Pulmonary infections are usually caused by bacterial microorganisms such as Pseudomonas aeruginosa, Staphylococcus aureus, Haemophilus influenzae, and Burkholderia cepacia complex in cystic fibrosis (CF) patients. Unusual bacteria (UB) have been described by new isolation techniques recently in the respiratory samples of CF patients. The aim is to investigate the effects of the presence of UB in the respiratory cultures of CF patients on clinical outcomes, necessity of treatment and prognosis. The UB were identified by MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry technology. Rhizobium radiobacter were detected in 2, Chyrseobacterium species (gleum and indolgenes) in 5, Aeromonas hydrophila in 1, Orchobacterium anthropy in 1,Wautersiella falsenii in 1, Leclercia adecarboxylata in 1, Delftia acidovorans in 1, Cupriavidus Gilardi in 1, R.radiobacter twith Elizabethkingia miricola in 1 and R.radiobacter with C.gleum in 1 patient. Median age of the first UB growth was 3 years. After the first UB growth, the median follow-up time was 15 months. Before the UB growth, 60.0% of the patients had respiratory colonization with methicillin-susceptible S.aureus (MSSA). UB growth were accompanied with MSSA in 66.6% of the patients. Median percentage of FEV1 before and during the UB growth for patients who could perform spirometry, were 80 and 102, respectively. Median body mass index before and during the UB growth were 16 and 16.2, respectively. These UB were not detected during the follow-ups except in one patient. The UB growth did not cause any additional symptoms and decrease in BMI and FEV1 in patients with CF. MSSA may be a facilitating factor for UB growth as majority of the patients had MSSA colonization before and during the UB growth.