Appropriate use of antimicrobial agents: challenges and strategies for improvement

Population pharmacokinetic analysis and dosing regimen optimization of teicoplanin in critically ill patients with sepsis

Objectives: Teicoplanin has been extensively used in the treatment for infections caused by gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). However, current teicoplanin treatment is challenging due to relatively low and variable concentrations under standard dosage regimens. This study aimed to investigate the population pharmacokinetics (PPK) characteristics of teicoplanin in adult sepsis patients and provide recommendations for optimal teicoplanin dosing regimens. Methods: A total of 249 serum concentration samples from 59 septic patients were prospectively collected in the intensive care unit (ICU). Teicoplanin concentrations were detected, and patients' clinical data were recorded. PPK analysis was performed using a non-linear, mixed-effect modeling approach. Monte Carlo simulations were performed to evaluate currently recommended dosing and other dosage regimens. The optimal dosing regimens were defined and compared by different pharmacokinetic/pharmacodynamic parameters, including trough concentration (C_min), the ratio of 24-h area under the concentration-time curve to the minimum inhibitory concentration (AUC_0-24/MIC), as well as the probability of target attainment (PTA) and the cumulative fraction of response (CFR) against MRSA. Results: A two-compartment model adequately described the data. The final model parameter estimates for clearance, central compartment volume of distribution, intercompartmental clearance and peripheral compartment volume were 1.03 L/h, 20.1 L, 3.12 L/h and 101 L, respectively. Glomerular filtration rate (GFR) was the only covariate that significantly affected teicoplanin clearance. Model-based simulations revealed that 3 or 5 loading doses of 12/15 mg/kg every 12 h followed by a maintenance dose of 12/15 mg/kg every 24 h-72 h for patients with different renal functions were required to achieve a target C_min of 15 mg/L and a target AUC_0-24/MIC of 610. For MRSA infections, PTAs and CFRs were not satisfactory for simulated regimens. Prolonging the dosing interval may be easier to achieve the target AUC_0-24/MIC than reducing the unit dose for renal insufficient patients. Conclusion: A PPK model for teicoplanin in adult septic patients was successfully developed. Model-based simulations revealed that current standard doses may result in undertherapeutic C_min and AUC, and a single dose of at least 12 mg/kg may be needed. AUC_0-24/MIC should be preferred as the PK/PD indicator of teicoplanin, if AUC estimation is unavailable, in addition to routine detection of teicoplanin C_min on Day 4, follow-up therapeutic drug monitoring at steady-state is recommended.

Optimizing antimicrobial therapy in urinary tract infections: A focus on urine culture and sensitivity testing

Objectives: This cross-sectional study was conducted at Jordan university hospital to evaluate the impact of microbial culture data and sensitivity results on optimizing UTI treatment. Methods: All positive urine cultures requested for adult patients (≥18 years) admitted to Jordan University Hospital (JUH) within the period from January 2019-July 2021 were evaluated. The antibiotics prescribed before and after culture data and sensitivity results were compared to evaluate the impact of these diagnostic measures on optimizing UTI treatment. Results: During the study period, 2400 urine cultures revealed positive results. Among those patients, 1,600 (66.7%) were discharged before the availability of culture results and excluded. Of the remaining 800 patients, 701 patients (87.6%) received empiric treatment. After culture and sensitivity results were available, overall, 84 (10.5%) patients had optimization (improvement) in their UTI management after culture results were known, while 6 (0.8%) patients had a worsening in their treatments. Based on the culture results, we found that only 12.4% of patients were appropriately treated before and after the culture results. Moreover, our results revealed that 31.9% were inappropriately treated for their UTIs before and after culture results. Conclusion: This study revealed an alarmingly high rate of inappropriate treatment of UTIs despite the availability of urine culture and sensitivity data, and that culture results were not used to optimize treatment strategies for UTI. This practice can potentially result in poor health-related outcomes and adversely affects efforts to battle AMR. Multifaceted strategies must be implemented to help clinicians follow the best current evidence and current guidelines in their selection of antibiotics for the management of UTIs.

Financial strategies targeting healthcare providers to promote the prudent use of antibiotics: a systematic review of the evidence

Improving prudent use of antibiotics is one way to limit the spread of antimicrobial resistance (AMR). The objective of this systematic review was to assess the effects of financial strategies targeting healthcare providers on the prudent use of antibiotics. A systematic review of the literature was conducted searching PubMed, Embase and Cochrane databases, and the grey literature. Search terms related to antibacterial agents, drug resistance, financial strategies, and healthcare providers and/or prescribers. Twenty-two articles were included in the review, reporting on capitation and salary reimbursement, cost containment interventions, pay-for-performance initiatives, penalties, and a one-off bonus payment. There was substantial variation in the reported outcomes describing prescribing behaviours, including proportion of patients prescribed antibiotics, antibiotic prescriptions per patient, and number of cases treated with recommended antibiotic therapy. All financial strategies were associated with improvements in the appropriate prescription of antibiotics in the short-term, although the magnitude of observed effects varied across financial strategies. Financial penalties were associated with the greatest decreases in inappropriate antibiotic prescriptions, followed by capitation models and pay-for-performance schemes that paid bonuses upon achievement of performance targets. However, the risk of bias across studies must be noted. Findings point to the viability of financial strategies to promote the prudent use of antibiotics. Measuring the downstream impact of prescriber behaviour changes is key to estimating the true value of such interventions to tackle AMR. Research efforts should continue to build the evidence on causal mechanisms driving provider prescribing patterns for antibiotics and the long-term impact on antibiotic prescriptions.

Antibiotics or No Antibiotics, That Is the Question: An Update on Efficient and Effective Use of Antibiotics in Dental Practice

The antimicrobial resistance (AMR) phenomenon is an emerging global problem and is induced by overuse and misuse of antibiotics in medical practice. In total, 10% of antibiotic prescriptions are from dentists, usually to manage oro-dental pains and avoid postsurgical complications. Recent research and clinical evaluations highlight new therapeutical approaches with a reduction in dosages and number of antibiotic prescriptions and recommend focusing on an accurate diagnosis and improvement of oral health before dental treatments and in patients’ daily lives. In this article, the most common clinical and operative situations in dental practice, such as endodontics, management of acute alveolar abscesses, extractive oral surgery, parodontology and implantology, are recognized and summarized, suggesting possible guidelines to reduce antibiotic prescription and consumption, maintaining high success rates and low complications rates. Additionally, the categories of patients requiring antibiotic administration for pre-existing conditions are recapitulated. To reduce AMR threat, it is important to establish protocols for treatment with antibiotics, to be used only in specific situations. Recent reviews demonstrate that, in dentistry, it is possible to minimize the use of antibiotics, thoroughly assessing patient’s conditions and type of intervention, thus improving their efficacy and reducing the adverse effects and enhancing the modern concept of personalized medicine.

Evaluation of the appropriateness of meropenem prescribing at a tertiary care hospital: A retrospective study in Oman

OBJECTIVES

The aim of this study was to evaluate the use of meropenem in terms of indication and continuation of treatment at Sultan Qaboos University Hospital (SQUH), Muscat, Oman.

METHODS

A retrospective observational study, conducted by reviewing the medical records of 400 adults, admitted patients who received at least one dose of meropenem during the study period (January 2017 to September 2017). The analysis was performed using univariate statistics.

RESULTS

Meropenem was prescribed empirically in 382/400 (96%) of the cases. The majority (315/361 (87%)) of the patients received the proper meropenem dose. The indication for meropenem was considered appropriate in only 196/400 (49%) of the cases. The continuation of treatment was evaluated according to culture and sensitivity results in 202 cases, out of which 112 (55%) were justified. Most of the inappropriate uses were seen in oncology and hematology cases (31/42 (74%) and 61/101 (60%), respectively) and among respiratory and urinary tract infections (126/155 (81%) and 40/46 (87%), respectively).

CONCLUSIONS

Approximately half of the meropenem orders at SQUH in Oman were inappropriate and unjustified by culture-test results. New strategies are needed to optimize the rational use of meropenem and to ensure appropriate de-escalation and discontinuation of meropenem whenever indicated.

Evaluation of an outpatient department (OPD)-based prescribing pattern of fixed-dose combinations in a tertiary care institute in Central India

Background Fixed-dose combinations (FDCs) are being widely prescribed for the treatment of various disorders in India. However, not all FDCs are rational. To know the awareness of physicians in prescribing rational FDCs was the need of the hour in order to assess the prescribing trends and rationality of FDCs. Eventually, this will help to formulate the guideline for rational use of FDCs. Methods This was a prospective observational study conducted in All India Institute of Medical Sciences Bhopal, MP, India. Prescriptions were collected over a period of 2 months by the convenience sampling method from hospital pharmacy. The data were subjected to descriptive analysis using Microsoft Excel and Graph Pad Prism. Results were expressed in mean ± standard deviation (SD), percentages and 95% confidence interval. Results A total of 2496 drugs were prescribed in 1008 prescriptions, of which 945 (37.82%) were FDCs with an average of 0.93 ± 0.94 (mean ± SD) per prescription. Of 945, 67 (7.09%) were included in National List of Essential Medicine 2015 considered as rational. The number of prescriptions containing one or more FDCs was 629 (62.40%). FDCs were more frequently prescribed to male patients (54.92%) and in the age group of 18-30 years (33.44%). FDCs containing a proton pump inhibitor were prescribed most frequently (16.29%) followed by nonsteroidal anti-inflammatory drugs (13.96%) and multivitamins (7.83%). Conclusions Prescribing irrational FDCs was very common, and hence there is an obvious need to update our prescribers about the irrationality of FDC and motivate them to develop a habit of rational prescribing.

A Prospective Antibacterial Utilization Study in Pediatric Intensive Care Unit of a Tertiary Referral Center

Purpose:

Antibacterials are commonly prescribed to Pediatric Intensive Care Unit (PICU) patients. However, inappropriate antibacterial prescriptions lead to increases in antibacterial resistance, treatment cost, duration of treatment, and poor clinical outcome. The antibacterial utilization study assesses the prescription patterns and if necessary recommends the interventions to improve antibacterial prescriptions. Hence, the present prospective groundwork was conducted.

Materials and Methods:

The study was conducted over the period of 6 months (April 18 to October 20, 2014). The demographics and drug use details were captured daily from patients admitted to PICU to assess World Health Organization indicators.

Results:

A total of 200 patients enrolled, among them 119 males and 81 females. There were 12.46 (±6.16) drugs prescribed per patient, of which 2.38 (±1.48) were antibacterials. Among the total drug prescribed, 18.49% were antibacterials and 97% patients received at least one antibacterial. Ceftriaxone (49.48%) was the most commonly prescribed antibacterial, while imipenem (2.58%) and colistin (2.06%) use was very low. A total of 80.95% antibacterials were prescribed by generic name, 94.88% were administered intravenously, and 80.76% were prescribed from hospital pharmacy. The average length of PICU stay was 6.15 days (±6.20), the average length of antibacterial treatment was 6.08 days (±6.27), and the average length of empirical antibacterial treatment was 5.50 days (±5.40). The cost of antibacterial therapy per patient was Indian rupees 824.64 (±235.35). In 27 patients, bacterial culture test was positive and of whom 21 received antibacterials as per sensitivity pattern.

Conclusions:

The use of antibacterials was not indiscriminately high but more prescriptions per sensitivity pattern are required.

Impact of Antibiotic Stewardship Program on Prescribing Pattern of Antimicrobials in Patients of Medical Intensive Care Unit

INTRODUCTION

Rising concerns about antimicrobial resistance and inadequate development of effective new anti-infective drugs have stimulated universal efforts to strengthen infection-control interventions. Antimicrobial stewardship is a rational, systematic approach to promote the optimal selection, dosing, and duration of therapy for antimicrobial agents throughout the course of their use in order to improve the outcomes.

AIM

Since in Shree Krishna Hospital (SKH), Antibiotic Stewardship Program (ASP) was first implemented in 2013, this study was planned to assess any change in antimicrobial use before and after implementation of ASP and to study the rate and pattern of antimicrobial use in medical ICU.

MATERIALS AND METHODS

A cross-sectional study was conducted in 12 bedded medical intensive care unit, over a period of two years from October 2014 to October 2016 at SKH. Permission was taken from Institutional Human Research Ethics Committee. Total 150 case files i.e., 75 from year 2012 and 75 from year 2015 were retrieved from medical record section of the hospital. Appropriateness of prescriptions was decided on the basis of appropriateness of choice, dose, frequency and duration of antimicrobial agents. Data were analysed by using descriptive statistics.

RESULTS

There were 68.67% males and the mean (±SD) age was 57.11 (±16.83) years. Majority of the patients were suffering from respiratory conditions. The most common group of drugs prescribed in MICU was β-lactam antibiotics + β-lactamase inhibitors during 2012 as well as 2015. Total 139 patients i.e., 69 (92%) patients in 2012 and 70 (93.33%) patients in 2015 were given antimicrobial for therapeutic purpose. During the year 2015, 67 (89.33%) antimicrobial prescriptions were adhering to antibiotic policy of SKH. Appropriateness of prescriptions had significantly improved in 2015 in MICU (p-value=0.031).

CONCLUSION

In-depth analysis of the study revealed a positive impact of ASP and antibiotic policy. Implementation of ASP in year 2013, brought an effective increase in the appropriate use of antimicrobials.

Strategies to avoid treatment-induced lineage crisis in advanced prostate cancer

The increasing potency of therapies that target the androgen receptor (AR) signalling axis has correlated with a rise in the proportion of patients with prostate cancer harbouring an adaptive phenotype, termed treatment-induced lineage crisis. This phenotype is characterized by features that include soft-tissue metastasis and/or resistance to standard anticancer therapies. Potent anticancer treatments might force cancer cells to evolve and develop alternative cell lineages that are resistant to primary therapies, a mechanism similar to the generation of multidrug- resistant microorganisms after continued antibiotic use. Herein, we assess the hypothesis that treatment-adapted phenotypes harbour reduced AR expression and/or activity, and acquire compensatory strategies for cell survival. We highlight the striking similarities between castration-resistant prostate cancer and triple-negative breast cancer, another poorly differentiated endocrine malignancy. Alternative treatment paradigms are needed to avoid therapy-induced resistance. Herein, we present a new clinical trial strategy designed to evaluate the potential of rapid drug cycling as an approach to delay the onset of resistance and treatment-induced lineage crisis in patients with metastatic castration-resistant prostate cancer.

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.

Antibiotic prescription and cost patterns in a general intensive care unit

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

Methods

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

Results

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

Conclusions

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

Implementation of a computerized decision support system to improve the appropriateness of antibiotic therapy using local microbiologic data

A prospective quasi-experimental study was undertaken in 218 patients with suspicion of nosocomial infection hospitalized in a polyvalent ICU where a new electronic device (GERB) has been designed for antibiotic prescriptions. Two GERB-based applications were developed to provide local resistance maps (LRMs) and preliminary microbiological reports with therapeutic recommendation (PMRTRs). Both applications used the data in the Laboratory Information System of the Microbiology Department to report on the optimal empiric therapeutic option, based on the most likely susceptibility profile of the microorganisms potentially responsible for infection in patients and taking into account the local epidemiology of the hospital department/unit. LRMs were used for antibiotic prescription in 20.2% of the patients and PMRTRs in 78.2%, and active antibiotics against the finally identified bacteria were prescribed in 80.0% of the former group and 82.4% of the latter. When neither LMRs nor PMRTRs were considered for empiric treatment prescription, only around 40% of the antibiotics prescribed were active. Hence, the percentage appropriateness of the empiric antibiotic treatments was significantly higher when LRM or PMRTR guidelines were followed rather than other criteria. LRMs and PMRTRs applications are dynamic, highly accessible, and readily interpreted instruments that contribute to the appropriateness of empiric antibiotic treatments.

Use of collateral sensitivity networks to design drug cycling protocols that avoid resistance development

New drug deployment strategies are imperative to address the problem of drug resistance, which is limiting the management of infectious diseases and cancers. We evolved resistance in Escherichia coli toward 23 drugs used clinically for treating bacterial infections and mapped the resulting collateral sensitivity and resistance profiles, revealing a complex collateral sensitivity network. On the basis of these data, we propose a new treatment framework--collateral sensitivity cycling--in which drugs with compatible collateral sensitivity profiles are used sequentially to treat infection and select against drug resistance development. We identified hundreds of such drug sets and demonstrated that the antibiotics gentamicin and cefuroxime can be deployed cyclically such that the treatment regimen selected against resistance to either drug. We then validated our findings with related bacterial pathogens. These results provide proof of principle for collateral sensitivity cycling as a sustainable treatment paradigm that may be generally applicable to infectious diseases and cancer.

Quantitative analysis and pharmacokinetics study of tigecycline in human serum using a validated sensitive liquid chromatography with tandem mass spectrometry method

Tigecycline, a novel intravenously administered glycylcycline antibiotic, currently plays a key role in the management of complicated multiorganism infections. However, current liquid chromatography with tandem mass spectrometry methods briefly describe parameters and the only reported internal standard was sometimes difficult to obtain. In our study, an updated liquid chromatography with tandem mass spectrometry method for the quantitative analysis of tigecycline in human serum was developed. Sample preparation involved precipitation with 20% trichloroacetic acid. Chromatographic separation of tigecycline and tetracycline (internal standard) was achieved on a Hypersil GOLD C18 column using gradient elution. The selected reaction monitoring transitions were performed at m/z 586.1→513.2 for tigecycline and m/z 445.1→410.2 for tetracycline. The assay was linear over the concentration range of 5-2000 ng/mL. The intra- and interday precisions at three concentration levels (10, 100, and 1600 ng/mL) were <15% and their accuracies were within the range of 95.1-106.1%. The mean recovery ranged from 94.3 to 105.6% and the matrix effect from 92.1 to 97.6%. Tigecycline was stable under all tested conditions. This validated method was successfully applied to a pharmacokinetic study in critically ill patients. The data demonstrated that our method allows quantification of tigecycline in serum in a quick and reliable manner for widespread application.

[Tarragona strategy--appropriate antibiotic therapy in the ICU]

BACKGROUND

Appropriate antibiotic initial therapy remarkably decreases the mortality of patients with infections in the ICU. The establishment of an appropriate initial therapy follows empirical aspects. This practice was first done for the treatment of nosocomial pneumonia. Since that time the practice became known as Tarragona strategy.

RESULTS

The basic elements of the strategy are based on the initial antibiotic treatment of patients with infections in the ICU in general and include the following: view the patient and his/her medical history, consider the microbiologic environment, in which the patient became ill, test for possible causative microorganisms and initiate high-dose antibiotics immediately, evaluate pharmacokinetic/pharmacodynamic aspects influenced by the pathophysiologic processes in the critically ill patient, the specifics of the microorganisms, the peculiarity of the antibiotics in the patient and due to therapeutic procedures, and tailor the initial broad spectrum therapy as necessary according to the microbiological results.

CONCLUSION

This procedure is safe, reduces mortality, limits the development of resistance, and is economic.

Antibiotic resistance in the intensive care unit setting

Antibiotic resistance is an important factor influencing clinical outcome for patients in intensive care units. It is also associated with increased healthcare costs resulting from prolonged patient stays. The problem of antibiotic resistance is particularly acute in intensive care units because they house seriously ill patients who are predisposed to infection, as a result of which, antibiotic use is extremely common. Strategies for controlling resistance in intensive care units have focused on attempting to reduce unnecessary antibiotic use, while at the same time ensuring adequate antibiotic cover is provided. The formulation of policies for the effective use of antibiotics in individual intensive care units requires a multidisciplinary approach, entailing regular epidemiological surveillance, together with input from critical care specialists, infectious disease specialists and pharmacists.

A 9-Year retrospective review of antibiotic cycling in a surgical intensive care unit

BACKGROUND

Six years after initiating a monthly antibiotic cycling protocol in the surgical intensive care unit (SICU), we retrospectively reviewed antibiogram-derived sensitivities of predominant gram-negative pathogens before and after antibiotic cycling. We also examined susceptibility patterns in the medical intensive care unit (MICU) where antibiotic cycling is not practiced.

MATERIALS AND METHODS

Antibiotic cycling protocol was implemented in the SICU starting in 2003, with monthly rotation of piperacillin/tazobactam, imipenem/cilastin, and ceftazidime. SICU antibiogram data from positive clinical cultures for years 2000 and 2002 were included in the pre-cycling period, and those from 2004 to 2009 in the cycling period.

RESULTS

Profiles of SICU pseudomonal isolates before (n = 116) and after (n = 205) implementing antibiotic cycling showed statistically significant improvements in susceptibility to ceftazidime (66% versus 81%; P = 0.003) and piperacillin/tazobactam (75% versus 85%; P = 0.021), while susceptibility to imipenem remained unaltered (70% in each case; P = 0.989). Susceptibility of E. coli isolates to piperacillin/tazobactam improved significantly (46% versus 83%; P < 0.0005), trend analysis showing this improvement to persist over the study period (P = 0.025). Similar findings were not observed in the MICU. Review of 2004-2009 antibiotic prescription practices showed monthly heterogeneity in the SICU, and a 2-fold higher prescribing of piperacillin/tazobactam in the MICU (P < 0.0001).

CONCLUSIONS

Six years into antibiotic cycling, we found either steady or improved susceptibilities of clinically relevant gram-negative organisms in the SICU. How much of this effect is from cycling is unknown, but the antibiotic heterogeneity provided by this practice justifies its ongoing use.

Community-acquired polymicrobial pneumonia in the intensive care unit: aetiology and prognosis

INTRODUCTION

The frequency and clinical significance of polymicrobial aetiology in community-acquired pneumonia (CAP) patients admitted to the ICU have been poorly studied. The aim of the present study was to describe the prevalence, clinical characteristics and outcomes of severe CAP of polymicrobial aetiology in patients admitted to the ICU.

METHODS

The prospective observational study included 362 consecutive adult patients with CAP admitted to the ICU within 24 hours of presentation; 196 (54%) patients had an established aetiology.

RESULTS

Polymicrobial infection was present in 39 (11%) cases (20% of those with defined aetiology): 33 cases with two pathogens, and six cases with three pathogens. The most frequently identified pathogens in polymicrobial infections were Streptococcus pneumoniae (n = 28, 72%), respiratory viruses (n = 15, 39%) and Pseudomonas aeruginosa (n = 8, 21%). Chronic respiratory disease and acute respiratory distress syndrome criteria were independent predictors of polymicrobial aetiology. Inappropriate initial antimicrobial treatment was more frequent in the polymicrobial aetiology group compared with the monomicrobial aetiology group (39% vs. 10%, P < 0.001), and was an independent predictor of hospital mortality (adjusted odds ratio = 10.79, 95% confidence interval = 3.97 to 29.30; P < 0.001). The trend for higher hospital mortality of the polymicrobial aetiology group compared with the monomicrobial aetiology group (n = 8, 21% versus n = 17, 11%), however, was not significantly different (P = 0.10).

CONCLUSIONS

Polymicrobial pneumonia occurs frequently in patients admitted to the ICU. This is a risk factor for inappropriate initial antimicrobial treatment, which in turn independently predicts hospital mortality.

[Antibiotic multiresistance in critical care units]

The presence of microorganisms with acquired resistance to multiple antibiotics complicates the management and outcome of critically ill patients. The intensivist, in his/her daily activity, is responsible for the prevention and control of the multiresistance and the challenge of prescribing the appropriate treatment in case of an infection by these microorganisms. We have reviewed the literature regarding the definition, important concepts related to transmission, recommendations on general measures of control in the units and treatment options. We also present data on the situation in our country known primarily through the ENVIN-UCI register. Addressing the multiresistance not only requires training but also teamwork with other specialists and adaptation to the local environment.

Neonatal community-acquired pneumonia: pathogens and treatment

AIM

To analyse the bacterial pathogens and drug sensitivities for neonatal community-acquired pneumonia.

METHODS

Seven hundred sixty sputum samples from newborns with community-acquired pneumonia were cultured to determine microbial organisms present and their drug sensitivities.

RESULTS

Of the 760 specimens, 425 grew pathogens for a 55.9% positive rate. Among the 425 positive cultures, 278 grew gram-negative organisms (65.4%), 142 grew gram-positive organisms (33.3%), while 5 grew fungus (1.3%). The most common gram-negative organisms were Escherichia coli, Klebsiella pneumoniae and Hemophilus influenzae, while the most common gram-positive organisms were Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus haemolyticus. To the gram-negative organisms, the most sensitive drugs were meropenem, imipenem and amikacin, while to the gram-positive ones were vancomycin, teicoplanin and quinupristin/dalfopristin.

CONCLUSIONS

The most common causative bacteria were gram-negative organisms, which were highly sensitive to Meropenem, Imipenem and Amikacin, yet often treatable with more focused antibiotic coverage, which depended on the bacterium identified.

The safety of targeted antibiotic therapy for ventilator-associated pneumonia: a multicenter observational study

PURPOSE

The aim of this study was to determine the safety of targeted antibiotic therapy (TT) in ventilator-associated pneumonia (VAP).

MATERIALS AND METHODS

This was a secondary analysis from a multicenter trial of 740 patients with suspected VAP randomized to bronchoscopy or endotracheal aspirate cultures; all received empirical broad-spectrum antibiotics. Patients were grouped by whether they received TT, defined as tailoring or discontinuing antibiotics in response to enrolment culture results.

RESULTS

For patients with a positive culture (n = 412), baseline demographics, clinical progression of infection and multiple organ dysfunction scores (MODS), and mortality were similar for those on TT (n = 320) or those who did not receive TT (NoTT) (n = 92). The TT group had more days alive and off broad-spectrum antibiotics (14.5 vs 13.2, P = .04). In patients with a negative culture (n = 327), those on TT (n = 230) had similar baseline demographics, less frequent final adjudicated diagnosis of VAP (63.0% vs 76.3%, P = .02), and less severe clinical progression of infection and MODS compared with NoTT (n = 97). The TT group had more days alive and off broad-spectrum antibiotics (15.9 vs 13.1, P < .001), lower delta MODS (2.0 vs 3.0, P = .01), fewer mechanical ventilation days (9.8 vs 14.7, P = .03), and similar mortality compared to NoTT.

CONCLUSIONS

Targeted therapy is associated with less antibiotic use and no evidence of harm in the management of patients with VAP.

Impact of the implementation of a therapeutic guideline on the treatment of nosocomial pneumonia acquired in the intensive care unit of a university hospital

OBJECTIVE

To evaluate the impact that the implementation of therapeutic guidelines has on the empirical treatment of nosocomial pneumonia.

METHODS

A clinical trial, using historical controls and involving current ICU patients who had acquired nosocomial pneumonia, was carried out from June of 2002 to June of 2003. All were treated according to therapeutic guidelines developed by the Commission for Nosocomial Infection Control of the institution (group with intervention). As controls, the medical charts of the patients who acquired nosocomial pneumonia between June of 2000 and June of 2001 (group without intervention) were analyzed. Mortality and mean treatment period, as well as the length of hospital and ICU stays, were determined for the patients who acquired nosocomial pneumonia.

RESULTS

Mortality associated with pneumonia was lower in the group treated according to the therapeutic guidelines (26 vs. 53.6%; p = 0.00). As for overall mortality, there was no statistically significant difference between the two periods (51 vs. 57.9%; p = 0.37). There was also no difference in the type of microorganisms isolated, treatment period, length of hospital stay or length of ICU stay.

CONCLUSION

The implementation of therapeutic guidelines for the treatment of nosocomial pneumonia acquired in the ICU can be efficacious in decreasing mortality rates.

A randomized study of sequential intravenous/oral moxifloxacin in comparison to sequential intravenous ceftriaxone/oral cefuroxime axetil in patients with hospital-acquired pneumonia

BACKGROUND

Empiric treatment of hospital-acquired pneumonia (HAP) should be focused on the suspected pathogens. We evaluated the efficacy and safety of moxifloxacin vs ceftriaxone in patients with HAP without risk of infections with Pseudomonas aeruginosa and other non-fermentative Gram-negative bacteria.

PATIENTS AND METHODS

We performed a prospective, randomized, non-blind, multicentric and multinational study to compare the efficacy and safety of moxifloxacin 400 mg IV once daily followed by oral moxifloxacin 400 mg once daily to ceftriaxone 2 g IV once daily followed by oral cefuroxime axetil 500 mg twice daily to treat mild-to-moderate HAP in adult patients requiring initial parenteral therapy. The primary efficacy variable was clinical response 7-10 days after the end of a 7-14-day treatment period, secondary endpoints included clinical and bacteriologic response at different intervals for up to 31 days after treatment. The trial was terminated prematurely due to slow patient recruitment.

RESULTS

A total of 161 subjects (87 men, 74 women) between 18 and 95 years of age were enrolled, 120 of whom were eligible for per protocol efficacy analyses (60 each in the moxifloxacin and the comparator groups). Clinical success rates were 87% for moxifloxacin and 83% for the comparator [95% CI (-9.77 to 15.96%)]. The results for secondary endpoints were comparable between groups. Both treatments were safe and well tolerated.

CONCLUSION

Moxifloxacin IV/oral can be considered as a possible alternative for the antibiotic treatment of patients with mild-to-moderate nosocomial pneumonia without risk factors for highly resistant microorganisms.

Principles of antimicrobial therapy: what should we be using?

Although the use of antimicrobials has had an insurmountable impact on preventing patient morbidity and mortality, problems with antimicrobial resistance and antimicrobial-induced diarrhea are becoming more apparent in human and veterinary medicine. The mortality associated with nosocomial infection with antimicrobial-resistant bacteria in human patients is alarming. Similarly, in veterinary medicine, the morbidity and high cost of treatment of patients with postoperative infection, for example, are concerns. Specifically in equine medicine, the high morbidity and mortality associated with antimicrobial-induced diarrhea have been devastating in many equine practices. Misuse of antimicrobials is extremely common in human and veterinary medicine. All clinicians have the responsibility to consider the appropriateness of their antimicrobial use carefully and, whenever possible, to minimize antimicrobial administration to patients.

Adverse Hospital Outcomes Associated With the Choice of Empiric Antibiotics in Klebsiella pneumoniae Pneumonia: A Retrospective Observational Study

Introduction: In Malaysia, Klebsiella pneumoniae ranks high as a cause of adult pneumonia requiring hospitalisation. Patients and Methods: With concern over its rising microbial resistance, we explored the association of empiric antibiotics choices with the hospital outcomes of patients treated for microbial proven K. pneumoniae pneumonia in an urban-based teaching hospital. Results: In 313 eligible cases reviewed retrospectively, hospital mortality and requirement for ventilation were 14.3% and 10.8% respectively. Empiric regimes that had in vitro resistance to at least one empiric antibiotic (n = 90) were associated with higher hospital mortality (23.3% vs. 10.8%, P = 0.004) with risk increased by about two-fold [Odds ratio (OR), 2.5; 95% confidence interval (CI), 1.3 to 4.8]. Regimes (n = 84) other than the commonly recommended “standard” regimes (a β-lactam stable antibiotic with or without a macrolide) were associated with higher ventilation rates (16.7% vs. 8.8%, P = 0.047) with similar increased risk [OR, 2.0; 95% CI, 1.0 to 4.3]. Conclusions: Our findings reiterate the clinical relevance of in vitro microbial resistance in adult K. pneumoniae pneumonia and support empiric regimes that contain β-lactam stable antibiotics. Key words: In vitro resistance, Malaysia

Relationship between immunosuppression and intensive care unit-acquired multidrug-resistant bacteria: a case-control study

OBJECTIVE

To determine the relationship between immunosuppression and intensive care unit (ICU)-acquired multidrug-resistant (MDR) bacteria.

DESIGN

Retrospective case-control study based on prospectively collected data.

SETTING

A 30-bed medical and surgical ICU.

PATIENTS

All patients hospitalized >48 hrs in the ICU were eligible during a 2-yr period.

INTERVENTIONS

Immunosuppression was defined as active solid or hematologic malignancy, leucopenia, or chronic immunosuppressive treatment. MDR bacteria were defined as methicillin-resistant Staphylococcus aureus, ceftazidime- or imipenem-resistant Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia, and extending spectrum beta-lactamase producing Gram-negative bacilli. MDR bacteria screening (nasal, anal, and axilla swabs and tracheal aspirate in intubated patients) was performed at ICU admission and weekly. Only MDR bacteria isolated >48 hrs after ICU admission were taken into account; duplicates were excluded. Isolation measures were applied in all patients at ICU admission, in patients with MDR bacteria, and in patients with immunosuppression. Immunosuppressed patients (cases) were matched (1:1) with immunocompetent patients (controls) according to all the following criteria: age +/-5 yrs, Simplified Acute Physiology Score II +/-5, duration of ICU stay +/-3 days, and category of admission (medical/surgical). Risk factors for ICU-acquired MDR bacteria were determined using univariate and multivariate analyses.

MEASUREMENTS AND MAIN RESULTS

Of 1,065 eligible patients, nine patients were excluded for absence of MDR bacteria screening at ICU admission. One hundred thirty-three (12%) patients were immunosuppressed, and 128 (96%) of them were successfully matched. Mean time between ICU admission and first ICU-acquired MDR bacteria was 12 +/- 9 days. Incidence of MDR bacteria was significantly higher in cases than in controls (22 vs. 12 MDR bacteria/1000 ICU days, p = .004). However, immunosuppression was not independently associated with ICU-acquired MDR bacteria.Multivariate analysis identified prior antibiotic treatment and antibiotic treatment in the ICU as risk factors for ICU-acquired MDR bacteria (odds ratio [95% confidence interval] = 1.9 [1-3.6], p = .003; 11 [1.4-83], p = .02; respectively).

CONCLUSIONS

Immunosuppression is not independently associated with ICU-acquired MDR bacteria. However, infection control measures used in our ICU may have influenced this result.

Article Commentary: Strategies in the Prevention and Management of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is a leading cause of morbidity and mortality in the intensive care unit. Prevention of VAP is possible through the use of several evidence-based strategies intended to minimize intubation, the duration of mechanical ventilation, and the risk of aspiration of oropharyngeal pathogens. Current data favor the quantitative analysis of lower respiratory tract cultures for the diagnosis of VAP, accompanied by the initiation of broad-spectrum empiric antimicrobial therapy based on patient risk factors for infection with multi-drug-resistant pathogens and data from unit-specific antibiograms. Eventual choice of antibiotic and duration of therapy are selected based on culture results and patient stability, with an emphasis on minimization of unnecessary antibiotic use.

Inadequate treatment of ventilator-associated pneumonia: risk factors and impact on outcomes

Initial antibiotic therapy is an important determinant of clinical outcomes in ventilator-associated pneumonia (VAP). Several studies have investigated this issue, with conflicting results. This study investigated risk factors of inadequate empirical antimicrobial therapy and its impact on outcomes for patients with a clinical diagnosis of VAP. The primary outcome was adequacy of antimicrobial therapy. Secondary outcomes were duration of mechanical ventilation, hospital and intensive care unit (ICU) lengths of stay, and mortality due to VAP. Mean age was 62.9+/-15.2 years, mean APACHE (Acute Physiological Assessment and Chronic Health Evaluation) II score was 20.1+/-8.1 and mean MODS (Multiple Organ Dysfunction Score) was 3.7+/-2.5. Sixty-nine (45.7%) of 151 patients with a clinical diagnosis of VAP received inadequate antimicrobial treatment for VAP initially. There were 100 (66.2%) episodes of VAP caused by multidrug-resistant pathogens, of which 56% were inadequately treated, whereas the rate of inadequate antimicrobial therapy for VAP caused by susceptible-drug pathogens was 25.5% (P<0.001). Multiple logistic regression analysis revealed that the risk of inadequate antimicrobial treatment was more than twice as great for patients with late-onset VAP [odds ratio (OR), 2.93; 95% confidence interval (CI), 1.30-6.64; P=0.01], and more than three times for patients with VAP caused by multidrug-resistant pathogens (OR, 3.07; 95% CI, 1.29-7.30; P=0.01) or with polymicrobial VAP (OR, 3.67; 95% CI, 1.21-11.12; P=0.02). Inadequate antimicrobial treatment was associated with higher mortality for patients with VAP. Two of three independent risk factors for treatment inadequacy were associated with the isolation and identification of micro-organisms.

Prospective assessment of fluoroquinolone use in a teaching hospital

The aim of this study was to review the use of fluoroquinolone (FQ) drugs in a teaching hospital and to bring to light the factors associated with FQ misuse. A prospective observational study of FQ prescriptions was conducted in a 2,200-bed teaching hospital. Every hospitalized patient receiving a FQ drug during the 3-week survey period was included. A questionnaire was filled out using medical records and face-to-face interviews with FQ prescribers. An infectious diseases specialist reviewed the questionnaires and analyzed FQ therapy according to local guidelines for FQ prescription. Among the group of 174 patients included, FQ therapy was inappropriate in 88 cases (50.6%; 95% CI 43-58) for the following reasons: inappropriate clinical setting, 43; non-first-line recommendation, 24; inappropriate choice of FQ agent, 9; and inappropriate combination of FQs, 12. FQ prescriptions did not comply with prescription rules in 45 cases (25.9%; 95% CI 20-33). Appropriateness and compliance overlapped for 17 of these 45 patients who received an inappropriate FQ course that did not comply with prescription rules. Finally, FQ therapy was misused for 116 of the 174 patients (66.6%; 95% CI 59-74). Characteristics linked with FQ misuse were hospitalization in surgical wards (p = 0.03), intravenous therapy (p < 0.01), and presumptive therapy (p = 0.05). The FQ misuse rate progressively decreased during the survey period (p = 0.04). FQ misuse was a common phenomenon in the teaching hospital studied. The significant improvement in FQ prescribing practices observed during the study period demonstrates that frequent review of antibiotic use with prescribers is warranted.

Ventilator-associated pneumonia: what is new?

BACKGROUND

Ventilator-associated pneumonia (VAP) is the most frequent intensive care unit (ICU)-acquired infection among patients receiving mechanical ventilation. Failure to initiate appropriate and adequate therapy (i.e., the etiologic organism is sensitive to the therapeutic agent, the dose is optimal, and the route of administration is correct) promptly in patients with VAP has been associated consistently with higher mortality rates. However, effective antimicrobial therapy for patients with true VAP can be achieved while avoiding excessive antibiotic use and the emergence of multidrug-resistant strains in the ICU.

METHOD

Review of the pertinent English-language literature.

RESULTS

Antimicrobial therapy for patients with VAP should follow a two-stage process. The first stage is identifying true pneumonia rapidly and starting therapy with an empirical regimen that is likely to be appropriate. In general, this requires using broad-spectrum antibiotics in all patients in whom there is a possibility that the etiologic pathogen could be difficult to treat (e.g., multi-drug-resistant pathogen). The second stage focuses on trying to achieve this objective without overusing and abusing antibiotics and combines a number of steps, such as stopping therapy in patients with a low probability of the disease, streamlining treatment once the etiologic agent is known, switching to monotherapy after three to five days, and shortening the duration of therapy to seven or eight days, as dictated by the patient's clinical response to therapy and information about the bacteriology of the infection.

CONCLUSION

Although such a strategy seems a logical way to manage patients with VAP, data are still needed to determine how best to achieve this process.

Using local microbiologic data to develop institution-specific guidelines for the treatment of hospital-acquired pneumonia

BACKGROUND

While current guidelines recommend consideration of local microbiologic data when selecting empiric treatment for hospital-acquired pneumonia (HAP), few specifics of how to do this have been offered.

METHODS

We conducted a retrospective analysis of HAP pathogens in 111 consecutive patients who acquired HAP during July to December 2004 and had a corresponding positive culture finding for a bacterial pathogen. These data were used to develop institution-specific guidelines.

RESULTS

The most common bacteria identified were Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa, which were associated with 38%, 25%, and 19% of pneumonias, respectively. Susceptibility of Gram-negative bacteria to piperacillin-tazobactam and cefepime was 80% and 81%, respectively. The isolation of organisms resistant to piperacillin-tazobactam or cefepime was significantly more frequent in patients who had been hospitalized > or = 10 days. Of Gram-negative isolates resistant to piperacillin-tazobactam or cefepime, ciprofloxacin was active against < 10%, while amikacin was active against > 80%. New treatment guidelines were developed that divided the American Thoracic Society/Infectious Diseases Society of America "late onset/risk of multidrug-resistant pathogens" group of patients into two subcategories: "early-late" pneumonias (< 10 days of hospitalization) and "late-late" pneumonias (> or = 10 days of hospitalization). Guideline-directed treatment regimens would be predicted to provide adequate initial therapy for > 90% of late-onset pneumonias at our institution.

CONCLUSIONS

Current guidelines suggest adding either an aminoglycoside or a fluoroquinolone to beta-lactam therapy for empiric Gram-negative coverage. However, in our institution, adding ciprofloxacin would not appreciably enhance the likelihood of providing initial appropriate antibiotic coverage. This underscores the importance of employing a systematic analysis of local data when developing treatment guidelines.

Use of quantitative cultures and reduced duration of antibiotic regimens for patients with ventilator-associated pneumonia to decrease resistance in the intensive care unit

Ventilator-associated pneumonia is responsible for approximately half of the infections acquired in the intensive care unit and represents one of the principal reasons for the prescription of antibiotics in this setting. Invasive diagnostic methods, including bronchoalveolar lavage and/or protected specimen bronchial brushing, could improve the identification of patients with true bacterial pneumonia and facilitate decisions of whether to treat. These techniques also permit rapid optimization of the choice of antibiotics in patients with proven bacterial infection, once the results of respiratory tract cultures become available, based on the identity of the specific pathogens and their susceptibility to specific antibiotics, to avoid prolonged use of a broader spectrum of antibiotic therapy than is justified by the available information. Because unnecessary prolongation of antibiotic therapy for patients with true bacterial infection may lead to the selection of multidrug-resistant microorganisms without improving clinical outcome, efforts to reduce the duration of therapy for nosocomial infections are also warranted. An 8-day regimen can probably be standard for patients with ventilator-associated pneumonia. Possible exceptions to this recommendation include immunosuppressed patients, patients who are bacteremic or whose initial antibiotic therapy was not appropriate for the causative microorganism(s), and patients whose infection is with very difficult-to-treat microorganisms and show no improvement in clinical signs of infection.

Antibiotic use in two cohorts of German intensive care units

Antibiotic use was evaluated in two cohorts of intensive care units (ICUs) in Germany. One cohort included ICUs participating in a surveillance programme (N=34) collecting antibiotic use and bacterial resistance data, with quarterly feedback. The second ICU cohort was from a cross-sectional study and represented a sample from hospitals in South-west Germany (N=58). Two dose definitions were used. These were the World Health Organization/Anatomical Therapeutic Chemical Classification (ATC) 2001 definition of defined daily dose (DDD), and a definition of recommended daily dose (RDD) that better reflected the currently prescribed dosages of parenteral drugs for hospitalized patients. Data were expressed as DDD or RDD per 100 patient-days. It was determined whether hospital size and affiliation, year of study and ICU type had an influence on overall use of antibiotics. Overall use differed between the two ICU cohorts irrespective of the dose definitions used. High use of antibiotics was primarily associated with hospital affiliation (university vs non-university) and hospital size. Mean overall use of antibiotics in non-university hospital ICUs ranged between 106 and 111 DDD/100 (59 and 67 RDD/100) for different hospital size categories, compared with 140 DDD/100 (87 RDD/100) in university hospital ICUs. In conclusion, in order to compare the use of antibiotics between ICU cohorts and to assess trends over time, data adjustment is required for hospital affiliation and size.

Activity of meropenem and comparators against Pseudomonas aeruginosa and Acinetobacter spp. isolated in the MYSTIC Program, 2002-2004

This study examines the susceptibilities of meropenem and other broad-spectrum antimicrobials tested against bacterial isolates collected from hospitalized patients during 2002-2004 from worldwide medical centers participating in the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program. The in vitro activity of meropenem and 5 comparator antimicrobial agents was assessed against Pseudomonas aeruginosa and Acinetobacter spp. Generally, the susceptibility of Australasian and North American isolates was higher than that of the European and South American isolates. The rank order of activity of the antimicrobial agents tested against a worldwide collection of P. aeruginosa was piperacillin/tazobactam (77.7% susceptible) > meropenem (75.4%) > ceftazidime (70.0%) > imipenem (69.7%) > gentamicin (66.1%) > ciprofloxacin (62.0%). Against a worldwide collection of Acinetobacter spp. meropenem (76.1% susceptible) was the most active compound followed by imipenem (74.7%) > gentamicin (51.9%) > ciprofloxacin (40.5%) > piperacillin/tazobactam (39.8%) > ceftazidime (38.1%). The carbapenems appear to be a valuable option for the treatment of serious nosocomial infections caused by P. aeruginosa or Acinetobacter spp. over a broad geographical region.

Comparison of antimicrobial cycling and mixing strategies in two medical intensive care units*

OBJECTIVE

To compare a mixing vs. a cycling strategy of use of anti-Pseudomonas antibiotics on the acquisition of resistant Gram-negative bacilli in the critical care setting.

DESIGN

Prospective, open, comparative study of two strategies of antibiotic use.

SETTING

Two medical intensive care units of a university hospital.

PATIENTS

A total of 346 patients admitted for >or=48 hrs to two separate medical intensive care units during an 8-month period.

INTERVENTIONS

Patients, who according to the attending physician's judgment required an anti-Pseudomonas regimen, were assigned to receive cefepime/ceftazidime, ciprofloxacin, a carbapemen, or piperacillin-tazobactam in this order. "Cycling" was accomplished by prescribing one of these antibiotics during 1 month each. "Mixing" was accomplished by using the same order of antibiotic administration on consecutive patients. Interventions were carried out during two successive 4-month periods, starting with mixing in one unit and cycling in the other.

MEASUREMENTS AND MAIN RESULTS

Swabbing of nares, pharynx, and rectum and culture of respiratory secretions were obtained thrice weekly. The main outcome variable was the proportion of patients acquiring enteric or nonfermentative Gram-negative bacilli resistant to the antibiotics under intervention. The scheduled cycling of antibiotics was only partially successful. Although the expected antibiotic was the most prevalent anti-Pseudomonas agent used within the corresponding period, it never accounted for >45% of all anti-Pseudomonas antimicrobials administered. During mixing, a significantly higher proportion of patients acquired a strain of Pseudomonas aeruginosa resistant to cefepime (9% vs. 3%, p = .01), and there was a trend toward a more frequent acquisition of resistance to ceftazidime (p = .06), imipenem (p = .06), and meropenem (p = .07). No differences in the rate of acquisition of potentially resistant Gram-negative bacilli or incidence of intensive care unit-acquired infections and infections due to particular organisms were observed.

CONCLUSIONS

In critically ill medical patients, a strategy of monthly rotation of anti-Pseudomonas beta-lactams and ciprofloxacin may perform better than a strategy of mixing in the acquisition of P. aeruginosa resistant to selected beta-lactams.

Use of Broad-Spectrum Antimicrobials for the Treatment of Pneumonia in Seriously Ill Patients: Maximizing Clinical Outcomes and Minimizing Selection of Resistant Organisms

Among various risk factors for death among critically ill patients with serious infection, inappropriate antimicrobial therapy is an important factor that clinicians can modify directly. The presence of multidrug-resistant bacteria is the primary reason that patients with ventilator-associated pneumonia receive inappropriate antimicrobial therapy. Empirical antimicrobial therapy for ventilator-associated pneumonia should be initiated promptly and should have a broad spectrum that covers all potential antimicrobial-resistant pathogens. Delaying the start of therapy or modifying an inappropriate antimicrobial regimen does not improve outcome, probably because the change comes too late to redirect the course of illness. Timely empirical therapy with highly effective agents that are rapidly bactericidal could minimize the emergence of resistance. Broad-spectrum therapy should be streamlined (i.e., de-escalated), as appropriate, on the basis of microbiological data and clinical response. Switching to narrower-spectrum therapy that is directed by culture results may minimize the emergence of resistance. For some patients, clinical response will allow a shortening of the duration of antimicrobial therapy.

Antimicrobial therapy in critically ill patients: a review of pathophysiological conditions responsible for altered disposition and pharmacokinetic variability

Antimicrobials are among the most important and commonly prescribed drugs in the management of critically ill patients. Selecting the appropriate antimicrobial at the commencement of therapy, both in terms of spectrum of activity and dose and frequency of administration according to concentration or time dependency, is mandatory in this setting. Despite appropriate standard dosage regimens, failure of the antimicrobial treatment may occur because of the inability of the antimicrobial to achieve adequate concentrations at the infection site through alterations in its pharmacokinetics due to underlying pathophysiological conditions. According to the intrinsic chemicophysical properties of antimicrobials, hydrophilic antimicrobials (beta-lactams, aminoglycosides, glycopeptides) have to be considered at much higher risk of inter- and intraindividual pharmacokinetic variations than lipophilic antimicrobials (macrolides, fluoroquinolones, tetracyclines, chloramphenicol, rifampicin [rifampin]) in critically ill patients, with significant frequent fluctuations of plasma concentrations that may require significant dosage adjustments. For example, underexposure may occur because of increased volume of distribution (as a result of oedema in sepsis and trauma, pleural effusion, ascites, mediastinitis, fluid therapy or indwelling post-surgical drainage) and/or enhanced renal clearance (as a result of burns, drug abuse, hyperdynamic conditions during sepsis, acute leukaemia or use of haemodynamically active drugs). On the other hand, overexposure may occur because of a drop in renal clearance caused by renal impairment. Care with all these factors whenever choosing an antimicrobial may substantially improve the outcome of antimicrobial therapy in critically ill patients. However, since these situations may often coexist in the same patient and pharmacokinetic variability may be unpredictable, the antimicrobial policy may further benefit from real-time application of therapeutic drug monitoring, since this practice, by tailoring exposure to the individual patient, may consequently be helpful both in improving the outcome of antimicrobial therapy and in containing the spread of resistance in the hospital setting.

A review of guidelines for antibacterial use in acute exacerbations of chronic bronchitis

Acute exacerbations of chronic bronchitis (AECB) affect a significant proportion of the adult population worldwide and are associated with a substantial socioeconomic burden. The majority of episodes of AECB are bacterial in aetiology and patients are generally treated empirically with orally administered antibacterial agents. Guidelines for the management of AECB have been developed by a number of national health authorities and international organisations, with the aim of promoting rational selection of antibacterial therapy to minimise the risk of treatment failure and subsequent hospitalisation while containing the development and spread of antibacterial resistance. This paper reviews a number of recently published or updated AECB treatment guidelines, focusing on patient stratification strategies, antibacterial treatment recommendations, and newer antibacterial treatment options, including respiratory fluoroquinolones and the ketolide telithromycin, which have recently been added to a number of national treatment guidelines.

Nature of gram-negative rod antibiotic resistance during antibiotic rotation

PURPOSE

The aim of this study was to characterize the evolution of gram-negative antibiotic resistance during a study of empiric antibiotic rotation.

METHODS

We showed previously that quarterly rotation of a single antibiotic class is inferior to cycling two antibiotics per quarter for empiric treatment of gram-negative rod (GNR) infections, as evidenced by increased incidence of antibiotic-resistant GNR (rGNR) infections. Resistance patterns were examined by quantifying GNRs resistant to one or more of the following drug classes: Aminoglycosides, cephalosporins, carbapenems, fluoroquinolones, or piperacillin-tazobactam. For all rGNR isolates, the mean number of antibiotic classes to which an organism was resistant was calculated per quarter, as was the number of rGNR species.

RESULTS

Single-antibiotic rotation (SAR) was associated with significant increases in the incidence of piperacillin-tazobactam (p < 0.0005) and cephalosporin (p = 0.003) resistance, reaching nearly 25% and 30% of rGNR isolates respectively, most notably during the quarter of designated cephalosporin use (VI). Multi-drug resistance emerged over time; resistant classes/resistant GNR isolates ranged from 1.2 in the dual-antibiotic rotation (DAR) to 1.9 in the SAR period (p = 0.02). Resistance was evident in an increasing number of unique GNR species. On average, 1.3 species were isolated per month in the DAR period and 3.0/month in the SAR period (p = 0.004), but proportionally, no single GNR species became significantly more resistant across time. Compared to only 5.8% in the DAR period, 29% noncompliance was observed in the SAR, with a six-fold increase in the use of nonscheduled empiric antibiotics due to the presence of an organism resistant to the scheduled rotation drug.

CONCLUSIONS

A single-antibiotic rotation is associated with increased incidence and heterogeneity of resistant GNR isolates, as well as increased multiple-drug-class resistance. The attenuation of resistance observed in the single-antibiotic rotation may reflect the effect of unintended antibiotic heterogeneity driven by increasing resistance to the antibiotic class recommended for use each quarter. This suggests that reliance on a single antibiotic class for empiric treatment of GNR infection exerts sufficient pressure within the environment to encourage the development of diversified resistance, as well as cross-resistance over antibiotic classes, thus narrowing the availability of effective antibiotic treatment.