scholarly journals Endotoxin, Capsule, and Bacterial Attachment Contribute to Neisseria meningitidis Resistance to the Human Antimicrobial Peptide LL-37

2009 ◽  
Vol 191 (12) ◽  
pp. 3861-3868 ◽  
Author(s):  
Allison Jones ◽  
Miriam Geörg ◽  
Lisa Maudsdotter ◽  
Ann-Beth Jonsson
Keyword(s):  
Antimicrobial Peptide ◽  
Neisseria Meningitidis ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Bacterial Attachment ◽  
Bacterial Membrane ◽  
Wild Type ◽  
Human Immune System ◽  
Sublethal Doses ◽  
Human Immune

ABSTRACT Pathogenic bacteria have evolved numerous mechanisms to evade the human immune system and have developed widespread resistance to traditional antibiotics. We studied the human pathogen Neisseria meningitidis and present evidence of novel mechanisms of resistance to the human antimicrobial peptide LL-37. We found that bacteria attached to host epithelial cells are resistant to 10 μM LL-37 whereas bacteria in solution or attached to plastic are killed, indicating that the cell microenvironment protects bacteria. The bacterial endotoxin lipooligosaccharide and the polysaccharide capsule contribute to LL-37 resistance, probably by preventing LL-37 from reaching the bacterial membrane, as more LL-37 reaches the bacterial membrane on both lipooligosaccharide-deficient and capsule-deficient mutants whereas both mutants are also more susceptible to LL-37 killing than the wild-type strain. N. meningitidis bacteria respond to sublethal doses of LL-37 and upregulate two of their capsule genes, siaC and siaD, which further results in upregulation of capsule biosynthesis.

Inhibition of Food-Related Pathogenic Bacteria by god-Transformed Penicillium nalgiovense Strains

1999 ◽  
Vol 62 (8) ◽  
pp. 940-943 ◽  
Author(s):  
ROLF GEISEN
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Activity ◽  
Type Strain ◽  
Salmonella Enteritidis ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Antibacterial Effect ◽  
Wild Type ◽  
Penicillium Nalgiovense ◽  
And Staphylococcus Aureus

Two strains of Penicillium nalgiovense, which carried the god gene of Aspergillus niger and had increased glucose oxidase (GOD) activity compared with the wild-type strain, were tested for their ability to suppress the growth of certain food-related pathogenic bacteria. In contrast to the wild type, which showed no antibacterial effect when grown in mixed culture with different bacteria, the two tranformed strains were highly antagonistic. The strain that expressed higher amounts of GOD in general had higher inhibitory activity. Both strains showed antibacterial activity against Listeria monocytogenes, Salmonella Enteritidis, and Staphylococcus aureus. The inhibitory activity was dependent on the glucose concentration in the medium. S. aureus was completely inhibited at 1% glucose in the presence of the higher GOD-producing transformant. In contrast, if arabinose was used as a carbon source, no inhibition occurred. If catalase was added to the medium, the inhibitory activity of the transformants was completely inactivated, indicating that the hydrogen peroxide produced was responsible for the antibacterial activity of the transformants.

scholarly journals Efficacy of Two Antibiotic-Extender Combinations on Mycoplasma bovis in Bovine Semen Production

Pathogens ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 808 ◽  
Author(s):  
Tarja Pohjanvirta ◽  
Nella Vähänikkilä ◽  
Henri Simonen ◽  
Sinikka Pelkonen ◽  
Tiina Autio
Keyword(s):  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Enrichment Culture ◽  
Contamination Level ◽  
Mycoplasma Bovis ◽  
Wild Type ◽  
Atcc Strain ◽  
Frozen Semen ◽  
Semen Extender ◽  
High Concentrations

Mycoplasma bovis is an important bovine pathogen. Artificial insemination (AI) using contaminated semen can introduce the agent into a naïve herd. Antibiotics, most often gentamycin, tylosin, lincomycin, spectinomycin (GTLS) combination are added to semen extender to prevent transmission of pathogenic bacteria and mycoplasmas. In a commercial AI straw production system with industrial scale procedures, we analyzed the mycoplasmacidal efficacy of GTLS and ofloxacin on M. bovis ATCC and wild type strain isolated from commercial AI straws. The strains were spiked at two concentrations (106 and 103 CFU/mL) into semen. Viable M. bovis in frozen semen straws was detected by enrichment culture and real-time PCR. We also compared different protocols to extract M. bovis DNA from spiked semen. None of the antibiotic protocols had any effect on the viability of either of the M. bovis strains at high spiking concentration. At low concentration, the wild type was inhibited by all other protocols, except low GTLS, whereas the ATCC strain was inhibited only by high GTLS. The InstaGene™ matrix was the most effective method to extract M. bovis DNA from semen. When there is a low M. bovis contamination level in semen, GTLS used at high concentrations, in accordance with Certified Semen Services requirements, is more efficient than GTLS used at concentrations stated in the OIE Terrestrial Code.

Boswellic acids target the human immune system-modulating antimicrobial peptide LL-37

2015 ◽  
Vol 102 ◽  
pp. 53-60 ◽  
Author(s):  
Arne Henkel ◽  
Lars Tausch ◽  
Max Pillong ◽  
Johann Jauch ◽  
Michael Karas ◽  
...  
Keyword(s):  
Immune System ◽  
Antimicrobial Peptide ◽  
Human Immune System ◽  
Boswellic Acids ◽  
Human Immune

scholarly journals Role of Lung Epithelial Cells in Defense against Klebsiella pneumoniae Pneumonia

2002 ◽  
Vol 70 (3) ◽  
pp. 1075-1080 ◽  
Author(s):  
Guadalupe Cortés ◽  
Dolores Álvarez ◽  
Carles Saus ◽  
Sebastián Albertí
Keyword(s):  
Epithelial Cells ◽  
Klebsiella Pneumoniae ◽  
Type Strain ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Capsular Polysaccharide ◽  
Defense Mechanism ◽  
Lung Epithelial Cells ◽  
Wild Type ◽  
Lung Epithelial

ABSTRACT The airway epithelium represents a primary site for the entry of pathogenic bacteria into the lungs. It has been suggested for many respiratory pathogens, including Klebsiella pneumoniae, that adhesion and invasion of the lung epithelial cells is an early stage of the pneumonia process. We observed that poorly encapsulated K. pneumoniae clinical isolates and an isogenic unencapsulated mutant invaded lung epithelial cells more efficiently than highly encapsulated strains independent of the K type. By contrast, the unencapsulated mutant was completely avirulent in a mouse model of pneumonia, unlike the wild-type strain, which produced pneumonia and systemic infection. Furthermore, the unencapsulated mutant bound more epithelially produced complement component C3 than the wild-type strain. Our results show that lung epithelial cells play a key role as a host defense mechanism against K. pneumoniae pneumonia, using two different strategies: (i) ingestion and control of the microorganisms and (ii) opsonization of the microorganisms. Capsular polysaccharide avoids both mechanisms and enhances the virulence of K. pneumoniae.

scholarly journals Lipooligosaccharide Structure Contributes to Multiple Steps in the Virulence of Neisseria meningitidis

2006 ◽  
Vol 74 (2) ◽  
pp. 1360-1367 ◽  
Author(s):  
Laura Plant ◽  
Johanna Sundqvist ◽  
Susu Zughaier ◽  
Lena Lövkvist ◽  
David S. Stephens ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Mouse Model ◽  
Neisseria Meningitidis ◽  
Type Strain ◽  
Lipid A ◽  
Wild Type Strain ◽  
Inner Core ◽  
Wild Type ◽  
Proinflammatory Response

ABSTRACT Lipooligosaccharide (LOS) of Neisseria meningitidis has been implicated in meningococcal interaction with host epithelial cells and is a major factor contributing to the human proinflammatory response to meningococci. LOS mutants of the encapsulated N. meningitidis serogroup B strain NMB were used to further determine the importance of the LOS structure in in vitro adherence and invasion of human pharyngeal epithelial cells by meningococci and to study pathogenicity in a mouse (CD46 transgenic) model of meningococcal disease. The wild-type strain [NeuNAc-Galβ-GlcNAc-Galβ-Glcβ-Hep2 (GlcNAc, Glcα) 3-deoxy-d-manno-2-octulosonic acid (KDO2)-lipid A; 1,4′ bisphosphorylated], although poorly adherent, rapidly invaded an epithelial cell layer in vitro, survived and multiplied early in blood, reached the cerebrospinal fluid, and caused lethal disease in the mouse model. In contrast, the Hep2 (GlcNAc) KDO2-lipid A (pgm) mutant, which was highly adherent to cultured epithelial cells, caused significantly less bacteremia and mortality in the mouse model. The Hep2-KDO2-lipid A (rfaK) mutant was shown to be moderately adherent and to cause levels of bacteremia and mortality similar to those caused by the wild-type strain in the mouse model. The KDO2-lipid A (gmhB) mutant, which lacks the heptose disaccharide in the inner core of LOS, avidly attached to epithelial cells but was otherwise avirulent. Disease development correlated with expression of specific LOS structures and was associated with lower adherence but rapid meningococcal passage to and survival in the bloodstream, induction of proinflammatory cytokines, and the crossing of the blood-brain barrier. Taken together, the results of this study further define the importance of the LOS structure as a virulence component involved in multiple steps in the pathogenesis of N. meningitidis.

scholarly journals Mechanisms of Bacterial (Serratia marcescens) Attachment to, Migration along, and Killing of Fungal Hyphae

2016 ◽  
Vol 82 (9) ◽  
pp. 2585-2594 ◽  
Author(s):  
Tal Hover ◽  
Tal Maya ◽  
Sapir Ron ◽  
Hani Sandovsky ◽  
Yana Shadkchan ◽  
...  
Keyword(s):  
Serratia Marcescens ◽  
Type Strain ◽  
Wild Type Strain ◽  
Bacterial Attachment ◽  
Wild Type ◽  
Bacterial Colony ◽  
Content Type ◽  
Fungal Hyphae ◽  
Bacterial Migration ◽  
Chitinase Genes

ABSTRACTWe have found a remarkable capacity for the ubiquitous Gram-negative rod bacteriumSerratia marcescensto migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota.S. marcescensmigration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well.S. marcescensdid not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony.S. marcescenscells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains ofS. marcescenswere able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion ofS. marcescenschitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by whichS. marcescensbinds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol.

Effect of combined oxidative and nitrosative stress on Neisseria meningitidis

2006 ◽  
Vol 34 (1) ◽  
pp. 197-199 ◽  
Author(s):  
K. Dyet ◽  
J. Moir
Keyword(s):  
Neisseria Meningitidis ◽  
Nitrosative Stress ◽  
Aetiological Agent ◽  
Nitrogen Species ◽  
Enteric Bacterium ◽  
Human Pathogens ◽  
Human Immune System ◽  
Oxidative And Nitrosative Stress ◽  
No Donor ◽  
Human Immune

Reactive oxygen and nitrogen species are produced by the human immune system in response to infection. Methods to detoxify these reactive species are vital to the survival of human pathogens, such as Neisseria meningitidis, which is the major aetiological agent of bacterial meningitis. Following activation, macrophages produce superoxide (O2−), hydrogen peroxide (H2O2) and nitric oxide (NO). The toxicity of O2−, generated using X/Xo (xanthine/xanthine oxidase), and H2O2 was investigated in the presence and absence of the NO donor DEA-NONOate [2-(N,N-diethylamino)-diazenolate-2-oxide diethylammonium salt]. Most of the toxicity from X/Xo was due to H2O2. In N. meningitidis, NO decreased the toxicity of the H2O2. In contrast, in the enteric bacterium Escherichia coli, NO increased the toxicity of the H2O2.

Pathogenic potential of a collagenase gene fromAeromonas veronii

2008 ◽  
Vol 54 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Hyun-Ja Han ◽  
Tatsuo Taki ◽  
Hidehiro Kondo ◽  
Ikuo Hirono ◽  
Takashi Aoki
Keyword(s):  
Mutant Strain ◽  
Type Strain ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Collagenolytic Activity ◽  
Bacterial Cells ◽  
Wild Type ◽  
Pathogenic Potential ◽  
Collagenase Gene

The role of collagenase as a mechanism of bacterial pathogenicity in some pathogenic bacteria has been reported. The information on the role of collagenase in Aeromonas spp. pathogenesis is scant. In the present study, a mutant Aeromonas veronii RY001 that is deficient in the putative collagenase gene acg was constructed and compared with the wild-type strain for virulence factors. Bacterial cells and cell-free extracellular products of the mutant had significantly less collagenolytic activity, but there were not significant differences in caseinolytic, gelatinolytic, and elastolytic activities. Adhesion and invasion abilities of the mutant strain on epithelioma papillosum of carp cells was only 56% of that of the wild-type strain, and the cytotoxicity of the mutant strain to epithelioma papillosum of carp cells was only 42% of that of the wild-type strain. The LD50values of the wild-type strain were determined as 1.6 × 106and 3.5 × 105cfu in goldfish and mice, respectively, whereas the mutant RY001 strain showed slightly higher values (i.e., 2.8 × 106and 1.4 × 106cfu in goldfish and mice, respectively). These results indicated the involvement of the collagenase gene in the pathogenesis of A. veronii.

scholarly journals The dlt Operon of Bacillus cereus Is Required for Resistance to Cationic Antimicrobial Peptides and for Virulence in Insects

2009 ◽  
Vol 191 (22) ◽  
pp. 7063-7073 ◽  
Author(s):  
Z. Abi Khattar ◽  
A. Rejasse ◽  
D. Destoumieux-Garzón ◽  
J. M. Escoubas ◽  
V. Sanchis ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Bacillus Cereus ◽  
Cell Walls ◽  
Type Strain ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Wild Type ◽  
Gram Positive ◽  
Cationic Antimicrobial Peptides ◽  
Humoral Immune

ABSTRACT The dlt operon encodes proteins that alanylate teichoic acids, the major components of cell walls of gram-positive bacteria. This generates a net positive charge on bacterial cell walls, repulsing positively charged molecules and conferring resistance to animal and human cationic antimicrobial peptides (AMPs) in gram-positive pathogenic bacteria. AMPs damage the bacterial membrane and are the most effective components of the humoral immune response against bacteria. We investigated the role of the dlt operon in insect virulence by inactivating this operon in Bacillus cereus, which is both an opportunistic human pathogen and an insect pathogen. The ΔdltBc mutant displayed several morphological alterations but grew at a rate similar to that for the wild-type strain. This mutant was less resistant to protamine and several bacterial cationic AMPs, such as nisin, polymyxin B, and colistin, in vitro. It was also less resistant to molecules from the insect humoral immune system, lysozyme, and cationic AMP cecropin B from Spodoptera frugiperda. ΔdltBc was as pathogenic as the wild-type strain in oral infections of Galleria mellonella but much less virulent when injected into the hemocoels of G. mellonella and Spodoptera littoralis. We detected the dlt operon in three gram-negative genera: Erwinia (Erwinia carotovora), Bordetella (Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica), and Photorhabdus (the entomopathogenic bacterium Photorhabdus luminescens TT01, the dlt operon of which did not restore cationic AMP resistance in ΔdltBc ). We suggest that the dlt operon protects B. cereus against insect humoral immune mediators, including hemolymph cationic AMPs, and may be critical for the establishment of lethal septicemia in insects and in nosocomial infections in humans.

scholarly journals Methionine Sulfoxide Reductase A (MsrA) Deficiency Affects the Survival of Mycobacterium smegmatis within Macrophages

2004 ◽  
Vol 186 (11) ◽  
pp. 3590-3598 ◽  
Author(s):  
T. Douglas ◽  
D. S. Daniel ◽  
B. K. Parida ◽  
C. Jagannath ◽  
S. Dhandayuthapani
Keyword(s):  
Mutant Strain ◽  
Mycobacterium Smegmatis ◽  
Type Strain ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Methionine Sulfoxide ◽  
Intracellular Survival ◽  
Methionine Sulfoxide Reductase ◽  
Wild Type ◽  
Methionine Sulfoxide Reductase A

ABSTRACT Methionine sulfoxide reductase A (MsrA) is an antioxidant repair enzyme which reduces oxidized methionine to methionine. Since oxidation of methionine in proteins impairs their function, an absence of MsrA leads to abnormalities in different organisms, including alterations in the adherence patterns and in vivo survival of certain pathogenic bacteria. To understand the role of MsrA in intracellular survival of bacteria, we disrupted the gene encoding MsrA in Mycobacterium smegmatis through homologous recombination. The msrA mutant strain of M. smegmatis exhibited significantly reduced intracellular survival in murine J774A.1 macrophages compared to the survival of its wild-type counterpart. Furthermore, immunofluorescence and immnunoblotting of phagosomes containing M. smegmatis strains revealed that the phagosomes with the msrA mutant strain acquired both p67phox of phagocyte NADPH oxidase and inducible nitric oxide synthase much earlier than the phagosomes with the wild-type strain. In addition, the msrA mutant strain of M. smegmatis was observed to be more sensitive to hydroperoxides than the wild-type strain was in vitro. These results suggest that MsrA plays an important role in both extracellular and intracellular survival of M. smegmatis.

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