Society for Healthcare Epidemiology of America and Infectious Diseases Society of America Joint Committee on the Prevention of Antimicrobial Resistance: guidelines for the prevention of antimicrobial resistance in hospitals

A pilot study of antibiotic cycling in the community hospital setting

OBJECTIVE

To assess the feasibility of a quarterly antibiotic cycling program at two community hospitals and to evaluate its safety and impact on antibiotic use, expenditures, and resistance.

DESIGN

Nonrandomized, longitudinal cohort study.

SETTING

Two community hospitals, one teaching and one non-teaching.

PATIENTS

Adult medical and surgical inpatients requiring empiric antibiotic therapy.

INTERVENTION

We developed and implemented a treatment protocol for the empiric therapy of common infections. Between July 2000 and June 2002, antibiotics were cycled quarterly; quinolones, beta-lactam-inhibitor combinations, and cephalosporins were used. Protocol adherence, adverse drug events, nosocomial infections, antibiotic use and expenditures, resistance among clinical isolates, and length of stay were assessed during eight quarters.

RESULTS

Physicians adhered to the protocol for more than 96% of 2,494 eligible patients. No increases in nosocomial infections or adverse drug events were attributed to the cycling protocol. Antibiotic acquisition costs increased 31%; there was a 14.7% increase in antibiotic use. Length of stay declined by 1 day. Quarterly variability in the prevalence of vancomycin-resistant enterococci and ceftazidime resistance among combined gram-negative organisms were noted.

CONCLUSIONS

Implementation of an antibiotic cycling program is feasible in a community hospital setting. No adverse safety concerns were identified. Antibiotic cycling was more expensive, partly due to an increase in antibiotic use to optimize initial empiric therapy. Quarterly antibiogram patterns suggested that antibiotic cycling may have impacted resistance, although the small number of isolates precluded statistical analysis. Further assessment of this approach is necessary to determine its relationship to antimicrobial resistance.

Investigation of a nosocomial outbreak of extended-spectrum beta-lactamase VEB-1-producing isolates of Acinetobacter baumannii in a hospital setting

A nosocomial outbreak of epidemiologically related VEB-1 extended-spectrum beta-lactamase-producing isolates of Acinetobacter baumannii occurred in 33 patients in an intensive care unit. A case-control study identified previous treatment with third-generation cephalosporins as the only risk factor for A. baumannii acquisition. Rationale for antibiotic use should be strengthened.

Estimation of methicillin-resistant Staphylococcus aureus transmission by considering colonization pressure at the time of hospital admission

Our objective was to evaluate the accuracy of a methicillin-resistant Staphylococcus aureus (MRSA) rate using the imported MRSA reservoir identified at the time of hospital admission. Two indicators were used: the number of imported MRSA patient-days/total number of patient-days [representing colonization pressure (CP) at the time of admission] and the incidence of hospital-acquired MRSA isolated from clinical samples expressed as density/100 patient-days for carriers identified at the time of admission [representing the incidence taking CP into account (ICP)]. The variations of these indicators were analysed and compared with two more common indicators: percentage of MRSA acquired in our hospital and the incidence of hospital-acquired MRSA isolated from clinical samples expressed as density/1000 patient-days within three four-month periods during 2002. Common indicators varied similarly, with marked decline during the third period; first-period CP was twice that of other periods (P<10(-6)) and the highest (>two-fold) ICP was seen in the summer (second) period (P<0.001) when the personnel/patient ratio was the lowest. Thus, comparison of different indicators within four-month periods underlines important differences between common and novel indicators. Despite several limitations, ICP should be helpful in the interpretation of MRSA surveillance data, particularly for estimating the extent of MRSA transmission.

Impact of restricting fluoroquinolone prescription on bacterial resistance in an intensive care unit

The purpose of this study was to assess the effect of reducing prescription of fluoroquinolones in an intensive care unit (ICU) upon bacterial resistance, particularly as regards Pseudomonas aeruginosa. For six months between January 2001 and June 2001, administration of fluoroquinolones was kept to a minimum. A bacteriological screening of patients was performed to assess the incidence of fluoroquinolone-resistant bacteria. There was a 75.8% restriction in prescriptions of fluoroquinolones. There was no significant change in bacterial ecology between the periods preceding (12 months) and following (12 months) restriction. There was a significant recovery of sensitivity of P. aeruginosa to ciprofloxacin (P<or=0.01), with a decrease in resistant strains from 71.3% in the pre-restriction period to 52.4% in the post-restriction period. Regarding clinical data, no significant differences were noted between the pre-restriction and the post-restriction periods, except for the number of cases of ventilator-associated pneumonia with P. aeruginosa resistant to ciprofloxacin. This study demonstrated the possibility of introducing rotation of antibiotics in an ICU.

Preventing antimicrobial-resistant bacterial infections among older adults in long-term care facilities

For older adults in long-term care facilities (LTCFs), the rate of infections caused by antimicrobial resistant strains of bacteria has increased and is prompting renewed interest in investing health care resources for prevention and control of these pathogens. This document offers a simple framework to combat infections due to antimicrobial resistant bacteria in LTCF residents by providing a multi-step approach consisting of four major strategies: prevent infection, diagnose and treat infection effectively, use antimicrobials wisely, and prevent transmission. Recommendations from this multi-step approach are directed at LTCF medical directors and practicing clinicians involved with the medical care of older adult LTCF residents.

A multidisciplinary approach to antimicrobial stewardship: evolution into the 21st century

In the 21st century, we face the problems of escalating antibiotic resistance, difficult-to-treat infections and slowed new drug development. Healthcare practitioners are increasingly recognising the importance of good antimicrobial stewardship. Various strategies such as formulary management, prior approval, clinical pathways, post-prescribing evaluation and intravenous to oral conversion have been used singly or in combination to improve prescribing and reduce costs. Combining a multifaceted approach with a full-time dedicated multidisciplinary team appears to be capable of yielding satisfactory clinical and economic outcomes and most importantly, sustaining efforts of antimicrobial stewardship. The multidisciplinary approach to antibiotic management should be tailored to fit the individual needs of an institution. More data are needed to document effects on curbing resistance.

Impact of implementing a method of feedback and accountability related to contact precautions compliance

BACKGROUND

In January 2002, Infection control professionals for Spartanburg Regional Healthcare System held a planning retreat focused on patient safety. The main challenge discussed was the control of antibiotic-resistant organisms. Rounds on the patient care units had revealed compliance issues with the current isolation procedures. The team developed a process improvement project coined the Effective Processes in Infection Control Project (EPIC). With a broad challenge of antibiotic resistance, the focus was narrowed to isolation precautions for methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

The initial stage of the EPIC project was education, followed by routine unit rounds to monitor compliance. A tool was developed to provide immediate feedback for the nursing units. Summary reports were generated for clinical directors as a method of accountability for unit leadership. Rates for facility-acquired MRSA were monitored and compared with MRSA days at risk.

RESULTS

Over a 1-year period of increased accountability, the facility-acquired rate of MRSA decreased by 30%, even though the days at risk increased. The decrease was maintained during year 2.

CONCLUSIONS

The results of this project point to the importance of accountability with isolation precautions in the effort to combat the spread of MRSA in the hospital setting.

Is bilateral protected specimen brush sampling necessary for the accurate diagnosis of ventilator-associated pneumonia?

BACKGROUND

Clinical acumen alone is unreliable in establishing a diagnosis of ventilator-associated pneumonia (VAP) and controversy exists over which diagnostic tools should be utilized to confirm a clinical suspicion of VAP. The purpose of this study was to determine the reliability of blind protected specimen brush (PSB) sampling in the diagnosis of VAP and if bilateral PSB sampling is necessary.

METHODS

Prospective study comparing blind PSB sampling with bronchoscopic directed PSB sampling in thirty-four consecutive SICU patients with a clinical suspicion of VAP. All patients underwent blind PSB sampling followed by bronchoscopic directed contralateral PSB sampling.

RESULTS

Twenty-four of 34 patients (71%) were diagnosed to have VAP. The concordance rate between blind and directed PSB samples was 53% (18/34). When blind PSB was positive (15/34), the contralateral sample yielded a different microorganism in three patients (9%). When blind PSB was negative (19/34), infection was present in the contralateral lung in nine patients (26%). Blind PSB sampling alone was inaccurate in 35% of patients.

CONCLUSIONS

The low concordance between blind and directed PSB suggests the need to sample both lung fields. Bilateral PSB sampling can identify unsuspected pathogenic microorganisms in the contralateral lung.

Impact of regular attendance by infectious disease specialists on the management of hospitalised adults with community-acquired febrile syndromes

The impact of attendance by infectious disease specialists (IDS) on hospitalised adults with community-acquired infection was assessed by studying 402 consecutive febrile adults who were admitted randomly to either of two internal medicine wards over a 4-month period and given intravenous antibiotics. In ward 1, patients were attended by IDS, whereas those in ward 2 were attended by physicians from other specialties. In total, 160 patients were treated in ward 1 and 242 in ward 2 (median age 66 years; 49% male). The case-mix was comparable. Only 39% of ward 2 patients underwent minimal fever diagnostic tests compared to 82% in ward 1 (p < 0.001). Ward 1 and 2 patients received 188 and 315 antibiotic courses, respectively, of which 32% and 20% required approval from IDS (p 0.003). Patients in ward 1 were more likely to receive ceftriaxone (7.5% vs. 2%; p 0.002), erythromycin (7% vs. 1.5%; p 0.002) and cefuroxime (48% vs. 26%; p < 0.0001), but were less likely to receive amoxycillin-clavulanate (8% vs. 28%; p < 0.0001). The mean durations of therapy were 3.6 and 3.2 days (not significant), and therapy was deemed to be completely appropriate in 55.5% and 43% of cases, respectively (p 0.012). The crude mortality rates were 6.3% and 7.9%, respectively (not significant), while the medication costs were US dollars 27.4 and US dollars 26.4/patient/antibiotic day, respectively. Regular attendance by IDS resulted in significantly higher rates of accurate diagnosis and appropriate therapy. IDS prescribed more restricted (and expensive) agents, but preferred less expensive agents among unrestricted drugs, thereby offsetting the overall medication costs.

Prior antimicrobial therapy in the hospital and other predisposing factors influencing the usage of antibiotics in a pediatric critical care unit

Background

The aim of this study was to determine whether prior antimicrobial therapy is an important risk factor for extended antimicrobial therapy among critically ill children. To evaluate other predisposing factors influencing the usage of antibiotics in a pediatric intensive care unit (PICU) setting. To examine the relationship between the extent of antimicrobial treatment and the incidence of nosocomial infections and outcome.

Methods

This prospective observational cohort study was conducted at a university-affiliated teaching hospital (760 beds) in Athens. Clinical data were collected upon admission and on each consecutive PICU day. The primary reason for PICU admission was recorded using a modified classification for mutually exclusive disease categories. All administered antibiotics to the PICU patients were recorded during a six-month period. Microbiological and pharmacological data were also collected over this period. The cumulative per patient and the maximum per day numbers of administered antibiotics, as well as the duration of administration were related to the following factors: Number of antibiotics which the patients were already receiving the day before admission, age groups, place of origin, the severity of illness, the primary disease and its complications during the course of hospitalization, the development of nosocomial infections with positive cultures, the presence of chronic disease or immunodeficiency, various interventional techniques (mechanical ventilation, central catheters), and PICU outcome.

Results

During a six-month period 174 patients were admitted to the PICU and received antibiotics for a total of 950 days (62.3% of the length of stay days). While in PICU, 34 patients did not receive antimicrobial treatment (19.5%), 69 received one antibiotic (39.7%), 42 two (24.1%), 17 three (9.8%), and 12 more than three (6.9%). The number of antibiotics prescribed in PICU or at discharge did not differ from that at admission. Indications for receiving antibiotics the day before admission and throughout during hospitalization into PICU were significantly correlated. Although the cumulative number of administered antibiotics did not correlate with mortality (9.8%), it was significantly related to the severity scoring systems PRISM (p < .001), TISS (p < .002) and was significantly related to the number of isolated microorganisms (p < .0001). Multiple regression analysis demonstrated that independent determinants of the cumulative number of antibiotics were: prior administration of antibiotics, presence of a bloodstream infection, positive bronchial cultures, immunodeficiency, and severity of illness.

Conclusion

Prior antimicrobial therapy should be recognized as an important risk factor for extended antimicrobial therapy among critically ill children. Severity of illness, immunodeficiency, and prolonged length of stay are additional risk factors.

Information resources used in antimicrobial prescribing

To describe resources clinicians use when they prescribe antimicrobials, the authors surveyed prescribers by telephone within hours (median 2.9) after they ordered one or more antimicrobials for a patient. Among 157 prescribers, 87 (55%) used one or more external resources to aid in decisions about their order. The other 70 (45%) used only their own knowledge and experience. Fifty-nine (38%) consulted another person. Fifty-four (34%) used a print, computer, or Internet resource. In multivariate analysis, use of an external resource was associated with the clinician being on the medical service (odds ratio [OR] 2.99, 95% confidence interval [CI] 1.41-6.3) or being an intern (OR 13.65, 95% CI 1.44-128). Eighty percent of providers said information about antimicrobial prescribing at the point of electronic order entry would be helpful. It was concluded that decision support at the point of electronic order entry is likely to be used and might improve antimicrobial prescribing.

Quelles stratégies découlent de la surveillance des bactéries multirésistantes aux antibiotiques afin de mieux maîtriser leur diffusion ?

Should we screen for colonization to control the spread of multidrug-resistant bacteria? A multidrug-resistant bacteria surveillance program was performed in 1999 at Laënnec Hospital (Nantes, France). After a 3-year period, the results permit us to determine the strategy to strengthen their spread. In 2001, Staphylococcus aureus resistant to methicillin represented 45% of the 202 multidrug-resistant bacteria isolated. The global incidence rate per 100 admissions remained stable between 1999 and 2001 (0.42%), but those of infections acquired in our institution decreased significantly from 0.27% in 1999 to 0.18% in 2001 (P < 0.05), particularly in medical care units (P < 0.04). In spite of this surveillance program and hygiene trainings, the global incidence remained stable during the study period, even if our action contributed to decrease the incidence of S. aureus resistant to methicillin acquired in our institution. Isolation precautions and screening for colonization policy in intensive care units are not sufficient to control the spread of MRB at hospital level. They should be strengthened by procedures for the transfer of infected or colonized patients and by antibiotic use control.

Vancomycin use in hospitalized pediatric patients

OBJECTIVES

To assess vancomycin utilization at children's hospitals, to determine risk factors for vancomycin use and length of therapy, and to facilitate adapting recommendations to optimize vancomycin prescribing practices in pediatric patients.

METHODS

Two surveys were conducted at Pediatric Prevention Network hospitals. The first (Survey I) evaluated vancomycin control programs. The second (Survey II) prospectively reviewed individual patient records. Each hospital was asked to complete questionnaires on 25 consecutive patients or all patients for whom vancomycin was prescribed during a 1-month period.

RESULTS

In Survey I, 55 of 65 (85%) hospitals reported their vancomycin control policies. Three quarters had specific policies in place to restrict vancomycin use. One half had at least 3 vancomycin restriction measures. In Survey II, personnel at 22 hospitals reviewed 416 vancomycin courses, with 2 to 25 (median = 12) patients tracked per hospital. Eighty-two percent of the vancomycin prescribed was for treatment of neonatal sepsis, fever/neutropenia, fever of unknown origin, positive blood culture, pneumonia, or meningitis. In an additional 6% (26/416), vancomycin was prescribed for patients with beta-lactam allergies and in 13% (56/416) for prophylaxis. Median duration of prophylaxis was 2 days (range: 1-15 days). Almost half (196, 47%) of the patients who received vancomycin were in intensive care units; 27% of the vancomycin courses were initiated by neonatologists and 19% by hematologists/oncologists. The predominant risk factor at the time of vancomycin initiation was the presence of vascular catheters (322, 77%); other host factors included cancer chemotherapy (55, 13%), transplant (30, 7%), shock (24, 6%), other immunosuppressant therapy (17, 4%), or hyposplenic state (2, <1%). Other clinical considerations were severity of illness (96, 23%), uncertainty about diagnosis (51, 12%), patient not responding to current antibiotic therapy (40, 10%), or implant infection (13, 3%). When vancomycin was initiated, blood cultures were positive in 85 patients (20%); cultures from other sites were positive in 45 (11%), and Gram stains of body fluids were positive in 37 (9%). In 29 (7%) patients, organisms sensitive only to vancomycin were isolated before vancomycin initiation. Reasons for discontinuing vancomycin included: therapeutic course completed (125, 30%), negative cultures (106, 25%), alternative antibiotics initiated (75, 18%), illness resolved (14, 3%), or patient expired (13, 3%). Final results of blood culture isolates resistant to beta-lactam antibiotics included 48 coagulase-negative staphylococcus, 5 Staphylococcus aureus, and 10 other species.

CONCLUSIONS

At children's hospitals, vancomycin is initiated for therapy in patients who have vascular catheters and compromised host factors. Only 7% had laboratory-confirmed beta-lactam-resistant organisms isolated at the time vancomycin was prescribed. Efforts to modify empiric vancomycin use in children's hospitals should be targeted at intensivists, neonatologists, and hematologists. Initiatives to decrease length of therapy by decreasing the number of surgical prophylaxis doses and days of therapy before laboratory results may decrease vancomycin exposure.

Multidisciplinary antimicrobial management and the role of the infectious diseases pharmacist--a UK perspective

Improved clinical outcome, patient safety, cost savings and a reduction in the burden of antimicrobial resistance are outcomes associated with optimizing antimicrobial use. Despite this, the misuse of antimicrobials in the hospital setting remains a huge problem. The development of antimicrobial management teams and the promotion of the role of the clinical pharmacist in antimicrobial prescribing are recommended strategies for improving prescribing practice. It is recognized that there is a lack of published evidence-based research looking at the effects of antimicrobial control programmes and there is a need for more data. In the UK, the role of the hospital pharmacist in promoting responsible antimicrobial prescribing has been largely undervalued and needs to be encouraged and formalized in line with current directives. Managerial structures within hospitals need to endorse multidisciplinary antimicrobial management schemes with appropriate authoritative, administrative and information technology support.

Current implications of drug resistance in spinal cord injury

A 54-yr-old man with C6 quadriplegia and a neurogenic bowel and bladder was evaluated for clearance of a urinary tract infection after treatment for organisms susceptible to the antibiotics used, and an organism resistant to all antibiotics on the panel grew on the initial follow-up urine culture. Multidrug-resistant organisms present increasing challenges and risks in the management of the neurogenic bladder in patients with spinal cord injury. In an effort to control and reduce the impact and risk associated with these organisms, management methods of the neurogenic bladder and infection control policies should be adjusted according to guidelines from the Centers for Disease Control and related research; such policies could include surveillance for multidrug-resistant organisms and isolation of patients who test positive for these organisms.

[Evaluation of the efficacy of a multiresistant bacteria control programme in a teaching hospital, studying the evolution of methicillin-resistant Staphylococcus aureus incidence]

Methicillin-resistant Staphylococcus aureus (MRSA) constitute the most important multiresistant bacteria (MRB) recovered in French hospitals. Our objective was to measure these MRSA diffusion in our hospital to evaluate the MRB control programme which had been implemented in the beginning of 1999. This study was conducted in a teaching hospital containing 1800 beds, from February 1999 to January 2001. All MRSA isolated in clinical samples were included. Duplicates (same bacteria in the same patient) were excluded. The detection of methicillin-resistance was performed at 30 degrees C, by disk diffusion method. Incidence densities were determined with their 95% confidence interval (CI 95%). Their evolution by four-month period was evaluated with the chi-square test for trend. During the two-year period, 866 MRSA were isolated. The global incidence was 0,88 per 1000 patient-days (PD) (IC 95% = left open bracket 0,83-0,93 right open bracket ). For cases acquired in our hospital the incidence was 0,66 per 1000 PD, whereas it was 0,26 per 1000 PD for imported cases. Concerning the evolution of incidences, no significant trend was observed for global incidence. The incidence of acquired MRSA decreased during the first year, but increased thereafter. The incidence of imported MRSA increased with a significant trend (p < 10(-5)). The number of these imported MRSA isolated in our hospital was twice fold higher in 2000. This study emphasizes an important actual problem : the increase of patient colonization pressure at the time of admission in hospitals. This increase, which can be due in part to a community transmission, is responsible for a reduction of the efficacy of MRSA control programmes.

Risk of resistant infections with Enterobacteriaceae in hospitalized neonates

OBJECTIVE

To determine the risk factors associated with progression from colonization to infection with health care-associated antimicrobial-nonsusceptible Enterobacteriaceae (ANE) in critically ill neonates.

STUDY DESIGN

During a 3-year period (1998 to 2000), surveillance rectal cultures were performed on neonates admitted to our Level III neonatal intensive care unit after a cluster of four cases of ANE infection were identified in 1998. ANE were defined as members of the Enterobacteriaceae family that exhibited nonsusceptibility to ceftazidime or laboratory evidence of extended spectrum beta-lactamase (ESBL) production.

RESULTS

A total of 1,710 patients were admitted to the neonatal intensive care unit during the study period. Of the 1,710 patients 300 (18%) were excluded from the risk factor analysis. Of the 1,410 remaining neonates the incidence of health care-associated ANE colonization was 17% (240 of 1,410 patients), and 14% of the colonized patients (34 of 240 patients) developed ANE infections. Of the 206 ANE-colonized patients who did not develop disease, 60 (29%) harbored ESBL-producing isolates. Of the 34 ANE-infected patients, 14 (41%) yielded growth of ESBL-producing isolates. Multiple logistic regression analysis revealed that colonized neonates with very low birth weights (<1,000 g) and those who had received prolonged exposures to antimicrobial agents were at increased risk of ANE infections.

CONCLUSIONS

Colonization with ANE places hospitalized neonates at risk for development of systemic infections. Very low birth weight (<1,000 g) and prolonged exposure to antimicrobial agents were the only two independent risk factors associated with ANE infection.

Monitoring antimicrobial use and resistance: comparison with a national benchmark on reducing vancomycin use and vancomycin-resistant enterococci

To determine if local monitoring data on vancomycin use directed quality improvement and decreased vancomycin use or vancomycin-resistant enterococci (VRE), we analyzed data from 50 intensive-care units (ICUs) at 20 U.S. hospitals reporting data on antimicrobial-resistant organisms and antimicrobial agent use. We compared local data with national benchmark data (aggregated from all study hospitals). After data were adjusted for changes in prevalence of methicillin-resistant Staphylococcus aureus, changes in specific prescriber practice at ICUs were associated with significant decreases in vancomycin use (mean decrease -48 defined daily doses per 1,000 patient days, p<0.001). These ICUs also reported significant decreases in VRE prevalence compared with those not using unit-specific changes in practice (mean decrease of 7.5% compared with mean increase of 5.7%, p<0.001). In this study, practice changes focused towards specific ICUs were associated with decreases in ICU vancomycin use and VRE prevalence.

[Antimicrobial use in Spanish hospitals (EPINE, 1990-1999)]

BACKGROUND

Monitoring of antimicrobial use and knowledge of prescription habits are some of the strategies recommended to contain the resistance to antimicrobials in hospitals.

METHOD

We analyzed a series of 10 annual studies of prevalence during the period 1990-1999 (EPINE project) in Spanish hospitals. Estimates of antimicrobial use were calculated as the percent distribution of every antimicrobial related to the overall antimicrobials prescribed.

RESULTS

Among 484,013 hospitalized patients, 34 to 36% were receiving antimicrobials (antibiotics > 90%). Amoxicillin-clavulanate use increased from 3.8% in 1990 up to 14.8% in 1999 (P < 0.01). Significant increases were also observed in the use of carbapenems (0.9 to 2.7%; P < 0.01), glycopeptides (1.7 to 3.7%; P < 0.01) and quinolones (8.5 to 11.3%; P < 0.01) though to a lesser degree. Conversely, the use of aminoglycosides decreased over the decade studied (15.8 to 9.4%; P < 0.01).

CONCLUSIONS

Even though the use of antimicrobials has increased over the last decade, current figures are within the ranges observed in other countries. The pattern of antibiotics use has changed during this period: while the use of aminoglycosides decreased, that of -lactams plus -lactamase inhibitors, quinolones and carbapenems increased.

[Spread of Enterobacteriaceae producing broad-spectrum beta-lactamase and the development of their incidence over a 16-month period in a university hospital center]

Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBLE) constitute with methicillin-resistant Staphylococcus aureus the main multiresistant bacteria recovered in French hospitals. Our objectives were to evaluate these ESBLE diffusion in our teaching hospital and to follow their incidence during a 16-month period, whereas a control programme (barrier precautions) had been implemented in the beginning of 1999. This study was conducted in a teaching hospital containing 1800 beds, from February 1999 to May 2000. All ESBLE isolated in clinical or screening samples were included. Duplicates (same bacteria in the same patient) were excluded. The detection of the ESBL was performed with the double-disk diffusion test. Incidence densities were determined with their 95% confidence interval (CI95%). Their evolution by four-month period was evaluated with the chi-square test for trend. During the 16-month period, 229 ESBLE were isolated. The incidence was 0.35 per 1000 patient-days (PD) (CI95% = [0.30-0.40]) for the whole hospital. It was 0.47/1000 PD (CI95% = [0.38-0.56]) in medical wards, 0.29/1000 PD (CI95% = [0.20-0.38]) in surgical wards and 1.32/1000 PD (CI95% = [0.90-1.74]) in intensive care units. Enterobacter aerogenes strains represented more than 75% of all ESBLE, whereas Klebsiella pneumoniae stains represented only 8.6%. During the study, the incidence of ESBLE and the proportion of strains acquired in our hospital decreased significantly (p < 0.0001 and p < 0.001 respectively). Indeed, between the first eight-month period and the last one, the incidence of ESBLE acquired in our hospital decreased by 55%, whereas the incidence of imported strains increased slightly. This study shows that the diffusion of ESBLE concerns the entire hospital. The implementation of a control programme of the spread of multiresistant bacteria allowed us to reduce significantly the incidence of ESBLE. This incidence seemed to be stable for several months. The implementation of a policy which restricts antimicrobial use would allow us to complete the the efficacy of barrier precautions.

Detection of multiresistant ceftazidime-susceptible Klebsiella pneumoniae isolates lacking TEM-26 after class restriction of cephalosporins

A multitude of extended spectrum beta-lactamases (ESBLs) have evolved in response to the use of late generation cephalosporins. In those hospitals where Klebsiella pneumoniae and other bacteria possessing these enzymes flourish, many interventions have been applied to reduce this trend. We instituted a policy of class restriction of cephalosporins in our hospital in 1996 that led to a 44% reduction in ceftazidime-resistant K. pneumoniae hospital-wide and an 87% decrease in the surgical intensive care unit. Another interesting outcome of this strategy was the identification of multiresistant K. pneumoniae, which was now susceptible to ceftazidime. Characterization of these novel isolates demonstrated that the TEM-26 enzyme, which was responsible for ceftazidime resistance in our earlier described outbreak, was lacking in most of the isolates examined. Among the remaining ceftazidime-resistant K. pneumoniae, TEM-26 was also absent, and new enzymes that hydrolyze ceftazidime were detected. Loss of ceftazidime-hydrolyzing beta-lactamases was observed after in vitro passage of ceftazidime-resistant K. pneumoniae on antibiotic-free media. These findings suggest that class restriction of cephalosporins may increase susceptibility among extended-spectrum beta-lactamase-producing pathogens.

Evaluation of the contribution of isolation precautions in prevention and control of multi-resistant bacteria in a teaching hospital

From February 1999 to January 2000, a control programme to prevent the spread multi-resistant bacteria (MRB) was implemented in a French teaching hospital. This programme focused on methicillin-resistant Staphylococcus aureus (MRSA) and Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBL), and was based on the application of barrier precautions (washing hands with antiseptic soaps, wearing disposable gloves and gowns, identifying MRB carriers). No changes in antibiotic policy occurred during the year. Our aim was to conduct an evaluation of this programme by measuring incidence rates. Concurrently, the effect of barrier precautions was estimated in an indirect way, by documenting the availability of barrier precautions in MRB carriers' rooms and by analysing the monthly correlation between the supply of such material and the theoretical cumulated length of MRB carriers' isolation in six randomized wards. All MRB isolated in hospitalized patients were recorded, and differentiated between acquisition in our hospital or from elsewhere. For the analysis of trends, the year was divided in three periods of four months. Over the year, the global MRB incidence was 1.26 per 1000 patient-days (PD) [95% confidence interval (95%CI)=1.16-1.36]. The MRSA incidence was 0.89 per 1000 PD (95%CI=0.81- 0.97) and the ESBL incidence was 0.38 per 1000 PD (95% CI=0.33-0.43). The MRB incidence decreased significantly in all types of specialties except for surgical wards. The incidence decreased by 17.9% for MRSA, 54.9% for ESBL and 34.8% for both MRB. Concurrently, the proportion of strains acquired in our hospital decreased for MRSA (P for trend > or = 0.05) and ESBL (P for trend > or = 0.01), whereas the incidence of imported strains increased slightly. The proportion of multiresistant strains in S. aureus (36.8%) and Enterobacter aerogenes (37.0%) remained similar throughout the year. Thus, the decrease of the incidence concerned both resistant and susceptible strains. The availability of antiseptic soaps increased significantly (P for trend > or = 0.01). The amount of antiseptic soap ordered and the theoretical lengths of isolation were correlated on a monthly basis (Spearman coefficient = 0.72; P > or = 0.02). These results shows the efficacy of such a programme of MRB containment in a large hospital, provided barrier nursing is instigated, together with the availability of such material as antiseptic soap, to allow implementation.

Quality measures of antimicrobial drug use

Antimicrobial use is the major determinant in the development of resistance. Many parameters of importance for optimal quality of antimicrobial therapy have already been defined. Maximal efficacy of the treatment should be combined with minimal toxicity at the lowest cost. Quality of antimicrobial drug use is dependent on knowledge of many aspects of infectious diseases. Considering efficacy, many of our indications for antimicrobial use need critical evaluation. Irrational use should be discouraged. Avoidance of the development of resistance is a quality parameter that will need increasing attention. This paper reviews the well-established factors that may influence the appropriateness of pharmacotherapy with antimicrobial drugs. It cites recent evidence supporting principles of prudent prescribing and gives an overview of audits that have addressed these parameters. Measures relating to resistance are discussed.

Economic impact of antimicrobial resistance

One reason antimicrobial-drug resistance is of concern is its economic impact on physicians, patients, health-care administrators, pharmaceutical producers, and the public. Measurement of cost and economic impact of programs to minimize antimicrobial-drug resistance is imprecise and incomplete. Studies to describe and evaluate the problem will have to employ new methods and be of large scale to produce information that is broadly applicable.

Rotation and restricted use of antibiotics in a medical intensive care unit. Impact on the incidence of ventilator-associated pneumonia caused by antibiotic-resistant gram-negative bacteria

To test the hypothesis that a new program of antibiotic strategy control can minimize the incidence of ventilator-associated pneumonia (VAP) caused by potentially antibiotic-resistant microorganisms, we performed a prospective before-after study in 3, 455 patients admitted to a single intensive care unit over a 4-yr period. Regarding the bacterial ecology and the increasing antimicrobial resistance in our medical intensive care unit (MICU), we decided to vary our choice of empiric and therapeutic antibiotic treatment, with a supervised rotation, and a restricted use of ceftazidime and ciprofloxacin, which were widely prescribed before this scheduled change. For all patients, VAP was diagnosed based on the results of quantitative culture of bronchoalveolar lavage specimens (>/= 10(4) cfu/ml). We studied 1,044 and 1,022 patients requiring more than 48 h of mechanical ventilation (MV), respectively, in the before-period (2 yr: 1995-1996) and the after-period (2 yr: 1997-1998). We observed a decrease from 231 consecutive episodes of VAP in the before-period to 161 episodes of VAP in the after-period (p < 0.01), particularly for VAP occurring before 7 d of MV. The total number of potentially antibiotic-resistant gram-negative bacilli responsible for VAP such as Pseudomonas aeruginosa, Burkholderia cepacia, Steno-trophomonas maltophilia, and Acinetobacter baumanii decreased from 140 to 79 isolated bacilli. The susceptibilities of these bacteria to the antibiotics regimen increased significantly, especially for P. aeruginosa and B. cepacia. The percentage of methicillin-sensitive Staphylococcus aureus increased significantly from 40% to 60% of S. aureus responsible for VAP. These results suggest that a new strategy of antibiotics use could be an efficient means to reduce the incidence of VAP caused by antibiotic-resistant bacteria. Nevertheless, further studies are needed to validate these data.

Geography is destiny: global nosocomial infection control

The global nature of the emergence and spread of multiresistant bacteria has resulted in a slow response from governmental bodies, but surveillance networks are being set up and there is evidence, cited in this review, of an element of cooperation among professional bodies. Most developed and many developing countries have recognized the need for nosocomial infection control.

The pharmacist's role in promoting optimal antimicrobial use

Optimal use of antimicrobials is essential in the face of escalating antibiotic resistance, and requires cooperation from all sectors of the health care system. Although antibiotic-restriction policies in the hospital setting are important in altering microbial susceptibility patterns, an overall reduction in antibiotic prescriptions in the outpatient setting is more likely to significantly impact antibiotic resistance. Education of providers, application of clinical practice guidelines, audit and feedback activities, and multifaceted interventions all have had an effect in altering antibiotic prescribing in a research setting. Clinicians must alter antibiotic prescribing for the treatment of infectious diseases, and patients must change their perception of the need for these drugs. Pharmacists can play a major role through clinician education and focused clinical services. With cooperation of health care teams, the effectiveness of available antibiotics may be sustained and the threat of resistance minimized.

Modelling and forecasting antimicrobial resistance and its dynamic relationship to antimicrobial use: a time series analysis

To investigate the relationship between antimicrobial use and resistance in our hospital, we collected antimicrobial susceptibility and use data from existing microbiology laboratory and pharmacy databases for the period July 1st, 1991-December 31, 1998. The data was analyzed as time series and autoregressive integrated moving average (Box-Jenkins) and transfer function models were built. By using this method, we were able to demonstrate a temporal relationship between antimicrobial use and resistance, to quantify the effect of use on resistance and to estimate the delay between variations of use and subsequent variations in resistance. The results obtained for two antimicrobial-microorganism combinations: ceftazidime-gram-negative bacilli and imipenem-Pseudomonas aeruginosa, are shown as examples.

Potential role of pharmacokinetics, pharmacodynamics, and computerized databases in controlling bacterial resistance

Bacterial resistance to antibiotics continues to be a problem, in spite of increased knowledge of resistance mechanisms. Due to the multifactorial nature of bacterial resistance, studies that evaluate the association between antimicrobial exposure and emergence of resistance may fail to find a relationship unless other factors, in particular the association between patient-pathogen pharmacokinetics (PK) and pharmacodynamics (PD) and the emergence of bacterial resistance, are evaluated as well. It has been hypothesized that, in conjunction with good infection control practices, cycling of antimicrobial agents may prove to be effective in reducing resistance emergence. There is some indication that there may be a relationship between the level of antibiotic exposure and the probability of emergence of bacterial resistance. As shown in our companion article in this supplement, factors associated with ciprofloxacin resistance in Pseudomonas aeruginosa included increased length of stay prior to isolation, exposure to ciprofloxacin, and respiratory tract site of bacterial isolation. However, in patients who received ciprofloxacin therapy, when exposure was at an area under the 24-hour inhibitory concentration curve (AUIC24)>110 (microg x h/mL)/microg/mL, resistance was decreased to 11%, a rate similar to that seen in respiratory isolates not exposed to ciprofloxacin (7%). While the length of time the patient spends in the hospital and the site of infection cannot be controlled, by using PK and PD principles for dosing of ciprofloxacin, the emergence of ciprofloxacin resistance in P aeruginosa may be reduced. Prospective antibiotic-cycling studies may help to determine not only the impact of antibiotic cycling on the institution's antibiogram but also, through the use of PK and PD principles, may help to determine appropriate dosing schedules for antibiotics in order to reduce the probability of emergence of bacterial resistance.

Epidemiology and risk factors for nosocomial pneumonia. Emphasis on prevention

VAP is a complex nosocomial infection, the disease expression and resulting patient outcome of which is dependent on host factors, the causative organism, the timing and adequacy of treatment, and the presence of intrinsic or inducible antibiotic resistance. Significant improvements have been achieved in our ability to reduce the occurrence of VAP in the hospital setting. Clinicians caring for mechanically ventilated patients should strive to develop focused programs for the prevention of VAP, other nosocomial infections, and the occurrence of antibiotic-resistant infections at their institutions. The benefits of such programs are well demonstrated. The components of a PDSA (Plan-Do-STUDY-Act) model that can be simply employed to develop a VAP prevention program are as follows: Stages Plan: 1. Identify potentially modifiable risk factors for VAP at the institutional level. 2. Develop a strategy to modify or prevent the occurrence of these risk factors. [figure: see text] Do: 1. Carry out the planned intervention strategy. 2. Identify problems in the implementation of the designed intervention. 3. Update the intervention with solutions for the identified problems. 4. Collect basic data (e.g., VAP rates, severity of illness).

STUDY

1. Analyze data. 2. Summarize the results. Act: 1. Determine the overall success or failure of the intervention. 2. Identify potential modifications to improve the intervention strategy. 3. Prepare for next PDSA cycle. Inherent in the development and application of such programs is the concept that they are continuous processes striving to improve clinical performance over time (Fig. 3). At any given institution, the most likely approach to the prevention of NP and VAP will be a multifaceted one, employing interventions aimed at reducing the occurrence of aerodigestive tract colonization with pathogenic bacteria and aspiration. To be successful, such quality improvement programs must be embraced at the institutional level. Only in this way can hospitals hope to successfully reduce their rates of VAP and sustain or improve upon those efforts over time.

Antimicrobial resistance in intensive care units

The unique nature of the intensive care unit (ICU) environment makes this part of the hospital a focus for the emergence and spread of many antimicrobial-resistant pathogens. There are ample opportunities for the cross-transmission of resistant bacteria from patient to patient, and patients are commonly exposed to broad-spectrum antimicrobial agents. Rates of resistance have increased for most pathogens associated with nosocomial infections among ICU patients, and rates are almost universally higher among ICU patients compared with non-ICU patients. There are many opportunities, however, to prevent the emergence and spread of these resistant pathogens through improved use of established infection control measures (i.e., patient isolation, hand washing, glove use, and appropriate gown use), and implementation of a systematic review of antimicrobial use.

Intensive Care Antimicrobial Resistance Epidemiology (ICARE) Surveillance Report, data summary from January 1996 through December 1997: A report from the National Nosocomial Infections Surveillance (NNIS) System

The Intensive Care Antimicrobial Resistance Epidemiology project has established laboratory-based surveillance for antimicrobial resistance and antimicrobial use at a subset of hospitals participating in the National Nosocomial Infections Surveillance system. These data illustrate that, for most antimicrobial resistant organisms studied, rates of resistance were highest in the intensive care unit areas and lowest in the outpatient areas. For most of the antimicrobial agents, the rate of use was highest in the intensive care unit areas in parallel to the pattern seen for resistance. These comparative data on antimicrobial use and resistance among similar areas (ie, intensive care unit or other inpatient areas) can be used as a benchmark by participating hospitals to focus their efforts at addressing antimicrobial resistance.

A review of the role of antibiotic policies in the control of antibiotic resistance

The optimal antibiotic control measures remain to be described and probably vary between institutions. Nevertheless, various control measures have been shown to be useful in reducing costs of therapy and total amounts of prescribing, while maintaining quality of care. More recently, interest has turned to whether antibiotic policies can reduce the spread of resistance and even reverse current high levels. Early studies indicated this was feasible, but mathematical models and the recent discovery of the role of transposons and integrons in multi-drug resistance have both cast doubt on likely future success in this area. Nevertheless, there have been some major successes in recent studies, both in the community and hospital. While cross-infection is a major impediment to control of resistance, there is little doubt that careful antibiotic prescribing can curtail the emergence and reduce the prevalence of resistance.

Vancomycin-resistant enterococci: the clinical effect of a common nosocomial pathogen

Enterococcus spp. is now the third most common pathogen among hospitalized patients, accounting for nearly 12% of nosocomial infections. Enterococcus faecalis is the most prevalent enterococcal species (85%-89%), whereas Enterococcus faecium accounts for 10%-15% of enterococcal isolates. Only 5% of E. faecalis isolates are resistant to glycopeptides. E. faecium has also been shown to be resistant to nonglycopeptide compounds, such as penicillins (97%), high-level gentamicin (52.1%), and high-level streptomycin (58.3%). Numerous risk factors for vancomycin-resistant enterococci (VRE) have been identified, including as length of hospital- or ICU-stay, proximity to a hospitalized, colonized VRE, patient severity of illness, renal failure, recent surgery, immunosuppression, and organ recipient status. An important risk factor is prior exposure to antibiotics such as vancomycin, ceftazidime, ciprofloxacin, and metronidazole, as well as the number and duration of recent antibiotics. Interventions to reduce nosocomial VRE cross-transmission have also been studied. Using gowns in addition to gloves diminished the incidence of VRE in one study, but had a negligible effect in a second study. Studies have shown that in many cases (> 60%) vancomycin usage is inappropriate. While controlling the use of vancomycin alone has only variably diminished VRE colonization, other efforts such as narrowing the spectrum of antibiotics, antiseptics, and reducing immunosuppression may be salutary. Attempts to eradicate VRE intestinal carriage with enteral agents (bacitracin, tetracycline + rifampin, novobiocin) have been reported but seem to have only a transient effect. Non-antimicrobial interventions such as removal of intravenous or bladder catheters and/or surgical or percutaneous drainage may be beneficial. In addition, the development of new antimicrobial agents such as streptogramins, glycopeptides, everninomicins, and oxazalididones will hopefully play an important role in reducing morbidity from these pathogens.

Pathogens, old and new: an update for cardiovascular nurses

Infectious diseases remain the major cause of death throughout the world, and this is not likely to change in the foreseeable future. However, there are steps that can be taken to combat them, including both the recognition of and interventions against emerging infectious diseases. This article will provide general information about emerging infectious organisms, mechanisms of resistance to antimicrobial agents, and comments on a variety of prevention strategies. In addition, the reader is directed to a number of comprehensive references for additional information.

Epidemiology of a dominant clonal strain of vancomycin-resistant Enterococcus faecium at separate hospitals in Boston, Massachusetts

In 1996, the dominant (43%) strain of vancomycin-resistant enterococci (VRE; type A) at Massachusetts General Hospital was identified at Brigham and Women's Hospital (BWH). To characterize the epidemiology of infection with type A isolates of VRE at BWH, we collected demographic and clinical data for all patients from whom VRE were isolated from a clinical specimen through September 1996. The first clinical isolates from all BWH patients from whom VRE were isolated were typed by pulsed-field gel electrophoresis of SmaI digests of chromosomal DNA. Among patients hospitalized after the first patient at BWH infected with a type A isolate of VRE was identified, exposures were compared between patients who acquired type A isolates of VRE and those who acquired other types of VRE. Isolates from 99 patients identified to have acquired VRE were most commonly from blood (n = 27), urine (n = 19), or wounds (n = 19). Three months after the index patient arrived at BWH and at a time when > or =12 types of strains of VRE were present, type A isolates of VRE became dominant; 39 of 75 (52%) of the study cohort had acquired type A isolates of VRE. We found no association between the acquisition of type A isolates of VRE and transfer from another institution or temporal overlap by service, ward, or floor with patients known to have acquired type A isolates of VRE. By multivariate analysis, only residence in the medical intensive care unit (adjusted odds ratio [OR], 3.2; 95% confidence interval [CI], 1.4 to 107) and the receipt of two or more antibiotics per patient-day (adjusted OR, 12.2; 95% CI, 1.2 to 9.0) were associated with the acquisition of strain A. This strain of VRE, dominant at two Boston hospitals, was associated with intensity of antibiotic exposures (i.e., two or more antibiotics per patient-day). We hypothesize that this strain may have unidentified properties providing a mechanism favoring its spread and dominance over other extant isolates, and further studies are needed to define these properties.