557.  Epidemiology of SCCmec IV Methicillin-Resistant Staphylococcus aureus Infections in a Tertiary Level Facility in Central Illinois
Session: Poster Abstract Session: MRSA Surveillance and Infection Prevention
Friday, October 21, 2011
Room: Poster Hall B1
Background: Historically, the vast majority of community-associated methicillin-resistant S. aureus (CA-MRSA) have been associated with SCCmec IV or V. However, reports of SCCmec IV MRSA infections with multidrug resistant phenotypes associated with nosocomial acquisition are increasing. We aimed to determine the epidemiology and trends in antimicrobial resistance profiles among SCCmec IV MRSA at our 450 bed tertiary referral center.

Methods: MRSA isolates were collected from clinical specimens between 2004-2008. Clinical characteristics and healthcare-associated risk factors for MRSA acquisition were reviewed. MRSA infections were classified as community onset if the isolate was collected within 72 hours of admission. Antimicrobial susceptibility testing was performed by disk diffusion. Multidrug resistance (MDR) was defined as resistance to ≥ 3 non-β-lactam antimicrobial agents.  Molecular typing of SCCmec was determined by PCR.  The prevalence of SCCmec IV in period 1 isolates (2004-2006) was compared to prevalence in period 2 isolates (2007-2008).

Results: SCCmec IV was identified in 144 (32.5%) of the 443 MRSA isolates evaluated.  33% of patients with community-onset SCCmec IV MRSA infections had ≥ 1 risk factors for MRSA acquisition. Presence of an invasive medical device was associated with non SCCmec IV infections (P < 0.001).The prevalence of SCCmec IV increased from 23.2% during period 1 to 38.7 % in period 2. The majority of MRSA infections associated with SCCmec IV were skin and soft tissue infections (70.2%), categorized as community onset (89%). The prevalence of nosocomial-onset SCCmec IV MRSA infections was 9.7 % in period 1 and 11.7% in period 2. 15.4% of SCCmec IV MRSA were isolated from blood, 23% of these were nosocomial-onset infections.  The majority of SCCmec IV MRSA were susceptible to clindamycin (90.9%), trimethoprim-sulfamethoxazole (99.3%) and vancomycin (100%).  None of the SCCmec IV isolates met MDR criteria in period 1 but  13% met MDR criteria (P=0.02) in period 2.

Conclusion: SCCmec IV MRSA infections are common in our institution and increased in prevalence between period 1 and period 2 samples. Our findings emphasize the importance of continuous monitoring of SCCmec IV MRSA susceptibility patterns.

Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

Sudha Nagalingam, MD1, Vibhave Pal, MD1, John Farrell, MD2, Huaping WANG, PhD3, Barry Gray, MD4 and Kanokporn Mongkolrattanothai, MD4, (1)Internal Medicine, University of IL College of Medicine, Peoria, IL , Peoria, IL, (2)Infectious Disease, University of Illinois College of Medicine, Peoria, IL, (3)University of Illinois College of Medicine, Peoria, Peoria, IL, (4)University of IL College of Medicine, Peoria, IL


S. Nagalingam, None

V. Pal, None

J. Farrell, None

H. WANG, None

B. Gray, None

K. Mongkolrattanothai, None

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