Pseudomonas aeruginosa Type III Secretion System Virulotypes and Their Association with Clinical Features of Cystic Fibrosis Patients

appears as the main pathogen in cystic fibrosis (CF) involved in recurrent pneumonia and pulmonary exacerbations. The type III secretion system (T3SS) is one of its main determinants of virulence and is associated with poor clinical progression and increased mortality. This study determined the relationship of clinical features of patients with CF and T3SS virulotypes. From January 2018 to March 2019, were isolated from sputum and/or oropharyngeal swabs. T3SS markers ( and ) were detected by PCR. Clinical severity according to Shwachman-Kulckycki score and spirometry data were associated with T3SS virulotypes. A total of 49 patients had positive cultures for . T3SS virulence-related markers were detected as follows: 97.9% (n=48), 63.2% (n=31), 95.9% (n=47) and 97.9% (n=48). The prevalence of virulotype was higher than previously reported in CF settings, being detected in 61.2% of the evaluated isolates, present in 70% of intermittent infections and with a significantly higher frequency in cases of exacerbations. The presence of in chronic infection was not associated with poor clinical results. In chronic infections, the virulotype prevailed (77.8%) and was associated to worse clinical results according to the Shwachman-Kulckycki score and spirometric. Our findings revealed a high prevalence of the atypical virulotype among isolates from patients with CF, which was associated with intermittent infection and early clinical alterations, while the virulotype was associated with chronic infection and worse clinical results. Finally, the presented data highlight the relevance of T3SS virulence markers in the clinical progression and disease severity in CF patients.