Community-Associated Methicillin-Resistant Staphylococcus aureus: Trends in Case and Isolate Characteristics from Six Years of Prospective Surveillance

• Published in: Public health reports (1974) Vol. 124; no. 3; pp. 427 - 435
• Main Authors: Como-Sabetti, Kathryn, Harriman, Kathleen H., Buck, Jessica M., Glennen, Anita, Boxrud, David J., Lynfield, Ruth
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA Association of Schools of Public Health 01.05.2009; SAGE Publications; SAGE PUBLICATIONS, INC
• Subjects: Adult; Age; Antibiotics; Antimicrobials; Bacterial diseases; Beta lactams; Biological and medical sciences; Child; Child care; Ciprofloxacin - pharmacology; Clindamycin - pharmacology; Clinical outcomes; Community-Acquired Infections - microbiology; Electrophoresis, Gel, Pulsed-Field; Epidemiology; Erythromycin - pharmacology; Human bacterial diseases; Humans; Infections; Infectious diseases; Medical sciences; Medical treatment; Methicillin Resistance; Methicillin resistant staphylococcus aureus; Miscellaneous; Population Surveillance; Prospective Studies; Public health; Public health. Hygiene; Public health. Hygiene-occupational medicine; Staphylococcal Infections - epidemiology; Staphylococcal Infections - microbiology; Staphylococcal infections, streptococcal infections, pneumococcal infections; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus infections; Surveillance; United States - epidemiology; United States; Trend; Infection; Prospective; Surveillance; Characteristics; Bacteriosis; Bacteria; Micrococcales; Isolate; Micrococcaceae; Staphylococcal infection; Community; Public health; Staphylococcus aureus
• ISSN: 0033-3549; 1468-2877
• DOI: 10.1177/003335490912400312

Objectives. In 2000, the Minnesota Department of Health (MDH) implemented active, sentinel site surveillance for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). Data from 2000–2005 were analyzed to determine trends in case characteristics, pulsed-field types (PFTs), and antimicrobial susceptibilities including inducible clindamycin resistance (ICR). Methods. Active sentinel site surveillance was initiated in 2000 at 12 hospital laboratories that served inpatients and outpatients. Patient medical records were reviewed to determine if they met the epidemiologic case criteria for CA-MRSA; isolates were obtained from patients meeting these criteria. The MDH Public Health Laboratory performed pulsed-field gel electrophoresis subtyping and antimicrobial susceptibility testing, including ICR. Results. The proportion of MRSA cases classified as CA increased from 11% to 33% (p<0.01). The proportion of cases with skin or soft tissue infections also increased compared with other infection types from 75% to 87% (p<0.01). During the surveillance period, USA300 replaced USA400 as the dominant PFT. With the change in dominant PFT, the proportion of isolates susceptible to erythromycin (45% to 13%, p<0.01) and ciprofloxacin (80% to 59%, p<0.01) decreased. The proportion of erythromycin-resistant/clindamycin-susceptible isolates with ICR (93% to 14%, p<0.01) decreased. The proportion of susceptible isolates also changed within the USA300 PFT; the proportion of isolates susceptible to erythromycin (33% vs. 3%) and the proportion susceptible to ciprofloxacin (67% to 62%) decreased significantly. Conclusion. CA-MRSA increased dramatically from 2000 to 2005. Changes in the predominant PFT have impacted susceptibility profiles of CA-MRSA, including ICR. Continued surveillance is needed to monitor the changing epidemiology of CA-MRSA and to inform clinical decisions.