Limiting the emergence of extended-spectrum Beta-lactamase-producing enterobacteriaceae: influence of patient population characteristics on the response to antimicrobial formulary interventions

Risk factors for fecal carriage of extended-spectrum beta-lactamase-producing and carbapenem-resistant Escherichia coli and Klebsiella pneumoniae strains among patients at hospital admission

AIM

Extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant (CR) Enterobacteriaceae are substantial problems in hospital-acquired infections worldwide. We analyzed the risk factors for fecal carriage of ESBL-positive and/or CR E. coli and K. pneumoniae (EcKp) strains in a hospital in Turkey, an endemic country for both resistances.

MATERIALS AND METHODS

A prospective cross-sectional study including the rectal swab samples of 168 patients, obtained at the day of admission, was conducted. ESBL-producing and CR EcKp were investigated with phenotypic tests and PCR, and the clonal relatedness of isolates was studied. Risk analysis was performed with logistic regression method.

RESULTS

A total of 67 (39.8%) and 21 (12.5%) patient samples tested positive for ESBL-producing and CR EcKp, respectively. CTX-M (n = 27) and OXA-48 (n = 12) were the dominant ESBL and carbapenemase types, and 4.5%-10.7% of the isolates were clonally-related. Among 15 potential risk factors studied, longer lengths of hospital stay and antimicrobial use, and receiving total parenteral nutrition in the last 6 months were determined as independent risk factors for fecal carriage of ESBL-producing and/or CR EcKp, while prior antimicrobial treatment was only a risk factor for ESBL producers.

CONCLUSION

Certain conditions in patients' medical backgrounds may be associated with increased likelihood of resistant bacterial colonization. Notably, questioning these situations at admission can help to identify potential carriers and proactively administer appropriate infection control measures.

Role of antimicrobial restrictions in bacterial resistance control: a systematic literature review

BACKGROUND

Antimicrobial stewardship is considered as one of the most fundamental aspects of bacterial resistance control. Among the multitude of initiatives, restrictive strategies have been widely practiced in hospital settings. However, data concerning their potential effectiveness have not been methodically collected and evaluated to date.

AIM

To identify, collect and evaluate the available evidence regarding the impact of restrictive policies on bacterial resistance in hospital settings.

METHODS

A systematic literature review was conducted using the PubMed/Medline, Embase, Global Health and CINAHL Plus databases.

FINDINGS

In total, 5555 papers were retrieved in the search process, and 29 studies were included in the final analysis. There were no randomized studies, and the inherent limitations of the observational designs employed impede the deduction of safe conclusions. Seemingly beneficial interventions encompass the restriction of broad-spectrum cephalosporins in favour of beta-lactam/lactamase inhibitor combinations as well as the restriction of fluoroquinolones. Antimicrobial restrictions might also play a role in the control of vancomycin-resistant enterococci, while carbapenem stewardship in the form of the preferred use of ertapenem did not produce the anticipated results. Complex restrictions are not offered for informative comparative analyses. Hospital-wide policies could perhaps be superior to those confined to high-risk departments. Carbapenem-resistant Acinetobacter baumannii might be difficult to control through solely formulary interventions.

CONCLUSION

The presumably effective restrictive strategies rely mainly on inadequately tested hypotheses and low-quality evidence. Therefore, systematic, high-quality research is needed to confirm and expand comprehension of the subject so that the most successful policies are employed in the field.

Incidence of Extended-Spectrum β-Lactamase (ESBL)-Producing Escherichia coli and Klebsiella Infections in the United States: A Systematic Literature Review

BACKGROUND

Despite a reported worldwide increase, the incidence of extended-spectrum β-lactamase (ESBL) Escherichia coli and Klebsiella infections in the United States is unknown. Understanding the incidence and trends of ESBL infections will aid in directing research and prevention efforts.

OBJECTIVE

To perform a literature review to identify the incidence of ESBL-producing E. coli and Klebsiella infections in the United States.

DESIGN

Systematic literature review.

METHODS

MEDLINE via Ovid, CINAHL, Cochrane library, NHS Economic Evaluation Database, Web of Science, and Scopus were searched for multicenter (≥2 sites), US studies published between 2000 and 2015 that evaluated the incidence of ESBL-E. coli or ESBL-Klebsiella infections. We excluded studies that examined resistance rates alone or did not have a denominator that included uninfected patients such as patient days, device days, number of admissions, or number of discharges. Additionally, articles that were not written in English, contained duplicated data, or pertained to ESBL organisms from food, animals, or the environment were excluded.

RESULTS

Among 51,419 studies examined, 9 were included for review. Incidence rates differed by patient population, time, and ESBL definition and ranged from 0 infections per 100,000 patient days to 16.64 infections per 10,000 discharges and incidence rates increased over time from 1997 to 2011. Rates were slightly higher for ESBL-Klebsiella infections than for ESBL-E. coli infections.

CONCLUSION

The incidence of ESBL-E. coli and ESBL-Klebsiella infections in the United States has increased, with slightly higher rates of ESBL-Klebsiella infections. Appropriate estimates of ESBL infections when coupled with other mechanisms of resistance will allow for the appropriate targeting of resources toward research, drug discovery, antimicrobial stewardship, and infection prevention.

Infect Control Hosp Epidemiol 2017;38:1209–1215

Impact of an antimicrobial stewardship programme to optimize antimicrobial use for outpatients at an emergency department

BACKGROUND

Antimicrobial stewardship programmes (ASPs) have been effective in optimizing antibiotic use for inpatients. However, an emergency department's fast-paced clinical setting can be challenging for a successful ASP.

AIM

In April 2015, an ASP was implemented in our emergency department and we aimed to determine its impact on antimicrobial use for outpatients.

METHODS

This was a single-centre study comparing the quality of antibiotic prescriptions between a one-year period before ASP implementation (November 2012 to October 2013) and a one-year period after its implementation (June 2015 to May 2016). For each period, antimicrobial prescriptions for all adult outpatients (hospitalized for <24h) were evaluated by an infectious disease specialist and an emergency department physician to assess compliance with local prescribing guidelines. Inappropriate prescriptions were then classified.

FINDINGS

Before and after ASP, 34,671 and 35,925 consultations were registered at our emergency department, of which 25,470 and 26,208 were outpatients. Antimicrobials were prescribed in 769 (3.0%) and 580 (2.2%) consultations, respectively (P < 0.0001). There were 484 (62.9%) and 271 (46.7%) (P < 0.0001) instances of non-compliance with guidelines before and after ASP implementation. Non-compliance included unnecessary antimicrobial prescriptions, 197 (25.6%) vs 101 (17.4%) (P<0.0005); inappropriate spectrum, 108 (14.0%) vs 54 (9.3%) (P=0.008); excessive treatment duration, 87 (11.3%) vs 53 (9.1%) (P>0.05); and inappropriate choices, 11 (1.4%) vs 15 (2.6%) (P>0.05).

CONCLUSION

The implementation of an ASP markedly decreased the number of unnecessary antimicrobial prescriptions, but had little impact on most other aspects of inappropriate prescribing.

Impact of a multifaceted antimicrobial stewardship program: A front-line ownership driven quality improvement project in a large urban emergency department

BACKGROUND

Antibiotic overuse has promoted growing rates of antimicrobial resistance and secondary antibiotic-associated infections such as Clostridium difficile (C. difficile). Antimicrobial stewardship programs (ASPs) are effective in reducing antimicrobial use in the inpatient setting; however, the unique environment of the emergency department (ED) lends itself to challenges for successful implementation. Front-line ownership (FLO) methodology has been shown to be a potentially effective strategy for the implementation of inpatient ASPs through an iterative multi-pronged approach driven by front-line providers.

OBJECTIVE

To determine whether a FLO approach to antimicrobial stewardship in the ED can alter antimicrobial usage.

METHODS

Interventions were driven by ED physicians and facilitated by Infectious Diseases Division physicians from the hospital's ASP using FLO principles. Measured end points included antibiotic usage in the ED as measured by defined daily doses, and rates of urine culture sent from the ED.

RESULTS

There was a step-wise significant reduction in the use of azithromycin (p=0.006), ceftriaxone (p=0.045), ciprofloxacin (p=0.034), and moxifloxacin (p=0.008). There was also a significant reduction in rates of urine cultures (p<0.001) by 2.26 urine cultures per 100 ED patient visits.

CONCLUSIONS

FLO offers a promising approach to successful implementation of an ASP in the ED. Future studies would be important to evaluate the generalizability of the FLO approach to ASP development in other EDs and to determine strategies to improve the sustainability of reductions in antimicrobial use.

Strategies to enhance rational use of antibiotics in hospital: a guideline by the German Society for Infectious Diseases

Introduction

In the time of increasing resistance and paucity of new drug development there is a growing need for strategies to enhance rational use of antibiotics in German and Austrian hospitals. An evidence-based guideline on recommendations for implementation of antibiotic stewardship (ABS) programmes was developed by the German Society for Infectious Diseases in association with the following societies, associations and institutions: German Society of Hospital Pharmacists, German Society for Hygiene and Microbiology, Paul Ehrlich Society for Chemotherapy, The Austrian Association of Hospital Pharmacists, Austrian Society for Infectious Diseases and Tropical Medicine, Austrian Society for Antimicrobial Chemotherapy, Robert Koch Institute.

Materials and methods

A structured literature research was performed in the databases EMBASE, BIOSIS, MEDLINE and The Cochrane Library from January 2006 to November 2010 with an update to April 2012 (MEDLINE and The Cochrane Library). The grading of recommendations in relation to their evidence is according to the AWMF Guidance Manual and Rules for Guideline Development.

Conclusion

The guideline provides the grounds for rational use of antibiotics in hospital to counteract antimicrobial resistance and to improve the quality of care of patients with infections by maximising clinical outcomes while minimising toxicity. Requirements for a successful implementation of ABS programmes as well as core and supplemental ABS strategies are outlined. The German version of the guideline was published by the German Association of the Scientific Medical Societies (AWMF) in December 2013.

The emergence and evolution of antimicrobial resistance: Impact on a global scale

The evolution of antimicrobial resistance is a multifaceted issue that is influenced by numerous factors. This growing healthcare problem has significantly impacted the public welfare and has substantially burdened the economic system on a global scale. In an effort to combat this rising problem, several strategies have been implemented in the recent years to stall the progression and decrease the emergence of antimicrobial resistance. The aim of this review article is to describe the various factors that have contributed to the current state of antimicrobial resistance and to evaluate potential strategies developed to reduce the burden of antimicrobial resistance.

[Management of multiresistant pathogens in urology]

Epidemiological data from recent years confirm the increasing problem of antimicrobial resistance not only for healthcare-associated, gram-positive pathogens but also for gram-negative bacteria. In particular, the progressive increase in resistance to third generation cephalosporins and carbapenems in Enterobacteriaceae is of great concern. With its contribution to infectious morbidity, mortality and financial costs to healthcare systems worldwide, multidrug-resistant pathogens emerge more and more as a public health issue of substantial socioeconomic importance. The Commission for Hospital Hygiene and Infection Prevention (KRINKO) at the Robert Koch Institute (RKI) decided to formulate novel definitions for multidrug-resistance in order to develop hygiene measures for infections and colonization with multidrug-resistant gram-negative bacilli.

Hospital antimicrobial stewardship in the nonuniversity setting

Inappropriate antimicrobial use and antimicrobial resistance persist across the healthcare continuum. Antimicrobial stewardship guidelines assist healthcare institutions in establishing antimicrobial stewardship programs but rely on infectious diseases expertise and leadership, which are not available in all settings. Despite this, many institutions have found ways to use available resources to perform stewardship activities, with improvements in antimicrobial use and reductions in resistance and cost. This article highlights success stories in nonuniversity hospital settings and proposes antimicrobial stewardship strategies that may be more feasible in settings with limited infectious diseases expertise, information technology, or financial resources.

Antimicrobial Stewardship—the State of the Art in 2011 Focus on Outcome and Methods

Antimicrobial stewardship programs attempt to optimize prescribing of these drugs to benefit both current and future patients. Recent regulatory and other incentives have led to widespread adoption of such programs. Measurements of the success of these programs have focused primarily on process measures. However, evaluation of outcome measures will be needed to ensure sustainability of these efforts. Outcome efforts to date provide some evidence for improved care of individual patients, some evidence for minimizing emergence of resistance, and ample evidence for cost reduction. Attention to evaluation methods must be increased to provide convincing evidence for the continuation of such programs.

Antimicrobial stewardship-qualitative and quantitative outcomes: the role of measurement

Overuse and misuse of antibiotics have contributed to the growing problem of antimicrobial resistance and serious side effects including Clostridium difficile infection. The Centers for Disease Control and Prevention estimates that more than 2 million people are infected by multidrug-resistant organisms every year. They propose that promoting antimicrobial stewardship programs (ASP) is an essential component to combat this growing threat. One of the major barriers in implementing effective ASP is the availability of reliable measures which reflect intervention effectiveness. Measuring ASP can be divided into four categories: antimicrobial consumption, process measures, outcome measures, and financial. This article reviews the strengths and weaknesses of the current measures.

Association between adherence to an antimicrobial stewardship program and mortality among hospitalised cancer patients with febrile neutropaenia: a prospective cohort study

BACKGROUND

Initial management of chemotherapy-induced febrile neutropaenia (FN) comprises empirical therapy with a broad-spectrum antimicrobial. Currently, there is sufficient evidence to indicate which antibiotic regimen should be administered initially. However, no randomized trial has evaluated whether adherence to an antimicrobial stewardship program (ASP) results in lower rates of mortality in this setting. The present study sought to assess the association between adherence to an ASP and mortality among hospitalised cancer patients with FN.

METHODS

We conducted a prospective cohort study in a single tertiary hospital from October 2009 to August 2011. All adult patients who were admitted to the haematology ward with cancer and FN were followed up for 28 days. ASP adherence to the initial antimicrobial prescription was determined. The mortality rates of patients who were treated with antibiotics according to the ASP protocol were compared with those of patients treated with other antibiotic regimens. The multivariate Cox proportional hazards model and propensity score were used to estimate 28-day mortality risk.

RESULTS

A total of 307 FN episodes in 169 subjects were evaluated. The rate of adherence to the ASP was 53%. In a Cox regression analysis, adjusted for propensity scores and other potential confounding factors, ASP adherence was independently associated with lower mortality (hazard ratio, 0.36; 95% confidence interval, 0.14-0.92).

CONCLUSIONS

Antimicrobial selection is important for the initial management of patients with FN, and adherence to the ASP, which calls for the rational use of antibiotics, was associated with lower mortality rates in this setting.

Epidemiological interpretation of studies examining the effect of antibiotic usage on resistance

Bacterial resistance to antibiotics is a growing clinical problem and public health threat. Antibiotic use is a known risk factor for the emergence of antibiotic resistance, but demonstrating the causal link between antibiotic use and resistance is challenging. This review describes different study designs for assessing the association between antibiotic use and resistance and discusses strengths and limitations of each. Approaches to measuring antibiotic use and antibiotic resistance are presented. Important methodological issues such as confounding, establishing temporality, and control group selection are examined.

Time series analysis as a tool to predict the impact of antimicrobial restriction in antibiotic stewardship programs using the example of multidrug-resistant Pseudomonas aeruginosa

The association between antimicrobial consumption and resistance in nonfermentative Gram-negative bacteria is well-known. Antimicrobial restriction, implemented in clinical routines by antibiotic stewardship programs (ASPs), is considered a means to reduce resistance rates. Whether and how antimicrobial restriction can accomplish this goal is still unknown though. This leads to an element of uncertainty when designing strategies for ASPs. From January 2002 until December 2011, an observational study was performed at the University Hospital Tübingen, Tübingen, Germany, to investigate the association between antimicrobial use and resistance rates in Pseudomonas aeruginosa. Transfer function models were used to determine such associations and to simulate antimicrobial restriction strategies. Various positive associations between antimicrobial consumption and resistance were observed in our setting. Surprisingly, impact estimations of different antimicrobial restriction strategies revealed relatively low intervention expenses to effectively attenuate the observed increase in resistance. For example, a simulated intervention of an annual 4% reduction in the use of meropenem over 3 years from 2009 until 2011 yielded a 62.5% attenuation (95% confidence interval, 15% to 110%) in the rising trend of multidrug-resistant Pseudomonas aeruginosa (three- and four-class-resistant P. aeruginosa [34MRGN-PA]). Time series analysis models derived from past data may be a tool to predict the outcome of antimicrobial restriction strategies, and could be used to design ASPs.

Antimicrobial agent exposure and the emergence and spread of resistant microorganisms: issues associated with study design

Antibiotics are essential agents that have greatly reduced human mortality due to infectious diseases. Their use, and sometimes overuse, have increased over the past several decades in humans, veterinary medicine and agriculture. However, the emergence of resistant pathogens is becoming an increasing problem that could result in the re-emergence of infectious diseases. Antibiotic prescription in human medicine plays a key role in this phenomenon. Under selection pressure, resistance can emerge in the commensal flora of treated individuals and disseminate to others. However, even if the effects of antimicrobial use on resistance is intuitively accepted, scientific rationales are required to convince physicians, legislators and public opinion to adopt appropriate behaviours and policies. With this review, we aim to provide an overview of different epidemiological study designs that are used to study the relationship between antibiotic use and the emergence and spread of resistance, as well as highlight their main strengths and weaknesses.

Clinical impact and risk factors for colonization with extended-spectrum β-lactamase-producing bacteria in the intensive care unit

PURPOSE

The changed epidemiology of extended spectrum beta-lactamases (ESBL), the spread to the community and the need for prudent use of carbapenems require updated knowledge of risk factors for colonization with ESBL-producing enterobacteriaceae (ESBL-PE).

METHODS

An 8-month prospective study in the medical ICU of an 850-bed general and university-affiliated hospital.

RESULTS

Of 610 patients admitted, 531 (87 %) had a rectal swab obtained at admission, showing a 15 % (82 patients) ESBL-PE carriage rate, mostly of E. coli (n = 51, 62 %); ESBL-PE caused 9 (3 %) infections on admission. By multivariable analysis, transfer from another ICU (OR = 2.56 [1, 22]), hospital admission in another country [OR = 5.28 (1.56-17.8)], surgery within the past year [OR = 2.28 (1.34-3.86)], prior neurologic disease [OR = 2.09 (1.1-4.0)], and prior administration of third generation cephalosporin (within 3-12 months before ICU admission) [OR = 3.05 (1.21-7.68)] were independent predictive factors of colonization by ESBL-PE upon ICU admission. Twenty-eight patients (13 % of those staying for more than 5 days) acquired ESBL carriage in ICU, mostly with E. cloacae (n = 13, 46 %) and K. pneumoniae (n = 10, 36 %). In carriers, ESBL-PE caused 10 and 27 % of first and second episodes of ICU-acquired infections, respectively.

CONCLUSION

We found a high prevalence of ESBLE-PE colonization on admission to our ICU, even in the subgroup admitted from the community, but few first infections. Identifying risk factors for ESBL-PE colonization may help identifying which patients may warrant empiric ESBL-targeted antimicrobial drug therapy as a means to limit carbapenem use.

Antimicrobial stewardship programs in community hospitals: the evidence base and case studies

By controlling and changing how antimicrobial agents are selected and administered, antimicrobial stewardship programs (ASPs) aim to prevent or slow the emergence of antimicrobial resistance; optimize the selection, dosing, and duration of antimicrobial therapy; reduce the incidence of drug-related adverse events; and lower rates of morbidity and mortality, length of hospitalization, and costs. There is an abundant and growing body of evidence demonstrating that ASPs change the quantity and quality of antimicrobial prescriptions; however, measuring whether, when, and how ASPs improve patient outcomes and change patterns of antimicrobial resistance--which is the ultimate goals of ASPs--has been difficult, but the totality of evidence indicates that ASPs are capable of achieving these goals. In this article, we review the existing data on ASPs and their effects on patient care and antimicrobial resistance, as well as strategies for establishing ASPs in different types of hospitals.

Antimicrobial stewardship: attempting to preserve a strategic resource

Antimicrobials hold a unique place in our drug armamentarium. Unfortunately the increase in resistance among both gram-positive and gram-negative pathogens coupled with a lack of new antimicrobial agents is threatening our ability to treat infections. Antimicrobial use is the driving force behind this rise in resistance and much of this use is suboptimal. Antimicrobial stewardship programs (ASP) have been advocated as a strategy to improve antimicrobial use. The goals of ASP are to improve patient outcomes while minimizing toxicity and selection for resistant strains by assisting in the selection of the correct agent, right dose, and best duration. Two major strategies for ASP exist: restriction/pre-authorization that controls use at the time of ordering and audit and feedback that reviews ordered antimicrobials and makes suggestions for improvement. Both strategies have some limitations, but have been effective at achieving stewardship goals. Other supplemental strategies such as education, clinical prediction rules, biomarkers, clinical decision support software, and institutional guidelines have been effective at improving antimicrobial use. The most effective antimicrobial stewardship programs have employed multiple strategies to impact antimicrobial use. Using these strategies stewardship programs have been able to decrease antimicrobial use, the spread of resistant pathogens, the incidence of C. difficile infection, pharmacy costs, and improved patient outcomes.

Epidemiology of an outbreak of antibiotic-resistant Klebsiella pneumoniae at a tertiary care medical center

BACKGROUND

In 2004, a 650-bed, tertiary care medical center experienced an outbreak of multiple antibiotic-resistant Klebsiella pneumoniae (MR-KP) that included extended-spectrum beta-lactamase (ESBL)-producing and non-ESBL-producing strains.

METHODS

Characteristics associated with MR-KP were evaluated by case-control study with variables tested by conditional regression analyses. Pulsed-field gel electrophoresis (PFGE) was used to compare the molecular relatedness of isolates.

RESULTS

In 2004, the incidence rate of MR-KP increased significantly compared with 2003 (relative risk [RR], 5.1; 95% confidence interval [CI]: 3.10-8.37) when only ESBL-producing K pneumoniae were present. The increase involved both ESBL-producing MR-KP and MR-KP in which ESBL production was not detected by the testing in use. Nineteen isolates were identical or closely related by PFGE. Characteristics associated with MR-KP were longer length of hospital stay (odds ratio [OR], 2.92; 95% CI: 1.17-7.30; P = .022), greater total antibiotic-days (OR, 2.81; 95% CI: 1.19-6.65; P = .018], and higher Acute Physiology and Chronic Health Evaluation (APACHE) II score (OR, 1.15; 95% CI: 1.06-1.25; P = .001). When the MR-KP cases were subdivided into ESBL-producing K pneumoniae and ESBL-negative K pneumoniae, while controlling for length of stay, total antibiotic-days was significantly associated with ESBL-producing K pneumoniae (OR, 3.8; 95% CI: 1.2-12.1; P = .02).

CONCLUSION

Compared with patients housed on the same unit at the same time, patients with MR-KP had a longer length of stay and greater antibiotic exposure. Patients with longer length of stay and greater total antibiotic exposure should be potential targets for stringent infection control measures.

Antimicrobial stewardship: application in the intensive care unit

Critical-care units can be barometers for appropriate antimicrobial use. There, life and death hang on empirical antimicrobial therapy for treatment of infectious diseases. With increasing therapeutic empiricism, triple-drug, broad-spectrum regimens are often necessary, but cannot be continued without fear of the double-edged sword: a life-saving intervention or loss of life following Clostridium difficile infection, infection from a resistant organism, nephrotoxicity, cardiac toxicity, and so on. While broadened initial empirical therapy is considered a standard, it must be necessary, dosed according to pharmacokinetic-pharmacodynamic principles, and stopped when no longer needed. Antimicrobial stewardship interventions shepherd these considerations in antimicrobial therapy. With pharmacists and physicians trained in infectious disease and critical care, clear-cut interventions can be focused on beginning or growing a stewardship program, or proposing future studies.

Epidemiology of antimicrobial resistance among gram-negative organisms recovered from patients in a multistate network of long-term care facilities

We identified 1,805 gram-negative organisms in cultures of urine samples obtained over a 10-month period from residents of 63 long-term care facilities. The prevalence of fluoroquinolone resistance in Escherichia coli was 51% (446 of 874 isolates), whereas the prevalences of ceftazidime and imipenem resistance in Klebsiella species were 26% and 6% (84 and 19 of 323 isolates), respectively. The prevalence of resistance varied significantly by facility type, size, and geographic location.

Antimicrobial use: risk driver of multidrug resistant microorganisms in healthcare settings

PURPOSE OF REVIEW

This review explores recent evidence on the association between antibiotics usage and resistance.

RECENT FINDINGS

A meta-analysis showed that the risk of acquiring methicillin-resistant Staphylococcus aureus was increased by 1.8-fold in patients who had taken antibiotics. Such risk was almost three-times greater after using quinolones or glycopeptides. Significant heterogeneity between studies was mainly related to study designs. A Cochrane systematic review suggested that, although the quality of the evidence was poor, interventions to improve hospital antibiotic prescribing were associated with a reduction in the incidence of antimicrobial resistant pathogens. Against this evidence, mupirocin-resistant S. aureus and linezolid-resistant vancomycin-resistant enterococci (VRE) were detected in institutions where these drugs were not widely used. Studies assessing the impact of vancomycin prescribing restriction on VRE rates were heterogeneous and the effectiveness of such interventions remains poorly defined. Important confounders of studies, other than study design, are the lack of analysis of secular trends of infections, colonization pressure in the ward and duration of follow up.

SUMMARY

Available evidence, although not always of high quality, suggests that a link between antibiotics usage at individual and institutional levels and resistant bacteria does exist. Benchmark guidelines for empiric therapy in hospitalized patients, taking into consideration not only patients' needs but also ecological costs of resistance, should be rapidly developed.

Impact of a hospital-wide antimicrobial formulary intervention on the incidence of multidrug-resistant gram-negative bacteria

We examined the impact of an antimicrobial formulary change, based on reduction in third-generation cephalosporin use, on resistant gram-negative pathogens in a tertiary hospital. No significant changes were demonstrated in their incidence per 1000 patient-days. Otherwise, there was a significant decrease in rate of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae (63.1% to 52.5%, P = .04) and third-generation cephalosporin-resistant Enterobacter species (31.4% to 25%, P = .04) between the 2 study periods. On the other hand, there was also a significant increase in rate of ampicillin-sulbactam-resistant Acinetobacter baumannii (8% to 47%, P = .01) after the implementation of the formulary intervention.

Antimicrobial drug use and antibiotic-resistant bacteria

Antimicrobial Drug Use and Antibiotic-Resistant Bacteria (response)

Risk factors for colonization with extended-spectrum beta-lactamase-producing bacteria and intensive care unit admission

Coexisting conditions and previous antimicrobial drug exposure predict colonization.

Extended-spectrum β-lactamase (ESBL)–producing bacteria are emerging pathogens. To analyze risk factors for colonization with ESBL-producing bacteria at intensive care unit (ICU) admission, we conducted a prospective study of a 3.5-year cohort of patients admitted to medical and surgical ICUs at the University of Maryland Medical Center. Over the study period, admission cultures were obtained from 5,209 patients. Of these, 117 were colonized with ESBL-producing Escherichia coli and Klebsiella spp., and 29 (25%) had a subsequent ESBL-positive clinical culture. Multivariable analysis showed the following to be statistically associated with ESBL colonization at admission: piperacillin-tazobactam (odds ratio [OR] 2.05, 95% confidence interval [CI] 1.36–3.10), vancomycin (OR 2.11, 95% CI 1.34–3.31), age >60 years (OR 1.79, 95% CI 1.24–2.60), and chronic disease score (OR 1.15; 95% CI 1.04–1.27). Coexisting conditions and previous antimicrobial drug exposure are thus predictive of colonization, and a large percentage of these patients have subsequent positive clinical cultures for ESBL-producing bacteria.

Patient-to-patient transmission is important in extended-spectrum beta-lactamase-producing Klebsiella pneumoniae acquisition

We performed a prospective cohort study to quantify the number of cases of patient-to-patient transmission of extended-spectrum beta-lactamase-producing Klebsiella species on perianal surveillance culture. Among 27 patients who acquired Klebsiella pneumoniae infection, 14 had infections (52%) that were due to patient-to-patient transmission, and 6 (22%) had a subsequent positive extended-spectrum beta-lactamase clinical culture results.