Differences in Methicillin-Resistant Staphylococcus aureus Strains Isolated from Pediatric and Adult Patients from Hospitals in a Large County in California

Abstract

Studies of U.S. epidemics of community-and health care-associated methicillin-resistant Staphylococcus aureus (MRSA) suggested differences in MRSA strains in adults and those in children. Comprehensive population-based studies exploring these differences are lacking. We conducted a prospective cohort study of inpatients in Orange County, CA, collecting clinical MRSA isolates from 30 of 31 Orange County hospitals, to characterize differences in MRSA strains isolated from children compared to those isolated from adults. All isolates were characterized by spa typing. We collected 1,124 MRSA isolates from adults and 159 from children. Annual Orange County population estimates of MRSA inpatient clinical cultures were 119/100,000 adults and 22/100,000 children. spa types t008, t242, and t002 accounted for 83% of all isolates. The distribution of these three spa types among adults was significantly different from that among children ( 2 ‫؍‬ 52.29; P < 0.001). Forty-one percent of adult isolates were of t008 (USA300), compared to 69% of pediatric isolates. In multivariate analyses, specimens from pediatric patients, wounds, non-intensive care unit (ICU) wards, and hospitals with a high proportion of Medicaid-insured patients were significantly associated with the detection of t008 strains. While community-and health care-associated MRSA reservoirs have begun to merge, significant differences remain in pediatric and adult patient populations. Community-associated MRSA spa type t008 is significantly more common in pediatric patients.

Patient sharing and population genetic structure of methicillin-resistant Staphylococcus aureus

“…Nonetheless, because none of these variables perfectly captures similarities in patient populations, it is possible that the association between patient sharing and genetic similarity of MRSA remains biased by some of these factors. Specific spa types associated with pediatric and adult patients in this population have been described recently (29). Fifth, although the spa genotyping method used in the current study is widely used as a fast and reliable genotyping technique for S. aureus, we might obtain more meaningful results if we used higher-resolution typing systems.…”

Incidence and antibiotic susceptibility of MRSA infections in a Saudi Arabian Hospital: a 10-year surveillance study

“…One reason for this could be that older individuals are more likely to visit healthcare facilities or live in long-term care facilities. However, a prospective cohort study, collecting all clinical MRSA isolates from 30 of 31 hospitals in California in order to characterize differences in pediatric and adult MRSA strains, showed significantly more genetic diversity among adult MRSA isolates than among pediatric isolates [30]. This could be due to different degrees of contact; for example, adults may have more diverse MRSA encounters (travel, work, social venues, and health care facilities).…”

“…This could be due to different degrees of contact; for example, adults may have more diverse MRSA encounters (travel, work, social venues, and health care facilities). In contrast, children are often healthier and are more likely to encounter MRSA in the community through exposure to high-density environments such as schools and day care [30].…”

Trends in Invasive Methicillin-Resistant Staphylococcus aureus Infections

“…21 USA300 has emerged as a cause of health care-associated infections causing NICU outbreaks, and in at least 1 region of the country USA300 has been reported as the most prevalent strain causing health careassociated BSIs. [21][22][23][24] It is still unclear, however, whether USA300 is adding to the current disease burden or replacing USA100 as the main cause of MRSA infections in the children.…”