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Detection and Characterization of Antibiotic Resistant S. aureus from Cystic Fibrosis Patient Isolates

Detection and Characterization of Antibiotic Resistant S. aureus from Cystic Fibrosis Patient Isolates

Rawan Eleshy

Microbiology and Molecular Genetics

Cystic fibrosis (CF) is a common genetic disease caused by a mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Mutations within this gene inhibit the function of the chloride ion channels across epithelial membranes. This leads to the formation of thick mucus within the lung airways of CF patients. Therefore, the CF lung becomes an excellent environment for bacterial colonization. S. aureus is the first pathogen to colonize the lungs and tends to persist throughout the lives of CF patients. S. aureus is known for its ability to develop resistance against antibiotics. Antibiotic resistance is one of the biggest problems faced in medicine today. This study aims to detect and characterize the resistance of S. aureus obtained from CF patients of various age groups to a panel of clinically relevant antibiotics. Based on findings from previous studies, there are nine antibiotic resistance genes in S. aureus that have been correlated with CF patients. Using PCR amplification, we checked if any of these resistance genes are present in the CF isolates. In addition, we performed antibiotic susceptibility tests to determine if these isolates exhibit a resistant phenotype. Minimum inhibitory concentrations (MIC’s) of each antibiotic to each isolate were determined to further confirm resistance. In conclusion, the presence of resistance genes and susceptibility to antibiotics differ among CF patients. CF isolates showed both susceptibility and resistance to the tested antibiotics, but the percentage of resistant isolates was higher. The interesting finding was that resistance to antibiotics, in some isolates, did not correlate with the presence of resistance genes. The lack of resistance genes in isolates that showed a resistant phenotype to antibiotics suggests that S. aureus is using other mechanisms to acquire resistance. This study shines the light on understanding S. aureus as a CF pathogen and its resistance within the CF lung. This will aid in enhancing treatment options for CF patients to help them live longer and more productive lives.