TY - JOUR
T1 - Bacterial content and characterization of antibiotic resistant Staphylococcus aureus in Danish sushi products and association with food inspector rankings
AU - Li, Heng
AU - Stegger, Marc
AU - Dalsgaard, Anders
AU - Leisner, Jørgen J.
PY - 2019
Y1 - 2019
N2 - This study examined the prevalence and phenotypic and genotypic antibiotic resistance patterns of Staphylococcus aureus in sushi from 20 Danish outlets. Microbial quality of sushi products and food inspector ranking of outlets were assessed and results for thirteen of the outlets were compared with findings from a previous study in 2012. Inspector rankings were similar in the two studies. The mesophilic aerobic counts were slightly lower (p = 0.0296) in 2017 than in 2012 with average values of the 13 shops of 5.2 log CFU/g and 5.7 log CFU/g, respectively. In both studies E. coli was only found in the products from outlets that did not have consistently superior rankings. On the other hand prevalence and average counts of Staphylococcus spp. were slightly higher in 2017 (p = 0.0286) but no methicillin-resistant S. aureus (MRSA) were observed in the present study. Methicillin-sensitive S. aureus (MSSA) were, however, isolated from 18.7% of sushi products with an average count below 2 log CFU/g. Based on spa and multilocus sequence typing (MLST), isolates belonged to clonal complex CC7 (t2016), CC20 (t7836), CC45 (t065, t127, t362), CC88 (t1998) and CC398 (t164, t331, t1451). The Panton-Valentine leukocidin (PVL)-encoding gene lukF was detected only in isolates of the t065 spa-type whereas the scn gene from the ΦSa3 prophage was detected in 76.5% of the isolates, supporting that the majority of isolates were of likely human origin. Thirty-six isolates (70.6%) were resistant to at least one of the antibiotic compounds tested. Antibiotic resistance genes that confer resistance to β-lactams (blaZ) and macrolides (ermC) were detected in 33.3% and 9.8% of isolates, respectively. The tet(K) gene that encode tetracycline resistance was only found in a t7836 strain. Overall, this study indicates that S. aureus in sushi products in Denmark do not represent a major food safety hazard due to, firstly, the low temperature and limited time of storage of product may prevent significant growth and production of toxic levels of enterotoxin of this species. Secondly, the S. aureus isolates obtained did not include MRSA variants and none of them encoded PVL that constitute one of the virulence factors in pathogenesis. Several MSSA isolates contained however genes encoding antibiotic resistance, which emphasize the potential role of foods as vehicles for transmission of such variants.
AB - This study examined the prevalence and phenotypic and genotypic antibiotic resistance patterns of Staphylococcus aureus in sushi from 20 Danish outlets. Microbial quality of sushi products and food inspector ranking of outlets were assessed and results for thirteen of the outlets were compared with findings from a previous study in 2012. Inspector rankings were similar in the two studies. The mesophilic aerobic counts were slightly lower (p = 0.0296) in 2017 than in 2012 with average values of the 13 shops of 5.2 log CFU/g and 5.7 log CFU/g, respectively. In both studies E. coli was only found in the products from outlets that did not have consistently superior rankings. On the other hand prevalence and average counts of Staphylococcus spp. were slightly higher in 2017 (p = 0.0286) but no methicillin-resistant S. aureus (MRSA) were observed in the present study. Methicillin-sensitive S. aureus (MSSA) were, however, isolated from 18.7% of sushi products with an average count below 2 log CFU/g. Based on spa and multilocus sequence typing (MLST), isolates belonged to clonal complex CC7 (t2016), CC20 (t7836), CC45 (t065, t127, t362), CC88 (t1998) and CC398 (t164, t331, t1451). The Panton-Valentine leukocidin (PVL)-encoding gene lukF was detected only in isolates of the t065 spa-type whereas the scn gene from the ΦSa3 prophage was detected in 76.5% of the isolates, supporting that the majority of isolates were of likely human origin. Thirty-six isolates (70.6%) were resistant to at least one of the antibiotic compounds tested. Antibiotic resistance genes that confer resistance to β-lactams (blaZ) and macrolides (ermC) were detected in 33.3% and 9.8% of isolates, respectively. The tet(K) gene that encode tetracycline resistance was only found in a t7836 strain. Overall, this study indicates that S. aureus in sushi products in Denmark do not represent a major food safety hazard due to, firstly, the low temperature and limited time of storage of product may prevent significant growth and production of toxic levels of enterotoxin of this species. Secondly, the S. aureus isolates obtained did not include MRSA variants and none of them encoded PVL that constitute one of the virulence factors in pathogenesis. Several MSSA isolates contained however genes encoding antibiotic resistance, which emphasize the potential role of foods as vehicles for transmission of such variants.
KW - Antibiotic resistance
KW - CC types
KW - Microbiological quality
KW - MRSA
KW - MSSA
KW - Raw fish
KW - Smiley ranking
KW - spa types
KW - Staphylococcus spp.
U2 - 10.1016/j.ijfoodmicro.2019.108244
DO - 10.1016/j.ijfoodmicro.2019.108244
M3 - Journal article
C2 - 31202150
AN - SCOPUS:85067055613
SN - 0168-1605
VL - 305
JO - International Journal of Food Microbiology
JF - International Journal of Food Microbiology
M1 - 108244
ER -