Molecular epidemiology of hospital-onset methicillin-resistant Staphylococcus aureus infections in Southern Chile

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen of public health importance. In Chile, the Cordobes/Chilean clone was the predominant healthcare-associated MRSA (HA-MRSA) clone in 1998. Since then, the molecular epidemiological surveillance of MRSA has not been performed in Southern Chile. We aimed to investigate the molecular epidemiology of HA-MRSA infections in Southern Chile to identify the MRSA clones involved, and their evolutionary relationships with epidemic international MRSA lineages. A total of 303 single inpatient isolates of S. aureus were collected in the Valdivia County Hospital (2007-2008), revealing 33% (100 MRSA/303) prevalence for HA-MRSA infections. The SCCmec types I and IV were identified in 97% and 3% of HA-MRSA, respectively. All isolates lacked the pvl genes. A random sample (n = 29) of all MRSA was studied by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), SCCmec subtyping, agr and spa typing, and virulence genes profiling. PFGE analysis revealed the predominance (89%, 26/29) of pulsotype A and three additional pulsotypes, designated H1, I33, and G1. Pulsotype A (ST5-SCCmecI-spa-t149) is clonally related to the Cordobes/Chilean clone. Pulsotype H1 (ST5-SCCmecIVNT-spa-t002) is genetically related to the Pediatric clone (ST5-SCCmecIV). Pulsotype I33 (ST5-SCCmecIVc-spa-t002) is clonally related by PFGE to the community-associated MRSA (CA-MRSA) clone spread in Argentina, I-ST5-IVa-PVL(+). The G1 pulsotype (ST8-SCCmecIVc-spa-t024) is clonally related to the epidemic USA300 CA-MRSA. Here, we demonstrate the stability of the Cordobes/Chilean clone over time as the major HA-MRSA clone in Southern Chile. The identification of two CA-MRSA clones might suggest that these clones have entered into the healthcare setting from the community. These results emphasize the importance of the local surveillance of MRSA infections in the community and hospital settings.

Genetic Relatedness and Diversity of Staphylococcus aureus from Different Reservoirs: Humans and Animals of Livestock, Poultry, Zoo, and Aquaculture

“…The high prevalence of cefoxitin and ciprofloxacin resistances in human strains ( Table 1 ) agrees with other Portuguese studies [ 22 ], as well as other countries [ 23 , 24 ]. On the contrary, countries like Gambia have much lower rates [ 25 ].…”

Phenotypic and Genotypic Characterization of Macrolide, Lincosamide and Streptogramin B Resistance among Clinical Methicillin-Resistant Staphylococcus aureus Isolates in Chile

“…The present study reports percentages of resistance to antibiotics in the MLS B group ≥90% in HA-MRSA. This finding agrees with the results of previous studies carried out with strains collected in Chile [ 10 , 19 ]. Besides, 20% of strains of CA-MRSA were resistant to MLS B group.…”

“…Our results are in agreement with previous reports about the predominance of SCC mec type I-ST5 in HA-MRSA in Chile with classic resistance profiles of the Chilean/Cordobes clone that has a marked presence in hospitals of our country [ 10 , 26 ], and isolates of type IV-ST8 in CA-MRSA in Latin America, related to the USA-300 clone [ 10 , 19 ]. On the other hand, the dichotomy regarding the presence of MLS B or MS B resistance among HA-MRSA isolates highlights compared with CA-MRSA (97% vs approximately 25%, reaching statistical significance, p < 0.005).…”

Antimicrobial Resistance and Molecular Analysis of Methicillin-ResistantStaphylococcus aureusCollected in a Spanish Hospital

“…These include tourists from Britain, where ST22-MRSA-IV and ST36-MRSA-II predominate in hospitals and the general community, 3 and South America, where ST5-MRSA-IV is most common in the community. 15 Tenerife is therefore highly exposed to MRSA carriers from all over the world. Similar observations have been made about the Balearic Islands, another touristic archipelago of Spain.…”