scholarly journals Metabolism of pyrithiamine by the pyrithiamine-requiring mutant of Staphylococcus aureus

1968 ◽  
Vol 107 (2) ◽  
pp. 165-169 ◽  
Author(s):  
Asru K. Sinha ◽  
G. C. Chatterjee
Keyword(s):  
Staphylococcus Aureus ◽  
Mutant Strain ◽  
Parent Strain ◽  
Culture Broth ◽  
Exponential Phase ◽  
Optimum Growth ◽  
Solvent Fractionation ◽  
Prolonged Incubation ◽  
Inhibition Index

1. A mutant strain of Staphylococcus aureus that requires pyrithiamine for its optimum growth was found to utilize pyrithiamine during the exponential phase of growth. 2. Pyrithiamine was deaminated by the organism to form oxypyrithiamine, the reaction being enzymic with no cofactor requirement. 3. On prolonged incubation of S. aureus A cultures, the concentration of deaminating enzyme increased in the culture broth, from which pyrithiamine-deaminating enzyme could be isolated by solvent fractionation. 4. Oxypyrithiamine is not a competitive analogue of thiamine although it inhibited the growth of the parent strain of S. aureus; the inhibition index of this compound, however, was lower than that of pyrithiamine.

scholarly journals Staphylococcus aureus growth delay after exposure to low fluencies of blue light (470 nm)

2020 ◽  
Author(s):  
I. D. C. Galo ◽  
B. E. De Lima ◽  
T. G. Santos ◽  
A. Braoios ◽  
R. P. Prado ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Blue Light ◽  
Bacterial Infections ◽  
Growth Delay ◽  
Control Group ◽  
Prolonged Incubation ◽  
Bacterial Cultures ◽  
Experimental Approaches ◽  
Prolonged Hospital

Abstract Antibiotic resistance is one of the greatest challenges to treat bacterial infections worldwide, leading to increase in medical expenses, prolonged hospital stay and increased mortality. The use of blue light has been suggested as an innovative alternative to overcome this problem. In this study we analyzed the antibacterial effect of blue light using low emission parameters on Staphylococcus aureus cultures. In vitro bacterial cultures were used in two experimental approaches. The first approach included single or fractionated blue light application provided by LED emitters (470 nm), with the following fluencies: 16.29, 27.16 and 54.32 J/cm2. For the second approach a power LED (470 nm) was used to deliver 54.32 J/cm2 fractionated in 3 applications. Our results demonstrated that bacterial cultures exposed to fractionated blue light radiation exhibited significantly smaller sizes colonies than the control group after 24 h incubation, however the affected bacteria were able to adapt and continue to proliferate after prolonged incubation time. We could conclude that the hypothetical clinical use of low fluencies of blue light as an antibacterial treatment is risky, since its action is not definitive and proves to be ineffective at least for the strain used in this study.

scholarly journals The Nature of Antibacterial Adaptive Immune Responses against Staphylococcus aureus Is Dependent on the Growth Phase and Extracellular Peptidoglycan

2019 ◽  
Vol 88 (1) ◽  
Author(s):  
Payal P. Balraadjsing ◽  
Lisbeth D. Lund ◽  
Yuri Souwer ◽  
Sebastian A. J. Zaat ◽  
Hanne Frøkiær ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
T Cell ◽  
Stationary Phase ◽  
Growth Phase ◽  
Cell Response ◽  
Th17 Cell ◽  
Exponential Phase ◽  
Th1 Cell ◽  
Content Type

ABSTRACT Staphylococcus aureus has evolved different strategies to evade the immune response, which play an important role in its pathogenesis. The bacteria express and shed various cell wall components and toxins during different stages of growth that may affect the protective T cell responses to extracellular and intracellular S. aureus. However, if and how the dendritic cell (DC)-mediated T cell response against S. aureus changes during growth of the bacterium remain elusive. In this study, we show that exponential-phase (EP) S. aureus bacteria were endocytosed very efficiently by human DCs, and these DCs strongly promoted production of the T cell polarizing factor interleukin-12 (IL-12). In contrast, stationary-phase (SP) S. aureus bacteria were endocytosed less efficiently by DCs, and these DCs produced small amounts of IL-12. The high level of IL-12 production induced by EP S. aureus led to the development of a T helper 1 (Th1) cell response, which was inhibited after neutralization of IL-12. Furthermore, preincubation with the staphylococcal cell wall component peptidoglycan (PGN), characteristically shed during the exponential growth phase, modulated the DC response to EP S. aureus. PGN preincubation appeared to inhibit IL-12p35 expression, leading to downregulation of IL-12 and an increase of IL-23 production by DCs, enhancing Th17 cell development. Taken together, our data indicate that exponential-phase S. aureus bacteria induce a stronger IL-12-dependent Th1 cell response than stationary-phase S. aureus and that this Th1 cell response shifted toward a Th17 cell response in the presence of PGN.

scholarly journals Extracellular Adherence Protein from Staphylococcus aureus Enhances Internalization into Eukaryotic Cells

2003 ◽  
Vol 71 (5) ◽  
pp. 2310-2317 ◽  
Author(s):  
Axana Haggar ◽  
Muzaffar Hussain ◽  
Helena Lönnies ◽  
Mathias Herrmann ◽  
Anna Norrby-Teglund ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mutant Strain ◽  
Plasma Proteins ◽  
Binding Capacity ◽  
Clinical Isolates ◽  
Eukaryotic Cells ◽  
Isogenic Mutant ◽  
Bacterial Surface ◽  
Internalization Process ◽  
Surface Localization

ABSTRACT In this study we have shown that Eap (extracellular adherence protein) plays a role in the internalization process of Staphylococcus aureus into eukaryotic cells. Eap is a protein that is mostly extracellularly and to a lesser extent is bound to the bacterial surface as a result of rebinding. Eap is able to bind to several plasma proteins, such as fibronectin, fibrinogen, and prothrombin. It has the capacity to form oligomers and is able to agglutinate S. aureus. A mutant strain, Newman mAH12 (eap:: Eryr), with a deficient eap gene was used in the present study. We have demonstrated that (i) strain Newman mAH12 could adhere to and become internalized to a higher extent by eukaryotic cells than the isogenic mutant, (ii) strain Newman mAH12 complemented with the eap gene displayed restoration of the internalization level, (iii) externally added Eap enhanced the internalization of laboratory and clinical S. aureus strains as well as of S. carnosus (a coagulase-negative species devoid of proteins important for internalization), and (iv) antibodies against Eap were able to block the internalization process in strain Newman mAH12 and clinical isolates. Eap, with its broad binding capacity and its surface localization, thus seems to contribute to the internalization of S. aureus into eukaryotic cells. We therefore propose a novel internalization pathway for S. aureus in which Eap plays an enhancing role.

scholarly journals Characterization of a Second Rhodococcus erythropolis SQ1 3-Ketosteroid 9α-Hydroxylase Activity Comprising a Terminal Oxygenase Homologue, KshA2, Active with Oxygenase-Reductase Component KshB

2008 ◽  
Vol 74 (23) ◽  
pp. 7197-7203 ◽  
Author(s):  
R. van der Geize ◽  
G. I. Hessels ◽  
M. Nienhuis-Kuiper ◽  
L. Dijkhuizen
Keyword(s):  
Mutant Strain ◽  
Parent Strain ◽  
Gene Deletion ◽  
Amino Acid Level ◽  
Rhodococcus Erythropolis ◽  
Pcr Primers ◽  
Transcriptional Analysis ◽  
Reporter Protein ◽  
Steroid Substrate ◽  
Key Enzyme

ABSTRACT Previously we have characterized 3-ketosteroid 9α-hydroxylase (KSH), a key enzyme in microbial steroid degradation in Rhodococcus erythropolis strain SQ1, as a two-component iron-sulfur monooxygenase, comprised of the terminal oxygenase component KshA1 and the oxygenase-reductase component KshB. Deletion of the kshA1 gene resulted in the loss of the ability of mutant strain RG2 to grow on the steroid substrate 4-androstene-3,17-dione (AD). Here we report characteristics of a close KshA1 homologue, KshA2 of strain SQ1, sharing 60% identity at the amino acid level. Expression of the kshA2 gene in mutant strain RG2 restored growth on AD and ADD, indicating that kshA2 also encodes KSH activity. The functional complementation was shown to be dependent on the presence of kshB. Transcriptional analysis showed that expression of kshA2 is induced in parent strain R. erythropolis SQ1 in the presence of AD. However, promoter activity studies, using β-lactamase of Escherichia coli as a convenient transcription reporter protein for Rhodococcus, revealed that the kshA2 promoter in fact is highly induced in the presence of 9α-hydroxy-4-androstene-3,17-dione (9OHAD) or a metabolite thereof. Inactivation of kshA2 in parent strain SQ1 by unmarked gene deletion did not affect growth on 9OHAD, cholesterol, or cholic acid. We speculate that KshA2 plays a role in preventing accumulation of toxic intracellular concentrations of ADD during steroid catabolism. A third kshA homologue was additionally identified in a kshA1 kshA2 double gene deletion mutant strain of R. erythropolis SQ1. The developed degenerate PCR primers for kshA may be useful for isolation of kshA homologues from other (actino) bacteria.

scholarly journals PBP5, PBP6 and DacD play different roles in intrinsic β-lactam resistance of Escherichia coli

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2702-2707 ◽  
Author(s):  
Sujoy Kumar Sarkar ◽  
Mouparna Dutta ◽  
Chiranjit Chowdhury ◽  
Akash Kumar ◽  
Anindya S. Ghosh
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Parent Strain ◽  
Amino Acid Identity ◽  
Enzymic Activity ◽  
Exponential Phase ◽  
Wild Type ◽  
Acid Identity ◽  
Penicillin Binding Proteins ◽  
E Coli

Escherichia coli PBP5, PBP6 and DacD, encoded by dacA, dacC and dacD, respectively, share substantial amino acid identity and together constitute ~50 % of the total penicillin-binding proteins of E. coli. PBP5 helps maintain intrinsic β-lactam resistance within the cell. To test if PBP6 and DacD play simlar roles, we deleted dacC and dacD individually, and dacC in combination with dacA, from E. coli 2443 and compared β-lactam sensitivity of the mutants and the parent strain. β-Lactam resistance was complemented by wild-type, but not dd-carboxypeptidase-deficient PBP5, confirming that enzymic activity of PBP5 is essential for β-lactam resistance. Deletion of dacC and expression of PBP6 during exponential or stationary phase did not alter β-lactam resistance of a dacA mutant. Expression of DacD during mid-exponential phase partially restored β-lactam resistance of the dacA mutant. Therefore, PBP5 dd-carboxypeptidase activity is essential for intrinsic β-lactam resistance of E. coli and DacD can partially compensate for PBP5 in this capacity, whereas PBP6 cannot.

scholarly journals THE OCCURRENCE OF PEROXIDE IN CULTURES OF PNEUMOCOCCUS

1924 ◽  
Vol 39 (2) ◽  
pp. 275-287 ◽  
Author(s):  
Oswald T. Avery ◽  
Hugh J. Morgan
Keyword(s):  
Staphylococcus Aureus ◽  
Culture Fluid ◽  
Logarithmic Phase ◽  
Free Access ◽  
Anaerobic Conditions ◽  
Peroxide Formation ◽  
Acid Media ◽  
Prolonged Incubation ◽  
Catalase Peroxidase ◽  
Favorable Conditions

1. Conditions which favor the formation and accumulation of peroxide in broth cultures of pneumococcus are free access of air, and the absence of catalase, peroxidase, and other catalysts capable of decomposing this compound. Under these favorable conditions peroxide becomes demonstrable in the culture fluid during the logarithmic phase of growth and persists for a period of at least 6 to 12 days. 2. In the absence of these favorable conditions the formation of peroxide is inhibited. In a culture with deficient oxygen exposure the accumulation of peroxide is delayed; when anaerobic conditions are maintained the substance is not formed. In the presence of active catalysts, peroxide does not accumulate in the medium in quantities sufficient to give a positive reaction. The accumulation of peroxide in pneumococcus cultures is dependent upon the balance between the amount produced by the microorganisms and the amount destroyed by substances in the medium. 3. The peroxide formed in pneumococcus cultures is unstable. It gradually disappears during prolonged incubation at 37°C.; it is less stable in alkaline than in neutral or acid media. It is destroyed in culture filtrates exposed to the temperature of boiling water for 15 minutes, and to that of steam under pressure (15 pounds) for 10 minutes. 4. Peroxide formation occurred early in broth cultures of the seven strains of pneumococcus and of the six strains of non-hemolytic streptococci studied. Fifteen of twenty-three strains of Streptococcus hæmolyticus and one of three strains of Streptococcus mucosus formed peroxide. In the positively reacting cultures of Streptococcus hæmolyticus and Streptococcus mucosus the presence of peroxide was not demonstrable until the 3rd to 5th day of incubation. Peroxide could not be detected at any time during growth of the two strains of Staphylococcus aureus.

scholarly journals Accessory Gene Regulator (agr) Locus in Geographically Diverse Staphylococcus aureus Isolates with Reduced Susceptibility to Vancomycin

2002 ◽  
Vol 46 (5) ◽  
pp. 1492-1502 ◽  
Author(s):  
George Sakoulas ◽  
George M. Eliopoulos ◽  
Robert C. Moellering ◽  
Christine Wennersten ◽  
Lata Venkataraman ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Parent Strain ◽  
Point Mutations ◽  
Loss Of Function ◽  
Accessory Gene ◽  
Accessory Gene Regulator ◽  
Geographic Origins ◽  
Group Ii ◽  
Null Strain

ABSTRACT The majority of infections with glycopeptide intermediate-level resistant Staphylococcus aureus (GISA) originate in biomedical devices, suggesting a possible increased ability of these strains to produce biofilm. Loss of function of the accessory gene regulator (agr) of S. aureus has been suggested to confer an enhanced ability to bind to polystyrene. We studied agr in GISA, hetero-GISA, and related glycopeptide-susceptible S. aureus isolates. All GISA strains from diverse geographic origins belong to agr group II. All GISA strains were defective in agr function, as demonstrated by their inability to produce delta-hemolysin. Hetero-GISA isolate A5940 demonstrated a nonsense mutation in agrA that was not present in a pulsed-field gel electrophoresis-indistinguishable vancomycin-susceptible isolate from the same patient. Various other agr point mutations were noted in several clinical GISA and hetero-GISA isolates. A laboratory-generated agr-null strain demonstrated a small but reproducible increase in vancomycin heteroresistance after growth in vitro in subinhibitory concentrations of vancomycin. This was not seen in the isogenic agr group II parent strain in which agr was intact. The in vitro bactericidal activity of vancomycin was attenuated in the agr-null strain compared to the parent strain. These findings imply that compromised agr function is advantageous to clinical isolates of S. aureus toward the development of vancomycin heteroresistance, perhaps through the development of vancomycin tolerance.

scholarly journals Loss of Catabolite Repression Function of HPr, the Phosphocarrier Protein of the Bacterial Phosphotransferase System, Affects Expression of the cry4A Toxin Gene in Bacillus thuringiensis subsp. israelensis

2002 ◽  
Vol 184 (19) ◽  
pp. 5410-5417 ◽  
Author(s):  
Sharik R. Khan ◽  
Nirupama Banerjee-Bhatnagar
Keyword(s):  
Bacillus Thuringiensis ◽  
Mutant Strain ◽  
Catabolite Repression ◽  
Parent Strain ◽  
Inhibitory Effect ◽  
Toxin Gene ◽  
Wild Type ◽  
Phosphotransferase System ◽  
Gene Transcripts ◽  
Bacterial Phosphotransferase System

ABSTRACT HPr, the phosphocarrier protein of the bacterial phosphotransferase system, mediates catabolite repression of a number of operons in gram-positive bacteria. In order to participate in the regulatory process, HPr is activated by phosphorylation of a conserved serine-46 residue. To study the potential role of HPr in the regulation of Cry4A protoxin synthesis in Bacillus thuringiensis subsp. israelensis, we produced a catabolite repression-negative mutant by replacing the wild-type copy of the ptsH gene with a mutated copy in which the conserved serine residue of HPr was replaced with an alanine. HPr isolated from the mutant strain was not phosphorylated at Ser-45 by HPr kinase, but phosphorylation at His-14 was found to occur normally. The enzyme I and HPr kinase activities of the mutant were not affected. Analysis of the B. thuringiensis subsp. israelensis mutant harboring ptsH-S45A in the chromosome showed that cry4A expression was derepressed from the inhibitory effect of glucose. The mutant strain produced both cry4A and σ35 gene transcripts 4 h ahead of the parent strain, but there was no effect on σ28 synthesis. In wild-type B. thuringiensis subsp. israelensis cells, cry4A mRNA was observed from 12 h onwards, while in the mutant it appeared at 8 h and was produced for a longer period. The total amount of cry4A transcripts produced by the mutant was higher than by the parent strain. There was a 60 to 70% reduction in the sporulation efficiency of the mutant B. thuringiensis subsp. israelensis strain compared to the wild-type strain.

scholarly journals Impact of theglpQ2Gene on Virulence in a Streptococcus pneumoniae Serotype 19A Sequence Type 320 Strain

2014 ◽  
Vol 83 (2) ◽  
pp. 682-692 ◽  
Author(s):  
Yi-Ping Chuang ◽  
Zih-Rong Peng ◽  
Shun-Fu Tseng ◽  
Yu-Chun Lin ◽  
Huey-Kang Sytwu ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Parent Strain ◽  
Severe Pneumonia ◽  
Exponential Phase ◽  
Sequence Type ◽  
Infection Model ◽  
Respiratory Pathogens ◽  
Content Type ◽  
Human Lung Epithelial Cell ◽  
Lung Colonization

Glycerophosphodiester phosphodiesterase (GlpQ) metabolizes glycerophosphorylcholine from the lung epithelium to produce free choline, which is transformed into phosphorylcholine and presented on the surfaces of many respiratory pathogens. Two orthologs ofglpQgenes are found inStreptococcus pneumoniae:glpQ, with a membrane motif, is widespread in pneumococci, whereasglpQ2, which shares high similarity withglpQinHaemophilus influenzaeandMycoplasma pneumoniae, is present only inS. pneumoniaeserotype 3, 6B, 19A, and 19F strains. Recently, serotype 19A has emerged as an epidemiological etiology associated with invasive pneumococcal diseases. Thus, we investigated the pathophysiological role ofglpQ2in a serotype 19A sequence type 320 (19AST320) strain, which was the prevalent sequence type in 19A associated with severe pneumonia and invasive pneumococcal disease in pediatric patients. Mutations inglpQ2reduced phosphorylcholine expression and the anchorage of choline-binding proteins to the pneumococcal surface during the exponential phase, where the mutants exhibited reduced autolysis and lower natural transformation abilities than the parent strain. The deletion ofglpQ2also decreased the adherence and cytotoxicity to human lung epithelial cell lines, whereas these functions were indistinguishable from those of the wild type in complementation strains. In a murine respiratory tract infection model,glpQ2was important for nasopharynx and lung colonization. Furthermore, infection with aglpQ2mutant decreased the severity of pneumonia compared with the parent strain, andglpQ2gene complementation restored the inflammation level. Therefore,glpQ2enhances surface phosphorylcholine expression inS. pneumoniae19AST320 during the exponential phase, which contributes to the severity of pneumonia by promoting adherence and host cell cytotoxicity.

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