Abstract
BackgroundRecent reports highlight the incursion of community-associated MRSA within healthcare settings. However, knowledge of this phenomenon remains limited in Latin America. The aim of this study was to evaluate the molecular epidemiology of MRSA in three tertiary-care hospitals in Medellín, Colombia.MethodsAn observational cross-sectional study was conducted from 2008–2010. MRSA infections were classified as either community-associated (CA-MRSA) or healthcare-associated (HA-MRSA), with HA-MRSA further classified as hospital-onset (HAHO-MRSA) or community-onset (HACO-MRSA) according to standard epidemiological definitions established by the U.S. Centers for Disease Control and Prevention (CDC). Genotypic analysis included SCCmec typing, spa typing, PFGE and MLST.ResultsOut of 538 total MRSA isolates, 68 (12.6%) were defined as CA-MRSA, 243 (45.2%) as HACO-MRSA and 227 (42.2%) as HAHO-MRSA. The majority harbored SCCmec type IVc (306, 58.7%), followed by SCCmec type I (174, 33.4%). The prevalence of type IVc among CA-, HACO- and HAHO-MRSA isolates was 92.4%, 65.1% and 43.6%, respectively. From 2008 to 2010, the prevalence of type IVc-bearing strains increased significantly, from 50.0% to 68.2% (p = 0.004). Strains harboring SCCmec IVc were mainly associated with spa types t1610, t008 and t024 (MLST clonal complex 8), while PFGE confirmed that the t008 and t1610 strains were closely related to the USA300-0114 CA-MRSA clone. Notably, strains belonging to these three spa types exhibited high levels of tetracycline resistance (45.9%).ConclusionCC8 MRSA strains harboring SCCmec type IVc are becoming predominant in Medellín hospitals, displacing previously reported CC5 HA-MRSA clones. Based on shared characteristics including SCCmec IVc, absence of the ACME element and tetracycline resistance, the USA300-related isolates in this study are most likely related to USA300-LV, the recently-described ‘Latin American variant’ of USA300.
Highlights
Since its emergence in 1961, methicillin-resistant Staphylococcus aureus (MRSA) has traditionally been considered a nosocomial pathogen
Healthcare-associated MRSA (HA-MRSA) infections generally occur in individuals with predisposing risk factors such as surgery or presence of indwelling medical devices, whereas CAMRSA infections typically occur in otherwise healthy individuals who do not exhibit such risk factors [2]
The community-associated MRSA (CA-MRSA) clone USA300 (ST8-MRSA-IV) has recently been associated with nosocomial infections in Latin America [5,12,19]. Most of the latter isolates belong to a distinct Latin American variant of USA300 recently dubbed ‘‘USA300LV’’, which is characterized by carriage of SCCmec IVc, absence of the arginine catabolic mobile element (ACME) and high prevalence of tetracycline resistance [12,20]
Summary
Since its emergence in 1961, methicillin-resistant Staphylococcus aureus (MRSA) has traditionally been considered a nosocomial pathogen. The CA-MRSA clone USA300 (ST8-MRSA-IV) has recently been associated with nosocomial infections in Latin America [5,12,19] Most of the latter isolates belong to a distinct Latin American variant of USA300 recently dubbed ‘‘USA300LV’’, which is characterized by carriage of SCCmec IVc, absence of the arginine catabolic mobile element (ACME) and high prevalence of tetracycline resistance [12,20]. The aim of this study was to evaluate the molecular epidemiology of MRSA strains isolated from patients between 2008–2010 in three tertiary-care hospitals in Medellın, the second largest city in Colombia. Recent reports highlight the incursion of community-associated MRSA within healthcare settings Knowledge of this phenomenon remains limited in Latin America. The aim of this study was to evaluate the molecular epidemiology of MRSA in three tertiary-care hospitals in Medellın, Colombia
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