In-vitro selection of resistance of Staphylococcus aureus to teicoplanin and vancomycin

1990 ◽  
Vol 25 (1) ◽  
pp. 69-72 ◽  
Author(s):  
Chatrchai Watanakunakorn
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Selection ◽  
Selection Of ◽  
Selection Of Resistance

The Effects of Shock Vancomycin Concentrations on the Formation of Heteroresistance in Staphylococcus aureus

2020 ◽  
Vol 65 (9-10) ◽  
pp. 3-7
Author(s):  
V. V. Gostev ◽  
Yu. V. Sopova ◽  
O. S. Kalinogorskaya ◽  
M. E. Velizhanina ◽  
I. V. Lazareva ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Selection ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
High Concentration ◽  
Short Term ◽  
High Concentrations ◽  
Selection Of ◽  
Selection Of Resistance ◽  
Test Cultures

Glycopeptides are the basis of the treatment of infections caused by MRSA (Methicillin-Resistant Staphylococcus aureus). Previously, it was demonstrated that antibiotic tolerant phenotypes are formed during selection of resistance under the influence of high concentrations of antibiotics. The present study uses a similar in vitro selection model with vancomycin. Clinical isolates of MRSA belonging to genetic lines ST8 and ST239, as well as the MSSA (ATCC29213) strain, were included in the experiment. Test isolates were incubated for five hours in a medium with a high concentration of vancomycin (50 μg/ml). Test cultures were grown on the medium without antibiotic for 18 hours after each exposure. A total of ten exposure cycles were performed. Vancomycin was characterized by bacteriostatic action; the proportion of surviving cells after exposure was 70–100%. After selection, there was a slight increase in the MIC to vancomycin (MIC 2 μg/ml), teicoplanin (MIC 1.5–3 μg/ml) and daptomycin (MIC 0.25–2 μg/ml). According to the results of PAP analysis, all strains showed an increase in the area under curve depending on the concentration of vancomycin after selection, while a heteroresistant phenotype (with PAP/AUC 0.9) was detected in three isolates. All isolates showed walK mutations (T188S, D235N, E261V, V380I, and G223D). Exposure to short-term shock concentrations of vancomycin promotes the formation of heteroresistance in both MRSA and MSSA. Formation of VISA phenotypes is possible during therapy with vancomycin.

In vitro selection of resistance to sofosbuvir in HCV replicons of genotype 1 to 6

2017 ◽  
Vol 22 (7) ◽  
pp. 587-597 ◽  
Author(s):  
Simin Xu ◽  
Brian Doehle ◽  
Sonal Rajyaguru ◽  
Bin Han ◽  
Ona Barauskas ◽  
...  
Keyword(s):  
In Vitro Selection ◽  
Genotype 1 ◽  
Selection Of ◽  
Selection Of Resistance

scholarly journals In vitro selection of Staphylococcus aureus mutants resistant to tigecycline with intermediate susceptibility to vancomycin

2016 ◽  
Vol 15 (1) ◽  
Author(s):  
Melina Herrera ◽  
Sabrina Di Gregorio ◽  
Silvina Fernandez ◽  
Graciela Posse ◽  
Marta Mollerach ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Selection ◽  
Selection Of

scholarly journals Clinical Isolate of Vancomycin-HeterointermediateStaphylococcus aureus Susceptible to Methicillin and In Vitro Selection of a Vancomycin-Resistant Derivative

2001 ◽  
Vol 45 (1) ◽  
pp. 349-352 ◽  
Author(s):  
Sophie Bobin-Dubreux ◽  
Marie-Elisabeth Reverdy ◽  
Chantal Nervi ◽  
Martine Rougier ◽  
Anne Bolmström ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Clinical Isolate ◽  
Electron Micrographs ◽  
Parent Strain ◽  
In Vitro Selection ◽  
Glycopeptide Antibiotics ◽  
Vancomycin Resistant ◽  
Selection Of

ABSTRACT A Staphylococcus aureus strain with low-level heteroresistance to vancomycin (designated MER) but susceptible to methicillin was isolated from an outpatient with conjunctivitis who did not receive any glycopeptide antibiotics. Incubation of the parent strain, MER, with increasing concentrations of vancomycin led to rapid selection of a stable progeny homogeneously resistant to vancomycin. Electron micrographs of strain MER showed enhanced cell wall thickness and abnormal septations typically seen with methicillin-resistantS. aureus having intermediate susceptibility to vancomycin.

scholarly journals In Vitro Selection of Resistance to Four β-Lactams and Azithromycin in Streptococcus pneumoniae

1998 ◽  
Vol 42 (11) ◽  
pp. 2914-2918 ◽  
Author(s):  
Glenn A. Pankuch ◽  
Shane A. Jueneman ◽  
Todd A. Davies ◽  
Michael R. Jacobs ◽  
Peter C. Appelbaum
Keyword(s):  
Streptococcus Pneumoniae ◽  
In Vitro Selection ◽  
Antimicrobial Agents ◽  
Penicillin G ◽  
Resistance Selection ◽  
Resistant Strains ◽  
Selection Of ◽  
Selection Of Resistance

ABSTRACT Selection of resistance to amoxicillin (with or without clavulanate), cefaclor, cefuroxime, and azithromycin among six penicillin G- and azithromycin-susceptible pneumococcal strains and among four strains with intermediate penicillin sensitivities (azithromycin MICs, 0.125 to 4 μg/ml) was studied by performing 50 sequential subcultures in medium with sub-MICs of these antimicrobial agents. For only one of the six penicillin-susceptible strains did subculturing in medium with amoxicillin (with or without clavulanate) lead to an increased MIC, with the MIC rising from 0.008 to 0.125 μg/ml. Five of the six penicillin-susceptible strains showed increased azithromycin MICs (0.5 to >256.0 μg/ml) after 17 to 45 subcultures. Subculturing in medium with cefaclor did not affect the cefaclor MICs of three strains but and led to increased cefaclor MICs (from 0.5 to 2.0 to 4.0 μg/ml) for three of the six strains, with MICs of other β-lactams rising 1 to 3 twofold dilutions. Subculturing in cefuroxime led to increased cefuroxime MICs (from 0.03 to 0.06 μg/ml to 0.125 to 0.5 μg/ml) for all six strains without significantly altering the MICs of other β-lactams, except for one strain, which developed an increased cefaclor MIC. Subculturing in azithromycin did not affect β-lactam MICs. Subculturing of the four strains with decreased penicillin susceptibility in amoxicillin (with or without clavulanate) or cefuroxime did not select for β-lactam resistance. Subculturing of one strain in cefaclor led to an increase in MIC from 0.5 to 2.0 μg/ml after 19 passages. In contrast to strains that were initially azithromycin susceptible, which required >10 subcultures for resistance selection, three of four strains with azithromycin MICs of 0.125 to 4.0 μg/ml showed increased MICs after 7 to 13 passages, with the MICs increasing to 16 to 32 μg/ml. All azithromycin-resistant strains were clarithromycin resistant. With the exception of strains that contained mefE at the onset, no strains that developed resistance to azithromycin containedermB or mefE, genes that have been found in macrolide-resistant pneumococci obtained from clinic patients.

In vitro selection of resistance in haemophilus influenzae by 4 quinolones and 5 β-lactams

2004 ◽  
Vol 49 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Catherine Clark ◽  
Klaudia Kosowska ◽  
Bülent Bozdogan ◽  
Kim Credito ◽  
Bonifacio Dewasse ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
In Vitro Selection ◽  
Selection Of ◽  
Selection Of Resistance

In vitro selection of resistance to pradofloxacin and ciprofloxacin in canine uropathogenic Escherichia coli isolates

2014 ◽  
Vol 174 (3-4) ◽  
pp. 514-522 ◽  
Author(s):  
Xiaoqiang Liu ◽  
Caterina Lazzaroni ◽  
Sherine A. Aly ◽  
Kamoltip Thungrat ◽  
Dawn M. Boothe
Keyword(s):  
Escherichia Coli ◽  
In Vitro Selection ◽  
Uropathogenic Escherichia Coli ◽  
Selection Of ◽  
Selection Of Resistance
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