Frequency of Small-Colony Variants and Antimicrobial Susceptibility of Methicillin-Resistant Staphylococcus aureus in Cystic Fibrosis Patients

Publication date: Available online 2 December 2017
Source:Diagnostic Microbiology and Infectious Disease
Author(s): Nuntra Suwantarat, Mayer Rubin, Latetia Bryan, Tsigereda Tekle, Michael P. Boyle, Karen C. Carroll, Mark T. Jennings
BackgroundSmall-colony variants (SCVs) are a distinct phenotype of S. aureus, known for their role in chronic, difficult to treat infections, including cystic fibrosis (CF) lung disease. The goal of this study was to characterize SCV MRSA infection in an adult and pediatric CF population and to identify antibiotic susceptibility patterns unique to SCV MRSA.MethodsWe recovered methicillin-resistant Staphylococcus aureus (MRSA) from respiratory culture samples from CF patients at the Johns Hopkins Hospital during a 6month study period.ResultsOf 1161 samples, 200 isolates (17%) were identified as MRSA, and 37 isolates from 28 patients were identified as SCV MRSA. A higher proportion of MRSA was found among SCV isolates (37/66, 56%) compared to normal colony variant (NCV) isolates (163/417, 39%), p=0.02. All SCV MRSA isolates from individual patients were susceptible to vancomycin and ceftaroline, but they demonstrated higher rates of antibiotic resistance to trimethoprim/sulfamethoxazole, moxifloxacin, and erythromycin, compared to NCV MRSA isolates. Additionally, individuals with SCV MRSA had lower lung function, higher rates of persistent MRSA infection, and higher rates of previous antibiotic use, compared to individuals with NCV MRSA.ConclusionsA significant proportion of MRSA isolates recovered from patients with CF have the SCV morphology. Compared to individuals with NCV MRSA, those with SCV MRSA have higher rates of persistent MRSA infection and lower lung function. SCV MRSA isolates were more resistant than NCV, but they are highly susceptible to vancomycin, linezolid and ceftaroline.



from ! ORL Sfakianakis via paythelady.61 on Inoreader http://ift.tt/2iDYeb8
via IFTTT