铜绿假单胞菌对10种抗菌药物敏感性分析

目的调查我院临床分离的铜绿假单胞菌对10种抗菌药物的敏感性,分析其多重耐药特点,指导临床用药.方法收集我院2002-2004年临床分离368株铜绿假单胞菌,使用Kirby-Bauer纸片琼脂扩散法测定其对10种抗菌药物的抑菌环直径,按NCCLS 2002年规定判读结果.结果ICU分离菌对亚胺培南和美罗培南耐药率为54.3%和52.2%,分别高于非ICU28.8个百分点和34.7个百分点（P＜0.01）,对头孢吡肟、头孢他啶和氨曲南的耐药率高于非ICU 10.2～12.6个百分点（P＜0.05）;呼吸道标本分离株对哌拉西林、哌拉西林-三唑巴坦、头孢吡肟、亚胺培南、美罗培南、环丙沙星、庆大霉素和阿米卡星的耐药率高出非呼吸道标本12.2～25.4个百分点（P＜0.01）,对头孢他啶的耐药率比非呼吸道标本高10.1个百分点（P＜0.05）.结论我院ICU和呼吸道标本分离铜绿假单胞菌对多种抗菌药物的耐药率高于非ICU和非呼吸道标本分离株.     

重症监护病房革兰阴性杆菌耐药性监测

目的：调查从我院重症监护病房（ICU）患中分离的革兰阴性杆菌耐药状况，并探讨对耐药菌感染的治疗策略。方法：用E试验法测定100株革兰阴性杆菌对12种抗菌的最低抑菌浓度（MIC）。结果：亚胺培南和头孢哌酮-舒巴坦对所有受试菌仍保持最高抗菌活性，细菌的耐药率分别为9％和11％，哌拉西林-三唑巴坦、头孢吡肟次之，耐药率分别为19％和21％。阿米卡星、头孢他啶、阿莫西林-克拉维酸的耐药率分别为25％、26％和30％。其他抗菌药耐药率在43％-54％之间。头孢吡肟对铜绿假单胞菌抗菌活性最强，其敏感率达89％，头孢哌酮-舒巴坦、阿米卡星次之均为84％，亚胺培南、头孢他啶敏感率分别为79％和74％。筛选出超广谱β内酰胺酶（ESBLs）产生菌19株，抗菌活性最强的是亚胺培南、头孢哌酮-舒巴坦和哌拉西林-三唑巴坦，敏感率分别为84.1％、78.9％、和68.4％。结论：亚胺培南可作为ESBLs产生菌所致重症感染的首选药物，而β内酰胺酶抑制剂与β内酰胺酶类抗生素的复合制剂可作为治疗产β内酰胺酶耐药株感染的选用药物之一。     

儿童临床分离多重耐药铜绿假单胞菌的耐药性分析

目的了解儿童临床分离多重耐药铜绿假单胞菌的耐药特征。方法收集我院住院患儿中分离的120株多重耐药铜绿假单胞菌，作药敏试验，用琼脂稀释法测定抗菌药物的MIC值，按照2005年CLSI推荐标准判断结果。数据分析使用WHONET5．3软件。结果多重耐药铜绿假单胞菌对氨曲南的耐药率最高（86．7％），头孢他啶仍具较好的抗菌活性；环丙沙星耐药率最低（2．5％）。亚胺培南和美罗培南的耐药率分别达到34．2％、35．8％，两者MIC50和MIC50相同，分别为4和32mg／L。59株细菌对碳青霉烯类抗生素耐药，占49．2％。碳青霉烯类抗生素耐药株与非耐药株对头孢他啶、头孢吡肟、头孢哌酮-舒巴坦、哌拉西林-三唑巴坦的耐药率差异有显著性（P〈0．05）。结论目前从儿科临床分离多重耐药铜绿假单胞菌的多重耐药现象严重。     

重症监护病房常见非发酵糖细菌的耐药性分析

目的　探讨医院重症监护病房(ICU)感染患者常见非发酵糖细菌的耐药性。方法　用VITEK -ATB系统对该院1999至2 0 0 3年间ICU感染患者常见非发酵糖细菌监测资料进行统计分析。结果　铜绿假单胞菌对美洛培南、亚胺培南和阿米卡星的耐药率分别为8%、11%和12 % ,其次对头胞吡肟、妥布霉素、环丙沙星、头孢他啶和哌拉西林/三唑巴坦的耐药率分别为2 4 %、36 %、37%、39%和4 0 % ,其耐药率有上升趋势的抗生素是亚胺培南、环丙沙星;嗜麦芽窄食单胞菌对复方磺胺甲基异亚唑、培氟沙星、环丙沙星的耐药率分别为6 %、7%、11% ,其次对头孢他啶的耐药率为32 % ;在ICU ,鲍曼不动杆菌对亚胺培南暂无耐药性,其次对头孢吡肟、替卡西林/克拉维酸、哌拉西林/三唑巴坦和阿米卡星的耐药率分别为18%、2 9%、35 %和38%。结论　常见非发酵糖细菌的耐药性各有特点;铜绿假单胞菌对亚胺培南、环丙沙星的耐药性呈逐年上升的趋势。必须随时监测各病原菌的耐药性,做到合理用药,才有助于控制感染,延缓耐药。     

临床分离铜绿假单胞菌分布及耐药性分析

目的 了解铜绿假单胞菌的临床分布及耐药性特性。方法 对医院2007年7月至2008年10月细菌培养和药敏试验的结果进行回顾性分析。结果 共分离铜绿假单胞菌335株,占总病原菌9.2%;主要标本来源是痰液,占77.6%。高发病区是ICU病房。铜绿假单胞菌对丁胺卡那霉素、哌拉西林/他唑巴坦、妥布霉素、左氧氟沙星、头孢吡肟、庆大霉素、替卡西林及环丙沙星12种常用抗菌药物耐药率小于10%。对亚胺培南不敏感的铜绿假单胞菌对氨曲南、头孢他啶、环丙沙星、左氧氟沙星、哌拉西林/他唑巴坦的耐药率明显高于对亚胺培南敏感的铜绿假单胞菌(P<0.05)。结论 铜绿假单胞菌多重耐药现象普遍存在,建议治疗选用丁胺卡那霉素、哌拉西林/他唑巴坦、妥布霉素。     

下呼吸道感染常见病原菌及药敏分析

目的回顾分析院内下呼吸道感染病原菌的分布及耐药情况,为临床选用抗菌药物提供参考依据。方法收集住院下呼吸道感染患者痰标本分离的病原菌,采用纸片扩散法行药敏试验。结果分离出819株病原菌,其中革兰阴性杆菌574株,占70.1%,革兰阳性球菌154株,占18.8%,真菌91株,占11.1%。革兰阴性杆菌中前3位依次为：铜绿假单胞菌308株,占53.7%,鲍曼不动杆菌140株,占24.4%,大肠埃希菌56株,占9.8%;革兰阳性球菌中前3位为：金黄色葡萄球菌84株,占54.5%,溶血葡萄球菌42株,占27.3%,表皮葡萄球菌21株,占13.6%。耐药性分析：铜绿假单胞菌对头孢曲松耐药率最高,对阿米卡星、头孢吡肟、亚胺培南、美洛培南、哌拉西林/三唑巴坦耐药率较低。鲍曼不动杆菌对头孢曲松耐药率高,对阿米卡星、亚胺培南、美洛培南、哌拉西林/三唑巴坦耐药率低。大肠埃希菌对环丙沙星耐药率高,对阿米卡星、氨苄西林/舒巴坦、头孢他啶、亚胺培南、美洛培南、哌拉西林/三唑巴坦耐药率较低。结论革兰阴性杆菌是下呼吸道感染的常见病原菌,最常见为铜绿假单胞菌;药敏结果表明细菌耐药性较高,应加强病原菌检测及耐药性监测,合理使用抗菌药物。     

45株铜绿假单胞菌耐药性分析

目的：分析该院铜绿假单胞菌的临床分布和药敏情况,为临床用药提供参考。方法：按照《全国临床检验操作规程》培养鉴定临床标本中的铜绿假单胞菌,采用Kirby—Bauer纸片扩散法进行抗生素敏感性试验,应用LIS（Laboratory Information System）软件进行药敏情况分析。结果：45株铜绿假单胞菌临床主要分布情况：以呼吸道感染为主;抗生素耐药情况：氨苄青霉素、复方新诺明、头孢呋肟、头孢唑啉的耐药率均达达到100％,庆大霉素、头孢曲松、头孢他啶、氨曲南的耐药率分别为60％、46．7％、46．7％、35．6%,阿米卡星、哌拉西林／他唑巴坦、头孢吡肟、头孢派酮／舒巴坦的耐药率分别为22．2％、22．2％、20％、133％。左氧氟沙星、亚胺培南分别为4．4％和0％。结论：铜绿假单胞菌耐药情况比较严重,耐药率20％以下只有头孢派酮／舒巴坦、左氧氟沙星、亚胺培南。临床用药应根据药敏分析,合理使用抗生素。     

重症监护病房革兰阴性菌群变迁及耐药性研究

目的了解本地区重症监护病房的病原菌的菌种和耐药情况变迁,指导临床合理选用抗生素。方法2001年1月~2004年12月,从该院ICU患者标本中分离到453株细菌,其中革兰阴性菌280株。细菌鉴定及药敏试验采用VITEK-60全自动细菌鉴定仪。结果4年中病原菌感染率占首位的,分别是大肠埃希菌、产气肠杆菌、肺炎克雷伯菌和铜绿假单胞菌。对大肠埃希菌、产气肠杆菌和肺炎克雷伯菌活性最高的是亚胺培南(92%~100%)、头孢替坦(78%~94%);对铜绿假单胞菌活性最高的是阿米卡星(91%)和哌拉西林/三唑巴坦(79%);对嗜麦芽窄食单胞菌活性最高的是哌拉西林/三唑巴坦(100%)、头孢他啶(86%)、头孢吡肟(86%)和头孢替坦(86%)。不动杆菌的耐药率较高,对其活性最高的抗生素阿米卡星和亚胺培南的敏感率也仅为(58%~67%)。结论亚胺培南、头孢替坦、阿米卡星和哌拉西林/三唑巴坦等抗生素对革兰阴性杆菌保持较高的敏感性。建议临床根据药敏结果选用抗生素。     

耐亚胺培南铜绿假单胞菌耐药性及金属β-内酰胺酶的检测

目的 了解耐亚胺培南铜绿假单胞菌产金属β-内酰胺酶的状况及耐药性，为临床合理选用抗生素提供依据。方法 细菌鉴定、药敏实验采用WalkAway-40全自动微生物分析仪，金属β-内酰胺酶检测采用双纸片增效法。结果 铜绿假单胞菌对亚胺培南的耐药率从1999年的13．0％升高到2005年的39．1％。亚胺培南耐药的铜绿假单胞菌对阿米卡星、头孢他啶、哌拉西林／他巴坦和头孢吡肟的耐药率在60％～63％之间，对妥布霉素、氨曲南、庆大霉素、环丙沙星和哌拉西林的耐药率分别为66．5％、68．0％、70．7％、71．0％和72．2％，金属β-内酰胺酶的检出率为15，7％。结论 亚胺培南耐药的铜绿假单胞菌呈逐年增加的趋势，且多重耐药现象严重；产金屑β-内酰胺酶是铜绿假单胞菌对亚胺培南耐药的重要机制，实验室应加强对金属β-内酰胺酶的检测。     

256株非发酵菌临床分布和耐药性分析

目的了解医院感染常见非发酵菌的临床分布和耐药情况。方法常规方法进行细菌培养和鉴定,用kirby-Bauer法进行体外药物敏感试验。结果 256株非发酵菌中分离率居前3位的依次为铜绿假单胞菌占51.6%,不动杆菌属占18.0%,嗜麦芽寡养单胞菌占10.2%,铜绿假单胞菌耐药率为6.8%~70.0%,对亚胺培南、哌拉西林/他唑巴坦、头孢他啶、头孢吡肟、阿米卡星耐药率低;不动杆菌属的耐药率和铜绿假单胞相似;嗜麦芽寡养单胞菌耐药率为19.2%~84.6%,对哌拉西林/他唑巴坦、头孢他啶、头孢吡肟耐药率低,其他均存在较高耐药率。结论铜绿假单胞菌、不动杆菌属、嗜麦芽寡养单胞菌是引起医院感染主要的非发酵菌,对多种抗菌药物存在高耐药率,应加强临床病原学检测,根据药敏结果合理用药,减少医院感染发生。     

In-vitro activity of cefepime and other broad-spectrum antimicrobials against several groups of gram-negative bacilli and Staphylococcus aureus

The in vitro activity of cefepime was compared with that of amikacin, ceftazidime, imipenem, ciprofloxacin, and piperacillin-tazobactam by using the E-test against five groups of carefully selected organisms: Klebsiella pneumoniae (68 isololates), Pseudomonas aeruginosa (62), methicillin-susceptible Staphylococcus aureus (MSSA) (60), and two groups of Enterobacteriaceae (60 and 62 isolates, respectively). The bacteria were subdivided according to whether the infection was nosocomial or community-acquired, applying accepted and predefined criteria. These isolates were obtained from patients admitted to our medical center throughout 1998. We retrospectively compared antimicrobial susceptibilities of the study sample with those of the +/- 3000 bacterial strains isolated from blood stream infections since 1990: the study sample appeared to represent adequately the clinical databank. Presence of extended-spectrum beta-lactamase (ESBL) was determined in all groups of Enterobacteriaceae with the ESBL screening E-test strip. Of the 252 Gram-negative bacilli tested, 242 (96%) were susceptible to cefepime, whereas only 168 (67%) were susceptible to ceftazidime, 211 (84%) to amikacin, and 220 (87%) to piperacillin-tazobactam (p < 0.001). Imipenem was slightly superior to cefepime with only seven isolates resistant (3%), six of which were P. aeruginosa. Cefepime was more active against Enterobacteriaceae than ceftazidime (93% vs. 72%, p < 0.001). This superiority was most evident against nosocomial strains of K. pneumoniae, against which cefepime was > three times more active than ceftazidime. The high level of resistance seen in nosocomial isolates of K. pneumoniae is consistent with high rates of ESBL production (69%, compared with 15-26% in other Enterobacteriaceae). The MIC90 of cefepime to methicillin-sensitive S. aureus was 1.5 micrograms/mL, whereas that of ceftazidime was 4 micrograms/mL; the susceptibility rate of both was 100%. In conclusion, cefepime possesses in vitro potencies against MSSA and current clinical strains of Gram-negative bacilli, many of which harbor resistance to other antimicrobial agents. Hence, it seems very suitable for empiric coverage of serious nosocomial infections.     

耐亚胺培南铜绿假单胞菌的药敏情况与耐药机制

目的：探讨44株耐亚胺培南铜绿假单胞菌的药敏情况和产金属β-内酰胺酶的类型。方法：采用K-B法测定抗菌药物对细菌的体外抗菌活性，双纸片协同试验进行金属β-内酰胺酶筛选，PCR法进行金属β-内酰胺酶耐药基因IMP和IMP的检测。结果：阿米卡星敏感性最高为27．3％，其次为环丙沙星（20．5％）和头孢吡肟（15．9%）；44株耐亚胺培南铜绿假单胞菌中，扩增出IMP型阳性株4株，未检测到VIM型金属β-内酰胺酶基因。结论：对耐亚胺培南铜绿假单胞菌引起的感染，阿米卡星、环丙沙星和头孢吡肟可以考虑使用。北京天坛医院耐亚胺培南铜绿假单胞菌耐药机制中，产IMP型金属β-内酰胺酶起着重要作用。     

Surveillance for antimicrobial susceptibility among clinical isolates of Pseudomonas aeruginosa and Acinetobacter baumannii from hospitalized patients in the United States, 1998 to 2001

Pseudomonas aeruginosa and Acinetobacter baumannii are the most prevalent nonfermentative bacterial species isolated from clinical specimens of hospitalized patients. A surveillance study of 65 laboratories in the United States from 1998 to 2001 found >90% of isolates of P. aeruginosa from hospitalized patients to be susceptible to amikacin and piperacillin-tazobactam; 80 to 90% of isolates to be susceptible to cefepime, ceftazidime, imipenem, and meropenem; and 70 to 80% of isolates to be susceptible to ciprofloxacin, gentamicin, levofloxacin, and ticarcillin-clavulanate. From 1998 to 2001, decreases in antimicrobial susceptibility (percents) among non-intensive-care-unit (non-ICU) inpatients and ICU patients, respectively, were greatest for ciprofloxacin (6.1 and 6.5), levofloxacin (6.6 and 3.5), and ceftazidime (4.8 and 3.3). Combined 1998 to 2001 results for A. baumannii isolated from non-ICU inpatients and ICU patients, respectively, demonstrated that >90% of isolates tested were susceptible to imipenem (96.5 and 96.6%) and meropenem (91.6 and 91.7%); fewer isolates from both non-ICU inpatients and ICU patients were susceptible to amikacin and ticarcillin-clavulanate (70 to 80% susceptible); and <60% of isolates were susceptible to ceftazidime, ciprofloxacin, gentamicin, or levofloxacin. From 1998 to 2001, rates of multidrug resistance (resistance to at least three of the drugs ceftazidime, ciprofloxacin, gentamicin, and imipenem) showed small increases among P. aeruginosa strains isolated from non-ICU inpatients (5.5 to 7.0%) and ICU patients (7.4 to 9.1%). From 1998 to 2001, rates of multidrug resistance among A. baumannii strains isolated from non-ICU inpatients (27.6 to 32.5%) and ICU patients (11.6 to 24.2%) were higher and more variable than those observed for P. aeruginosa. Isolates concurrently susceptible, intermediate, or resistant to both imipenem and meropenem accounted for 89.8 and 91.2% of P. aeruginosa and A. baumannii isolates, respectively, studied from 1998 to 2001. In conclusion, for aminoglycosides and most beta-lactams susceptibility rates for P. aeruginosa and A. baumannii were constant or decreased only marginally (相似文献   

2006—2009年铜绿假单胞菌分布及耐药性分析

目的分析2006-2009年北京阜外心血管病医院临床分离681株铜绿假单胞菌对抗菌药物的耐药情况。方法采用全自动微生物分析仪VITEK 32进行细菌鉴定及药敏试验,并用WHONET 5.4对其耐药性进行分析。结果 4年共分离铜绿假单胞菌681株,以呼吸道标本分离株为主,占76.1%。分离菌对抗菌药耐药率较低的有头孢哌酮-舒巴坦(20.7%)、哌拉西林-他唑巴坦(12.6%)、头孢他啶(24.5%)、头孢吡肟(18.5%)、阿米卡星(5.0%)、庆大霉素(14.2%)和环丙沙星(14.1%)。对亚胺培南及美罗培南的耐药率分别为24.2%和20.6%。结论铜绿假单胞菌是医院感染的重要病原菌,了解其临床分布和进行药敏试验,为合理选用抗生素提供依据。     

耐亚胺培南铜绿假单胞菌产金属β-内酰胺酶的研究

目的检测该院2005年4~7月住院患者耐亚胺培南铜绿假单胞菌(PA)产金属β-内酰胺酶(MBL)的情况,为难治性感染治疗提供参考。方法VITEK-60鉴定细菌及测定PA对抗菌药物的耐药性;纸片法检测PA产MBL。结果共检出PA103株,耐亚胺培南PA47株,同时耐头孢他啶16株,其中产MBL的PA8株,占所分离PA的7.8%,占耐亚胺培南PA的17.0%。8株产酶菌株中除1株对左旋氧氟沙星敏感外,对羧苄青霉素、阿米卡星、替卡西林/克拉维酸、头孢哌酮、头孢他啶、头孢吡肟、奈替米星、复方增效磺胺、哌拉西林/他唑巴坦、环丙沙星等抗生素均耐药;非产酶菌株仅有2株对羧苄青霉素敏感,1株对阿米卡星敏感,对其他抗生素均耐药。结论临床感染分离的PA、产酶菌株与非产酶菌株均呈多重耐药性。产MBL是PA对头孢类及碳青酶烯类抗生素耐药的机制之一,实验室对其正确检测可帮助临床合理选用抗菌药物,并减少耐药性的扩散。     

耐亚胺培南铜绿假单胞菌的耐药性分析及金属β-内酰胺酶的检测

目的调查盐城市第一人民医院住院患者送检标本分离的铜绿假单胞菌对亚胺培南的耐药水平及其产金属β-内酰胺酶(MBLs)的情况。方法临床标本分离的铜绿假单胞菌采用法国生物梅里埃细菌鉴定及药敏检测系统进行细菌鉴定与药物敏感性试验;采用纸片协同实验来检测铜绿假单胞菌产金属β-内酰胺酶的情况。结果 236株铜绿假单胞菌中有63株对亚胺培南耐药,耐药率为26.69%,耐亚胺培南铜绿假单胞菌对阿米卡星、庆大霉素、头孢哌酮/舒巴坦、哌拉西林/他唑巴坦、环丙沙星、氨曲南部分耐药,耐药率分别为45.12%、50.33%、59.74%、61.43%、62.12%和63.16%;对头孢他啶、头孢吡肟、哌拉西林、美罗培南耐药率较高;63株耐亚胺培南铜绿假单胞菌金属β-内酰胺酶的检出率为38.10%(24/63)。结论金属β-内酰胺酶的产生是铜绿假单胞菌对碳青霉烯类抗生素耐药的重要机制之一,实验室应加强对产酶菌株的监测,为临床合理选用抗生素提供有效依据。     

Phenotypic antimicrobial resistance patterns in Pseudomonas aeruginosa and Acinetobacter: results of a Multicenter Intensive Care Unit Surveillance Study, 1995-2000

Susceptibility data from the Intensive Care Unit (ICU) Surveillance Study for 10,361 isolates of Pseudomonas aeruginosa and 2,573 isolates of Acinetobacter tested at centers in the United States during 1995 to 2000 were analyzed. In all years, amikacin was the most active antimicrobial agent against P. aeruginosa, and imipenem was the most active agent against Acinetobacter. Resistance of both organisms to common therapeutic agents tested throughout the analysis period increased from 1995 to 2000, although the increase was not consistent for all drugs from year to year. The increases were higher among Acinetobacter, and for both organisms, the increase in resistance was greatest for ciprofloxacin. Among all P. aeruginosa tested in 1999 and 2000, resistance to ciprofloxacin was 9-11% higher for isolates from patients on general hospital wards than those from ICUs. Of the 3424 ICU isolates of P. aeruginosa tested in 1999 and 2000, 77 (2.2%) were multidrug-resistant (i.e., resistant to piperacillin, ceftazidime, imipenem, and gentamicin). Twenty (3.9%) isolates of Acinetobacter in 1999 and seven (1.9%) in 2000 were resistant to imipenem, ceftazidime, piperacillin-tazobactam, ciprofloxacin, and amikacin. Although resistance in both P. aeruginosa and Acinetobacter increased, multidrug-resistant (to > or =4 agents) strains were uncommon.     

重症监护病房铜绿假单胞菌及鲍曼不动杆菌药敏分析

目的了解2006～2007年重症监护病房患者铜绿假单胞菌及鲍曼／溶血不动杆菌的药敏及耐药变化，为合理应用抗菌药物及指导临床用药提供参考。方法用美国DadeBehring公司Microscan WalkAway-40SI全自动微生物分析仪进行菌株鉴定及药敏试验，并对耐药结果进行分析。结果铜绿假单胞菌总体敏感率较高的是亚胺培南、头孢吡肟、哌拉西林／他唑巴坦等，2年间耐药性变化显著的为阿米卡星。对鲍曼／溶血不动杆菌较敏感的是亚胺培南、氨苄西林／舒巴坦等，耐药性显著变化的有阿米卡星、头孢吡肟、头孢曲松、头孢噻肟及头孢他啶。结论临床应重视药敏试验结果，严格控制抗菌药物的使用。     

Geographic variations in activity of broad-spectrum beta-lactams against Pseudomonas aeruginosa: summary of the worldwide SENTRY Antimicrobial Surveillance Program (1997-2000)

With reports of increasing resistance to antimicrobial agents among Pseudomonas aeruginosa clinical isolates worldwide, the activities of cefepime and eight other broad-spectrum beta-lactams against 6969 isolates collected during 1997-2000 from the four regions of the SENTRY Antimicrobial Surveillance Program. P. aeruginosa isolates were tested by the reference broth microdilution method against nine beta-lactam antimicrobial agents (aztreonam, cefepime, ceftazidime, imipenem, meropenem, piperacillin +/- tazobactam, ticarcillin +/- clavulanate), three aminoglycosides (amikacin, gentamicin, tobramycin), and two fluoroquinolones (ciprofloxacin, levofloxacin). The strains were contributed by more than 100 medical centers. National Committee for Clinical Laboratory Standards criteria were used to identify susceptible and resistant isolates. P. aeruginosa strains from Latin America were generally the most resistant to all classes of antimicrobials, compared with strains from other regions. The beta-lactams exhibited a wide range of potency, with carbapenems most active (meropenem, 80-91% susceptible; imipenem, 76-88% susceptible). Piperacillin/tazobactam was the most active penicillin (77-80% susceptible), and cefepime (67-83% susceptible) had an average 2% (range, 0.7-3.5%) greater susceptibility rate than ceftazidime (66-80% susceptible) across all regions. The rank order of beta-lactam activity according to percent resistant isolates in North American P. aeruginosa strains was: meropenem (4.8% resistant) > cefepime (6.8%) > imipenem (8.6%) > piperacillin/tazobactam (10.3%) > piperacillin (12.9%). Only 2.3% and 6.5% of isolates were resistant to amikacin or tobramycin, respectively, and nearly 16% of P. aeruginosa strains were resistant to ciprofloxacin. Compared with other geographic regions, strains of P. aeruginosa remain most susceptible in North America. In all regions, aminoglycosides in combination with carbapenems, cefepime, or piperacillin/tazobactam would provide more potential antipseudomonal activity than fluoroquinolone combinations for wide-spectrum empiric regimens.     

Activity of levofloxacin and ciprofloxacin in combination with cefepime, ceftazidime, imipenem, piperacillin-tazobactam and amikacin against different Pseudomonas aeruginosa phenotypes and Acinetobacter spp

BACKGROUND: Combination therapy is used to widen the antimicrobial spectrum, minimize toxicity and prevent the emergence of resistant mutants. METHODS: Synergy between levofloxacin or ciprofloxacin and ceftazidime, cefepime, imipenem, piperacillin-tazobactam and amikacin was evaluated by checkerboard assay with 55 strains and by time-kill curves with 8 strains of Pseudomonas aeruginosa and Acinetobacter spp. RESULTS: In the checkerboard assay, synergy and additivity were the most frequent effects observed among all the combinations against P. aeruginosa and Acinetobacter spp., with no significant differences between the two fluoroquinolones. No antagonism was observed. In the time-kill curves, synergy was evidenced against all the tested strains, at least for one combination at one of the time points considered. Levofloxacin and ciprofloxacin combined with ceftazidime, as well as levofloxacin plus amikacin, were synergistic for all the strains tested. CONCLUSION: Combinations of fluoroquinolones with beta-lactams or amikacin show an enhanced activity against P. aeruginosa and Acinetobacter spp.