| Objective:To investigate the contamination prevalence,antimicrobial susceptibility profiles and molecular characteristics of both Staphylococcus aureus(SA)and Staphylococcus epidermidis(SE)isolated from the objects'surface of environment of secondary schools in Guangzhou,China.Methods:A cross-sectional study was conducted to investigate the contamination prevalence of SA and SE of the environmental objects'surface from classrooms,toilets,stairs,corridors and gymnasiums/playgrounds of ten secondary schools.The standard microbiological assays and PCR assays were used for the isolation and identification,and disk-diffusion methods were applied for antimicrobial susceptibility testing of both SA and SE.The sea gene,seb gene,tst gene and hla gene of both SA and SE,as well as the SCCmec type in methicillin-resistant Staphylococcus aureus(MRSA)strains were screened by PCR assays.The ST types in SA was identified through multiculocus sequencing typing(MLST).Rates were used to describe the contamination and antimicrobial resistance.Andc~2 test/fisher'exact test,logistic regression analysis were applied to compare the contamination rates and antibiotic resistant rates between different place,types of staphylococci,as well as whether resistant to methicillin or not.The eBRUST V3 software and dendrogram was used for exploring the clonal relatedness and homologous relationships among different aureus.Results:The contamination prevalence of SA and SE:1830 samples of objects'surface were collected from environment of secondary schools.The contamination prevalence of SA was 7.54%(138/1830),in which MRSA1.86%(34/1830);SE 13.83%(253/1830)and in which methicillin-resistant Staphylococcus epidermidis(MRSE)5.68%(104/1830).The contamination rate from highest to lowest among different places was:classrooms(8.69%)>stairs(7.33%)>toilets(7.04%)>corridors(6.67%)>gymnasiums/playgrounds(4.00%)for SA and stairs(18.00%)>classrooms(15.95%)>corridors(15.33%)>toilets(10.00%)=gymnasiums/playgrounds(10.00%).Significant difference wasn't observed among different places for SA(c~2=4.66,P=0.324),but higher in classrooms than toilets for SE(c~2=9.89,P=0.002).SA was highest in electrical buttons(16.67%),while SE was highest in seats(19.38%).Besides,SA was highest in school J(17.49%),lowest in school A and F(2.19%),and SE was highest in school G(33.88%),lowest in school F(3.28%).The contamination rate of both SA(c~2=64.55,P<0.001)and SE(c~2=64.55,P<0.001)were significant different among different secondary schools.Moreover,there was no difference between urban and rural for SA(c~2=1.33,P=0.288),while higher in urban than rural for SE(c~2=60.66,P<0.001)in the contamination.Antimicrobial susceptibility testing:SA was mainly resist to penicillin(82.61%,114/138)and erythromycin(57.25%,79/138),and SE was mainly resist to erythromycin(71.15%,180/253)and penicillin(53.75%,136/253),both of which were lowest resistance to linezolid(0.00%and1.58%).When comparing with SE,the resistance rate of SA was higher in penicillin(OR=4.09,95%CI:2.47-6.77)andrifampicin(OR=2.22,95%CI:1.23-4.00),and lower in erythromycin(OR=0.54,95%CI:0.35-0.84)and trimethoprim-sulfamethoxazole(OR=0.12,95%CI:0.06-0.23).Likewise,the resistance was higher in penicillin(OR=5.18,95%CI:1.15-23.32)and rifampicin(OR=3.26,95%CI:1.35-7.90),while lower in trimethoprim-sulfamethoxazole(OR=0.16,95%CI:0.16-0.42)for MRSA to MRSE.Meanwhile,MRSA showed more serious resistance in five antibiotics(cefoxitin,clindamycin,erythromycin,trimethoprim-sulfamethoxazole,rifampicin)than methicillin-sensitive Staphylococcus aureus(MSSA),and MRSE showed higher resist rate of six antibiotics(cefoxitin,penicillin,erythromycin,trimethoprim-sulfamethoxazole,rifampicin and tetracycline)thanmethicillin-sensitiveStaphylococcusepidermidis(MSSE).The multidrug-resistant rate in MRSA(82.35%,28/34)and MRSE(77.66%,73/94)was higher than MSSA and MSSE,respectively.Virulence gene screening:The detection rate of four virulence genes from highest to lowest were:hla(82.61%)>sea(30.43%)>tst(16.67%)>seb(14.49%)for SA,and hla(1.58%)>seb(0.40%)>sea(0.00%)=tst(0.00%)for SE.The detection rate of four virulence genes were higher for SA than SE.Moreover,MRSA showed higher detection rate of tst gene than MSSA(OR=3.67,95%CI:1.44-9.36),and the similar detection rate between MRSE and MSSE.SCCmec typing of MRSA:The SCCmec type from highest rate to lowest rate were:thirteen isolates of IV type(38.24%,13/34),in which nine of IVa type(26.47%,9/34),one of IVc type(2.94%,1/34),one of IVd type(2.94%,1/34)and two of which untyping(5.88%,2/34);two of V type(5.88%,2/34);one(2.94%,1/34)for type I;one(2.94%,1/34)for type II;with seventeen of untyping and none of III or IVb was screened.MLST:A total of 25 ST types were investigated for SA isolated from environment of secondary school.There were 22 isolates of ST188(15.94%,22/138);12 isolates(8.70%,12/138)separately for ST72,ST7 and ST45;seven isolates(5.07%,7/138)for ST30;six isolates(4.35%,6/138)separately for ST 108 and ST338;four isolates(2.90%,4/138)separately for ST6,ST15 and ST1163;three isolates(2.17%,3/138)separately for ST5,ST217,ST398,ST1281 and ST2631,two isolates(1.45%,2/138)separately for ST 8 and ST59;and one(0.72%,1/138)separately for ST97?ST573?ST630?ST965,ST20,ST88,ST672 and ST944.The results conducted by eBRUST V3 showed that SA was mainly from the global CC5 clone type(36.96%,51/138),and MRSA was found clustered among different places and schools.Conclusions:The contamination prevalence of SA of objects'surface from environment of secondary schools is in a middle-lower level among similar researches,MRSA accounts for nearly twenty percent and shows more than75%of multi-drug resistance.The contamination prevalence of SE is higher than SA,while in a lower level among similar researches,MRSE accounts for nearly one quarterand shows more than 80%of multi-drug resistance.The SA has high detection rate of virulence gene.MRSA is mainly community associated.SA mainly belongs to CC5 clone type with ST188 as a major ST typing.Potential risks of toward contamination for MRSA exists among different places and schools. |
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