The use of systemic antibiotics in seven community hospitals in Northern Israel

A Simulation Study to Assess Indicators of Antimicrobial Use as Predictors of Resistance: Does It Matter Which Indicator Is Used?

OBJECTIVE

Indicators of antimicrobial use have been described previously, but few studies have compared their accuracy in prediction of antimicrobial resistance in hospital settings. This study aimed to identify conditions under which significant differences would be observed in the predictive accuracy of indicators in the context of surveillance of intensive care units (ICUs).

METHODS

Ten resistance / antimicrobial use combinations were studied. We used simulation to determine if Québec's network of 81 ICUs or the National Healthcare Safety Network (NHSN) of 2952 ICUs are large enough to allow the detection of predetermined differences between the most accurate and 1) the second most accurate indicator, and 2) the least accurate indicator, in more than 80% of simulations. For each indicator, we simulated absolute errors in prediction for each ICU and each 4-week period, for surveillance lasting up to 5 years. Absolute errors were generated following a binomial distribution, using mean absolute errors (MAEs) observed in 9 ICUs as the average proportion; simulated MAEs were compared using t-tests. This was repeated 1000 times per scenario.

RESULTS

When comparing the two most accurate indicators, 80% power was reached less often with the Québec network versus the NHSN (0/20 versus 2/20 scenarios, with 5 years of surveillance data), a finding reinforced when comparing the most and least accurate indicators (3/20 versus 20/20 scenarios). When simulating 1 year of data, scenarios reaching an 80% power dropped to 0/20, comparing the two most accurate indicators with the larger network, and to 1/20, comparing the most and least accurate indicators with the smaller network.

CONCLUSION

Most of the time (72%), identifying an indicator of antimicrobial use predicting antimicrobial resistance with a better accuracy was not possible. The choice of an indicator for an eventual surveillance system should rely on criteria other that predictive accuracy.

Antibiotic prescription and cost patterns in a general intensive care unit

Antibiotic prescription habits, cost pattern, and the prospective intervention in an Intensive Care Unit were analyzed.

Methods

Data on antibiotic utilization and costs were collected prospectively from individual electronic charts from August 2003 to January 2004, and retrospectively from August to December 2002.

Results

A total of 180 and 107 patients were surveyed in 2002 and 2003. In 2002, Piperacillin-Tazobactam (13.8%) and Imipenem/Cilastin (11.2%) were the most prescribed medications; while, in 2003, Vancomycin (12.6%) and Imipenem/Cilastin (11.3%) were prescribed, respectively. Total defined daily dose (DDD) and Drug Utilization 90% (DU90%) index for 2002 and 2003 were 2031.15 and 2325.90 DDDs (p>0.1) and 1777.57 and 2079.61 DU90%, respectively (p>0.1). The Median Total Cost /100 admission days (CI 95%) were NIS13,310 (11,110;18,420) and NIS13,860 (6,710;18,020) (p=0.66), respectively.

Conclusions

Interventional programs should focus on promoting infectious control with rational antibiotic prescription aimed at minimizing the future emergence of bacterial resistance and futile expenses.

The use of serial point-prevalence studies to investigate hospital anti-infective prescribing

Objectives

To develop and test an efficient, reproducible method for the surveillance of hospital anti-infective use; to use this method to investigate patterns of anti-infective prescribing.

Method

A series of three standardised point-prevalence studies were carried out in which pharmacists recorded details of all inpatients prescribed systemic anti-infectives. Time taken to collect, enter and analyse these data was documented. Parameters examined included: percentage of patients prescribed anti-infectives, percentage of anti-infectives that were for “reserved” use, percentage of these with appropriate approval, percentage of anti-infectives administered intravenously, duration of therapy, and combinations of anti-infectives used.

Setting

All hospital inpatients in a large National Health Service (NHS) Trust comprising four sites.

Key findings

For each study, an estimated 35 additional hours of pharmacists' time was required for data collection, cleaning and analysis, and 15 hours for data entry. The method developed was easily reproducible and results from the three studies were very similar. Overall, 33 per cent of 2,656 inpatients were prescribed at least one anti-infective (mean 1.7 per patient); 48 per cent of anti-infectives were given intravenously (IV), of which 34 per cent could have been given orally. Of the anti-infectives used, 21 per cent were for “reserved” use. Of these, 65 per cent were used for an approved indication, and 11 per cent were not. The remaining 24 per cent had no indication documented in the medical notes.

Conclusion

This is a practical method for studying hospital anti-infective use in the absence of computerised prescribing. The database produced provides a wealth of information and various targets for intervention have been identified; these can now be evaluated against the baseline data collected. The methods developed could be used in other hospitals to provide benchmarking data.

The effect of systemic antibiotics on the microbiological diagnosis of experimental foreign body infections caused by S taphylococcus epidermidis

Qualitative broth culture and quantitative culture on agar were compared with quantitative polymerase chain reaction (PCR) for the diagnosis of foreign body infections (FBI) in a rat model with and without exposure to systemic antibiotics (teicoplanin and rifampin). The 3 methods had a similar and high yield without antibiotics. Antibiotics decreased the number of CFU/foreign body and increased the number of culture-negative foreign bodies and the variability of the results in quantitative culture. The yield of broth culture remained high under antibiotics although prolonged incubation (2-5 days) was required. The yield of the PCR was equivalent or even superior (for teicoplanin) to the yield of broth culture. Quantitative PCR had a higher yield and lower variability than quantitative culture and was not affected by antibiotics. The simultaneous isolation of RNA from all samples indicated viability of the bacteria. Quantitative PCR seems a promising method for the diagnosis of FBI.

Antimicrobial Utilization Pattern in a Hematologic Intensive Care Unit

Background:

Recently, a new method for assessing the quality of prescription — The drug utilization 90% index (DU-90%) — Was introduced. The defined daily dose (DDD) concept is an established parameter in pharmacoepidemiologic studies.

Objective:

To evaluate antibiotic utilization in a specialized hospital unit where the use of antibiotics in immune-compromised patients undergoing intensive chemotherapy or bone marrow transplantation may be one of the main components in the direct cost of therapy of this type of patient.

Methods:

The antibiotic utilization pattern and accompanying costs were prospectively measured for 48 patients in a hematologic intensive care unit during a 60-day period, accumulating 896 admission days of follow-up. The DU-90% level is arbitrarily chosen as a reasonable cutoff point; it concentrates on the bulk of the prescribed antibiotics.

Results:

Of 26 antimicrobial agents prescribed, 14 were included in the DU-90%. Amphotericin B was delivered to 100% of the study population, with a total of 57.99 DDD/100 admission days. Ceftriaxone was the antimicrobial least prescribed, with a total of 0.22 DDD/100 admission days. The DU-90% index showed that 53% of the prescribed medications equal 92% of the total antibiotic cost. A discrepancy between the pharmacy's report and the calculated costs based on DDDs was observed. Failure to have a real-time inventory and costs unification, the use of mean instead of median acquisition costs, and failure to use electronic prescription systems are the main elements affecting and disrupting drug utilization studies. This possibly explains, in part, the difference between the two cost reports.

Piperacillin/tazobactam: a pharmacoeconomic review of its use in moderate to severe bacterial infections

Piperacillin/tazobactam is a beta-lactam/beta-lactamase inhibitor combination with a broad spectrum of antibacterial activity against most Gram-positive and Gram-negative aerobic bacteria and anaerobic bacteria. Piperacillin/tazobactam is effective and well-tolerated in patients with lower respiratory tract infections (LRTI), intra-abdominal infections, skin and soft tissue infections, and febrile neutropenia. In comparative clinical trials against various other antibacterial regimens, piperacillin/tazobactam has shown higher clinical success rates, particularly in the treatment of patients with intra-abdominal infections and febrile neutropenia. Cost analyses of piperacillin/tazobactam have been variable, in part, because of differences in specific costs included. Three US cost analyses found that piperacillin/tazobactam had lower total medical costs than clindamycin plus gentamicin or imipenem/cilastatin in intra-abdominal infections, and ticarcillin/ clavulanic acid in community-acquired pneumonia. Piperacillin/tazobactam plus amikacin had lower total costs than ceftazidime plus amikacin in another cost analysis of patients with febrile neutropenic episodes modelled in nine European countries. However, piperacillin/tazobactam plus tobramycin was more costly than ceftazidime plus tobramycin in hospital-acquired pneumonia in a US cost analysis. In cost-effectiveness analyses, all studies of intra-abdominal infections, pneumonia and febrile neutropenic episodes consistently reported lower costs per unit of effectiveness versus comparators. Piperacillin/tazobactam was dominant (greater efficacy and lower costs) versus imipenem/cilastatin in intra-abdominal infections and ceftriaxone, ciprofloxacin or meropenem in pneumonia. Piperacillin/tazobactam plus amikacin was dominant over ceftazidime plus amikacin in the treatment of febrile neutropenic episodes. In a cost-effectiveness analysis of skin and soft tissue infection, piperacillin/tazobactam had lower costs per successfully treated patient than ceftriaxone or cefotaxime, but a slightly higher cost-effectiveness ratio than amoxicillin/clavulanic acid. All cost-effectiveness analyses were based on decision-analytical models.

CONCLUSIONS

Piperacillin/tazobactam is likely to reduce overall treatment costs of moderate to severe bacterial infections by increasing initial treatment success, thereby reducing the length of hospital stay and the use of additional antibacterials. Piperacillin/tazobactam has shown clinical and economic advantages over standard antibacterial regimens in the treatment of intra-abdominal infections, LRTIs, febrile episodes in patients with neutropenia, and skin and soft tissue infections, although more complete published data are needed to confirm these results. Present data regarding clinical efficacy, bacterial resistance and costs would support the use of piperacillin/tazobactam as an empirical first-line option in moderate to severe bacterial infections.