muramidase and Enterocolitis--Pseudomembranous

Clostridium difficile (also known as Peptoclostridium difficile) is a major nosocomial pathogen and a leading cause of antibiotic-associated diarrhea throughout the world. Colonization of the intestinal tract is necessary for C. difficile to cause disease. Host-produced antimicrobial proteins (AMPs), such as lysozyme, are present in the intestinal tract and can deter colonization by many bacterial pathogens, and yet C. difficile is able to survive in the colon in the presence of these AMPs. Our prior studies established that the Dlt pathway, which increases the surface charge of the bacterium by addition of d-alanine to teichoic acids, is important for C. difficile resistance to a variety of AMPs. We sought to determine what genetic mechanisms regulate expression of the Dlt pathway. In this study, we show that a dlt null mutant is severely attenuated for growth in lysozyme and that expression of the dltDABC operon is induced in response to lysozyme. Moreover, we found that a mutant lacking the extracytoplasmic function (ECF) sigma factor σ(V) does not induce dlt expression in response to lysozyme, indicating that σ(V) is required for regulation of lysozyme-dependent d-alanylation of the cell wall. Using reporter gene fusions and 5' RACE (rapid amplification of cDNA ends) analysis, we identified promoter elements necessary for lysozyme-dependent and lysozyme-independent dlt expression. In addition, we observed that both a sigV mutant and a dlt mutant are more virulent in a hamster model of infection. These findings demonstrate that cell wall d-alanylation in C. difficile is induced by lysozyme in a σ(V)-dependent manner and that this pathway impacts virulence in vivo.

Topics: Alanine; Animals; Bacterial Proteins; Carrier Proteins; Cell Wall; Clostridioides difficile; Cricetulus; Disease Models, Animal; Enterocolitis, Pseudomembranous; Female; Gene Expression Regulation, Bacterial; Host-Pathogen Interactions; Muramidase; Mutation; Operon; Promoter Regions, Genetic; Protein Isoforms; Sigma Factor; Signal Transduction; Stereoisomerism; Teichoic Acids; Virulence

Clostridium difficile is a clinically important pathogen and the most common cause of hospital-acquired infectious diarrhea. Expression of the C. difficile gene csfV, which encodes σ(V), an extracytoplasmic function σ factor, is induced by lysozyme, which damages the peptidoglycan of bacteria. Here we show that σ(V) is required for lysozyme resistance in C. difficile. Using microarray analysis, we identified the C. difficile genes whose expression is dependent upon σ(V) and is induced by lysozyme. Although the peptidoglycan of wild-type C. difficile is intrinsically highly deacetylated, we have found that exposure to lysozyme leads to additional peptidoglycan deacetylation. This lysozyme-induced deacetylation is dependent upon σ(V). Expression of pdaV, which encodes a putative peptidoglycan deacetylase, was able to increase lysozyme resistance of a csfV mutant. The csfV mutant strain is severely attenuated compared to wild-type C. difficile in a hamster model of C. difficile-associated disease. We conclude that the σ(V) signal transduction system, which senses the host innate immune defense enzyme lysozyme, is required for lysozyme resistance and is necessary during C. difficile infection.

Topics: Animals; Anti-Bacterial Agents; Clostridioides difficile; Cricetinae; Disease Models, Animal; DNA, Bacterial; Enterocolitis, Pseudomembranous; Microarray Analysis; Microbial Sensitivity Tests; Muramidase; Sigma Factor; Virulence

A study was made of some nonspecific immunity indices in staphylococcus sepsis and gastroenterocolitis during the infectious process in young children. Results of these investigations pointed to the depression of bactericidal and lysozyme activity of the blood serum and of the immunoadherence reaction at the acute period of the disease, and to some increase at the phase of recovery. There was also found an elevation of the phagocytic activity (of the phagocytolysis percentage) at the acute phase of the staphylococcus sepsis and gastroenterocolitis Antistaphylococcus gamma-globulin produced a positive effect on the lysozyme and bactericidal activity of the blood sera and promoted an increase of the blood phagocytic activity in the sick children.

Topics: Blood Bactericidal Activity; Enterocolitis, Pseudomembranous; Gastroenteritis; Immune Adherence Reaction; Male; Muramidase; Phagocytosis; Sepsis; Staphylococcal Infections

No microbial growth in platings of the gastric juice of patients with gastric ulcer and chronic anacidic gastritis was observed. It means that the absence of hydrochloric acid in the gastric juice does not deprive it of any antimicrobial action. The possible role of lysozyme in providing sterility of the proximal part of the gastro-intestinal tract was studied. Eighty patients with chronic diseases of the digestive organs were observed. It was noted that the levels of lysozyme in the gastric juice was high and markedly exceeded the maximum concentrations required for lysis of organisms most resistant to it. The maximum concentration was determined at pH of the gastric juice equal to 7.0-7.5 (265 gamma/ml+/-28). No lysozyme in the content of the duodenum and jejunal juice was found in most cases. Its presence in the above parts of the gastro-intestinal tract was mainly associated with microbial growth. The maximum concentration of lysozyme (40 gamma/ml) in the jejunal juice was observed in a female patient with chronic enterocolitis and significant microbial proliferation in the thin colon (more than 10(4) microbial bodies per 1 ml of the juice). Such parallelism between the presence of lysozyme in the gastric juice and microbial proliferation in it may be considered as a protective-adoptive reaction of the host.

Topics: Chronic Disease; Enterocolitis, Pseudomembranous; Gastric Juice; Gastritis; Hepatitis; Humans; Intestinal Secretions; Intestine, Small; Muramidase; Pancreatitis; Postgastrectomy Syndromes; Sterilization; Stomach Ulcer

Topics: Adult; Bacterial Infections; Biological Products; Complement System Proteins; Enterocolitis, Pseudomembranous; Female; Hepatitis A; Humans; Intestines; Leukocytes; Middle Aged; Muramidase; Prodigiosin; Sepsis; Staphylococcal Infections