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  • Use of Aerosolized Antibiotics in Patients With Cystic Fibrosis: Recommendations for Addressing Microbiological Implications of Aerosolized Antibiotics

Recommendations for Addressing Microbiological Implications of Aerosolized Antibiotics
1.    It is strongly recommended that all efforts be made to define a breakpoint to correlate in vitro susceptibility with in vivo efficacy for antibiotics delivered by the aerosol route, because at present, there are inadequate data to establish this breakpoint (consensus grade I to III).
Comment: The National Committee for Clinical Laboratory Standards defines MIC breakpoints for parenteral tobramycin as follows: > 4 ^g/mL, susceptible; 8 ^g/mL, intermediate; and > 16 ^g/mL. resistant. These levels are derived from an assessment of clinically achievable antibiotic concentration in serum, the relatively narrow therapeutic index* needed to avoid nephrotoxicity and ototoxicity, and studies of clinical efficacy. It is well recognized that much higher drug concentrations can be achieved by the aerosol route. This is in part necessary to overcome the inhibitory effects of sputum on drug bioactivity. It also has the potential benefits of overwhelming certain mechanisms of resistance and of possibly allowing penetration of antibiotics into biofilms. cialis professional 20 mg

2.    Standardized method for determination of high-level resistance needs to be established for CF isolates of P aeruginosa (consensus grade III).
Comment: Currently, most commercially available susceptibility testing cannot detect high-range MICs (> 8 ^g/mL). However, conventional antibiotic susceptibility testing is still necessary for parenteral agents, and clinical microbiology laboratories should continue to employ National Committee for Clinical Laboratory Standards standards for antibiotic susceptibility testing. At present, the best method for determining antibiotic susceptibility for strains with MICs beyond conventional levels of resistance is uncertain. Thus, it is critical to establish a standardized method for in vitro testing of high-level antibiotic resistance that can be used in all settings. Clinical measures should be used to assess aerosolized antimicrobial efficacy rather than in vitro antibiotic susceptibility.
3.    The presence of P aeruginosa is a microbiological indication for the use of aerosolized antibiotics. There are no absolute microbiological contraindications to the use of aerosolized antibiotics. Patients who have either high-level or multiply resistant P aeruginosa or other intrinsically resistant organisms such as B cepacia should not be excluded from receiving aerosolized antibiotics (consensus grade III).

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