Consumption of imipenem correlates with beta-lactam resistance in Pseudomonas aeruginosa

Implementation of an Automated Antibiotic Time-out at a Comprehensive Cancer Center

Background

Antimicrobial stewardship programs can optimize antimicrobial use and have been federally mandated in all hospitals. However, best stewardship practices in immunocompromised patients with cancer are not well established.

Methods

An antimicrobial time out, in the form of an email, was sent to physicians caring for hospitalized patients reaching 5 days of therapy for targeted antimicrobials (daptomycin, linezolid, tigecycline, vancomycin, imipenem/cilastatin, meropenem) in a comprehensive cancer center. Physicians were to discontinue the antimicrobial if unnecessary or document a rationale for continuation. This is a quasi-experimental, interrupted time series analysis assessing antimicrobial use during the following times: period 1 (before time-out: January 2007-June 2010) and period 2 (after time-out: July 2010-March/2015). The primary antimicrobial consumption metric was mean duration of therapy. Days of therapy per 1000 patient-days were also assessed.

Results

Implementation of the time-out was associated with a significant decrease in mean duration of therapy for the following antimicrobials; daptomycin: -0.89 days (95% confidence interval [CI], -1.38 to -.41); linezolid: -0.89 days (95% CI, -1.27 to -.52); meropenem: -0.97 days (95% CI, -1.39 to -.56); tigecycline: -1.41 days (95% CI, -2.19 to -.63); P < .001 for each comparison. Days of therapy/1000 patient-days decreased significantly for meropenem (-43.49; 95% CI, -58.61 to -28.37; P < .001), tigecycline (-35.47; 95% CI, -44.94 to -26.00; P < .001), and daptomycin (-9.47; 95% CI, -15.25 to -3.68; P = .002).

Discussion

A passive day 5 time-out was associated with reduction in targeted antibiotic use in a cancer center and could potentially be successfully adopted to several settings and electronic health records.

Impact of Antibiotics Used for Acute Aspiration Bronchitis on the Prevention of Pneumonia

BACKGROUNDS

It remains unclear if antibiotics should be used for the treatment of acute aspiration bronchitis to prevent the development of pneumonia. This study aimed to assess the associations between the use of antibiotics and the development of pneumonia among patients with acute aspiration bronchitis.

METHODS

We retrospectively reviewed consecutive patients with acute aspiration bronchitis aged ≥75 years. Acute aspiration bronchitis was defined as a condition with aspiration risk, high fever (body temperature, ≥37.5 °C), respiratory symptoms, and the absence of evidence of pneumonia.

RESULTS

There was no significant difference in the incidence of pneumonia between patients treated with and without antibiotics for acute aspiration bronchitis (6/44, 14% vs. 31/143, 22%; p = 0.242). Lower estimated glomerular filtration rate (adjusted odds ratio, 0.956; 95% confidence interval, 0.920-0.993) was significantly associated with the development of pneumonia.

CONCLUSIONS

Antibiotic administration should not be routinely recommended to prevent pneumonia following acute aspiration bronchitis, and patients with decreased renal function should be closely monitored. A randomized controlled trial is necessary to validate these results.

Antibiotics in anesthesia and critical care

Sepsis is life-threatening organ dysfunction due to a dysregulated host response to an underlying acute infection. Sepsis is a major worldwide healthcare problem. An annual estimated 48.9 million incident cases of sepsis is reported, with 11 million (20%) sepsis-related deaths. Administration of appropriate antimicrobials is one of the most effective therapeutic interventions to reduce mortality. The severity of illness informs the urgency of antimicrobial administration. Nevertheless, even used properly, they cause adverse effects and contribute to the development of antibiotic resistance. Both inadequate and unnecessarily broad empiric antibiotics are associated with higher mortality and also select for antibiotic-resistant germs. In this narrative review, we will first discuss important factors and potential confounders which may influence the occurrence of surgical site infection (SSI) and which should be considered in the provision of perioperative antibiotic prophylaxis (PAP). Then, we will summarize recent advances and perspectives to optimize antibiotic therapy in the intensive care unit (ICU). Finally, the major role of the microbiota and the impact of antimicrobials on it will be discussed. While expert recommendations help guide daily practice in the operating theatre and ICU, a thorough knowledge of pharmacokinetic/pharmacodynamic (PK/PD) rules is critical to optimize the management of complex patients and minimize the emergence of multidrug-resistant organisms.

Usefulness of dynamic regression time series models for studying the relationship between antimicrobial consumption and bacterial antimicrobial resistance in hospitals: a systematic review

BACKGROUNG

Antimicrobial resistance (AMR) is on the rise worldwide. Tools such as dynamic regression (DR) models can correlate antimicrobial consumption (AMC) with AMR and predict future trends to help implement antimicrobial stewardship programs (ASPs).

MAIN BODY

We carried out a systematic review of the literature up to 2023/05/31, searching in PubMed, ScienceDirect and Web of Science. We screened 641 articles and finally included 28 studies using a DR model to study the correlation between AMC and AMR at a hospital scale, published in English or French. Country, bacterial species, type of sampling, antimicrobials, study duration and correlations between AMC and AMR were collected. The use of β-lactams was correlated with cephalosporin resistance, especially in Pseudomonas aeruginosa and Enterobacterales. Carbapenem consumption was correlated with carbapenem resistance, particularly in Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii. Fluoroquinolone use was correlated with fluoroquinolone resistance in Gram-negative bacilli and methicillin resistance in Staphylococcus aureus. Multivariate DR models highlited that AMC explained from 19 to 96% of AMR variation, with a lag time between AMC and AMR variation of 2 to 4 months. Few studies have investigated the predictive capacity of DR models, which appear to be limited.

CONCLUSION

Despite their statistical robustness, DR models are not widely used. They confirmed the important role of fluoroquinolones, cephalosporins and carbapenems in the emergence of AMR. However, further studies are needed to assess their predictive capacity and usefulness for ASPs.

Correlation between antibiotic use and antibiotic resistance: A multicenter study using the Japan Surveillance for Infection Prevention and Healthcare Epidemiology (J-SIPHE) system in Hokkaido, Japan

BACKGROUND

The Japan Surveillance for Infection Prevention and Healthcare Epidemiology (J-SIPHE) system aggregates information related to antimicrobial resistance (AMR) measures in participating medical institutions nationwide and is intended to be used for promotion of AMR measures in participating facilities and their communities. This multicenter study aimed to determine the usefulness of the J-SIPHE system for evaluating the correlation between antibiotic use and antibiotic resistance in Hokkaido, Japan.

METHODS

Data on antibiotic use and detection rate of major resistant Gram-negative bacteria at 19 hospitals in 2020 were collected from the J-SIPHE system, and data correlations were analyzed using JMP Pro.

RESULTS

The detection rate of carbapenem-resistant Pseudomonas aeruginosa was significantly positively correlated with carbapenem use (Spearman's ρ = 0.551; P = .015). There were significant positive correlations between the detection rate of fluoroquinolone-resistant Escherichia coli and the use of piperacillin/tazobactam, carbapenems, and quinolones [ρ = 0.518 (P = .023), ρ = 0.76 (P < .001), and ρ = 0.502 (P = .029), respectively].

CONCLUSIONS

This is the first multicenter study to investigate the correlation between antibiotic use and antibiotic resistance using the J-SIPHE system. The results suggest that using this system may be beneficial for promoting AMR measures.

Systematic review of time lag between antibiotic use and rise of resistant pathogens among hospitalized adults in Europe

Background

Antimicrobial resistance (AMR) causes substantial health and economic burden to individuals, healthcare systems and societies globally. Understanding the temporal relationship between antibiotic consumption and antibiotic resistance in hospitalized patients can better inform antibiotic stewardship activities and the time frame for their evaluation.

Objectives

This systematic review examined the temporal relationship between antibiotic use and development of antibiotic resistance for 42 pre-defined antibiotic and pathogen combinations in hospitalized adults in Europe.

Methods

Searches in MEDLINE, Embase, Cochrane Library and NIHR Centre for Reviews and Dissemination were undertaken from 2000 to August 2021. Pathogens of interest were Escherichia coli, Klebsiella pneumoniae, Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus faecium, CoNS, Pseudomonas aeruginosa and Acinetobacter baumannii complex.

Results

Twenty-eight ecological studies and one individual-level study were included. Ecological studies were predominantly retrospective in design (19 studies) and of reasonable (20 studies) to high (8 studies) methodological quality. Of the eight pathogens of interest, no relevant data were identified for S. pneumoniae and CoNS. Across all pathogens, the time-lag data from the 28 ecological studies showed a similar pattern, with the majority of studies reporting lags ranging from 0 to 6 months.

Conclusions

Development of antibiotic resistance for the investigated antibiotic/pathogen combinations tends to occur over 0 to 6 months following exposure within European hospitals. This information could inform planning of antibiotic stewardship activities in hospital settings.

SPREAD: An ensemble predictor based on DNA autoencoder framework for discriminating promoters in Pseudomonas aeruginosa

Regulatory elements in DNA sequences, such as promoters, enhancers, terminators and so on, are essential for gene expression in physiological and pathological processes. A promoter is the specific DNA sequence that is located upstream of the coding gene and acts as the "switch" for gene transcriptional regulation. Lots of promoter predictors have been developed for different bacterial species, but only a few are designed for Pseudomonas aeruginosa, a widespread Gram-negative conditional pathogen in nature. In this work, an ensemble model named SPREAD is proposed for the recognition of promoters in Pseudomonas aeruginosa. In SPREAD, the DNA sequence autoencoder model LSTM is employed to extract potential sequence information, and the mean output probability value of CNN and RF is applied as the final prediction. Compared with G4PromFinder, the only state-of-the-art classifier for promoters in Pseudomonas aeruginosa, SPREAD improves the prediction performance significantly, with an accuracy of 0.98, recall of 0.98, precision of 0.98, specificity of 0.97 and F1-score of 0.98.

Trends and Correlation Between Antimicrobial Resistance and Antibiotics Consumption in a Specialist Children’s Hospital from 2016 to 2021

Purpose

To explore the trends and correlation between antibiotics consumption and antimicrobial resistance in children in a specialist hospital from 2016–2021 in China.

Patients and Methods

This retrospective study investigated data on the consumption of antibiotics and antimicrobial resistance in children. Antibiotics consumption was expressed as defined daily doses (DDDs)/1000 patient-days based on the Guidelines for Anatomical Therapeutic Chemical. The trends in antibiotics consumption and antimicrobial resistance rates were analyzed by linear regression, while Spearman correlation analysis was employed to evaluate their correlations.

Results

An increasing trend in the annual consumption of carbapenems and monobactams was detected (all P<0.05). A significant upward trend was detected in the annual resistance rates of Enterococcus faecium to ciprofloxacin, Streptococcus pneumonia to ceftriaxone, Acinetobacter baumannii to carbapenems, Enterobacter cloacae to carbapenems, Pseudomonas aeruginosa to ceftazidime, and Escherichia coli to cefepime, while the annual resistance rates of Escherichia coli to carbapenems had a significant downward trend (all P<0.05). The consumption of cephalosporin/β-lactamase inhibitor (C/BLI) combinations and carbapenems had significant positive correlations with the resistance rates of Acinetobacter baumannii to carbapenems (r=0.763, P<0.001; r=0.806, P<0.001), Enterobacter cloacae to carbapenems (r=0.675, P<0.001; r=0.417, P=0.043), and Pseudomonas aeruginosa to ceftazidime (r=0.625, P=0.001; r=0.753, P<0.001), respectively. Also, increasing consumption of monobactams was related to the upward resistance rates of Acinetobacter baumannii to carbapenems (r=0.557, P=0.005) and Enterobacter cloacae to carbapenems (r=0.507, P= 0.011).

Conclusion

This study demonstrated significant positive associations between antibiotics consumption and specific antimicrobial resistance rates. The current findings pointed out some directions to pursue in controlling the prevalence of certain resistant bacterial strains in children.

Impact of an antibiotic stewardship programme in a surgical setting

Background

Antibiotics are miracles of science and critical for many surgical procedures. However, the emergence of multidrug resistant pathogens resulting from inappropriate antibiotic use is a threat to modern medicine. This study aimed to determine the appropriateness of antibiotic use, cost, consumption and impact of an antibiotic stewardship intervention round in a surgical ward setting.

Methods

Baseline antibiotic utilisation was determined with a retrospective cross-sectional study in two surgical wards in a tertiary academic hospital in South Africa where medical records of 264 patients who received antibiotics were reviewed. In the second stage of the study, records of 212 patients who received antibiotics were reviewed during a weekly antibiotic stewardship intervention round. The volume of antibiotics consumed was determined using defined daily doses (DDDs)/1000 patients' days, and the appropriateness of the antibiotic prescription for treatment was also determined using a quality-of-use algorithm.

Results

There was a reduction in the volume of antibiotic consumption from a total 739.30 DDDs/1000 to 564.93 DDDs/1000 patient days, with reduction in inappropriate antibiotic use from 35% to 26% from baseline to antibiotic stewardship programme stages, respectively. There was an overall increase in culture targeted therapy in both wards in the antibiotic stewardship programme stage.

Conclusion

The implementation of an antibiotic stewardship programme led to a reduction in antibiotic consumption and improvement in appropriate use of antibiotics.

Association of Antibiotic Use with the Resistance Epidemiology of Pseudomonas aeruginosa in a Hospital Setting: A Four-Year Retrospective Time Series Analysis

Background: Even though, Pseudomonas aeruginosa is a common cause of hospital-acquired infections, treatment is challenging because of decreasing rates of susceptibility to many broad-spectrum antibiotics. Methods: Consumption data of eight broad spectrum antimicrobial agents and resistance rates of P. aeruginosa were collected for 48 consecutive months. Autoregressive integrated moving average (ARIMA) and transfer functions models were used to develop relationships between antibiotic use and resistance. Results: Positive correlations between P. aeruginosa resistance and uses of ciprofloxacin (p < 0.001), meropenem (p < 0.001), and cefepime (p = 0.005) were identified. Transfer function models showed the quantified effect of each of these antibiotics on resistance. Regarding levofloxacin, ceftazidime, piperacillin/tazobactam and imipenem, no significant relationships were found. For ceftazidime and levofloxacin, this was probably due to their low consumption, while for imipenem the reason can possibly be ascribed to the already high established P. aeruginosa resistance in the hospital. Conclusion: In the hospital setting, the effect of antimicrobial agents’ consumption on the susceptibility epidemiology of P. aeruginosa differs significantly for each one of them. In this study, the role of precedent use of meropenem, cefepime and ciprofloxacin was quantified in the development of P. aeruginosa resistance.

Decomposition process of cefotaxime sodium from antibiotic wastewater by Up-flow Blanket Filter (UBF) reactor: Reactor performance, sludge characteristics and microbial community structure analysis

In this study, a novel Up-flow Blanket Filter (UBF) reactor was applied to the degradation of antibiotic wastewater. The experiments showed that when the hydraulic retention time (HRT) was 24 h and the ratio of volatile fatty acids (VFA) to alkalinity (ALK) was 0.3, the best removal efficiency was achieved in the combined packing UBF reactor, and the COD removal efficiency reached 80.1%-84.6%, exhibiting a significant difference in reaction performance from the other two reactors (P < 0.05) and a good efficiency of cefotaxime sodium removal. Moreover, the microstructure and surface characteristics of the reactor fillers were studied through scanning electron microscope (SEM) analysis, which showed that three fillers all had biofilm adhesion, but the combined packing gave best performance. Energy dispersive spectrometer (EDS) tests indicated abundant element components in the combined packing. The particle size distribution of sludge was also considered in the experiment, and the result showed the particle size of sludge increased with the operation of the reactor. In addition, microbial community structures of sludge and biofilm with the combined packing were analyzed. High-throughput sequencing confirmed the existence of Pseudomonas, which had good adaptability to antibiotic wastewater and became the dominant bacteria. Decomposition process of cefotaxime sodium after hydrolysis and anaerobic treatment was analyzed through Fourier transform infrared spectroscopy (FTIR). The reactor, which is economical, exhibited favorable performance in degrading the pollutions in the antibiotic wastewater.

Utilization of Vector Autoregressive and Linear Transfer Models to Follow Up the Antibiotic Resistance Spiral in Gram-negative Bacteria From Cephalosporin Consumption to Colistin Resistance

Background

Increasing antibiotic resistance may reciprocally affect consumption and lead to use of broader-spectrum alternatives; a vicious cycle that may gradually limit therapeutic options. Our aim in this study was to demonstrate this vicious cycle in gram-negative bacteria and show the utility of vector autoregressive (VAR) models for time-series analysis in explanatory and dependent roles simultaneously.

Methods

Monthly drug consumption data in defined daily doses per 100 bed-days and incidence densities of gram-negative bacteria (Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, and Acinetobacter baumannii) resistant to cephalosporins or to carbapenems were analyzed using VAR models. These were compared to linear transfer models used earlier.

Results

In case of all gram-negative bacteria, cephalosporin consumption led to increasing cephalosporin resistance, which provoked carbapenem use and consequent carbapenem resistance and finally increased colistin consumption, exemplifying the vicious cycle. Different species were involved in different ways. For example, cephalosporin-resistant Klebsiella spp. provoked carbapenem use less than E. coli, and the association between carbapenem resistance of P. aeruginosa and colistin use was weaker than that of A. baumannii. Colistin use led to decreased carbapenem use and decreased carbapenem resistance of P. aeruginosa but not of A. baumannii.

Conclusions

VAR models allow analysis of consumption and resistance series in a bidirectional manner. The reconstructed resistance spiral involved cephalosporin use augmenting cephalosporin resistance primarily in E. coli. This led to increased carbapenem use, provoking spread of carbapenem-resistant A. baumannii and consequent colistin use. Emergence of panresistance is fueled by such antibiotic-resistance spirals.

Ventilator-associated pneumonia related to ESBL-producing gram negative bacilli

Ventilator-associated pneumonia (VAP) is one of the most frequent cause of intensive care unit (ICU) acquired infections. The worldwide spreading of extended spectrum beta-lactamase producing enterobacteriaceae (ESBL-PE) represents a major problem encountered more and more frequently in ICU. Among ICU patients, between 5% to 25% are ESBL-PE carriers. Whereas, previous carriage is the major risk factors associated with VAP related to ESBL-PE, among carriers, only 5% to 20% will develop a VAP related to ESBL-PE. Also, diagnosis and therapeutic delay are associated with length of stay and higher morbidity, and mortality, therefore, early identification of patients at risk of ESBL-PE related infections is crucial for early implementation of effective antibiotic therapy. VAP related to ESBL-PE should be considered in: previous colonized patients in case of late onset pneumonia and/or when several antibiotic courses precede the infectious episode or even in patients with shock. Among non-colonized patients, if VAP occurs, the risk being related to ESBL-PE is less than 1%. In the future, new rapid microbiological diagnostic tests will allow an early diagnosis. According to recent data, empirical antibiotic therapy should be based on carbapenems. Other alternative antibiotic classes could be used for de-escalation. However, several pharmacodynamic and pharmacokinetics precautions should be taken to achieve drug concentrations at site of infection and except to cure the infected patient.

Antimicrobial prescribing patterns of surgical speciality in a tertiary care hospital in India: Role of persuasive intervention for changing antibiotic prescription behaviour

BACKGROUND

Inappropriate use of antibiotics globally has been linked to increase in antibiotic resistance.

OBJECTIVES

This interventional study assessed the impact of antibiotic prescription feedback and focus group discussions (FGD) on hospital-based prescribers before and after the FGD.

STUDY DESIGN

The present study was performed at a tertiary care centre in New Delhi, wherein 45 units from surgical specialities were included for FGD. Thirty-five units were assessed for the antibiotic usage during 12 months pre-intervention and 3 and 6 months post-intervention period. The outcome measured was a change in antibiotic prescription rates reflected as daily defined doses per 100 bed days as defined by the World Health Organisation.

RESULTS

Reduction in the level of antibiotic consumption was observed in 15 of 35 units (42.85%) during the 3 months post-intervention period, which was significant (P < 0.05) in 3/35 (8.57%) surgical units. A significant reduction (P < 0.05) was observed for the units of endoscopic gynaecology, super-speciality and transplant surgery units B and C, and orthopaedic unit C during the 6 months period. Decreasing trend (P < 0.05) was observed in 2/35 (5.71%) units during the entire period. Overall reduction of antibiotic consumption (1.88%) was observed, with an increase in the use of low-end antibiotics and a decrease in the use of high-end antibiotics.

CONCLUSION

The present study clearly demonstrates a weak impact of FGD in changing antibiotic prescribing behaviour. Further analysis of the sustainability of FGD and its long-term impact on antimicrobial resistance needs to be evaluated. The effect of continuous educational sessions and multifaceted interventions cannot be ignored.

The impact of antibiotic use on transmission of resistant bacteria in hospitals: Insights from an agent-based model

Extensive antibiotic use over the years has led to the emergence and spread of antibiotic resistant bacteria (ARB). Antibiotic resistance poses a major threat to public health since for many infections antibiotic treatment is no longer effective. Hospitals are focal points for ARB spread. Antibiotic use in hospitals exerts selective pressure, accelerating the spread of ARB. We used an agent-based model to explore the impact of antibiotics on the transmission dynamics and to examine the potential of stewardship interventions in limiting ARB spread in a hospital. Agents in the model consist of patients and health care workers (HCW). The transmission of ARB occurs through contacts between patients and HCW and between adjacent patients. In the model, antibiotic use affects the risk of transmission by increasing the vulnerability of susceptible patients and the contagiousness of colonized patients who are treated with antibiotics. The model shows that increasing the proportion of patients receiving antibiotics increases the rate of acquisition non-linearly. The effect of antibiotics on the spread of resistance depends on characteristics of the antibiotic agent and the density of antibiotic use. Antibiotic's impact on the spread increases when the bacterial strain is more transmissible, and decreases as resistance prevalence rises. The individual risk for acquiring ARB increases in parallel with antibiotic density both for patients treated and not treated with antibiotics. Antibiotic treatment in the hospital setting plays an important role in determining the spread of resistance. Interventions to limit antibiotic use have the potential to reduce the spread of resistance, mainly by choosing an agent with a favorable profile in terms of its impact on patient's vulnerability and contagiousness. Methods to measure these impacts of antibiotics should be developed, standardized, and incorporated into drug development programs and approval packages.

Long-term efficacy of comprehensive multidisciplinary antibiotic stewardship programs centered on weekly prospective audit and feedback

OBJECTIVE

To evaluate the long-term effects of comprehensive antibiotic stewardship programs (ASPs) on antibiotic use, antimicrobial-resistant bacteria, and clinical outcomes.

DESIGN

Before-after study.

SETTING

National university hospital with 934 beds.

INTERVENTION

Implementation in March 2010 of a comprehensive ASPs including, among other strategies, weekly prospective audit and feedback with multidisciplinary collaboration.

METHODS

The primary outcome was the use of antipseudomonal antibiotics as measured by the monthly mean days of therapy per 1000 patient days each year. Secondary outcomes included overall antibiotic use and that of each antibiotic class, susceptibility of Pseudomonas aeruginosa, the proportion of patients isolated methicillin-resistant Staphylococcus aureus (MRSA) among all patients isolated S. aureus, the incidence of MRSA, and the 30-day mortality attributable to bacteremia.

RESULTS

The mean monthly use of antipseudomonal antibiotics significantly decreased in 2011 and after as compared with 2009. Susceptibility to levofloxacin was significantly increased from 2009 to 2016 (P = 0.01 for trend). Its susceptibility to other antibiotics remained over 84% and did not change significantly during the study period. The proportion of patients isolated MRSA and the incidence of MRSA decreased significantly from 2009 to 2016 (P < 0.001 and = 0.02 for trend, respectively). There were no significant changes in the 30-day mortality attributable to bacteremia during the study period (P = 0.57 for trend).

CONCLUSION

The comprehensive ASPs had long-term efficacy for reducing the use of the targeted broad-spectrum antibiotics, maintaining the antibiotic susceptibility of P. aeruginosa, and decreasing the prevalence of MRSA, without adversely affecting clinical outcome.

Impact of interventions by an antimicrobial stewardship program team on appropriate antimicrobial therapy in patients with bacteremic urinary tract infection

BACKGROUND

Inappropriate antimicrobial therapy often leads to poor outcomes. This study aimed to evaluate the impact of an antimicrobial stewardship program (ASP) team on appropriate therapy, in patients with bacteremic urinary tract infection (UTI).

PATIENTS AND METHODS

We retrospectively reviewed the interventions by the ASP team in 807 patients with bacteremic UTI. Interventions were divided into 3 groups: group A (conventional report), group B (conventional report and written alert on the chart), and group C (conventional report and oral recommendation with/without written alert). The appropriateness of antimicrobial therapy was assessed at 2 time points, based on blood culture results.

RESULTS

The ASP team estimated that 166 and 576 patients received inappropriate antimicrobial therapy based on the results of Gram staining, and final report, respectively. Appropriate therapy after intervention was administered to 53.2% of group A, 63.5% of group B, and 89.3% of group C patients, respectively. Mortality was significantly lower in patients of de-escalation than in those with no antimicrobial changes, without prolonged hospital stay.

CONCLUSION

This study provides one plausible benchmark for appropriate antimicrobial therapy by ASP, while observer bias and survivor treatment selection bias exist, and further studies including evaluation for severity are needed.

Molecular epidemiological survey of bacteremia by multidrug resistant Pseudomonas aeruginosa: the relevance of intrinsic resistance mechanisms

The bacterial factors associated with bacteremia by multidrug-resistant and extensively drug-resistant P. aeruginosa, including overexpression of efflux pumps, AmpC overproduction, and loss/alteration of the OprD porin in isolates that are non-Metallo-β-Lactamase producing were analyzed in a retrospective study. Molecular analyses included strain typing by Pulsed Field Gel Electrophoresis and identification of key genes via qualitative and quantitative PCR-based assays. Previous use of carbapenems and tracheostomy was independently associated with the development of bacteremia by extensively drug-resistant and multidrug-resistant strains of P. aeruginosa. A high consumption of antimicrobials was observed, and 75.0% of the isolates contained amplicons with the blaSPM-1 and blaVIM genes. Of the 47 non-Metallo-β-Lactamase isolates, none had another type of carbapenemase. However, the isolates exhibited high rates of hyperproduction of AmpC, loss of the OprD porin (71.4%) and the presence of MexABOprM (57.1%) and MexXY (64.3%). This study suggests that in non-Metallo-β-Lactamase isolates, the association of intrinsic resistance mechanisms could contributes to the expression of multidrug-resistant/extensively drug-resistant phenotypes.

Management of intra-abdominal infections: recommendations by the WSES 2016 consensus conference

This paper reports on the consensus conference on the management of intra-abdominal infections (IAIs) which was held on July 23, 2016, in Dublin, Ireland, as a part of the annual World Society of Emergency Surgery (WSES) meeting. This document covers all aspects of the management of IAIs. The Grading of Recommendations Assessment, Development and Evaluation recommendation is used, and this document represents the executive summary of the consensus conference findings.

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.

Correlation between antimicrobial consumption and antimicrobial resistance of Pseudomonas aeruginosa in a hospital setting: a 10-year study

WHAT IS KNOWN AND OBJECTIVE

Antimicrobial resistance is one of the greatest threats to human health. One of the most important factors leading to the emergence of resistant bacteria is overuse of antibiotics. The purpose of this study was to investigate the correlation between antimicrobial usage and bacterial resistance of Pseudomonas aeruginosa (P. aeruginosa) over a 10-year period in the Clinical Center Niš, one of the biggest tertiary care hospitals in Serbia. We focused on possible relationships between the consumption of carbapenems and beta-lactam antibiotics and the rates of resistance of P. aeruginosa to carbapenems.

METHODS

We recorded utilization of antibiotics expressed as defined daily doses per 100 bed days (DBD). Bacterial resistance was reported as the percentage of resistant isolates (percentage of all resistant and intermediate resistant strains) among all tested isolates.

RESULTS AND DISCUSSION

A significant increasing trend in resistance was seen in imipenem (P < 0·05, Spearman ρ = 0·758) and meropenem (P < 0·05, ρ = 0·745). We found a significant correlation between aminoglycoside consumption and resistance to amikacin (P < 0·01, Pearson r = 0·837) and gentamicin (P < 0·01, Pearson r = 0·827). The correlation between the consumption of carbapenems and resistance to imipenem in P. aeruginosa shows significance (P < 0·01, Pearson r = 0·795), whereas resistance to meropenem showed a trend towards significance (P > 0·05, Pearson r = 0·607). We found a very good correlation between the use of all beta-lactam and P. aeruginosa resistance to carbapenems (P < 0·01, Pearson r = 0·847 for imipenem and P < 0·05, Pearson r = 0·668 for meropenem).

WHAT IS NEW AND CONCLUSION

Our data demonstrated a significant increase in antimicrobial resistance to carbapenems, significant correlations between the consumption of antibiotics, especially carbapenems and beta-lactams, and rates of antimicrobial resistance of P. aeruginosa to imipenem and meropenem.

Microbiological findings in burn patients treated in a general versus a designated intensive care unit: Effect on length of stay

BACKGROUND

Infection is one of the most common causes of mortality and morbidity in burn patients. The incidence and frequency of microbiological micro-organisms are known to vary across different models of intensive care units. To date, no study has attempted to describe the different findings in burn patients treated in an open, general intensive care unit (GICU) versus a dedicated burns intensive care unit (BICU). Only limited data is available on the effect of these microbiological micro-organisms on patients' length of stay.

AIM

To characterize and compare the microbiological flora and antibiotic resistance patterns encountered in two different models of burn intensive care and to determine the effect of specific microbiological types on length of intensive care unit (ICU) and overall stay.

METHODS

A retrospective case-control study of 209 burn patients treated in two highly specialized, Western burn referral centres between September 2009 and March 2014.

RESULTS

9710 culture results were analysed, of which 2590 (26.7%) yielded positive results (1537 in the GICU and 1050 in the BICU). Gram-positive cultures were more frequently found in the GICU, whereas Gram-negative and yeast cultures were more prevalent in the BICU. The most frequently encountered micro-organisms in both units were similar and included Staphylococcus aureus, Pseudomonas aeruginosa, coagulase-negative staphylococci (CoNS) and Candida albicans. Significantly more resistant bacteria were detected in the BICU. Testing positive across all types of microbiological isolates, as well as for both Gram-positive and -negative bacteria significantly prolonged patient length of stay. This effect was even more pronounced if the micro-organisms were resistant to antimicrobial therapy.

CONCLUSION

There are notable differences in the microbiological isolate and antibiotic resistance patterns between burn patients treated in a GICU compared to a designated BICU. In both units, testing positive for resistant microbiological micro-organisms is significantly associated with longer hospital stay.

Antimicrobial Consumption Data From Pharmacy and Nursing Records: How Good Are They?

Objective:

To determine whether randomly selected intravenous (IV) antimicrobial doses dispensed from an inpatient pharmacy were administered.

Design:

This was a prospective, cross-sectional study in which dose administration was confirmed by direct observation and by assessment of the medication administration record (MAR). A retrospective analysis of the return rate of unused IV antimicrobial doses was performed subsequently.

Setting:

Medical and surgical intensive care units (ICUs) and non-ICUs of a 550-bed urban public teaching hospital.

Participants:

Hospitalized patients with an order in the pharmacy database for an IV antimicrobial during 9 non-consecutive weekdays in June 1999.

Results:

Of 397 doses, 221 (55.7%) assessed by bedside observation and 238 (59.9%) assessed by MAR review were classified as administered; 139 doses (35.0%) were dispensed but changes in the drug order or the patient's status prevented their administration. In the subsequent assessment, of 745 IV antimicrobial doses dispensed during 24 hours, 322 (43.2%) were returned to the pharmacy unused; 423 (56.8%) of the doses—consistent with our prior observations—were presumably administered.

Conclusions:

Because computerized pharmacy data may overestimate actual antimicrobial consumption, such data should be validated when used in studies of hospital antimicrobial use. Dispense-return analysis offers a simple validation method.

Seasonality of antibiotic prescriptions for outpatients and resistance genes in sewers and wastewater treatment plant outflow

To test the hypothesis of a seasonal relationship of antibiotic prescriptions for outpatients and the abundance of antibiotic resistance genes (ARGs) in the wastewater, we investigated the distribution of prescriptions and different ARGs in the Dresden sewer system and wastewater treatment plant during a two-year sampling campaign. Based on quantitative PCR (qPCR), our results show a clear seasonal pattern for relative ARGs abundances. The higher ARGs levels in autumn and winter coincide with the higher rates of overall antibiotic prescriptions. While no significant differences of relative abundances were observed before and after the wastewater treatment for most of the relative ARGs, the treatment clearly influenced the microbial community composition and abundance. This indicates that the ARGs are probably not part of the dominant bacterial taxa, which are mainly influenced by the wastewater treatment processes, or that plasmid carrying bacteria remain constant, while plasmid free bacteria decrease. An exception was vancomycin (vanA), showing higher relative abundance in treated wastewater. It is likely that a positive selection or community changes during wastewater treatment lead to an enrichment of vanA. Our results demonstrate that in a medium-term study the combination of qPCR and next generation sequencing corroborated by drug-related health data is a suitable approach to characterize seasonal changes of ARGs in wastewater and treated wastewater.

[Pharmacist interventions on antibiotic prescriptions in outpatient pediatric unit in a teaching hospital of Côte d'Ivoire]

OBJECTIVES

The objectives of our study were to analyse the prescriptions of antibiotics and assessing the relevance of pharmacist interventions (PI) in outpatient consultations in a pediatric unit of a Teaching Hospital of Abidjan, Côte d'Ivoire.

METHODS

We conducted a cross-sectional descriptive study from May to December 2013. The analysis of antibiotic prescriptions was documented. The tool of PI classification validated by the French Society of Clinical Pharmacy was used. The PI rating was made by prescribers. This rating evolved from PI0 to PI3 depending on the severity of the clinical impact of the problem and to the severity of clinical consequences avoided by the PI. The relevance was evaluated by the PI acceptance rate by physicians and clinical evaluation of their impact.

RESULTS

Our study included 150 patients with a mean age of 11.75 months and a sex ratio (M/F) of 2. The amoxicillin-clavulanic acid (27.2 %) and amoxicillin (22.3 %) were the most prescribed antibiotics. Sixty-three drug-related problems (DRPs) were detected on the antibiotic prescriptions. They were non-optimal drug administration plan (88.9 %) and underdose (11.1 %). The amoxicillin-clavulanic acid (61.9 %) and josamycin (17.4 %) were the most affected by these DRPs. PI were related to the precision of modes of drug administration (88.9 %) and dose adjustments (11.1 %). The prescribers accepted 93.7 % of PIs. All accepted PIs was rated PI1 (significant clinical impact).

CONCLUSIONS

PIs performed on antibiotic prescription were relevant with a high rate of acceptance and a significant clinical impact.

Antimicrobials: a global alliance for optimizing their rational use in intra-abdominal infections (AGORA)

Intra-abdominal infections (IAI) are an important cause of morbidity and are frequently associated with poor prognosis, particularly in high-risk patients. The cornerstones in the management of complicated IAIs are timely effective source control with appropriate antimicrobial therapy. Empiric antimicrobial therapy is important in the management of intra-abdominal infections and must be broad enough to cover all likely organisms because inappropriate initial antimicrobial therapy is associated with poor patient outcomes and the development of bacterial resistance. The overuse of antimicrobials is widely accepted as a major driver of some emerging infections (such as C. difficile), the selection of resistant pathogens in individual patients, and for the continued development of antimicrobial resistance globally. The growing emergence of multi-drug resistant organisms and the limited development of new agents available to counteract them have caused an impending crisis with alarming implications, especially with regards to Gram-negative bacteria. An international task force from 79 different countries has joined this project by sharing a document on the rational use of antimicrobials for patients with IAIs. The project has been termed AGORA (Antimicrobials: A Global Alliance for Optimizing their Rational Use in Intra-Abdominal Infections). The authors hope that AGORA, involving many of the world's leading experts, can actively raise awareness in health workers and can improve prescribing behavior in treating IAIs.

Gram-stain-based antimicrobial selection reduces cost and overuse compared with Japanese guidelines

BACKGROUND

The Gram stain has been used as an essential tool for antimicrobial stewardship in our hospital since the 1970s. The objective of this study was to clarify the difference in the targeted therapies selected based on the Gram stain and simulated empirical therapies based on the antimicrobial guidelines used in Japan.

METHODS

A referral-hospital-based prospective descriptive study was undertaken between May 2013 and April 2014 in Okinawa, Japan. All enrolled patients were adults who had been admitted to the Division of Infectious Diseases through the emergency room with suspected bacterial infection at one of three sites: respiratory system, urinary tract, or skin and soft tissues. The study outcomes were the types and effectiveness of the antibiotics initially selected, and their total costs.

RESULTS

Two hundred eight patients were enrolled in the study. The median age was 80 years. A significantly narrower spectrum of antibiotics was selected based on the Gram stain than was selected based on the Japanese guidelines. The treatments based on the Gram stain and on the guidelines were estimated to be equally highly effective. The total cost of antimicrobials after Gram-stain testing was less than half the cost after the guidelines were followed.

CONCLUSIONS

Compared with the Japanese guidelines, the Gram stain dramatically reduced the overuse of broad-spectrum antimicrobials without affecting the effectiveness of the treatment. Drug costs were reduced by half when the Gram stain was used. The Gram stain should be included in all antimicrobial stewardship programs.

More accurate measurement of vancomycin minimum inhibitory concentration indicates poor outcomes in meticillin-resistant Staphylococcus aureus bacteraemia

Meticillin-resistant Staphylococcus aureus (MRSA) is an important pathogen associated with community-acquired and nosocomial infections. The aim of this study was to validate the vancomycin (VAN) minimum inhibitory concentration (MIC) and administration of VAN that may affect the prognosis of patients with MRSA bacteraemia. In total, 140 clinical MRSA strains from blood cultures were collected from January 2009 to December 2013 at a university hospital in Tokyo (Japan). Patient background, their clinical situation and the susceptibility of isolates to anti-MRSA agents in all cases were reviewed, and factors contributing to 30-day mortality were analysed. Susceptibility to anti-MRSA agents was measured by a microdilution susceptibility testing method. The VAN MIC was further evaluated at 0.25 μg/mL intervals from 0.5 μg/mL to 2.0 μg/mL. Multiple logistic regression analysis revealed a 4-fold increase in mortality of patients with a VAN MIC ≥1.5 μg/mL [odds ratio (OR)=3.952, 95% confidence interval (CI) 1.471-10.614; P=0.006]. A one-score increase in the Charlson co-morbidity index resulted in a 1.2-fold increase in the risk of death (OR=1.199, 95% CI 1.054-1.364; P=0.006). However, no significant difference was found in the ratio of the VAN 24-h area under the concentration-time curve to MIC between VAN MIC ≥1.5 μg/mL and <1.5 μg/mL. A significant increase in the MICs of teicoplanin and daptomycin was observed in strains with high VAN MICs. For patients with high VAN MICs, administration of these anti-MRSA antibiotics may have a poor outcome owing to cross-resistance.

Relationship between Antimicrobial Consumption and the Incidence of Antimicrobial Resistance in Escherichia coli and Klebsiella pneumoniae Isolates

INTRODUCTION

Gram negative organisms are one of the major causes of nosocomial diseases. Development of resistance to antibiotics by these organisms increases their risk in clinical treatment of patients. It also affects morbidity and mortality hence needs to be monitored and controlled.

AIM

The aim of the present study was to analyse the correlation between consumption of parenteral antibiotics and the rates of antimicrobial resistance among the Escherichia coli and Klebsiella pneumoniae isolates collected during Dec 2010 - Jun 2013 from JIPMER hospital.

MATERIALS AND METHODS

Consumption data of parenteral antibiotics in J01 category of Anatomical Therapeutic Chemical (ATC) in JIPMER was obtained and expressed in Defined Daily Doses (DDD) per 1000 inhabitants. Valid consumption and resistance data during the period Dec 2010 to Jun 2013 were obtained at 6 month intervals and were correlated to draw a relationship between antimicrobial consumption and its impact on drug resistance for Escherichia coli and Klebsiella pneumoniae.

RESULTS

Escherichia coli isolates showed high resistance for increased use of gentamycin and ciprofloxacin. Increase in antibiotic consumption increases the resistance for Escherichia coli except for amikacin. Among the Klebsiella isolates, meropenem and gentamycin showed high correlations followed by ceftazidime, amikacin, ceftriaxone and ciprofloxacin.

CONCLUSION

In summary, a statistically significant association was noticed between consumption of the studied antimicrobials and resistance of Escherichia coli isolates, except for amikacin and ceftazidime. In the case of Klebsiella pneumoniae, there was a statistically significant association between the resistance rates and consumption of gentamycin, ceftazidime and meropenem. Further, a linear relationship was noted between antimicrobial consumption and resistant isolates of Escherichia coli and Klebsiella pneumoniae, except for Escherichia coli resistance to amikacin.

Decreased Resistance of Pseudomonas aeruginosa with Restriction of Ciprofloxacin in a Large Teaching Hospital's Intensive Care and Intermediate Care Units

Objective.

To examine the effect of restricting ciprofloxacin on the resistance of nosocomial gram-negative bacilli, including Pseudomonas aeruginosa, to antipseudomonal carbapenems.

Design.

Interrupted time-series analysis.

Setting.

Tertiary care teaching hospital with 11 intensive care and intermediate care units with a total of 295 beds.

Patients.

All nosocomial isolates of P. aeruginosa.

Intervention.

Restriction of ciprofloxacin.

Results.

There was a significant decreasing trend observed in the percentage (P = .0351) and the rate (P = .0006) of isolates of P. aeruginosa that were resistant to antipseudomonal carbapenems following the restriction of ciprofloxacin. There was also a significant decreasing trend observed in the percentage (P = .0017) and the rate (P = .0001) of isolates of ciprofloxacin-resistant P. aeruginosa. The rate of cefepime-resistant P. aeruginosa isolates declined (P = .004 ) but the percentage of cefepime-resistant P. aeruginosa isolates did not change. There were no significant changes observed in the rate or the percentage of piperacillin-tazobactam-resistant P. aeruginosa isolates. There were no significant changes observed in the susceptibilities of nosocomial Enterobacteriaciae or Acinetobacter baumannii isolates that were resistant to carbapenems. Over the study period there was a significant increase in the use of carbapenems (P = .0134); the use of ciprofloxacin decreased significantly (P = .0027). There were no significant changes in the use of piperacillin-tazobactam or cefepime.

Conclusion.

Restriction of ciprofloxacin was associated with a decreased resistance of P. aeruginosa isolates to antipseudomonal carbapenems and ciprofloxacin in our hospital's intermediate care and intensive care units. There were no changes observed in the susceptibilities of nosocomial Enterobacteriaciae or A. baumannii to carbapenems, despite increased carbapenem use. Reducing ciprofloxacin use may be a means of controlling multidrug-resistant P. aeruginosa.

Trends and correlation of antibacterial usage and bacterial resistance: time series analysis for antibacterial stewardship in a Chinese teaching hospital (2009-2013)

The purpose of this investigation was to describe the effect of antibacterial stewardship and evaluate the trends and correlation of antibacterial resistance and usage from 2009 to 2013 in a tertiary-care teaching hospital in northwest China. Antibacterial usage was expressed as defined daily doses per 100 patients per day (DDDs/100 PDs). Hospital-wide population-level data and time series analysis were used to evaluate the trends and determine associations between antibacterial exposure and acquisition of resistance. Yearly consumption of overall antibacterials significantly decreased from 66.54 to 28.08 DDDs/100 PDs (β = -10.504, p < 0.01). The resistant rates of the five most frequently isolated species (including Escherichia coli, Acinetobacter baumannii, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae) significantly decreased or remained stable, and none of them showed a statistically significant upward trend. The medical quality indicators got better or remained stable. Autoregressive integrated moving average (ARIMA) models demonstrated that the monthly resistance rate of P. aeruginosa to imipenem was strongly correlated with antipseudomonal carbapenems usage (β = 34.94, p < 0.001), as did the correlation of P. aeruginosa to meropenem with antipseudomonal third-generation cephalosporins usage (β = 32.76, p < 0.01) and K. pneumoniae to amikacin with aminoglycosides usage (β = 22.01, p < 0.001). The decreased antibacterial use paralleled the improved bacterial resistance without deteriorating medical quality indicators during antimicrobial stewardship. It also suggests that optimum antibiotic use is necessary to alleviate the threat posed by resistant microorganisms at the hospital level.

Clinical features and risk factors for development of Bacillus bacteremia among adult patients with cancer: a case-control study

PURPOSE

Bacillus species have been frequently reported in recent decades as true pathogens among cancer patients. The purpose of this study was to evaluate the clinical features and risk factors of Bacillus bacteremia among adult patients with cancer.

METHODS

A case-control study was performed to identify the risk factors of Bacillus bacteremia among adult patients with cancer at a 1,950-bed tertiary care university hospital. Electronic medical records were reviewed for individuals who were diagnosed with Bacillus bacteremia during the period of January 1995 through December 2012. Each case was matched to two controls with cancer and non-Bacillus bacteremia. Logistic regression model was used to identify independent risk factors for Bacillus bacteremia development.

RESULTS

A total of 86 patients with Bacillus bacteremia were included and compared with 172 control patients. The presence of a central venous catheter and use of extended-spectrum cephalosporin within 1 month were identified to be independent risk factors for the development of Bacillus bacteremia. Hospital stays longer than 14 days, a history of hematopoietic stem cell transplantation, and prior use of glycopeptides had a negative association.

CONCLUSIONS

The presence of a central venous catheter and prior use of extended-spectrum cephalosporin within 1 month were independent risk factors for the development of Bacillus bacteremia in adult cancer patients.

The role of quorum sensing system in antimicrobial induced ampC expression in Pseudomonas aeruginosa biofilm

The aim of this study was to evaluate the effects of quorum sensing (QS) systems in Pseudomonas aeruginosa (P. aeruginosa) on the expression of ampC gene induced by antibiotics. An in vitro dynamic model of P. aeruginosa biofilms was established in a silicon tube in once-flowthrough system at 37 °C. Biofilm generation was identified by argentation. Biofilm morphology of standard P. aeruginosa strain (PAO-1) and QS systems deficient strains (PDO100, rhlI deficient strain; PAO-JP1, lasI deficient strain; and PAO-MW1, rhlI and lasI deficient strain) were observed by optical microscope. The expression of ampC in PAO1, PAO1 with QS inhibitor (furanone C-30) and the QS deficient strains before and after induced by antibiotics were quantified by real-time quantitative PCR. The biofilms of PAO-1 and PDO100 were much thicker and denser than that of PAO-JP1 and PAO-MW1. Being induced by antibiotics, the expression of ampC in PAO1 and PDO100 was significantly higher than that in PAO-MW1 and PAO-JP1. With the effect of furanone C-30, the expression of ampC in PAO1 induced by antibiotics was reduced in a dose-dependent manner. QS system, especially the las system, plays an important role in both biofilm formation and antimicrobials induced ampC expression and furanone C-30 is a potent inhibitor for P. aeruginosa QS system.

Reversibility of antibiotic resistance

Although theoretically attractive, the reversibility of resistance has proven difficult in practice, even though antibiotic resistance mechanisms induce a fitness cost to the bacterium. Associated resistance to other antibiotics and compensatory mutations seem to ameliorate the effect of antibiotic interventions in the community. In this paper the current understanding of the concepts of reversibility of antibiotic resistance and the interventions performed in hospitals and in the community are reviewed.

Trends of isolation of intrinsically resistant to colistin Enterobacteriaceae and association with colistin use in a tertiary hospital

The objective of this investigation was to evaluate the association between colistin consumption and the isolation of intrinsically resistant to colistin Enterobacteriaceae (IRCE) in a university hospital in Crete, Greece. The database of the microbiological laboratory was reviewed retrospectively during 2006-2010. All positive cultures for IRCE were retrieved. We assessed the total consumption of colistin in medical, surgical, and intensive care units (ICUs). A total of 1,304 single-patient IRCE isolates were recorded. Of these, 466 (35.7%) were hospital-acquired, while 838 (64.3%) were community-acquired. Proteus spp. accounted for 72% of them, Serratia spp. for 16.6%, Morganella morganii for 8.4%, and Providencia spp. for 3%. Urine (44.8%), pus (20.4%), and lower respiratory tract specimens (12.8%) accounted for the majority of specimens. IRCE isolated during the first half (2006 to 1st semester of 2008) and second half (2nd semester of 2008 to 2010) of the study period accounted for 5.8% and 7.4% of Gram-negative isolates, respectively (p < 0.001). Colistin consumption was not different in the two periods in the hospital, but in the ICU, it was higher in the second half of the study period (p = 0.013). Colistin consumption was associated with the isolation of hospital-acquired IRCE (p = 0.037); a trend was noted between colistin consumption and the isolation of IRCE in the ICU (p = 0.057). In this study, colistin consumption was associated with the isolation of hospital-acquired IRCE. The use of colistin increased in the ICU during the study period. Prudent use of colistin is essential for the prevention of nosocomial outbreaks due to resistant IRCE.

Emergence of carbapenem resistance due to the novel insertion sequence ISPa8 in Pseudomonas aeruginosa

Chronic lung infections due to the persistence of Pseudomonas aeruginosa in cystic fibrosis patients are typically associated with the emergence of antibiotic resistance. The purpose of this study was to investigate the mechanisms responsible for the emergence of carbapenem resistance when a clinical isolate of P. aeruginosa collected from a patient with cystic fibrosis was challenged with meropenem. Nine carbapenem-resistant mutants were selected with subinhibitory concentrations of meropenem from a clinical isolate of P. aeruginosa and characterized for carbapenem resistance. Increased carbapenem MICs were associated with the identification of the novel insertion sequence ISPa8 within oprD or its promoter region in all the mutants. The position of ISPa8 was different for each of the mutants evaluated. In addition, Southern blot analyses identified multiple copies of ISPa8 within the genomes of the mutants and their parent isolate. These data demonstrate that transposition of IS elements within the Pseudomonas genome can influence antibiotic susceptibility. Understanding the selective pressures associated with the emergence of antibiotic resistance is critical for the judicious use of antimicrobial chemotherapy and the successful treatment of bacterial infections.

Antibiotic stewardship ward rounds and a dedicated prescription chart reduce antibiotic consumption and pharmacy costs without affecting inpatient mortality or re-admission rates

Background

Antibiotic consumption is a major driver of bacterial resistance. To address the increasing burden of multi-drug resistant bacterial infections, antibiotic stewardship programmes are promoted worldwide to rationalize antibiotic prescribing and conserve remaining antibiotics. Few studies have been reported from developing countries and none from Africa that report on an intervention based approach with outcomes that include morbidity and mortality.

Methods

An antibiotic prescription chart and weekly antibiotic stewardship ward round was introduced into two medical wards of an academic teaching hospital in South Africa between January-December 2012. Electronic pharmacy records were used to collect the volume and cost of antibiotics used, the patient database was analysed to determine inpatient mortality and 30-day re-admission rates, and laboratory records to determine use of infection-related tests. Outcomes were compared to a control period, January-December 2011.

Results

During the intervention period, 475.8 defined daily doses were prescribed per 1000 inpatient days compared to 592.0 defined daily doses/1000 inpatient days during the control period. This represents a 19.6% decrease in volume with a cost reduction of 35% of the pharmacy’s antibiotic budget. There was a concomitant increase in laboratory tests driven by requests for procalcitonin. There was no difference in inpatient mortality or 30-day readmission rate during the control and intervention periods.

Conclusions

Introduction of antibiotic stewardship ward rounds and a dedicated prescription chart in a developing country setting can achieve reduction in antibiotic consumption without harm to patients. Increased laboratory costs should be anticipated when introducing an antibiotic stewardship program.

Susceptibility Patterns inPseudomonas aeruginosaCausing Nosocomial Infections

Nosocomial infection caused by Pseudomonas aeruginosa has not been reported previously in the Gaza Strip. This study aims to determine the distribution of antimicrobial drug resistance in P. aeruginosa causing nosocomial infections. One hundred thirty-one P. aeruginosa isolates were collected from various nosocomial infection clinical samples. The study was conducted between April and October 2003. The results of this study reveal that the most common resistance was to ampicillin, followed by cephalexin. The most effective antimicrobial agents were meropenem and amikacin, respectively. The highest resistance to ciprofloxacin was found among ICU and surgery sections. The data analysis shows that no remarkable difference was reported with respect to previous admission and prior antimicrobial treatment for most antibiotics. The results of this study emphasize the need for constant monitoring of antimicrobial effectiveness to correctly guide empiric therapy and local intervention programs in an attempt to reduce antimicrobial resistance.

Effect of a Policy for Restriction of Selected Classes of Antibiotics on Antimicrobial Drug Cost and Resistance

Based on the instructions of the National Organization of Pharmaceutical Agents (Greece) from July 1, 2003, quinolones, 3( rd )and 4(th )generation cephalosporins, carbapenems, monobactams, glycopeptides, oxazolidinones, and streptogramins were considered as "restricted" antibiotics that could be used only with the approval of an Infectious Disease specialist. We analyzed the effect of the policy on the consumption and cost of antibiotics as a group and of specific classes, adjusted for the patient load, as well as on the antimicrobial resistance of isolated bacteria. We analyzed 5 trimesters (2 prior and 3 after the implementation of the new policy). A 20% and 16% reduction in adjusted consumption [in daily defined doses (DDDs)] and cost, respectively, of the restricted antibiotics was accomplished during the first trimester after implementation of the new policy. However, this was accompanied by a 36% and 56% increase in adjusted consumption and cost, respectively, of unrestricted antibiotics. A logistic regression model that we performed showed that the new policy had an independent positive effect on the in vitro antimicrobial susceptibility of Pseudomonas aeruginosa (p=0.051) but not of Acinetobacter baumannii and Escherichia coli isolates. Our data suggest that there are considerable limitations to the programs aiming to reduce the consumption of restricted antibiotics through the approval of their use by specialists, at least in some settings.

Impact of a program combining pre-authorization requirement and post-prescription review of carbapenems: an interrupted time-series analysis

The objective of this study was to assess the impact on carbapenems use of a program combining pre-authorization requirement and systematic post-prescription review of carbapenems prescriptions. The program was implemented in a 1,230-bed teaching tertiary hospital. Monthly carbapenems consumption was analyzed using a controlled interrupted time-series method and compared to that of vancomycin before and after implementation of the intervention. Compared to the pre-intervention period (14 monthly points), a significant and sustained decrease of carbapenems consumption [1.66 defined daily doses (DDD)/1,000 patient-days; p = 0.048] was observed during the intervention period (12 monthly points), despite an increasing trend in incidence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) isolates (0.02/1,000 patient-days per month; p = 0.093). As expected, vancomycin consumption was unaffected by the intervention. A total of 337 prescriptions were reviewed in the intervention period; most were microbiologically documented (81.3%; ESBL-PE: 39.2%). Three of four (76.6%) carbapenems prescriptions were modified within a median [interquartile range] of 2 [1; 4] days, either after infectious disease physician (IDP) advice (48.4%) or by ward physicians (28.2%). Most changes included de-escalating (52.2%) or reducing the planned duration (22.2%), which resulted in a median duration of treatment of only 3 [2; 7] days. The median length of stay and mortality rate were not influenced by the intervention. This reasonably practicable antimicrobial stewardship program including controlled delivery and systematic reevaluation of carbapenems prescriptions was able to reduce their use in our hospital, despite a rising ESBL-PE incidence.

Antibiotic consumption and healthcare-associated infections caused by multidrug-resistant gram-negative bacilli at a large medical center in Taiwan from 2002 to 2009: implicating the importance of antibiotic stewardship

Background

Better depicting the relationship between antibiotic consumption and evolutionary healthcare-associated infections (HAIs) caused by multidrug-resistant Gram-negative bacilli (MDR-GNB) may help highlight the importance of antibiotic stewardship.

Methodology/Principal Findings

The correlations between antibiotic consumption and MDR-GNB HAIs at a 2,700-bed primary care and tertiary referral center in Taiwan between 2002 and 2009 were assessed. MDR-GNB HAI referred to a HAI caused by MDR-Enterobacteriaceae, MDR-Pseudomonas aeruginosa or MDR-Acinetobacter spp. Consumptions of individual antibiotics and MDR-GNB HAI series were first evaluated for trend over time. When a trend was significant, the presence or absence of associations between the selected clinically meaningful antibiotic resistance and antibiotic consumption was further explored using cross-correlation analyses. Significant major findings included (i) increased consumptions of extended-spectrum cephalosporins, carbapenems, aminopenicillins/β-lactamase inhibitors, piperacillin/tazobactam, and fluoroquinolones, (ii) decreased consumptions of non-extended-spectrum cephalosporins, natural penicillins, aminopenicillins, ureidopenicillin and aminoglycosides, and (iii) decreasing trend in the incidence of the overall HAIs, stable trends in GNB HAIs and MDR-GNB HAIs throughout the study period, and increasing trend in HAIs caused by carbapenem-resistant (CR) Acinetobacter spp. since 2006. HAIs due to CR-Acinetobacter spp. was found to positively correlate with the consumptions of carbapenems, extended-spectrum cephalosporins, aminopenicillins/β-lactamase inhibitors, piperacillin/tazobactam and fluoroquinolones, and negatively correlate with the consumptions of non-extended-spectrum cephalosporins, penicillins and aminoglycosides. No significant association was found between the increased use of piperacilllin/tazobactam and increasing HAIs due to CR-Acinetobacter spp.

Conclusions

The trend in overall HAIs decreased and trends in GNB HAIs and MDR-GNB HAIs remained stable over time suggesting that the infection control practice was effective during the study period, and the escalating HAIs due to CR- Acinetobacter spp. were driven by consumptions of broad-spectrum antibiotics other than piperacillin/tazobactam. Our data underscore the importance of antibiotic stewardship in the improvement of the trend of HAIs caused by Acinetobacter spp.

Impact of antibiotic use on carbapenem resistance in Pseudomonas aeruginosa: is there a role for antibiotic diversity?

In this study, we aimed to evaluate the relationship between the rates of resistance of Pseudomonas aeruginosa to carbapenems and the levels and diversity of antibiotic consumption. Data were retrospectively collected from 20 acute care hospitals across 3 regions of Switzerland between 2006 and 2010. The main outcome of the present study was the rate of resistance to carbapenems among P. aeruginosa. Putative predictors included the total antibiotic consumption and carbapenem consumption in defined daily doses per 100 bed days, the proportion of very broad-spectrum antibiotics used, and the Peterson index. The present study confirmed a correlation between carbapenem use and carbapenem resistance rates at the hospital and regional levels. The impact of diversifying the range of antibiotics used against P. aeruginosa resistance was suggested by (i) a positive correlation in multivariate analysis between the above-mentioned resistance and the proportion of consumed antibiotics having a very broad spectrum of activity (coefficient = 1.77; 95% confidence interval, 0.58 to 2.96; P < 0.01) and (ii) a negative correlation between the resistance and diversity of antibiotic use as measured by the Peterson homogeneity index (coefficient = -0.52; P < 0.05). We conclude that promoting heterogeneity plus parsimony in the use of antibiotics appears to be a valuable strategy for minimizing the spread of carbapenem resistance in P. aeruginosa in hospitals.