Heterogeneity of Molecular Characteristics among Staphylococcus argenteus Clinical Isolates (ST2250, ST2793, ST1223, and ST2198) in Northern Taiwan

Abstract

Staphylococcus argenteus is an emerging pathogen that is recognized as non-pigmented Staphylococcus aureus. However, the molecular characteristics of S. argenteus and its virulence factors have not been well studied. The present study analyzed 96 isolates of S. argenteus recovered from blood. Identification of S. argenteus was based on results of MALDI-TOF MS and lacking crtM gene. All 96 isolates were methicillin-susceptible. Multilocus sequence typing (MLST) revealed four sequence types: ST2250 (n = 72), ST2793 (n = 12), ST1223 (n = 10), and ST2198 (n = 2). All 72 ST2250 isolates harbored CRISPR loci with polymorphism of direct repeats and spacers, but no other STs carried CRISPR loci. To date, ST2793 isolates have rarely been reported in other countries. Collagen-binding adhesin gene (cna) and staphylococcal enterotoxin type C (sec) were detected in 12 (100%) and 8 (67%) ST2793 isolates, respectively. ST1223 has been reported as food poisoning pathogens, and enterotoxin gene clusters (egc) were detected in all 10 isolates, while seb gene was detected in three isolates. Two ST2198 isolates carried bone sialoprotein-binding protein gene (bbp), belonging to agr type IV. Our focus on the heterogeneity of molecular characterization in four ST types of S. argenteus revealed that S. argenteus had been isolated as early as 2000. Each ST type of S. argenteus harbors particular genetic markers that may contribute to their virulence.

Distribution of Virulence Factors and Resistance Determinants in Three Genotypes of Staphylococcus argenteus Clinical Isolates in Japan

“…It was notable in the present study that distribution of staphylococcal enterotoxin (SE)-like genes was distinctive depending on the three STs; seb , egc-2 , and selw in ST1223, sey and sel26-sel27 in ST2250, and the dominance of selx in ST2198. Similar findings regarding the correlation of ST and toxin genes have been reported previously for S. argenteus isolates in Japan [ 19 , 20 , 21 , 22 ], Taiwan [ 16 ] and Myanmar [ 15 ]. Our study on the prevalence of newer SE(-like) genes in CA-MRSA revealed lower detection rates of selz (5.6%) and sel26-sel27 (0%) [ 50 ].…”

“…In Japan, ST1223 and ST2250 S. argenteus have been reported in various types of infectious diseases, with ST1223 being mainly detected in food poisoning outbreaks [ 18 , 19 , 21 , 22 , 38 , 39 ]. While the predominance of ST2250 has been reported worldwide, ST1223 and ST2198 were less frequently detected in Asian countries [ 7 , 13 , 14 , 15 , 16 , 17 , 33 ]. In a recent study in Taiwan of blood isolates, ST1223 and ST2198 accounted for 11% and 2%, respectively [ 16 ].…”

“…While the predominance of ST2250 has been reported worldwide, ST1223 and ST2198 were less frequently detected in Asian countries [ 7 , 13 , 14 , 15 , 16 , 17 , 33 ]. In a recent study in Taiwan of blood isolates, ST1223 and ST2198 accounted for 11% and 2%, respectively [ 16 ]. Thus, our present and previous study [ 20 ] may indicate a distinct epidemiological feature of S. argenteus clones in northern Japan, i.e., relatively higher prevalence of ST1223 and ST2189.…”

“…Thereafter, various STs and CCs have been identified for S. argenteus , including CC1223, CC2198, CC2250, CC2596 and CC2854 [ 7 ], and more than 60 STs have been currently assigned under several clonal complexes. ST2250 is considered to be the dominant clone with widespread geographical distribution including Europe [ 8 , 9 , 10 , 11 , 12 ], Southeast Asia [ 13 , 14 , 15 , 16 ], China [ 17 ], and Japan [ 18 , 19 , 20 ], while ST1223, the lineage related to CC75, is less prevalent and has been described as the pathogen responsible for outbreaks of food poisoning in Japan [ 21 , 22 ] as well as colonizing isolates in Cambodia and the Amazonian forest [ 23 , 24 ].…”

“…A genomic study revealed that S. argenteus possesses most of the virulence factors of S. aureus , suggesting that S. argenteus has similar pathogenic potential to that of S. aureus [ 17 ]. Similarly, many reports have highlighted the pathogenicity and clinical importance of S. argenteus as an emerging infectious agent evidenced by the presence of various pathogenic genes [ 8 , 16 , 20 , 29 , 30 , 31 ].…”