aureus isolates recovered from firstly as well as chronically colonized CF patients, over a period of 30 months. The aim of our study was to investigate the genetic diversity of MRSA and MSSA present in the click here sputum of CF children whether sporadically or chronically. The longitudinal survey of genotypes provided information on the variations in those strains recovered from some patients over a maximum period of 24 months. Results Clinical characteristics of S. aureus colonization From a total number of 143 patients AMN-107 purchase attending the Armand Trousseau CF centre during the 30 months study period, 108 provided sputum of which 79 showed one or several cultures positive for S. aureus. It is likely

that most were community-acquired S. aureus contaminations as the majority of patients were outpatients. In addition there was no outbreak episode during the study period. Although this study was not designed see more to correlate the bacteria recovered from the

sputum with the respiratory evolution of the patients, the following features may be underlined: Among the 79 patients, 38 were co-infected with P. aeruginosa, as observed in a previous investigation [22], making it difficult to determine the role of S. aureus in broncho-pulmonary exacerbations. Twenty-four of these patients harboured MSSA, 12 patients harboured MRSA and 2 patients harboured both. MRSA were mainly isolated from older patients who were treated by regular intravenous antibiotic courses, as recommended by the international guidelines. In the 45 other patients,

S. aureus was the single species recovered from sputum cultures (sometimes with intermittent Haemophilus influenzae isolation); MSSA isolates were found in 34 patients, MRSA in 6 patients and both MSSA and MRSA in 5 other patients. These 45 patients were younger than those co-infected with P. aeruginosa. Of note, those harbouring MRSA had more respiratory exacerbations and worse lung function than those harbouring MSSA. Both methicillin-susceptible and methicillin resistant isolates were repeatedly recovered over several months. Forty percent of patients were suffering from their first colonization with S. aureus while in 60% the recurrent isolation of the bacteria was indicative of colonization with exacerbations. In the later cases genotyping could show oxyclozanide in several instances that the strain was different and therefore that several independent infections took place (see paragraph below). Patients were treated by antimicrobial drugs, however in most cases S. aureus was still recovered from sputum samples despite clinical improvement. Investigation of MRSA In total a MRSA isolate was found at least once in 25 patients (33%) with a positive culture. Both screening techniques used here failed to detect the presence of the penicillin binding protein PBP 2a (mecA gene) in the resistant strains from five patients (CFU_29, CFU_41, CFU_48, CFU_51, CFU_68).