Predicting hospital rates of fluoroquinolone-resistant Pseudomonas aeruginosa from fluoroquinolone use in US hospitals and their surrounding communities

Appropriate Duration of Antimicrobial Treatment for Prosthetic Joint Infections: A Narrative Review

Prosthetic joint infections are considered difficult to treat they needing aggressive surgery and long antimicrobial treatments. However, the exact duration of these therapies has been established empirically. In the last years, several studies have explored the possibility of reducing the length of treatment in this setting, with conflicting results. In this narrative review, we critically appraise the published evidence, considering the different surgical approaches (implant retention [DAIR] and one-step and two-step exchange procedures) separately. In patients managed with DAIR, usually treated for at least 12 weeks, a large, randomized trial failed to show that 6 weeks were non-inferior. However, another randomized clinical trial supports the use of 8 weeks, as long as the surgical conditions are favorable and antibiotics with good antibiofilm activity can be administered. In patients managed with a two-step exchange procedure, usually treated during 6 weeks, a randomized clinical trial showed the efficacy of a 4-week course of antimicrobials. Also, the use of local antibiotics may allow the use of even shorter treatments. Finally, in the case of one-step exchange procedures, there is a trend towards reducing the length of therapy, and the largest randomized clinical trial supports the use of 6 weeks of therapy.

Pharmaceuticals and personal care products in Tunisian hospital wastewater: occurrence and environmental risk

Despite concerns about the potential risk associated with the environmental occurrence of pharmaceuticals and personal care products (PPCPs), few studies address the emissions of hospitals to aquatic compartments. We examined within a 3-month sampling period the occurrence and environmental risk of PPCPs in seven Tunisian hospital wastewaters. From personal care products, UV filters, main metabolites, and benzotriazoles were quantified, with benzophenone 3 (oxybenzone, BP3) and benzotriazole (BZT) the most frequently found (71%) at median concentrations in the range 2.43 ± 0.87 ngL-1-64.05 ± 6.82 ngL-1 for BP3 and 51.67 ± 1.67 ngL-1-254 ± 9.9 ngL-1 for BZT. High concentrations were also found for 4-hydroxybenzophenone (4HB) (221 ± 6.22 ngL-1), one of the main metabolites of BP3. The antibiotics ofloxacin and trimethoprim, the anti-inflammatory acetaminophen, the antiepileptic carbamazepine, and the stimulant caffeine were present in all the wastewaters. The highest median concentration corresponded to acetaminophen, with 1240 ± 94 mgL-1 in Tunis Hospital, followed by ofloxacin with 78850 ± 39 μgL-1 in Sousse Hospital. For ecotoxicity assessment, acute toxicity was observed for Daphnia magna and Vibrio fischeri. The toxicity data were used in a hazard quotient (HQ) approach to evaluate the risk posed by the target PPCPs to aquatic organisms. The calculated HQs revealed that marbofloxacin (234 for V. fischeri), enrofloxacin (121 for D. magna), and BZT (82.2 for D. magna and 83.7 for V. fischeri) posed the highest risk, concluding that potential risk exists toward aquatic microorganisms. This study constitutes the first monitoring of UV filters in Tunisian hospital effluents and provides occurrence and toxicity data of PPCPs for reference in further surveys in the country.

Correlation between antibiotic consumption and resistance of Pseudomonas aeruginosa in a teaching hospital implementing an antimicrobial stewardship program: A longitudinal observational study

BACKGROUND/PURPOSE

The rapid emergence of Pseudomonas aeruginosa resistance made selecting antibiotics more challenge. Antimicrobial stewardship programs (ASPs) are urging to implant to control the P. aeruginosa resistance. The purpose of this study is to evaluate the relationship between antimicrobial consumption and P. aeruginosa resistance, the impact of ASPs implemented during the 14-year study period.

METHODS

A total 14,852 P. aeruginosa isolates were included in our study. The resistant rate and antimicrobial consumption were investigated every six months. Linear regression analysis was conducted to examine the trends in antibiotics consumption and antimicrobial resistance over time. The relationship between P. aeruginosa resistance and antimicrobial consumption were using Pearson correlation coefficient to analysis. The trend of resistance before and after ASPs implanted is evaluated by segment regression analysis.

RESULTS

P. aeruginosa resistance to ceftazidime, gentamicin, amikacin, ciprofloxacin and levofloxacin significantly decreased during the study period; piperacillin/tazobactam (PTZ), cefepime, imipenem/cilastatin and meropenem remained stable. The P. aeruginosa resistance to ciprofloxacin and levofloxacin increasing initial then decreased after strictly controlled the use of levofloxacin since 2007. As the first choice antibiotic to treat P. aeruginosa, the consumption and resistance to PTZ increase yearly and resistance became stable since extended-infusion therapy policy implant in 2009.

CONCLUSION

Our ASP intervention strategy, which included extended infusion of PTZ and restrict use of levofloxacin, may be used to control antimicrobial resistance of P. aeruginosa in medical practice.

Fluoroquinolone stewardship at a community health system: A decade in review

OBJECTIVE

To describe inpatient fluoroquinolone use and susceptibility data over a 10-year period after the implementation of an antimicrobial stewardship program (ASP) led by an infectious diseases pharmacist starting in 2011.

DESIGN

Retrospective surveillance study.

SETTING

Large community health system.

METHODS

Fluoroquinolone use was quantified by days of therapy (DOT) per 1,000 patient days (PD) and reported quarterly. Use data are reported for inpatients from 2016 to 2020. Levofloxacin susceptibility is reported for Pseudomonas aeruginosa and Escherichia coli for inpatients from 2011 to 2020 at a 4 adult-hospital health system.

RESULTS

Inpatient fluoroquinolone use decreased by 74% over a 5-year period, with an average decrease of 3.45 DOT per 1,000 PD per quarter (P < .001). Over a 10-year period, inpatient levofloxacin susceptibility increased by 57% for P. aeruginosa and by 15% for E. coli. P. aeruginosa susceptibility to levofloxacin increased by an average of 2.73% per year (P < .001) and had a strong negative correlation with fluoroquinolone use, r = -0.99 (P = .002). E. coli susceptibility to levofloxacin increased by an average of 1.33% per year (P < .001) and had a strong negative correlation with fluoroquinolone use, r = -0.95 (P = .015).

CONCLUSIONS

A substantial decrease in fluoroquinolone use and increase in P. aeruginosa and E. coli levofloxacin susceptibility was observed after implementation of an antimicrobial stewardship program. These results demonstrate the value of stewardship services and highlight the effectiveness of an infectious diseases pharmacist led antimicrobial stewardship program.

Intravenous antibiotic duration in the treatment of prosthetic joint infection: systematic review and meta-analysis

Introduction: Long antibiotic courses, including intravenous (IV) and oral administrations, are utilized in prosthetic joint infection (PJI) treatment. This meta-analysis examines the non-inferiority of short courses ( <  4 weeks) of IV antibiotics compared to long courses in treating PJI. Critical review of IV treatment is necessary due to the clinical, physical, and financial burden associated with it and its continued prolonged use in the US without much evidence to support the practice. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), databases were searched using predefined medical subject headings (MeSH). Results: The nine included studies reported 521 total hip arthroplasties (THAs) and 530 total knee arthroplasties (TKAs). There was no significant difference in the overall success rate in short- vs. long-duration IV antibiotics for PJI treatment: odds ratio (OR) of 1.65, 95 % confidence interval (CI) of 0.78-3.46, and p = 0 .18. However, due to the moderate to high heterogeneity (I 2 = 68  %, p   <  0.01) amongst studies, an adjusted success rate was calculated after the exclusion of two studies. This showed a statistically significant difference between both groups (OR of 2.45, 95 % CI of 1.21-4.96, p   <  0.001) favoring a short course of antibiotics and reflecting a more homogenous population (I 2 = 51  %, p = 0 .06). Conclusion: This study highlights the limited data available for evaluating IV antibiotic duration in the setting of PJI. We found that a shorter duration of IV antibiotics was non-inferior to a longer duration, with an improved OR of 2.45 for treatment success, likely shortening inpatient stay as well as lessening side effects and antimicrobial resistance with a lower cost to patients and overall healthcare.

Unraveling the Nature of Antibiotics: Is It a Cure or a New Hurdle to the Patient Treatment?

Antimicrobial resistance is an increasing problem worldwide that has been exacerbated by antibiotic misuse worldwide. Growing antibiotic resistance can be attributed to as well as leads to severe infections, complications, prolonged hospital admissions, and higher mortality. One of the most important goals of administering antimicrobials is to avoid establishing antibiotic resistance during therapy. This can be done by drastically lowering worldwide antimicrobial usage, both in present and future. While current management methods to legislate antimicrobials and educate the healthcare community on the challenges are beneficial, they do not solve the problem of attaining an overall reduction in antimicrobial usage in humans. Application of rapid microbiological diagnostics for identification and antimicrobial susceptibility testing, use of inflammation markers to guide initiation and duration of therapies, reduction of standard antibiotic course durations, individualization of antibiotic treatments, and dosing considering pharmacokinetics are all possible strategies to optimize antibiotic use in everyday clinical practice and reduce the risk of inducing bacterial resistance. Furthermore, to remove any impediments to proper prescribing, strategies to improve antibiotic prescribing and antibiotic stewardship programs should enable clinical reasoning and enhance the prescribing environment. In addition, the well-established association between antimicrobial usage and resistance should motivate efforts to develop antimicrobial treatment regimens that facilitate the evolution of resistance. This review discusses the role of antibiotics, their current application in human medicine, and how the resistance has evolved to the existing antibiotics based on the existing literature.

Antimicrobial Stewardship in the ICU

Increasing rates of infection and multidrug-resistant pathogens, along with a high use of antimicrobial therapy, make the intensive care unit (ICU) an ideal setting for implementing and supporting antimicrobial stewardship efforts. Overuse of antimicrobial agents is common in the ICU, as practitioners are challenged daily with achieving early, appropriate empiric antimicrobial therapy to improve patient outcomes. While early antimicrobial stewardship programs focused on the financial implications of antimicrobial overuse, current goals of stewardship programs align closely with those of critical care providers-to optimize patient outcomes, reduce development of resistance, and minimize adverse outcomes associated with antibiotic overuse and misuse such as acute kidney injury and Clostridioides difficile-associated disease. Significant opportunities exist in the ICU for critical care clinicians to support stewardship practices at the bedside, including thoughtful and restrained initiation of antimicrobial therapy, use of biomarkers in addition to rapid diagnostics, Staphylococcus aureus screening, and traditional microbiologic culture and susceptibilities to guide antibiotic de-escalation, and use of the shortest duration of therapy that is clinically appropriate. Integration of critical care practitioners into the initiatives of antimicrobial stewardship programs is key to their success. This review summarizes key components of antimicrobial stewardship programs and mechanisms for critical care practitioners to share the responsibility for antimicrobial stewardship.

Prevention and management of infections after exposure to ionising radiation

Ionising radiation impacts many organ systems, each of which comprises a level of immunity to infectious disease. Bone marrow toxicity after radiation results in a predisposition to leukopenia and subsequent susceptibility to bacterial, viral, and fungal infections. Radiation-induced damage to mucosal, integumentary, and solid organ structures disrupts additional lines of innate defense. Over the past three decades, much progress has been made in effective antimicrobial prophylaxis, resulting in decreased infectious complications and improved survival. Vaccination schedules following myeloablative radiation have become highly regimented and treatment of overt infectious complications is largely standardised. In this article, we discuss consequences, prevention, and management of infections following exposure to ionising radiation.

Ab initio molecular dynamics simulations and experimental speciation study of levofloxacin under different pH conditions

Levofloxacin is an extensively employed broad-spectrum antibiotic belonging to the fluoroquinolone class. Despite the extremely wide usage of levofloxacin for a plethora of diseases, the molecular characterization of this antibiotic appears quite poor in the literature. Moreover, the acid-base properties of levofloxacin - crucial for the design of efficient removal techniques from wastewaters - have never extensively been investigated so far. Here we report on a study on the behavior of levofloxacin under standard and diverse pH conditions in liquid water by synergistically employing static quantum-mechanical calculations along with experimental speciation studies. Furthermore, with the aim of characterizing the dynamics of the water solvation shells as well as the protonation and deprotonation mechanisms, here we present the unprecedented quantum-based simulation of levofloxacin in aqueous environments by means of state-of-the-art density-functional-theory-based molecular dynamics. This way, we prove the cooperative role played by the aqueous hydration shells in assisting the proton transfer events and, more importantly, the key place held by the nitrogen atom binding the methyl group of levofloxacin in accepting excess protons eventually present in water. Finally, we also quantify the energetic contribution associated with the presence of a H-bond internal to levofloxacin which, on the one hand, stabilizes the ground-state molecular structure of this antibiotic and, on the other, hinders the first deprotonation step of this fluoroquinolone. Among other things, the synergistic employment of quantum-based calculations and speciation experiments reported here paves the way toward the development of targeted removal approaches of drugs from wastewaters.

Secular trends of Blood stream infections in allogeneic hematopoietic cell transplant recipients 72 hours prior to death

INTRODUCTION

Blood stream infections (BSI) frequently cause morbidity and mortality in allogeneic (allo) hematopoietic cell transplant (HCT) recipients. Characteristics of causative organisms shortly before death have not been previously described. Early treatment with antimicrobial agents targeting the recent surge in multidrug-resistant (MDR) pathogens may lead to better outcomes.

METHODS

This is retrospective study including 529 allo HCT recipients who died between 2000 and 2013. All patients who had BSI that happened 72 hours before death were included. BSI and criteria for antimicrobial resistance were defined according to the Centers for Disease Control and Prevention and the National Healthcare Safety Network surveillance criteria.

RESULTS

Overall, 104 BSI were identified from 91 patients. Bacterial infections accounted for 87% of the infections which were comprised by 37% gram-negative organisms and 50% gram-positive bacteria. The most common species were Enterococcus (30%), Staphylococcus (16%), and Pseudomonas (16%). Most enterococci were vancomycin resistant (87%), 100% of staphylococci were resistant to methicillin, and 64% of Pseudomonas were MDR. Over time there was a significant increase in vancomycin-resistant enterococcal (P = .01) and gram-negative BSI (P = .01). Blood stream infections were either the primary or secondary cause of death in 53% of patients.

CONCLUSIONS

In allo HCT recipients, vancomycin-resistant enterococcal infections caused the majority of BSI 72 hours prior to death. Our findings provide information that may guide empiric antibiotic coverage in critically ill HCT recipients.

Association between the rate of fluoroquinolones-resistant gram-negative bacteria and antibiotic consumption from China based on 145 tertiary hospitals data in 2014

Background

The purpose of the study is to discuss the correlation between the resistance rate of gram negative bacteria to fluoroquinolones (FQ) and antibiotic consumption intensity of 145 China tertiary hospitals in 2014.

Methods

This retrospective study adopted national monitoring data from 2014. Each participating hospital required to report annual consumption of each antibiotic, and the resistance rate of gram negative bacteria to FQ. Then the correlation between antibiotic usage and fluoroquinolones –resistant (FQR) rate was consequently investigated.

Results

One hundred forty-five hospitals were included in the study, and the median antibiotic consumption intensity was 46.30 (23.93–115.39) defined daily dosages (DDDs) per 100 patient-days. Cephalosporins ranks first in the antibiotics consumption, followed by fluoroquinolones, penicillins, and carbapenems. Fluoroquinolones resistance rate varied from hospital to hospital. The correlation analysis showed significant relationship between the percentage of FQR Escherichia coli and the consumption of FQs (r = 0.308, p<0.01) and levofloxacin (r = 0.252, p<0.01). For FQR Klebsiella pneumoniae, not only FQs (r = 0.291, p<0.01) and levofloxacin (r = 0.260, p<0.01) use but also carbapenems (r = 0.242, p<0.01) and overall antibiotics (r = 0.247, p<0.01) use showed significant correlation. The resistant proportion of FQR Pseudomonas aeruginosa was observed to be correlated with the consumption of all antibiotics (r = 0.260, p<0.01), FQs (r = 0.319, p<0.01) and levofloxacin (r = 0.377, p<0.01). The percentage of levofloxacin-resistant Acinetobacter baumannii was significantly correlated with the consumption of all antibiotics (r = 0.282, p<0.01), third-generation cephalosporins excluding combinations with beta-lactamase inhibitors (r = 0.246, p<0.01), FQs (r = 0.254, p<0.01) and levofloxacin (r = 0.336, p<0.01). However, the correlation of the ciprofloxacin-resistant A. baumannii and the antibiotics consumption was not found.

Conclusions

A strong correlation was demonstrated between the antibiotic consumption and the rates of FQR gram-negative bacteria. As unreasonable antibiotics usage remains crucial in the proceeding of resistant bacteria selection, our study could greatly promote the avoidance of unnecessary antibiotic usage.

Risk factors for development of aminoglycoside resistance among gram-negative rods

PURPOSE

Development of scoring systems to predict the risk of aminoglycoside resistance and to guide therapy is described.

METHODS

Infections due to aminoglycoside-resistant gram-negative rods (AR-GNRs) are increasingly common and associated with adverse outcomes; selection of effective initial antibiotic therapy is necessary to reduce adverse consequences and shorten length of stay. To determine risk factors for AR-GNR recovery from culture, cases of GNR infection among patients admitted to 2 institutions in a major academic hospital system during the period 2011-2016 were retrospectively analyzed. Gentamicin and tobramycin resistance (GTR-GNR) and amikacin resistance (AmR-GNR) patterns were analyzed separately. A total of 26,154 GNR isolates from 12,516 patients were analyzed, 6,699 of which were GTR, and 2,467 of which were AmR.

RESULTS

In multivariate analysis, risk factors for GTR-GNR were presence of weight loss, admission from another medical or long-term care facility, a hemoglobin level of <11 g/dL, receipt of any carbapenem in the prior 30 days, and receipt of any fluoroquinolone in the prior 30 days (C statistic, 0.63). Risk factors for AmR-GNR were diagnosis of cystic fibrosis, male gender, admission from another medical or long-term care facility, ventilation at any point prior to culture during the index hospitalization, receipt of any carbapenem in the prior 30 days, and receipt of any anti-MRSA agent in the prior 30 days (C statistic, 0.74). Multinomial and ordinal models demonstrated that the risk factors for the 2 resistance patterns differed significantly.

CONCLUSION

A scoring system derived from the developed risk prediction models can be applied by providers to guide empirical antimicrobial therapy for treatment of GNR infections.

Impact of Chlorhexidine Bathing on Antimicrobial Utilization in Surgical Intensive Care Unit

BACKGROUND

This secondary analysis compared antimicrobial utilization among surgical intensive care unit patients randomized to every other day chlorhexidine bathing (chlorhexidine) versus daily soap and water bathing (soap-and-water) using data from the CHlorhexidine Gluconate BATHing trial.

MATERIALS AND METHODS

Antimicrobial utilization was quantified using defined daily dose (DDD)/100 patient-days and agent-days/100 patient-days for systemic antimicrobials. Antivirals (except oseltamivir), antiparasitics, and prophylaxis agents were excluded. The 2018 anatomic therapeutic chemical/DDD index was used to calculate DDD. Agent-days were calculated as the sum of calendar days where antimicrobials were administered. Patient-days were defined as time patients were at risk for health care-acquired infections plus up to 14 d. Primary analyses were conducted using linear regression adjusted for baseline Acute Physiology and Chronic Health Evaluation II scores.

RESULTS

Of 325 CHlorhexidine Gluconate BATHing trial patients, 312 (157 in soap-and-water and 155 in chlorhexidine) were included. The median (interquartile range) of total antimicrobial DDD/100 patient-days was 135.4 (75.2-231.8) for soap-and-water and 129.9 (49.2-215.3) for chlorhexidine. The median (interquartile range) of total antimicrobial agent-days/100 patient-days was 155.6 (83.3-243.2) for soap-and-water and 146.7 (66.7-217.4) for chlorhexidine. After adjusting for Acute Physiology and Chronic Health Evaluation II scores, chlorhexidine bathing was associated with a nonsignificant reduction in total antimicrobial DDD/100 patient-days (-3.9; 95% confidence interval, -33.9 to 26.1; P = 0.80) and total antimicrobial agent-days/100 patient-days (-10.3; 95% confidence interval, -34.7 to 14.1; P = 0.41).

CONCLUSIONS

Compared with daily soap and water bathing, every other day chlorhexidine bathing did not significantly reduce total antimicrobial utilization in surgical intensive care unit patients.

Risk Factors for Development of Carbapenem Resistance Among Gram-Negative Rods

Background

Infections due to carbapenem-resistant Gram-negative rods (CR-GNR) are increasing in frequency and result in high morbidity and mortality. Appropriate initial antibiotic therapy is necessary to reduce adverse consequences and shorten length of stay.

Methods

To determine risk factors for recovery on culture of CR-GNR, cases were retrospectively analyzed at a major academic hospital system from 2011 to 2016. Ertapenem resistance (ER-GNR) and antipseudomonal (nonertapenem) carbapenem resistance (ACR-GNR) patterns were analyzed separately. A total of 30951 GNR isolates from 12370 patients were analyzed, 563 of which were ER and 1307 of which were ACR.

Results

In multivariate analysis, risk factors for ER-GNR were renal disease, admission from another health care facility, ventilation at any point before culture during the index hospitalization, receipt of any carbapenem in the prior 30 days, and receipt of any anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) agent in the prior 30 days (c-statistic, 0.74). Risk factors for ACR-GNR were male sex, admission from another health care facility, ventilation at any point before culture during the index hospitalization, receipt of any carbapenem in the prior 30 days, and receipt of any anti-MRSA agent in the prior 30 days (c-statistic, 0.76).

Conclusions

A straightforward scoring system derived from these models can be applied by providers to guide empiric antimicrobial therapy; it outperformed use of a standard hospital antibiogram in predicting infections with ER-GNR and ACR-GNR.

Enantioselective fractionation of fluoroquinolones in the aqueous environment using chiral liquid chromatography coupled with tandem mass spectrometry

This paper aims to examine the multiresidue enantiomeric profiling of (fluoro)quinolones and their metabolites in solid and liquid environmental matrices using chiral HPLC-MS/MS method and a CHIRALCEL^® OZ-RH column. Simultaneous chiral separation was obtained for chiral ofloxacin and its main metabolites ofloxacin-N-oxide and desmethyl-ofloxacin; moxifloxacin; the prodrug prulifloxacin and its active compound ulifloxacin; flumequine; nadifloxacin and R-(+)-besifloxacin. Achiral antibiotics (ciprofloxacin, norfloxacin and nalidixic acid) were also included in the method to enable the analysis of all targeted quinolones within one analytical run. Satisfactory enantiomeric resolution (Rs ≥ 1) was obtained for five out of eight chiral drugs enabling quantitative analysis. The overall performance of the method was satisfactory with a method precision <20%, relative recoveries >70% for most of the analytes and method detection limits (MDL) at low ng L^-1 levels (0.1 < MDL (ng L^-1)< 6.4, 0.1 < MDL (ng L^-1)< 6.6 and 0.1 < MDL (ng L^-1)< 7.0 in influent, effluent and river waters for 83% compounds, 0.01 < MDL (ng g^-1)< 4.9 in solids for 91% compounds). Enantiomeric profiling from a week-long monitoring campaign in the UK showed that (±)-ofloxacin was found to be racemic in upstream waters but it was enriched with S-(-)-enantiomer in wastewater and in receiving waters. This could be due to the fact that ofloxacin can be used both as a racemate and as a S-(-)-enantiomer. Its consumption was further confirmed by the chiral signature of the investigated ofloxacin metabolites. As a result, alterations in the enantiomeric composition of antibiotics could influence not only their activity and toxicity in the environment, but also could induce changes in the microbial communities constantly exposed to them.

Risk Factors for Colistin Resistance among Gram-Negative Rods and Klebsiella pneumoniae Isolates

Infections due to colistin-resistant (Col^r) Gram-negative rods (GNRs) and colistin-resistant Klebsiella pneumoniae isolates in particular result in high associated mortality and poor treatment options. To determine the risk factors for recovery on culture of Col^r GNRs and Col^rK. pneumoniae, analyses were chosen to aid decisions at two separate time points: the first when only Gram stain results are available without any bacterial species information (corresponding to the Col^r GNR model) and the second when organism identification is performed but prior to reporting of antimicrobial susceptibility testing results (corresponding to the Col^rK. pneumoniae model). Cases were retrospectively analyzed at a major academic hospital system from 2011 to 2016. After excluding bacteria that were intrinsically resistant to colistin, a total of 28,512 GNR isolates (4,557 K. pneumoniae isolates) were analyzed, 128 of which were Col^r (i.e., MIC > 2 μg/ml), including 68 of which that were Col^rK. pneumoniae In multivariate analysis, risk factors for Col^r GNRs were neurologic disease, residence in a skilled nursing facility prior to admission, receipt of carbapenems in the last 90 days, prior infection with a carbapenem-resistant organism, and receipt of ventilatory support (c-statistic = 0.81). Risk factors for Col^rK. pneumoniae specifically were neurologic disease, residence in a skilled nursing facility prior to admission, receipt of carbapenems in the last 90 days, receipt of an anti-methicillin-resistant Staphylococcus aureus antimicrobial in the last 90 days, and prior infection with a carbapenem-resistant organism (c-statistic = 0.89). A scoring system derived from these models can be applied by providers to guide empirical antimicrobial therapy in patients with infections with suspected Col^r GNR and Col^rK. pneumoniae isolates.

Modeling the seasonality of Methicillin-resistant Staphylococcus aureus infections in hospitals with environmental contamination

A deterministic mathematical model with periodic antibiotic prescribing rate is constructed to study the seasonality of Methicillin-resistant Staphylococcus aureus (MRSA) infections taking antibiotic exposure and environmental contamination into consideration. The basic reproduction number R0 for the periodic model is calculated under the assumption that there are only uncolonized patients with antibiotic exposure at admission. Sensitivity analysis of R0 with respect to some essential parameters is performed. It is shown that the infection would go to extinction if the basic reproduction number is less than unity and would persist if it is greater than unity. Numerical simulations indicate that environmental cleaning is the most important intervention to control the infection, which emphasizes the effect of environmental contamination in MRSA infections. It is also important to highlight the importance of effective antimicrobial stewardship programmes, increase active screening at admission and subsequent isolation of positive cases, and treat patients quickly and efficiently.

Clinical characteristics of postoperative febrile urinary tract infections after ureteroscopic lithotripsy

Purpose

Ureteroscopic lithotripsy (URS) is gaining popularity for the management of ureteral stones and even renal stones, with high efficacy and minimal invasiveness. Although this procedure is known to be safe and to have a low complication rate, febrile urinary tract infection (UTI) after URS is not rare. Therefore, we aimed to analyze the risk factors and causative pathogens of febrile UTI after URS.

Materials and Methods

Between January 2013 and June 2015, 304 patients underwent URS for ureteral or renal stones. The rate of postoperative febrile UTI and the causative pathogens were verified, and the risk factors for postoperative febrile UTI were analyzed using logistic regression analysis.

Results

Of 304 patients, postoperative febrile UTI occurred in 43 patients (14.1%). Of them, pathogens were cultured in blood or urine in 19 patients (44.2%), and definite pathogens were not identified in 24 patients (55.8%). In patients with an identified pathogen, Pseudomonas aeruginosa had the highest incidence. Multivariate analysis showed that the operation time (p<0.001) was an independent risk factor for febrile UTI after URS. The cut-off value of operation time for increased risk of febrile UTI was 70 minutes.

Conclusions

Overall, febrile UTI after URS occurred in 14.1% of patients, and the operation time was an independent predictive factor for this complication. Considering that more than 83.7% of febrile UTIs after URS were not controlled with fluoroquinolones, it may be more appropriate to use higher-level antibiotics for treatment, even in cases with unidentified pathogens.

Antimicrobial Stewardship in Long-Term Care Facilities: Approaches to Creating an Antibiogram when Few Bacterial Isolates Are Cultured Annually

Antibiograms are important clinical tools to report and track antibiotic susceptibility and help guide empiric antimicrobial therapy. Antibiograms support compliance with antimicrobial stewardship (AMS) requirements from the Centers for Medicare and Medicaid Services and are in line with recommendations from the Centers for Disease Control and Prevention Core Elements of AMS for nursing homes/long-term care facilities (LTCFs). Unlike most acute-care settings, LTCFs are challenged in creating antibiograms because of the low number of bacterial isolates collected annually. Determining the best methodology for creating clinically useful antibiograms for LTCFs needs to be explored. Possible approaches include (1) extending the isolate data beyond 1 year, (2) combining isolate data from the same geographic region, (3) using a nearby acute-care facility's antibiogram as a proxy, or (4) collapsing isolate data. This article discusses the benefits and limitations of each approach.

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.

Presence of antibiotic residues in various environmental compartments of Shandong province in eastern China: Its potential for resistance development and ecological and human risk

OBJECTIVES

To investigate the occurrence of antibiotic residues in different types of environmental samples including water samples in rural Shandong province, China. Further, to characterize the potential ecological risk for development of antibiotic resistance in the environment, and the potential direct human health risk of exposure to antibiotics via drinking water and vegetables.

METHODS

Environmental samples (n = 214) (river water, waste water, drinking water, sediments, manure, soil and edible parts of vegetables) were collected in twelve villages in Shandong province in eastern China. High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to determine the concentration of antibiotic residues. The ratio of the measured environmental concentrations (MEC) to the predicted no-effect concentrations (PNEC) was used to evaluate the ecological risk (risk quotient, RQ) for development of antibiotic resistance. The potential risks to human health through exposure to antibiotics in drinking water were assessed by comparing measured environmental concentrations (MEC) and predicted no-effect concentration in drinking water (PNEC_DW), and in vegetables by comparing estimated daily intake (EDI) to ADI.

RESULTS

Sulfapyridine, sulfamethoxazole, ciprofloxacin, enrofloxacin, levofloxacin, norfloxacin, chloramphenicol, florfenicol, doxycycline, and metronidazole were detected at concentrations ranging between 0.3 and 3.9 ng/L in river water, 1.3 and 12.5 ng/L in waste water, 0.5 and 21.4 ng/L in drinking water, 0.31 and 1.21 μg/kg in river sediment, 0.82 and 1.91 μg/kg in pig manure, 0.1 and 11.68 μg/kg in outlet sediment, 0.5 and 2.5 μg/kg in soil, and 6.3 and 27.2 μg/kg in vegetables. The RQs for resistance development were >1 for enrofloxacin, levofloxacin, and ranged between 0.1 and 1 for ciprofloxacin. MECs/PNEC_DW ratios were <1 from exposure to antibiotics through drinking water for both adults and children. EDI/ADI ratios were <0.1 from exposure to antibiotics by vegetable consumption.

CONCLUSIONS

Antibiotic pollutants were ubiquitous in various environmental compartments of Shandong province of China. Risk estimates indicated a potential for the measured levels of enrofloxacin, levofloxacin and ciprofloxacin in waste water to pose an ecological risk for resistance selection, and further studies are needed to validate this finding. The investigated antibiotics did not appear to pose an appreciable direct human health risk from environmental exposure through drinking water or vegetables consumption. However, they might still pose a risk for resistance development.

Is fluoroquinolone monotherapy a useful alternative treatment for Pseudomonas aeruginosa bacteraemia?

PURPOSE

Pseudomonas aeruginosa bacteraemia is associated with high mortality, and most monotherapies are beta-lactam-based. We aimed to investigate clinical outcomes of definitive fluoroquinolone monotherapy versus beta-lactam monotherapy for P. aeruginosa bacteraemia.

METHODS

This retrospective study enrolled adult patients receiving definitive monotherapy with beta-lactam or fluoroquinolone between November 2013 and November 2014 at Taipei Veterans General Hospital. The independent risk factors for 28-day mortality were analyzed by logistic regression and propensity score-adjusted analysis.

RESULTS

Among the 105 patients enrolled, 78 patients received beta-lactams and 27 received fluoroquinolones (20 with ciprofloxacin and 7 with levofloxacin). Primary bacteraemia (39.0%) and urinary tract infections (37.1%) were the most common sources of bacteraemia. The 28-day mortality rate was 11.1% for those receiving fluoroquinolones and 32.1% for those receiving beta-lactams (P = 0.062). The 28-day mortality rate between the two groups stratified by APACHE II and Pitt bacteraemia scores showed no significant differences in each category. Propensity score-adjusted multivariate analysis revealed that definitive therapy with a fluoroquinolone was not associated with 28-day mortality (OR 0.42; 95% CI 0.08-2.23; P = 0.305).

CONCLUSIONS

Fluoroquinolone might be an alternative to beta-lactam as a definitive monotherapy for P. aeruginosa bacteraemia provided they are active in vitro. Our results could be a basis for further studies and provide a possible target for antibiotic stewardship interventions in P. aeruginosa bacteraemia.

Determination and health risk assessment of enrofloxacin, flumequine and sulfamethoxazole in imported Pangasius catfish products in Thailand

The goals of this study were to determine the levels of three antibiotics - enrofloxacin, flumequine and sulfamethoxazole - in Pangasius catfish products imported into Thailand and to assess the health risks from consumption. To extract these antibiotic residues, acetonitrile, methanol and a small amount of formic acid were used as solvents. Determination of the antibiotics after extraction steps was carried out by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technique. The results showed that 14 and 3 samples of Pangasius catfish products were contaminated with enrofloxacin and sulfamethoxazole, respectively. No flumequine residue was found. While the concentration levels of these antibiotics in most contaminated samples were lower than the European Union (EU) standard, one sample was found to contain sulfamethoxazole at 245.91 µg kg^-1, which was higher than the EU standard (100 µg kg^-1), indicating the likelihood that some contaminated freshwater fish products are widely distributed in Thai markets. Notably, the concentration levels of enrofloxacin in samples of Pangasius catfish with skin were higher than in non-skin products, suggesting that products with skin might retain more antibiotic residues than non-skin products. Although the hazard quotient showed that consuming imported Pangasius catfish products, based on the current consumption rate, will not adversely affect consumer health, antibiotic residues in Pangasius catfish products imported into Thailand should be continually monitored.

De-escalation versus continuation of empirical antimicrobial therapy in community-acquired pneumonia

OBJECTIVES

To compare mortality between de-escalation and continued empirical treatment in patients with community-acquired pneumonia.

METHODS

Using a nationwide administrative database, we identified adult patients with community-acquired pneumonia caused by Streptococcus pneumoniae, other streptococci, Haemophilus influenzae, Klebsiella pneumoniae, or Escherichia coli (n = 10,231) or of unknown etiology (n = 8247), discharged between July 2010 and March 2013. De-escalation was determined by the spectrum and number of antimicrobials at day 4. We used propensity score matching to obtain 489 pairs of de-escalation and continuation groups among pathogen-identified patients and 278 pairs among culture-negative patients to compare mortalities.

RESULTS

In the pathogen-identified patients, de-escalation was noninferior to continuation in 15-day mortality [5.3% in de-escalation versus 4.3% in continuation, a difference of 1.0% (95% confidence interval, -1.7% to 3.7%)] and in-hospital mortality [8.0% in de-escalation versus 8.8% in continuation, a difference of -0.8% (95% confidence interval, -4.3% to 2.7%)]. In the culture-negative cases, de-escalation was noninferior to continuation in terms of 15-day mortality but not in terms of in-hospital mortality.

CONCLUSIONS

Among patients with community-acquired pneumonia of specific etiology, de-escalation was noninferior to continuation of empirical treatment, suggesting that de-escalation is a safe strategy and supporting current recommendations. Safety of de-escalation in culture-negative cases is questionable.

Effects of various antimicrobial stewardship programs on antimicrobial usage and resistance among common gram-negative bacilli causing health care-associated infections: A multicenter comparison

BACKGROUND

The effects of various antimicrobial stewardship programs (ASPs) on both antibiotic consumption and resistance among different hospitals within the same insurance system have rarely been investigated.

METHODS

This 6-year retrospective study included three medical centers with similar facilities and infection control measures in Taiwan. These hospitals used different types of ASPs: one had a hospital-wide preauthorization requirement by infectious diseases physicians for all broad-spectrum antibiotics, covering all intensive care units; the second used the same program, but excluded all intensive care units; and the third used postprescription review only. The nonsusceptibility of unduplicated isolates of gram-negative bacilli causing health care-associated infections and consumption of broad-spectrum antibiotics were analyzed.

RESULTS

Overall, the usage of broad-spectrum antibiotics of all classes escalated significantly over time in all three hospitals, but consumption was lowest under the hospital-wide preauthorization program. Under this ASP, despite a 2-fold increase in the total broad-spectrum antibiotic consumption during study period, some declining trends of resistance were found, including ciprofloxacin-resistant Pseudomonas aeruginosa and Acinetobacter baumannii, and carbapenem-resistant P. aeruginosa. By contrast, the other two hospitals with preauthorization program excluding all intensive care units and postprescription review had similar high broad-spectrum antibiotic consumption, comparable growing trends of resistant strains in general, and the correlations of antibiotic consumption and resistance were basically positive. Carbapenem-resistant A. baumannii increased significantly over time in all three hospitals.

CONCLUSION

This interhospital comparison suggested that hospital-wide preauthorization program is the most effective to reduce key gram-negative bacilli resistance, with the exception of carbapenem-resistant A. baumannii.

Evaluation of regional antibiograms to monitor antimicrobial resistance in Hampton Roads, Virginia

We studied recent antibiograms (2010 to 2011) from 12 hospitals in the Hampton Roads area, Virginia, that refer patients to a tertiary-care facility affiliated with Eastern Virginia Medical School. The data was compiled into a regional antibiogram, and sensitivity rates of common isolates from the tertiary-care facility (central) were compared to those of referring hospitals grouped by locale. Staphylococcus aureus was the most common Gram- positive and E. coli the most common Gram- negative organism grown from clinical samples in the area. Overall 53% of S.aureus isolates were resistant to oxacillin. There was a broad scatter of MIC (minimum inhibitory concentration) for vancomycin within the susceptibility range, and MIC of 4 μg/mL was reported in 2012. Penicillin resistance was seen in 50% and erythromycin resistance in 45% of Streptococcus pneumoniae. Vancomycin resistance was seen in 75% of Enterococcus faecium and 2% of Enterococcus faecalis respectively. Acinetobacter baumannii was the most resistant Gram negative organism in the data compiled. Among the Escherichia coli, 26%, 44% and 52%were resistant to Trimethoprim/Sulfamethoxazole ( SXT) ampicillin- sulbactam and ampicillin respectively. We found significant differences in methodology, interpretation and antibiotic panels used by area laboratories. Based on these findings, we are now prospectively following resistance patterns in the tertiary-care facility, sharing data, and creating a consistent approach to antimicrobial susceptibility testing in the region.

Comparison of antibiotic prophylaxis with cotrimoxazole/colistin (COT/COL) versus ciprofloxacin (CIP) in patients with acute myeloid leukemia

PURPOSE

Recent meta-analyses showed that antibiotic prophylaxis in patients with neutropenia after chemotherapy reduced the incidence of fever and mortality rate. Fluoroquinolones appear to be most effective and well tolerated. Thus, in April 2008, we changed our antibiotic prophylaxis regimen from cotrimoxazole/colistin (COT/COL) to the fluoroquinolone ciprofloxacin (CIP) in patients with acute myeloid leukemia (AML). The aim of this retrospective study was to compare efficacy and development of bacterial resistance with two different prophylaxis regimens over a time period of more than 4 years.

METHODS

Induction chemotherapy courses given for AML during the antibiotic prophylaxis period with COT/COL (01/2006-04/2008) and CIP (04/2008-06/2010) were retrospectively analyzed with a standard questionnaire.

RESULTS

Eighty-five courses in the COT/COL group and 105 in the CIP group were analyzed. The incidence of fever was not significantly different (COT/COL 80 % vs CIP 77 %; p = 0.724). Also, the rate of microbiologically documented infections was nearly the same (29 vs 26 %; p = 0.625). In addition, there was no significant difference in the incidence of clinically documented infections (11 vs 19 %; p = 0.155) or in the rates of detected gram-positive and gram-negative bacteria. Of note, there was no increase in resistance rates or cases with Clostridium difficile-associated diarrhea in the CIP group.

CONCLUSION

The antibiotic prophylaxis with CIP compared to COT/COL in AML was similarly effective with no increase in bacterial resistance. COT/COL may have the advantages of providing additional prophylaxis against Pneumocystis jirovecii pneumonia and leaving fluoroquinolones as an additional option for treatment of febrile neutropenia.

Inappropriate use of antibiotics in hospitals: the complex relationship between antibiotic use and antimicrobial resistance

Hospitals are considered an excellent compartment for the selection of resistant and multi-drug resistant (MDR) bacteria. The overuse and misuse of antimicrobial agents are considered key points fuelling this situation. Antimicrobial stewardship programs have been designed for better use of these compounds to prevent the emergence of resistant microorganisms and to diminish the upward trend in resistance. Nevertheless, the relationship between antibiotic use and antimicrobial resistance is complex, and the desired objectives are difficult to reach. Various factors affecting this relationship have been advocated including, among others, antibiotic exposure and mutant selection windows, antimicrobial pharmacodynamics, the nature of the resistance (natural or acquired, including mutational and that associated with horizontal gene transfer) and the definition of resistance. Moreover, antimicrobial policies to promote better use of these drugs should be implemented not only in the hospital setting coupled with infection control programs, but also in the community, which should also include animal and environmental compartments. Within hospitals, the restriction of antimicrobials, cycling and mixing strategies and the use of combination therapies have been used to avoid resistance. Nevertheless, the results have not always been favorable and resistant bacteria have persisted despite the theoretical benefits of these strategies. Mathematical models as well as microbiological knowledge can explain this failure, which is mainly related to the current scenario involving MDR bacteria and overcoming the fitness associated with resistance. New antimicrobials, rapid diagnostic and antimicrobial susceptibility testing and biomarkers will be useful for future antimicrobial stewardship interventions.

Inpatient antibiotic consumption in a regional secondary hospital in New Zealand

BACKGROUND

Reporting of antibiotic consumption in hospitals is a crucial component of antibiotic stewardship, but data from Australasian secondary hospitals are scarce. The hypothesis of this audit is that antibiotic consumption in secondary hospitals would be lower than in tertiary centres.

AIMS

The study aims to present the first published audit of antibiotic consumption from a secondary hospital in New Zealand compared with two tertiary centres.

METHODS

Hospital population-level data were retrospectively accessed to identify all systemic antibiotics dispensed to adult inpatients at Taranaki District Health Board during 2011. Consumption was calculated in defined daily doses per 100 inpatient-days and per 100 admissions, stratified by drug class. Comparison was against published data from two tertiary centres.

RESULTS

Total consumption was lower, but that of high-risk antibiotic classes was higher than both tertiary centres. The relative consumption of lincosamides was 4.0 and 2.6 times higher than the two tertiary centres, with an associated 14% incidence of Clostridium difficile associated diarrhoea within 3 months.

CONCLUSION

Our secondary hospital appears to consume the wrong types of antibiotic rather than too much. Data from all Australasian hospitals, stratified by clinical service area and hospital level, are required for clinically relevant benchmarking.

Treatment ofPseudomonas aeruginosainfection in critically ill patients

Critically ill patients are on the increase in the present clinical setting. Aging of our population and increasingly aggressive medical and therapeutic interventions, including implanted foreign bodies, organ transplantation and advances in the chemotherapy of malignant diseases, have created a cohort of particularly vulnerable patients. Pseudomonas aeruginosa is one of the leading gram-negative organisms associated with nosocomial infections. This organism is frequently feared because it causes severe hospital-acquired infections, especially in immunocompromised hosts, and is often antibiotic resistant, complicating the choice of therapy. The epidemiology, microbiology, mechanisms of resistance and currently available and future treatment options for the most relevant infections caused by P. aeruginosa are reviewed.

Canine superficial bacterial folliculitis: current understanding of its etiology, diagnosis and treatment

Superficial bacterial folliculitis (SBF) is more common in the dog than other mammalian species. Until recently, a successful outcome in cases of canine SBF was possible by administering a potentiated amoxicillin, a first generation cephalosporin or a potentiated sulfonamide. Unfortunately, this predictable susceptibility has changed, because methicillin resistant Staphylococcus pseudintermedius (MRSP) and Staphylococcus aureus (MRSA) are becoming more prevalent in canine SBF cases. The increasing frequency of multidrug resistance complicates the selection of antimicrobial therapy. Antimicrobial agents that were once rarely used in cases of canine SBF, such as amikacin, rifampicin and chloramphenicol, are becoming the drugs of choice, based on bacterial culture and susceptibility testing. Furthermore, changes in antimicrobial susceptibility have helped to re-emphasize the importance of a multimodal approach to treatment of the disease, including topical therapy. Due to the increasing frequency of identification of highly resistant Staphylococcus spp., topical antimicrobial therapy, including the use of diluted sodium hypochlorite (bleach), is becoming necessary to successfully treat some cases of canine SBF. Other important antiseptics that can be used include chlorhexidine, benzoyl peroxide, ethyl lactate, triclosan and boric acid/acetic acid. This review discusses the diagnostic and therapeutic management of canine SBF, with a special emphasis on treating methicillin resistant staphylococcal infections.

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

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

The changing epidemiology of methicillin-resistant Staphylococcus aureus in the United States: a national observational study

Methicillin-resistant Staphylococcus aureus (MRSA) can cause major illness and death and impose serious economic costs on patients and hospitals. Community-associated MRSA (CA-MRSA) is a growing problem in US hospitals, which are already dealing with high levels of hospital-associated MRSA (HA-MRSA), but little is known about how patient age and seasonal differences in the incidence of these 2 forms of MRSA affect the epidemic. By using national data on hospitalizations and antibiotic resistance, we estimated the magnitude and trends in annual S. aureus and MRSA hospitalization rates from 2005-2009 by patient age, infection type, and resistance phenotype (CA-MRSA vs. HA-MRSA). Although no statistically significant increase in the hospitalization rate was seen over the study period, the total number of infections increased. In 2009, there were an estimated 463,017 (95% confidence interval: 441,595, 484,439) MRSA-related hospitalizations at a rate of 11.74 (95% confidence interval: 11.20, 12.28) per 1,000 hospitalizations. We observed significant differences in infection type by age, with HA-MRSA-related hospitalizations being more common in older individuals. We also noted significant seasonality in incidence, particularly in children, with CA-MRSA peaking in the late summer and HA-MRSA peaking in the winter, which may be caused by seasonal shifts in antibiotic prescribing patterns.

Variation in hospital antibiotic prescribing practices for children with acute lymphoblastic leukemia

Antibiotic variation among pediatric oncology patients has not been well-described. Identification of significant variability in antibiotic use within this population would warrant evaluation of its clinical impact. We conducted a retrospective cohort study of newly diagnosed patients with pediatric acute lymophoblastic leukemia (ALL) hospitalized from 1999 to 2009 in 39 freestanding US children's hospitals within the Pediatric Health Information System. Medication use data were obtained for the first 30 days from each patient's index ALL admission date. Antibiotic exposure rates were reported as antibiotic days/1000 hospital days. Unadjusted composite broad-spectrum antibiotic exposure rates varied from 577 to 1628 antibiotic days/1000 hospital days. This wide range of antibiotic exposure was unaffected by adjustment for age, gender, race and days of severe illness (adjusted range: 532-1635 days of antibiotic therapy/1000 hospital days). Antibiotic use for children with newly diagnosed ALL varies widely across children's hospitals and is not explained by demographics or illness severity.

Seasonality and temporal correlation between community antibiotic use and resistance in the United States

BACKGROUND

Therapeutic antibiotic use in humans is a significant driver of antibiotic resistance. The seasonal effect of antibiotic use on antibiotic resistance has been poorly quantified because of lack of large-scale, spatially disaggregated time-series data on antibiotic use and resistance.

METHODS

We used time-series analysis (Box-Jenkins) on US antibiotic usage from IMS Health and on antibiotic resistance from The Surveillance Network from 1999-2007 to estimate the effect of aminopenicillin, fluoroquinolone, trimethoprim/sulfamethoxazole, and tetracycline usage on resistance of Escherichia coli to drugs within these classes. We also quantified the effect of fluoroquinolone and macrolide/lincosamide usage on resistance of methicillin-resistant Staphylococcus aureus (MRSA) to ciprofloxacin and clindamycin (which has a similar mode of action to macrolides), respectively.

RESULTS

Prevalence of resistant Escherichia coli was significantly correlated with lagged (by 1 month) antibiotic prescriptions for aminopenicillins (0.22, P = .03) and fluoroquinolones (0.24, P = .02), which are highly prescribed, but was uncorrelated to antibiotic classes with lower prescription levels. Fluoroquinolone prescriptions were also significantly correlated with a 1-month lag with the prevalence of ciprofloxacin-resistant MRSA (0.23, P = .03).

CONCLUSIONS

Large-scale usage of antibiotics can generate seasonal patterns of resistance that fluctuate on a short time scale with changes in antibiotic retail sales, suggesting that use of antibiotics in the winter could have a significant effect on resistance. In addition, the strong correlation between community use of antibiotics and resistance isolated in the hospital indicates that restrictions imposed at the hospital level are unlikely to be effective unless coordinated with campaigns to reduce unnecessary antibiotic use at the community level.

Occurrence and fate of quinolone and fluoroquinolone antibiotics in a municipal sewage treatment plant

This study developed a method for analysis of nineteen quinolone and fluoroquinolone antibiotics (FQs) in sludge samples, and investigated the occurrence and fate of the FQs in a municipal sewage treatment plant (STP) with anaerobic, anoxic, and aerobic treatment processes. Eleven compounds, including pipemidic acid, fleroxacin, ofloxacin, norfloxacin, ciprofloxacin, enrofloxacin, lomefloxacin, sparfloxacin, gatifloxacin, moxifloxacin, and sarafloxacin (only in sludge), were detected in the STP. The predominance of ofloxacin and norfloxacin, followed by lomefloxacin, ciprofloxacin, gatifloxacin, and moxifloxacin, were found in wastewater, suspended solids, and sludge. The total concentrations of FQs were 2573 ± 241 ng/L, 1013 ± 218 ng/L, and 18.4 ± 0.9 mg/kg in raw sewage, secondary effluent, and sludge, respectively. Extremely low mass change percentages were observed for FQs in anaerobic, anoxic, and aerobic treatment units, suggesting biodegradation to be of minor importance in the removal of FQs in STPs. 50-87% of the initial FQs loadings (except for pipemidic acid (36%)) were ultimately found in the dewatered sludge. Mean removal efficiencies of FQs in the STP were 56-75%, except for new generation drugs such as moxifloxacin (40 ± 5%) and gatifloxacin (43 ± 13%). A significant positive correlation was found between removal efficiencies and K(d) of FQs. The major factor in the removal of FQs in the STP was sorption to sludge, which was not governed by hydrophobic interactions. The long-term cycling and persistence of FQs in the STP has made activated sludge as a huge reservoir of FQ antibiotics.

Reduction of fluoroquinolone use is associated with a decrease in methicillin-resistant Staphylococcus aureus and fluoroquinolone-resistant Pseudomonas aeruginosa isolation rates: a 10 year study

OBJECTIVES

High rates of methicillin-resistant Staphylococcus aureus (MRSA) and fluoroquinolone-resistant Pseudomonas aeruginosa may be related, in part, to the overuse of fluoroquinolones. The objective was to analyse and correlate long-term surveillance data on MRSA and fluoroquinolone-resistant P. aeruginosa rates and antibiotic consumption after implementation of an institution-wide programme to reduce fluoroquinolone use.

METHODS

An interrupted time series/quasi-experimental study of monthly fluoroquinolone use and MRSA and fluoroquinolone-resistant P. aeruginosa isolation rates was carried out in a tertiary hospital during three periods: pre-intervention (January 2000-August 2005), intervention (September 2005-March 2006), and post-intervention (March 2006-March 2010). The effect of the intervention on the consumption of fluoroquinolones and bacterial resistance was assessed using segmented regression analyses.

RESULTS

Mean monthly fluoroquinolone consumption dropped by 29.1 defined daily doses per 1000 patient-days (DDD/1000 PD) (95% CI 13.1-45.9; P = 0.0005) from a mean of 148.2 to 119.1 DDD/1000 PD during the intervention period. A sustained and significant decrease in fluoroquinolone consumption of -0.95 DDD/1000 PD/month was also observed during the post-intervention period (P = 0.0002). During the post-intervention period the rate of fluoroquinolone-resistant P. aeruginosa continuously decreased, from a mean of 42% to 26%, with a constant relative change rate of -13%/year (95% CI -19 to -5, P = 0.001). A decrease in the MRSA rate was observed during the intervention period, from a mean resistance rate of 27% to 21% (P < 0.0001).

CONCLUSIONS

We showed the sustained impact of a fluoroquinolone control programme on the reduction of fluoroquinolone use with a significant decrease in fluoroquinolone-resistant P. aeruginosa and MRSA rates over 4 years.

Infections, bacterial resistance, and antimicrobial stewardship: the emerging role of hospitalists

The care of patients with serious infections both within and outside healthcare settings is increasingly complicated by the high prevalence of resistant or multidrug-resistant (MDR) pathogens. Moreover, infections caused by MDR versus susceptible bacteria or other pathogens are associated with significantly higher mortality, length of hospital stay, and healthcare costs. Antimicrobial misuse or overuse is the primary driver for development of antimicrobial resistance, suggesting that better use of antimicrobials will translate into improved patient outcomes, more efficient use of hospital resources, and lowered healthcare costs. Antimicrobial stewardship refers to the various practices and procedures utilized to optimize antimicrobial use. The primary goal of antimicrobial stewardship is to improve patient outcomes and lower antimicrobial resistance and other unintended consequences of antimicrobial therapy. Secondary goals are to reduce length of hospital stays and healthcare-related costs. Hospitalists are increasingly involved in the care of hospitalized patients throughout the United States. Expertise in managing conditions requiring hospitalization, and experience in quality improvement across a wide range of clinical conditions, make hospitalists well positioned to participate in the development and implementation of hospital-based antimicrobial stewardship programs designed to improve patient outcomes, reduce antimicrobial resistance, and provide more efficient and lower-cost hospital care.

Incidence of fluoroquinolone-resistant and extended-spectrum β-lactamase-producing Escherichia coli at a comprehensive cancer center in the United States

BACKGROUND

Quinolones are used extensively for prophylaxis in high-risk cancer patients; however, increasing quinolone resistance is being reported. Extended-spectrum β-lactamase (ESBL)-producing E. coli may be associated with increased morbidity and mortality particularly in neutropenic cancer patients.

METHODS

We conducted a retrospective study of consecutive E. coli isolates from January 2009 to August 2009 at our institution. Data on antimicrobial susceptibility of E. coli isolates to commonly used antimicrobial agents and the frequency of ESBL production and fluoroquinolone resistance were gathered based on CLSI guidelines.

RESULTS

There were 443 isolates of E. coli recovered. The majority were from urine cultures (308 isolates, 69.5%). Forty-one (9.2%) isolates were ESBL producing. Nine (18.3%) of the 49 isolates recovered from blood stream infections were ESBL producing. Quinolone resistance was present in 204 isolates (46%). Carbapenems and aminoglycosides retained excellent activity. E. coli resistance to quinolones increased from 13 to 46% in a period of 13 years (p = 0.001).

CONCLUSION

The incidence of resistance to quinolones at our center may be increasing as a consequence of widespread use of quinolones as prophylaxis for neutropenic patients. ESBL-producing E. coli are frequent at our center and are associated with blood stream infections.

Emergence and spread of antibiotic resistance following exposure to antibiotics

Within a susceptible wild-type population, a small fraction of cells, even <10(-9) , is not affected when challenged by an antimicrobial agent. This subpopulation has mutations that impede antimicrobial action, allowing their selection during clinical treatment. Emergence of resistance occurs in the frame of a selective compartment termed a mutant selection window (MSW). The lower margin corresponds to the minimum inhibitory concentration of the susceptible cells, whereas the upper boundary, named the mutant prevention concentration (MPC), restricts the growth of the entire population, including that of the resistant mutants. By combining pharmacokinetic/pharmacodynamic concepts and an MPC strategy, the selection of resistant mutants can be limited. Early treatment avoiding an increase of the inoculum size as well as a regimen restricting the time within the MSW can reduce the probability of emergence of the resistant mutants. Physiological and, possibly, genetic adaptation in biofilms and a high proportion of mutator clones that may arise during chronic infections influence the emergence of resistant mutants. Moreover, a resistant population can emerge in a specific selective compartment after acquiring a resistance trait by horizontal gene transfer, but this may also be avoided to some extent when the MPC is reached. Known linkage between antimicrobial use and resistance should encourage actions for the design of antimicrobial treatment regimens that minimize the emergence of resistance. Emergence of a resistant bacterial subpopulation within a susceptible wild-type population can be restricted with a regimen using an antibiotic dose that is sufficiently high to inhibit both susceptible and resistant bacteria.

Application of antimicrobial stewardship to optimise management of community acquired pneumonia

The aim of this study was to review the application of antimicrobial stewardship principles to the management of community-acquired pneumonia (CAP). Data from 14 published clinical studies, meta-analyses and practice guidelines regarding the application of antimicrobial stewardship strategies to the management of CAP were identified and analysed. In the context of CAP, application of stewardship strategies (alone or in combination) has been shown to increase physician awareness of guidelines, improve appropriate antimicrobial use and reduce unnecessary antimicrobial prescribing. In addition, application has had a profound favourable impact on patient outcomes, including decreased 30-day mortality and in-hospital mortality rates, reduced length of hospital stay, reduced treatment failure rates and reduced healthcare costs. Antimicrobial stewardship programmes have been demonstrated to successfully increase the level of appropriate antibiotic prescribing, reduce pathogen resistance and improve clinical outcomes in the management of CAP within hospitals. Studies have also shown that adherence to evidence-based guidelines, even at the level of the individual clinician, can have a profound and positive impact on patient outcomes and healthcare costs. Adherence to evidence-based guidelines can have a profound and positive impact on patient outcomes and healthcare costs.

The use of antimicrobial agents after diagnosis of viral respiratory tract infections in hospitalized adults: antibiotics or anxiolytics?

OBJECTIVE

Because extensive antibiotic use by inpatients has been associated with the development of multidrug-resistant organisms, we aimed to determine which variables were associated with the use of antibiotics after viral respiratory tract infection diagnosis among adult patients admitted to the hospital with respiratory symptoms.

METHODS

A retrospective cohort study was conducted at 2 affiliated urban hospitals in Pennsylvania. We identified all adult patients admitted to the hospital during the period from November 1, 2005, through August 1, 2007, with a viral assay positive for influenza A or B, parainfluenza, adenovirus, or respiratory syncytial virus. Among these patients, we identified those who received antibiotics after the diagnosis of viral RTI. Data on demographics; comorbidities; and physical examination, laboratory, and radiographic findings were ascertained to identify risk factors for antimicrobial use among these patients.

RESULTS

A total of 196 hospitalized patients with positive viral assay results were included; 125 of 131 patients administered antibiotics continued to receive them after viral RTI diagnosis. Among 52 patients with an abnormal chest radiograph, 46 continued antibiotic therapy. An abnormal chest radiograph was independently associated with continued antibiotic use (adjusted odds ratio, 4.28 [95% confidence interval, 1.71-10.77]; P = .002). However, the majority of patients (79 of 125 [63%]) who continued antibiotic therapy had normal chest imaging findings. Eight patients (6%) who continued antibiotic therapy and no patients who stopped developed C. difficile infection (95% CI, 1.5-∞; P = .05), but there was no significant difference in length of stay or mortality.

CONCLUSIONS

Antibiotics are commonly used to treat hospitalized patients with known acute viral RTIs. Continued use is strongly associated with abnormal radiograph findings at admission. However, the reasons for continuation of antibiotics in the treatment of the majority of patients with normal radiographs are unclear and may represent inappropriate use.

Impact of bloodstream infections on outcome and the influence of prophylactic oral antibiotic regimens in allogeneic hematopoietic SCT recipients

This study aimed to determine the impact of blood stream infections (BSIs) on outcome of allogeneic hematopoietic SCT (HSCT), and to examine the influence of old (non-levofloxacin-containing) and new (levofloxacin-based) prophylactic antibiotic protocols on the pattern of BSIs. We retrospectively enrolled 246 allogeneic HSCT recipients between January 1999 and June 2006, dividing patients into BSI (within 6 months post-HSCT, n=61) and non-BSI groups (n=185). We found that Gram-negative bacteria (GNB) predominated BSI pathogens (54%). Multivariate analyses showed that patients with a BSI, compared with those without, had a significantly greater 6-month mortality (hazard ratio, 1.75; 95% confidence interval, 1.09-2.82; P=0.021) and a significantly increased length of hospital (LOH) stay (70.8 vs 55.2 days, P=0.014). Moreover, recipients of old and new protocols did not have a significantly different 6-month mortality and time-to-occurrence of BSIs. However, there were significantly more resistant GNB to third-generation cephalosporins and carbapenem in recipients of levofloxacin-based prophylaxis. Our data suggest that BSIs occur substantially and impact negatively on the outcome and LOH stay after allogeneic HSCT despite antibiotic prophylaxis. Levofloxacin-based prophylaxis, albeit providing similar efficacy to non-levofloxacin-containing regimens, may be associated with increased antimicrobial resistance.