title: 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.
abstract: 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 (VTor non-VT), which were further divided into VT(n=22) and non-VT(n=16). The most common spa type in VTand non-VTisolates 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 (VT, n=8; non-VT, n=9). The most common spa-MLST types of OS-MRSA in VTand non-VTwere 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.
authors.affiliation: Department of Laboratory Medicine, China Medical University Hospital, Taichung, Taiwan; Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan; Department of Nursing, Hungkuang University, Taichung, Taiwan; Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.
authors.forename: Cheng-Mao
authors.initials: CM
authors.lastname: Ho
authors.affiliation: Department of Laboratory Medicine, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.
authors.forename: Chien-Yu
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Mao-Wang
authors.initials: MW
authors.lastname: Ho
authors.affiliation: Department of Infectious Diseases, Children's Hospital, China Medical University Hospital, China Medical University, Taichung, Taiwan.
authors.forename: Hsiao-Chuan
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Chao-Jung
authors.initials: CJ
authors.lastname: Chen
authors.affiliation: Department of Laboratory Medicine, Chang-Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Kweu-Shan, Taoyuan, Taiwan.
authors.forename: Lee-Chung
authors.initials: LC
authors.lastname: Lin
authors.affiliation: Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan; Department of Laboratory Medicine, Chang-Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Kweu-Shan, Taoyuan, Taiwan. Electronic address: janglu45@gmail.com.
authors.forename: Jang-Jih
authors.initials: JJ
authors.lastname: Lu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002440:Cefoxitin / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010068:Oxacillin / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013624:Taiwan; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D002440:Cefoxitin; D010068:Oxacillin
keywords: Cefoxitin; MLST; OS-MRSA; Oxacillin; Staphylococcus aureus; mecA; mecC; spa