Is there value in susceptibility testing ofPseudomonas aeruginosacausing chronic infection in patients with cystic fibrosis?

Pharmacokinetics and Pharmacodynamics of Aerosolized Antibacterial Agents in Chronically Infected Cystic Fibrosis Patients

“…The author of this study concludes that in agreement with previous studies on the use of aerosolized combination therapy of tobramycin and azlocillin as well as the triple combination of tobramycin plus azlocillin and ticarcillin-clavulanic acid (Timentin), conventional measures of antimicrobial resistance may underestimate the clinical efficacy of tobramycin and colistin when delivered at the high concentrations achieved with the TSI formulation (320)(321)(322). These findings are in agreement with the poor predictability of clinical success by conventional susceptibility testing (31,79,80,(118)(119)(120)(121)(122)(123).…”

“…Early isolates of P. aeruginosa have not yet acquired the phenotypic and genotypic responses to a chronic infection, so almost all P. aeruginosa isolates associated with early infection were drug susceptible (76)(77)(78). Thus, conventional susceptibility testing of CF isolates is poorly predictive of the clinical response (31,79,80).…”

Incidence and Risk Factors for Pulmonary Exacerbation Treatment Failures in Patients With Cystic Fibrosis Chronically Infected With Pseudomonas aeruginosa

“…This has resulted in some centers reducing the frequency with which susceptibility testing is performed 34 and others to question whether any role remains for routine susceptibility testing of CF P aeruginosa isolates. 35 The present results suggest the continued use of classic susceptibility testing of individual morphotypes of P aeruginosa and that the delivery of antibacterial therapies based on these results can play a role in management of PEx.…”

Role of persister cells in chronic infections: clinical relevance and perspectives on anti-persister therapies

“…Resistanceconferring mutations do occur, probably selected for by intensive antibiotic treatments. However, isolates of P. aeruginosa strains do not always develop resistance (Burns et al, 1999;Gibson et al, 2003;Gilligan, 2006;Mulcahy et al, 2010). Lewis (2007) suggested that the recalcitrant nature of P. aeruginosa infections in CF lungs is largely the consequence of the presence of a drug-tolerant subpopulation of persister cells.…”