Endemic carbapenem-resistant Acinetobacter species in Brooklyn, New York: citywide prevalence, interinstitutional spread, and relation to antibiotic usage.

Acinetobacter species are problematic nosocomial pathogens. In November 1997, pathogens isolated by microbiology laboratories were collected from 15 hospitals in Brooklyn, New York. Acinetobacter species accounted for 10% of gram-negative isolates. Only half of Acinetobacter species were susceptible to carbapenems; 11 hospitals had at least 1 isolate resistant to carbapenems. Other Acinetobacter susceptibility rates were as follows: polymyxin, 99%; amikacin, 87%; ampicillin/sulbactam, 47%; ceftazidime, 25%; and ciprofloxacin 23%. Overall, 10% were resistant to all commonly used antibiotics. Genetic analysis by use of pulsed-field gel electrophoresis of 12 carbapenem-resistant isolates revealed 4 strains that were recovered from >1 hospital, which suggests interinstitutional spread. Antibiotic usage data from 11 hospitals revealed that the use of third-generation cephalosporins was associated significantly with the percentage of carbapenem-resistant strains (P=.03). Resistant Acinetobacter species have become endemic in Brooklyn, New York. Citywide strategies that involve surveillance, infection-control practices, and the reduction of antibiotic usage may be necessary to control the spread of these pathogens.     

5155株医院获得性肺炎致病菌分布和抗菌素敏感性分析

目的 分析空军军医大学唐都医院医院获得性肺炎(hospital acquired pneumonia,HAP)致病菌分布及药敏试验结果,为经验性治疗HAP提供依据.方法 收集2017年01月至2019年12月我院临床送检呼吸道标本细菌培养结果、药敏试验结果.结果 共筛选合格菌株5155株,其中鲍曼不动杆菌最多(26.7...     

Rapid spread of carbapenem-resistant Klebsiella pneumoniae in New York City: a new threat to our antibiotic armamentarium

BACKGROUND: Carbapenem antibiotics are used to treat serious infections caused by extended-spectrum beta-lactamase-carrying pathogens. Carbapenem resistance has been unusual in isolates of Klebsiella pneumoniae. In this study, the prevalence and molecular epidemiologic characteristics of carbapenem-resistant K pneumoniae are analyzed, and the experience involving 2 hospital outbreaks is described. METHODS: A citywide surveillance study was conducted in hospitals in Brooklyn. An observational study involving subsequent outbreaks at 2 hospitals was undertaken. Isolates were genetically fingerprinted by ribotyping and were examined for the presence of KPC-type carbapenem-hydrolyzing beta-lactamases. RESULTS: Of 602 isolates of K pneumoniae collected during the citywide surveillance study, 45% had extended-spectrum beta-lactamases. Of the extended-spectrum beta-lactamase-producing isolates, 3.3% carried the carbapenem-hydrolyzing beta-lactamase KPC-2. Several isolates were reported by the clinical microbiology laboratories as being susceptible to imipenem. Although all the isolates were resistant using agar diffusion methods, minimal inhibitory concentrations of imipenem were substantially lower for several isolates using standard broth microdilution tests and were highly dependent on the inoculum used. Two hospitals experienced the rapid spread of carbapenem-resistant isolates involving 58 patients. Overall 14-day mortality for bacteremic patients was 47%. Most isolates belonged to a single ribotype. CONCLUSIONS: Carbapenem-resistant K pneumoniae isolates are rapidly emerging in New York City. The spread of a strain that possesses a carbapenem-hydrolyzing beta-lactamase has occurred in regional hospitals. Because these isolates are resistant to virtually all commonly used antibiotics, control of their spread is crucial. However, automated systems used for susceptibility testing may not accurately identify all these isolates, which will severely hamper control efforts.     

348株下呼吸道鲍曼不动杆菌耐药性及变迁分析

目的了解鲍曼不动杆菌及对碳青酶烯类抗生素耐药的鲍曼不动杆菌耐药性及变迁情况。方法采用纸片扩散法对2008～2010年从下呼吸道分离出的348株鲍曼不动杆菌进行药敏试验。结果鲍曼不动杆菌对头孢哌酮/舒巴坦(14.4%)耐药性最低,其次是碳青酶烯类药物亚胺培南(16.1%)和美罗培南(18.4%);对常用抗菌药物的耐药性均呈上升趋势。56株亚胺培南耐药鲍曼不动杆菌中,耐药率最高的是哌拉西林(100%),其次是替卡西林/克拉维酸、氨曲南和庆大霉素;耐药率最低的是米诺环素,其次为头孢哌酮/舒巴坦和环丙沙星。结论鲍曼不动杆菌耐药严重,加强耐药性监测,应根据药敏结果合理使用抗生素,以保护有限的抗生素资源。     

哌拉西林-舒巴坦等七种药物对非发酵菌体外抗菌活性的研究

目的 评价哌拉西林-舒巴坦等7种药物对非发酵菌的体外抗菌活性.方法 采用微量肉汤稀释法测定哌拉西林-舒巴坦对细菌的体外抗菌作用.结果 广州地区6家医院共收集菌株770株,其中铜绿假单胞菌216株,鲍曼不动杆菌242株,嗜麦芽窄食单胞菌100株,洋葱伯克霍尔德菌119株,黄杆菌属57株,产碱杆菌属36株.对所有铜绿假单胞菌,哌拉西林-舒巴坦的敏感性最高(71.9%),而亚胺培南、头孢吡肟、头孢他啶、头孢哌酮-舒巴坦敏感性均低于50%.对亚胺培南不敏感的铜绿假单胞菌,哌拉西林-舒巴坦敏感性仍可达55.8%.对碳青霉烯敏感的鲍曼不动杆菌,哌拉西林-舒巴坦和头孢哌酮-舒巴坦敏感性最高,分别为71.0%和73.0%.对嗜麦芽窄食单胞菌,26%和20%的菌株对哌拉西林-舒巴坦和哌拉西林-他唑巴坦的最低抑菌浓度(MIC)≤16 mg/L.对洋葱伯克霍尔德菌,69%的菌株对哌拉西林-舒巴坦的MIC≤16 mg/L.对黄杆菌属和产碱杆菌属,哌拉西林-舒巴坦、头孢哌酮-舒巴坦和哌拉西林他唑巴坦3种加酶复合制剂敏感性最高,分别为70.2%、63.2%、57.9%和94.4%、94.4%、91. 7%.结论 哌拉西林-舒巴坦对多种非发酵菌尤其是碳青霉烯不敏感的铜绿假单胞菌具有良好的体外抗菌活性.     

肺癌合并肺部感染的病原学和耐药性分析

目的了解铜陵地区肺癌合并肺部感染的病原学特征和耐药情况,为抗菌药物使用提供依据。方法收集3年所有肺癌合并肺部感染患者痰标本进行病原菌培养,采用K-B法进行药敏试验。结果共分离出各类致病菌142株,其中革兰阳性球菌占14.1%,革兰阴性杆菌占78.2%,真菌占7.8%。未检出对万古霉素耐药的葡萄球菌。肺炎克雷伯杆菌和大肠埃希菌对β-内酰胺酶抑制剂药物耐药率较低,对亚胺培南无耐药。铜绿假单胞菌对亚胺培南耐药率为25.0%,鲍曼不动杆菌对大多数抗菌药物耐药率在50%以上。结论肺癌合并肺部感染的致病菌以革兰阴性杆菌为主,且耐药现象严重。     

2009年山东大学附属省立医院细菌耐药性监测及分析

目的了解山东大学附属省立医院2009年临床分离菌株分布及耐药谱。方法收集山东大学附属省立医院2009年首次非重复分离株1 821株,细菌鉴定采用VITEK鉴定系统,药敏试验采用纸片扩散法,数据采用WHONET 5.4软件进行统计分析。结果大肠埃希菌和肺炎克雷伯菌对碳青霉烯类药物最敏感;柠檬酸杆菌属、沙雷菌属对碳青霉烯类药物敏感率较高,肠杆菌属和柠檬酸杆菌属对头孢西丁的耐药率分别为98.6%和85.7%,而沙雷菌属耐药率仅为30%;铜绿假单胞菌对哌拉西林/他唑巴坦、头孢吡肟、哌拉西林、头孢他啶、美罗培南、亚胺培南和头孢哌酮/舒巴坦较敏感,对其他药物敏感率均〈70%;鲍曼不动杆菌对亚胺培南、美罗培南敏感率为82.3%、73.2%,对头孢哌酮/舒巴坦耐药率为11.6%,对其他药物耐药率在15.0%~67.8%;葡萄球菌对万古霉素和利奈唑胺100%敏感,耐甲氧西林金黄色葡萄球菌和耐甲氧西林凝固酶阴性葡萄球菌检出率分别为45.0%和86.8%;屎肠球菌和粪肠球菌对万古霉素和利奈唑胺最敏感。结论肠杆菌科细菌对碳青霉烯类药物仍最为敏感,但不发酵糖菌对其耐药率升高;葡萄球菌属中均未发现耐万古霉素菌株。     

Nosocomial bloodstream infections caused by Acinetobacter species in United States hospitals: clinical features, molecular epidemiology, and antimicrobial susceptibility.

We examined the clinical and epidemiological features of nosocomial bloodstream infections (BSIs) caused by Acinetobacter species and observed from 1 March 1995 through 28 February 1998 at 49 United States hospitals (SCOPE National Surveillance Program). Acinetobacter species were found in 24 hospitals (49%) and accounted for 1.5% of all nosocomial BSIs reported. One hundred twenty-nine isolates were identified either as A. baumannii (n=111) or other Acinetobacter species (n=18). Patients with A. baumannii BSI, compared with patients with nosocomial BSI caused by other gram-negative pathogens, were more frequently observed in the intensive care unit (69% vs. 47%, respectively; P<.001; odds ratio [OR] 2.4; 95% confidence interval [CI] 1.6-3.7) and were more frequently receiving mechanical ventilation (58% vs. 30%, respectively; P<.001; OR 3.2; 95% CI 2.1-4.8). Crude mortality in patients with A. baumannii BSI was 32%. Molecular relatedness of strains was studied by use of polymerase chain reaction-based fingerprinting. Clonal spread of a single strain occurred in 5 hospitals. Interhospital spread of epidemic A. baumannii strains was not observed. The most active antimicrobial agents against A. baumannii (90% minimum inhibitory concentration values) were imipenem (1 mg/L; 100% of isolates susceptible), amikacin (8 mg/L; 96%), tobramycin (4 mg/L; 92%), and doxycycline (4 mg/L; 91%). Thirty percent of isolates were resistant to > or =4 classes of antimicrobials and were considered to be multidrug resistant.     

Prevalence and antibiotic susceptibility of Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae in Estonian intensive care units in comparison with European data

This prospective cohort study was performed from April to December 2003 for the purpose of collecting a maximum of 50 non-duplicate isolates of Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae from each of 4 ICUs to determine minimum inhibitory concentrations. The most prevalent species were Enterobacteriaceae (13%), K. pneumoniae and A. baumannii (both 12%). 60% of A. baumannii strains were susceptible to ampicillin/sulbactam and cefepime, 95% to meropenem and imipenem, and 75% to amikacin. 79% of P. aeruginosa strains were piperacillin/tazobactam, 58% ceftazidime, 81% meropenem, 72% imipenem, 69% ciprofloxacin and 97% amikacin susceptible. The susceptibility of K. pneumoniae to meropenem and imipenem was 99%, to ciprofloxacin was 91% and to amikacin was 98%. Gram-negative bacteria (especially K. pneumoniae and A. baumannii) were prevalent in our ICUs compared to other European studies. Carbapenem susceptibility of Estonian strains was higher, but P. aeruginosa sensitivity to ceftazidime was lower, compared to other EU countries.     

四川省二级综合医院耐碳青霉烯类鲍曼不动杆菌感染发生的相关危险因素分析

目的探讨四川省二级综合医疗机构耐碳青霉烯类鲍曼不动杆菌(carbapenem-resistant acinetobacter baumannii, CRAB)的耐药情况及相关临床危险因素。 方法采取回顾性病例-对照研究方法,调查2015年1月至2016年1月四川地区6家二级甲等综合医院鲍曼不动杆菌感染患者病例,根据药敏结果分为CRAB组和碳青霉烯敏感组(CSAB)。 结果共收集到非重复Ab菌株202株,其中CRAB 90株,耐药率40.1%。CRAB发生的4个独立危险因素为留置尿管(OR＝9.576,95%CI：4.964～18.474,P＝0.000)、中央静脉置管(OR＝2.707,95%CI：1.158～6.330,P＝0.022)、氟喹诺酮类(OR＝3.869,95%CI：1.603～9.377,P＝0.003)及碳青霉烯类抗菌药物(OR＝2.755,95%CI：1.164～6.521,P＝0.021)的使用。 结论二级综合医院CRAB感染的发生与侵袭性操作、氟喹诺酮类及碳青霉烯类等抗菌药物的选择压力有关。     

我院近3年下呼吸道革兰阴性杆菌耐药性监测

目的 调查我院近3年下呼吸道革兰阴性杆菌的耐药情况.方法 使用MIC法对我院下呼吸道感染住院患者的痰液标本中临床分离的926株革兰阴性杆菌进行药敏试验,并用WHONET 5.4软件进行数据分析.结果 926株革兰阴性杆菌中最常见的菌种依次为大肠埃希菌(29.7%)、肺炎克雷伯菌(23.7%)、铜绿假单胞菌(14.3%)、鲍曼不动杆菌(12.1%).大肠埃希菌、肺炎克雷伯菌对多黏菌素B、亚胺培南、美罗培南和咪诺环素保持高度敏感,耐药菌率在10%以内,对阿米卡星、哌拉西林/三唑巴坦、头孢哌酮/舒巴坦、头孢他啶及头孢匹肟的耐药率为30%以内,对其余所检测药物的耐药率均在30%以上.铜绿假单胞菌对多黏菌素B和咪诺环素;而亚胺培南,美罗培南、哌拉西林/三唑巴坦,头孢哌酮/舒巴坦和阿米卡星耐药率低于30%{鲍曼不动杆菌耐药情况比较严重,只有多黏菌素B、头孢哌酮/舒巴坦高度敏感,耐药率在10%以内,对亚胺培南和美罗培南的耐药率在20%以内,对其余所检测药物的耐药率均在30%到60%以上.结论 本研究结果对我院革兰阴性杆菌感染的经验用药治疗有重要参考价值.     

梅州地区临床分离耐碳氢霉烯类鲍曼不动杆菌的耐药机制及分子流行病学研究

目的 了解梅州地区临床分离的耐碳青霉烯类鲍曼不动杆菌的耐药性,探讨其耐药机制及分子流行病学特征。方法 收集梅州地区5所医院2012年1～12月临床分离的非重复耐碳青霉烯类鲍曼不动杆菌210株,采用K-B法检测药敏性,改良Hodge试验筛选耐碳青霉烯表型,PCR扩增IMP、VIM、OXA-23、OXA-24、OXA-51和OXA-58型碳氢霉烯酶基因,并测序。应用ERIC-PCR分型及同源性分析。结果 药敏结果显示,17种药物除多粘菌素B耐药率为0.48%外,其他药敏耐药率都高于60%;改良Hodge试验阳性菌株163株(77.62%)。扩增结果显示Bla-OXA-51的检出率为最高为94.29%(198/210),Bla-OXA-23的检出率次之为78.57%(165/210),Bla-VIM的检出率为4.29%(9/210),Bla-IMP、Bla-OXA-24、Bla-OXA-58均未被检出。210株菌株分为7个ERIC基因型,其中A型97株,B型44株,H型25株,为主要的流行克隆株。结论 梅州地区临床分离的耐碳青霉烯类鲍曼不动杆菌耐药十分严重;产OXA-51、OXA-23和VIM型碳氢霉烯酶是本地区鲍曼不动杆菌对碳青霉烯类药物耐药的重要机制,且耐碳青霉烯类鲍曼不动杆菌存在克隆的流行。     

下呼吸道感染患儿肺泡灌洗液的病原菌分布及其耐药模式

目的:了解2016年至2018年我国下呼吸道感染患儿的肺泡灌洗液病原菌分布及其对抗菌药物的耐药情况。方法:采集2016年1月至2018年12月10家三级医院收治的年龄<18岁的下呼吸道感染患儿的肺泡灌洗液标本,培养分离获得病原菌。采用纸片扩散法或最低抑菌浓度法对分离菌株进行药物敏感试验,分析病原菌的分布情况,以及菌株来...     

Epidemiology of nosocomial pneumonia in infants after cardiac surgery

BACKGROUND: The pattern of nosocomial pneumonia (NP) in infants in a pediatric surgical ICU after cardiac surgery may differ from that seen in adult ICUs. STUDY OBJECTIVES: The primary aim of this study was to describe the epidemiology of NP in infants after cardiac surgery and, secondarily, to describe the changes of the distribution and antibiotic resistance of the pathogen during the last 3 years. METHODS: Data were collected between June 1999 and June 2002 from 311 consecutive infants who underwent open-heart surgery in our hospital. We retrospectively analyzed the distribution and antibiotic resistance pattern of all the pathogenic microbial isolates cultured from lower respiratory tract aspirations. RESULTS: Of 311 infants, 67 patients (21.5%) acquired NP after cardiac surgery. The incidence of NP was more frequently associated with complex congenital heart defect (CHD) compared to simple CHD (43% vs 15.9%, chi(2) = 22.47, p < 0.0001). The proportion of late-onset NP was higher in patients with complex CHD (chi(2) = 6.02, p = 0.014). A total of 79 pathogenic microbial strains were isolated. Gram-negative bacilli (GNB) were the most frequent isolates (68 isolates, 86.1%), followed by fungi (6 isolates, 7.6%) and Gram-positive cocci (5 isolates, 6.3%). The main GNB were Acinetobacter baumanii (11 isolates, 13.9%), Pseudomonas aeruginosa (10 isolates, 12.7%); other commonly seen GNB were Flavobacterium meningosepticum (7 isolates, 8.9%), Klebsiella pneumoniae (7 isolates, 8.9%), Escherichia coli (6 isolates, 7.6%), and Xanthomonas maltophilia (5 isolates, 6.2%). The most commonly seen Gram-positive cocci were Staphylococcus aureus (2 isolates, 2.5%) and Staphylococcus epidermidis (2 isolates, 2.5%). The frequent fungi were Candida albicans (5 isolates, 6.3%). Most GNB were sensitive to cefoperazone-sulbactum, piperacillin-tazobactam, imipenem, ciprofloxacin, amikacin. The bacteria producing extended spectrum beta-lactamases were mainly from K pneumoniae and E coli; the susceptibility of ESBL-producing strains to imipenem was 100%. There were one case of methicillin-resistant S aureus (MRSA) and 1 case of methicillin-resistant S epidermidis; their susceptibility to vancomycin, gentamycin, and ciprofloxacin were 100%. From 1999 to 2002 in infants with NP after open-heart surgery, there was a trend of increasing frequency of multiresistant GNB such as A baumanii, P aeruginosa, and K pneumoniae. However, no remarkable changes of distribution were found in Gram-positive cocci and fungi in the 3-year period. Early onset episodes of NP were frequently caused by Haemophilus influenzae, methicillin-sensitive S aureus, and other susceptible Enterobacteriaceae. Conversely, in patients who acquired late-onset NP, P aeruginosa, A baumannii, other multiresistant GNB, MRSA, and fungi were the predominant organisms. CONCLUSIONS: The pattern of pathogens and their antibiotic-resistance patterns in NP in infants after cardiac surgery had not shown an increasing prevalence of Gram-positive pathogens as reported by several adult ICUs. GNB still remained the most common pathogens during the last 3 years in our hospital. There was a trend of increasing antibiotic resistance in these isolates.     

In vitro activity of colistin or sulbactam in combination with fosfomycin or imipenem against clinical isolates of carbapenem-resistant Acinetobacter baumannii producing OXA-23 carbapenemases

This study investigated the in vitro activity of colistin or sulbactam in combination with fosfomycin or imipenem against eight strains of carbapenem-resistant A. baumannii (CRAB). The eight CRAB clinical isolates were collected from hospitalized patients admitted to Songklanagarind Hospital in southern Thailand during January-December 2008. The isolates were divided into 4 different patterns of clonal relationships using the Repetitive Extragenic Palindromic-Polymerase Chain Reaction method (REP-PCR). The in vitro activity of combination antibacterial agents against theses isolates were determined by chequerboard and time-kill methods. All isolates producing OXA-23 carbapenemases were universally susceptible to colistin but intermittently susceptible to other antimicrobial agents. A chequerboard assay showed the synergistic effects of sulbactam plus fosfomycin and colistin plus fosfomycin in 75% and 12.5% of isolates, respectively. Sulbactam at a concentration of 1 x MIC plus fosfomycin at 1 x MIC or at 1/4 x MIC showed synergism in 75% and 37.5% of clinical isolates, respectively. Bactericidal activity was observed for up to 12 hours of incubation. There was no synergism between colistin and sulbactam, sulbactam and imipenem, and colistin and imipenem, against the tested isolates. Combined use of sulbactam and fosfomycin may provide an alternative therapeutic option for CRAB infections.     

老年患者医院获得性肺炎的病原菌耐药性分析

目的:了解县级医院老年患者医院获得性肺炎的病原菌种类分布及耐药特征,为临床科室预防与治疗老年患者医院获得性肺炎选择抗生素提供参考指南。方法:对255例年龄≥60岁的获得性肺炎患者原始病历进行逐份查阅统计;痰液或下呼吸道吸取物的无菌采集、细菌培养、种型鉴定按照临床微生物检验的技术路线进行实验操作;药敏检测采用WHO规定的KB法,抑菌圈测量,敏感、中介、耐药数据比照CLSI最新规则评价;数据统计学采用WHONET 5.6软件处理,实验条件遵照室内质量控制条例进行标准化管理。结果:279株病原菌中,位于前6位的细菌是:肺炎克雷伯菌(24.7%)、铜绿假单胞菌(15.4%)、金黄色葡萄球菌(14.7%)、鲍曼不动杆菌(13.3%)、白色假丝酵母菌(7.5%)、大肠埃希菌(5.7%)。药物检测发现:大部分病原菌对临床抗菌药物产生了严重的抗药性:MRSA检出率为46.3%,产ESBLs大肠埃希菌和肺炎克雷伯菌检出率为47.1%,耐亚胺培南铜绿假单胞菌和鲍曼不动杆菌分别达到25.6%、32.4%;革兰阴性杆菌耐药率20%的抗菌药物有阿米卡星、头孢哌酮/舒巴坦,耐药率最高的是磺胺甲噁唑/甲氧苄啶,均65%;但肠杆菌科菌株对碳青霉烯类药物100%敏感;金黄色葡萄球菌对糖肽类药物100%敏感。结论:老年患者医院获得性肺炎的病原菌耐药性上升趋势明显,务必采取有效的治理措施,严格医师抗生素处方管理,致力于改变细菌耐药性快速上升的不良现象。     

急诊重症监护病房革兰阴性杆菌感染的临床调查

目的明确急诊重症监护病房（EICU）获得性革兰阴性菌感染的病原分布概况和抗菌药物的敏感性，指导临床经验性使用抗菌药物。方法自2002年4月-2005年12月，对我院急诊科重症监护病房患者院内获得性革兰阴性菌感染及其抗菌药物的敏感性进行回顾性调查。结果院内获得性细菌感染革兰阴性菌占46．95％，主要为铜绿假单胞菌、鲍曼不动杆菌、阴沟肠杆菌、大肠埃希菌、克雷伯菌属菌株。G-菌仍对亚胺培南保持着较高的敏感率。结论革兰阴性菌仍然为常见的医院感染致病菌，根据细菌病原学及抗菌药物敏感性的临床资料，合理选择经验性抗菌药物，减少耐药菌的出现。     

Update on Pseudomonas aeruginosa and Acinetobacter baumannii infections in the healthcare setting

PURPOSE OF REVIEW: Infections with Pseudomonas aeruginosa and Acinetobacter baumannii are of great concern for hospitalized patients, especially with multidrug-resistant strains. This review focuses on recent data that may help us to understand the emergence, spread, and persistence of antibiotic resistance, and summarizes the optional treatment feasible for these resistant bacteria. RECENT FINDINGS: Multidrug-resistant P. aeruginosa and A. baumannii are increasingly causing nosocomial infections; multidrug-resistant clones are spreading into new geographic areas, and susceptible strains are acquiring resistance genes. New extended-spectrum beta-lactamases and carbapenemases are emerging, leading to pan-resistant strains. Current studies focus on the effect of antibiotics on gene expression in P. aeruginosa biofilms and their contribution to resistance to therapy. Treatment options for multidrug-resistant P. aeruginosa and A. baumannii infections are limited in most cases to carbapenems. Sulbactam is a treatment option for pan-resistant A. baumannii, and or renewed use of an old drug, colistin, is being entertained for pan-resistant A. baumannii and P. aeruginosa. Immunotherapy is a promising new modality being explored. Prevention of emergence of resistance through combination therapy and pharmacokinetic strategies are studied. SUMMARY: The emergence and spread of multidrug-resistant P. aeruginosa and A. baumannii and their genetic potential to carry and transfer diverse antibiotic resistance determinants pose a major threat in hospitals. The complex interplay of clonal spread, persistence, transfer of resistance elements, and cell-cell interaction contribute to the difficulty in treating infections caused by these multidrug-resistant strains. In the absence of new antibiotic agents, new modalities of treatment should be developed.     

PCR identification and automated ribotyping of Pseudomonas aeruginosa clinical isolates from intensive care patients

Nosocomial isolates of Pseudomonas aeruginosa exhibit high rates of resistance to antibiotics, and are often multidrug resistant. P. aeruginosa clinical isolates (n = 56) were obtained from ICU patients in a hospital in Pakistan over a 3-y period. Antimicrobial susceptibility of the 56 P. aeruginosa clinical isolates was investigated using 7 antibiotics and the resistance rates were as follows: aztreonam (68% resistant), ceftazidime (67%), imipenem (66%), ofloxacin (59%), amikacin (56%), gentamicin (44%), and piperacillin-tazobactam (27%) (p < 0.01). In addition, 55% of the P. aeruginosa clinical isolates were resistant to 4 or more antibiotics. Imipenem-resistant strains were frequently associated with ceftazidime, ofloxacin, aztreonam, and more strikingly, amikacin resistance (p < 0.05). PCR (using P. aeruginosa-specific primers VIC1 + VIC2 and P1 + P2, respectively) was highly specific and sensitive, and was positive for all 56 P. aeruginosa isolates tested. Automated ribotyping was used to investigate the clonal diversity of the 56 P. aeruginosa isolates. Automated ribotyping indicated that the clinical isolates were clonally related and could be clustered into 4 major ribogroups based on their similarity index, with ribogroup II being the dominant one. The P. aeruginosa isolates in ribogroup II were correlated with their antibiotic resistance pattern and, interestingly, there seemed to be a gradual acquisition of multiple antibiotic resistance associated with the isolates within this group over time. The ribotyping data, together with the antibiotic resistance profile, provide valuable molecular epidemiology information for the control of hospital-acquired P. aeruginosa infections.