Methicillin-resistant Staphylococcus aureus isolates with SCCmec type V and spa types t437 or t1081 associated to discordant susceptibility results between oxacillin and cefoxitin, Central Taiwan

作者：Ho Cheng Mao; Lin Chien Yu; Ho Mao Wang; Lin Hsiao Chuan; Chen Chao Jung; Lin Lee Chung; Lu Jang Jih^*

来源：Diagnostic Microbiology and Infectious Disease, 2016, 86(4): 405-411.

DOI：10.1016/j.diagmicrobio.2016.08.025

• OS-MRSA
• mecA
• mecC
• Staphylococcus aureus
• Oxacillin
• Cefoxitin
• MLST
• spa

Staphylococcus aureus isolates with discordant susceptibility results between oxacillin and cefoxitin obtained using automated microbiology systems are infrequently observed. From April 2013 to December 2014, 1956 methicillin-resistant S. aureus (MRSA) and 1761 methicillin-susceptible S. aureus isolates were obtained from different patients. Forty isolates (1.1% and 2% in case of S. aureus and MRSA, respectively) with discordant susceptibility results (oxacillin susceptible and cefoxitin resistant) and carrying mecA gene were obtained. Except 2 SCCmec type IV isolates, 38 MRSA isolates were all SCCmec type V (V-T or non-V-T), which were further divided into V-T (n = 22) and non-V-T (n = 16,). The most common spa type in V-T and non-V-T isolates were t437 (n = 19) and t1081 (n = 13), respectively. Only 55% of patients received effective antimicrobial agents; 2 mortalities were not attributable to MRSA infection. Using standard agar dilution, 17 MRSA isolates (0.46% and 0.87% in case of S. aureus and MRSA, respectively) had oxacillin MIC in the susceptible ranges (oxacillin-susceptible MRSA [OS-MRSA]); all carried SCCmec type V (V-T, n = 8; non-V-T, n = 9). The most common spa-MLST types of OS-MRSA in V-T and non-V-T were t437-ST59 (n = 4) and t1081-ST45 (n = 7), respectively. Concomitant testing by both cefoxitin- and oxacillin-based methods is a practical strategy for OS-MRSA detection in the clinical laboratories. Continuous monitoring of OS-MRSA isolates is necessary to elucidate their impact in clinical infectious diseases.

• 出版日期2016-12
• 单位长春大学; 中国医科大学