Clinical and genetic risk factors for biofilm-forming Staphylococcus aureus [PublishAheadOfPrint]

Background. Molecular and clinical factors associated with biofilm-forming methicillin-resistant Staphylococcus aureus (MRSA) are incompletely understood.

Methods. Biofilm production was quantified in 182 MRSA isolates from clinical culture sites (2004-2013). Microbiologic toxins, pigmentation, and genotypes were evaluated, and patient demographics were collected. Logistic regression was used to quantify the effect of strong biofilm production (versus weak) on clinical outcomes and independent predictors of strong biofilm.

Results. Of isolates evaluated, 25.8% (47/182) produced strong biofilm, and 40.7% (74/182) produced weak biofilm. Strong biofilm-producing isolates were more likely to be from MLST clonal complex 8 (34.0% vs. 14.9%; P=0.01), but less likely to be from MLST CC5 (48.9% vs. 73.0%, P=0.007). Predictors for strong biofilm were spa type t008 (aOR 4.54 95%CI 1.21-17.1), and receiving chemotherapy or immunosuppressants in the previous 90 days (aOR 33.6; 95%CI 1.68-673). Conversely, patients with high serum creatinine (aOR 0.33; 95%CI 0.15-0.72) or who previously received vancomycin (aOR 0.03; 95%CI 0.002-0.39) were less likely to harbor strong biofilm-producing MRSA. Beta-toxin producing isolates (aOR 0.31; 95%CI 0.11-0.89) and isolates with spa type t895 (aOR 0.02 95%CI <0.001-0.47) were less likely to produce strong biofilm. Patient outcomes also varied between the two groups. Specifically, patients with strong biofilm-forming MRSA were significantly more likely to be readmitted within 90 days (aOR 5.43; 95%CI 1.69-17.4), but tended to have decreased 90 day mortality (aOR 0.36; 95%CI 0.12-1.06).

Conclusions: Patients that harbored t008 and received immunosuppressants were more likely to have a strong biofilm-producing MRSA. Clinically, patients with strong biofilm-forming MRSA were less likely to die at 90 days, but five times more likely to be re-admitted.

http://ift.tt/2FChXOO