Principles of Antibiotic Therapy in Severe Infections: Optimizing the Therapeutic Approach by Use of Laboratory and Clinical Data

Early identification of suspected serious infection among patients afebrile at initial presentation using neural network models and natural language processing: A development and external validation study in the emergency department

OBJECTIVE

To develop and externally validate models based on neural networks and natural language processing (NLP) to identify suspected serious infections in emergency department (ED) patients afebrile at initial presentation.

METHODS

This retrospective study included adults who visited the ED afebrile at initial presentation. We developed four models based on artificial neural networks to identify suspected serious infection. Patient demographics, vital signs, laboratory test results and information extracted from initial ED physician notes using term frequency-inverse document frequency were used as model variables. Models were trained and internally validated with data from one hospital and externally validated using data from a different hospital. Model discrimination was evaluated using area under the receiver operating characteristic curve (AUC) and 95% confidence intervals (CIs).

RESULTS

The training, internal validation, and external validation datasets comprised 150,699, 37,675, and 85,098 patients, respectively. The AUCs (95% CIs) for Models 1 (demographics + vital signs), 2 (demographics + vital signs + initial ED physician note), 3 (demographics + vital signs + laboratory tests), and 4 (demographics + vital signs + laboratory tests + initial ED physician note) in the internal validation dataset were 0.789 (0.782-0.796), 0.867 (0.862-0.872), 0.881 (0.876-0.887), and 0.911 (0.906-0.915), respectively. In the external validation dataset, the AUCs (95% CIs) of Models 1, 2, 3, and 4 were 0.824 (0.817-0.830), 0.895 (0.890-0.899), 0.879 (0.873-0.884), and 0.913 (0.909-0.917), respectively. Model 1 can be utilized immediately after ED triage, Model 2 can be utilized after the initial physician notes are recorded (median time from ED triage: 28 min), and Models 3 and 4 can be utilized after the initial laboratory tests are reported (median time from ED triage: 68 min).

CONCLUSIONS

We developed and validated models to identify suspected serious infection in the ED. Extracted information from initial ED physician notes using NLP contributed to increased model performance, permitting identification of suspected serious infection at early stages of ED visits.

Clinical and economic evaluation of blood culture whole process optimisation in critically ill adult patients with positive blood cultures

OBJECTIVES

Optimising blood culture processing is important to ensure that bloodstream infections are accurately diagnosed while minimising adverse events caused by antibiotic abuse. This study aimed to evaluate the impact of optimised blood culture processes on antibiotic use, clinical outcomes and economics in intensive care unit (ICU) patients with positive blood cultures.

METHODS

From March 2020 to October 2021, this microbiology laboratory implemented a series of improvement measures, including the clinical utility of Fastidious Antimicrobial Neutralization (FAN® PLUS) bottles for the BacT/Alert Virtuo blood culture system, optimisation of bottle reception, graded reports and an upgraded laboratory information system. A total of 122 ICU patients were included in the pre-optimisation group from March 2019 to February 2020, while 179 ICU patients were included in the post-optimisation group from November 2021 to October 2022.

RESULTS

Compared with the pre-optimisation group, the average reporting time of identification and antimicrobial sensitivity was reduced by 16.72 hours in the optimised group. The time from admission to targeted antibiotic therapy within 24 hours after receiving both the Gram stain report and the final report were both significantly less in the post-optimisation group compared with the pre-optimisation group. The average hospitalisation time was reduced by 6.49 days, the average antimicrobial drug cost lowered by $1720.85 and the average hospitalisation cost by $9514.17 in the post-optimisation group.

CONCLUSIONS

Optimising blood culture processing was associated with a significantly increased positive detection rate, a remarkable reduction in the length of hospital stay and in hospital costs for ICU patients with bloodstream infections.

Impact of inadequate empirical antibiotic treatment on outcome of non-critically ill children with bacterial infections

BACKGROUND

The impact of inadequate empirical antibiotic treatment on patient outcomes and hospitalization duration for non-life-threatening infections in children remains poorly understood. We aimed to assess the effects of inadequate empirical antibiotic treatment on these factors in pediatric patients.

METHODS

The medical records of children admitted for infectious diseases with bacteria isolated from sterile sites between 2018 and 2020 were retrospectively reviewed. Patients who received adequate empirical treatment were compared with those who received inadequate treatment in terms of demographic, clinical, and laboratory variables.

RESULTS

Forty-eight patients who received inadequate empirical antimicrobial treatment were compared to 143 patients who received adequate empirical treatment. Inadequate empirical antimicrobial treatment did not significantly affect the length of hospital stay or the incidence of complications in non-critically ill children with bacterial infections. Younger age and underlying renal abnormalities were identified as risk factors for inadequate antimicrobial treatment, while associated bacteremia was more common in the adequate antimicrobial treatment group.

CONCLUSIONS

inadequate antibiotic treatment did not affect the outcomes of non-critically ill children with bacterial infectious diseases. Therefore, routine empirical broad-spectrum treatment may not be necessary for these cases, as it can lead to additional costs and contribute to antibiotic resistance. Larger prospective studies are needed to confirm these findings.

Journey of technological advancements in the detection of antimicrobial resistance

Increased uses rather an extensive misuse of antibiotics due to easy availability and easy access have resulted in antibiotic resistance as a global crisis. The speed of discovery of new antibiotics has slowed down recently. Therefore, there is a need to reduce the rate of increase in resistance against the presently available antibiotics, or else many infections may be left untreatable or difficult to be treated due to the high prevalence of resistance. The judicious use of broad-spectrum antibiotics can control the increase in resistance profile. Various techniques are presently being used for the detection of antibiotic resistance. Conventional phenotypic methods are preferred that are highly reliable but are much more time-consuming. The patients cannot spare more time as the infection keeps increasing. The results with genotypic methods are obtained within 24 h as compared to phenotypic methods. Hence, recent molecular methods like qPCR can be used for detection. In this review, we present an overview of various methods useful for the detection of antibiotic resistance, with emphasis on their advantages and limitations. The review also emphasizes qPCR to be the most preferred method out of all because of various advantageous factors.

Development of machine learning algorithms for scaling-up antibiotic stewardship

BACKGROUND

Antibiotic stewardship programs (ASP) aim to reduce inappropriate use of antibiotics, but their labor-intensive nature impedes their wide adoption. The present study introduces explainable machine learning (ML) models designed to prioritize inpatients who would benefit most from stewardship interventions.

METHODS

A cohort of inpatients who received systemic antibiotics and were monitored by a multidisciplinary ASP team at a tertiary hospital in the Republic of Korea was assembled. Data encompassing over 130,000 patient-days and comprising more than 160 features from multiple domains, including prescription records, laboratory, microbiology results, and patient conditions was collected.Outcome labels were generated using medication administration history: discontinuation, switching from intravenous to oral medication (IV to PO), and early or late de-escalation. The models were trained using Extreme Gradient Boosting (XGB) and light Gradient Boosting Machine (LGBM), with SHapley Additive exPlanations (SHAP) analysis used to explain the model's predictions.

RESULTS

The models demonstrated strong discrimination when evaluated on a hold-out test set(AUROC - IV to PO: 0.81, Early de-escalation: 0.78, Late de-escalation: 0.72, Discontinue: 0.80). The models identified 41%, 16%, 22%, and 17% more cases requiring discontinuation, IV to PO, early and late de-escalation, respectively, compared to the conventional length of therapy strategy, given that the same number of patients were reviewed by the ASP team. The SHAP results explain how each model makes their predictions, highlighting a unique set of important features that are well-aligned with the clinical intuitions of the ASP team.

CONCLUSIONS

The models are expected to improve the efficiency of ASP activities by prioritizing cases that would benefit from different types of ASP interventions along with detailed explanations.

Antimicrobial Stewardship in the Hospital Setting: A Narrative Review

The increasing global threat of antibiotic resistance, which has resulted in countless fatalities due to untreatable infections, underscores the urgent need for a strategic action plan. The acknowledgment that humanity is perilously approaching the "End of the Miracle Drugs" due to the unjustifiable overuse and misuse of antibiotics has prompted a critical reassessment of their usage. In response, numerous relevant medical societies have initiated a concerted effort to combat resistance by implementing antibiotic stewardship programs within healthcare institutions, grounded in evidence-based guidelines and designed to guide antibiotic utilization. Crucial to this initiative is the establishment of multidisciplinary teams within each hospital, led by a dedicated Infectious Diseases physician. This team includes clinical pharmacists, clinical microbiologists, hospital epidemiologists, infection control experts, and specialized nurses who receive intensive training in the field. These teams have evidence-supported strategies aiming to mitigate resistance, such as conducting prospective audits and providing feedback, including the innovative 'Handshake Stewardship' approach, implementing formulary restrictions and preauthorization protocols, disseminating educational materials, promoting antibiotic de-escalation practices, employing rapid diagnostic techniques, and enhancing infection prevention and control measures. While initial outcomes have demonstrated success in reducing resistance rates, ongoing research is imperative to explore novel stewardship interventions.

Pilot Study: Impact of a Pharmacist-Led 48-Hour Antibiotic Time-Out on Antibiotic Utilization and Outcome Measures in a Community Teaching Hospital

Purpose: The objective of this study is to determine the impact of a 48-hour time-out on the utilization of targeted empiric intravenous (IV) antibiotics through a systematic approach. Methods: This is a single-center, prospective, interventional study approved by the Institutional Review Board. Study groups were stratified into a control and intervention arm. Inclusion criteria consisted of patients 18 years of age or greater, on targeted broad-spectrum IV antibiotics for more than 24 hours: daptomycin, ertapenem, meropenem, piperacillin-tazobactam, vancomycin. Exclusion criteria included febrile neutropenic, pregnant, critically ill, and surgical prophylactic patients. Targeted interventions made by pharmacists included: IV to oral conversions, dose optimizations/adjustments, and de-escalations. Primary endpoints were days of therapy per 1000 patient days (DOT/1000), days of therapy at risk per 1000 patient days (DOT/1000 DAR), and de-escalation rates. Results: Table 1 depicts a total 88.69% mean reduction of DOT/1000 of the intervention arm for vancomycin, piperacillin/tazobactam, and meropenem (P-value <.0001) when compared to the control arm. Table 2 depicts a total 88.86% mean reduction of DOT/1000 DAR of the intervention arm for vancomycin, piperacillin/tazobactam, and meropenem (P-value <.0001) when compared to control. Table 3 shows a 77.11% increase in total de-escalation rates (P-value = .0107) in the intervention group when compared to control group (63.52%). Conclusion: This study displays the essential role that pharmacists play in antibiotic stewardship. This study further reveals that the stewarding tool utilized contributed to significant reductions in the usage of targeted empiric intravenous antibiotics.

Implementing Alfred60AST in a clinical lab: Clinical impact on the management of septic patients and financial analysis

INTRODUCTION

Sepsis is an important cause of morbidity and mortality. An accelerated microbiology diagnosis is crucial in order to reduce the time to initiate targeted antibiotic therapy. The Alfred60AST system is able to provide phenotypic Antimicrobial Susceptibility Testing (AST) results within hours. This study has two objectives: assess the clinical impact of this technology and determine its cost-effectiveness.

METHODS

During a ten-week period, all new enterobacterial or enterococcal bloodstream infection was analyzed with the Alfred60AST system, in parallel with routine methods. Its impact on the clinician's therapeutic strategy was studied. In order to assess the financial and practical aspects of the method, an analysis of the extracosts and a survey of the technical staff were conducted.

RESULTS

Fifty-three cases of bacteriemia were included. For the Enterobacteriaceae bacteriemias, a clinical impact was shown in 18.9% of the cases (e.g, treatment modification). The financial analysis highlighted an increase in costs (+38% for Enterobacteriaceae, +50% for Enterococci), compared to the theoretical costs reported by the firm, due to the workflow and the volumes of samples used. Finally, results of the technical staff survey were favorable in terms of ease of use of the system.

CONCLUSION

In addition to its ease of use, the Alfred60AST system is able to provide an AST in a record time. This study shows a real interest of the technique in the therapeutic management of patients with enterobacterial sepsis. However, its routine implementation requires an increase of the analyzed volumes as well as a 24/7 organization of the laboratory in order to be profitable.

Digital Antimicrobial Stewardship Decision Support to Improve Antimicrobial Management

OBJECTIVES

We sought to create a digital application to support clinicians in empiric and pathogen-directed antibiotic ordering based on local susceptibility patterns and evidence-based treatment durations, thereby promoting antimicrobial stewardship.

METHODS

We formed a multidisciplinary team that met bimonthly from 2017 to 2018 to design and construct a web-based antimicrobial stewardship platform called Antibiogram + . We used an iterative and agile technical development process with frequent feedback from clinicians.

RESULTS

Antibiogram+ is an online tool, accessible via the electronic health record and hospital intranet, which offers institutional antibiotic susceptibilities for major pathogens, recommendations for empiric antibiotic selection and treatment durations for common pediatric conditions, antimicrobial dosing and monitoring guidance, and links to other internal clinical decision support resources. The tool was accessed 11,823 times with 492 average monthly views during the first 2 years after release. Compared with use of a preexisting print antibiogram and dosing card, pediatric residents more frequently reported "often" being sure of antibiotic dosing with Antibiogram+ (58 vs. 15%, p < 0.01). Respondents also reported improved confidence in choice of antibiotic, but this finding did not reach statistical significance (55 vs. 35%, p = 0.26).

CONCLUSION

We report the successful development of a digital antimicrobial stewardship platform with consistent rates of access during the first 2 years following release and improved provider comfort with antibiotic management.

Karunakaran R, Abdul Jabar K, Ponnampalavanar S, Chong CW, Teh CSJ. A retrospective study on molecular epidemiology trends of carbapenem resistant Enterobacteriaceae in a teaching hospital in Malaysia

BACKGROUND

Carbapenem resistant Enterobacteriaceae (CRE) has rapidly disseminated worldwide and has become a global threat to the healthcare system due to its resistance towards "last line" antibiotics. This study aimed to investigate the prevalence of CRE and the resistance mechanism as well as the risk factors associated with in-hospital mortality.

METHODS

A total of 168 CRE strains isolated from a tertiary teaching hospital from 2014-2015 were included in this study. The presence of carbapenemase genes and minimum inhibitory concentration of imipenem, meropenem and colistin were investigated. All carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) strains were characterised by PFGE. The risk factors of patients infected by CRE associated with in-hospital mortality were determined statistically.

RESULTS

The predominant CRE species isolated was K. pneumoniae. The carbapenemases detected were blaOXA-48, blaOXA-232, blaVIM and blaNDM of which blaOXA-48 was the predominant carbapenemase detected among 168 CRE strains. A total of 40 CRE strains harboured two different carbapenemase genes. A total of seven clusters and 48 pulsotypes were identified among 140 CRKp strains. A predominant pulsotype responsible for the transmission from 2014 to 2015 was identified. Univariate statistical analysis identified that the period between CRE isolation and start of appropriate therapy of more than 3 days was statistically associated with in-hospital mortality.

Antimicrobial Stewardship Program: Reducing Antibiotic's Spectrum of Activity Is not the Solution to Limit the Emergence of Multidrug-Resistant Bacteria

Overconsumption of antibiotics in hospitals has led to policy implementation, including the control of antibiotic prescriptions. The impact of these policies on the evolution of antimicrobial resistance remains uncertain. In this work, we review the possible limits of such policies and focus on the need for a more efficient approach. Establishing a causal relationship between the introduction of new antibiotics and the emergence of new resistance mechanisms is difficult. Several studies have demonstrated that many resistance mechanisms existed before the discovery of antibiotics. Overconsumption of antibiotics has worsened the phenomenon of resistance. Antibiotics are responsible for intestinal dysbiosis, which is suspected of being the source of bacterial resistance. The complexity of the intestinal microbiota composition, the impact of the pharmacokinetic properties of antibiotics, and the multiplicity of other factors involved in the acquisition and emergence of multidrug-resistant organisms, lead us to think that de-escalation, in the absence of studies proving its effectiveness, is not the solution to limiting the spread of multidrug-resistant organisms. More studies are needed to clarify the ecological risk caused by different antibiotic classes. In the meantime, we need to concentrate our efforts on limiting antibiotic prescriptions to patients who really need it, and work on reducing the duration of these treatments.

Performance of QMAC-dRASTTM (Direct Rapid Antimicrobial Susceptibility Testing) - a Newcomer in Phenotypic Automatic AST

Objective:

QMAC-dRASTTM is a phenotypic automatized Antibiotic Susceptibility Testing (AST) system based on microfluidic chip technology enabling observation of changes in a single bacterial cell under antibiotic treatment conditions. The 96 wells plate with dried antibiotics comprises 19 and 17 antibiotics for the Gram-Negatives (GNs) and Gram-Positives (GPs), respectively. Categorical (Sensitive, Intermediate or Resistant) results were compared to results obtained by our laboratory standard susceptibility testing procedure and given as Categorical Agreement (CA).

Methods:

In a 3-month period (2019/2020), blood cultures detected positive were included. Excluded were known off-panel strains of QMAC-dRASTTM, such as Gram-positive bacilli, Streptococcus and Candida species. Percentages of CA (CA, %) between QMAC-dRASTTM and routine testing methods used in the laboratory (EUCAST disc diffusion and/or etest/Broth Micro Dilution MIC), were calculated.

Results:

255 positive blood cultures from as many patients were examined. Of the positive blood culture strains, 144 were GNs, and 111 were GPs. An overall combined CA,% of 96.3 (2410 of 2502 determinations) was obtained, and discrepancies were noted in 92 of 2502 test results (3.7%). The percentage of very major errors (VMEs) was 0.7% for GNs and 2.2% for GPs. For 87% of blood culture specimens examined, susceptibility reports were available within 6-7 hours.

Conclusion:

The high CA,% for as well GNs as GPs are promising. The presented time to report data obtained by QMAC-dRASTTM in this study being of 3-8 hours for blood culture specimens examined strongly support a further possible improvement in the workflow for handling blood stream infections.

Do rapid diagnostic methods improve antibiotic prescribing in paediatric bacteraemia?

AIM

Rapid blood culture pathogen identification facilitated by matrix-assisted laser desorption ionisation time-of-flight and GeneXpert has the potential to improve antibiotic prescribing. This study investigates the impact of these rapid diagnostics on the timeliness of effective and optimal antibiotic prescribing in paediatric patients with bacteraemia.

METHODS

A single centre retrospective cohort study was performed comparing paediatric bacteraemia cases pre- and post-rapid diagnostic implementation. Primary outcomes were the proportion of cases receiving, and median time to administration of effective and optimal antibiotics from blood culture collection. Secondary outcomes included hospital length of stay, intensive care unit admissions, and all-cause mortality.

RESULTS

A total of 255 bacteraemia cases were subject to final data analysis, 129 in the control cohort (pre-implementation of rapid diagnostics) and 126 in the rapid diagnostics cohort. The median time to effective (2.3 vs. 1.8 h, P = 0.20) and optimal therapy (44.4 vs. 39.1 h, P = 0.66) did not differ significantly between the cohorts. There was also no significant difference found in the number of cases reaching effective (120 vs. 116, P = 0.77) and optimal therapy (66 vs. 62, P = 0.76), length of stay (7 vs. 9 days), all-cause mortality (1.6 vs. 1.6%) and number of intensive care unit admissions (20 vs. 15).

CONCLUSION

The implementation of rapid diagnostics, when used in isolation, resulted in no improvement in antibiotic prescribing or patient clinical outcomes. To be effective, rapid diagnostics must be coupled with active real-time antimicrobial stewardship promotion, de-escalation or modification based on early laboratory results.

Appropriateness of Antibiotics Use and Associated Factors in Hospitalized Patients at University of Gondar Specialized Hospital, Amhara, Ethiopia: Prospective Follow-up Study

Background:

Appropriate antibiotic use means that the patient receives the appropriate drug at adequate doses and duration for a susceptible pathogen. This improves the effectiveness of antibiotic therapy and prevents the emergence of resistant pathogens. Thus, this study aimed to assess the appropriateness of antibiotics use and associated factors among hospitalized patients.

Methods:

A hospital-based prospective follow-up study was conducted in internal medicine. Data were collected by chart review and interview of prescribers and patients using a pre-tested questionnaire derived from RAND modified Delphi method. Appropriate antibiotic use means that the patient receives the drug based on culture result at the right time in adequate doses and duration. Frequencies and percentage distribution of dependent variables were analyzed. Moreover, bivariate and multivariate analyses were used to assess the factors influencing factors.

Result:

Of the 303 study participants, the mean age was44.36 ± 1.07 years and the majority 173 (57.1%) of the participants were females. The appropriateness of antibiotics use among hospitalized patients was 26 (8.6%). Males have used antibiotics more appropriately than females [5.99 (Adjusted odd ration (AOR) 95% CI 2.00-7.98)], while employed study participants were used antibiotics more appropriately than nonemployees [7.29 (AOR 95% CI 1.34-9.58)]. Moreover, patients who received antibiotics after blood culture [2.74 (AOR 95% CI 1.09-8.37)] and cerebrospinal fluid culture [5.82 (AOR 95% CI 1.84-5.63)] were used antibiotics more appropriately than patients who received antibiotics without culture. In addition, patients who believe that the prescribed antibiotics prevent complication of the disease [4.21 (AOR 95% CI 1.33-7.35)] were used antibiotics more appropriately than those who didn’t understand the use of antibiotics.

Conclusion:

The appropriateness of antibiotics use was very low in the study area. Patient gender, ethnicity, source of income, patient’s belief in antibiotics, and specimen cultures were significantly associated with the appropriateness of antibiotics use.

The role of new antimicrobials for Gram-negative infections in daily clinical practice

PURPOSE OF REVIEW

To discuss a possible clinical reasoning for treating resistant Gram-negative bacteria (GNB) infections in daily clinical practice, as well as developing a research agenda for the field.

RECENT FINDINGS

Novel agents, both belonging to β-lactams and to other classes of antimicrobials, have recently become available, likely replacing polymyxins or polymyxin-based combination regimens as the preferred choices for the first-line treatment of severe resistant GNB infections in the near future.

SUMMARY

The peculiar characteristics of novel agents for severe resistant GNB infections have abruptly made the structure of previous therapeutic algorithms somewhat obsolete, in view of the differential activity of most of them against different classes of carbapenemases. Furthermore, other agents showing activity against resistant GNB are in late phase of clinical development. Optimizing the use of novel agents in order both to guarantee the best available treatment to patients and to delay the emergence and spread of resistance is an important task that cannot be postponed, especially considering the unavailability of well tolerated and fully efficacious options for treating resistant GNB infections that we faced in the last 15 years.

A Rapid Flow Cytometric Antimicrobial Susceptibility Assay (FASTvet) for Veterinary Use - Preliminary Data

A rapid flow cytometric antimicrobial susceptibility test for bacteria isolated from companion animals – the FASTvet assay, developed by FASTinov^®, was evaluated. Bacterial strains isolated from different biological samples of companion animals with infectious diseases in progress were obtained from several veterinary clinical laboratories across the country. A total of 115 strains, comprising 65 Gram-negative and 50 Gram positive isolates, were incubated with 13 antimicrobial drugs (ampicillin, amoxicillin-clavulanic acid, piperacillin-tazobactam, cefpodoxime, imipenem, enrofloxacin, gentamicin, amikacin for Gram-negative; penicillin, cefoxitin, enrofloxacin, vancomycin and ampicillin for Gram-positive) at breakpoint concentrations following CLSI protocol (CLSI Vet 01, 2018) for 1 h and analyzed by flow cytometry. The overall categorical agreement was 95.6% in case of Gram-negative and of 96.7% in Gram-positive isolates when compared to microdilution. FASTvet kits contribute to reduce the turnaround time (2 vs. 24 h) with early determination of the antimicrobial susceptibility profile. The correct and rapid choice of the target antibiotic therapy, will have a positive impact on animal care, contributing for preventing antimicrobial resistance. In conclusion, FASTinov^® vet kits showed an excellent performance, both for Gram-negative and Gram-positive isolates encouraging us to enlarge the sample size and planning multicentric studies.

ERS International Congress, Madrid, 2019: highlights from the Respiratory Infections Assembly

The European Respiratory Society (ERS) International Congress organised in Madrid, Spain, in 2019 welcomed >22 000 participants from 134 countries. For each ERS assembly, an impressive number of abstracts were submitted. The topics covered by Assembly 10 (Respiratory Infections and Tuberculosis) were included this year in the top five research areas with the most submitted abstracts, with a total of 424 abstracts accepted for presentation. As it would be difficult for any delegate to stay up to date with all the scientific advances in the field, we wanted to highlight three of the Congress sessions that included presentations on respiratory infections and tuberculosis that we deemed as important and we hope the readers will consider this material of great interest.

Economic Burden Of Inappropriate Empiric Antibiotic Therapy: A Report From Southern Iran

Introduction

Widespread inappropriate antibiotic prescribing by healthcare professionals in the hospital setting is a great concern that may cause many undesirable consequences. Adherences to antibiotic guidelines have proven to be a simple and effective intervention to guide the choice of appropriate empiric antibiotic regimens and reduce the unnecessary variations in the practice among practitioners. The objective of this study was to evaluate the prescription patterns of empiric antibiotic therapy in relation to treatment guidelines and the economic burden of discordance with guidelines in a major referral Iranian university hospital.

Method

Hospital records of hospitalized patients with empiric antibiotic prescription, from September 2016 to February 2017 were reviewed. The process consisted of comparing empiric antimicrobial administration with institutional guidelines for each patient by a clinical pharmacist and an infectious disease specialist to evaluate the appropriate utilization of antibiotics. Adherence to guideline, the cost of antibiotics usage for each patient and the excess cost consequent from discordance with guideline was calculated.

Results

The most inappropriate prescribed antibiotics were carbapenems and aminoglycosides. Overall guideline adherence was 27.8%. Frequency of antibiotic usage incompatibility with the guidelines on the basis of dosing interval, duration of therapy and drug indication were 31.46%, 29.44% and 19.36%, respectively. General surgery and internal medicine wards had the least and the most inappropriate antibiotic administration, respectively. Totally antibiotic usage cost was 578,959.39 USD (24,316,294,800 Iranian Rials, IRR) for 6 months, which the excess costs of inappropriate antibiotic prescribing, was 471,319.69 USD (19,795,427,225 IRR). The estimated annual excess cost is 942,639.38 USD (39,590,854,450 IRR).

Conclusion

In this research, physicians’ adherence with guidelines for empiric antibiotic therapy was low which was led to 471,319.69 USD excess costs. These results urge institution policy makers to develop guidelines to ensure active dissemination and implementation of them to decrease inappropriate antibiotic usage.

Antibiotic prescribing practices in paediatric septic shock in a tertiary care hospital in a resource limited setting: an audit

Introduction

Early empiric broad spectrum antibiotic administration in children with septic shock improves outcome. Knowledge on possible bacterial aetiology, drug resistance pattern and rational choice of antibiotics is crucial in management of septic shock.

Methods

This was an audit carried out among 50 (0- 5 years age) children admitted with septic shock at the Kenyatta National Hospital between October to December 2016. A standard questionnaire was used for data collection as per the Surviving Sepsis Guideline. Data were stored in Excel and analyzed in Strata 12.

Results

Of the 50 admitted children with septic shock 86% were less than one-year age. Samples for blood cultures were removed from 12(24%) prior to administration of antibiotics. Blood culture bottles were unavailable in 80%. All children received antibiotics. Antibiotics were initiated in 44(88%) in the golden hour of diagnosis of septic shock. Monotherapy with cephalosporins 30 (60%) was the commonest choice of initial antibiotic. Antibiotics were changed in 7(22.6%) and 1(5.3%) at 24 and 48 hours respectively due to clinical deterioration. Over mortality at 72 hours was 35 (70%). All the 9 children initiated on meropenem monotherapy on admission died.

Conclusion

The majority of patients with septic shock were under one-year age. All patients were initiated on antibiotics. Blood cultures were done in a quarter of the patients. Monotherapy with cephalosporin was the commonest choice of antibiotic. De-escalation was not well accomplished due to microbiological culture limitation. There was no standard antibiotic choice hence antibiotic use in septic shock needs to be included in the paediatric local guidelines.

Current and emerging pharmacotherapy for the treatment of infections following open-heart surgery

INTRODUCTION

Patients undergoing open-heart surgery may suffer from postoperative complications, including severe infections. Antimicrobials to treat infectious complications in this population should be selected thoughtfully, taking into account three different and fundamental issues: (i) the site of infection; (ii) the suspected or proven causative agent and its susceptibility pattern; and (iii) the risk of suboptimal pharmacokinetic characteristics and potential toxicity of the chosen drug/s.

AREAS COVERED

The present narrative review summarizes the current and future antimicrobial options for the treatment of infections developing after open-heart surgery.

EXPERT OPINION

The pharmacological treatment of infections developing in cardiac surgery patients poses peculiar challenges, including the need for an active empirical therapy for severe events such as bloodstream infections, deep sternal wound infections, or early-onset postoperative prosthetic endocarditis. In addition, the risk for multidrug-resistant pathogens should also be taken into account in endemic areas. A multidisciplinary evaluation on a patient-by-patient basis, deeply involving infectious diseases specialists and cardiothoracic surgeons, remains essential for appropriately balancing both short-term and long-term risks and benefits of any possible surgical reintervention in combination with adequate pharmacotherapy.

Control of Infectious Diseases in the Era of European Clinical Microbiology Laboratory Consolidation: New Challenges and Opportunities for the Patient and for Public Health Surveillance

Many new innovative diagnostic approaches have been made available during the last 10 years with major impact on patient care and public health surveillance. In parallel, to enhance the cost-effectiveness of the clinical microbiology laboratories (CMLs), European laboratory professionals have streamlined their organization leading to amalgamation of activities and restructuring of their professional relationships with clinicians and public health specialists. Through this consolidation process, an operational model has emerged that combines large centralized clinical laboratories performing most tests on one high-throughput analytical platform connected to several distal laboratories dealing locally with urgent analyses at near point of care. The centralization of diagnostic services over a large geographical region has given rise to the concept of regional-scale "microbiology laboratories network." Although the volume-driven cost savings associated with such laboratory networks seem self-evident, the consequence(s) for the quality of patient care and infectious disease surveillance and control remain less obvious. In this article, we describe the range of opportunities that the changing landscape of CMLs in Europe can contribute toward improving the quality of patient care but also the early detection and enhanced surveillance of public health threats caused by infectious diseases. The success of this transformation of health services is reliant on the appropriate preparation in terms of staff, skills, and processes that would be inclusive of stakeholders. In addition, rigorous metrics are needed to set out more concrete laboratory service performance objectives and assess the expected benefits to society in terms of saving lives and preventing diseases.

Rapid identification of pathogens responsible for necrotizing fasciitis on an integrated microfluidic system

Necrotic fasciitis (NF) is a particularly aggressive and serious infection of the fascia that can penetrate into the musculature and internal organs, resulting in death if not treated promptly. In this work, an integrated microfluidic system composed of micropumps, microvalves, and micromixers was used to automate the detection of pathogens associated with NF. The entire molecular diagnostic process, including bacteria isolation, lysis, nucleic acid amplification and optical detection steps, was enacted on this developed system. Mannose binding lectin coated magnetic beads were first used as probes to isolate all bacteria in a sample. In this work, polymerase chain reaction assays featuring primers specific to genes from each of four NF-causing bacteria (Vibrio vulnificus, Aeromonas hydrophila, and methicillin-sensitive and resistant Staphylococcus aureus) were used to rapidly and exclusively verify the presence of the respective bacterial strains, and the limits of detection were experimentally found to be 11, 1960, 14, and 11 400 colony forming units/reaction, respectively; all values reflect improvement over ones reported in literature. This integrated microfluidic chip may then be valuable in expediting diagnosis and optimizing treatment options for those with NF; such diagnostic improvements could ideally diminish the need for amputation and even reduce the morality rate associated with this life-threatening illness.

Identification of microorganisms grown in blood culture flasks using liquid chromatography–tandem mass spectrometry

Aim: Bloodstream infections are a common cause of disease and a fast and accurate identification of the causative agent or agents of bloodstream infections would aid the start of adequate treatment. Materials & methods: A liquid chromatography–tandem mass spectrometry (LC–MS/MS) shotgun proteomics method was developed for the identification of bacterial species directly from blood cultures that were simulated by inoculating blood culture bottles with single or multiple clinically relevant microorganisms. Results: Using LC–MS/MS, the single species were correctly identified in 100% of the blood cultures, whereas for polymicrobial infections, 78% of both species were correctly identified in blood cultures. Conclusion: The LC–MS/MS method allows for the identification of the causative agent of positive blood cultures.

Shifting trends in bacteriology and antimicrobial resistance among gastrointestinal fistula patients in China: an eight-year review in a tertiary-care hospital

Background

The purpose of this study was to determine the shifting trends in bacteriology and antimicrobial resistance of infectious specimens isolated from gastrointestinal (GI) fistula patients over eight years in China.

Methods

We retrospectively reviewed the microbial records of intra-abdominal specimens at a teaching hospital from 2008 to 2015. Study period was divided into the first half (2008–2011) and the second half (2012–2015). All isolates underwent antibiotic susceptibility testing by the micro dilution method.

Results

A total of 874 intra-abdominal isolates were consecutively collected from 502 GI fistula patients (mean age, 46.5 years, 71.1% male) during the study period. Patients in the second study period (2012–2015) were older (>65 years) and more likely to have experienced cancer. Over the entire study period, most infections were caused by E. coli (24.2%) and K. pneumonia (14.1%). There was a significant decrease in the proportion E. coli isolates that were extended- spectrum beta-lactamase (ESBL)-positive (P = 0.026). The proportion of E. coli resistant to imipenem increased from 14.3% in 2008–2011 to 25.9% in 2012–2015 (P = 0.037). Imipenem resistance prevalence was higher in ESBL-negative bacteria than ESBL-positive bacteria for both E. coli and K. pneumonia (P < 0.001). In Enterococcus, significant increase in resistance to ampicillin (P = 0.01) and moxifloxacin (P = 0.02) over time were observed. In Staphylococcus and fungi, rates of antibiotic resistance did not significantly change over the study period.

Conclusions

Gram-negative bacteria predominated as causative agents of intra-abdominal infections in GI fistula patients, and there was an increase in levels of resistance to certain antibiotics, particularly carbapenems. Infection control and source control are important tools available to surgeons to prevent the emergence of antibiotic-resistant pathogens.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2744-7) contains supplementary material, which is available to authorized users.

Modeling antibiotic treatment in hospitals: A systematic approach shows benefits of combination therapy over cycling, mixing, and mono-drug therapies

Multiple treatment strategies are available for empiric antibiotic therapy in hospitals, but neither clinical studies nor theoretical investigations have yielded a clear picture when which strategy is optimal and why. Extending earlier work of others and us, we present a mathematical model capturing treatment strategies using two drugs, i.e the multi-drug therapies referred to as cycling, mixing, and combination therapy, as well as monotherapy with either drug. We randomly sample a large parameter space to determine the conditions determining success or failure of these strategies. We find that combination therapy tends to outperform the other treatment strategies. By using linear discriminant analysis and particle swarm optimization, we find that the most important parameters determining success or failure of combination therapy relative to the other treatment strategies are the de novo rate of emergence of double resistance in patients infected with sensitive bacteria and the fitness costs associated with double resistance. The rate at which double resistance is imported into the hospital via patients admitted from the outside community has little influence, as all treatment strategies are affected equally. The parameter sets for which combination therapy fails tend to fall into areas with low biological plausibility as they are characterised by very high rates of de novo emergence of resistance to both drugs compared to a single drug, and the cost of double resistance is considerably smaller than the sum of the costs of single resistance.

Direct identification from positive blood broth culture by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS)

Bloodstream infections (BSIs) are among the most concerning bacterial infections. They are one of the leading causes of morbidity and mortality, and occur in 30–70% of critical care patients. The prompt identification of the causative microorganism can help choosing the appropriate antimicrobial therapy that will lead to better clinical outcomes. Blood culture is one of the most relevant tests for microbiological diagnosis of bacterial infections. The introduction of the MALDI-TOF microbiological diagnosis significantly decreased the time of identifying microorganisms. However, it depends on the growth on solid culture medium. In this study, 538 bottles of positive blood cultures were evaluated to test the accuracy of an in house modified protocol. The study sample consisted of 198 Gram-negative and 350 Gram-positive bacteria. In all, 460 (83.94%) species were identified based on the direct plate findings. The protocol allowed the identification of 185/198 (93.43%) of the Gram-negative bacteria, including aerobes, anaerobes, and non-fermenters, and 275/350 (78.85%) of the Gram-positive bacteria. The proposed method has the potential to provide accurate results in comparison to the traditional method with the potential to reduce the turnaround time for the results and optimize antimicrobial therapy in BSI.

Detection and DNA quantification of Enterococcus casseliflavus in a foal with septic meningitis

CASE DESCRIPTION A 3-month-old 180-kg (396-lb) Hanoverian colt was examined because of fever, lethargy, inappetence, drooping of the left ear, and stiff neck posture. Initial treatment included empirical antimicrobial treatment and NSAIDs. CLINICAL FINDINGS Initial findings were consistent with CNS anomalies. Endoscopy revealed hyperemia, ecchymosis, and some mucopurulent exudate in the right guttural pouch. Hematologic findings were consistent with neutrophilic inflammation. On the third day of hospitalization, severe neurologic signs were observed. Computed tomography of the skull revealed a comminuted fracture of the axial aspect of the right mandibular condyle. Examination of CSF revealed turbidity, xanthochromia, and intracellular and extracellular cocci, consistent with septic meningitis. After DNA extraction from blood and CSF, sequenced products from a PCR assay for the bacterial 16S rRNA gene were 99% identical to Enterococcus casseliflavus. Microbial culture of CSF and blood samples yielded bacteria with Enterococcus spp morphology; antimicrobials were selected on the basis of susceptibility testing that identified the isolate as vancomycin resistant. A quantitative PCR assay was used to estimate Enterococcus DNA concentrations in CSF and blood. TREATMENT AND OUTCOME Treatment for E casseliflavus meningitis, including trimethoprim-sulfadiazine and ampicillin sodium administration, resulted in resolution of clinical signs. Culture of CSF and blood samples after 12 days of the targeted treatment yielded no growth. CLINICAL RELEVANCE To the authors' knowledge, this was the first report of E casseliflavus meningitis in a horse. Treatment was successful; vancomycin-resistant enterococci can be a clinical problem and may potentially be zoonotic.

Shortening the incubation time for antimicrobial susceptibility testing by disk diffusion for Enterobacteriaceae: how short can it be and are the results accurate?

The standard incubation time for antimicrobial susceptibility testing (AST) by disk diffusion is primarily based on laboratory working hours rather than growth and kill characteristics of bacteria. Faster AST results could result in better patient outcomes and reduced costs by initiating earlier appropriate therapy. The earliest possible reading moment for disk diffusion using established disk zone diameter breakpoints for Enterobacteriaceae was determined with a special focus on the accuracy of the results. A total of 88 Enterobacteriaceae challenge isolates, including isolates with specific resistance mechanisms such as extended-spectrum β-lactamase (ESBL), were subjected to disk diffusion with 15 antibiotics. Hourly images were automatically produced by an incubator/camera combination from 1 h to 20 h. Disk zones were plotted over time for all combinations. Essential and categorical agreement rates using the final reading after 20 h of incubation as a reference were calculated for every hour. In total, 1320 antibiotic-micro-organism combinations were tested. Clear growth with readable inhibition zones was visible after 6 h of incubation for the majority (95.8%) of plates and after 7 h for all incubated plates. However, zone sizes changed significantly after those time points for a number of strains. After 10 h of incubation, minor, major and very major error rates were 1.6% (n = 21), 0.2% (n = 1) and 0.7% (n = 4), respectively. The results of this study clearly indicate that early reading of inhibition zones to 10 h after incubation is feasible and accurate and thus may save significantly on turnaround time.

Routine identification of microorganisms by matrix-assisted laser desorption ionization time-of-flight mass spectrometry: Success rate, economic analysis, and clinical outcome

BACKGROUND

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been widely used in microbial identification. This study evaluated the performance of MALDI-TOF MS and investigated the economic and medical impact of MALDI-TOF MS implementation.

METHODS

A total of 12,202 clinical isolates collected from April to September 2013 were identified using MALDI-TOF MS, and the success rates in identifying isolates were analyzed. The differences in the processing time, cost of consumables, weight of waste, and clinical impact between MALDI-TOF MS and biochemical reaction were compared.

RESULTS

MALDI-TOF MS successfully identified 96% of 12,202 isolates, including 96.8% of 10,502 aerobes, 90.5% of 1481 anaerobes, 93.8% of 81 yeasts, and 90.6% of 138 nontuberculous mycobacteria at the genus level. By using MALDI-TOF MS, the processing time for aerobes decreased from 32.5 hours to 4.1 hours, and that for anaerobes decreased from 71.5 hours to 46 hours. For detection of aerobes and anaerobes, the cost of consumables was estimated to decrease by US$0.9 per isolate, thus saving US$94,500 in total annual isolation. Furthermore, the weight of waste decreased six-fold, resulting in a reduction of 350 kg/month or 4.2 tons/year. MALDI-TOF MS also increased the percentage of correct antibiotics treatment for Escherichia coli and Klebsiella pneumonia from 56.1% to 75% and shortened the initiation time of the correct antibiotic action from 3.3 hours to 2.5 hours.

CONCLUSIONS

MALDI-TOF MS is a rapid, reliable, economical, and environmentally friendly method for routine microbial identification and may contribute to early appropriate antibiotic treatment in clinical settings.

Clinical Impact of MALDI-TOF MS Identification and Rapid Susceptibility Testing on Adequate Antimicrobial Treatment in Sepsis with Positive Blood Cultures

Shortening the turn-around time (TAT) of positive blood culture (BC) identification (ID) and susceptibility results is essential to optimize antimicrobial treatment in patients with sepsis. We aimed to evaluate the impact on antimicrobial prescription of a modified workflow of positive BCs providing ID and partial susceptibility results for Enterobacteriaceae (EB), Pseudomonas aeruginosa and Staphylococcus aureus on the day of BC positivity detection. This study was divided into a pre-intervention period (P0) with a standard BC workflow followed by 2 intervention periods (P1, P2) with an identical modified workflow. ID was performed with MALDI-TOF MS from blood, on early or on overnight subcultures. According to ID results, rapid phenotypic assays were realized to detect third generation cephalosporin resistant EB/P. aeruginosa or methicillin resistant S. aureus. Results were transmitted to the antimicrobial stewardship team for patient's treatment revision. Times to ID, to susceptibility results and to optimal antimicrobial treatment (OAT) were compared across the three study periods. Overall, 134, 112 and 154 positive BC episodes in P0, P1 and P2 respectively were included in the analysis. Mean time to ID (28.3 hours in P0) was reduced by 65.3% in P1 (10.2 hours) and 61.8% in P2 (10.8 hours). Mean time to complete susceptibility results was reduced by 27.5% in P1 and 27% in P2, with results obtained after 32.4 and 32.6 hours compared to 44.7 hours in P0. Rapid tests allowed partial susceptibility results to be obtained after a mean time of 11.8 hours in P1 and 11.7 hours in P2. Mean time to OAT was decreased to 21.6 hours in P1 and to 17.9 hours in P2 compared to 36.1 hours in P0. Reducing TAT of positive BC with MALDI-TOF MS ID and rapid susceptibility testing accelerated prescription of targeted antimicrobial treatment thereby potentially improving the patients' clinical outcome.

Pathogen Prevalence and Antimicrobial Susceptibility Among Enterobacteriaceae Causing Hospital-associated Intra-abdominal Infections in Adults in the United States (2012-2013)

PURPOSE

Selection and prompt initiation of the appropriate empiric antimicrobial therapy are critical to decrease morbidity and mortality and shorten the length of hospitalization among patients with hospital-associated intra-abdominal infections (HA-IAIs). Therapeutic choices for the treatment of patients with HA-IAI require careful consideration. This study was conducted to evaluate the antimicrobial susceptibility of common pathogens collected from adult patients with HA-IAI in the United States.

METHODS

Gram-negative bacilli (N = 1285) were collected during 2012-2013 from SMART (Study for Monitoring Antimicrobial Resistance Trends). Isolates were tested at a central laboratory by using Clinical and Laboratory Standards Institute methods and interpretation of susceptibility to 12 antimicrobial agents.

FINDINGS

Most of the isolates (80.8%) were Enterobacteriaceae, and Escherichia coli was the most common species. Susceptibility to frequently used antimicrobial agents for treating IAI showed that ertapenem, imipenem, and amikacin were more active than other agents against Enterobacteriaceae, including multidrug-resistant isolates. More than 92% of E coli, including extended-spectrum β-lactamase (ESBL) producers, and Klebsiella pneumoniae isolates were susceptible to ertapenem, imipenem, and amikacin. Cefepime was the most active (>90% susceptibility) cephalosporin against all species except K pneumoniae (86.6%) but with much reduced activity against isolates with ESBLs. Piperacillin/tazobactam had reduced activity against Enterobacter species (70.4%-76.4% susceptible) and ESBL-producing K pneumoniae (22.5% susceptible). Fluoroquinolones exhibited poor activity against E coli (overall susceptibility <70%).

IMPLICATIONS

Proper empiric antimicrobial treatment, including combining appropriate agents, of HA-IAI requires detailed understanding of the epidemiology of common pathogens and antimicrobial resistance patterns. In light of rising rates of antimicrobial resistance, ongoing surveillance is critical for clinical decision-making.

Usage Pattern and Serum Level Measurement of Amikacin in the Internal Medicine Ward of the Largest Referral Hospital in the South of Iran: A Pharmacoepidemiological Study

BACKGROUND

The inappropriate use of aminoglycosides has harmful effects such as the development of resistant pathogens and the incidence of nephrotoxicity and ototoxicity. Therefore, drug utilization evaluation of these drugs may improve their usage remarkably. The aim of this study was to assess the usage pattern of amikacin in an internal medicine ward.

METHODS

This cross-sectional study was conducted in the Internal Medicine Ward of Nemazee Teaching Hospital, Shiraz, Iran, in 2011. The guideline for amikacin use was approved by the institutional Pharmacy and Therapeutics Committee, and the study criteria were developed to assess several parameters involved in amikacin therapy such as appropriateness of drug use, dosage, duration of therapy, toxicity monitoring, and serum concentration assay. Serum concentration was assayed using a Cobas Mira AutoAnalyzer. Clinical and paraclinical parameters such as glomerular filtration rate, culture, microbial sensitivity, white blood cell count, and fever were collected.

RESULTS

Sixty-three patients were evaluated. Fifty-seven percent of the patients needed dose readjustment; however, it was not performed for 89% of them. Culture between 48 and 72 hours after amikacin administration was not controlled for 79% of the patients. In 19% of the patients, optimum therapeutic effect was not achieved. The mean±SD of the trough and peak concentrations was 7.63±5.4 μg/mL and 15.67±7.79 μg/mL, respectively. Forty-five percent of the trough and 38% of the peak levels were within the therapeutic range. The overall adherence of amikacin usage to the guideline was only 48%.

CONCLUSION

To achieve appropriate treatment and prevent toxic effects, we recommend that pharmacokinetic dosing methods, amikacin guideline, and serum monitoring be considered.

Bloodstream infections in internal medicine

Bloodstream infections (BSI) carry a heavy burden of morbidity and mortality in modern internal medicine wards (IMW). These wards are often filled with elderly subjects with several risk factors for BSI, such as multiple comorbidities, polypharmacy, immunosuppression, and indwelling devices. Diagnosing BSI in such a setting might require a high degree of suspicion, since the clinical presentation could be affected by underlying conditions and concomitant medications, which might delay the administration of an appropriate antimicrobial therapy, an event strongly and unfavorably influencing survival. Furthermore, selecting the appropriate antimicrobial therapy to treat these patients is becoming an increasingly complex task in which all possible benefits and costs should be carefully analyzed from patient and public health perspectives. Only a specialized, continuous, and interdisciplinary approach could really improve the management of IMW patients in an era of increasing antimicrobial resistance and complexity of care.

Does it Matter if we get it right? Impact of appropriateness of empiric antimicrobial therapy among surgical patients

Previous studies have shown conflicting evidence regarding the impact of inappropriate, initial antibiotic therapy. The purpose of this study was to evaluate the impact of inappropriate empiric antimicrobial therapy for the treatment of infection among surgical patients. We hypothesized that inappropriate empiric antimicrobial therapy would predict increased mortality risk compared with appropriate therapy. This was a retrospective analysis of a prospectively maintained database of all surgical patients admitted to a tertiary care center from 1996 to 2007 and treated for sepsis. "Appropriate" empiric antibiotic treatment was determined by sensitivity testing. Demographics and comorbidities, infection sites, infection organisms, and outcomes were compared between inappropriately and appropriately treated groups. Multivariable log-binomial regression was performed. There were 2,855 patients (7,158 infectious episodes) identified by culture analysis as either appropriately or inappropriately treated. Three hundred seventeen (15%) inappropriately treated infectious episodes resulted in death compared with 718 (14%) of the appropriately treated infectious episodes. After adjusting for statistically significant variables, inappropriately treated episodes of infection were not found to be associated with an increased risk for mortality compared with appropriately treated episodes of infection (relative risk, 1.0; 95% confidence interval, 0.99 - 1.02; P = 0.36). Our study observed no difference in mortality between appropriately and inappropriately treated infections within a surgical population.

Rapid antimicrobial susceptibility testing of clinical isolates by digital time-lapse microscopy

Rapid antimicrobial susceptibility testing (AST) is essential for early and appropriate therapy. Methods with short detection time enabling same-day treatment optimisation are highly favourable. In this study, we evaluated the potential of a digital time-lapse microscope system, the oCelloScope system, to perform rapid AST. The oCelloScope system demonstrated a very high accuracy (96 % overall agreement) when determining the resistance profiles of four reference strains, nine clinical isolates, including multi-drug-resistant isolates, and three positive blood cultures. AST of clinical isolates (168 antimicrobial agent–organism combinations) demonstrated 3.6 % minor, no major and 1.2 % very major errors of the oCelloScope system compared to conventional susceptibility testing, as well as a rapid and correct phenotypic detection of strains with methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL) profiles. The net average time-to-result was 108 min, with 95 % of the results being available within 180 min. In conclusion, this study strongly indicates that the oCelloScope system holds considerable potential as an accurate and sensitive AST method with short time-to-result, enabling same-day targeted antimicrobial therapy, facilitating antibiotic stewardship and better patient management. A full-scale validation of the oCelloScope system including more isolates is necessary to assess the impact of using it for AST.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) directly from positive blood culture flasks allows rapid identification of bloodstream infections in immunosuppressed hosts

INTRODUCTION

In immunosuppressed hosts, rapid identification of microorganisms of bloodstream infections is crucial to ensuring effective antimicrobial therapy. Conventional culture requires up to 72 h from sample collection to pathogen identification.

METHODS

We used the SepsiTyper Kit and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF; Microflex, Bruker) directly from positive blood culture (BacT/ALERT 3D, FN/FA vials; bioMérieux) in comparison to standard culture methodology (VITEK 2; bioMérieux) for species identification.

RESULTS

A total of 62 consecutive positive blood cultures from immunosuppressed patients (solid organ or hematopoietic transplant recipients, or with febrile neutropenia) were analyzed. Culture yielded gram-negative bacteria (GNB) in 27/62 (43.5%) and gram-positive (GPB) in 35/62 (56.5%) vials. For GNB, the predominant species identified by MALDI-TOF and confirmed by VITEK were Escherichia coli (16/16 correctly identified) and Enterobacter cloacae (4/4), with a sensitivity and specificity of 92.6% and 100%, respectively. For GPB, predominant species were Staphylococcus aureus (3/3), coagulase-negative staphylococci (12/24), and Enterococcus faecium (6/6) with a sensitivity of 100%, 60%, and 100%, respectively. The median time from blood collection to species identification was 27.4 h with MALDI-TOF identification and 46.6 h with conventional methodology.

CONCLUSION

Using MALDI-TOF directly from positive blood cultures allowed a shorter time to identification with high sensitivity and specificity in immunosuppressed patients.

Description and validation of a spectrum score method to measure antimicrobial de-escalation in healthcare associated pneumonia from electronic medical records data

BACKGROUND

Comparison of antimicrobial de-escalation rates between healthcare settings is problematic. To objectively and electronically measure de-escalation a method based upon the spectrum of antimicrobial regimens administered (i.e., spectrum score) was developed.

METHODS

A Delphi process was used to develop applicable concepts. Spectrum scores were created for 27 antimicrobials based upon susceptibility for 19 organisms. National VA susceptibility data was used to estimate microbial spectrum. Susceptibility estimates were converted to ordinal scores, and values for organisms with multi-drug resistance potential were weighted more heavily. Organism scores were summed to create antibiotic-specific spectrum scores and extended mathematically to score multi-antimicrobial regimens. Vignettes were created from antimicrobial regimens administered to 300 patients hospitalized with pneumonia. Daily spectrum scores were calculated for each case. Hospitalization day 4 scores were subtracted from day 2 scores (i.e., spectrum score ∆). A positive spectrum score ∆ defined de-escalation. Experts ranked each pneumonia case on a 7-point Likert scale (Likert >4 indicated de-escalation). Spectrum score ∆s were compared to expert review. Findings were used to identify score deficiencies. Next, 40 pairs of cases were modified to include antimicrobial administration routes. Each pair contained almost similar regimens; however, one contained oral (PO) the other only intravenous (IV) antimicrobials on day 4 of therapy. Experts reviewed cases as described. Spectrum score ∆ credits to account for PO conversion were derived from the mean paired differences in Likert Score. De-escalation status was evaluated in 100 vignettes containing antimicrobial route by different experts and compared to the modified method.

RESULTS

Initial sensitivity and specificity of the spectrum score ∆ to detect expert classified de-escalation events was 86.3 and 96.0%, respectively. In paired cases, the mean (± SD) Likert score was 5.0 (1.5) and 4.6 (1.5) for PO and IV (P = 0.002), respectively. To improve de-escalation event detection, two credits were added to spectrum score ∆s based upon the percentage of antimicrobials administered PO on day 4. The final method, exhibited sensitivity and specificity to detect expert classified de-escalation events of 96.2 and 93.6%, respectively.

CONCLUSIONS

The final spectrum score method exhibited excellent agreement with expert judgments of de-escalation events in pneumonia.

Critical Care for the Patient With Multiple Trauma

Trauma remains the leading cause of death worldwide and the leading cause of death in those less than 44 years old in the United States. Admission to a verified trauma center has been shown to decrease mortality following a major injury. This decrease in mortality has been a direct result of improvements in the initial evaluation and resuscitation from injury as well as continued advances in critical care. As such, it is vital that intensive care practitioners be familiar with various types of injuries and their associated treatment strategies as well as their potential complications in order to minimize the morbidity and mortality frequently seen in this patient population.

Characteristics of surgical patients receiving inappropriate empiric antimicrobial therapy

BACKGROUND

Inappropriate antibiotics have been observed to result in an increased duration of antibiotic treatment and hospital length of stay, development of multidrug-resistant organisms, and mortality rate compared with appropriate antibiotic treatment. Few studies have evaluated independent risk factors associated with inappropriateness. The purpose of this study was to identify independent predictors of inappropriate, empiric antimicrobial therapy for the treatment of severe sepsis.

METHODS

This was a retrospective analysis of a prospectively maintained database of all surgical/trauma patients admitted to a tertiary care center from 1996 to 2007 and treated for sepsis. "Appropriate" empiric antibiotic treatment was determined by sensitivity testing. Demographics and comorbidities, infection sites, infection organisms, and outcomes between strata were compared. Differences in outcome were estimated using relative risk and 95% confidence intervals for correlated data.

RESULTS

A total of 2,855 patients (7,158 infections) were identified. Independent predictors of inappropriate, empiric antimicrobial therapy for the treatment of severe sepsis included site of infection and organism type. Severity of illness, age, medical conditions, and community versus health care-associated infections were not associated with inappropriate therapy. Although inappropriate empiric therapy was associated with a longer length of stay and duration of antimicrobial use, it did not result in higher mortality.

CONCLUSION

Our study observed that inappropriate empiric antibiotic selection is related to site of infection and pathogen. Other clinical variables do not appear to predict inappropriateness of antibiotic treatment. Efforts should be focused on early broad-spectrum therapy and more rapid microbiologic methods.

LEVEL OF EVIDENCE

Therapeutic/care management study, level II.

Rapid and fully automated bacterial pathogen detection on a centrifugal-microfluidic LabDisk using highly sensitive nested PCR with integrated sample preparation

Diagnosis of infectious diseases suffers from long turnaround times for gold standard culture-based identification of bacterial pathogens, therefore impeding timely specific antimicrobial treatment based on laboratory evidence. Rapid molecular diagnostics-based technologies enable detection of microorganisms within hours however cumbersome workflows and complex equipment still prevent their widespread use in the routine clinical microbiology setting. We developed a centrifugal-microfluidic "LabDisk" system for rapid and highly-sensitive pathogen detection on a point-of-care analyser. The unit-use LabDisk with pre-stored reagents features fully automated and integrated DNA extraction, consensus multiplex PCR pre-amplification and geometrically-multiplexed species-specific real-time PCR. Processing merely requires loading of the sample and DNA extraction reagents with minimal hands-on time of approximately 5 min. We demonstrate detection of as few as 3 colony-forming-units (cfu) of Staphylococcus warneri, 200 cfu of Streptococcus agalactiae, 5 cfu of Escherichia coli and 2 cfu of Haemophilus influenzae in a 200 μL serum sample. The turnaround time of the complete analysis from "sample-to-result" was 3 h and 45 min. The LabDisk consequently provides an easy-to-use molecular diagnostic platform for rapid and highly-sensitive detection of bacterial pathogens without requiring major hands-on time and complex laboratory instrumentation.

Safety and clinical outcomes of carbapenem de-escalation as part of an antimicrobial stewardship programme in an ESBL-endemic setting

OBJECTIVES

To evaluate the safety and clinical outcomes of patients who received carbapenem de-escalation as guided by an antimicrobial stewardship programme (ASP) in a setting where ESBL-producing Enterobacteriaceae are endemic.

METHODS

Patients receiving meropenem or imipenem underwent a prospective ASP review for eligibility for de-escalation according to defined institutional guidelines. Patients in whom carbapenem was de-escalated or not de-escalated, representing the acceptance and rejection of the ASP recommendation, respectively, were compared. The primary outcome was the clinical success rate; secondary outcomes included the 30 day readmission and mortality rates, the duration of carbapenem therapy, the incidence of adverse drug reactions due to antimicrobials, the acquisition of carbapenem-resistant Gram-negative bacteria and the occurrence of Clostridium difficile-associated diarrhoea (CDAD).

RESULTS

The de-escalation recommendations for 300 patients were evaluated; 204 (68.0%) were accepted. The patient demographics and disease severity were similar. The clinical success rates were similar [de-escalated versus not de-escalated, 183/204 (89.7%) versus 85/96 (88.5%), P=0.84], as was the survival at hospital discharge [173/204 (84.8%) versus 79/96 (82.3%), P=0.58]. In the de-escalated group, the duration of carbapenem therapy was shorter (6 versus 8 days, P<0.001), the rate of adverse drug reactions was lower [11/204 (5.4%) versus 12/96 (12.5%), P=0.037], there was less diarrhoea [9/204 (4.4%) versus 12/96 (12.5%), P=0.015], there was a lower incidence of carbapenem-resistant Acinetobacter baumannii acquisition [4/204 (2.0%) versus 7/96 (7.3%), P=0.042] and there was a lower incidence of CDAD [2/204 (1.0%) versus 4/96 (4.2%), P=0.081].

CONCLUSIONS

This study suggests that the ASP-guided de-escalation of carbapenems led to comparable clinical success, fewer adverse effects and a lower incidence of the development of resistance. This approach is safe and practicable, and should be a key component of an ASP.

What should be considered in the treatment of bacterial infections by multi-drug therapies: a mathematical perspective?

Bacterial infections are a global health concern with high levels of mortality and morbidity associated. The resistance of pathogens to drugs is one leading cause of this problem, being common the administration of multiple drugs to improve the therapeutic effects. This review critically explores diverse aspects involved in the treatment of bacterial infections through multi-drug therapies, from a mathematical and within-host perspectives. Five recent models were selected and are reviewed. These models fall into the following question: which drugs to select, the respective dose, the administration period to effectively eradicate the infection in the shortest period of time and with reduced side effects? In this analysis, three groups of variables were considered: pharmacokinetics, pharmacodynamics and disturbance variables. To date, there is no model that fully answers to this issue for a living organism and it is questionable whether this would be possible for any case of infection.

Fever and the rational use of antimicrobials in the emergency department

Any patient presenting to the emergency department (ED) with fever triggers consideration of the administration of an antimicrobial. Empiric antimicrobial therapy has become a cornerstone of treatment. Frequently, the decision to initiate empiric treatment needs to be made before the definitive diagnosis is known. In such cases, an organized approach is helpful. This article aims to provide a systems-based approach to prescribing antimicrobials to patients presenting to the ED with fever, while understanding the risk associated with overutilization. An understanding of the key considerations is needed to ensure that decisions are made well and appropriate treatment begins promptly.

Locally derived versus guideline-based approach to treatment of hospital-acquired pneumonia in the trauma intensive care unit

BACKGROUND

Appropriate initial antibiotic therapy for presumed pneumonia in critically ill patients decreases the mortality rate. To achieve this goal, treatment guidelines developed by groups such as the American Thoracic Society (ATS) have been stressed. However, often overlooked is the importance of incorporating local microbiologic data into an empiric algorithm. Our hypothesis was that an empiric algorithm supported by our locally-driven analysis would predict more accurate coverage than one defined strictly by an unmodified guideline-driven approach.

METHODS

Retrospective review of all first hospital-acquired (HAP) and ventilator-associated pneumonia (VAP) pathogens in consecutive trauma intensive care unit (TICU) patients over 18 months. Microbiologic data were analyzed to update our TICU-specific empiric algorithm. The ATS guidelines define patients at risk for multidrug-resistant (MDR) organisms on the basis of standardized criteria and time since admission (early <5 days; late ≥5 days).

RESULTS

A total of 164 pathogens caused 117 pneumonias. For early coverage, ATS guidelines stress identification of MDR risks; these criteria failed to identify 8 of 13 (62%) early MDR pneumonias. For early HAP/VAP with no MDR risks, the ATS guidelines recommend monotherapy; susceptibility differed (49% to ciprofloxacin, 68% to ampicillin-sulbactam, 83% to ceftriaxone). A total of 15% of early pathogens were MDR gram-positive, so addition of vancomycin resulted in adequate predicted coverage of 100%, 79%, and 95% for ciprofloxacin, ampicillin-sulbactam, and ceftriaxone, respectively. For late HAP/VAP, ATS recommends regimens based on broad-spectrum drugs. Vancomycin with ciprofloxacin, cefepime, or piperacillin-tazobactam had predicted coverage of 95%, 94%, and 93%, respectively.

CONCLUSIONS

The empiric algorithm derived from analysis of local microbiologic data predicted significantly better coverage than one defined by an unmodified guideline-driven approach for early HAP/VAP. Our locally-derived TICU algorithm of ceftriaxone+vancomycin for early pneumonia and piperacillin-tazobactam+vancomycin for late pneumonia optimizes the adequacy of initial therapy. Understanding local patterns of pneumonia ensures the creation and maintenance of empiric algorithms that achieve the best clinical outcomes.