8%; and vanB, 100%. Negative percent agreement ranged from 96.6% to 100%. In conclusion, the ePlex BCID-GP Panel compares favorably to SOC and targeted molecular methods for the identification of 20 Gram-positive pathogens and four antimicrobial resistance genes in positive blood culture bottles. This panel detects a broad range of pathogens and mixed infections with yeast and Gram-negative organisms from the same positive blood culture bottle.

Amentoflavone Attenuates Clostridium perfringens Gas Gangrene by Targeting Alpha-Toxin and Perfringolysin O

Clostridium perfringens (C. perfringens) type A strains are the main cause of gas gangrene in humans and animals. Treatment of this lethal disease is limited, and the prognosis is not good. Alpha-toxin (CPA) and perfringolysin O (PFO) secreted by C. perfringens play irreplaceable roles in cytotoxicity to host cells, persistence in host tissues, and lethality of gas gangrene pathology. This work determined the influence of amentoflavone, a biflavonoid isolated from Selaginella tamariscina and other plants, on hemolysis and cytotoxicity mediated by CPA and PFO and evaluated the in vivo therapeutic effect on gas gangrene. Our data showed that amentoflavone could block the hemolysis and cytotoxicity induced by CPA and PFO in vitro, thereby mediating significant protection against mortality of infected mice in a mouse gas gangrene model, efficient bacterial clearance in tissues and alleviation of histological damage in vivo. Based on the above results, amentoflavone may be a potential candidate against C. perfringens infection by reducing CPA and PFO-mediated virulence.

Genomics of the Pathogenic Clostridia

Whole-genome sequences are now available for all the clinically important clostridia and many of the lesser or opportunistically pathogenic clostridia. The complex clade structures of C. difficile, C. perfringens, and the species that produce botulinum toxins have been delineated by whole-genome sequence analysis. The true clostridia of cluster I show relatively low levels of gross genomic rearrangements within species, in contrast to the species of cluster XI, notably C. difficile, which have been found to have very plastic genomes with significant levels of chromosomal rearrangement. Throughout the clostridial phylotypes, a large proportion of the strain diversity is driven by the acquisition and loss of mobile elements, including phages, plasmids, insertion sequences, and transposons. Genomic analysis has been used to investigate the diversity and spread of C. difficile within hospital settings, the zoonotic transfer of isolates, and the emergence, origins, and geographic spread of epidemic ribotypes. In C. perfringens the clades defined by chromosomal sequence analysis show no indications of clustering based on host species or geographical location. Whole-genome sequence analysis helps to define the different survival and pathogenesis strategies that the clostridia use. Some, such as C. botulinum, produce toxins which rapidly act to kill the host, whereas others, such as C. perfringens and C. difficile, produce less lethal toxins which can damage tissue but do not rapidly kill the host. The genomes provide a resource that can be mined to identify potential vaccine antigens and targets for other forms of therapeutic intervention.

Dynamics of toxigenic Clostridium perfringens colonisation in a cohort of prematurely born neonatal infants

Background

Clostridium perfringens forms part of the human gut microbiota and has been associated with life-threatening necrotising enterocolitis (NEC) in premature infants. Whether specific toxigenic strains are responsible is unknown, as is the extent of diversity of strains in healthy premature babies. We investigated the C. perfringens carrier status of premature infants in the neonatal intensive care unit, factors influence this status, and the toxic potential of the strains.

Methods

C. perfringens was isolated by culture from faecal samples from 333 infants and their toxin gene profiles analysed by PCR. A survival analysis was used to identify factors affecting probability of carriage. Competitive growth experiments were used to explore the results of the survival analysis.

Results

29.4% of infants were colonized with C. perfringens before they left hospital. Three factors were inversely associated with probability of carriage: increased duration of maternal milk feeds, CPAP oxygen treatment and antibiotic treatment. C. perfringens grew poorly in breast milk and was significantly outperformed by Bifidobacterium infantis, whether grown together or separately. Toxin gene screening revealed that infants carried isolates positive for collagenase, perfringolysin O, beta 2, beta, becA/B, netB and enterotoxin toxin genes, yet none were observed to be associated with the development of NEC.

Conclusions

Approximately a third of preterm infants are colonised 3 weeks after birth with toxin gene-carrying C. perfringens. We speculate that increased maternal breast milk, oxygen and antibiotic treatment creates an environment in the gut hostile to growth of C. perfringens. Whilst potentially toxigenic C. perfringens isolates were frequent, no toxin type was associated with NEC.

Trial registration

clinicaltrials.govNCT01102738, registered 13th April 2010.

Bacteriemia por Clostridium sordellii en paciente con neoplasia gastrointestinal. Reporte de caso y revisión de literatura

La bacteriemia por Clostridium sordellii es infrecuente y usualmente se origina a partir de infecciones de etiología generalmente ginecológica y puerperal, con unamortalidad de aproximadamente el 70%. Existen pocas herramientas para el diagnóstico rápido y oportuno, siendo así la experiencia de tratamiento para este germen muy limitada en otros escenarios, lo que probablemente sea la causa de su alta mortalidad. Presentamos una paciente con antecedente de masa abdominal expansiva de larga data, con diagnóstico por histopatología e inmunohistoquimica compatibles con tumor del estroma gastrointestinal (GIST por sus siglas en inglés) y estudios de extensión que confirman compromiso metastásico hepático, en quien se documenta bacteriemia por Clostridium sordellii. 

Necrotizing Infections of the Hand and Wrist: Diagnosis and Treatment Options

Necrotizing infections of the hand and wrist are important clinical entities because of their rapidly progressive and potentially lethal nature. These infections encompass a spectrum of diseases with overlapping signs and symptoms, which can be subtle and nonspecific. If the brief prodromal period of these infections goes unrecognized, a local area of devitalized tissue can evolve into fulminant infection, multiorgan failure, and potentially death. Early recognition and treatment including administration of broad-spectrum antibiotics and surgical débridement are paramount to improving patient outcomes.

Treatment of Necrotizing Soft Tissue Infections: Antibiotics

Necrotizing soft tissue infections (NSTIs) are severe, life-threatening infections, and early therapeutic intervention is essential. Prompt administration of potent antimicrobial agents is pivotal, but inadequate empirical therapy is unfortunately common. Optimization of the antibiotic treatment strategy in NSTIs requires consideration of local epidemiology of causative pathogens and antimicrobial resistance patterns, knowledge on common pathogenetic mechanisms in NSTIs, and adaptations to pharmacokinetic and pharmacodynamic physiological changes in critically ill patients. In the present article we address all these issues, as well as review and compare contemporary guidelines for antimicrobial treatment of NSTIs from around the world.

Evidence for Infections by the Same Strain of Beta 2-toxigenic Clostridium perfringens Type A Acquired in One Hospital Ward

This study conducts a comparative phenotypic and genetic analysis of C. perfringens strains isolated from two patients hospitalized at the same time in 2017 in the surgical ward of the Provincial Specialist Hospital in Włocławek (Kujawsko-Pomorskie Province) who developed necrotizing soft tissue infections (NSTI). To explain the recurring cases of this infection, a comparative analysis was performed for these strains and the ones originating from infections recorded at the same hospital in three patients with gas gangrene in 2015. The two C. perfringens isolates studied in 2017 (8554/M/17 from patient No. 1 and 8567/M/17 from patient No. 2) had identical biochemical profiles. A comparison of research results using multiplex PCR from 2017 with a genetic analysis of strains from 2015 enabled us to demonstrate that the strains currently studied have the genes encoding the same toxins (α and β2) as the two strains analyzed in 2015: no. 7143 (patient No. 3) and no. 7149 (patient No. 2). A comparative analysis of the strain profiles obtained with pulsed-field gel electrophoresis (PFGE) in 2017 with the results from 2015 has found one identical and genetically unique restriction profile, corresponding to one clone of C. perfringens comprising of two strains: no. 8567/M/17 (patient No. 2 in 2017) and no. 7143 (patient No. 3 in 2015). The epidemiological data and detailed analysis of the course of both events suggest that this clone of C. perfringens possibly survived in adverse conditions of the external environment in the operating block of this hospital for many months.

Sporulation and Germination in Clostridial Pathogens

As obligate anaerobes, clostridial pathogens depend on their metabolically dormant, oxygen-tolerant spore form to transmit disease. However, the molecular mechanisms by which those spores germinate to initiate infection and then form new spores to transmit infection remain poorly understood. While sporulation and germination have been well characterized in Bacillus subtilis and Bacillus anthracis, striking differences in the regulation of these processes have been observed between the bacilli and the clostridia, with even some conserved proteins exhibiting differences in their requirements and functions. Here, we review our current understanding of how clostridial pathogens, specifically Clostridium perfringens, Clostridium botulinum, and Clostridioides difficile, induce sporulation in response to environmental cues, assemble resistant spores, and germinate metabolically dormant spores in response to environmental cues. We also discuss the direct relationship between toxin production and spore formation in these pathogens.