Methods: Severe CA-SA has been reportable in MN since 2005, defined as culture-confirmed SA infection with fatal illness or ICU admission and no healthcare-associated risk factors. Submitted isolates underwent susceptibility testing and PFGE.
135 cases were reported during 2005–2013: 61(45%) MRSA, 74(54%) MSSA. MRSA and MSSA median age was 36 and 17 years, respectively (p=0.02), and 29(48%) MRSA and 39(53%) MSSA cases were male. Non-whites (35%) were disproportionately affected (versus 14% non-whites in MN, p<0.01). 60(46%) patients had ≥1 comorbidities.
Pneumonia was more common with MRSA (34, 56%) than MSSA (23, 31%) infection (p<0.01). Skin-associated infections (p=0.04) and toxic shock syndrome (p<0.01) were more common with MSSA. Bacteremia, endocarditis, septic arthritis, meningitis, and internal abscesses did not differ for MRSA and MSSA. Multifocal infections occurred in 20(33%) MRSA, 11(15%) MSSA.
18(30%) MRSA and 19(26%) MSSA cases died. Case fatality rate did not differ for MRSA and MSSA by race or sex. Median age of fatal cases was 45 years. Of 37 fatal cases, 25(68%) involved pneumonia. All 7 patients with influenza died.
52 MRSA and 59 MSSA isolates were characterized. MRSA isolates showed resistance to more non-beta-lactam antibiotics than MSSA (p<0.01). Clonal group USA300 was most common: 42 (81%) MRSA and 4(7%) MSSA. USA300 patients were more likely to have COPD (p<0.01) and smoke (p=0.03). A USA300-pneumonia association was attenuated after smoking, COPD adjustment (p=0.05).
Conclusion: Severe CA-MRSA and MSSA infections occurred in young people, were more common in non-whites, and caused considerable mortality. Pneumonia was common, often fatal, especially if influenza was also diagnosed. USA300 was frequent among MRSA. Surveillance can help inform vaccine development and other control measures.
M. Koeck, None
S. Jawahir, None
D. Boxrud, None
K. Como-Sabetti, None
A. Glennen, None
P. Snippes Vagnone, None
R. Lynfield, None