Epidemiology and staphylococcal cassette chromosome mec typing of methicillin-resistant Staphylococcus aureus isolates in Taiwan: A multicenter study

Background/Purpose: After community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was identified, new community-onset, healthcare-associated MRSA (HA-MRSA-CO) infections have been noticed as MRSA infection in patients with community-onset infection who have underlying conditions resulting in frequent exposure to the healthcare system. However, previous studies have not thoroughly investigated whether HA-MRSA-CO has characteristics resembling those of CA-MRSA or hospital-onset, healthcare-associated MRSA (HA-MRSA-HO) infection. Methods: A multicenter, retrospective study was conducted to analyze the clinical and microbiological data of patients with clinical isolates of MRSA from nine hospitals in Taiwan. Results: In total, 203 patients with MRSA isolates, including 27 patients with CA-MRSA (13.3%), 59 with HA-MRSA-CO (29.1%), and 117 with HA-MRSA-HO (57.6%), were studied. Compared to HA-MRSA-HO isolates, the CA-MRSA and HA-MRSA-CO isolates were associated with a higher proportion of skin and soft tissue infections (81.8% and 65.3% vs. 40.5%, p=. 0.001 and p=. 0.002) as well as lesser rate of resistance to ciprofloxacin (33.3% and 50.9% vs. 74.4%, p<. 0.001 and p=. 0.002), gentamicin (44.4% and 64.4% vs. 84.6%, p<. 0.001 and p=. 0.002), and trimethoprim/sulfamethoxazole (33.3% and 42.4% vs. 58.1%, p=. 0.02 and p=. 0.048), and a lower 30-day all-cause mortality rate (7.4% and 0% vs. 20.9%, p<. 0.001). Most of the CA-MRSA isolates were classified as staphylococcal cassette chromosome mec (SCC. mec) type VT (11/27, 40.7%), whereas most HA-MRSA-HO isolates were classified as SCC. mec type III (66/117, 56.4%). Conclusion: The CA-MRSA, HA-MRSA-CO, and HA-MRSA-HO clinical isolates significantly differed in their clinical presentations and molecular characteristics.