Pharmacodynamics of Antibiotics-Consequences for Dosing: Proceedings of a Symposium Held in Stockholm, June 7–9, 1990

Heteroresistance to cefiderocol in carbapenem-resistant Acinetobacter baumannii in the CREDIBLE-CR study was not linked to clinical outcomes: a post hoc analysis

IMPORTANCE

The population analysis profiling (PAP) test is considered the "gold standard" method to detect heteroresistance. It exposes bacteria to increasing concentrations of antibiotics at high cell densities to detect any minority resistant subpopulations that might be missed by the low inoculums used for reference susceptibility tests. However, its clinical relevance has not been well established. In the CREDIBLE-CR study, a numerically increased all-cause mortality was observed in the cefiderocol arm relative to the best available therapy arm for patients with Acinetobacter spp. infections. Heteroresistance has independently been proposed by another research group as a potential explanation of the mortality difference. An analysis of the baseline carbapenem-resistant Acinetobacter calcoaceticus-baumannii complex isolates from patients treated with cefiderocol in the CREDIBLE-CR study showed the highest clinical cure rate and the lowest mortality for patients with PAP-heteroresistant isolates compared with PAP-susceptible or PAP-resistant isolates. These findings contradict the abovementioned hypothesis that heteroresistance contributed to the increased mortality.

Physiological study of pulmonary involvement in adults with cystic fibrosis through simulated modeling of different clinical scenarios

Cystic fibrosis is an inherited disorder of the cystic fibrosis transmembrane conductance regulator gene (CFTR) that affects the respiratory system. Current treatment is palliative, but there is a gene therapy under investigation which involves inserting a functional CFTR gene into affected cells. Given the clinical variety of the disease, it is necessary to characterize key indicators in its evolution (e.g., the number of functional alveolar sacs and its relationship with a healthy lung function), to anticipate its advancement. A dynamic model was used to evaluate the evolution of cystic fibrosis over time. We considered the application of conventional medical treatments and evaluated the benefits of the application of an experimental gene therapy that would reverse lung damage. Without treatment the life expectancy of the patient is low, but it is increased with the application of conventional treatments, being the progressive loss of the lung function inevitable. Simulating the application of a gene therapy, the life expectancy of patients would not be limited, given the recovery of all altered cellular processes. With this model we can make predictions that demonstrate the need for a curative treatment, in addition to presenting the evolution of pathology in a specific clinical setting. Graphical abstract Graphic representation of the analysis performed in the present work on simulation of different clinical situations regarding patients with cystic fibrosis of pulmonary involvement.

Single-dose antibiotic therapy: what has the past taught us?

The proper dosage schedule of antibiotics has generally been determined empirically, due to the difficulty of clinical trials. Initially, the dosage was chosen to allow high sustained levels greater than MIC in the blood. Antibiotics (beta lactams, tetracyclins, macrolides) were given at high doses three to six times daily, whatever their kinetic properties. The data obtained by Eagle3 with beta lactams in animal models of streptococcal and treponemal infections outlined the importance of interval between doses on the in vivo efficacy. They also showed that increasing the dose of penicillin had a positive effect on the bactericidal activity only through the persistence of effective levels (greater than MIC) at the site of infection. Further illustrations were given through experimental and clinical studies with beta lactams or other compounds on different types of infections: LRTIs, UTIs, meningitis, and endocarditis. The importance of both dynamic (i.e., pattern of bactericidal effect) and kinetic (elimination half-life) parameters was thus further identified. Information on toxicity with some compounds with a narrow therapeutic index, such as aminoglycosides, indicated that increasing the dose to enhance efficacy had some limitations. This led to numerous studies on the relations between concentration and toxicity, stating that nephro- or ototoxicity were not directly related to peak level in serum. Experimental studies showed that OD administration of aminoglycosides was both more efficient and less toxic than the multiple-dose regimen of the same daily amount. Economic considerations progressively justified attempts to both reduce the dose and the work load related to multiple administrations.(ABSTRACT TRUNCATED AT 250 WORDS)