Characterization of the Importance of Polysaccharide Intercellular Adhesin/Hemagglutinin of Staphylococcus epidermidis in the Pathogenesis of Biomaterial-Based Infection in a Mouse Foreign Body Infection Model

ABSTRACT The production of biofilm is thought to be crucial in the pathogenesis of prosthetic-device infections caused byStaphylococcus epidermidis. An experimental animal model was used to assess the importance of biofilm production, which is mediated by polysaccharide intercellular adhesin/hemagglutinin (PIA/HA), in the pathogenesis of a biomaterial-based infection. Mice were inoculated along the length of a subcutaneously implanted intravenous catheter with either wild-type S. epidermidis1457 or its isogenic PIA/HA-negative mutant. The wild-type strain was significantly more likely to cause a subcutaneous abscess than the mutant strain (P < 0.01) and was significantly less likely to be eradicated from the inoculation site by host defense (P < 0.05). In addition, the wild-type strain was found to adhere to the implanted catheters more abundantly than the PIA/HA-negative mutant (P < 0.05). The reliability of the adherence assay was assessed by scanning electron microscopy. To exclude contamination or spontaneous infection, bacterial strains recovered from the experimental animals were compared to inoculation strains by analysis of restriction fragment length polymorphism patterns by pulsed-field gel electrophoresis. In vitro binding of the wild-type strain and its isogenic mutant to a fibronectin-coated surface was similar. These results confirm the importance of biofilm production, mediated by PIA/HA, in the pathogenesis of S. epidermidis experimental foreign body infection.

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Characterization of Staphylococcus epidermidisPolysaccharide Intercellular Adhesin/Hemagglutinin in the Pathogenesis of Intravascular Catheter-Associated Infection in a Rat Model

Infection and Immunity ◽

10.1128/iai.67.5.2656-2659.1999 ◽

1999 ◽

Vol 67 (5) ◽

pp. 2656-2659 ◽

Cited By ~ 169

Author(s):

Mark E. Rupp ◽

Joseph S. Ulphani ◽

Paul D. Fey ◽

Dietrich Mack

Keyword(s):

Central Venous Catheter ◽

Staphylococcus Epidermidis ◽

Venous Catheter ◽

Infection Model ◽

Polysaccharide Intercellular Adhesin ◽

Intravascular Catheter ◽

Central Venous ◽

Biofilm Production ◽

Negative Mutant

ABSTRACT Biofilm production is thought to be a crucial factor in the ability of Staphylococcus epidermidis to produce a biomaterial-based infection. A rat central venous catheter (CVC)-associated infection model was used to assess the importance of biofilm production, mediated by polysaccharide intercellular adhesin/hemagglutinin (PIA/HA), in the pathogenesis of intravascular catheter-associated infection. PIA/HA-positive S. epidermidis 1457 was significantly more likely to cause a CVC-associated infection (71 versus 14%, P < 0.03) resulting in bacteremia and metastatic disease than its isogenic PIA/HA-negative mutant. These results confirm the importance of biofilm production, mediated by PIA/HA, in the pathogenesis of S. epidermidis experimental CVC-associated infection.

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The Abilities of a Staphylococcus epidermidis Wild-Type Strain and Its Slime-Negative Mutant To Induce Endocarditis in Rabbits Are Comparable

Infection and Immunity ◽

10.1128/iai.66.6.2778-2781.1998 ◽

1998 ◽

Vol 66 (6) ◽

pp. 2778-2781 ◽

Cited By ~ 23

Author(s):

Francoise Perdreau-Remington ◽

Merle A. Sande ◽

Georg Peters ◽

Henry F. Chambers

Keyword(s):

Staphylococcus Epidermidis ◽

Parent Strain ◽

Type Strain ◽

Wild Type Strain ◽

Rabbit Model ◽

Inoculum Size ◽

Wild Type ◽

Negative Mutant

ABSTRACT The abilities of a parent and mutant pair of Staphylococcus epidermidis strains, the slime-producing parent RP62A and its slime-negative mutant, to establish endocarditis in a rabbit model of aortic valve endocarditis and to accumulate and adhere to surfaces in vitro were compared. Vegetation titer and infection rate depended on the presence or absence of a catheter (P = 0.020) and on inoculum size (P < 0.001) but not on the infecting strain. The ability of the parent strain vis-à-vis its mutant to accumulate in vitro on surfaces as demonstrated in a slime test did not correlate with any enhancement in the development of endocarditis in the rabbit model. In vitro initial adherence rates were identical. Both isolates accumulated to the same reduced extent in vitro in the presence of serum, albumin, or gelatin. Adhesion was equally promoted by addition of fibronectin. These data suggest that the in vitro phenomenon of accumulation described as slime production in the absence of serum may not be an important virulence determinant in vivo.

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In VivoEfficacy of Human Simulated Regimens of Carbapenems and Comparator Agents against NDM-1-Producing Enterobacteriaceae

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01946-13 ◽

2013 ◽

Vol 58 (3) ◽

pp. 1671-1677 ◽

Cited By ~ 23

Author(s):

Dora E. Wiskirchen ◽

Patrice Nordmann ◽

Jared L. Crandon ◽

David P. Nicolau

Keyword(s):

Type Strain ◽

Wild Type Strain ◽

Similar Efficacy ◽

Infection Model ◽

High Dose ◽

Wild Type ◽

Prolonged Infusion ◽

Content Type

ABSTRACTDoripenem and ertapenem have demonstrated efficacy against several NDM-1-producing isolatesin vivo, despite having high MICs. In this study, we sought to further characterize the efficacy profiles of humanized regimens of standard (500 mg given every 8 h) and high-dose, prolonged infusion of doripenem (2 g given every 8 h, 4-h infusion) and 1 g of ertapenem given intravenously every 24 h and the comparator regimens of ceftazidime at 2 g given every 8 h (2-h infusion), levofloxacin at 500 mg every 24 h, and aztreonam at 2 g every 6 h (1-h infusion) against a wider range of isolates in a murine thigh infection model. An isogenic wild-type strain and NDM-1-producingKlebsiella pneumoniaeand eight clinical NDM-1-producing members of the familyEnterobacteriaceaewere tested in immunocompetent- and neutropenic-mouse models. The wild-type strain was susceptible to all of the agents, while the isogenic NDM-1-producing strain was resistant to ceftazidime, doripenem, and ertapenem. Clinical NDM-1-producing strains were resistant to nearly all five of the agents (two were susceptible to levofloxacin). In immunocompetent mice, all of the agents produced ≥1-log10CFU reductions of the isogenic wild-type and NDM-1-producing strains after 24 h. Minimal efficacy of ceftazidime, aztreonam, and levofloxacin against the clinical NDM-1-producing strains was observed. However, despitein vitroresistance, ≥1-log10CFU reductions of six of eight clinical strains were achieved with high-dose, prolonged infusion of doripenem and ertapenem. Slight enhancements of doripenem activity over the standard doses were obtained with high-dose, prolonged infusion for three of the four isolates tested. Similar efficacy observations were noted in neutropenic mice. These data suggest that carbapenems are a viable treatment option for infections caused by NDM-1-producingEnterobacteriaceae.

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Conversion of Staphylococcus epidermidis Strains from Commensal to Invasive by Expression of the ica Locus Encoding Production of Biofilm Exopolysaccharide

Infection and Immunity ◽

10.1128/iai.73.5.3188-3191.2005 ◽

2005 ◽

Vol 73 (5) ◽

pp. 3188-3191 ◽

Cited By ~ 65

Author(s):

Hualin Li ◽

Lin Xu ◽

Jianping Wang ◽

Yumei Wen ◽

Cuong Vuong ◽

...

Keyword(s):

Central Venous Catheter ◽

Staphylococcus Epidermidis ◽

Biofilm Formation ◽

Venous Catheter ◽

Infection Model ◽

Polysaccharide Intercellular Adhesin ◽

Central Venous ◽

Biofilm Production ◽

Central Venous Catheter Infection

ABSTRACT To test if biofilm formation in Staphylococcus epidermidis is dependent on the polysaccharide intercellular adhesin, whose biosynthesis is driven by the ica locus, a plasmid containing the ica locus was transferred to three ica-negative strains. Using in vitro biofilm assays and a rat central venous catheter infection model, we confirmed the importance of the ica locus for biofilm production and pathogenesis of S. epidermidis.

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Pertussis Toxin and Adenylate Cyclase Toxin Provide a One-Two Punch for Establishment of Bordetella pertussis Infection of the Respiratory Tract

Infection and Immunity ◽

10.1128/iai.73.5.2698-2703.2005 ◽

2005 ◽

Vol 73 (5) ◽

pp. 2698-2703 ◽

Cited By ~ 64

Author(s):

Nicholas H. Carbonetti ◽

Galina V. Artamonova ◽

Charlotte Andreasen ◽

Nicholas Bushar

Keyword(s):

Adenylate Cyclase ◽

Respiratory Tract ◽

Pertussis Toxin ◽

Bordetella Pertussis ◽

Type Strain ◽

Wild Type Strain ◽

Infection Model ◽

Wild Type ◽

Adenylate Cyclase Toxin ◽

Tract Infections

ABSTRACT Previously we found that pertussis toxin (PT), an exotoxin virulence factor produced by Bordetella pertussis, plays an important early role in colonization of the respiratory tract by this pathogen, using a mouse intranasal infection model. In this study, we examined the early role played by another exotoxin produced by this pathogen, adenylate cyclase toxin (ACT). By comparing a wild-type strain to a mutant strain (ΔCYA) with an in-frame deletion of the cyaA gene encoding ACT, we found that the lack of ACT confers a significant peak (day 7) colonization defect (1 to 2 log10). In mixed-infection experiments, the ΔCYA strain was significantly outcompeted by the wild-type strain, and intranasal administration of purified ACT did not increase colonization by ΔCYA. These data suggest that ACT benefits the bacterial cells that produce it and, unlike PT, does not act as a soluble factor benefiting the entire infecting bacterial population. Comparison of lower respiratory tract infections over the first 4 days after inoculation revealed that the colonization defect of the PT deletion strain was apparent earlier than that of ΔCYA, suggesting that PT plays an earlier role than ACT in the establishment of B. pertussis infection. Examination of cells in the bronchoalveolar lavage fluid of infected mice revealed that, unlike PT, ACT does not appear to inhibit neutrophil influx to the respiratory tract early after infection but may combat neutrophil activity once influx has occurred.

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Leptospira interrogans lpxDHomologue Is Required for Thermal Acclimatization and Virulence

Infection and Immunity ◽

10.1128/iai.00897-15 ◽

2015 ◽

Vol 83 (11) ◽

pp. 4314-4321 ◽

Cited By ~ 13

Author(s):

Azad Eshghi ◽

Jeremy Henderson ◽

M. Stephen Trent ◽

Mathieu Picardeau

Keyword(s):

Outer Membrane ◽

Type Strain ◽

Lipid A ◽

Wild Type Strain ◽

Infection Model ◽

Leptospira Interrogans ◽

Wild Type ◽

Content Type ◽

Physiological Temperature ◽

Animal Infection

ABSTRACTLeptospirosis is an emerging disease with an annual occurrence of over 1 million human cases worldwide. PathogenicLeptospirabacteria are maintained in zoonotic cycles involving a diverse array of mammals, with the capacity to survive outside the host in aquatic environments. Survival in the diverse environments encountered byLeptospiralikely requires various adaptive mechanisms. Little is known aboutLeptospiraouter membrane modification systems, which may contribute to the capacity of these bacteria to successfully inhabit and colonize diverse environments and animal hosts.Leptospirabacteria carry two genes annotated as UDP-3-O-[3-hydroxymyristoyl] glucosamineN-acyltransferase genes (la0512 and la4326 [lpxD1andlpxD2]) that in other bacteria are involved in the early steps of biosynthesis of lipid A, the membrane lipid anchor of lipopolysaccharide. Inactivation of only one of these genes, la0512/lpxD1, imparted sensitivity to the host physiological temperature (37°C) and rendered the bacteria avirulent in an animal infection model. Polymyxin B sensitivity assays revealed compromised outer membrane integrity in thelpxD1mutant at host physiological temperature, but structural analysis of lipid A in the mutant revealed only minor changes in the lipid A moiety compared to that found in the wild-type strain. In accordance with this, anin transcomplementation restored the phenotypes to a level comparable to that of the wild-type strain. These results suggest that the gene annotated aslpxD1inLeptospira interrogansplays an important role in temperature adaptation and virulence in the animal infection model.

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Biofilm Formation, icaADBC Transcription, and Polysaccharide Intercellular Adhesin Synthesis by Staphylococci in a Device-Related Infection Model

Infection and Immunity ◽

10.1128/iai.73.3.1811-1819.2005 ◽

2005 ◽

Vol 73 (3) ◽

pp. 1811-1819 ◽

Cited By ~ 104

Author(s):

Ursula Fluckiger ◽

Martina Ulrich ◽

Andrea Steinhuber ◽

Gerd Döring ◽

Dietrich Mack ◽

...

Keyword(s):

Staphylococcus Epidermidis ◽

Biofilm Formation ◽

Anaerobic Growth ◽

Infection Model ◽

Transcript Analysis ◽

Polysaccharide Intercellular Adhesin ◽

Wild Type ◽

Type Strains

ABSTRACT Biofilm formation of Staphylococcus epidermidis and S. aureus is mediated by the polysaccharide intercellular adhesin (PIA) encoded by the ica operon. We used a device-related animal model to investigate biofilm formation, PIA expression (immunofluorescence), and ica transcription (quantitative transcript analysis) throughout the course of infection by using two prototypic S. aureus strains and one S. epidermidis strain as well as corresponding ica mutants. During infection, the ica mutants were growth attenuated when inoculated in competition with the corresponding wild-type strains but not when grown singly. A typical biofilm was observed at the late course of infection. Only in S. aureus RN6390, not in S. aureus Newman, were PIA and ica-specific transcripts detectable after anaerobic growth in vitro. However, both S. aureus strains were PIA positive in vivo by day 8 of infection. ica transcription preceded PIA expression and biofilm formation in vivo. In S. epidermidis, both PIA and ica expression levels were elevated compared to those in the S. aureus strains in vitro as well as in vivo and were detectable throughout the course of infection. In conclusion, in S. aureus, PIA expression is dependent on the genetic background of the strain as well as on strong inducing conditions, such as those dominating in vivo. In S. epidermidis, PIA expression is elevated and less vulnerable to environmental conditions.

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Quorum-Quenching Acylase Reduces the Virulence of Pseudomonas aeruginosa in a Caenorhabditis elegans Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00380-09 ◽

2009 ◽

Vol 53 (11) ◽

pp. 4891-4897 ◽

Cited By ~ 74

Author(s):

Evelina Papaioannou ◽

Mariana Wahjudi ◽

Pol Nadal-Jimenez ◽

Gudrun Koch ◽

Rita Setroikromo ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Caenorhabditis Elegans ◽

Type Strain ◽

Wild Type Strain ◽

Quorum Quenching ◽

Homoserine Lactone ◽

Infection Model ◽

Wild Type ◽

Strain Pao1

ABSTRACT The Pseudomonas aeruginosa PAO1 gene pvdQ encodes an acyl-homoserine lactone (AHL) acylase capable of degrading N-(3-oxododecanoyl)-l-homoserine lactone by cleaving the AHL amide. PvdQ has been proven to function as a quorum quencher in vitro in a number of phenotypic assays. To address the question of whether PvdQ also shows quorum-quenching properties in vivo, an infection model based on the nematode Caenorhabditis elegans was explored. In a fast-acting paralysis assay, strain PAO1(pMEpvdQ), which overproduces PvdQ, was shown to be less virulent than the wild-type strain. More than 75% of the nematodes exposed to PAO1(pMEpvdQ) survived and continued to grow when using this strain as a food source. Interestingly, in a slow-killing assay monitoring the survival of the nematodes throughout a 4-day course, strain PAO1-ΔpvdQ was shown to be more virulent than the wild-type strain, confirming the role of PvdQ as a virulence-reducing agent. It was observed that larval stage 1 (L1) to L3-stage larvae benefit much more from protection by PvdQ than L4 worms. Finally, purified PvdQ protein was added to C. elegans worms infected with wild-type PAO1, and this resulted in reduced pathogenicity and increased the life span of the nematodes. From our observations we can conclude that PvdQ might be a strong candidate for antibacterial therapy against Pseudomonas infections.

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The Role of graRS in Regulating Virulence and Antimicrobial Resistance in Methicillin-Resistant Staphylococcus aureus

Frontiers in Microbiology ◽

10.3389/fmicb.2021.727104 ◽

2021 ◽

Vol 12 ◽

Author(s):

Le Chen ◽

Zihui Wang ◽

Tao Xu ◽

Hongfei Ge ◽

Fangyue Zhou ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Type Strain ◽

Bacterial Resistance ◽

Wild Type Strain ◽

Lysine Biosynthesis ◽

Infection Model ◽

Wild Type ◽

Methicillin Resistant

Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of both community- and hospital-associated infections. The antibiotic resistance and virulence characteristics of MRSA are largely regulated by two-component signal transduction systems (TCS) including the graRS TCS. To make a relatively comprehensive insight into graRS TCS in MRSA, the bioinformatics analysis of dataset GSE26016 (a S. aureus HG001 WT strain vs. the ΔgraRS mutant) from Gene Expression Omnibus (GEO) database was performed, and a total of 563 differentially expressed genes (DEGs) were identified. GO analysis revealed that the DEGs were mainly enriched in the “de novo” IMP biosynthetic process, lysine biosynthetic process via diaminopimelate, and pathogenesis; and they were mainly enriched in purine metabolism, lysine biosynthesis, and monobactam biosynthesis in KEGG analysis. WGCNA suggested that the turquoise module was related to the blue module, and the genes in these two modules were associated with S. aureus virulence and infection. To investigate the role of graRS in bacterial virulence, a graRS knockout mutant (ΔgraRS) was constructed using MRSA USA500 2,395 strain as a parent strain. Compared to the wild-type strain, the USA500ΔgraRS showed reduced staphyloxanthin production, retarded coagulation, weaker hemolysis on blood agar plates, and a decreased biofilm formation. These altered phenotypes were restored by the complementation of a plasmid-expressed graRS. Meanwhile, an expression of the virulence-associated genes (coa, hla, hlb, agrA, and mgrA) was downregulated in the ΔgraRS mutant. Consistently, the A549 epithelial cells invasion of the ΔgraRS mutant was 4-fold lower than that of the USA500 wild-type strain. Moreover, on the Galleria mellonella infection model, the survival rate at day 5 post infection in the USA500ΔgraRS group (55%) was obviously higher than that in the USA500 group (20%), indicating graRS knockout leads to a decreased virulence in vivo. In addition, the deletion of the graRS in the MRSA USA500 strain resulted in its increased susceptibilities to ampicillin, oxacillin, vancomycin, and gentamicin. Our work suggests that the graRS TCS plays an important role in regulating S. aureus virulence in vitro and in vivo and modulate bacterial resistance to various antibiotics.

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Solubilization of potassium-bearing minerals by a wild-type strain of Bacillus edaphicus and its mutants and increased potassium uptake by wheat

Canadian Journal of Microbiology ◽

10.1139/w05-117 ◽

2006 ◽

Vol 52 (1) ◽

pp. 66-72 ◽

Cited By ~ 140

Author(s):

Xia Fang Sheng ◽

Lin Yan He

Keyword(s):

Organic Acids ◽

Type Strain ◽

Wild Type Strain ◽

Capsular Polysaccharide ◽

Active Agent ◽

Triticum Aestivum L ◽

Wild Type ◽

Bacterial Strains ◽

Potassium Nutrition ◽

Tartaric Acids

Two potassium (K)-bearing minerals, Nanjing feldspar and Suzhou illite, were used to investigate K mobilization by the wild-type strain NBT of Bacillus edaphicus, also labeled MPs+, selected for high activity in mobilizing potassium from minerals, and by four of its UV + LiCl mutants, MPs++, MPs+1, MPs+2, and MPs–. In liquid cultures, the five bacterial strains showed better growth on Suzhou illite than on Nanjing feldspar. Suzhou illite was the better potassium source for the growth of the wild type and the MPs++, MPs+1, and MPs+2 mutants. Solubilization of K from its sources by the wild-type NBT and the MPs++ mutant resulted mostly from the action of organic acids and capsular polysaccharides. Oxalic acid seemed to be a more active agent for the solubilization of Nanjing feldspar. Oxalic and tartaric acids were likely involved in the solubilization of Suzhou illite. The MPs– mutant did not produce any organic acid or capsular polysaccharide when grown on the above two K sources. In a pot experiment, wheat (Triticum aestivum L.) 'Yangmai-158' was grown in a yellow–brown soil that had low available K. After inoculation with bacterial strains, B. edaphicus NBT and its four mutants, MPs++, MPs+1, MPs+2, and MPs– (in separate tests), the root growth and shoot growth of wheat were significantly increased by B. edaphicus NBT and the mutants MPs++ and MPs+1. Bacterial inoculation also resulted in significantly higher N, P, and K contents of plant components. The bacteria were able to survive in the wheat rhizosphere soils after root inoculation.Key words: Bacillus edaphicus, potassium release, organic acids, potassium nutrition.

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