scholarly journals Antibodies to Capsular Polysaccharide and Clumping Factor A Prevent Mastitis and the Emergence of Unencapsulated and Small-Colony Variants of Staphylococcus aureus in Mice

2008 ◽  
Vol 76 (12) ◽  
pp. 5738-5744 ◽  
Author(s):  
Lorena P. N. Tuchscherr ◽  
Fernanda R. Buzzola ◽  
Lucía P. Alvarez ◽  
Jean C. Lee ◽  
Daniel O. Sordelli
Keyword(s):  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
Passive Immunization ◽  
Mammary Glands ◽  
Specific Antiserum ◽  
Effective Vaccine ◽  
Small Colony Variants ◽  
Serotype 5 ◽  
Small Colony

ABSTRACT The pathogenesis of Staphylococcus aureus infections is influenced by multiple virulence factors that are expressed under variable conditions, and this has complicated the design of an effective vaccine. Clinical trials that targeted the capsule or clumping factor A (ClfA) failed to protect the recipients against staphylococcal infections. We passively immunized lactating mice with rabbit antibodies to S. aureus capsular polysaccharide (CP) serotype 5 (CP5) or CP8 or with monoclonal antibodies to ClfA. Mice immunized with antibodies to CP5 or CP8 or with ClfA had significantly reduced tissue bacterial burdens 4 days after intramammary challenge with encapsulated S. aureus strains. After several passages in mice passively immunized with CP-specific antiserum, increasing numbers of stable unencapsulated variants of S. aureus were cultured from the infected mammary glands. Greater numbers of these unencapsulated S. aureus variants than of the corresponding encapsulated parental strains were internalized in vitro in MAC-T bovine cells. Furthermore, small-colony variants (SCVs) were recovered from the infected mammary glands after several passages in mice passively immunized with CP-specific antiserum. A combination of antibodies effectively sterilized mammary glands in a significant number of passively immunized mice. More importantly, passive immunization with antibodies to both CP and ClfA fully inhibited the emergence of unencapsulated “escape mutants” and significantly reduced the appearance of SCVs. A vaccine formulation comprising CP conjugates plus a surface-associated protein adhesin may be more effective than either antigen alone for prevention of S. aureus infections.

scholarly journals Antibodies to Staphylococcus aureus Serotype 8 Capsular Polysaccharide React with and Protect against Serotype 5 and 8 Isolates

2014 ◽  
Vol 82 (12) ◽  
pp. 5049-5055 ◽  
Author(s):  
Saeyoung Park ◽  
Sabina Gerber ◽  
Jean C. Lee
Keyword(s):  
Staphylococcus Aureus ◽  
Conjugate Vaccine ◽  
Rational Design ◽  
Capsular Polysaccharide ◽  
Passive Immunization ◽  
Reactive Material ◽  
Content Type ◽  
Serotype 5 ◽  
Opsonophagocytic Killing

ABSTRACTMostStaphylococcus aureusisolates produce either a serotype 5 (CP5) or 8 (CP8) capsular polysaccharide, and the CP antigens are targets for vaccine development. Since CP5 and CP8 have similar trisaccharide repeating units, it is important to identify an epitope shared by both CP5 and CP8. To characterize cross-reactivity between CP5 and CP8, the immunogenicity of CP5 and CP8 conjugate vaccines in mice and rabbits was evaluated by serological assays. Immune sera were also tested for functional activity byin vitroopsonophagocytic-killing assays and a murine bacteremia model. Antibodies to the CP5-cross-reactive material 197 (CRM197) conjugate vaccine bound only to purified CP5. In contrast, antibodies to the CP8-CRM conjugate vaccine reacted with CP8 and (to a lesser extent) CP5. De-O-acetylation of CP5 increased its reactivity with CP8 antibodies. Moreover, CP8 antibodies bound toPseudomonas aeruginosaO11 lipopolysaccharide, which has a trisaccharide repeating unit similar to that of theS. aureusCPs. CP8-CRM antibodies mediatedin vitroopsonophagocytic killing ofS. aureusexpressing CP5 or CP8, whereas CP5-CRM antibodies were serotype specific. Passive immunization with antiserum to CP5-CRM or CP8-CRM protected mice against bacteremia induced by a serotype 5S. aureusisolate, suggesting that CP8-CRM elicits antibodies cross-reactive to CP5. The identification of epitopes shared by CP5 and CP8 may inform the rational design of a vaccine to protect against infections caused by CP5- or CP8-producing strains ofS. aureus.

scholarly journals Antibiotic activity against small-colony variants of Staphylococcus aureus: review of in vitro, animal and clinical data

2013 ◽  
Vol 68 (7) ◽  
pp. 1455-1464 ◽  
Author(s):  
Laetitia G. Garcia ◽  
Sandrine Lemaire ◽  
Barbara C. Kahl ◽  
Karsten Becker ◽  
Richard A. Proctor ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Clinical Data ◽  
Antibiotic Activity ◽  
Small Colony Variants ◽  
Small Colony

scholarly journals Joint antibiotic and phage therapy: addressing the limitations of a seemingly ideal phage for treating Staphylococcus aureus infections

2020 ◽  
Author(s):  
Brandon A. Berryhill ◽  
Douglas L. Huseby ◽  
Ingrid C. McCall ◽  
Diarmaid Hughes ◽  
Bruce R. Levin
Keyword(s):  
Staphylococcus Aureus ◽  
Bacterial Infections ◽  
Phage Therapy ◽  
Receptor Site ◽  
Clinical Isolates ◽  
Broad Host Range ◽  
Antibiotic Resistant ◽  
Small Colony Variants ◽  
Small Colony

AbstractIn response to increasing frequencies of antibiotic-resistant pathogens, there has been a resurrection of interest in the use of bacteriophage to treat bacterial infections: phage therapy. Here we explore the potential of a seemingly ideal phage, PYOSa, for combination phage and antibiotic treatment of Staphylococcus aureus infections. (i) This K-like phage has a broad host range; all 83 tested clinical isolates of S.aureus tested were susceptible to PYOSa. (ii) Because of the mode of action of PYOSaS. aureus is unlikely to generate classical receptor-site mutants resistant to PYOSa; none were observed in the 13 clinical isolates tested. (iii) PYOSa kills S. aureus at high rates. On the downside, the results of our experiments and tests of the joint action of PYOSa and antibiotics raise issues that must be addressed before PYOSa is employed clinically. Despite the maintenance of the phage, PYOSa does not clear the populations of S. aureus. Due to the ascent of a phenotypically diverse array of small colony variants following an initial demise, the bacterial populations return to densities similar to that of phage-free controls. Using a combination of mathematical modeling and in vitro experiments, we postulate and present evidence for a mechanism to account for the demise–resurrection dynamics of PYOSa and S. aureus. Critically for phage therapy, our experimental results suggest that treatment with PYOSa followed by bactericidal antibiotics can clear populations of S. aureus more effectively than the antibiotics alone.Significance StatementThe increasing frequency of antibiotic-resistant pathogens has fostered a quest for alternative means to treat bacterial infections. Prominent in this quest is a therapy that predates antibiotics: bacteriophage. This study explores the potential of a phage, PYOSa, for treating Staphylococcus aureus infections in combination with antibiotics. On first consideration, this phage, isolated from a commercial therapeutic cocktail, seems ideal for this purpose. The results of this population dynamic and genomic analysis study identify a potential liability of using PYOSa for therapy. Due to the production of potentially pathogenic atypical small colony variants, PYOSa alone cannot eliminate S. aureus populations. However, we demonstrate that by following the administration of PYOSa with bactericidal antibiotics, this limitation and potential liability can be addressed.

scholarly journals Comparative Opsonic and Protective Activities of Staphylococcus aureus Conjugate Vaccines Containing Native or Deacetylated Staphylococcal Poly-N-Acetyl-β-(1-6)-Glucosamine

2005 ◽  
Vol 73 (10) ◽  
pp. 6752-6762 ◽  
Author(s):  
Tomás Maira-Litrán ◽  
Andrea Kropec ◽  
Donald A. Goldmann ◽  
Gerald B. Pier
Keyword(s):  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
Lethal Dose ◽  
Passive Immunization ◽  
Conjugate Vaccines ◽  
Specific Antibodies ◽  
Dose Dependent Fashion ◽  
Protective Antibodies ◽  
High Level

ABSTRACT Staphylococcus aureus and Staphylococcus epidermidis both synthesize the surface polysaccharide poly-N-acetyl-β-(1-6)-glucosamine (PNAG), which is produced in vitro with a high level (>90%) of the amino groups substituted by acetate. Here, we examined the role of the acetate substituents of PNAG in generating opsonic and protective antibodies. PNAG and a deacetylated form of the antigen (dPNAG; 15% acetylation) were conjugated to the carrier protein diphtheria toxoid (DT) and used to immunize animals. Mice responded in a dose-dependent fashion to both conjugate vaccines, with maximum antibody titers observed at the highest dose and 4 weeks after the last of three weekly immunizations. PNAG-DT and dPNAG-DT vaccines were also very immunogenic in rabbits. Antibodies raised to the conjugate vaccines in rabbits mediated the opsonic killing of various staphylococcal strains, but the specificity of the opsonic killing was primarily to dPNAG, as this antigen inhibited the killing of S. aureus strains by both PNAG- and dPNAG-specific antibodies. Passive immunization of mice with anti-dPNAG-DT rabbit sera showed significant levels of clearance of S. aureus from the blood (54 to 91%) compared to control mice immunized with normal rabbit sera, whereas PNAG-specific antibodies were ineffective at clearing S. aureus. Passive immunization of mice with a goat antiserum raised to the dPNAG-DT vaccine protected against a lethal dose of three different S. aureus strains. Overall, these data show that immunization of animals with a conjugate vaccine of dPNAG elicit antibodies that mediated opsonic killing and protected against S. aureus infection, including capsular polysaccharide types 5 and 8 and an untypable strain.

scholarly journals Staphylococcus aureus Strains That Express Serotype 5 or Serotype 8 Capsular Polysaccharides Differ in Virulence

2005 ◽  
Vol 73 (6) ◽  
pp. 3502-3511 ◽  
Author(s):  
Andrew Watts ◽  
Danbing Ke ◽  
Qun Wang ◽  
Anil Pillay ◽  
Anne Nicholson-Weller ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
Biological Properties ◽  
Human Neutrophils ◽  
Mixed Inoculum ◽  
Serotype 5 ◽  
Biochemical Analyses ◽  
Isogenic Mutants

ABSTRACT Most isolates of Staphylococcus aureus produce a serotype 5 (CP5) or 8 (CP8) capsular polysaccharide. To investigate whether CP5 and CP8 differ in their biological properties, we created isogenic mutants of S. aureus Reynolds that expressed CP5, CP8, or no capsule. Biochemical analyses of CP5 and CP8 purified from the isogenic S. aureus strains were consistent with published structures. The degree of O acetylation of each polysaccharide was similar, but CP5 showed a greater degree of N acetylation. Mice challenged with the CP5+ strain showed a significantly higher bacteremia level than mice challenged with the CP8+ strain. Similarly, the CP5+ strain survived preferentially in the bloodstream and kidneys of infected mice challenged with a mixed inoculum containing both strains. The enhanced virulence of the CP5+ strain in vivo correlated with its greater resistance to in vitro killing in whole mouse blood. Likewise, in vitro opsonophagocytic killing assays with human neutrophils and sera revealed greater survival of the Reynolds (CP5) strain, even though the kinetics of opsonization by C3b and iC3b was similar for both the CP5+ and CP8+ strains. Electron micrographs demonstrated C3 molecules on the cell wall beneath the capsule layer for both serotype 5 and 8 strains. Purified CP5 and CP8 stimulated a modest oxidative burst in human neutrophils but failed to activate the alternative complement pathway. These results indicate that CP5 and CP8 differ in a number of biological properties, and these differences likely contribute to the relative virulence of serotype 5 and 8 S. aureus in vivo.

scholarly journals Role of persisters and small-colony variants in antibiotic resistance of planktonic and biofilm-associated Staphylococcus aureus: an in vitro study

2009 ◽  
Vol 58 (8) ◽  
pp. 1067-1073 ◽  
Author(s):  
Rachna Singh ◽  
Pallab Ray ◽  
Anindita Das ◽  
Meera Sharma
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Wild Type ◽  
Planktonic Cells ◽  
Intrinsic Resistance ◽  
Persister Cells ◽  
Small Colony Variants ◽  
Small Colony ◽  
Wild Type Parent

The presence of persister cells and small-colony variants (SCVs) has been associated with enhanced antibiotic resistance of many organisms in biofilms. This study investigated whether persisters and/or SCVs contribute to the antibiotic resistance of Staphylococcus aureus biofilms. A detailed dose-dependent killing of biofilms and planktonic cells with five antibiotics (oxacillin, cefotaxime, amikacin, ciprofloxacin and vancomycin) was analysed by treating them with each antibiotic at a concentration of 0–100 μg ml−1 at 37 °C for 48 h. The killing of biofilm cells by all of the antibiotics showed the presence of persister cells – most cells in the population died, leaving a fraction that persisted, even at higher concentrations of the antibiotics. These persisters represented a transient resistant phenotype and reverted to a killing curve resembling that of the wild-type parent upon re-exposure to the antibiotics. SCVs were observed in biofilms only after treatment with ciprofloxacin, and these SCVs were of a transient nature. The treatment of planktonic cells with oxacillin, cefotaxime, ciprofloxacin and vancomycin killed the entire population and no persisters were detected. Transient SCVs, observed in planktonic cells following exposure to these antibiotics, were killed at higher antibiotic concentrations. The treatment of planktonic cells with amikacin yielded a small subpopulation of survivors that included persisters (at numbers significantly lower than for the biofilms) and highly resistant, stable SCVs with an increased biofilm-forming capacity in comparison with the wild-type parent. Thus the high resistance of S. aureus biofilms to multiple unrelated antibiotics is largely dependent on the presence of persister cells. Biofilms harbour a large number of persisters in comparison with planktonic cultures, which either do not harbour persisters or harbour only a small number. SCVs, although not specifically associated with S. aureus biofilms, have an increased biofilm-forming capacity and this may explain the frequent isolation of SCVs from biofilm-associated infections. The intrinsic resistance of these variants may in turn contribute to the enhanced antibiotic resistance of the biofilms thus formed.

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