Papers by Vincent Fischetti
Antimicrobial Agents and Chemotherapy, 2019
The prevalence of multidrug-resistant Pseudomonas aeruginosa has stimulated development of altern... more The prevalence of multidrug-resistant Pseudomonas aeruginosa has stimulated development of alternative therapeutics. Bacteriophage peptidoglycan hydrolases, termed lysins, represent an emerging antimicrobial option for targeting Gram-positive bacteria.
PubMed, Oct 1, 1983
Using the Ouchterlony double diffusion and the crossed-immunoelectrophoresis techniques the react... more Using the Ouchterlony double diffusion and the crossed-immunoelectrophoresis techniques the reactivity to a purified extracellular product of nephritogenic group A streptococci (NASP) was examined with both acute and convalescent sera obtained from patients with documented post-streptococcal glomerulonephritis and patients with documented acute rheumatic fever. The streptococcal antigen utilized in these studies was first purified on SDS gels and then eluted from the gel, resulting in a single protein band on SDS electrophoresis. Double diffusion studies revealed that only nephritis patients reacted to this extracellular product associated with nephritogenic strains, whereas rheumatic fever sera produced no line of precipitation. An assay of serial bleedings from nephritis patients suggested that the antibody reactive to the NASP was in higher titre in the acute phase of the disease and decreased with convalescence. In confirmation of these findings, crossed-immunoelectrophoresis experiments were conducted with a battery of sera from acute nephritic and non-nephritic patients against the NASP antigen. A striking increase was detected in the reactivity of nephritis patients (96%) compared to non-nephritis sera (15-20%). Comparison between acute and convalescent sera using this technique confirmed the finding of decreasing antibody titre with resolution of disease. These findings of a specific humoral response in patients with acute post-streptococcal nephritis to the NASP of nephritogenic strains further implicates an aetiological function to this protein.
Clinical Infectious Diseases, 1989
Rayon and cotton fibers of the type used in the manufacture of tampons were extracted for 6 hours... more Rayon and cotton fibers of the type used in the manufacture of tampons were extracted for 6 hours in isopropyl alcohol in a soxhlet apparatus to remove all finishes from the fiber surface. The fibers were used to produce experimental tampons of commercial design. Using a syringe method, the tampons were saturated with diluted staphylococci in brain-heart infusion medium and incubated at 37 degrees C. Spent medium was expressed from the tampons and analyzed for growth of staphylococci and production of toxic shock syndrome toxin 1 (TSST-1). Results revealed no statistical difference in the production of TSST-1 by cells grown in rayon or cotton. However, a significant increase in TSST-1 production was observed in tampon cultures when compared with medium controls. When similar experiments were performed with tampons saturated with nitrogen, a significant decrease in TSST-1 production was observed when compared with air-saturated tampons. The results indicate that the oxygen normally present in tampons plays a significant role in modulating the production of TSST-1.
Microbiology spectrum, Jul 19, 2019
As arms, legs, hair, and fur are used in higher species for their survival in the environment, su... more As arms, legs, hair, and fur are used in higher species for their survival in the environment, surface appendages are used by bacteria for similar purposes. Surface molecules in bacteria range from complex structures such as flagella that propel the organism in aqueous environments, to less sophisticated polysaccharides and proteins. All of these molecules serve to benefit the organism for survival in a hostile environment, such as the waters of a rushing stream, the blood of an infected animal, the surface of an object, or the surface of a mucosal epithelium. Although it was previously believed that bacteria were simple single-cell organisms with little complexity, it is now apparent that they are highly evolved, advanced particles that possess a wide array of surface molecules that serve to manipulate the organism in its environment. For human pathogens, surface molecules have been finely tuned to allow adherence and colonization of host surfaces, invasion of cells, evasion of the host's immune response, and persistence in infected tissues. In an effort to emphasize the complexity of bacterial surface molecules and their use in the everyday life of the bacterium, this chapter will focus on those surface proteins found on grampositive bacteria. For an extensive review of the subject, see references (1, 2). GRAM-POSITIVE CELL WALL From electron microscopic analysis of the gram-positive cell envelope (see chapter 1, this volume) and a number of elegant chemical, structural and immunological analyses, a picture of the gram-positive cell wall has emerged (Fig. 1). The structure differs significantly from the gram-negative cell wall in two ways: (i) the presence of a thicker and more cross-linked peptidoglycan and (ii) the lack of an outer membrane. Because of these differences, surface molecules on gram-positive organisms vary from those on gram-negative organisms, requiring specialized systems to transport and anchor molecules through the outer membrane(3, 4). In general, surface proteins in gram-positive bacteria can be separated into three categories: (i) those that anchor at their C-terminal ends (through an LPxTG motif), (ii) those that bind by way of charge or hydrophobic interactions, and (iii) those that bind via their N-terminal region (lipoproteins) (Fig. 1).
ASM Press eBooks, Mar 3, 2006
... GUIDO WERNER 32 The Staphylococcus aureus NCTC 8325 Genome/381 ALLISON F. GILLASPY, VERONICA ... more ... GUIDO WERNER 32 The Staphylococcus aureus NCTC 8325 Genome/381 ALLISON F. GILLASPY, VERONICA WORRELL, JOSHUA ... and Pathogenicity of Staphylococci Other than Staphylococcus aureus and Staphylococcus epidermidis/572 ANNE TRISTAN, GERARD LINA ...
Frontiers in Microbiology, 2022
Most skin infections, including those complicating burns, are polymicrobial involving multiple ca... more Most skin infections, including those complicating burns, are polymicrobial involving multiple causative bacteria. Add to this the fact that many of these organisms may be antibiotic-resistant, and a simple skin lesion or burn could soon become life-threatening. Membrane-acting cationic peptides from Gram-negative bacteriophage lysins can potentially aid in addressing the urgent need for alternative therapeutics. Such peptides natively constitute an amphipathic region within the structural composition of these lysins and function to permit outer membrane permeabilization in Gram-negative bacteria when added externally. This consequently allows the lysin to access and degrade the peptidoglycan substrate, resulting in rapid hypotonic lysis and bacterial death. When separated from the lysin, some of these cationic peptides kill sensitive bacteria more effectively than the native molecule via both outer and cytoplasmic membrane disruption. In this study, we evaluated the antibacterial p...
Nature Microbiology, 2021
CRISPR loci are composed of short DNA repeats separated by sequences, known as spacers, that matc... more CRISPR loci are composed of short DNA repeats separated by sequences, known as spacers, that match the genomes of invaders such as phages and plasmids. Spacers are transcribed and processed to generate RNA guides used by CRISPR-associated nucleases to recognize and destroy the complementary nucleic acids of invaders. To counteract this defence, phages can produce small proteins that inhibit these nucleases, termed anti-CRISPRs (Acrs). Here we demonstrate that the ΦAP1.1 temperate phage utilizes an alternative approach to antagonize the type II-A CRISPR response in Streptococcus pyogenes. Immediately after infection, this phage expresses a small anti-CRISPR protein, AcrIIA23, that prevents Cas9 function, allowing ΦAP1.1 to integrate into the direct repeats of the CRISPR locus, neutralizing immunity. However, acrIIA23 is not transcribed during lysogeny and phage integration/excision cycles can result in the deletion and/or transduction of spacers, enabling a complex modulation of the type II-A CRISPR immune response. A bioinformatic search identified prophages integrated not only in the CRISPR repeats, but also the cas genes, of diverse bacterial species, suggesting that prophage disruption of the CRISPR-cas locus is a recurrent mechanism to counteract immunity.
Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.
Streptococcal diseases have been recognized in recorded history for over two thousand years and r... more Streptococcal diseases have been recognized in recorded history for over two thousand years and remain today as a serious cause of worldwide health problems. Early research revealed that the streptococci were not only among the first organisms thought to be the cause of contagious diseases, but their presence initiated the introduction of cleanliness and the use of sterile procedures into hospital settings. More recent research on streptococci demonstrated that the hereditary material was DNA, paving the way to present day molecular and genomic studies. This book is focused on one of the streptococci, Streptococcus pyogenes (the group A Streptococcus), the bacteria responsible for diseases, such as scarlet fever, pharyngitis, impetigo, cellulitis, necrotizing fasciitis and toxic shock syndrome, as well as the sequelae of rheumatic fever and acute poststreptococcal glomerulonephritis. The goal of the 30 chapters in this volume is to present an up to date and comprehensive review of r...
SummaryCRISPR loci are composed of short DNA repeats separated by sequences that match the genome... more SummaryCRISPR loci are composed of short DNA repeats separated by sequences that match the genomes of phages and plasmids, known as spacers. Spacers are transcribed and processed to generate RNA guides used by CRISPR-associated nucleases to recognize and destroy the complementary nucleic acids of invaders. To counteract this defense, phages can produce small proteins that inhibit these nucleases. Here we demonstrate that the ΦAP1.1 temperate phage utilizes an alternate approach to antagonize the type II-A CRISPR response in Streptococcus pyogenes. Immediately after infection this phage expresses a canonical anti-CRISPR, AcrIIA23 that prevents Cas9 function, allowing ΦAP1.1 to integrate into the direct repeats of the CRISPR locus and neutralizing immunity. However, acrIIA23 is not transcribed during lysogeny and phage integration/excision cycles can result in the deletion and/or transfer of spacers, enabling a complex modulation of the type II-A CRISPR immune response.
Biology and Applications, 2004
Practical Handbook of Microbiology, Third Edition, 2015
Gram-Positive Pathogens, Second Edition
ABSTRACT Streptococcal pharyngitis (or strep throat) is a common childhood disease affecting mill... more ABSTRACT Streptococcal pharyngitis (or strep throat) is a common childhood disease affecting millions of children each year, but it is one of the only childhood diseases for which a vaccine does not exist. While for decades the development of a vaccine has been the center of attention in many laboratories worldwide, with some successes, no corporate development has yet to be initiated. The reason for this probably lies in our inability to conclusively identify the streptococcal molecule or molecules responsible for the heart cross-reactive antibodies observed in the serum of rheumatic fever patients. Without this specific knowledge, any streptococcal vaccine antigen is suspect and thus not the target for a billion-dollar investment, despite the fact that the exact role of cross-reactive antibodies in rheumatic fever is still questionable. This article will describe the development of several approaches to protect against Streptococcus pyogenes infections over the past several decades.
Practical Handbook of Microbiology, Second Edition, 2008
The Journal of experimental medicine, 1992
The surface of streptococci presents an array of different proteins, each designed to perform a s... more The surface of streptococci presents an array of different proteins, each designed to perform a specific function. In an attempt to understand the early events in group A streptococci infection, we have identified and purified a major surface protein from group A type 6 streptococci that has both an enzymatic activity and a binding capacity for a variety of proteins. Mass spectrometric analysis of the purified molecule revealed a monomer of 35.8 kD. Molecular sieve chromatography and sodium dodecyl sulfate (SDS)-gel electrophoresis suggest that the native conformation of the protein is likely to be a tetramer of 156 kD. NH2-terminal amino acid sequence analysis revealed 83% homology in the first 18 residues and about 56% in the first 39 residues with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of eukaryotic or bacterial origin. This streptococcal surface GAPDH (SDH) exhibits a dose-dependent dehydrogenase activity on glyceraldehyde-3-phosphate in the presence of beta-nicotinami...
Antimicrobial Agents and Chemotherapy, 2019
Multidrug resistance (MDR) is rapidly increasing in prevalence among isolates of the opportunisti... more Multidrug resistance (MDR) is rapidly increasing in prevalence among isolates of the opportunistic pathogen Pseudomonas aeruginosa , leaving few treatment options. Phage lysins are cell wall hydrolases that have a demonstrated therapeutic potential against Gram-positive pathogens; however, the outer membrane of Gram-negative bacteria prevents most lysins from reaching the peptidoglycan, making them less effective as therapeutics.
Clinical infectious …, 1998
In spite of 50 years of extensive use of penicillin, group A streptococci remain exquisitely susc... more In spite of 50 years of extensive use of penicillin, group A streptococci remain exquisitely susceptible to this antibiotic. This observation that continuing susceptibility has occurred despite the development of resistance to other antimicrobial agents prompted a day-long meeting at Rockefeller University (New York) in October 1996. Among the most likely explanations for this remarkable state of continued susceptibility to penicillin are that b-lactamase may not be expressed or may be toxic to the organism and/or that low-affinity penicillin-binding proteins either are not expressed or render organisms nonviable. Other potential explanations are that circumstances favorable for the development of resistance have not yet occurred and/or that there are inefficient mechanisms for or barriers to genetic transfer. Recommended future actions include (1) additional laboratory investigations of gene transfer, penicillin-binding proteins, virulence factors, and homeologous recombination and mismatch repair; (2) increased surveillance for the development of penicillin resistance; (3) application of bioinformatics to analyze streptococcal genome sequences; and (4) development of vaccines and novel antimicrobial agents. Thus far the susceptibility of group A streptococci to penicillin has not been a major clinical or epidemiological problem. A similar observation, however, could have been made decades ago about Streptococcus pneumoniae. It is therefore vital for the scientific community to closely examine why penicillin has remained uniformly highly active against group A streptococci in order to maintain this desirable state.
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Papers by Vincent Fischetti