Increasing consumption of MRSA-active drugs without increasing MRSA in German ICUs

The Impact of an Antibiotic Stewardship Program on the Consumption of Specific Antimicrobials and Their Cost Burden: A Hospital-wide Intervention

Background

Inappropriate use of antimicrobials (AM) is a major concern worldwide that leads to the propagation of antimicrobial resistance (AMR). In addition to its clinical implications, AMR imposes an economic burden on communities, especially developing countries with more infectious diseases and less available resources. Antimicrobial stewardship programs (ASPs) have been found to be effective in reducing AMR. This study was designed to evaluate the effect of implementing an ASP in reducing AM consumption, its economic burden, and AMR as a consecutive result.

Materials and Methods

Consumption of caspofungin, amphotericin B, voriconazole, colistin, linezolid, vancomycin, and carbapenems was compared in a prospective cross-sectional study between two time periods introduced as pre- and post-ASP. Drug use density presented as anatomical therapeutic chemical (ATC)/defined daily doses (DDD) and normalized per 1000 bed days, cost savings, and AMR patterns were evaluated.

Results

A total of 9400 AM prescriptions were analyzed during a 2-year period. Consumption measured in DDD/1000 bed days dropped by 24.8, 25.0, 35.3, 47.0, 39.2, 10.5, and 23.2 percent for amphotericin B, caspofungin, colistin, voriconazole, meropenem, imipenem, and vancomycin, respectively. Linezolid consumption increased by 26.8% after implementing ASP. The expenditure of target AMs in the average value of USD decreased by 41.3% after the intervention compared to the time before using ASP (P-value=0.001). Implementing ASP also increased AM susceptibility of Pseudomonas aeruginosa, while the susceptibility of methicillin-resistant Staphylococcus aureus did not change significantly.

Conclusion

The results of this study suggest that establishment of ASP can lead to a reduction in improper administration of AMs and their expenditure resulting in economic benefit and lowering AMR at hospitals with minimum resources. Clinical pharmacists' role was critical to the success of this ASP and was uniquely empowered at our center.

Prediction of methicillin-resistant Staphylococcus aureus bloodstream infection: do we need rapid diagnostic tests?

Staphylococcus aureus (SA) is the leading cause of bloodstream infection (BSI). The incidence of methicillin-resistant SA (MRSA) has decreased in France and Europe since one decade. Early and precise prediction of methicillin susceptibility is needed to improve probabilistic antibiotic therapy of MRSA-BSI. The aim of this study was to identify MRSA-BSI risk factors at admission and evaluate which patients need costly rapid diagnostic tests. A single-center retrospective descriptive study of all diagnosed SA-BSI was conducted in a French University Hospital between January 2015 and December 2016. All medical charts were reviewed. Univariate and multivariate analyses by a logistic regression model were performed on the data. We then build a prediction score of MRSA-BSI by assigning one point for each of the risk factor identified. During the study period, 151 SA-BSI were identified including 32 (21%) MRSA-BSI. In multivariate analysis, three factors were associated with MRSA-BSI: coming from long-term care facility, known previous MRSA colonization and/or infection, and chronic renal disease. Among our population, respectively, 5% and 100% had a MRSA-BSI when no or three risk factors were identified. Therefore, among the PCR performed, 43 (96%) could be avoided according to our clinical score. In our study, methicillin-susceptible SA and MRSA-BSI can be predictable by counting MRSA risk factors. This prediction rule could avoid the use of expensive rapid diagnostic tests. Prospective studies and prediction rules could help physicians to predict SA-BSI susceptibility to improve appropriate empiric therapy choice.

Correlation between antibiotic consumption and resistance of bloodstream bacteria in a University Hospital in North Eastern Italy, 2008-2014

PURPOSE

The spread of multidrug-resistant bacteria is a worrisome problem worldwide. This study investigated the correlation between antibiotic consumption and antimicrobial resistance trends of the most important bacteria causing bacteremia at the University hospital of Trieste, Italy, from 2008 to 2014.

METHODS

Antibiotic consumption (Defined Daily Dose-DDD-per 100 patient/days) and antibiotic resistance (percentage of antibiotic intermediate o resistant isolates) were analyzed independently with linear correlation by year. Potential correlations between antibiotic consumption and bacteria resistance rates were investigated through the Pearson's correlation.

RESULTS

The overall consumption of antibiotic grew from 80 to 97 DDD 100 patient/days (p = 0.005) during the study period. The increased consumption of amoxicillin/clavulanate and piperacillin/tazobactam was associated with the reduction of MRSA rate from 48.5 to 25.9% (p = 0.007 and p = 0.04, respectively). The increased consumption of piperacillin/tazobactam was associated with the reduction of ESBL-positive Enterobacteriaceae rate from 28.9 to 20.9% (p = 0.01). The increased consumption of carbapenems was associated with the increased rate of carbapenem-resistant Acinetobacter baumannii from 0 to 96.4% (p = 0.03). No carbapenem-resistant Enterobacteriaceae isolates were reported. The consumption of vancomycin grew significantly (p = 0.005). A dramatic spread of vancomycin-resistant Enterococcus faecium occurred in 2014. The consumption of fluoroquinolones and extended-spectrum cephalosporins remained stable.

CONCLUSIONS

An antibiotic stewardship program targeted to limit the consumption of extended-spectrum cephalosporins and fluoroquinolones in favor of amoxicillin/clavulanate and piperacillin/tazobactam correlates with a decreasing rate of MRSA and ESBL-positive Enterobacteriaceae. The analysis of correlations between antibiotic consumption and bacterial resistance rates is a useful tool to orient antimicrobial stewardship policies at local level.

Relationship between consumption of MRSA-active antibiotics and burden of MRSA in acute care hospitals in Catalonia, Spain

OBJECTIVES

To analyse the possible relationship between consumption of old and new MRSA-active antibiotics and burden of MRSA in acute care hospitals in Catalonia during the period 2007-12.

METHODS

Fifty-four hospitals participating in the VINCat Programme were included. Proportion of MRSA (resistant isolates of Staphylococcus aureus per 100 isolates of S. aureus tested), incidence of new cases of infection [new cases of MRSA per 1000 occupied bed-days (OBD)] and incidence of cases of bacteraemia (MRSA bacteraemia cases per 1000 OBD) were determined to estimate the annual MRSA burden. Antibiotic consumption was calculated in DDD/100 OBD. Cost was expressed in euros/100 OBD.

RESULTS

MRSA rates remained stable over the study period, with the proportion of MRSA ranging from 20% to 22.82% in 2007 and 2012, respectively (P=0.864). Consumption of old MRSA-active antibiotics (vancomycin and teicoplanin) did not change significantly, with values from 1.51 to 2.07 DDD/100 OBD (P=0.693). Consumption of new MRSA-active antibiotics (linezolid and daptomycin) increased significantly, with values rising from 0.24 to 1.49 DDD/100 OBD (P<0.001). Cost increased by almost 200%.

CONCLUSIONS

A widespread and steady increase in consumption of new MRSA-active antibiotics was observed among acute care hospitals in Catalonia, in spite of a stable MRSA burden. At the same time, consumption of old drugs remained stable. Such trends resulted in a significant increase in cost. Our findings suggest that factors other than the proportion of methicillin resistance among S. aureus may influence the use of old and new MRSA-active antibiotics in the clinical setting.

Linezolid plasma and intrapulmonary concentrations in critically ill obese patients with ventilator-associated pneumonia: intermittent vs continuous administration

PURPOSE

Clinical application of an antibiotic's pharmacokinetic/pharmacodynamic (PK/PD) properties may improve the outcome of severe infections. No data are available on the use of linezolid (LNZ) continuous infusion in critically ill obese patients affected by ventilator-associated pneumonia (VAP).

METHODS

We conducted a prospective randomized controlled trial to compare LNZ concentrations in plasma and epithelial lining fluid (ELF), when administered by intermittent and continuous infusion (II, CI), in obese critically ill patients affected by VAP.

RESULTS

Twenty-two critically ill obese patients were enrolled. At the steady state, in the II group, mean ± SD total and unbound maximum-minimum concentrations (C max/C max,u - C min/Cmin,u) were 10 ± 3.7/6.8 ± 2.6 mg/L and 1.7 ± 1.1/1.2 ± 0.8 mg/L, respectively. In the CI group, the mean ± SD total and unbound plasma concentrations (C ss and C ss,u) were 6.2 ± 2.3 and 4.3 ± 1.6 mg/L, respectively. Within a minimum inhibitory concentration (MIC) range of 1-4 mg/L, the median (IQR) time LNZ plasma concentration persisted above MIC (% T > MIC) was significantly higher in the CI than the II group [100 (100-100) vs 100 (89-100), p = 0.05; 100 (100-100) vs 82 (54.8-98.8), p = 0.009; 100 (74.2-100) vs 33 (30.2-78.5), p = 0.005; respectively]. Pulmonary penetration (%) was higher in the CI group, as confirmed by a Monte Carlo simulation [98.8 (IQR 93.8-104.3) vs 87.1 (IQR 78.7-95.4); p < 0.001].

CONCLUSIONS

In critically ill obese patients affected by VAP, LNZ CI may overcome the limits of standard administration but these advantages are less evident with difficult to treat pathogens (MIC = 4 mg/L). These data support the usefulness of LNZ continuous infusion, combined with therapeutic drug monitoring (TDM), in selected critically ill populations.

Population dynamics among methicillin-resistant Staphylococcus aureus isolates in Germany during a 6-year period

Methicillin-resistant Staphylococcus aureus (MRSA) originated from the health care setting but is now emerging in communities without health care contact (CA-MRSA) or in livestock (LA-MRSA). The impact on the whole MRSA population was assessed in a German prospective multicenter study. Thirty-three laboratories consecutively collected up to 50 MRSA isolates from infection or carriage during two sampling periods in 2004 to 2005 and 2010 to 2011. Patient-related data were collected using a standardized questionnaire. Methicillin resistance was confirmed by the detection of mecA or its homologue mecA(LGA251). The spa type and major virulence factors were analyzed for each isolate. In total, 1,604 (2004 to 2005) and 1,603 (2010 to 2011) MRSA isolates were analyzed; one isolate from each sampling period harbored mecA(LGA251). LA-MRSA increased significantly (odds ratio [OR] = 22.67, 95% confidence interval [CI] = 8.51 to 85.49, P < 0.0005) and spread over Germany, originating from northwestern regions. Panton-Valentine leukocidin-positive CA-MRSA rose significantly, particularly in southern Germany, but the proportion in 2010 to 2011 remained low (2.7%, OR = 2.80, 95% CI = 1.54 to 5.34, P < 0.0005). The emerging MRSA clones changed the MRSA population in Germany during a 6-year period significantly. The ongoing epidemiological shift and changes of MRSA sources create a need for revision of guidelines for MRSA infection control and treatment.