359. Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteremia (SAB): Age-Related Trends in the Prevalence of SCCmec types Over 11 y
Session: Poster Abstract Session: MRSA, MSSA, Enterococci
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • Khatib IDSAC2013-Poster editKR 9-23-13 AM.pdf (236.6 kB)
  • Background: Community-associated MRSA isolates (CA-MRSA; prototype SCCmec type IV) emerged among children and young adults about 13-14 years earlier. They spread rapidly and entered healthcare settings. Whether the spreading rate of CA-MRSA is age linked is unknown.

    Methods: Review of adult (≥ 18y) inpatients with SAB prospectively followed during 4 periods: 1/1/2002- 6/30/2003, 11/1/2005-12/31/2006, 7/15/2008-12/31/2009, and 7/15/2010-12/31/2012. SCCmec type of MRSA isolates was defined by multiplex PCR (Applied Biosystems, Foster City, CA). The prevalence of SCCmec types were stratified according to the patient age and study year.

    Results:

    We evaluated 1260 SAB cases, 740 (58.7%) were caused by MRSA. SCCmec II and IV accounted for 410 (55.4%) and 203 (27.4%) isolates, respectively. SCCmec IV increased (5.8, 20.8, 17.3, and 22.4% in year 2002-3, 2005-6, 2008-9, and 2010-12, respectively; p<0.0001 ) and SCCmec II decreased (39.6, 34.5, 27.9, and 27.1%, respectively; p<0.0001) over time. Stratifying the results according to the patient age and study year showed rising SCCmec IV and declining SCCmec II in all age groups (table) but the trend was most significant in patients 51-64 and ≥65 y old.

    SAB: Age and study year-stratified prevalence of SCCmec types

     

    Study year: n (%)

    Age (Y)

    2002-3

    2005-6

    2008-9

    2010-12

    P1

    18-30 (n=34)2

     

     

     

     

         

    SCCmec II

    2/3 (66.7)

    3/10 (30.0)

    2/8 (25.0)

    2/13 (15.4)

    0.07

     

    SCCmec IV

    0/3 (0)

    4/10 (40.0)

    4/8 (50.0)

    9/13 (69.2)

    0.04

     

    SCCmec O3

    1/3 (33.3)

    3/10 (30.0)

    2/8 (25.0)

    2/13 (15.4)

    0.27

    31-50 (n=156)

     

     

     

     

     

    SCCmec II

    21/37 (55.8)

    16/40 (40.0)

    8/40 (20.0)

    12/39 (30.8)

    0.004

     

    SCCmec IV

    11/37 (29.6)

    20/40 (32.8)

    20/40 (50.0)

    17/39 (43.6)

    0.30

     

    SCCmec O

    5/37 (13.5)

    4/40 (10.0)

    12/40 (30.0)

    10/39 (25.6)

    0.06

    51-64 (n=225)

     

     

     

     

     

    SCCmec II

    41/58 (70.7)

    32/61( 52.5)

    20/44 (45.5)

    26/62 (41.9)

    0.001

     

    SCCmec IV

    7/58 (12.1)

    18/61 (29.5)

    12/44 (27.3)

    25/62 (40.3)

    0.002

     

    SCCmec O

    10/58 (17.2)

    11/61 (18.0)

    12/44 (27.3)

    11/62 (17.7)

    0.77

    ≥65 (n=325)

     

     

     

     

     

    SCCmec II

    79/89 (88.8)

    47/75 (62.7)

    52/76 (68.4)

    47/85 (55.3)

    <0.0001

     

    SCCmec IV

    3/89 (3.4)

    17/75 (22.7)

    15/76 (19.7)

    21/85 (24.7)

    0.00074

     

    SCCmec O

    7/89 (7.9)

    11/75 (14.7)

    9/76 (11.8)

    17/85 (20.0)

    0.04

    1: Extended Mantel-Haenszel chi square for linear trend; 2: all MRSA cases; 3: nontypeable/other types.

    Conclusion:

    CA-MRSA continues to take-over HCA-MRSA in all age groups with more noticeable trends in patients 51-64 and ≥65 year-old. Whether it will eventually replaces HCA-MRSA remains to be determined.

    Riad Khatib, MD1, Mamta Sharma, MD2, Leonard Johnson, MD1, Kathleen Riederer, BS, MT3, Stephen Shemes, BS1 and Kristian Cruz, BS3, (1)Medicine, St. John Hospital and Medical Center, Grosse Pointe Woods, MI, (2)St. John Hospital and Medical Center, Grosse Pointe Woods, MI, (3)Graduate Medical Education, St. John Hospital and Medical Center, Grosse Pointe Woods, MI

    Disclosures:

    R. Khatib, None

    M. Sharma, None

    L. Johnson, None

    K. Riederer, None

    S. Shemes, None

    K. Cruz, None

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