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Antimicrobial activity of tobramycin against respiratory cystic fibrosis Pseudomonas aeruginosa isolates from Bulgaria.
J Chemother. 2010 Dec; 22(6):378-83.JC

Abstract

Tobramycin solution for inhalation (TSI) (Novartis pharmaceuticals) is indicated as chronic suppressive treatment for cystic fibrosis (CF) patients aged 6 years and older who are chronically infected by Pseudomonas aeruginosa . Inhaled administration of tobramycin assures high concentrations in the lungs of CF patients, improving the therapeutic ratio over that of parenteral tobramycin levels. Clinical and laboratory Standards institute (CLSI) breakpoints only consider parenteral levels and do not take into account these high antimicrobial concentrations. Therefore, the Spanish meNSURA Group has defined specific values for inhaled tobramycin when testing CF P. aeruginosa isolates (susceptible: minimal inhibitory concentration (MIC) ≤ 64 μg/ml; resistant: ≥ 128 μg/ml). In this study the antimicrobial activity of tobramycin against 120 respiratory CF P. aeruginosa isolates was determined by high-range etest strips (LIOFILCHEM). Applying MENSURA breakpoints, 95% of the strains were categorized as susceptible. With CLSI breakpoints, the susceptibility rate decreased to 92.5%. The activity against non-mucoid P. aeruginosa was higher than that against mucoid isolates (MIC(50)=0.75 and MIC(90)=2 μg/ml vs. MIC(50)=1 and MIC(90)=4 μg/ml). The isolates obtained from patients untreated with TSI were more susceptible to the drug than those from patients receiving maintenance therapy with TSI (MIC(50)=0.75 and MIC(90) =1.5 μg/ml vs. MIC(50)=1.5 and MIC(90)=6 μg/ml). The isolates from patients with long-term P. aeruginosa colonization (over 5 years) revealed the highest tobramycin MICs (MIC(50)=1.00 and MIC(90)>1024 μg/ml). In conclusion, tobramycin has excellent in vitro activity against the studied CF isolates. Some factors such as isolate morphotype, pre-administration of TSI and duration of colonization influence its activity. Whenever TSI is considered for therapy, the CF P. aeruginosa strains categorized as intermediate or resistant to tobramycin according to the CLSI criteria should be recategorized by using the MENSURA interpretive criteria.

Authors+Show Affiliations

Deaprtment of Medical Microbiology and 1 Pediatric Clinic, Alexandrovska University Hospital, Medical University of Sofia, Bulgaria. dr.strateva@abv.bgNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

21303744

Citation

Strateva, T, et al. "Antimicrobial Activity of Tobramycin Against Respiratory Cystic Fibrosis Pseudomonas Aeruginosa Isolates From Bulgaria." Journal of Chemotherapy (Florence, Italy), vol. 22, no. 6, 2010, pp. 378-83.
Strateva T, Petrova G, Mitov I. Antimicrobial activity of tobramycin against respiratory cystic fibrosis Pseudomonas aeruginosa isolates from Bulgaria. J Chemother. 2010;22(6):378-83.
Strateva, T., Petrova, G., & Mitov, I. (2010). Antimicrobial activity of tobramycin against respiratory cystic fibrosis Pseudomonas aeruginosa isolates from Bulgaria. Journal of Chemotherapy (Florence, Italy), 22(6), 378-83.
Strateva T, Petrova G, Mitov I. Antimicrobial Activity of Tobramycin Against Respiratory Cystic Fibrosis Pseudomonas Aeruginosa Isolates From Bulgaria. J Chemother. 2010;22(6):378-83. PubMed PMID: 21303744.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Antimicrobial activity of tobramycin against respiratory cystic fibrosis Pseudomonas aeruginosa isolates from Bulgaria. AU - Strateva,T, AU - Petrova,G, AU - Mitov,I, PY - 2011/2/10/entrez PY - 2011/2/10/pubmed PY - 2011/6/10/medline SP - 378 EP - 83 JF - Journal of chemotherapy (Florence, Italy) JO - J Chemother VL - 22 IS - 6 N2 - Tobramycin solution for inhalation (TSI) (Novartis pharmaceuticals) is indicated as chronic suppressive treatment for cystic fibrosis (CF) patients aged 6 years and older who are chronically infected by Pseudomonas aeruginosa . Inhaled administration of tobramycin assures high concentrations in the lungs of CF patients, improving the therapeutic ratio over that of parenteral tobramycin levels. Clinical and laboratory Standards institute (CLSI) breakpoints only consider parenteral levels and do not take into account these high antimicrobial concentrations. Therefore, the Spanish meNSURA Group has defined specific values for inhaled tobramycin when testing CF P. aeruginosa isolates (susceptible: minimal inhibitory concentration (MIC) ≤ 64 μg/ml; resistant: ≥ 128 μg/ml). In this study the antimicrobial activity of tobramycin against 120 respiratory CF P. aeruginosa isolates was determined by high-range etest strips (LIOFILCHEM). Applying MENSURA breakpoints, 95% of the strains were categorized as susceptible. With CLSI breakpoints, the susceptibility rate decreased to 92.5%. The activity against non-mucoid P. aeruginosa was higher than that against mucoid isolates (MIC(50)=0.75 and MIC(90)=2 μg/ml vs. MIC(50)=1 and MIC(90)=4 μg/ml). The isolates obtained from patients untreated with TSI were more susceptible to the drug than those from patients receiving maintenance therapy with TSI (MIC(50)=0.75 and MIC(90) =1.5 μg/ml vs. MIC(50)=1.5 and MIC(90)=6 μg/ml). The isolates from patients with long-term P. aeruginosa colonization (over 5 years) revealed the highest tobramycin MICs (MIC(50)=1.00 and MIC(90)>1024 μg/ml). In conclusion, tobramycin has excellent in vitro activity against the studied CF isolates. Some factors such as isolate morphotype, pre-administration of TSI and duration of colonization influence its activity. Whenever TSI is considered for therapy, the CF P. aeruginosa strains categorized as intermediate or resistant to tobramycin according to the CLSI criteria should be recategorized by using the MENSURA interpretive criteria. SN - 1973-9478 UR - https://www.unboundmedicine.com/medline/citation/21303744/Antimicrobial_activity_of_tobramycin_against_respiratory_cystic_fibrosis_Pseudomonas_aeruginosa_isolates_from_Bulgaria_ L2 - https://www.tandfonline.com/doi/full/10.1179/joc.2010.22.6.378 DB - PRIME DP - Unbound Medicine ER -