Comparison of community-associated and health care-associated methicillin-resistant Staphylococcus aureus in Canada: results of the CANWARD 2007-2009 study

This study assessed the demographics, antimicrobial susceptibility, and molecular epidemiology of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and health care-associated MRSA (HA-MRSA) in Canadian hospitals between 2007 and 2009. Among 3589 S. aureus, 889 (24.8%) were MRSA; 224 (25.2%) were CA-MRSA genotypes and 644 (72.4%) were HA-MRSA genotypes. The prevalence of CA-MRSA genotypes increased from 19.5% in 2007 to 31.9% in 2009 (P < .001). CMRSA10/USA300 (73.7%) was the predominant CA-MRSA epidemic type; the most common HA-MRSA epidemic type was CMRSA2/USA100/800 (83.5%). CA-MRSA genotypes carried SCCmec type IVa (98.2%) and were largely agr type I (73.2%). Most HA-MRSA genotypes were SCCmec type II (81.2%) and agr type II (83.4%). Panton-Valentine leukocidin was detected in 201/224 (89.7%) CA-MRSA genotypes and 3/644 (0.5%) HA-MRSA genotypes. An increase in vancomycin minimum inhibitory concentration (MIC) was observed in HA-MRSA genotypes overall, with 1.3% (4/305) of strains in 2007 and 4.6% (7/152) in 2009 exhibiting vancomycin MICs of 2 μg/mL. No MRSA resistance occurred with linezolid, daptomycin, or tigecycline. In conclusion, CA-MRSA genotypes represented 25.2% of all MRSA and continue to increase in prevalence in Canadian hospitals.     

2007-2009年鲍曼不动杆菌的耐药性分析

目的探讨2007年1月至2009年6月浙江省乐清市人民医院检出的鲍曼不动杆菌(AB)对常用抗生素的耐药性变化趋势,以指导临床合理选用抗生素。方法对该院2007年1月至2009年6月分离的非重复的革兰阴性杆菌使用法国生物梅里埃公司ATB细菌鉴定仪鉴定菌种,并做药敏试验,以明确AB对常用抗菌药物的体外耐药情况。结果 220株AB中85株来自重症监护病房(ICU),85%分离自痰标本。哌拉西林的耐药率从19.5%上升至66.7%。头孢噻肟、头孢他啶和头孢吡肟的耐药率从10%左右上升到60%以上。头孢呋辛的耐药率2008年达到97.7%。亚胺培南的耐药率从5.2%上升至56.1%。氨基糖苷类和喹诺酮类的耐药率均增高。从ICU分离到的AB比非ICU的AB的耐药率普遍高30%以上。结论 AB对多种抗菌药物耐药性迅速上升。应改善医疗环境条件,增强医务人员无菌观念,合理使用抗菌药物,加强对该菌耐药性的监测,以延缓耐药菌株上升,预防和控制病区内AB流行。     

Antimicrobial susceptibility of 15,644 pathogens from Canadian hospitals: results of the CANWARD 2007-2009 study

The CANWARD study (Canadian Ward Surveillance Study) assessed the antimicrobial susceptibility of a variety of available agents against 15 644 pathogens isolated from patients in Canadian hospitals between 2007 and 2009. The most active (based on MIC data) agents against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci were daptomycin, linezolid, tigecycline, and vancomycin (MRSA only) with MIC(90)'s (μg/mL) of 0.25 and 2, 2 and 2, 0.5 and 0.12, and 1, respectively. The most active agents against extended-spectrum β-lactamase-producing Escherichia coli were colistin (polymyxin E), doripenem, ertapenem, meropenem, and tigecycline with MIC(90)'s (μg/mL) of 1, ≤ 0.12, 0.25, ≤ 0.12, and 1, respectively. The most active agents against Pseudomonas aeruginosa were amikacin, cefepime, ceftazidime, colistin, doripenem, meropenem, and piperacillin-tazobactam with MIC(90)'s (μg/mL) of 32, 16, 32, 2, 4, 8, and 64, respectively. Overall, the most active agents versus Gram-positive cocci from Canadian hospitals were vancomycin, linezolid, daptomycin, and tigecycline and versus Gram-negative bacilli were amikacin, cefepime, doripenem, ertapenem (excluding Pseudomonas aeruginosa), meropenem, piperacillin-tazobactam, and tigecycline (excluding Pseudomonas aeruginosa).     

Antimicrobial resistance in urinary tract pathogens in Canada from 2007 to 2009: CANWARD surveillance study

From January 2007 to December 2009, an annual Canadian national surveillance study (CANWARD) tested 2,943 urinary culture pathogens for antimicrobial susceptibilities according to Clinical and Laboratory Standards Institute guidelines. The most frequently isolated urinary pathogens were as follows (number of isolates, percentage of all isolates): Escherichia coli (1,581, 54%), enterococci (410, 14%), Klebsiella pneumoniae (274, 9%), Proteus mirabilis (122, 4%), Pseudomonas aeruginosa (100, 3%), and Staphylococcus aureus (80, 3%). The rates of susceptibility to trimethoprim-sulfamethoxazole (SXT) were 78, 86, 84, and 93%, respectively, for E. coli, K. pneumoniae, P. mirabilis, and S. aureus. The rates of susceptibility to nitrofurantoin were 96, 97, 33, and 100%, respectively, for E. coli, enterococci, K. pneumoniae, and S. aureus. The rates of susceptibility to ciprofloxacin were 81, 40, 86, 81, 66, and 41%, respectively, for E. coli, enterococci, K. pneumoniae, P. mirabilis, P. aeruginosa, and S. aureus. Statistical analysis of resistance rates (resistant plus intermediate isolates) by year for E. coli over the 3-year study period demonstrated that increased resistance rates occurred only for amoxicillin-clavulanate (from 1.8 to 6.6%; P < 0.001) and for SXT (from 18.6 to 24.3%; P = 0.02). For isolates of E. coli, in a multivariate logistic regression model, hospital location was independently associated with resistance to ciprofloxacin (P = 0.026) with higher rates of resistance observed in inpatient areas (medical, surgical, and intensive care unit wards). Increased age was also associated with resistance to ciprofloxacin (P < 0.001) and with resistance to two or more commonly prescribed oral agents (amoxicillin-clavulanate, ciprofloxacin, nitrofurantoin, and SXT) (P = 0.005). We conclude that frequently prescribed empirical agents for urinary tract infections, such as SXT and ciprofloxacin, demonstrate lowered in vitro susceptibilities when tested against recent clinical isolates.     

2007～2010年泰安医院临床主要病原菌分布及两种主要非发酵菌的耐药分析

目的调查临床主要病原菌的分布及两种主要非发酵菌耐药性的变化。方法回顾分析2007～2010年临床分离的病原菌和两种主要非发酵菌的耐药性。结果医院常见病原菌主要为铜绿假单胞菌(16.0%～20.7%)、大肠埃希杆菌(11.7%～18.4%)、鲍曼不动杆菌(10.4%～14.2%)、肺炎克雷伯杆菌(12.2%～16.7%)、白假丝酵母菌(6.0%～9.6%)和葡萄球菌(3.7%～11.7%);铜绿假单胞菌和鲍曼不动杆菌对碳青霉烯类抗生素亚胺培南耐药性呈现增强趋势,分别为47.3%～70.9%,12.6%～45.0%。耐头孢哌酮/舒巴坦的鲍曼不动杆菌年年上升,由2007年的11.9%上升到2010年的25.0%。结论铜绿假单胞菌和鲍曼不动杆菌是医院感染的常见菌,对碳青霉烯类抗生素及头孢哌酮/舒巴坦耐药较严重,医师应依据检验结果个性化用药,医院需采取有效措施,降低碳青霉烯类抗生素及头孢哌酮/舒巴坦耐药性。     

Prevalence of antimicrobial resistant pathogens from blood cultures from Canadian hospitals: results of the CANWARD 2007-2009 study

This study assessed the epidemiology and antimicrobial resistance of pathogens associated with bloodstream infections in Canadian hospitals between 2007 and 2009. Tertiary-care medical centers representing 8 of 10 Canadian provinces submitted bloodstream infection pathogens from patients attending hospital clinics, emergency rooms, medical/surgical wards, and intensive care units. Over 8,000 blood culture pathogens were collected. The 10 most common pathogens (representing 80.9% of all isolates) were Escherichia coli (1856 [22.6%]), Staphylococcus aureus (1457 [17.7%] including 1101 methicillin-susceptible Staphylococcus aureus and 356 methicillin-resistant Staphylococcus aureus), coagulase-negative staphylococci (907 [11.0%]), Klebsiella pneumoniae (600 [7.3%]), Streptococcus pneumoniae (470 [5.7%]), Enterococcus faecalis (360 [4.4%]), Pseudomonas aeruginosa (333 [4.0%]), viridans group streptococci (321 [3.9%]), Enterobacter cloacae (193 [2.3%]), and Streptococcus pyogenes (159 [1.9%]). The most active agents against Gram-negative bacilli were carbapenems (e.g., meropenem and ertapenem) and piperacillin-tazobactam, while for Gram-positive cocci, they were vancomycin, linezolid, and daptomycin.     

铜绿假单胞菌和鲍曼不动杆菌感染分布特征及耐药性分析

目的 探讨铜绿假单胞菌和鲍曼不动杆菌的分布特征及对多种抗菌药物的耐药性变迁。方法 收集2012年1月至2014年12月该院分离的铜绿假单胞菌和鲍曼不动杆菌,采用琼脂扩散法做药物敏感试验,比较其对抗菌药物的耐药性变迁。结果共分离出病原菌3 710例,铜绿假单胞菌分离214株(5.8%),鲍曼不动杆菌分离347株(9.4%)。铜绿假单胞菌3年感染率分别为7.3%、6.6%、4.7%,呈逐年减少趋势,鲍曼不动杆菌感染率分别为7.6%、8.8%、10.3%,呈逐年增加趋势。标本来源主要以痰液、创面分泌物、尿液为主。铜绿假单胞菌和鲍曼不动杆菌感染菌株以重症监护室(ICU)检出率最高,分别为27.6%和34.9%。铜绿假单胞菌对头孢他啶、阿米卡星、亚胺培南的耐药率均有逐年增高趋势;鲍曼不动杆菌对哌拉西林/他唑巴坦、亚胺培南耐药率逐年增高;多粘菌素B耐药率逐年下降。结论 铜绿假单胞菌和鲍曼不动杆菌对抗菌药物耐药率逐年增高,尤其对碳青霉烯类耐药情况日趋严重,因此需加强对铜绿假单胞菌及鲍曼不动杆菌的耐药性监测,指导临床合理应用抗菌药物。     

DNA microarray-based detection of nosocomial pathogenic Pseudomonas aeruginosa and Acinetobacter baumannii

Infection by nosocomial pathogenic bacteria is increasingly becoming a major threat to the patients in the hospital. We have developed a diagnostic DNA microarray for the detection of two important nosocomial pathogens, Pseudomonas aeruginosa and Acinetobacter baumannii. The diagnostic DNA microarray contains the species-specific probes of 15mer oligonucleotides designed based on the sequences of 23S ribosomal DNA. The performance of DNA microarray in diagnosing P. aeruginosa and A. baumannii was evaluated using reference bacteria as well as clinical specimens such as blood, stool, pus, sputum, urine and cerebrospinal fluid. Using this DNA microarray, A. baumannii could be successfully detected in 11 out of 13 clinical specimens, thus giving the sensitivity of 84.6% with the specificity of 100% and the positive predictive value of 100%. P. aeruginosa could also be detected in 25 out of 26 clinical specimens, showing the sensitivity of 96.2%, the specificity of 100%, and the positive predictive value of 100%. These results suggest that two nosocomial pathogens, P. aeruginosa and A. baumannii, can be efficiently diagnosed by using the DNA microarray developed in this study.     

Multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii: resistance mechanisms and implications for therapy

Pseudomonas aeruginosa and Acinetobacter baumannii are major nosocomial pathogens worldwide. Both are intrinsically resistant to many drugs and are able to become resistant to virtually any antimicrobial agent. An increasing prevalence of infections caused by multidrug-resistant (MDR) isolates has been reported in many countries. The resistance mechanisms of P. aeruginosa and A. baumannii include the production of β-lactamases, efflux pumps, and target-site or outer membrane modifications. Resistance to multiple drugs is usually the result of the combination of different mechanisms in a single isolate or the action of a single potent resistance mechanism. There are many challenges in the treatment of MDR P. aeruginosa and A. baumannii, especially considering the absence of new antimicrobials in the drug-development pipeline. In this review, we present the major resistance mechanisms of P. aeruginosa and A. baumannii, and discuss how they can affect antimicrobial therapy, considering recent clinical, microbiological, pharmacokinetic and pharmacodynamic findings of the main drugs used to treat MDR isolates.     

铜绿假单胞菌和鲍曼不动杆菌临床感染和耐药性分析

目的探讨铜绿假单胞菌和鲍曼不动杆菌的筘床感染分布及其药敏情况,为临床合理使用抗菌药物和预防多重耐药菌株的产生提供依据。方法回顾性分析了642株铜绿假单胞茼和570株鲍曼不动杆菌感染科室分布及耐药情况。结果铜绿假单胞菌和鲍曼不动杆菌感染的科室主要集中在重症监护病房（ICU）、呼吸科、神经外科、神经内科;氨苄西林和头孢唑啉对铜绿假单胞菌和鲍曼不动杆茸的抗菌作用最差,耐药率大于95％;铜绿假单胞茴对亚胺培南、美洛培南、头孢哌酮／舒巴坦、多粘菌素敏感性最高;鲍曼不动杆菌对亚胺培南和美罗培南的敏感性有所降低,其耐药率在15％左右,对多粘菌素的敏感性最高。结论铜绿假单胞菌争鲍曼不动杆茼临床分离株多来自ICU病房;氨苄西林和头孢唑啉已经不适于铜绿假单胞菌和鲍曼不动杆菌感染的治疗,亚胺培南、芙洛培南、多粘茼素可作为临床经验性用药;临床应重视合理使用抗生素,加强对铜绿假单胞菌和鲍曼不动杆菌的耐药性监蒯,减少多重耐药菌的产生。     

鲍曼不动杆菌和铜绿假单胞菌在医院感染中的地位及耐药分析

目的了解鲍曼不动杆菌和铜绿假单胞菌在医院感染中的地位,分析其对临床常用抗菌药物的耐药情况。方法鲍曼不动杆菌和铜绿假单胞菌的鉴定和药敏采用法国生物梅里埃公司的VITEK-2系统进行药物的最低抑菌浓度(M IC)检测。结果铜绿假单胞菌和鲍曼不动杆菌在医院感染中是重要的致病菌。在呼吸道感染标本中铜绿假单胞菌和鲍曼不动杆菌分别位居前一、二。对铜绿假单胞菌仍保持较高的抗菌活性的抗菌药物(耐药率均<20%)有阿米卡星、头孢他啶、环丙沙星、亚胺培南、妥布霉素、头孢吡肟、左旋氧氟沙星、哌拉西林/他唑巴坦、美洛培南。对鲍曼不动杆菌仍保持较高的抗菌活性的抗菌药物(耐药率均<20%)只有阿米卡星和亚胺培南。耐亚胺培南鲍曼不动杆菌的耐药性很高,除阿米卡星耐药率是28.4%外,其余的抗菌药物的耐药率均高于60%。结论虽然耐亚胺培南鲍曼不动杆菌的多重耐药性比耐亚胺培南铜绿假单胞菌更为显著,但鲍曼不动杆菌和铜绿假单胞菌在我院的医院感染菌中的地位同样重要,在医院感染的防控中值得关注。     

In vitro activity of ceftobiprole against frequently encountered aerobic and facultative Gram-positive and Gram-negative bacterial pathogens: results of the CANWARD 2007-2009 study

The in vitro activity of ceftobiprole was evaluated against 15 011 clinical isolates obtained from patients in Canadian hospitals between 2007 and 2009. All Staphylococcus aureus were susceptible to ceftobiprole (MIC(90)'s for methicillin-susceptible Staphylococcus aureus and methicillin-resistant Staphylococcus aureus of ≤ 1 μg/mL and 2 μg/mL, respectively). Ceftobiprole was active against penicillin-susceptible Streptococcus pneumoniae (MIC(90), ≤ 0.06 μg/mL), penicillin-resistant Streptococcus pneumoniae (MIC(90), 0.5 μg/mL), Streptococcus pyogenes (MIC(90), ≤ 0.06 μg/mL), Staphylococcus epidermidis (MIC(90), ≤ 1 μg/mL), and Enterococcus faecalis (MIC(90), ≤ 1 μg/mL). Over 90% of Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Citrobacter freundii, Proteus mirabilis, and Serratia marcescens isolates were inhibited by a ceftobiprole concentration of ≤ 1 μg/mL. Ceftobiprole was not active against extended-spectrum β-lactamase-producing Escherichia coli and K. pneumoniae. The in vitro activity of ceftobiprole versus Pseudomonas aeruginosa was similar to that of cefepime (MIC(90), 16 μg/mL). The broad spectrum of activity by ceftobiprole would support further study of this agent in the treatment of hospital-acquired infections.     

成都地区铜绿假单胞菌和鲍曼不动杆菌耐药性变化分析

目的了解成都中医药大学附属医院2012~2014年分离的铜绿假单胞菌及鲍曼不动杆菌耐药性的动态变化,为临床合理制订抗菌方案提供依据。方法对成都中医药大学附属医院2012年1月至2014年12月住院患者送检临床标本进行常规细菌培养,对临床分离病原菌采用梅里埃VITEK-2Compact系统进行细菌鉴定和药敏试验。结果铜绿假单胞菌对多种抗菌药物的耐药率呈逐年下降趋势,2014年下降尤为明显,对阿米卡星的最小抑菌浓度值呈逐年下降趋势。鲍曼不动杆菌对头孢唑啉、头孢曲松和呋喃妥因耐药率大于90.0%,对多种抗菌药物的耐药率2013年较2012年明显增加,但2014年与2013年相比增加不明显,甚至有所下降。结论在成都中医药大学附属医院,铜绿假单胞菌耐药性并非逐年加重,反而有所改善。鲍曼不动杆菌耐药情况较为严重,但未出现继续增加趋势,对两种细菌的耐药性应继续监测。     

In vitro activity of dalbavancin and telavancin against staphylococci and streptococci isolated from patients in Canadian hospitals: results of the CANWARD 2007-2009 study

Two novel lipoglycopeptides, dalbavancin and telavancin, and relevant comparative agents were tested for in vitro activity against clinical isolates of staphylococci and streptococci collected in the cross-Canada surveillance study, CANWARD, in 2007-2009. The rank order of potency (based on MIC(90) [μg/mL], i.e., the concentration of antimicrobial agent required to inhibit the growth of 90% of isolates tested) of glycopeptides against both Staphylococcus aureus and Staphylococcus epidermidis was dalbavancin (0.06 μg/mL) >telavancin (0.5 μg/mL) > vancomycin (1-2 μg/mL); concurrent susceptibility or resistance to oxacillin in staphylococci did not affect potency of glycopeptides. Dalbavancin and telavancin also demonstrated potent activity against Streptococcus pneumoniae, including penicillin-resistant isolates (MIC(90), ≤ 0.03 μg/mL; ≤ 0.06 μg/mL), and Streptococcus pyogenes (≤ 0.03 μg/mL; 0.06 μg/mL). Based on their robust in vitro activities, dalbavancin and telavancin have the potential to treat Gram-positive infections caused by methicillin-resistant Staphylococcus aureus and penicillin-resistant Streptococcus pneumoniae.     

鲍曼不动杆菌分泌物对铜绿假单胞菌及其生物膜的作用

目的探讨鲍曼不动杆菌培养上清对铜绿假单胞菌的浮游菌生长及生物膜形成的影响。方法收集鲍曼不动杆菌标准菌株(ATCC 19606和ATCC 1195)和临床菌株(AB23、AB39和AB53),提取6、12、16、24和48 h培养上清液。利用96孔板结合结晶紫染色法检测其培养上清液对铜绿假单胞菌标准菌株PAO1及其生物膜形成的影响;配制2×LB培养基,排除营养消耗对铜绿假单胞菌的影响;并进一步利用相对分子质量3 000蛋白质浓缩管对其培养上清液进行分离浓缩,初步探讨鲍曼不动杆菌培养上清液中有效成分的相对分子质量。结果 12~24 h内的鲍曼不动杆菌培养上清液,抑制铜绿假单胞菌增殖的效果最为显著,为便于操作,本实验采用16 h培养上清液进行后续实验。50%ATCC 1195和ATCC 19606培养上清液能显著抑制铜绿假单胞菌标准菌株PAO1浮游菌的增殖,可分别使其630 nm处的吸光度从0.688±0.014和0.692±0.014减少至0.431±0.023和0.428±0.020(t=16.780,P0.05;t=18.500,P0.05);且50%ATCC 1195和ATCC 19606培养上清液能显著抑制铜绿假单胞菌PAO1生物膜的形成,可使生物膜的形成量(A_(570 nm))从2.071±0.068和1.986±0.023减少至1.639±0.042和1.525±0.202(t=9.358,P0.05;t=3.924,P0.05);此外,与50%鲍曼不动杆菌培养上清液组相比,培养上清液中相对分子质量3 000的成分抑制作用显著,可使生物膜的形成量从1.177±0.040减少至1.056±0.030(t=4.192,P0.05),而3 000的成分并无抑制作用。结论鲍曼不动杆菌分泌物能有效抑制铜绿假单胞菌浮游菌的增殖和生物膜的形成,其有效蛋白质成分相对分子质量3 000。     

鲍曼不动杆菌及铜绿假单胞菌体外抗菌活性的分析及培养基的影响

目的了解当前鲍曼不动杆菌及铜绿假单胞菌的体外抗菌活性以及在低碱性氨基酸培养基中对碳青霉烯类抗菌药物最低抑菌浓度（MIC）的影响。方法收集临床分离的鲍曼不动杆菌47株、铜绿假单胞菌53株。按美国临床实验室标准化协会（CLSI）琼脂稀释法检测菌株对帕尼培南、亚胺培南、美罗培南、头孢他啶、头孢哌酮-舒巴坦、哌拉西林-他唑巴坦、头孢吡肟、左氧氟沙星、环丙沙星、阿米卡星10种抗菌药物的MIC;同法分别检测鲍曼不动杆菌、铜绿假单胞菌在低碱性氨基酸培养基和水解酪蛋白胨（MH）培养基上对帕尼培南、亚胺培南、美罗培南的敏感性。采用配对t检验比较2组试验结果。结果 47株鲍曼不动杆菌对亚胺培南、左氧氟沙星的耐药率最低,分别是17.10%和14.90%,哌拉西林-他唑巴坦耐药率高达78.70%。53株铜绿假单胞菌对阿米卡星的耐药率最低,为20.75%;头孢他啶的耐药率高达71.70%。在低碱性氨基酸的培养基中,鲍曼不动杆菌和铜绿假单胞菌对碳青霉稀类抗菌药物的敏感性差异有统计学意义（P〈0.05）。结论碳青酶烯类药物是治疗鲍曼不动杆菌引起的重症感染的重要药物。由于碱性氨基酸的浓度较高,鲍曼不动杆菌和铜绿假单胞菌对碳青霉烯类抗菌药物的敏感性在使用MH培养基检测时被低估。     

Analysis of 3789 in- and outpatient Escherichia coli isolates from across Canada--results of the CANWARD 2007-2009 study

Escherichia coli was the most commonly isolated pathogen in the Canadian Ward Surveillance Study 2007-2009 (3789 isolates). Susceptibility to cefazolin (34.1%), trimethoprim-sulfamethoxazole (73.8%), ciprofloxacin (78.4%), and levofloxacin (78.8%) was lowest. Susceptibility was above 90% for meropenem (100%), tigecycline (99.9%), piperacillin-tazobactam (97.6%), nitrofurantoin (96.9%), ceftazidime (95.6%), amoxicillin-clavulanate (94.9%), ceftriaxone (94.1%), cefoxitin (92.3%), and gentamicin (90.8%). Over the study period, there was a significant reduction in susceptibility to amoxicillin-clavulanate and trimethoprim-sulfamethoxazole for urinary tract isolates. Inpatient status was associated with greater resistance to nearly all antimicrobials including greater multidrug resistance (MDR). Increasing age was associated with resistance to fluoroquinolones, ceftriaxone, piperacillin-tazobactam, and MDR. Female gender was associated with susceptibility to fluoroquinolones and nitrofurantoin. In conclusion, greater antimicrobial resistance and MDR in E. coli were observed in inpatients, males, and with increasing age. The deterioration of susceptibility to trimethoprim-sulfamethoxazole continues with the greatest reduction in urinary isolates. Significant regional differences in resistance rates were apparent.     

Clinical predictors of Pseudomonas aeruginosa or Acinetobacter baumannii bacteremia in patients admitted to the ED

The identification of clinical characteristics that could identify patients at high risk for Pseudomonas aeruginosa or Acinetobacter baumannii bacteremia would aid clinicians in the appropriate management of these life-threatening conditions, especially in patients admitted to the emergency department (ED) with community-onset infections. To determine clinical risk factors for P. aeruginosa or A. baumannii bacteremia in patients with community-onset gram-negative bacteremia (GNB), a post hoc analysis of a nationwide bacteremia surveillance database including patients with microbiologically documented GNB was performed. Ninety-six patients with P. aeruginosa or A. baumannii bacteremia were compared with 1230 patients with Escherichia coli or Klebsiella pneumoniae bacteremia. A solid tumor or hematologic malignancy was more likely to be associated with P. aeruginosa or A. baumannii bacteremia, whereas concurrent neurologic disease was less frequently seen. In regards to the site of infection, pneumonia was more common in P. aeruginosa or A. baumannii bacteremia, whereas a urinary tract infection was less frequently seen. Factors associated with P. aeruginosa or A. baumannii bacteremia in multivariate analysis included pneumonia (odds ratio [OR], 3.60; 95% confidence interval [CI], 1.86-6.99), hematologic malignancy (OR, 2.71; 95% CI, 1.26-5.84), male sex (OR, 2.17; 95% CI, 1.31-3.58), solid tumor (OR, 1.89; 95% CI, 1.15-3.12), and health-care-associated infection (OR, 1.88; 95% CI, 1.48-2.41). Our data suggest that an initial empirical antimicrobial coverage of P. aeruginosa or A. baumannii bacteremia should be seriously considered in patients with pneumonia, a hematologic malignancy, solid tumor, or health-care-associated infection, when GNB is suspected, even in community-onset infections.     

Activity of meropenem with and without ciprofloxacin and colistin against Pseudomonas aeruginosa and Acinetobacter baumannii

Time-kill synergy studies showed that at 24 h, subinhibitory meropenem and ciprofloxacin concentrations of 0.06 to 128 and 0.03 to 32 microg/ml, respectively, showed synergy against 34/51 Pseudomonas aeruginosa strains; subinhibitory concentrations of meropenem (0.06 to 8 microg/ml) and colistin (0.12 to 1 microg/ml) showed synergy against 13 isolates. Subinhibitory meropenem and ciprofloxacin concentrations of 0.25 to 2 and 0.12 to 16 microg/ml, respectively, showed synergy against 18/52 Acinetobacter baumannii strains at 24 h. Subinhibitory meropenem and colistin concentrations of 0.03 to 64 and 0.06 to 8 microg/ml, respectively, showed synergy against 49 strains at 24 h.