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 In vitro Efficacy of Arbekacin and Sulbactam/Ampicillin in Combination to Inhibit Occurrence of Staphylococcus aureus Small Colony Variants

2010 ◽  
Vol 56 (4) ◽  
pp. 339-349
Author(s):  
EIJI TOMINAGA ◽  
TERUYO ITO ◽  
VON EIFF CHRISTOF ◽  
KEIICHI HIRAMATSU
Keyword(s):  
Staphylococcus Aureus ◽  
Small Colony Variants ◽  
Small Colony

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.

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 Thymidine-Dependent Staphylococcus aureus Small-Colony Variants Are Induced by Trimethoprim-Sulfamethoxazole (SXT) and Have Increased Fitness during SXT Challenge

2015 ◽  
Vol 59 (12) ◽  
pp. 7265-7272 ◽  
Author(s):  
Andre Kriegeskorte ◽  
Nicola Ivan Lorè ◽  
Alessandra Bragonzi ◽  
Camilla Riva ◽  
Marco Kelkenberg ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Short Term ◽  
Small Colony Variants ◽  
Content Type ◽  
Short Term Exposure ◽  
Small Colony ◽  
Selection Of

ABSTRACTTrimethoprim-sulfamethoxazole (SXT) is a possible alternative for the treatment of community- and hospital-acquired methicillin-resistantStaphylococcus aureus(MRSA) due to the susceptibility of most MRSA strains to the drug. However, after long-term treatment with SXT, thymidine-dependent (TD) SXT-resistant small-colony variants (SCVs) emerge. In TD-SCVs, mutations of thymidylate synthase ([TS]thyA) occur. Until now, it has never been systematically investigated that SXT is triggering the induction and/or selection of TD-SCVs. In our study, we performed induction, reversion, and competition experimentsin vitroandin vivousing a chronic mouse pneumonia model to determine the impact of SXT on the emergence of TD-SCVs. SCVs were characterized by light and transmission electron microscopy (TEM) and auxotrophism testing. Short-term exposure ofS. aureusto SXT induced the TD-SCV phenotype inS. aureusSH1000, while selection of TD-SCVs withthyAmutations occurred after long-term exposure. In reversion experiments with clinical and laboratory TD-SCVs, all revertants carried compensating mutations at the initially identified mutation site. Competition experimentsin vitroandin vivorevealed a survival and growth advantage of the ΔthyAmutant under low-thymidine availability and SXT exposure although this advantage was less profoundin vivo. Our results show that SXT induces the TD-SCV phenotype after short-term exposure, while long-term exposure selects forthyAmutations, which provide an advantage for TD-SCVs under specified conditions. Thus, our results further an understanding of the dynamic processes occurring during SXT exposure with induction and selection ofS. aureusTD-SCVs.

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