北京市儿童A组链球菌分离株耐药特征及相关因素研究

目的 分析北京市儿童A组链球菌临床分离株对抗菌药物的耐药特点,为临床用药提供依据.方法 2011年5-7月从北京市36家医院收集儿童A组链球菌临床分离株.采用VITEK 2全自动生化分析仪测定上述菌株对10种抗菌药物的最低抑菌浓度(MIC),计算敏感率(S％)、中介率(I％)、耐药率(R％);用双纸片法(D实验)检测菌株对大环内酯类抗菌药物的耐药表型.结果 共采集咽拭子3315份,分离A组链球菌633株,咽拭子培养阳性率为19.1％.菌株对青霉素、氨苄西林、链阳霉素、利奈唑胺、替加环素和万古霉素的敏感率达100％,其次为左氧氟沙星(96.5％,611/633).对红霉素、四环素和克林霉素有较高的耐药率,依次为96.1％ (608/633)、93.7％(593/633)和79.3％ (502/633).共观察到9种耐药模式,以红霉素、克林霉素和四环素联合耐药为主(72.7％,460/633),其次为红霉素和四环素联合耐药(18.0％,114/633).608株对大环内酯类耐药的菌株中,83.2％(506/608)表现为固有型耐药(cLMS),诱导型耐药(iLMS)占16.0％(97/608),5株表现为主动外排型耐药.学龄儿童和菌株为郊区来源是A组链球菌对四环素耐药率的相关因素,OR值及其95％CI分别为2.43(1.16～5.09)和2.35(1.47～3.73);菌株为郊区来源是A组链球菌对克林霉素的耐药率的相关因素,OR值及其95％CI为0.48(0.25～0.92).结论 北京市儿童分离的A组链球菌对青霉素、氨苄西林全部敏感,对红霉素、四环素和克林霉素耐药水平较高,耐药表型以固有型耐药为主.研究对象职业和菌株为郊区来源是四环素耐药率相关因素,后者也是克林霉素耐药率相关因素.     

耐碳青霉烯类肺炎克雷伯菌耐消毒剂基因检测及同源性分析

目的 探讨武汉地区临床分离的耐碳青霉烯类肺炎克雷伯菌(CRKP)中耐消毒剂基因的携带状况及耐消毒剂基因携带菌株的同源性, 为有效预防和控制CRKP传播提供理论依据。 方法 收集2018—2019年武汉市3所三级医院临床住院患者分离的非重复性CRKP菌株, 采用最低抑菌浓度测定方法对药敏结果进行复核, 采用实时荧光定量聚合酶链反应(RT-PCR)检测耐消毒剂基因qacEΔ1、cepA, 采用脉冲场凝胶电泳(PFGE)对同时携带qacEΔ1和cepA基因的CRKP菌株进行同源性分析。 结果 共收集62株CRKP, 77.42%来源于重症监护病房(ICU), 40.32%来自痰标本。所有CRKP均为多重耐药菌, 对厄他培南、阿莫西林/克拉维酸、头孢唑林、头孢他啶、头孢曲松5种抗生素的耐药率均为100%, 对临床其他常见抗菌药物也呈现高度耐药。耐消毒剂基因检出率为95.16%(59/62), 其中qacEΔ1、cepA基因检出率分别为64.52%(40/62)、91.94%(57/62), 38株(61.29%)同时检出qacEΔ1和cepA。PFGE结果显示, 38株CRKP可分为A~K共11个型别, 以E型为主, 占42.11%(16株)。 结论 武汉地区CRKP菌株耐药形势严峻, 广泛携带耐消毒剂基因, 存在不同医院、不同科室间的克隆传播, 应加强流行病学监控, 合理使用消毒剂。     

广东省2013年副溶血弧菌暴发与散发菌株的病原学特征

目的 了解2013年广东省副溶血弧菌暴发与散发分离株的血清型别、抗菌药物耐药性、毒力基因携带情况以及分子分型特征.方法 对36株暴发分离株和43株散发分离株进行血清分型、药敏试验以及耐热直接溶血毒素基因(tdh)、耐热相关溶血毒素基因(trh)、GS-PCR和orf8基因的PCR检测,并进行脉冲场凝胶电泳(PFGE)分型.结果 36株暴发分离株全部为O3:K6血清型,43株散发分离株的优势血清型为O3:K6型(23株,53.49%).药敏检测结果显示,对氨苄西林(96.20%)和头孢噻吩(40.50%)的耐药率较高;对复方新诺明和氯霉素则高度敏感,敏感性均为100%.多重耐药分析显示,83.33%(30/36)的暴发分离株同时耐受≥3种抗菌药,37.21%(16/43)的散发分离株同时耐受≥3种抗菌药物.毒力基因PCR检测显示,36株暴发分离株均为tdh⁺tdh^-型菌株.86.05%(37/43)的散发分离株为tdh⁺tdh^-型菌株,11.63%(5/43)为tdh^-tdh⁺型菌株,仅1株为tdh⁺tdh⁺型菌株.暴发分离株全部携带GS-PCR和/或orf8基因,51.16%(22/43)的散发分离株携带GS-PCR和/或orf8基因.PFGE显示,79株副溶血弧菌经NotⅠ酶切后的PFGE图谱可分为3个聚类,32种PFGE型别,相似值为59.8%～100.0%.暴发菌株聚集在同一个聚类中,散发菌株散布在各个聚类中.结论 2013年广东省副溶血弧菌优势血清型为O3:K6型,菌株对多数抗菌药物仍然比较敏感,但存在多重耐药现象,多数菌株携带tdh基因,大部分O3:K6型菌株携带GS-PCR和/或orf8基因;PFGE结果提示广东省副溶血弧菌存在遗传多样性.     

大肠埃希菌临床菌株优势β-内酰胺酶基因型及其诱导表达与抑制的研究

目的 了解浙江地区大肠埃希菌临床菌株优势β-内酰胺酶基因型及其携带模式、β-内酰胺类抗生素诱导β-内酰胺酶基因表达及组氨酸激酶抑制剂氯氰碘柳胺(CLO)抑制其表达的作用。方法 采用微量稀释法和E-test检测大肠埃希菌临床菌株对β-内酰胺类抗生素耐药率和最低抑菌浓度(MIC)。采用PCR及其产物测序法检测大肠埃希菌耐药菌株β-内酰胺酶基因型及携带模式。采用实时荧光定量RT-PCR和β-内酰胺酶确证试验分别检测1/4 MIC头孢噻肟或青霉素及CLO对大肠埃希菌耐药菌株β-内酰胺酶基因转录和表达的影响。结果 浙江地区61.7%(285/462)大肠埃希菌对青霉素、氨苄青霉素、头孢西丁、头孢噻肟和头孢他啶耐药。285株耐药菌株中, TEM和CTX-M基因检出率(83.2%和75.1%)显著高于KPC、SHV和OXA基因(1.4%～10.2%)(P<0.01), 两种以上β-内酰胺酶基因携带率(68.8%)显著高于单基因(31.2%)(P<0.01), 其中61.4%菌株携带TEM+CTX-M基因(P<0.01)。除KPC基因外, 1/4 MIC头孢噻肟和青霉素能诱导89株β-内酰胺酶单基因菌株TEM、CTX-M、SHV和OXA mRNA水平迅速升高(P<0.01), 但可被50～500 μg/ml CLO所抑制(P<0.01)。100 μg/ml CLO预处理后, 82.8%～85.6%耐药菌株对上述抗生素敏感(P<0.01), β-内酰胺酶检出率也从95.1%下降至16.1%(P<0.01)。结论 TEM和CTX-M是浙江地区大肠埃希菌临床菌株优势β-内酰胺酶基因型, 并以TEM-1+CTX-M为优势携带模式。低浓度头孢噻肟和青霉素可经细菌二元信号系统上调β-内酰胺酶基因表达, 但可被组氨酸激酶抑制剂CLO所抑制。     

某院耐亚胺培南鲍曼不动杆菌耐药基因及临床特征

目的 分析某院临床分离的耐亚胺培南鲍曼不动杆菌（IRAB）耐药基因携带情况，为医院感染防控和指导临床治疗提供实验室依据。方法 采用聚合酶链反应（PCR）方法检测该院临床分离的26株IRAB碳青霉烯类耐药基因（blaIMP、blaKPC、blaNDM-1、blaOXA-23、blaOXA-50、blaOXA-51、blaOXA-58）、氨基糖苷类耐药基因［ant（3"）-Ⅰ、aac（6''）-Ⅰ、armA］和消毒剂耐药基因qacE△1携带情况。结果 26株IRAB均携带碳青霉烯酶基因OXA-23和OXA-51，检出率为100%，未检出其他碳青霉烯类耐药基因。氨基糖苷类耐药基因ant（3"）-Ⅰ、aac（6''）-Ⅰ和armA检出率均为96.15%，消毒剂耐药基因qacE△1基因携带率为65.38%。临床分离IRAB菌株92.31%来源于患者的痰液。结论 该院临床分离IRAB多数携带相同的碳青霉烯类耐药基因和氨基糖苷类耐药基因，需加强医院感染防控措施。     

多重耐药肺炎克雷伯菌发现一组gyrA,parC,qnrS基因新变异型

目的研究多重耐药肺炎克雷伯菌(MDR-KPN)对喳诺酮类药物的耐药机制。方法收集2008年8月至2010年5月浙江省杭州市和湖州市6所医院共47株MDR-KPN,采用聚合酶链反应((PCR)及序列分析方法分析喳诺酮类药物作用靶位编码基因gyrA,parC和可移动遗传元件介导的喳诺酮类耐药基因[qnrA,qnrB,qnrS,aac(6'')-I b-cr, qepA ]。结果47株MDR-KPN中检出43株(91.5% gyrA突变、40株(85.1 % ) parC突变、3株(6.4% ) qnrB2,1株(2.1%)qnrB4,8株(17.0%)qnrS1,5株(10.6% ) qnrS4, 2株(4.3% ) aac (6'')-I b-cr,发现5株gyrA基因新的变异型( GenBank登录:JN811952,JN811953,JN811954,JN811955,JN811956),5株parC基因新的变异型(GenBank登录:JN817432,JN817433,IN817434,JN817435,JN817436),qnrS4为首次发现的qnrS变异型(GenBank登录号:JN836269)。结论本组菌株喳诺酮类药物耐药主要与gyrA和parC基因的喳诺酮耐药决定区(QRDR )有义突变相关,部分菌株可检出qnrB2,qnrB4,qnrS1,qnrS4,aac(6'')-I b-cr等可移动遗传元件介导的哇诺酮类耐药基因。检出qnrS4为国内外首次报道。     

T6SS阳性CRKP临床感染特征及毒力基因分析

目的 分析T6SS阳性耐碳青霉烯类肺炎克雷伯菌(CRKP)临床感染特征, 以及其耐药、毒力基因检出率和生物膜形成能力, 为临床防控CRKP感染提供参考数据。 方法 收集2019年1月—2022年12月安徽某三甲医院临床分离的CRKP菌株及患者资料, PCR法检测T6SS基因、毒力基因、耐药基因和分子分型, 96孔板结晶紫染色法检测生物膜形成能力。 结果 共纳入160株CRKP。标本来源以痰(46.9%)和血(26.3%)为主。CRKP菌株呈现多重耐药表型, 以携带bla_KPC(80.6%)为主, 其次为bla_NDM(17.5%)。根据是否携带T6SS将CRKP分为T6SS阳性组(129株, 80.6%)和T6SS阴性组(31株, 19.4%)。T6SS阳性组患者患慢性肺部疾病和心脏疾病比例高于T6SS阴性组(P < 0.05), 且预后较阴性组差(P < 0.05)。T6SS阳性组中, iucA、mrkD、rmpA2、peg344、wabG、fimH检出率均高于T6SS阴性组(均P < 0.05)。CRKP中以ST11型(68.8%)为主, 其中K64-ST11型占比70.9%, K47-ST11型占比25.5%。T6SS阳性组ST11型和K64-ST11型CRKP占比均高于T6SS阴性组(均P < 0.05)。T6SS阳性组CRKP生物膜形成能力强于T6SS阴性组(P < 0.001)。两组除bla_OXA-48基因外, 在携带其他碳青霉烯类耐药基因和抗菌药物耐药率方面差异无统计学意义。 结论 该地区CRKP呈现多重耐药, CRKP菌株T6SS检出率高, T6SS阳性CRKP毒力基因检出率更高, 且生物膜形成能力更强。     

广东省2014年食源性副溶血弧菌病原学特征分析

目的 了解2014年广东省食源性副溶血弧菌分离株的血清型别、抗生素敏感性、毒力基因携带情况以及分子分型特征。方法 对60株副溶血弧菌分离株进行血清分型、抗生素敏感性试验及检测耐热直接溶血素基因(tdh)和耐热相关溶血素基因(trh),并进行脉冲场凝胶电泳(PFGE)和多位点序列(MLST)分型。结果 60株分离株可分为13个血清型,主要型别为O3:K6、O4:K8、O1:K36和O4:KUT;对氨苄西林、磺胺复合物和头孢噻吩的耐药率分别为100.0%、43.3%和28.3%,有56.7%(34/60)的菌株对2类及以上抗生素同时耐药,2株菌对3类抗生素同时耐受。毒力基因PCR检测发现,有63.3%(38/60)的分离株为tdh⁺trh^-菌株,仅1株为tdh⁺trh+菌株。分子分型显示,经NotⅠ酶消化后,60株副溶血弧菌可产生48个PFGE谱型,可分为3个聚类(Cluster A、B和C)。其中Cluster B的菌株主要分离自食源性疾病监测中心散发病例,血清型以O3:K6为主,PFGE谱型的相似度在62.6%～100.0%;Cluster C主要是由4株O4:K8型菌株组成,谱型相似度为56.7%～62.5%。60株菌MLST分型可分为26个ST型,其中33株菌为ST-3型,主要是O3:K6和O1:K36菌株;4株O4:K8菌株聚集成另一个不同于ST-3型的相对优势的菌群。结论 2014年广东省副溶血弧菌菌型多样性可能是疾病高发的原因之一,O4:K8型菌株的分子特征与其他优势血清型别明显不同,应高度警惕该型菌株引起暴发的可能。     

福建省结核分枝杆菌多位点可变数目串联重复序列基因分型研究

目的 了解福建省结核分枝杆菌的多位点可变数目串联重复序列基因分型(MLVA)的特征.方法 选择15个可变数目串联重复位点(VNTR),检测福建省30个耐药监测点临床分离的结核菌株,结果使用BioNumerics (Version 4.5)软件进行聚类分析.结果 313株结核菌被分为9个基因群(Ⅰ～Ⅸ),分别包含220、9、48、2、1、3、10、10、10株菌,以Ⅰ群为主(70.3％,220/313);Ⅰ群菌株异烟肼、链霉素、乙胺丁醇和耐多药的耐药率与其他基因群的差异无统计学意义(P＞0.05),但利福平(RFP)耐药率为33.2％(73/220),明显高于其他群菌株RFP的耐药率20.4％(19/93),差异有统计学意义(P＜0.05).结论 福建省结核分枝杆菌菌株存在明显的基因多态性,以Ⅰ群菌株为主,并与RFP耐药性具有相关性,应加强此类菌株流行的监测.     

结核分枝杆菌对环丝氨酸耐药分子特征的初步研究

目的 探讨结核分枝杆菌对环丝氨酸耐药性与alrA、ddlA和cycA基因突变的关系,分析环丝氨酸耐药与基因型的关联性。方法 从菌株库中选取145株临床分离株,采用比例法测定菌株对环丝氨酸耐药表型、微孔板刃天青显色法测定最小抑菌浓度,PCR扩增、DNA直接测序法测定目的基因全长,与标准菌株H37Rv比对。间隔区寡核苷酸基因分型（spoligotyping）进行菌株基因型鉴定,分析耐药表型与基因型的关系,采用χ²检验分析差异有无统计学意义。结果 145株临床分离株中,环丝氨酸耐药菌株为24株,敏感株为121株。24株耐药菌株中,3株（12.5%）发生cycA非同义突变,涉及的密码子为188位、318位和508位,1株（4.2%）发生alrA非同义突变,涉及密码子为261位。敏感菌株的目的基因中仅检出同义突变。药敏试验证实,突变株的最小抑菌浓度均有不同程度的升高。北京基因型为88株,环丝氨酸耐药率为20.5%（18/88）,非北京基因型为57株,环丝氨酸耐药率为10.5%（6/57）,两者耐药率差异无统计学意义（χ²=2.47,P>0.05）。结论 alrA和cycA单核苷酸非同义基因突变可能是环丝氨酸耐药的机制之一。尚不能确定北京基因型或非北京基因型菌株与环丝氨酸耐药有相关性。     

Staphylococcus aureus clfB and spa alleles of the repeat regions are segregated into major phylogenetic lineages

To reliably differentiate among Staphylococcus aureus isolates we recently developed the Double Locus Sequence Typing (DLST) based on the analysis of partial sequences of clfB and spa genes. This method is highly discriminatory and gives unambiguous definition of types. The highly clonal population structure of S. aureus suggests that isolates with identical clfB or spa alleles belong to the same clonal complex (CC) defined by Multi-Locus Sequence Typing (MLST). To test this hypothesis as well as to investigate putative intra-CC genetic structure, we analyzed a total of 289 isolates (186 MSSA and 103 MRSA) with DLST-, spa- and MLST-typing.Among the 289 strains, 242 were clustered into 7 major MLST CCs, 40 into minor CCs and 7 were not grouped into CCs. A total of 205 DLST- and 129 spa-types were observed. With one exception, all DLST-clfB, DLST-spa and spa-type alleles were segregated into CCs. DLST-types sharing an identical allele (clfB or spa) were clustered using eBURST. Except for one strain, all isolates from each DLST cluster belonged to the same CC. However, using both DLST- and spa-typing we were not able to disclose a clear intra-CC structure. Nevertheless, the high diversity of these loci confirmed that they are good markers for local epidemiological investigations.     

Methicillin resistant Staphylococcus aureus (MRSA) isolated in Saudi Arabia: epidemiology and antimicrobial resistance patterns

Methicillin resistant Staphylococcus aureus (MRSA) comprised about 7·5% per annum of all S. aureus isolated in a general hospital in Jeddah, Saudi Arabia during the 3 year period 1990–1992. Most isolates were from wound sites (71%). Resistance to gentamicin (83%) and tetracycline (93%) was frequently observed whilst resistance to ciprofloxacin (1%) and rifampicin (6%) was uncommon. Low levels of mupirocin resistance (MIC 8 mg 1⁻¹), were detected in 3% of all MRSA isolates.     

Epidemiologic study of Staphylococcus strains isolated from clinical material in 24 Italian Hospitals

A nationwide epidemiologic study of clinical Staphylococcus isolates was performed in Italy by 24 operative units distributed throughout the country. A total of 7,017 Staphylococcus strains were examined according to a standard protocol. Three species of acknowledged importance in human infections (namely S. aureus, S. epidermidis, and S. saprophyticus) were identified singly, whereas the other staphylococci were considered as a whole and designated Staphylococcus spp. S. aureus totalled 53% of total isolates and was reported by most operative units as the predominant species among isolates both from various inpatient departments and from outpatients. S. saprophyticus was twofold more frequent among isolates from out- than from inpatients. Susceptibility to methicillin varied considerably from hospital to hospital, but a general tendency toward an increasing spread of resistance was noted. The overall incidence of methicillin resistance (29%) resulted from' a wide. range of values generally higher in isolates from inpatients (35°0) than from outpatients (21%). Particularly high percentages of resistance (45%) were recorded in isolates from intensive care departments. Susceptibility testing to four additional -lactams (cefoxitin, cefuroxime, cefotaxime, and piperacillin) and to four aminoglycosides (gentamicin, tobramycin, amikacin, and netilmicin) indicated that antibiotic resistance was widespread and in all species more frequent among methicillin-resistant than among methicillin-sensitive staphylococci. Netilmicm proved more active than the other antibiotics tested; its greater activity was most evident against methicillin-resistant strains. Coagulase-negative staphylococci were more resistant than S. aureus to methicillin and most of the other antibiotics, suggesting their increasing involvement in human infections.Corresponding author.     

马鞍山地区耐甲氧西林金黄色葡萄球菌的分子特征研究

目的 了解马鞍山地区耐甲氧西林金黄色葡萄球菌(金葡菌)(MRSA)肠毒素、溶血素分布情况、菌株克隆群关系及其耐药性。方法 采用全自动酶联荧光免疫系统和PCR技术分别检测肠毒素和溶血素基因分布;选择金葡菌的7个管家基因作为目的基因,对34株MRSA和3株甲氧西林敏感金葡菌(MSSA)进行多位点序列分型(MLST),然后与网上数据库比对,获得序列型(ST),根据eBURST的ST进行亲缘性分析;采用琼脂稀释法检测MRSA对12种抗生素的耐药情况。结果 210株金葡菌肠毒素阳性率为50.9%,溶血素基因携带率为97.1%,其中51株MRSA全部含有溶血素基因。34株MRSA有10个ST,以ST239为主(47.1%,16/34),其次为ST5(17.6%,6/34);3株MSSA的ST为ST188、ST1281和ST7。17株患者来源菌株分为6个ST,以ST239为主(35.3%,6/17),其次为ST5(29.4%,5/17);20株食品来源菌株有9个ST别,以ST239为主(45.0%,9/20),其次为ST7(15.0%,3/20)。ST585、ST630以及ST239的亲缘关系较近,其他ST之间亲缘关系较远。除万古霉素外,所有菌株对10种抗生素有不同程度的耐药。结论 金葡菌溶血素普遍存在;ST239为马鞍山地区MRSA的主要优势菌株,各ST间亲缘关系较远。     

上海市浦东新区食源性小肠结肠炎耶尔森菌耐药及分子流行病学特征

目的 了解上海市浦东新区食源性小肠结肠炎耶尔森菌耐药及分子流行病学特征。方法 2012-2016年主动、定点采集上海市浦东新区4类流通生鲜食品,使用冷增菌方法分离小肠结肠炎耶尔森菌,并分析菌株生物型、血清型、毒力基因型、耐药性和PFGE分子型别。结果 共采集食品3 900份（禽类590份、畜类1 074份、水产品1 488份、蔬菜748份）,其中111份（2.8%）检出小肠结肠炎耶尔森菌。禽类制品（5.3%,31/590）和畜类制品（4.5%,48/1 074）的检出率高于水产品（1.6%,24/1 488）和蔬菜制品（1.1%,8/748）。分离株以生物1A型（95.5%）和O：8血清型（42.3%）为主,且分离数与年总分离数呈正相关。所有菌株均缺失4种（ail、ystA、yadA和virF）产毒株标记的毒力基因,76株（68.5%）ystB基因阳性（其中35株属于1A/O：8/ystB）。分离株对氨苄西林（74.8%）和阿莫西林/克拉维酸（70.3%）的耐药率最高,对头孢西丁不敏感率超过50.0%;未发现三代头孢菌素或氟喹诺酮类抗菌药物耐药株,38.7%（43/111）的菌株为多重耐药。O：8和O：5血清型菌株分别存在44和18种PFGE分子型别。结论 上海市浦东新区食源性小肠结肠炎耶尔森菌暴露风险以禽类制品和畜类制品为主,优势菌型为1A/O：8/ystB,虽无典型产毒株特征但仍有潜在致病力。菌株耐药率处于较低水平但存在多重耐药株,PFGE分子型别提示菌株呈高度遗传多样性。     

The evolution of Staphylococcus aureus

A broad variety of infections, ranging from minor infections of the skin to post-operative wound infections can be caused by Staphylococcus aureus. The adaptive power of S. aureus to antibiotics leaded, in the early 1960s, to the emergence of methicillin-resistant S. aureus (MRSA). The cause of resistance to methicillin and all other β-lactam antibiotics is the mecA gene, which is situated on a mobile genetic element, the staphylococcal cassette chromosome mec (SCCmec). Seven major variants of SCCmec, type I to VII, are distinguished. The most important techniques used to investigate the molecular epidemiology of S. aureus are pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), S. aureus protein A (spa) typing and SCCmec typing (only for MRSA). These techniques have been used to study the evolution of the MRSA clones that have emerged since the early 1960s, and to study their subsequent worldwide dissemination. The early MRSA clones were hospital-associated (HA-MRSA). However, from the late 1990s, community-associated MRSA (CA-MRSA) clones emerged worldwide. CA-MRSA harbors SCCmec type IV, V or VII, the majority belong to other S. aureus lineages compared to HA-MRSA, and CA-MRSA is often associated with the presence of the toxin Panton-Valentine leukocidin (PVL). However, during recent years, the distinction between HA-MRSA and CA-MRSA has started to disappear, and CA-MRSA is now endemic in many US hospitals. MRSA probably originated trough the transfer of SCCmec into a limited number of methicillin-sensitive S. aureus (MSSA) lineages. This review describes the latest observations about the structure of SCCmec, the techniques used to study the molecular epidemiology and evolution of S. aureus as well as some challenges that researchers face in the future.     

Global distribution and diversity of ovine-associated Staphylococcus aureus

Staphylococcus aureus is an important pathogen of many species, including sheep, and impacts on both human and animal health, animal welfare, and farm productivity. Here we present the widest global diversity study of ovine-associated S. aureus to date. We analysed 97 S. aureus isolates from sheep and sheep products from the UK, Turkey, France, Norway, Australia, Canada and the USA using multilocus sequence typing (MLST) and spa typing. These were compared with 196 sheep isolates from Europe (n = 153), Africa (n = 28), South America (n = 14) and Australia (n = 1); 172 bovine, 68 caprine and 433 human S. aureus profiles. Overall there were 59 STs and 87 spa types in the 293 ovine isolates; in the 97 new ovine isolates there were 22 STs and 37 spa types, including three novel MLST alleles, four novel STs and eight novel spa types. Three main CCs (CC133, CC522 and CC700) were detected in sheep and these contained 61% of all isolates. Four spa types (t002, t1534, t2678 and t3576) contained 31% of all isolates and were associated with CC5, CC522, CC133 and CC522 respectively. spa types were consistent with MLST CCs, only one spa type (t1403) was present in multiple CCs. The three main ovine CCs have different but overlapping patterns of geographical dissemination that appear to match the location and timing of sheep domestication and selection for meat and wool production. CC133, CC522 and CC700 remained ovine-associated following the inclusion of additional host species. Ovine isolates clustered separately from human and bovine isolates and those from sheep cheeses, but closely with caprine isolates. As with cattle isolates, patterns of clonal diversification of sheep isolates differ from humans, indicative of their relatively recent host-jump.     

Clinical and molecular characteristics of nosocomial meticillin-resistant Staphylococcus aureus skin and soft tissue isolates from three Indian hospitals

We analysed risk factors for nosocomial meticillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTIs) in three Indian hospitals. We also determined antimicrobial resistance patterns and genotypic characteristics of MRSA isolates using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and staphylococcal cassette chromosome (SCCmec) typing. Medical records of 709 patients admitted to three tertiary hospitals with nosocomial S. aureus SSTIs were clinically evaluated. Antimicrobial susceptibility testing of patient isolates was performed in accordance with Clinical and Laboratory Standards Institute guidelines, with meticillin and mupirocin resistance confirmed by multiplex polymerase chain reaction. PFGE analysis of 220 MRSA isolates was performed, followed by MLST and SCCmec typing of a selected number of isolates. MRSA was associated with 41%, 31% and 7.5% of infections at the three hospitals, respectively. Multiple logistic regression analysis identified longer duration of hospitalisation [odds ratio (OR): 1.78; OR: 2.83 for ≥20 days], intra-hospital transfer (OR: 1.91), non-infectious skin conditions (3.64), osteomyelitis (2.9), neurological disorders (2.22), aminoglycoside therapy (1.74) and clindamycin therapy (4.73) as independent predictors for MRSA SSTIs. MRSA isolates from all three hospitals were multidrug resistant, with fifteen clones (I–XV) recognised. A majority of the strains possessed type III cassette. The common sequence type (ST) 239 was considered the signature MLST sequence for PFGE clone III. This major MRSA clone III was closely related to the UK EMRSA-1 and was significantly more resistant to antibiotics. Dissemination of multidrug-resistant MRSA clones warrants continuous tracking of resistant genotypes in the Indian subcontinent.     

全国细菌耐药监测网2014—2019年脑脊液标本细菌耐药监测报告

目的了解全国脑脊液标本分离细菌的分布及耐药性变迁。方法按照全国细菌耐药监测网(CARSS)方案,应用WHONET 5.6软件对2014—2019年所有CARSS成员单位上报的脑脊液标本分离细菌及药敏结果数据进行分析。结果2014—2019年脑脊液共分离细菌99741株,前五位依次为凝固酶阴性葡萄球菌(49902株,50.0%)、鲍曼不动杆菌(7692,7.7%)、大肠埃希菌(5561株,5.6%)、肺炎克雷伯菌(4653株,4.7%)、金黄色葡萄球菌(4295株,4.3%)。耐甲氧西林金黄色葡萄球菌(MRSA)的检出率由2014年的48.2%下降至2019年的39.9%;耐青霉素肺炎链球菌(PRSP)检出率一直在70%以上;屎肠球菌对多数测试药物的耐药率高于粪肠球菌;大肠埃希菌对头孢曲松的耐药率多数>60%,对碳青霉烯类抗生素的耐药率较低,但有上升趋势:对美罗培南的耐药率从2.6%上升至4.6%,对亚胺培南的耐药率从1.7%上升至4.5%;肺炎克雷伯菌对头孢曲松的耐药率>50%,对碳青霉烯类的耐药率快速增长:对美罗培南耐药率从13.1%上升至30.9%,对亚胺培南耐药率从12.6%上升至30.4%。鲍曼不动杆菌和铜绿假单胞菌对美罗培南耐药率均呈下降趋势,分别从74.2%下降至71.7%,32.6%下降至27.8%。结论脑脊液临床常见分离细菌的耐药性仍较强,耐药监测对中枢神经系统感染的有效治疗十分重要。