达托霉素等抗菌药物对499株血流感染革兰阳性球菌的体外抗菌活性

目的 评价达托霉素、万古霉素、替考拉宁、替加环素、头孢吡普、利奈唑胺等抗菌药物对血培养分离革兰阳性球菌的体外抗菌活性.方法 用微最肉汤稀释法测定达托霉素对499株血培养分离革兰阳性球菌的最小抑菌浓度(MIC)值,用琼脂稀释法测定其余9种抗菌药物MIC值,WHONET 5.4软件分析药敏数据.结果 葡萄球菌对达托霉素、万古霉索、替考拉宁、替加环素、头孢吡普和利奈唑胺的敏感率均为100%.达托霉素在1 mg/L浓度下可抑制所有的葡萄球菌.对于甲氧西林耐药的金黄色葡萄球菌(MRSA)和甲氧西林耐药的凝固酶阴性葡萄球菌(MRSCoN),其MIC50和MIC90均为0.5 mg/L.达托霉素对肠球菌的最高MIC为4 mg/L,粪肠球菌的MIC50和MIC90均为2 mg/L;屎肠球菌的MIC50和MIC90分别为2 mg/L和4 mg/L.1株对利奈唑胺耐药(MIC为8 mg/L)的粪肠球菌对达托霉索敏感(MIC为1 mg/L).3株携带vanA基因的屎肠球菌(万古霉素的MIC均大于32 mg/L,替考拉宁的MIC均为32 mg/L)对达托霉素、替加环素、利奈唑胺均敏感.达托霉素对肺炎链球菌和草绿色链球菌的MIC范围分别为0.032～0.250 mg/L和0.125～1.000 mg/L.结论 达托霉素作为新型的抗菌药物,对血流感染常见的革兰阳性球菌均有很好的体外抗菌活性.可成为临床治疗革兰阳性球菌特别是耐药菌感染的很好选择.     

2009年中国12家教学医院革兰阳性球菌耐药性研究

目的 调查2009年我国革兰阳性球菌临床分离株的耐药性.方法 收集2009年6-12月9个城市12家教学医院临床分离的1169株非重复革兰阳性球菌.采用琼脂稀释法测定抗菌药物的最低抑菌浓度(MIC)值.结果 金黄色葡萄球菌和凝固酶阴性葡萄球菌中耐苯唑西林菌株分别占45.3%(211/466)和89.5%(214/239);不同标本苯唑西林耐药金黄色葡萄球菌(MRSA)分离率为33.3%～68.1%.未发现对替考拉宁、万古霉素和利奈唑胺耐药的葡萄球菌.5.5%(7/128)的屎肠球菌对万古霉素耐药,未发现万古霉素耐药的粪肠球菌;粪肠球菌和屎肠球菌对利奈唑胺的敏感率约为99.1%(108/109).肺炎链球菌中青霉素中介株(P1SP)分离率为21.6%(48/222),仅发现1株青霉素耐药株(PRSP),占0.5%(1/222);未发现对替考拉宁、万古霉素和利奈唑胺耐药的肺炎链球菌.结论 葡萄球菌中苯唑西林耐药菌株仍有较高的分离率,不同标本类型MRSA的分离率有所不同.替考拉宁、万古霉素和利奈唑胺对葡萄球菌、粪肠球菌、屎肠球菌和肺炎链球菌具有很好的抗菌活性.     

葡萄球菌对利奈唑胺的耐药机制及其流行病学

葡萄球菌包括金黄色葡萄球菌(SA)和凝固酶阴性的葡萄球菌属(CoNS),是临床上最常见、最重要的革兰阳性球菌之一.万古霉素及替考拉宁是针对耐甲氧西林的SA(M RSA)、耐甲氧西林的CoNS(MRCoNS)感染的一线抗菌药物,但随着MRSA MIC值的漂移、异质性万古霉素中介的SA(hVISA,指万古霉素MIC值为1～2 mg/L,但其中不到10-6的菌株为能在万古霉素浓度＞2 mg/L的培养基中生长的MRSA菌株,与万古霉素治疗反应差、MRSA感染患者预后不佳密切相关)、万古霉素中介的SA乃至万古霉素耐药的SA的出现,美国感染病学会推荐利奈唑胺、达托霉素及替加环素等用于这类感染的抗菌治疗[1-2].     

2004-2005年度全国革兰阳性菌耐药监测(Mohnarin)

目的 监测2004-2005年度全国临床分离革兰阳性菌耐药状况.方法 选定全国17家医院作为成员单位,收集特定病房2004年10月1日至2005年9月30日分离的革兰阳性致病菌,用标准平皿二倍稀释法测定35种药物体外抗菌活性,计算最低抑菌浓度(MIC)50、MIC90,依据2004年美国国家临床实验标准委员会制订的标准计算细菌对抗菌药物的耐药率、中介率和敏感率.结果 共收集革兰阳性菌925株,包括葡萄球菌536株、肠球菌249株、链球菌137株和其他革兰阳性菌3株.苯唑西林耐药金黄色葡萄球菌与苯唑西林耐药表皮葡萄球菌的检出率分别为62.9%和82.9%;肺炎链球菌对青霉素的耐药率为10.5%,中介率为30.2%,不敏感率合计为40.7%;未发现对替考拉宁中介或耐药的肠球菌,5株肠球菌对万古霉素中介,分别为1株粪肠球菌、2株屎肠球菌、1株鹑鸡肠球菌和1株鸟肠球菌;术发现糖肽类不敏感葡萄球菌.结论 革兰阳性菌耐药呈明显上升趋势,青霉素不敏感肺炎链球菌、甲氧西林耐药的葡萄球菌比例高;细菌对大环内酯类耐药率高;未发现对万占霉素耐药的革兰阳性细菌.     

8704例孕妇产前阴道分泌物细菌培养及药敏试验结果分析

目的 分析孕妇产前阴道分泌物细菌培养及药敏结果,了解病原菌的分布及其药敏情况.方法 对8 704例孕妇产前进行阴道分泌物细菌培养及药敏试验.结果 8 704例孕妇阴道分泌物共培养出2 115株病菌,阳性率为24.30％,其中革兰阴性杆菌121株,革兰阳性球菌856株,真菌1 121株;革兰阴性杆菌中优势菌主要是大肠埃希菌（94株）和肺炎克雷伯菌（16株）;革兰阳性球菌中优势菌是B群无乳链球菌（548株）、金黄色葡萄球菌（167株）、粪肠球菌（34株）.大肠埃希菌对亚胺培南（100％）、美罗培南（100％）、厄他培南（98.94％）、阿米卡星（96.81％）、哌拉西林/他唑巴坦（96.81％）的敏感性较高;肺炎克雷伯菌对环丙沙星（100％）、亚胺培南（100％）、左氧氟沙星（100％）、美罗培南（100％）、替卡西林/克拉维酸（93.75％）、阿米卡星（93.75％）、头孢西丁（93.75％）、厄他培南（93.75％）的敏感性较高.B群无乳链球菌、金黄色葡萄球菌、粪肠球菌对万古霉素和达托霉素敏感率均为100％.结论 孕妇阴道细菌以革兰阳性球菌居多,真菌的生长比例较高.革兰阴性杆菌敏感率高的药物为亚胺培南、美罗培南、厄他培南和阿米卡星,革兰阳性球菌为万古霉素和达托霉素.     

我院细菌耐药性监测与抗菌药物敏感性分析

［摘要］　目的　了解该院细菌对抗菌药物的敏感性,指导临床抗菌药物合理应用。方法　监测该院2012年临床分离菌株的耐药性,以美国临床和实验室标准协会（CLSI）推荐的纸片扩散法测定其抗菌药物敏感性,用WHONET5.3软件分析结果。结果　按照监测方案,共获得780株细菌对抗菌药物敏感性结果,其中革兰阳性菌239株,占30.6%;革兰阴性菌541株,占69.4%。除绿脓杆菌外,所有革兰阴性杆菌对碳青霉烯类药物敏感率均在85.7%以上,哌拉西林他唑巴坦79.6%以上;所有葡萄球菌对万古霉素100.0%敏感,耐甲氧西林金黄色葡萄球菌（MRSA）检出率为51.1%,MRSA对氯霉素的敏感率为80.0%,对其他药物均较耐药;屎肠球菌和粪肠球菌对万古霉素和利奈唑胺最敏感(96.6%,100.0%;100.0%,100.0%)。结论　肺炎克雷伯菌、大肠埃希菌、鲍曼不动杆菌、肠杆菌属对碳青霉烯类敏感率较高,但铜绿假单胞菌对其耐药率较高。葡萄球菌属对万古霉素、利奈唑胺、替考拉宁敏感率均较高。     

感染性心内膜炎患者血培养阳性病原菌分布及耐药性分析

目的了解目前感染性心内膜炎(IE)的病原微生物情况及耐药性。方法回顾性研究2007²012年临床诊断的血培养阳性的IE病例,分析病原微生物特点及药物敏感性情况。结果分离的55株病原菌中,革兰阳性球菌47株(85.5%)、革兰阴性杆菌4株(7.3%)、革兰阳性杆菌3株(5.5%)、真菌1株(1.8%)。革兰阳性球菌中草绿色链球菌20株(36.4%)、其他链球菌15株(27.3%)、金黄色葡萄球菌4株(7.3%)、其他球菌8株(14.5%),革兰阴性杆菌中不动杆菌属2株(3.6%)、肺炎克雷伯杆菌1株(1.8%)、沙门菌属1株(1.8%)。草绿色链球菌对利奈唑胺、万古霉素完全敏感,对红霉素耐药率达到85.0%。金黄色葡萄球菌对左氧氟沙星、头孢唑啉、替考拉宁、头孢呋辛、利福平、头孢西丁敏感性达100%,对红霉素则完全耐药,对青霉素、克林霉素耐药达75%。结论草绿色链球菌和金黄色葡萄球菌是IE的最常见致病菌,临床医生应根据病原菌的种类及药敏实验选择并合理使用抗菌药物。     

糖尿病合并尿路感染的病原菌分布及药敏分析

目的探讨糖尿病合并尿路感染的病原菌分布及其对抗菌药物的耐药情况,为临床合理应用抗生素提供指导。方法对2011年6月—2014年6月间在该院住院的69例糖尿病合并尿路感染患者的临床资料进行回顾性分析。结果在69例糖尿病合并尿路感染患者中段尿标本中共检出92株病原菌,其中革兰阴性杆菌60株,占65.21%;革兰阳性菌25株,占27.17%;真菌7株,占7.61%。革兰阴性杆菌对亚胺培南高度敏感,革兰阳性菌中肠球菌对哌拉西林/他唑巴坦、万古霉素的耐药率较低,对其他抗菌药物的耐药率达40%~77%,金黄色葡萄球菌对万古霉素高度敏感,对青霉素耐药率达90%,对红霉素耐药率达85.5%。结论糖尿病合并尿路感染病原菌以革兰阴性杆菌为主,其次为革兰阳性球菌和真菌,对常用抗菌药物的耐药率较高,普遍存在多重耐药现象,开展病原菌及耐药性监测对于提高糖尿病合并尿路感染的诊治水平具有积极意义。     

2012年中国成人社区获得性呼吸道感染主要致病菌耐药性的多中心研究

目的 调查2012年我国11家医院成人社区获得性呼吸道感染病原菌的耐药性.方法 收集2012年1-12月全国11家中心分离的599株成人社区获得性呼吸道感染病原菌,其中肺炎链球菌381株,流感嗜血杆菌137株,卡他莫拉菌81株.采用琼脂稀释法测定抗菌药物的MIC值.结果 50％(300/599)的菌株分离自60岁以上的患者,16.2％(97/599)的菌株分离自40岁以下的患者.按照肺炎链球菌口服青霉素的折点判定标准,56.7％(216/381)的肺炎链球菌为青霉素不敏感菌株(PNSSP),肺炎链球菌对大环内酯类的耐药率超过90％(345/381),对口服头孢菌素的耐药率为39.9％ ～50.7％(152 ～ 193株).肺炎链球菌对左氧氟沙星和莫西沙星的敏感度分别为97.8％(372/381)和99％(377/381).PNSSP对头孢曲松、阿莫西林/克拉维酸、头孢克洛、头孢呋辛的耐药率显著高于青霉素敏感菌株(PSSP).流感嗜血杆菌对除氨苄西林(71.5％,272/381)和头孢克洛(75.2％,286/381)外的抗菌药物的敏感度均超过90％.流感嗜血杆菌中β-内酰胺酶阳性率为21.9％(30/137),且β-内酰胺酶阳性菌株对氨苄西林、头孢克洛、氯霉素和四环素的耐药性显著高于β-内酰胺酶阴性菌株.氟喹诺酮类药物对流感嗜血杆菌的作用效果明显.除克林霉素、阿奇霉素和克拉霉素对卡他莫拉菌作用较差外,其他药物对卡他莫拉菌均具有较高的抗菌活性.结论 大环内酯类和口服头孢菌素类药物对肺炎链球菌、流感嗜血杆菌和卡他莫拉菌的抗菌活性有限,左氧氟沙星和莫西沙星对肺炎链球菌、流感嗜血杆菌和卡他莫拉菌仍具有较高的抗菌活性.     

糖尿病足溃疡处病原菌分布情况及耐药性分析

目的观察糖尿病足溃疡分泌物病原菌分布情况及其耐药性分析,指导临床用药。方法回顾性分析2012年1月—2015年12月期间该院糖尿病患者足溃疡分泌物分离的292株病原菌的分布情况及其耐药性。结果糖尿病足病原菌以革兰阳性球菌为主(56.8%),其次是革兰阴性杆菌(39.7%)和真菌(3.5%);其中革兰阳性球菌以金黄色葡萄球菌比例最多,占42.2%,溶血性葡萄球菌占20.5%;而革兰阴性杆菌的分布为变形杆菌占25.9%,铜绿假单胞菌占24.1%。其药敏结果显示,在金黄色葡萄球菌中,对莫西沙星耐药率为0,MRSA占22.5%,未见对万古霉素、利奈唑胺、达托霉素耐药的革兰氏阳性菌;亚胺培南对革兰阴性杆菌抗菌敏感性较高,其他常用抗菌药均有不同程度的耐药。结论糖尿病足溃疡处病原菌分布以革兰阳性菌为主,万古霉素和莫西沙星有较高抗菌活性。通过对糖尿病足感染的病原菌及耐药性进行监测,及时调整抗菌药物,减少耐药菌产生。     

Susceptibility rates in Latin American nations: report from a regional resistance surveillance program (2011)

ObjectiveTo establish a resistance (R) surveillance program monitoring antimicrobial susceptibility patterns in Latin America (LATAM; Argentina [ARG], Brazil [BRA], Chile, Colombia [CBA], Costa Rica, Ecuador [ECU], Guatemala [GUA], Mexico [MEX], Panama [PAN], Peru, and Venezuela [VEN]).MethodsIn 2011, 4979 organisms were collected from 11 nations (20 laboratories) for susceptibility testing in a central laboratory design. Antimicrobials were tested by CLSI methods and results interpreted by CLSI and EUCAST breakpoints. Most common Gram-positive (Staphylococcus aureus [SA, 921], other staphylococci [CoNS; 299], enterococci [218], Streptococcus pneumoniae [SPN; 182], β-haemolytic streptococci [115]) and Gram-negative (E. coli [EC; 644], Klebsiella spp. [KSP; 517], Enterobacters [272], Pseudomonas aeruginosa [PSA; 586], Acinetobacters [ACB; 494]) pathogens were analyzed against linezolid (LZD), vancomycin (VAN), tigecycline (TIG), colistin (COL), cefoperazone/sulbactam (C/S), and amikacin (AMK).ResultsMRSA rates varied from 29% (CBA, BRA) to 79% (Peru); but LZD (MIC₉₀, 2 mg/L), TIG (MIC₉₀, 0.12 mg/L) and VAN (MIC₉₀, 1 mg/L) covered all strains. Enterococci showed a 14% VRE rate, highest in BRA and MEX; all inhibited by TIG and daptomycin, but not LZD (three non-susceptible with G2576T mutations or cfr). Penicillin-R among SPN and viridans streptococci was 51.6 and 41.1%, respectively. LZD overall R against Gram-positives was 0.3%. High ESBL rates were observed in EC (54–71%) and KSP (≥50%) from GUA, MEX and Peru, and six nations, respectively. Carbapenem-R in KSP was 9%, highest rates associated with KPC in BRA, CBA, ECU, PAN and VEN; also a NDM-1 in KSP from CBA. AMK, TIG, C/S and carbapenems were the broadest-spectrum agents tested against Enterobacteriaceae. Only COL inhibited >90% of PSA; COL and TIG (≤2 mg/L) covered ≥85% of ACB.ConclusionsLATAM nations demonstrated variable levels of antimicrobial R especially among Enterobacteriaceae (β-lactamase-mediated), PSA and ACB. MRSA (48%), VRE (14%) and multidrug-R SPN were also regional therapeutic challenges.     

Ceftaroline activity tested against contemporary Latin American bacterial pathogens (2011)

A total of 2484 target bacterial pathogens were collected (one per patient episode) from patients in 16 Latin American medical centers located in seven nations during 2011. Isolate identity was confirmed at a coordinating laboratory and susceptibility testing was performed for ceftaroline and comparator agents according to reference broth microdilution methods. A total of 30.0% of isolates were from respiratory tract, 29.4% from skin and skin structure, 21.4% from blood stream, 7.9% from urinary tract and 11.3% from other sites. Ceftaroline was active against Staphylococcus aureus (42.8% MRSA) with 83.6% of the isolates at ≤1 mg/L and all isolates at ≤2 mg/L (MIC₅₀₉₀, 0.25/2 mg/L). National MRSA rates ranged from a low of 28.8% in Colombia to a high of 68.1% in Chile. All Streptococcus pyogenes and Streptococcus agalactiae were susceptible to ceftaroline (MIC_50/90 values were at ≤0.015/≤0.015 mg/L for both). All Streptococcus pneumoniae were susceptible to ceftaroline, linezolid, tigecycline and vancomycin. Susceptibility to ceftriaxone was at 88.4% (CLSI non-meningitis interpretive criteria) and 73.9% (CLSI meningitis interpretive criteria) for all S. pneumoniae. Ceftriaxone susceptibility was only at 33.3% (CLSI non-meningitis interpretive criteria) and 0.0% (CLSI meningitis interpretive criteria) for penicillin-intermediate (penicillin MIC, 4 mg/L) strains. All Haemophilus influenzae (29.4% β-lactamase-positive) isolates were susceptible to ceftaroline, amoxicillin–clavulanate, ceftriaxone, and levofloxacin. For the Latin American region, the ESBL-phenotype rate was 37.6% for Escherichia coli and 53.3% for Klebsiella pneumoniae. Ceftaroline was not active against ESBL-phenotype strains but was active against >90.0% of the non-ESBL-phenotype. The spectrum of activity of ceftaroline against pathogens from Latin America indicates that it merits further study for its potential use in the Latin American region.     

Larvicidal activity of synthesized silver nanoparticles using Eclipta prostrata leaf extract against filariasis and malaria vectors

Mosquitoes transmit serious human diseases, causing millions of deaths every year. Use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides of synthesized natural products for vector control have been a priority in this area. In this study, larvicidal activity of synthesized silver nanoparticles (AgNPs) utilizing aqueous extract from Eclipta prostrata, a member of the Asteraceae was investigated against fourth instar larvae of filariasis vector, Culex quinquefasciatus say and malaria vector, Anopheles subpictus Grassi (Diptera: Culicidae). The synthesized AgNPs characterized by UV–vis spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). SEM analyses of the synthesized AgNPs were clearly distinguishable measured 35–60 nm in size. Larvae were exposed to varying concentrations of aqueous extract of synthesized AgNPs for 24 h. The maximum efficacy was observed in crude aqueous, and synthesized AgNPs against C. quinquefasciatus (LC₅₀ = 27.49 and 4.56 mg/L; LC₉₀ = 70.38 and 13.14 mg/L), and against A. subpictus (LC₅₀ = 27.85 and 5.14 mg/L; LC₉₀ = 71.45 and 25.68 mg/L) respectively. The chi-square value were significant at p < 0.05 level. These results suggest that the synthesized AgNPs have the potential to be used as an ideal eco-friendly approach for the control of the Culex tritaeniorhynchus and A. subpictus. This method is considered as a new approach to control vectors. Therefore, this study provides first report on the mosquito larvicidal activity of synthesized AgNPs against vectors.     

The impact of penicillin resistance on the outcome of invasive Streptococcus pneumoniae infection in children

Background: Invasive infections caused by Streptococcus pneumoniae with reduced susceptibility to penicillin are increasing in prevalence in Australia. Aims: To determine the impact of reduced susceptibility of S. pneumoniae to penicillin on morbidity, mortality and treatment of invasive infection. Methods: Retrospective case note review of children with invasive S. pneumoniae infection over a 26 month period. Penicillin minimum inhibitory concentrations (MIC) were determined by E test. Primary clinical outcome measures included days to defervescence, duration of hospital stay, complication rates and mortality. The secondary outcome of financial cost was examined. Comparisons between outcomes of patients with infections caused by susceptible and non‐susceptible strains were performed with Student's t test. Pearson χ², Mann‐Whitney U tests and multiple logistic regression. Results: Sixty‐eight episodes of invasive pneumococcal disease were reviewed: 14 isolates (21.1%) had reduced susceptibility or resistance to penicillin (PNSSP, MIC 0.125 mg/L‐1.5 mg/L). Ten patients had meningitis, 21 had pneumonia, 22 had bacteraemia with another focus and 15 had bacteraemia without an obvious focus. PNSSP were more common in patients with meningitis and pneumonia. No patients died. Overall, patients with infections caused by PNSSP had significandy longer hospitalisation and longer time to defervescence. Complication rates were not significantly different between groups. Outcome differences were no longer significant when meningitis patients were excluded from the analysis. The PNSSP group received more expensive intravenous antibiotics and their infections were significandy more costly to treat. Conclusions: Infections widi penicillin non‐susceptible S. pneumoniae are associated with higher morbidity than infections with penicillin susceptible strains, and treatment of diese infections is more expensive, due to higher drug costs and longer hospital stay.     

万古霉素等十种抗生素对耐苯唑西林葡萄球菌的体外活性比较

为了比较万古霉素等１０种抗生素对１９９５年分离的９５株耐苯唑西林的金黄色葡萄球菌和７２株凝固酶阴性葡萄球菌的体外活性，用ＮＣＣＬＳ颁布的琼脂稀释法测ＭＩＣ。结果受检的１０种抗生素中万古霉素的活性最好，其ＭＩＣ５０及ＭＩＣ９０分别为１ｍｇ／Ｌ及２ｍｇ／Ｌ，平均值为１２４ｍｇ／Ｌ；耐药率为０％。其次为壁霉素，其ＭＩＣ５０及ＭＩＣ９０分别为２ｍｇ／Ｌ及８ｍｇ／Ｌ，平均值为２５１ｍｇ／Ｌ；耐药率为２％。利福平ＭＩＣ５０及ＭＩＣ９０分别为０１２５ｍｇ／Ｌ及３２ｍｇ／Ｌ，平均值为０２２ｍｇ／Ｌ；耐药率为１４％。其它依ＭＩＣ９０的大小排序，为氧氟沙星，甲氧苄啶，红霉素，庆大霉素，磷霉素，磺胺甲恶唑等。用柱状图显示了前三种药的ＭＩＣ值的分离，万古霉素具有良好的分散性，全部落在敏感区，且为单峰。结果表明万古霉素对ＭＲＳＡ和ＭＲＳＣｏＮ有良好的抗菌活性。     

Neisseria gonorrhoeae: resistencias antimicrobianas y estudio de la dinámica poblacional. Situación en 2011 en Barcelona

Background

Due to the high rates of antimicrobial resistance to certain antibiotics, together with the emergence of Neisseria gonorrhoeae (NG) with reduced susceptibility and resistance to third-generation cephalosporins, gonococcal infection is becoming a public health problem. The objectives of the study were: To keep track of the antimicrobial susceptibility of NG strains obtained from January to August 2011. To study the population dynamics.

Methods

The antimicrobial susceptibility was studied by disk-diffusion and E-test. The genotyping was performed by NG-MAST method.

Results

Of a total of 100 strains studied, 59% showed intermediate sensitivity to penicillin and 9% were resistant. According to EUCAST, we detected 3 gonococci with reduced susceptibility to ceftriaxone, 10 to cefixime and one with high-level resistance to both antibiotics (MIC 1.5 μg/ml). MIC₅₀ and MIC₉₀ to cefixime were 0.016 and 0.125 μg/ml, respectively, whereas to ceftriaxone they were < 0.016 and 0.064 μg/ml, respectively. Almost all (99%) of the strains were resistant to doxycycline, 53% to ciprofloxacin, 3% to azithromycin, and 1% to spectinomycin. The most prevalent ST was ST1407, predominantly associated to resistance or reduced sensitivity to cephalosporins or macrolides.

Conclusions

NG has developed significant rates of resistance to various antibiotics. One strain has been detected with high level resistance to third generation cephalosporins, and several strains with reduced susceptibility. An increase in MIC₅₀ and MIC₉₀ to these antibiotics has also been observed. NG population structure remains stable and common to the rest of Europe, although two new ST (ST7226 and ST7227) have been identified that could be selected and acquire high levels of resistance to cephalosporins.     

Tratamiento con daptomicina en pacientes con bacteriemia

Community-acquired bacteremias assciated with healthcare and, especially, those of nosocomial origin, are mainly caused by Gram-positive microorganisms. Notable among this group are Staphylococcus spp, with an incidence of methicillin resistance of approximately 30% in S. aureus and of 70% in coagulase-negative staphylococcus, which is higher in patients admitted to intensive care units. Vancomycin has been the most widely used antibiotic in these situations but its toxicity, especially in the kidney, and reports of failure when used for the treatment of methicillin-resistant S. aureus (MRSA) and with a vancomycin MIC > 1 mg/L have led to the search for other treatments.Daptomycin is a new lipopeptide antibiotic that has been shown to be not inferior to vancomycin in a pivotal clinical trial in patients with bacteremia and right endocarditis due to S. aureus. Recent guidelines and consensus documents place daptomycin as an ideal alternative in these situations, indicating its use in MRSA bacteremia with a vancomycin MIC > 1 mg/L, as well as in patients whose renal dysfunction excludes the use of vancomycin therapy. Evidence of worse prognosis in MRSA bacteremia when empirical treatment is inappropriate has led to the recommendation of daptomycin as the first-choice drug in critically ill patients with suspected Gram-positive bacteremic infection and renal dysfunction and/or in hospitals where there is a high prevalence of MRSA with a MIC > 1 mg/L. The recommended dose in severely ill patients should be higher than 6 mg/kg/day.     

Infecciones causadas por bacterias grampositivas multirresistentes (Staphylococcus aureus y Enterococcus spp.)

Methicillin -resistant Staphylocccus aureus (MRSA) and multirresistant entorococci are still problematic in nosocomial infections and new challenges have emerged for their containment. MRSA has increased the multiresistant profile; it has been described vancomycin and linezolid resistant isolates and isolates with decreased daptomycin susceptibility. Moreover, new clones (ST398) have emerged, initially associated with piggeries, and new mec variants (mecC) with livestock origin that escape to the detection with current molecular methods based on mecA gene have been detected. In enterococci, linzeolid resistant isolates and isolates with deceased susceptibility to daptomycin have been described. Moreover, ampicillin resistant Enterococcus faecium due to β-lactamase production has been recently found in Europe. Control of MRSA isolates and multiresistant enteroccocci should combined antibiotic stewardship strategies and epidemiological measures, including detection of colonized patients in order to reduce colonization pressure and their transmission.     

Evaluation of MRSASelect? chromogenic medium for the early detection of methicillin-resistant Staphylococcus aureus from blood cultures

INTRODUCTION:

Staphylococcus aureus bacteremia is associated with considerable morbidity and mortality. In theory, reducing the turnaround time in reporting of methicillin-resistant S aureus (MRSA) among patients with bactermia could assist with the rapid optimization of antimicrobial therapy.

OBJECTIVE:

To evaluate the sensitivity and specificity of MRSASelect (Bio-Rad Laboratories, USA), a chromogenic medium, in the early detection of MRSA from blood cultures growing Gram-positive cocci in clusters, and to confirm that routine use of this medium would, in fact, reduce turnaround time for MRSA identification.

METHODS:

The present study was conducted at three microbiology laboratories in Manitoba. Between April 2010 and May 2011, positive blood cultures with Gram-positive cocci in clusters visualized on Gram stain were subcultured to both MRSASelect and routine media. MRSA isolates were identified using conventional microbiological methods from routine media and using growth with the typical colony morphology (pink colony) on MRSASelect medium.

RESULTS:

A total of 490 blood cultures demonstrating Gram-positive cocci in clusters on Gram stain were evaluated. S aureus was recovered from 274 blood cultures, with 51 S aureus isolates (51 of 274 [18.6%]) identified as MRSA. MRSASelect medium had a sensitivity of 98%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.8% for the recovery and identification of MRSA directly from positive blood culture bottles. In addition, use of MRSASelect medium was found to improve turnaround time in the detection of MRSA by almost 24 h relative to conventional methods.

DISCUSSION:

These data support the utility of MRSASelect medium for the rapid identification of MRSA from positive blood cultures. Further clinical studies are warranted to determine whether the improvement in turnaround time will result in a measurable reduction in suboptimal antimicrobial therapy and/or improvement in patient outcome.