Emergence of antibiotic resistance amongst hospital-acquired urinary tract infections and pharmacokinetic/pharmacodynamic considerations

Bacterial urinary tract infections (UTIs) are frequent infections in the nosocomial setting. Nosocomial UTIs are almost exclusively complicated UTIs, although the complicating factors may be very heterogenous. The bacterial spectrum of nosocomial UTIs is broad and antibiotic resistance is common. The results of international and national surveillance studies on the bacterial spectrum and antibiotic resistance of nosocomial uropathogens are provided. The treatment of nosocomial UTIs encompasses treatment of the complicating factors as well as antimicrobial chemotherapy. At least in serious UTIs, adequate initial antibiotic therapy results in lower mortality. Therefore, the initial antibiotic regimen must provide sufficient antibiotic cover. However, this can only be achieved if the bacterial spectrum and antibiotic resistance patterns of uropathogens in the institution are followed continuously. Provisional microbiological findings, such as reports on Gram stain or certain biochemical results, can lead to early stratification of pathogens and allow more tailored empiric antibiotic therapy. Antibiotic therapy of nosocomial UTIs has to consider two different aspects: (1) therapeutic success in the individual patient; and (2) prevention of emergence of antibiotic-resistant mutants. The emergence of resistance can possibly be lowered by adequate drug selection and dosing. Increasing antibiotic resistance requires more prudent use of antimicrobial drugs.     

Favorable impact of a multidisciplinary antibiotic management program conducted during 7 years.

OBJECTIVE: To evaluate the impact of an interventional multidisciplinary antibiotic management program on expenditures for antibiotics and on the incidence of nosocomial infections caused by Clostridium difficile and antibiotic-resistant pathogens during 7 years. DESIGN: Prospective study with comparison with preintervention trends. SETTING: University-affiliated teaching hospital. PATIENTS: All adult inpatients. INTERVENTION: A multidisciplinary antibiotic management program to minimize the inappropriate use of third-generation cephalosporins was implemented in 1991. Its impact was evaluated prospectively. The incidence of nosocomial C. difficile and resistant Enterobacteriaceae infections as well as the rate of vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) were compared with those of National Nosocomial Infections Surveillance System hospitals of similar size. RESULTS: Following implementation of the program, there was a 22% decrease in the use of parenteral broad-spectrum antibiotics (P < .0001) despite a 15% increase in acuity of patient care during the following 7 years. Concomitantly, there was a significant (P = .002) decrease in nosocomial infections caused by C. difficile and a significant (P = .02) decrease in nosocomial infections caused by resistant Enterobacteriaceae. The program also appeared to have a favorable impact on VRE rates without a sustained impact on MRSA rates. CONCLUSION: These results suggest that an ongoing multidisciplinary antibiotic management program may have a sustained beneficial impact on both expenditures for antibiotics and the incidence of nosocomial infection by C. difficile and resistant bacterial pathogens.     

医院内、外感染大肠埃希菌、肺炎克雷伯菌药物敏感性分析

目的 分析比较天津市临床分析的大肠埃希菌、肺炎克雷伯菌对常用抗生素的耐药情况。方法 搜集天津市8所大型综合医院2001年8月～2002年3月临床分析的421株大肠埃希菌和418株肺炎克雷伯菌，进行药物敏感性测定，同时判断菌株来源是否为医院感染的患者。结果 医院感染株对绝大部分抗生素的耐药率都高于社区感染的菌株，其结果有统计学意义，医院感染株ESBLs产生比例也高于社区感染株，其结果存在统计学差异，亚胺培南、阿米卡星、头孢他啶对上述两菌仍有良好的抗菌活性；对喹诺酮类、环丙沙星耐药率，大肠埃希菌医院内、外分别为71．9％和61．1％，对肺炎克雷伯分别为32．2％和21．8％，两者之间无统计学意义}大肠埃希菌对庆大霉素耐药率医院内、外分别为60．3％和48．1％，两者之间无统计学意义。结论 医院感染分离株耐药率高于医院外分离株，应引起经验性使用抗生素的注意，对环丙沙星和庆大霉素的耐药可能与环境因素相关。     

A longitudinal study of Acinetobacter in three Australian hospitals

Acinetobacter has recently risen in prominence as a nosocomial pathogen, particularly due to increasing antibiotic resistance. The aim of this study was to describe changes in rates and antibiotic susceptibility patterns of Acinetobacter in three Melbourne hospitals. This was a retrospective review of microbiology records over five years. The rates of new clinical isolates of Acinetobacter per 10 000 discharges per quarter were calculated. Other information collected included antibiotic susceptibility patterns, age, gender, length of stay and ward [intensive care unit (ICU) or non-ICU]. Rates increased substantially at two hospitals, but not at the third. Increasing numbers at one hospital were associated with antibiotic resistance. Most first isolates were identified while the patient was in the ICU. Many isolates were from respiratory specimens, although a significant proportion was from blood. This study documents the establishment of Acinetobacter as a nosocomial pathogen in two Melbourne hospitals and serves as a warning for the future.     

Antibiotic resistance among E. coli isolates from urinary tract infections (1999-2000): a multicenter study

E. coli is the most frequently isolate species in community as well as in nosocomial acquired urinary tract infections (UTI). Trimethoprim-sulfamethoxazole (TMP-SMX), is commonly used as empiric treatment for managing uncomplicated UTI whereas the rate of resistance to amoxicilline is increasing. A multicentric retrospective study was conducted from January 1st 1999 to December 31st 2000 to evaluate the prevalence of E. coli isolates from UTI and to guide empiric therapies. Among 6994 urinary isolates, 62.6% were resistant to amoxicilline, this rate fell to 33.6% when amoxicilline was associated to clavulanic acide, 2.7% were producing extended spectrum b-lactamases (BLSE), higher than reported in France and USA. 37.3% were resistant to TMP-SMX. The high prevalence of antimicrobial resistance among UTI E. coli isolates emphasizes the necessity to review the empiric therapies. Fluoroquinolones can be considered as an alternative therapy according to their excellent tissue penetration and their wide spectrum of activity.     

阴沟肠杆菌超广谱β-内酰胺酶检测及耐药性分析

目的 监测阴沟肠杆菌医院感染菌株ESBLs的产生及其对常用抗菌药物的耐药性。方法 采用5种底物的“双纸片协同试验”检测ESBLs;体外药敏试验采用K－B法;实验数据处理使用WHONET－5软件。结果 在本组样本的47株阴沟肠杆菌临床分离株中,ESBLs的检出率为38．3％;未发现亚胺培南耐药株,阿米卡星和环丙沙星的耐药率依次为17．0％、29．8％;产ESBLs和不产ESBLs菌株间的耐药率存在显著差异。结论 ESBLs是造成本地区阴沟肠杆菌严重耐药的主要原因之一;阴沟肠杆菌感染的治疗应首选亚胺培南;其次为阿米卡星和环丙沙星。     

Antibiotic-stewardship practices at top academic centers throughout the United States and at hospitals throughout Massachusetts.

OBJECTIVE: Improvements in antibiotic prescribing to reduce bacterial resistance and control hospital costs is a growing priority, but the way to accomplish this is poorly defined. Our goal was to determine whether certain antibiotic stewardship interventions were universally instituted and accepted at top US academic centers and to document what interventions, if any, are used at both teaching and community hospitals within a geographic area. DESIGN: Two surveys were conducted. In survey 1, detailed phone interviews were performed with the directors of antibiotic stewardship programs at 22 academic medical centers that are considered among the best for overall medical care in the United States or as leaders in antibiotic stewardship programs. In survey 2, teaching and community hospitals throughout Massachusetts were surveyed to ascertain what antibiotic oversight program components were present. RESULTS: In survey 1, each of the 22 participating hospitals had instituted interventions to improve antibiotic prescribing, but none of the interventions were universally accepted as essential or effective. In survey 2, of 97 surveys that were mailed to prospective participants, a total of 54 surveys from 19 teaching hospitals and 35 community hospitals were returned. Ninety-five percent of the teaching hospitals had a restricted formulary, compared with 49% of the community hospitals, and 89% of teaching hospitals had an antibiotic approval process, compared with 29% of community hospitals. CONCLUSION: There was great variability among the approaches to the oversight of antibiotic prescribing at major academic hospitals. Antibiotic management interventions were lacking in more than half of the Massachusetts community hospitals surveyed. More research is needed to define the best antibiotic stewardship interventions for different hospital settings.     

Adherence to empiric antibiotic therapy guideline in a referral teaching hospital, Tehran, Iran

Antibiotic guidelines have proven to be a simple and effective intervention to guide the choice of appropriate empiric antibiotic regimens. The goals of this study were to evaluate adherence to guidelines and streamlining of antibiotics. Hospital records of hospitalized patients in infectious diseases ward Imam Khomeini Hospital, Tehran, Iran, from May 2008 to September 2009 were reviewed. Adherence to guideline was defined as the use of empiric antibiotic in accordance with the clinical diagnosis and local guideline recommendations. In this study, 528 patients with a confirmed infectious disease diagnosis were considered for analysis. The four most frequent diagnoses were skin and soft tissue infections, tuberculosis, respiratory tract infections, and HIV associated opportunistic infections. The most frequent prescribed antibiotic was ceftriaxone. Overall adherence to guideline was 70.8% and the adherence for the most frequent diagnosis was 68%. Frequency of compatibility with the guidelines for were administrated regimes on the basis of drug selection, dosage form and drug dosing were 86.2%, 97% and 84.7%, respectively. The mean lag time between patients' hospital admission and starting empiric therapy was 1.69 ± 4.9 days. In general, physicians' adherence with guidelines for empiric antibiotic therapy was high in infectious disease ward with a justified delay. Larger studies are required to establish these conclusions.     

Appropriate antimicrobial treatment in nosocomial infections-the clinical challenges

Resistance to antimicrobial agents is emerging in a wide variety of pathogens, particularly those that cause nosocomial infections. As a consequence of this increasing resistance, morbidity and mortality in nosocomial infections is also increasing. It is therefore critical to treat nosocomial infections appropriately by starting antimicrobial treatment early in the course of infection, using the correct agent, at the most appropriate dose, and for an adequate duration. Indeed, early 'appropriate' antibiotic prescribing has been shown significantly to reduce mortality, length of intensive care unit and hospital stay and overall costs. Early use of the correct antibiotic at the appropriate dose and for an adequate duration are key to initial appropriate antibiotic prescribing. Choosing the right antibiotic depends mainly on the likely pathogen(s) and the expected local susceptibility patterns. Selection of appropriate antimicrobial therapy requires a thorough understanding of the likely microbial cause of the infection, including local susceptibility patterns, as well as the properties of the antimicrobials available for treating these infections, namely spectrum of activity and potency (including activity versus known resistance mechanisms), pharmacokinetic profile and tolerability and safety. This review, based on a series of presentations at the 5th International Conference of the Hospital Infection Society (Edinburgh, 2002) examines the importance of appropriate antimicrobial therapy in nosocomial infections, and provides guidance on how to achieve this.     

Aktuelle Daten und Trends zur Antibiotikaresistenzentwicklung von Clostridium difficile

Clostridium difficile is the most common pathogen causing antibiotic-associated diarrhea. Antibiotic therapy also favors the development and the epidemic spreading of multiresistant strains. In this present retrospective study clinical isolates from the University of Saarland Medical Center and of other German isolate referring hospitals were characterized by genotyping and antibiotic resistance testing. The most prevalent strains were ribotypes 001 (18%), 014 (16%) and 027 (15%). Sensitivity to metronidazol and vancomycin was demonstrated for 99.7?% of the clinical isolates independent of the genotype. Of the isolates 96?% were rifampicin susceptible; however, significantly more cases of rifampicin resistance were found among 027 strains (12?%). Of the isolates 58% were clarithromycin sensitive and 57% moxifloxacin sensitive. In contrast to the various sporadic genotypes the majority of epidemic strains were macrolide or fluoroquinolone resistant (001, 027 and 078); however, discrimination between epidemic strains by antibiotic resistance profiles could not be discerned. A combination of consistent adherence to hygiene management guidelines and to a prudent and rational use of antimicrobials (antibiotic stewardship) may help to reduce the total number of C. difficile infections (CDI) and also the selection of multiresistant strains. On the other hand in the collection of isolates the sensitivity towards the standard oral antibiotic agents used for C. difficile treatment appears to be unimpaired by the global changes of C. difficile resistant profiles.     

Nosocomial infections in combined medical-surgical intensive care units in the United States.

OBJECTIVE: To describe the epidemiology of nosocomial infections in combined medical-surgical (MS) intensive care units (ICUs) participating in the National Nosocomial Infection Surveillance (NNIS) System. DESIGN: Analysis of surveillance data on 498,998 patients with 1,554,070 patient-days, collected between 1992 and 1998 from 205 MS ICUs following the NNIS Intensive Care Unit protocol, representing 152 participating NNIS hospitals in the United States. RESULTS: Infections at three major sites represented 68% of all reported infections (nosocomial pneumonia, 31%; urinary tract infections (UTIs), 23%; and primary bloodstream infections (BSIs), 14%: 83% of episodes of nosocomial pneumonia were associated with mechanical ventilation, 97% of UTIs occurred in catheterized patients, and 87% of primary BSIs in patients with a central line. In patients with primary BSIs, coagulase-negative staphylococci (39%) were the most common pathogens reported; Staphylococcus aureus (12%) was as frequently reported as enterococci (11%). Coagulase-negative staphylococcal BSIs were increasingly reported over the 6 years, but no increase was seen in candidemia or enterococcal bacteremia. In patients with pneumonia, S. aureus (17%) was the most frequently reported isolate. Of reported isolates, 59% were gram-negative bacilli. In patients with UTIs, Escherichia coli (19%) was the most frequently reported isolate. Of reported isolates, 31% were fungi. In patients with surgical-site infections, Enterococcus (17%) was the single most frequently reported pathogen. Device-associated nosocomial infection rates for BSIs, pneumonia, and UTIs did not correlate with length of ICU stay, hospital bed size, number of beds in the ICU, or season. Combined MS ICUs in major teaching hospitals had higher device-associated infection rates compared to all other hospitals with combined medical-surgical units. CONCLUSIONS: Nosocomial infections in MS ICUs at the most frequent infection sites (bloodstream, urinary, and respiratory tract) almost always were associated with use of an invasive device. Device-associated infection rates were the best available comparative rates between combined MS ICUs, but the distribution of device-associated rates should be stratified by a hospital's major teaching affiliation status.     

Changing pattern of antibiotic resistance in methicillin-resistant Staphylococcus aureus from German hospitals.

OBJECTIVE: To investigate the background of changes of resistance phenotypes in methicillin-resistant Staphylococcus aureus (MRSA) from nosocomial infections in German hospitals by molecular typing and identification of particular resistance genes. METHODS: Isolates from the network for monitoring the spread of MRSA in Germany were subjected to quantitative susceptibility testing, to molecular typing, and to polymerase chain reaction identification of resistance genes. PARTICIPANTS: The network consists of 175 German clinical microbiological laboratories collaborating with the German Reference Center for Staphylococci, which performs typing of staphylococcal isolates from nosocomial infections and data analysis. RESULTS: During the past 5 years, MRSA susceptible to other antibiotics such as oxytetracycline, erythromycin, and gentamicin became more frequent. The proportion of epidemic MRSA clones that had been disseminated in the past and that exhibited broad resistance phenotypes decreased, whereas the proportion of recently emerging MRSA carrying only a few other resistance determinants has increased (1994, 11.5%; 1998, 39%). CONCLUSIONS: The changing pattern of resistance phenotypes of MRSA from nosocomial infections in Germany is mainly due to the spread of recently emerging epidemic strains that are less frequently resistant to antibacterials other than oxacillin. The observed changes cannot simply be attributed to overall antibiotic consumption.     

Controlling use of antimicrobials in a community teaching hospital.

OBJECTIVE: To test the hypothesis that antibiotic use could be controlled or improved in a community teaching hospital, with improvement defined as reductions in overall use, overall cost, and antimicrobial resistance. DESIGN: Interventional study with historical comparison. SETTING: A not-for-profit, 900-bed community general hospital with residents in medicine, surgery, obstetrics-gynecology, and psychiatry. PARTICIPANTS: Physicians who requested any of the targeted antibiotics. INTERVENTIONS: Three categories of inpatient antibiotic orders were monitored beginning in April 2001: conversion from intravenous to oral administration for selected highly bioavailable antimicrobials, cessation of perioperative prophylaxis within 24 hours for patients undergoing clean and clean-contaminated surgery, and consultation with an infectious diseases physician before continuing administration of selected drugs beyond 48 hours. Data were analyzed after the first 33 months. Patient outcomes were reviewed during the hospital stay and at readmission if it occurred within 30 days after discharge. RESULTS: From April 2001 through December 2003, a total of 1426 requests for antimicrobial therapy met criteria for intervention. Overall physician compliance with the program was 76%, ranging from 57% for perioperative prophylaxis to 92% for intravenous to oral conversion. Antimicrobial costs per patient-day decreased by 31%, from 13.67 US dollars in 2000 (before program implementation) to 9.41 US dollars in 2003. Total savings in acquisition costs were 1,841,203 US dollars for the 3-year period. Resistance to numerous drugs among Klebsiella pneumoniae isolates was also significantly reduced. CONCLUSIONS: A program to improve the use of antibiotics in a community hospital was successful in reducing overall use, overall cost, and antimicrobial resistance.     

Favorable impact of an infection control network on nosocomial infection rates in community hospitals.

OBJECTIVE: To describe an infection control network (the Duke Infection Control Outreach Network [DICON]) and its impact on nosocomial infection rates in community hospitals. DESIGN: Prospective cohort study of rates of nosocomial infections and exposures of employees to bloodborne pathogens in hospitals during the first 3 years of their affiliation with DICON. Attributable cost and mortality estimates were obtained from published studies.Setting. Twelve community hospitals in North Carolina and Virginia. RESULTS: During the first 3 years of hospital affiliation with DICON, annual rates of nosocomial bloodstream infections at study hospitals decreased by 23% (P = .009). Annual rates of nosocomial infection and colonization due to methicillin-resistant Staphylococcus aureus decreased by 22% (P = .002), and rates of ventilator-associated pneumonia decreased by 40% (P = .001). Rates of exposure of employees to bloodborne pathogens decreased by 18% (P = .003). CONCLUSIONS: The establishment of an infection control network within a group of community hospitals was associated with substantial decreases in nosocomial infection rates. Standard surveillance methods, frequent data analysis and feedback, and interventions based on guidelines and protocols from the Centers for Disease Control and Prevention were the principal strategies used to achieve these reductions. In addition to lessening the adverse clinical outcomes due to nosocomial infections, these reductions substantially decreased the economic burden of infection: the decline in nosocomial bloodstream infections and ventilator-associated pneumonia alone yielded potential savings of 578,307 US dollars to 2,195,954 US dollars per year at the study hospitals.     

Resistance to imipenem among selected gram-negative bacilli in the United States.

OBJECTIVES: Identification of imipenem resistance among selected gram-negative bacilli, especially Pseudomonas aeruginosa and Enterobacter species. METHODS: We analyzed 1986-1990 National Nosocomial Infection Surveillance (NNIS) data from 3,316 P aeruginosa isolates and 1,825 Enterobacter species isolates for which susceptibility results to imipenem were reported. RESULTS: For P aeruginosa, 11.1% of the isolates were resistant to imipenem; 16.1% were either intermediate-susceptible or resistant to the drug. A logistic regression model found that resistance was more common among P aeruginosa isolated from the respiratory tract, patients in intensive care units, and in teaching hospitals. Additionally, resistance to imipenem increased by 25% in teaching hospitals from 1986-1988 to 1989-1990. For Enterobacter species, 1.3% of the isolates were resistant to imipenem; 2.3% were either intermediate-susceptible or resistant to the drug. However, imipenem resistance for these isolates did not differ between the two periods and was not more common in patients in an intensive care unit or infections at any specific site. CONCLUSIONS: The frequency of resistance to imipenem is greater among P aeruginosa than among Enterobacter species. Resistance to imipenem among the P aeruginosa isolates is more common from strains isolated from patients with nosocomial infections in an intensive care unit, from the respiratory tract, and from teaching hospitals. Resistance appears to be increasing among nosocomial P aeruginosa isolated in teaching hospitals.     

Antimicrobial use and the influence of inadequate empiric antimicrobial therapy on the outcomes of nosocomial bloodstream infections in a neonatal intensive care unit.

OBJECTIVE: To evaluate antimicrobial use and the influence of inadequate empiric antimicrobial therapy on the outcomes of nosocomial bloodstream infections (BSIs). DESIGN: Prospective cohort study with nested case-control analysis. SETTING: Neonatal intensive care unit (NICU). METHODS: All patients weighing 2,000 g or less were enrolled. Data collection included risk factors for nosocomial BSI, admission severity of illness, microbiology, antimicrobial therapy, and outcomes. Inadequate empiric antimicrobial therapy was defined as the use of antibiotics for more than 48 hours after the day that blood cultures were performed that did not cover the microorganisms causing the bacteremia or administration of antibiotics that failed to cover resistant microorganisms. RESULTS: Two hundred twenty-nine patients were enrolled. Forty-five developed nosocomial BSIs. The BSI rates were 11.2, 2.8, and 0 per 1,000 catheter-days for patients weighing 1,000 g or less, between 1,001 and 1,500 g, and between 1,501 and 2,000 g, respectively. After adjustment for severity of illness, the mortality in patients with nosocomial BSI receiving inadequate empiric antimicrobial therapy was higher than in those receiving adequate therapy (adjusted odds ratio [AOR], 5.3; 95% confidence interval [CI95], 1.2-23.2). By multivariate analysis, nosocomial BSI attributed to Candida species (AOR, 6.3; CI95, 1.4-28.0) and invasive procedure prior to onset of BSI (AOR, 6.4; CI95, 1.0-39.0) were associated with administration of inadequate empiric antimicrobial therapy. CONCLUSIONS: Administration of inadequate empiric antimicrobial therapy among NICU patients with nosocomial BSI was associated with higher mortality. Additional studies on the role of inadequate empiric antimicrobial therapy and the outcomes of BSIs among NICU patients are needed.     

中山市两家医院鲍曼不动杆菌耐药性及同源性分析

目的 了解中山市两家医院临床分离的鲍曼不动杆菌的耐药性及耐碳青霉烯类鲍曼不动杆菌(carbapenem-resistant Acinetobacter baumannii, CRAB)耐药基因的携带情况,并分析其同源性,为医院感染控制提供实验室依据。方法 收集2018年3—8月中山市两家医院临床分离的35株鲍曼不动杆菌,采用最小抑菌浓度(minimum inhibitory concentration, MIC)法进行16种抗菌药物敏感试验,并筛选出CRAB菌株,采用聚合酶链反应(polymerase chain reaction, PCR)扩增CRAB中的耐药基因并测序确认;应用脉冲场凝胶电泳(pulsed-field gel electrophoresis, PFGE)技术对35株鲍曼不动杆菌进行分子分型。结果 35株鲍曼不动杆菌中有33株为CRAB,其余2株对16种抗菌药物全敏感。33株CRAB对替加环素和多粘菌素B均敏感,对米诺环素的敏感率为45.45%,而对其他抗菌药物的耐药率均高达80%以上。33株CRAB均携带OXA-51基因,未检测到IMP和VIM基因。35株鲍曼不动杆菌共分为18个PFGE带型;分为A-F 6个聚类型别,A型(9/35,25.7%)和B型(22/35,62.9%)为主要流行克隆株。结论 鲍曼不动杆菌耐药现象严重,携带多种耐药基因可能是鲍曼不动杆菌对碳青霉烯类等多种抗菌药物耐药的重要原因。医院内存在不同克隆株播散以及同一克隆株在医院间流行播散。     

我国抗菌药物临床应用专项整治情况调查与分析

目的 了解抗菌药物临床应用专项整治以来,我国医院的抗菌药物使用情况。方法 2011年和2012年分别选取了241所医院进行调查。运用系统随机抽样方法抽取5—9月期间医院的门诊处方和住院病历进行分析。抗菌药物使用强度（每百人天DDDs值）、门诊患者抗菌药物处方比例、综合I类切口手术预防使用抗菌药物比例等为主要分析指标。结果 从2011年至2012年,被调查医院的平均抗菌药物使用强度和综合I类切口手术预防使用抗菌药物比例下降有统计学意义;门诊患者抗菌药物处方使用率整体变化不显著,联合用药情况仍普遍存在。且医院的规模与抗菌药物使用存在显著关联性。结论 仍需通过进一步加强抗生素耐药性监测以及对医务工作者和公众抗菌药物使用培训等管理措施,从本质上改善抗菌药物使用情况。     

耐氨基苷类高水平肠球菌医院感染的危险因素及氨基糖苷类耐药相关基因研究

目的 了解耐氨基糖苷类高水平肠球菌(HLAR)的耐药性和医院感染的危险因素,研究HLAR氨基糖苷类耐药相关基因类型分布.方法 采用全自动微生物鉴定仪VITEK-AMS对857株肠球菌属进行鉴定及抗菌药物敏感性检测;PCR法检测HLAR氨基糖苷类耐药相关基因,并对PCR结果进行测序分析.结果 肠球菌属中HLAR占50.4％,利奈唑胺、万古霉素和替考拉宁对HLAR的抗菌作用最好,但有3株屎肠球菌对万古霉素和替考拉宁耐药,粪肠球菌对氯霉素和四环素的耐药率高于屎肠球菌,而屎肠球菌对其他常用抗菌药物的耐药率明显高于粪肠球菌,粪肠球菌和屎肠球菌的耐药谱明显不同,aac(6')-Ie-aph(2〃)-Ia基因为耐庆大霉素高水平肠球菌(HLGR)的主要耐药基因,占HLGR的88.0％,严重的基础疾病、侵入性操作和头孢三代抗菌药物和激素的应用是肠球菌属医院感染的常见危险因素.结论 HLAR已成为医院感染的重要耐药菌,HLGR产生的主要机制是aac(6')-Ie-aph(2〃)-Ia基因介导对庆大霉素高水平耐药,控制常见医院感染危险因素,合理使用抗菌药物,可减少HLAR医院感染的发生.     

Antibiotic resistance in long-term acute care hospitals: the perfect storm.

OBJECTIVE: To examine bacterial antibiotic resistance and antibiotic use patterns in long-term acute care hospitals (LTACHs) and to evaluate effects of antibiotic use and other hospital-level variables on the prevalence of antibiotic resistance. DESIGN: Multihospital ecologic study. METHODS: Antibiograms, antibiotic purchasing data, and demographic variables from 2002 and 2003 were obtained from 45 LTACHs. Multivariable regression models were constructed, controlling for other hospital-level variables, to evaluate the effects of antibiotic use on resistance for selected pathogens. Results of active surveillance in 2003 at one LTACH were available. RESULTS: Among LTACHs, median prevalences of resistance for several antimicrobial-organism pairs were greater than the 90th percentile value for National Nosocomial Infections Surveillance system (NNIS) medical intensive care units (ICUs). The median prevalence of methicillin resistance among Staphylococcus aureus isolates was 84%. More than 60% of patients in one LTACH were infected or colonized with methicillin-resistant S. aureus and/or vancomycin-resistant Enterococcus at the time of admission. Antibiotic consumption in LTACHs was comparable to consumption in NNIS medical ICUs. In multivariable logistic regression modeling, the only significant association between antibiotic use and the prevalence of antibiotic resistance was for carbapenems and imipenem resistance among Pseudomonas aeruginosa isolates (odds ratio, 11.88 [95% confidence interval, 1.42-99.13]; P=.02). CONCLUSIONS: The prevalence of antibiotic resistance among bacteria recovered from patients in LTACHs is extremely high. Although antibiotic use in LTACHs likely contributes to resistance prevalence for some antimicrobial-organism pairs, for the majority of such pairs, other variables, such as prior colonization with and horizontal transmission of antimicrobial-resistant pathogens, may be more important determinants. Further research on antibiotic resistance in LTACHs is needed, particularly with respect to determining optimal infection control practices in this environment.