muramidase and Bacteremia

In the current scenario of high antibiotic resistance, the search for therapeutic options against Pseudomonas aeruginosa must be approached from different perspectives: cell-wall biology as source of bacterial weak points and our immune system as source of weapons. Our recent study suggests that once the permeability barrier has been overcome, the activity of our cell-wall-targeting immune proteins is notably enhanced, more in mutants with impaired peptidoglycan recycling. The present work aims at analyzing the activity of these proteins [lysozyme and Peptidoglycan-Recognition-Proteins (PGLYRPs)], alone or with a permeabilizer (subinhibitory colistin) in clinical strains, along with other features related to the cell-wall. We compared the most relevant and complementary scenarios: acute (bacteremia) and chronic infections [early/late isolates from lungs of cystic fibrosis (CF) patients]. Although a low activity of lysozyme/PGLYRPs per se (except punctual highly susceptible strains) was found, the colistin addition significantly increased their activity regardless of the strains' colistin resistance levels. Our results show increased susceptibility in late CF isolates, suggesting that CF adaptation renders P. aeruginosa more vulnerable to proteins targeting the cell-wall. Thus, our work suggests that attacking some P. aeruginosa cell-wall biology-related elements to increase the activity of our innate weapons could be a promising therapeutic strategy.

Topics: Bacteremia; beta-Defensins; Cell Wall; Cystic Fibrosis; Cytokines; Humans; Immunity, Innate; Muramidase; Pseudomonas aeruginosa

Acinetobacter baumannii, a Gram-negative multidrug-resistant (MDR) bacterium, is now recognized as one of the more common nosocomial pathogens. Because most clinical isolates are found to be multidrug resistant, alternative therapies need to be developed to control this pathogen. We constructed a bacteriophage genomic library based on prophages induced from 13 A. baumannii strains and screened it for genes encoding bacteriolytic activity. Using this approach, we identified 21 distinct lysins with different activities and sequence diversity that were capable of killing A. baumannii. The lysin (PlyF307) displaying the greatest activity was further characterized and was shown to efficiently kill (>5-log-unit decrease) all tested A. baumannii clinical isolates. Treatment with PlyF307 was able to significantly reduce planktonic and biofilm A. baumannii both in vitro and in vivo. Finally, PlyF307 rescued mice from lethal A. baumannii bacteremia and as such represents the first highly active therapeutic lysin specific for Gram-negative organisms in an array of native lysins found in Acinetobacter phage.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Bacteremia; Biofilms; Drug Resistance, Multiple, Bacterial; Female; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Microbial Sensitivity Tests; Muramidase; Sepsis

Streptococcus pneumoniae is an important causative agent for bacteremia. Fluorescent in situ hybridization (FISH) is a helpful molecular technique for the rapid identification of S. pneumoniae in positive blood cultures. There are many reports concerning the application of an enzymatic treatment with lysozyme in the FISH procedure for partial cell wall digestion of S. pneumoniae. However, this study was aimed to test the FISH procedure without enzymatic treatment for the identification of S. pneumoniae in blood culture specimens. Seventy-seven positive blood culture specimens containing Gram-positive cocci were examined by both the conventional laboratory methods and FISH. Detection of S. pneumoniae was performed by two FISH procedures: one procedure was performed with an enzymatic treatment step and the other one was done without enzymatic treatment. In addition, the specimens were tested by the FISH procedure with enzymatic treatment to detect Streptococcus pyogenes and Enterococcus. The specificity of FISH in comparison with conventional culture methods was 100%. The sensitivity of the FISH procedure with enzymatic treatment for the detection of S. pneumoniae was 90%, whereas, the sensitivity of the FISH procedure without enzymatic treatment was 100%. In fact, by omission of enzymatic treatment, detection of S. pneumoniae was improved in 6 specimens. The results of the FISH and culture methods for the detection of S. pyogenes and Enterococcus were compatible. Altogether, FISH procedure without enzymatic treatment step seems to improve the detection of S. pneumoniae in some cases. Thus, for successful detection of S. pneumoniae, we suggest the application of both FISH procedures (the procedure with enzymatic treatment and the procedure without enzymatic treatment) for each blood culture specimen.

Topics: Bacteremia; Bacterial Typing Techniques; DNA Primers; Enterococcus; Humans; In Situ Hybridization, Fluorescence; Muramidase; Oligonucleotide Probes; Sensitivity and Specificity; Streptococcus pneumoniae; Streptococcus pyogenes

Cardiovascular dysfunction in septic shock (SS) is ascribed to the release of inflammatory mediators. Norepinephrine (NE) is often administered to treat low MAP in SS. We recently found that lysozyme c (Lzm-S) released from leukocytes was a mediator of myocardial depression in an Escherichia coil model of SS in dogs. This effect can be blocked in an in vitro preparation by chitobiose, a competitive inhibitor of Lzm-S. In the present study, we examined whether chitobiose treatment can reverse myocardial depression and obviate NE requirements in two respective canine E. coli preparations. In a 6-h study, we administered chitobiose after 3.5 h of E. coli bacteremia and compared stroke work (SW) and MAP at 6 h with a sepsis control group. In a 12-h study, we determined whether chitobiose treatment can reduce the need for NE requirements during 12 h of bacteremia. In the latter study, either chitobiose or NE was given when MAP decreased approximately 20% from the presepsis value in respective groups. In anesthetized, mechanically ventilated dogs, we monitored hemodynamic parameters during continuous E. coli infusion. In the 6-h study, chitobiose improved SW and MAP at the 6-h period as compared with the nontreated sepsis group. In the 12-h study, SW and MAP increased after chitobiose without the necessity of NE administration. These results suggest that inhibitors of Lzm-S such as chitobiose may improve myocardial depression and reduce the need for NE requirements in SS.

Topics: Animals; Bacteremia; Cardiomyopathies; Disaccharides; Dogs; Enzyme Inhibitors; Escherichia coli; Escherichia coli Infections; Humans; Inflammation Mediators; Male; Muramidase; Norepinephrine; Shock, Septic; Stroke Volume; Time Factors; Vasoconstrictor Agents

Streptococcus pneumoniae is becoming increasingly antibiotic resistant worldwide, and thus new antimicrobials are badly needed. We report the use of Cpl-1, the lytic enzyme of a pneumococcal bacteriophage, as an intravenous therapy for pneumococcal bacteremia in a mouse model. A 2000- microg dose of Cpl-1 reduced pneumococcal titers from a median of log(10) 4.70 CFU/ml to undetectable levels (

Topics: Animals; Anti-Bacterial Agents; Bacteremia; Disease Models, Animal; Drug Resistance, Bacterial; Enzyme Stability; Female; Hydrogen-Ion Concentration; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Muramidase; Nasopharynx; Pneumococcal Infections; Streptococcus Phages; Streptococcus pneumoniae

Phage-coded lysins, i.e. murein hydrolases, are enzymes that destroy the cell wall of bacteria. A rapid killing of Streptococcus pneumoniae in the nasopharynx of mice has been described recently using a phage-coded murein hydrolase (enzybiotic). The in vivo effects of a dose-ranging treatment, using either of the phage-coded lytic enzymes Cpl-1 lysozyme or the Pal amidase, have been investigated here in a murine sepsis model.. Purified Pal amidase and/or Cpl-1 lysozyme were used alone or in combination. These enzymes were injected intraperitoneally at different times after challenge with 5 x 10(7) cfu of a type 6B, antibiotic-resistant S. pneumoniae clinical isolate.. Animals challenged with 5 x 10(7) cfu of this strain alone died within 72 h, whereas a single intraperitoneal injection of Cpl-1 or Pal (200 microg; 1100 U) administered 1 h after the bacterial challenge was sufficient to effectively protect the mice, according to unpaired t-test (P<0.0001). Bacteraemia in unprotected mice reached colony counts >10(7) cfu/mL, whereas the mean colony count in lysin-protected animals was <10(6) cfu/mL over time and ultimately became undetectable. Interestingly, a synergic effect in vivo was observed with the combined use of 2.5 microg each of Cpl-1 and Pal.. Our findings suggest strongly that phage lysins protect animals from bacteraemia and death. Moreover, the simultaneous attack of the pneumococcal peptidoglycan by a lysozyme and an amidase leads to a remarkable effect through enhanced destruction of the bacterial cell wall. The benefits of therapy with enzybiotics against pneumococcus reported here might warrant the examination of alternative strategies for the treatment of diseases caused by clinically relevant pathogens.

Topics: Amidohydrolases; Animals; Anti-Bacterial Agents; Antibodies, Bacterial; Bacteremia; Bacteriophages; Blotting, Western; Cell Wall; Chromatography, DEAE-Cellulose; Drug Resistance, Bacterial; Drug Synergism; Female; Mice; Mice, Inbred BALB C; Muramidase; Pneumococcal Infections

Topics: Anti-Infective Agents, Local; Bacteremia; Child; Humans; Infant; Muramidase; Staphylococcal Infections