Non-encapsulated Bacteria Research Articles

C2 Deficiency Presenting as Pseudomonas Aeruginosa Bacteremia

C2 deficiency (C2D) is the most common homozygous complement deficiency, leading to susceptibility to infection with encapsulated bacteria due to defective opsonization. Pseudomonas aeruginosa is not a typical encapsulated bacterium, although reports have indicated that it can activate the complement system. Here we present an infant with Pseudomonas aeruginosa bacteremia who subsequently was diagnosed with C2D. Immunoglobulins, CH50, C2 level and function and C4 level were performed by the National Jewish Health Complement Laboratory and ARUP Laboratories. A 10-month-old Hispanic male with no significant past medical history presented to the hospital with a 2 day history of vomiting, diarrhea and fever to 102oF. Because of his progressive illness, he was admitted to the hospital for infectious workup. His blood culture grew Pseudomonas aeruginosa after 24hrs while urine and CSF cultures were negative. He was treated with ceftazidime without any complications. An immunodeficiency evaluation revealed normal immunoglobulin levels and normal sweat chloride test. His CH50 = 0 (60-144), C4 = 12 mg/dL (16-47), C2 = 2.8 mcg/mL (22.2-39.8), and C2 function = 21084 Units/mL (15354-46242). C2 levels for his father and mother were 15.1 and 16.9, respectively. C2D can present with Pseudomonas aeruginosa bacteremia. One study has demonstrated that the serum of a patient with C2 defect showed weak bactericidal activity against Pseudomonas aeruginosa strains as compared to normal serum. This case illustrates the importance of C2 in protecting from non-encapsulated bacteria that can evade the complement system. Complement system should be evaluated in patients with Pseudomonas bacteremia.

Enhanced vulnerability for Streptococcus pneumoniae sepsis during asplenia is determined by the bacterial capsule

Patients without a spleen are susceptible for overwhelming sepsis with Streptococcus pneumoniae. We investigated the relative contribution of the pneumococcal capsule in the reduced host defense after splenectomy.Sham-operated or splenectomized mice were inoculated with serotype 2 or 4 S. pneumoniae (D39, TIGR4) or the isogenic nonencapsulated mutants (D39Δcps, TIGR4Δcps). After splenectomy, intranasal infection with D39 resulted in increased mortality, increased bacterial dissemination and exaggerated systemic inflammation rather then altering inflammation in the lungs. Intravenous infection also resulted in enhanced mortality, bacterial growth and systemic inflammation after splenectomy. In contrast, the spleen did not contribute to host defense during infection with D39Δcps. Similar observations were made for TIGR4: increased bacterial growth and inflammation after intravenous infection with wild-type, but not nonencapsulated bacteria in splenectomized mice.These results indicate that the capsule of S. pneumoniae is indeed responsible for increased vulnerability of asplenic mice to invasive pneumococcal disease.

Effect of Microencapsulation on Viability of Lactobacillus acidophilus LA‐5 and Bifidobacterium bifidum BB‐12 During Kasar Cheese Ripening

The viability of encapsulated Lactobacillus acidophilus LA‐5 and Bifidobacterium bifidum BB‐12 by emulsion or extrusion techniques in Kasar cheese was investigated. The microbiological, biochemical and organoleptic properties of cheeses were assessed throughout 90‐day storage. Results showed that the viability of probiotic bacteria was maintained to a great extent by microencapsulation. No difference was noted between the two encapsulation techniques with regard to bacterial counts, proteolysis and organoleptical properties of the final products. Scalding caused a drastic decline in the counts of probiotic bacteria in all cheeses. Following scalding, while the numbers of nonencapsulated probiotic bacteria decreased continuously in the control cheese, the numbers of encapsulated bacteria remained well above the threshold for a minimum probiotic effect (107 cfu/g).

Differential lysis of sedimentary bacteria by Arenicola marina L.: examination of cell wall structure and exopolymeric capsules as correlates

Sedimentary bacteria are consumed and digested by deposit-feeding macroinvertebrates. Lysis of diverse strains of bacteria by deposit feeders may occur at different rates, thus altering the composition of bacteria in feces and surrounding sediments. The goals of this study were to determine whether various sedimentary bacterial isolates were equally susceptible to digestion by the digestive fluids of a model deposit feeder and to identify potential mechanisms of differential digestion. Specifically, cell wall type and exopolymeric capsule production were examined. We used a turbidimetric assay to compare the lytic susceptibilities of bacteria when exposed to digestive fluids collected from the deposit-feeding polychaete, Arenicola marina L.. Forty-three environmental isolates were tested under identical conditions. Significantly different bacteriolytic rates were observed ( P<0.0001, ANOVA); 74% of the strains were completely resistant to lysis, while the remaining strains exhibited varied rates of digestion. All gram-positive bacteria were resistant to lysis, while 31% of the gram-negative bacteria were susceptible. Using the G-test of independence (with William's correction) we rejected the null hypothesis that cell wall type and susceptibility were independent ( P<0.01). Approximately 88% of the strains tested produced capsules under our culture conditions. Twenty-four percent of the encapsulated bacteria were resistant to digestion, as compared to 20% of the non-encapsulated bacteria. The influence of encapsulation on resistance was not significant (0.75< P; G-test of independence). Although it cannot be concluded that encapsulation provides no protection against digestion for any bacterial strains, it was demonstrated that capsules do not necessarily confer resistance; this likely reflects the diversity of capsule chemistry and structure in various bacterial species. On the contrary, the strong relationship between cell wall type and lytic susceptibility may provide the ability to predict the fate of introduced bacteria to marine sediments. The demonstrated inefficiencies in digestion of bacteria by deposit feeders appear to be due to inherent differences in susceptibilities among bacterial strains, as opposed to physiological differences among individuals of all taxa.

Mechanisms of recurrent otitis media: importance of the immune response to bacterial surface antigens.

Otitis-prone children experience recurrent episodes of otitis media due to nontypeable H. influenzae (NTHI). A protective immune response occurs following infection, but this immune response is specific for the infecting strain, leaving the child susceptible to infection by other strains of NTHI. Little is known about the mechanism by which a strain-specific antibody response occurs to nonencapsulated bacteria. To explore the mechanism by which this strain-specific response occurs, animals were inoculated with whole bacterial cells and the antibody response was studied. The antibody response was predominantly directed to a highly strain-specific, immunodominant surface loop on the major outer membrane protein. This exquisitely restricted immune response leaves the host susceptible to recurrent infections by many strains of NTHI. The ability of the bacterium to direct the host to make a strain-specific antibody response has important implications in understanding the immune response to otitis media due to NTHI and in designing strategies for vaccine development.

Oral administration of Escherichia coli in enteric coated microparticles induces serum antibodies against lipopolysaccharide antigens

Heat-killed Escherichia coli O55:B5 were encapsulated in microcapsules coated with a pH-sensitive enteric coating (methacrylic acid copolymer). Oral immunization of C57BI/6 x DBA/2 (BDF1) mice with encapsulated bacteria resulted in a humoral immune response directed against bacterial lipopolysaccharide (LPS). This response was greatly boosted by a second series of immunization and differed both quantitatively and qualitatively from that induced by intraperitoneal immunization with non-encapsulated heat-killed bacteria. The anti-LPS response following oral immunization was comprised almost exclusively of IgG1 subclass antibodies and was highly specific for the LPS of the immunizing bacteria. The anti-LPS response following intraperitoneal immunization consisted mainly of IgM and IgG2a antibodies which were crossreactive with several bacterial strains. Our results demonstrate that whole killed bacteria, encapsulated by an enteric coating and administered orally, effectively induces an antibody response to LPS in mice which shows a typical memory response following secondary challenge.

Qualitative and quantitative immune response to bacterial capsular polysaccharides and their conjugates in mouse and man.

Capsular polysaccharides (CP), antigens present on the surfaces of Gram-negative and Gram-positive bacteria that cause invasive diseases, serve as bacterial virulence factors and protective antigens. Capsules have been shown to interfere with antibody binding and complement-mediated phagocytosis. In contrast, non-encapsulated bacteria activate complement and are rapidly cleared from the blood without the need for specific antibodies [28]. CP vaccines against several different bacterial pathogens have been successfully developed and are being used in sub-groups of the population who are at risk for infection [27]. Currently, several different CP conjugate vaccines are in development and clinical evaluation for active immunization and for the generation of antibodies for passive immunization. Development of these vaccines has involved the use of different conjugation methodologies and different carrier proteins. Further development of these vaccines will eventually result in the expansion of vaccination programs to include larger populations and the use of multivalent combined vaccines requiring a multiple injection vaccination regimen. In this paper, an overview of CP vaccines will be presented, as will a discussion of the issues that may arise as a result of the development of new vaccines. Possible strategies to resolve such issues will also be discussed.KeywordsCarrier ProteinConjugate VaccineCapsular PolysaccharideNeisseria MeningitidisDiphtheria ToxoidThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Effect of immune globulin intravenous on opsonization of bacteria by classic and alternative complement pathways in premature serum.

The mechanisms involved in the effect of immune globulin intravenous (IGIV) on bacterial opsonization by both complement pathways in premature serum were elucidated in this study. Of the bacteria used, Staphylococcus aureus and Salmonella enteritidis were nonencapsulated while Streptococcus pyogenes and Escherichia coli 07 K1 were encapsulated. As demonstrated by indirect immunofluorescence, IGIV showed specific antibody titers of 1:32 for S. aureus and S. enteritidis and of 1:8 for S. pyogenes and E. coli 07 K1. IGIV alone had no direct opsonic activity against these organisms. Addition of IGIV did not alter the opsonic activity of normal adult serum against these organisms. In contrast, addition of IGIV promoted the opsonic activity of premature serum against the nonencapsulated bacteria to levels matching that in normal adult serum. The IGIV preparation significantly improved the opsonization of bacteria by the classic (from 39 to 68% of that in adult serum) and alternative (from 22 to 97% of that in adult serum) complement pathways in premature serum. IGIV also markedly augmented C3 deposition on the bacteria by both complement pathways. These studies suggest that IGIV containing high titers of specific antibodies promote opsonization of bacteria by the enhancement of complement pathway activation, especially the alternative pathway, in premature serum.

The role of the spleen and splenic autotransplants in clearing experimental bacteremia caused by the gram-negative bacterium Escherichia coli.

Several clinical and laboratory studies have demonstrated the risk of sepsis in connection with encapsulated bacteria. The importance of clearing these organisms by the spleen is now well accepted. In contrast, the present work deals with the clearance of non-encapsulated gram-negative bacteria (Escherichia coli). The animals used for the experiments (a heterogeneous population of rabbits) were divided into a control group, a splenectomized group, and an autotransplanted group. The histological examination of the splenic transplants revealed typical splenic tissue including lymphatic follicles with germinal activity 42 days after transplantation. For estimation of the clearance capacity different amounts of bacteria were injected i.v. into the rabbits, and colony-forming bacterial cells in the blood were counted at certain intervals. In the control group no bacteria could be detected in the blood after 7 min. All animals of the splenectomized and autotransplanted groups showed a remarkable decrease in clearance efficiency (no bacteria in the blood after 19 min). No difference in the clearance kinetics could be shown between splenectomized and autotransplanted animals. Measuring the uptake of bacterial cells into different organs elicited low incorporation in the spleen as compared to non-immunocompetent organs, but no difference between normal spleen and splenic replants. However, saturation with E. coli cells reached higher limits in the normal spleen than in autotransplants. The immunologic capacity with respect to IgM-producing lymphocytes was measured by the hemolytic plaque assay. The results showed a severe malfunction of the autotransplants as compared to the normal spleen (only 2% of the activity of the control group). Vaccination against E. coli increased the clearance efficiency in all three groups. The data presented in this paper point out that several functions of the spleen cannot be carried out by autotransplants. The reasons, therefore, may be limited transplant mass and/or decreased specific functions.

A Comparison of the Mono- and Diphosphonucleotides of a Group C Streptococcus and Its Rough Variant

Abstract Group C Streptococcus pyogenes (M4) produces large amounts of hyaluronic acid in its capsule. Occasional nonencapsulated (rough) forms, which do not synthesize hyaluronic acid, appear spontaneously on blood agar plates and are sufficiently stable for study. The mono- and diphosphonucleotides found in cold perchloric acid extracts of the encapsulated and nonencapsulated streptococci have been separated on an anion exchange resin column and identified. With one exception, they are found in approximately equal amounts in both extracts. A large amount of one compound consistently appears in extracts of the nonencapsulated bacteria and is not found in extracts of the encapsulated bacteria. This compound has been identified as uridine diphosphate N-acetyl muramic acid.

細菌莢膜の電子顕微鏡的研究

In the 1st part, the author succeded in electron-microscopic observation of the capsule of Klebsiella pneumoniae. In the present part, by means of various experiments such as capsule swelling by immune sera, the author studied the characters of the bacterial capsule in detail. The results are briefly summarized as follows:1) The cells of Klebsiella pneumoniae cultured on broth agar still has a narrow capsule. By pouring immune sera, this capsule swells a little, and, at the same time, bacterial cell also somewhat swells making the borderbetween these two indistinct.2) The capsule of Klebsiella pneumoniae passed through the mouse shows marked swelling after addition of imune sera.3) To keep the capsular material as intact as possible, the following procedures were taken. Immune sera was directly dropped on bacterial colonics. a few minutes after this, bacterial cells float out, make the mesh with collodion membrane touch the floating cells. After lyophilizing thus obtained cells, the large capsule could be well observed electron-microscopically.4) A few minutes after addition of γ-globulin, the internal transparent layer of the capsular material of young culture can be observed more distictly: this is considered to be due to the retention of secretion by surrounding the cell with γ-grobulin.5) The capsular swelling could be also observed in Diplococcus pneumoniae, but could not in Bacillus anthracis; this needs further atudies.6) In some sorts of control non-encapsulated bacteria, these resuls could not be observed.From these observations, the author believes that the materials electron-microscopically observed are nothing but the bacterial capsule itself.