Antimicrobial susceptibility and molecular typing of MRSA in cystic fibrosis

Abstract

In this U.S. study, most MRSA isolates in the pediatric CF population were SCCmec II PVL negative. Rates of resistance were low, including to older and orally available antibiotics such as trimethoprim-sulfamethoxazole.

Outcomes and Treatment of Chronic Methicillin-ResistantStaphylococcus aureusDiffers by Staphylococcal Cassette Chromosomemec(SCCmec) Type in Children With Cystic Fibrosis

“…Bacterial factors related to S aureus type with potential impact include antibiotic susceptibilities, virulence factors, or bacterial fitness. Although some non-CF studies show that a higher vancomycin minimal inhibitory concentration has been associated with worse outcomes [31], we did not see vancomycin-resistant or vancomycin-intermediate isolates in this study [22]. Other bacterial factors were not assessed in this study and would only be speculative.…”

“…We have previously shown that the SCCmec II strains were more often resistant to clindamycin and ciprofloxacin compared with the SCCmec IV strains [22]. We found that linezolid was used more often in those with SCCmec type II compared to SCCmec IV, which may be reflective of these differences in antimicrobial susceptibilities.…”

“…Three colonies of MRSA from the same culture were sent to the core laboratory at the University of North Carolina to determine the SCCmec type and presence of the PVL gene using polymerase chain reaction methods previously described [15,22,23]. Treating physicians were not informed about the typing results.…”

Changing Epidemiology of the Respiratory Bacteriology of Patients With Cystic Fibrosis

“…Support for this can be derived from molecular-typing studies that have demonstrated that approximately 65% to 70% of patients with CF harbor health-care-associated clones and about one-third of patients with CF harbor CA clones. [27][28][29] Furthermore, older patients with CF are more likely to harbor hospitalassociated clones, suggesting acquisition prior to the widespread onset of CA MRSA. 30 Support for acquisition of MRSA in health-care settings is provided by a report that found that more stringent infection prevention and control strategies, which included universal contact precautions, significantly reduced MRSA in a pediatric CF clinic.…”

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

“…In a multicenter study conducted in the United States from 2008 to 2010, SCCmec type II strains were more common than SCCmec type IV strains, accounting for 71% of MRSA isolates, and 84% of SCCmec type IV strains that harbored Panton-Valentine leukocidin were USA300, the most common community-associated MRSA clone. 220 In a multicenter study conducted in Italy, MLST analysis revealed common types in multiple individuals with CF attending multiple CF centers. 139 Twenty-nine strains from 6 CF centers were identified as ST8 SCCmec type IV (USA), and 26 strains from 6 CF centers were identified as ST5 SCCmec type I (also a healthcare-associated clone initially reported from the United Kingdom).…”