In-vitro and in-vivo selection of Staphylococcus aureus mutants resistant to ciprofloxacin

1995 ◽  
Vol 35 (1) ◽  
pp. 95-102 ◽  
Author(s):  
S. A. Doss ◽  
G. S. Tillotson ◽  
N. L. Barg ◽  
S. G. B. Amyes
Keyword(s):  
Staphylococcus Aureus ◽  
In Vivo Selection ◽  
Selection Of

scholarly journals In Vitro and in Vivo Selection of Potentially Probiotic Lactobacilli From Nocellara del Belice Table Olives

2018 ◽  
Vol 9 ◽  
Author(s):  
Barbara Guantario ◽  
Paola Zinno ◽  
Emily Schifano ◽  
Marianna Roselli ◽  
Giuditta Perozzi ◽  
...  
Keyword(s):  
Table Olives ◽  
In Vivo Selection ◽  
Probiotic Lactobacilli ◽  
Selection Of

In Vivo Selection of Mycophenolate Mofetil-Resistant T Cells for Adoptive Immunotherapy.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3008-3008
Author(s):  
James Edward Griffin ◽  
Ben Carpenter ◽  
Emma Nicholson ◽  
Shao-an Xue ◽  
Martin Pule ◽  
...  
Keyword(s):  
T Cells ◽  
Mycophenolate Mofetil ◽  
Gene Transfer ◽  
Cd8 T Cells ◽  
Adoptive Immunotherapy ◽  
Selective Enrichment ◽  
In Vivo Selection ◽  
Selection Of

Abstract Abstract 3008 In vivo selection of mycophenolate mofetil-resistant T cells for adoptive immunotherapy. Background Following allogeneic solid organ or hematopoietic stem cell transplantation, adoptive transfer of therapeutic T cells may be hindered by the requirement for immune suppressive drugs to prevent rejection or graft-versus-host disease. Mycophenolate mofetil (MMF) is a non-competitive inhibitor of inosine-5'-monophosphate dehydrogenase 2 (IMPDH2), an inducible enzyme that generate guanine nucleotides for DNA and RNA synthesis in T cells. In this study, we have evaluated the potential for gene transfer to T cells of a mutated IMPDH2 that confers >2000-fold resistance to MMF (IMPDH2R; T333I, S351Y). Methods Wild type IMPDH2WT, IMPDH2R and IMPDH2 with a catalytic site mutation (IMPDH2CS; C331A) were cloned into SFG retroviral vectors as fusions to eGFP reporter sequences. Murine thymoma (BW 5147) or CD8 T cells were transduced with each vector and their phenotype and function evaluated in the presence or absence of mycophenolic acid (MPA), the active metabolite of MMF. Results BW thymoma cells transduced with IMPDH2R exhibited less apoptosis than cells transduced with IMPDH2CS in response to MPA (ratio % Annexin V+ MPA: no MPA- IMPDH2R = 1.2; IMPDH2CS = 2.9, p=0.01). Cells transduced with IMPDH2R were also able to overcome the G1 cell-cycle arrest induced by MPA when compared to control IMPDH2CS cells (Ratio %cells in S-G2/M phases MPA: no MPA- IMPDH2R = 1.0; IMPDH2CS = 0.3, p=0.03). This led to selective enrichment of IMPDH2R transduced cells in the presence of MPA. At low dose MPA (450nM), IMPDH2R transduced cells enriched compared to IMPDH2CS but not IMPDH2WT (ratio % GFP MPA: no MPA- IMPDH2R = 1.6 vs IMPDH2CS = 1.1, p=0.04 and IMPDH2WT = 1.5 p= 0.14). However, at high dose (4500nM) IMPDH2R exhibited enhanced enrichment (ratio % GFP MPA: no MPA- IMPDH2R = 2.8 vs IMPDH2CS = 1.0 p=0.03 and vs IMPDH2WT= 1.5 p=0.03). Gene transfer of IMPDH2R into murine CD8 T cells also led to selective enrichment compared to controls in the presence of MPA when cultured with proliferation-inducing common gamma-chain cytokines (ratio MPA: no MPA IMPDH2R = 4.4 vs. IMPDH2CS = 1.10, p=0.02). Strong selection for IMPDH2R-tranduced CD8 OT-1 T cells in the presence of MPA was also observed under conditions of antigen-induced proliferation (ratio IMPDH2R= 7.1, control = 0.8, p=0.002). To assess in vivo selection, sub-lethally irradiated (2Gy) B6.PL (Thy1.1) mice were injected with a 1:1 mix of OT1 TCR transgenic Thy1.2 CD8 T cells transduced with IMPDH2R or IMPDH2CS that could be differentiated by the congenic markers CD45.1 and CD45.2. Transferred cells were stimulated by s.c. injection with cognate peptide (SIINFEKL) in IFA and MMF (200mg/kg/day) was given by daily ip injection. As in vitro, IMPDH2R-transduced OT1 cells were preferentially selected over IMPDH2CS-transduced cells following MMF treatment (day 14 ratio IMPDH2R to IMPDHCSwas 19.3 vs 1.2 in the absence of MMF). Conclusions T cells transduced with IMPDH2R are resistant to the anti-proliferative and apoptotic effects of MPA in vitro and demonstrate strong selection in vivo compared to controls at therapeutic levels of MMF. These data support the potential of conferring MMF resistance as a strategy to permit the survival of therapeutic T cells in immunosuppressed allograft recipients. Disclosures: Stauss: Cell Medica: Scientific Advisor Other.

scholarly journals β-Lactams Increase the Antibacterial Activity of Daptomycin against Clinical Methicillin-Resistant Staphylococcus aureus Strains and Prevent Selection of Daptomycin-Resistant Derivatives

2012 ◽  
Vol 56 (12) ◽  
pp. 6192-6200 ◽  
Author(s):  
Shrenik Mehta ◽  
Christopher Singh ◽  
Konrad B. Plata ◽  
Palas K. Chanda ◽  
Arundhati Paul ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mutant Selection ◽  
Methicillin Resistant ◽  
Content Type ◽  
Oxacillin Resistance ◽  
Worm Model ◽  
Mrsa Strains ◽  
Selection Of

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) has emerged to be one of the most important pathogens both in health care and in community-onset infections. Daptomycin (DAP) is a cyclic anionic lipopeptide recommended for treatment of skin infections, bacteremia, and right-sided endocarditis caused by MRSA. Resistance to DAP (DAPr) has been reported in MRSA and is mostly accompanied by a parallel decrease in oxacillin resistance, a process known as the “seesaw effect.” Our study provides evidence that the seesaw effect applies to other β-lactams and carbapenems of clinical use, including nafcillin (NAF), cefotaxime (CTX), amoxicillin-clavulanic (AMC), and imipenem (IMP), in heterogeneous DAPrMRSA strains but not in MRSA strains expressing homogeneous β-lactam resistance. The antibacterial efficacy of DAP in combination with β-lactams was evaluated in isogenic DAP-susceptible (DAPs)/DaprMRSA strains originally obtained from patients that failed DAP monotherapy. Bothin vitro(MIC, synergy-kill curve) andin vivo(wax worm model) approaches were used. In these models, DAP and a β-lactam proved to be highly synergistic against both heterogeneous and homogeneous clinical DAPrMRSA strains. Mechanistically, β-lactams induced a reduction in the cell net positive surface charge, reverting the increased repulsion provoked by DAP alone, an effect that may favor the binding of DAP to the cell surface. The ease ofin vitromutant selection was observed when DAPsMRSA strains were exposed to DAP. Importantly, the combination of DAP and a β-lactam prevented the selection of DAPrvariants. In summary, our data show that the DAP–β-lactam combination may significantly enhance both thein vitroandin vivoefficacy of anti-MRSA therapeutic options against DAPrMRSA infections and represent an option in preventing DAPrselection in persistent or refractory MRSA infections.

scholarly journals A diphtheria toxin resistance marker for in vitro and in vivo selection of stably transduced human cells

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Gabriele Picco ◽  
Consalvo Petti ◽  
Livio Trusolino ◽  
Andrea Bertotti ◽  
Enzo Medico
Keyword(s):  
Diphtheria Toxin ◽  
Human Cells ◽  
Resistance Marker ◽  
Toxin Resistance ◽  
In Vivo Selection ◽  
Selection Of

scholarly journals Rifampin-Resistant Cutibacterium (formerly Propionibacterium) namnetense Superinfection after Staphylococcus aureus Bone Infection Treatment

2018 ◽  
Vol 3 (5) ◽  
pp. 255-257 ◽  
Author(s):  
Stéphane Corvec ◽  
Aurélie Guillouzouic ◽  
Guillaume Ghislain Aubin ◽  
Sophie Touchais ◽  
Olivier Grossi ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Resistant Mutant ◽  
Pyogenic Granuloma ◽  
Rpob Gene ◽  
Bone Infection ◽  
Bacterial Burden ◽  
In Vivo Selection ◽  
Infection Treatment ◽  
Selection Of

Abstract. After rifampin and levofloxacin treatment for a Staphylococcus aureus bone infection, a pyogenic granuloma due to a newly described Cutibacterium species, C. namnetense developed on the tibia former external fixator. This rifampin resistant bacterium, selected during treatment, harbored a mutation in the rpoB gene. This case illustrates the possible in vivo selection of resistant mutant most likely due to the bacterial burden and therefore the importance of adequate bone infection treatment.

Lack of in vitro and in vivo Selection of Bacterial Resistance by Roxithromycin

Chemotherapy ◽  
2000 ◽  
Vol 46 (3) ◽  
pp. 160-165
Author(s):  
Lorenzo Drago ◽  
Maria Cristina Fassina ◽  
Elena De Vecchi ◽  
Barbara Mombelli ◽  
Alessandra Lombardi ◽  
...  
Keyword(s):  
Bacterial Resistance ◽  
In Vivo Selection ◽  
Selection Of

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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