Bloodstream infections: epidemiology and resistance

Bloodstream infections in the neonatal intensive care unit (NICU) are associated with many adverse outcomes in infants, including increased length of stay and cost, poor neurodevelopmental outcomes, and death. Attention to the insertion and maintenance of central lines, along with careful review of when the catheters can be safely discontinued, can minimize central-line-associated bloodstream infections rates. Good antibiotic stewardship can further decrease the incidence of bloodstream infections, minimize the emergence of drug-resistant organisms or Candida as pathogens in the NICU, and safeguard the use of currently available antibiotics for future infants.

Prophylactic antibiotics for children with recurrent urinary tract infections

Prophylactic antibiotics for urinary tract infections are no longer routinely recommended. A large number of children must be given prophylaxis to prevent one infection and antibiotic resistance is a major concern when treating community-acquired urinary tract infections. The results of three recent significant studies are examined, with focus on the efficacy of prophylaxis, and recommendations are made.

Antibiotic stewardship programmes and the surgeon's role

Inappropriate antibiotic use is a frequent occurrence, especially in surgical units. Among the unnecessary costs of such usage are unfavourable outcomes for patients and the emergence and spread of resistant bacteria. Antibiotic stewardship programmes aim to limit the spread of antibiotic resistance by promoting thoughtful prescribing of antibiotics. Such programmes usually try to control inappropriate use of antibiotics; to optimize the choice of drug, dosing, route, and duration of therapy; to maximize clinical cure or prevention of infection; and to limit unwanted effects and excess cost. In this paper, I discuss the impact of improper use of antibiotics and outline why I believe that antibiotic stewardship is likely to be the best way of dealing with it. Engagement of surgeons in antibiotic stewardship programmes is crucial to their success.

Antimicrobial use metrics and benchmarking to improve stewardship outcomes: methodology, opportunities, and challenges

Measurement of antimicrobial use before and after an intervention and the associated outcomes are key activities of antimicrobial stewardship programs. In the United States, the recommended metric for aggregate antibiotic use is days of therapy/1000 patient-days. Clinical outcomes, including response to therapy and bacterial resistance, are critical measures but are more difficult to document than economic outcomes. Interhospital benchmarking of risk adjusted antimicrobial use is possible, although several obstacles remain before it can have an impact on patient care. Many challenges for stewardship programs remain, but the methods and science to support their efforts are rapidly evolving.

Procalcitonin: potential role in diagnosis and management of sepsis

Sepsis is an important cause of worldwide morbidity and mortality. Early recognition and diagnosis are keys to achieving improved outcomes. Procalcitonin has been widely investigated as a potential biomarker for sepsis. Furthermore, management of sepsis and other infectious disease is becoming increasingly complicated by the emergence of antibiotic resistant strains of pathogens. Good antibiotic governance is important in reducing the risk of the development of further antibiotic resistance. We reviewed the current literature on the use of procalcitonin in sepsis to determine whether it should be recommended for use in either of these roles. Procalcitonin should not be used as a stand-alone diagnostic test to rule-in or rule-out sepsis or bacterial infection, or for prognostication, in the absence of clinical judgment. Used as part of a clinical algorithm, however, it has been shown to reduce antibiotic prescribing in critical care environments and for respiratory tract infections.

Practice of switch from intravenous to oral antibiotics

Hospitalized patients initially on intravenous antibiotics can be safely switched to an oral equivalent within the third day of admission once clinical stability is established. This conversion has many advantages as fewer complications, less healthcare costs and earlier hospital discharge. The three types of intravenous to oral conversion include sequential, switch, and step-down therapy. The aim of the study was to evaluate the practice of switching from intravenous to oral antibiotics, its types and its impact on the clinical outcomes. This was a retrospective observational study conducted in three Lebanese hospitals over a period of six months. Adult inpatients on intravenous antibiotics for 2 days and more were eligible for study enrollment. Excluded were patients admitted to care or surgery units, or those with gastrointestinal diseases, infections that require prolonged course of parenteral therapy, or malignancies.

The study showed that among 452 intravenous antibiotic courses from 356 patients who were eligible for conversion, only one third were switched and the others continued on intravenous antibiotics beyond day 3 (P <0.0001). The mean duration of intravenous therapy of converted patients was markedly shorter than the non-converted (P <0.0001) with no significant change in the mean length of stay. Fluoroquinolones and macrolides were the most commonly converted antibiotics. However, the sequential therapy was the major type of conversion practiced in this study. Based on the study findings, a significant proportion of patients can be considered for switch. This emphasizes an important gap in the field of conversion from intravenous to oral antibiotic therapy and the need for integration and reinforcement of the appropriate Antibiotic Stewardship Programs in hospitals.

European survey on principles of prudent antibiotic prescribing teaching in undergraduate students

We surveyed European medical schools regarding teaching of prudent antibiotic prescribing in the undergraduate curriculum. We performed a cross-sectional survey in 13 European countries (Belgium, Croatia, Denmark, France, Germany, Italy, Netherlands, Norway, Serbia, Slovenia, Spain, Switzerland, United Kingdom) in 2013. Proportional sampling was used, resulting in the selection of two to four medical schools per country. A standardized questionnaire based on literature review and validated by a panel of experts was sent to lecturers in infectious diseases, medical microbiology and clinical pharmacology. In-depth interviews were conducted with four lecturers. Thirty-five of 37 medical schools were included in the study. Prudent antibiotic use principles were taught in all but one medical school, but only four of 13 countries had a national programme. Interactive teaching formats were used less frequently than passive formats. The teaching was mandatory for 53% of the courses and started before clinical training in 71%. We observed wide variations in exposure of students to important principles of prudent antibiotic use among countries and within the same country. Some major principles were poorly covered (e.g. reassessment and duration of antibiotic therapy, communication skills). Whereas 77% of the respondents fully agreed that the teaching of these principles should be prioritized, lack of time, mainly due to rigid curriculum policies, was the main reported barrier to implementation. Given the study design, these are probably optimistic results. Teaching of prudent antibiotic prescribing principles should be improved. National and European programmes for development of specific learning outcomes or competencies are urgently needed.

Restrictive reporting of selected antimicrobial susceptibilities influences clinical prescribing

BACKGROUND

Cascade and restrictive reporting are useful strategies to enhance antibiotic stewardship programs.

METHODS

We combined both strategies to improve the prescribing of antibiotics aimed at Gram-negative infections.

RESULTS

For Enterobacter aerogenes, the susceptibility rates to amikacin increased from 10% to 100%; for third generation cephalosporins, these rates increased from 55% to 89%. The susceptibility rates of E. aerogenes to cefepime and piperacillin-tazobactam changed little, and the ampicillin susceptibility decreased from 30% in 2009 to 11% in 2010. For Proteus mirabilis, the susceptibility rates increased for third-generation cephalosporins (48% vs. 92%) and piperacillin-tazobactam (10% vs. 98%), with minimal changes for cefepime (96% vs. 93%), ampicillin (69% vs. 73%) and amikacin (96% vs. 84%). For Pseudomonas aeruginosa, the susceptibility rates improved slightly for third-generation cephalosporins (81% vs. 91%) but reduced for piperacillin-tazobactam (99% vs. 59%). Hospital-acquired Clostridium difficile infections decreased from 0.11 to 0.07 per 1000 patient days.

CONCLUSIONS

Selective reporting helps physicians choose the most appropriate antibiotics for their patients within a stewardship program, with reduced C. difficile infection.

Ethical dilemmas in antibiotic treatment: focus on the elderly

Maximal antibiotic treatment for all patients suspected of harbouring a bacterial infection is non-viable, because it will rapidly induce resistance and exhaust this finite resource. This raises two ethical dilemmas: the question of whether we are justified in increasing the danger to a present, named, patient so as to benefit future, unknown, patients; and whether we are allowed to do so without asking the present patient for consent. Although the considerations for healthy elderly patients are similar to younger adults, the answers are complex when addressing patients with dementia, severely reduced quality of life and at end of life. We argue that a public debate on the balance between benefit to a present patient versus harm to future patients should be conducted. Such a debate should include examinations of scenarios in which antibiotic treatment does not gain any benefit in a patient with infection: at the end of life; in situations in which resistance is such that empirical antibiotic treatment seldom matches the susceptibilities of the pathogen; and in patients with no quality of life. An explicit cost-benefit model, incorporating quality of life and risk of resistance, in computerized decision support might obviate a clinician's need to deal with these difficult issues at bedside.

Special considerations of antibiotic prescription in the geriatric population

Infectious diseases pose a major challenge in the elderly for two reasons: on the one hand the susceptibility to infection increases with age and when infections occur they often present atypically-on the other hand diagnostic uncertainty is much more pronounced in the geriatric population. Reconciling the opposing aspects of optimizing patient outcomes while avoiding antibiotic overuse requires significant expertise that can be provided by an infectious diseases consultant. In addition, geriatric facilities are reservoirs for multidrug-resistant organisms and other nosocomial pathogens, and infectious diseases consultants also play a vital role in assuring appropriate infection control measures. In this review we outline the challenges of diagnosis and management of infectious diseases in the elderly, and discuss the importance of appropriate antibiotic use in the elderly in order to demonstrate the value of the infectious diseases consultant in this special setting.

Scientific evidence and research in antimicrobial stewardship

Evaluating the impact of antibiotic stewardship programs is challenging. There is evidence that they are effective in terms of reducing the consumption and cost of antibiotics, although establishing their impact on antimicrobial resistance (beyond restrictive policies in outbreaks caused by specific antimicrobial resistant organisms) and clinical outcomes is more difficult. Proper definitions of exposure and outcome variables, the use of advanced and appropriate statistical analyses and well-designed quasi-experimental studies would more accurately support the conclusions. Cluster randomized trials should be used whenever possible and appropriate, although the limitations of this approach should also be acknowledged. These issues are reviewed in this paper. We conclude that there are good research opportunities in the field of antibiotic stewardship.

Nasal screening is useful in excluding methicillin-resistant Staphylococcus aureus in ventilator-associated pneumonia

Methicillin-resistant Staphylococcus aureus screening performed for infection control purposes may be useful in guiding decisions regarding the use of broad-spectrum antibiotics in the intensive care unit. A cohort study of adults with ventilator-associated pneumonia (VAP) found that admission MRSA nasal swabs had a negative predictive value of 94% for later MRSA VAP.

Excluding infection through procalcitonin testing improves outcomes of congestive heart failure patients presenting with acute respiratory symptoms: results from the randomized ProHOSP trial

BACKGROUND/OBJECTIVES

We sought to determine whether exclusion of infection and antibiotic stewardship with the infection biomarker procalcitonin improves outcomes in congestive heart failure (CHF) patients presenting to emergency departments with respiratory symptoms and suspicion of respiratory infection.

METHODS

We performed a secondary analysis of patients with a past medical history of CHF formerly included in a Swiss multicenter randomized-controlled trial. The trial compared antibiotic stewardship according to a procalcitonin algorithm or state-of-the-art guidelines (controls). The primary endpoint was a 30-day adverse outcome (death, intensive care unit admission); the secondary endpoints included a 30-day antibiotic exposure.

RESULTS

In the 110/233 analyzed patients (47.2%) with low initial procalcitonin (<0.25 μg/L), suggesting the absence of systemic bacterial infection, those randomized to procalcitonin guidance (n=50) had a significantly lower adverse outcome rate compared to controls (n=60): 4% vs. 20% (absolute difference -16.0%, 95% confidence interval (CI) -28.4% to -3.6%, P=0.01), and significantly reduced antibiotic exposure [days] (mean 3.7 ± 4.0 vs. 6.5 ± 4.4, difference -2.8 [95% CI, -4.4 to -1.2], P<0.01). When initial procalcitonin was ≥0.25 μg/L, procalcitonin-guided patients had significantly reduced antibiotic exposure due to early stop of therapy without any difference in adverse outcomes (25.8% vs. 24.6%, difference [95% CI] 1.2% [-14.5% to 16.9%, P=0.88]).

CONCLUSIONS

CHF patients presenting to the emergency department with respiratory symptoms and suspicion for respiratory infection had decreased antibiotic exposure and improved outcomes when procalcitonin measurement was used to exclude bacterial infection and guide antibiotic treatment. These data provide further evidence for the potential harmful effects of antibiotic / fluid treatment when used instead of diuretics and heart failure medication in clinically symptomatic CHF patients without underlying infection.

The effect of pharmacy restriction of clindamycin on Clostridium difficile infection rates in an orthopedics ward

A high consumption of clindamycin was noted in an orthopedics ward with high rates of Clostridium difficile infection (CDI). We restricted clindamycin for the entire ward. A reduction of 88% in CDI (1.07 to 0.12 × 1,000 patients-days, P = .056) and 84% for all-cause diarrhea (2.40 to 0.38 × 1,000 patients-days, P = .021) was achieved. Clindamycin was reduced 92.61% without an increase in other antibiotics. We identified high consumption of clindamycin as a risk factor for CDI.

Increased moxifloxacin utilization associated with an unrestricted addition to a drug reimbursement formulary: A population-based analysis

OBJECTIVES

To determine whether utilization of moxifloxacin, a broad-spectrum fluoroquinolone antibiotic, has changed since its addition to the British Columbia provincial formulary in 2009 and to determine whether utilization was guideline concordant.

METHODS

BC PharmaNet prescriptions for moxifloxacin from 2001 to 2010 were anonymously linked to associated Medical Services Plan fee-for-service practitioner claims for indication-specific analysis. Prescribing trends for adults ≥18 years of age were described using defined daily dose (DDD) per 1000 person-years. Monthly utilization rates were fit to a linear regression model that controlled for seasonal variation to examine the effect of the formulary addition.

RESULTS

Utilization rose more than sevenfold throughout the study period, from 21.3 DDD per 1000 person-years in 2001 to 163.3 DDD per 1000 person-years in 2010. Although the formulary addition was not associated with an immediate increase in utilization (7.5% [95% CI -4.4% to 20.9%]; P=0.226), it was associated with an overall increase in utilization of 2.1% (95% CI 1.3% to 3.0%; P<0.001) for every month after 2009. Overall, only 29% of moxifloxacin prescriptions could be linked to a diagnostic code that was considered to be guideline concordant. In more than one-half of moxifloxacin prescriptions, the patient had not used another antibiotic in the previous 90 days. Among moxifloxacin prescriptions in which another antibiotic had been used in the previous 90 days, 41.5% were prescriptions for an alternative fluoroquinolone.

CONCLUSIONS

The formulary addition was associated with a sustained increase in moxifloxacin utilization over time. Moxifloxacin is often prescribed to patients for indications that are not guideline concordant or to patients who have not previously received first-line antibiotics.

Of stewardship, motherhood and apple pie

Antibiotic stewardship is universally agreed to be desirable, but optimal models for stewardship remain uncertain. UK stewardship targets the particular antibiotic families-cephalosporins and fluoroquinolones-blamed for the selection of Clostridium-difficile-associated disease. To balance this there have been dramatic increases in the use of penicillin-β-lactamase inhibitor combinations. By channelling selection pressure in this way, we hazard destroying the utility of these antibiotic classes in turn, as happened with gonorrhoea where penicillins, fluoroquinolones and cefixime were sequentially lost as therapies. Strikingly, in context, almost all carbapenemase-producers are highly resistant to penicillin-β-lactamase inhibitor combinations, which may select for them. There is an urgent need to explore an alternative stewardship model, seeking to limit total antibiotic use but to maintain heterogeneity in what is used, avoiding concentrated selection pressure. There is also a great need to improve and accelerate diagnostics for infection and resistance, reducing or removing the need for protracted empirical treatment with broad-spectrum agents.

Duration of antibiotic therapy for critically ill patients with bloodstream infections: A retrospective cohort study

BACKGROUND

The optimal duration of antibiotic treatment for bloodstream infections is unknown and understudied.

METHODS

A retrospective cohort study of critically ill patients with bloodstream infections diagnosed in a tertiary care hospital between March 1, 2010 and March 31, 2011 was undertaken. The impact of patient, pathogen and infectious syndrome characteristics on selection of shorter (≤10 days) or longer (>10 days) treatment duration, and on the number of antibiotic-free days, was examined. The time profile of clinical response was evaluated over the first 14 days of treatment. Relapse, secondary infection and mortality rates were compared between those receiving shorter or longer treatment.

RESULTS

Among 100 critically ill patients with bloodstream infection, the median duration of antibiotic treatment was 11 days, but was highly variable (interquartile range 4.5 to 17 days). Predictors of longer treatment (fewer antibiotic-free days) included foci with established requirements for prolonged treatment, underlying respiratory tract focus, and infection with Staphylococcus aureus or Pseudomonas species. Predictors of shorter treatment (more antibiotic-free days) included vascular catheter source and bacteremia with coagulase-negative staphylococci. Temperature improvements plateaued after the first week; white blood cell counts, multiple organ dysfunction scores and vasopressor dependence continued to decline into the second week. Among 72 patients who survived to 10 days, clinical outcomes were similar between those receiving shorter and longer treatment.

CONCLUSION

Antibiotic treatment durations for patients with bloodstream infection are highly variable and often prolonged. A randomized trial is needed to determine the duration of treatment that will maximize cure while minimizing adverse consequences of antibiotics.

Antimicrobial resistance: a global view from the 2013 World Healthcare-Associated Infections Forum

Antimicrobial resistance (AMR) is now a global threat. Its emergence rests on antimicrobial overuse in humans and food-producing animals; globalization and suboptimal infection control facilitate its spread. While aggressive measures in some countries have led to the containment of some resistant gram-positive organisms, extensively resistant gram-negative organisms such as carbapenem-resistant enterobacteriaceae and pan-resistant Acinetobacter spp. continue their rapid spread. Antimicrobial conservation/stewardship programs have seen some measure of success in reducing antimicrobial overuse in humans, but their reach is limited to acute-care settings in high-income countries. Outside the European Union, there is scant or no oversight of antimicrobial administration to food-producing animals, while evidence mounts that this administration leads directly to resistant human infections. Both horizontal and vertical infection control measures can interrupt transmission among humans, but many of these are costly and essentially limited to high-income countries as well. Novel antimicrobials are urgently needed; in recent decades pharmaceutical companies have largely abandoned antimicrobial discovery and development given their high costs and low yield. Against this backdrop, international and cross-disciplinary collaboration appears to be taking root in earnest, although specific strategies still need defining. Educational programs targeting both antimicrobial prescribers and consumers must be further developed and supported. The general public must continue to be made aware of the current scale of AMR's threat, and must perceive antimicrobials as they are: a non-renewable and endangered resource.

Knowledge, attitudes, and beliefs of French medical students about antibiotic prescribing and resistance

OBJECTIVES

We had for aim to learn about medical students' knowledge and perspectives on antibiotic prescribing and bacterial resistance.

METHODS

Penultimate and final year students at a French medical school were invited to participate in an anonymous online survey in summer 2012.

RESULTS

The response rate was 20% (60/297). Penultimate and final year students gave similar answers. Students felt more confident in diagnosing an infection, and less confident in choosing the correct dose and interval of antibiotic administration. Seventy-nine percent of students wanted more training on antibiotic treatments. Sixty-nine percent of students knew that antibiotic prescriptions were inappropriate or unnecessary in 21-60% of the cases, and 95% believed that these prescriptions were unethical. Only 27% knew that more than 80% of antibiotic prescriptions were made in community practice. Students believed that the most important causes of resistance were that too many prescriptions were made and broad-spectrum antibiotic use; 27% believed poor hand hygiene was "not at all important". Ninety-four percent believed resistance was a national problem, and 69% mentioned it as a problem in their hospital. Sixty-three percent thought that the antibiotics they would prescribe would contribute to resistance, and 96% thought resistance would be a greater problem in the future. Twenty-two percent knew MRSA bacteremia rates had decreased over the past decade in France.

CONCLUSIONS

Medical students are aware that antibiotic resistance is a current and growing problem. They would like more training on antibiotic selection.

Assessment of treatment patterns and patient outcomes before vs after implementation of a severity-based Clostridium difficile infection treatment policy. J Hosp Infect. 2013;85:28-32. [PMID: 23834988 DOI: 10.1016/j.jhin.2013.04.017]

BACKGROUND

National guidelines recommend oral vancomycin for severe Clostridium difficile infection (CDI) based on results from recent clinical trials demonstrating improved clinical outcomes. However, real-world data to support these clinical trials are scant.

AIM

To compare treatment patterns and patient outcomes of those treated for CDI before and after implementation of a severity-based CDI treatment policy at a tertiary teaching hospital.

METHODS

This study evaluated adult patients with a positive C. difficile toxin before and after implementation of a policy where patients with severe CDI given metronidazole were switched to oral vancomycin unless contra-indicated. Patients were stratified according to disease severity using a modified published severity score. Treatment patterns based on CDI severity and rates of refractory CDI were assessed.

FINDINGS

In total, 256 patients with CDI (mean age 66 years, standard deviation 17, 52% female) were evaluated (before implementation: N = 144; after implementation: N = 112). Use of oral vancomycin for severe CDI increased significantly from 14% (N = 8) to 91% (N = 48) following implementation of the policy (P < 0.0001). Refractory disease in patients with severe CDI decreased significantly from 37% to 15% following implementation of the policy (P = 0.035). No significant differences were noted among patients with mild to moderate CDI.

CONCLUSION

A severity-based CDI treatment policy at a tertiary teaching hospital increased the use of oral vancomycin and was associated with decreased rates of refractory CDI.

Revolutionising bacteriology to improve treatment outcomes and antibiotic stewardship

Laboratory investigation of bacterial infections generally takes two days: one to grow the bacteria and another to identify them and to test their susceptibility. Meanwhile the patient is treated empirically, based on likely pathogens and local resistance rates. Many patients are over-treated to prevent under-treatment of a few, compromising antibiotic stewardship. Molecular diagnostics have potential to improve this situation by accelerating precise diagnoses and the early refinement of antibiotic therapy. They include: (i) the use of 'biomarkers' to swiftly distinguish patients with bacterial infection, and (ii) molecular bacteriology to identify pathogens and their resistance genes in clinical specimens, without culture. Biomarker interest centres on procalcitonin, which has given good results particularly for pneumonias, though broader biomarker arrays may prove superior in the future. PCRs already are widely used to diagnose a few infections (e.g. tuberculosis) whilst multiplexes are becoming available for bacteraemia, pneumonia and gastrointestinal infection. These detect likely pathogens, but are not comprehensive, particularly for resistance genes; there is also the challenge of linking pathogens and resistance genes when multiple organisms are present in a sample. Next-generation sequencing offers more comprehensive profiling, but obstacles include sensitivity when the bacterial load is low, as in bacteraemia, and the imperfect correlation of genotype and phenotype. In short, rapid molecular bacteriology presents great potential to improve patient treatments and antibiotic stewardship but faces many technical challenges; moreover it runs counter to the current nostrum of defining resistance in pharmacodynamic terms, rather than by the presence of a mechanism, and the policy of centralising bacteriology services.