Appropriateness and delay to initiate therapy in ventilator-associated pneumonia

Experimental severe Pseudomonas aeruginosa pneumonia and antibiotic therapy in piglets receiving mechanical ventilation

BACKGROUND

Little is known about the general and local consequences of severe pneumonia under mechanical ventilation (SPMV) and how these are resolved with antibiotic therapy (ABT).

OBJECTIVES

To investigate the physiologic, biological, microbiological, and pathologic changes produced by experimental SPMV in a porcine model, and to evaluate the effect of ABT.

METHODS

Pseudomonas aeruginosa was inoculated in 12 large white-Landrace piglets receiving mechanical that were killed after 72 h if death did not occur before. Vital signs, serum and BAL cytokines, serum C-reactive protein (CRP), and graded postmortem lung pathology and cultures (blood and quantitative BAL and lung) were evaluated. Six piglets received inappropriate ABT (no ABT or ceftriaxone), and six piglets received appropriate ABT (ciprofloxacin).

MEASUREMENTS AND MAIN RESULTS

Pathologic and microbiological evidence of infection were present in all the animals in both groups. SPMV produced significant oxygenation and lung compliance worsening, increased serum CRP, and reduced BAL fluid tumor necrosis factor (TNF)-alpha. Arterial thrombosis in lung pathology was associated with higher temperature, hypoxemia and low lung compliance, higher initial serum CRP and TNF-alpha concentrations, and increased serum interleukin (IL)-6 and BAL IL-6 and TNF-alpha. Reduced ABT reduced body temperature and culture positivity.

CONCLUSIONS

This model resembles VAP and has been used for studying pulmonary infection and inflammation related to mechanical ventilation. ABT reduced fever and bacterial burden in SPMV but had no effect on cytokine or CRP concentrations, oxygenation, or lung mechanics. Pulmonary artery thrombosis was associated with worse response to infection.

Principles of Antimicrobial Use in Older Adults

The fundamental principles of treating infectious diseases apply to elderly patients, but certain aspects of therapy such as the selection of empiric regimens and risk stratification for severe or atypical disease are influenced by comorbidities, lifestyle, and immunosenescence. Knowledge of age-related changes in pharmacokinetic parameters and potential drug-drug interactions assists the clinician in determining appropriate dosing and monitoring parameters. Based on current evidence, the recommended approach includes careful selection and aggressive dosing of initial broad-spectrum antimicrobials followed by de-escalation to appropriate agents to maximize clinical outcomes and minimize toxicity and adverse effects. Greater enrollment of the elderly in therapeutic studies is needed to detect differences in the efficacy and safety of antimicrobials.

Adequacy of empirical antifungal therapy and effect on outcome among patients with invasive Candida species infections

OBJECTIVES

Although inadequate antimicrobial therapy has been demonstrated in multiple studies to increase the risk for death in bacterial infections, few data investigating the effect of antifungal therapy on outcome of serious fungal disease are available. We sought to assess the adequacy of empirical therapy and its effect on mortality in invasive Candida species infections.

METHODS

Population-based surveillance of all patients with Candida spp. cultured from blood and/or cerebrospinal fluid was conducted. Adequacy of empirical therapy was assessed according to published guidelines.

RESULTS

During a 5 year period, 207 patients had an invasive Candida spp. infection identified; in 199 cases (96%) adequate data were available for assessment of treatment and outcome at hospital discharge. One hundred and three (52%) cases were due to Candida albicans, 44 (22%) were due to Candida glabrata and the remainder were due to other species. Between the time of culture draw and reporting of a positive culture, only 64 (32%) patients were treated with empirical therapy; this was deemed adequate in 51 (26%). Patients who received adequate empirical therapy had a significant decrease in crude mortality [14/51 (27%) versus 68/148 (46%); risk ratio 0.60 (95% confidence interval 0.37-0.96); P = 0.02]. After adjusting for age and the need for intensive care unit admission in logistic regression analysis, the use of adequate empirical therapy was independently associated with a reduced risk for death [odds ratio 0.46 (95% confidence interval 0.22-1.00); P = 0.05].

CONCLUSIONS

Adequate empirical therapy is used in a minority of patients with invasive Candida spp. infections but is associated with improved survival.

Ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is a significant clinical infection affecting up to one-third of patients requiring mechanical ventilation, and is associated with significant attributable morbidity and mortality. Clinicians should have a heightened clinical suspicion for VAP with diagnostic goals focusing on accuracy; gathering of lower respiratory tract culture; and appropriate and timely initial antibiotic therapy. Early and adequate antibiotic therapy is important to optimize the management of patients with VAP. The incidence and etiologic patterns of the major pathogens causing VAP must be taken into account when making empiric antibiotic therapy choices. Subsequent de-escalation and prescription of an appropriate duration of therapy guided by clinical response and culture results may lead to decreased morbidity and future antibiotic resistance.

De-escalation therapy in ventilator-associated pneumonia

PURPOSE OF REVIEW

To describe the use of a 'de-escalation' strategy to deliver appropriate empiric therapy for ventilator-associated pneumonia, without the overuse of antibiotics.

RECENT FINDINGS

Initial empiric therapy can be appropriate in 80-90% of ventilator-associated pneumonia patients, if it is selected on the basis of local microbiologic data or individual patient surveillance cultures. Following initial empiric therapy, de-escalation means using microbiologic and clinical data to change from an initial broad-spectrum, multidrug empiric therapy regimen to a therapy with fewer antibiotics and agents of narrower spectrum. In spite of early success with this approach there is an opportunity to de-escalate more often, particularly in patients with negative pretherapy cultures, and in those whose cultures show multidrug-resistant organisms, including Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. In addition, it is possible to reduce the total duration of therapy, particularly when the initial therapy is accurate. When de-escalation has been employed, it has led to less antibiotic usage, shorter durations of therapy, fewer episodes of secondary pneumonia and reduced mortality, without increasing the frequency of antibiotic resistance.

SUMMARY

De-escalation is a promising strategy for optimizing the responsible use of antibiotics while allowing the delivery of prompt and appropriate empiric therapy of ventilator-associated pneumonia.

Hospital-acquired pneumonia in the 21st century: a review of existing treatment options and their impact on patient care

Hospital-acquired pneumonia is a common nosocomial infection, with significant morbidity and mortality, and represents a major therapeutic challenge to clinicians. The therapeutic approach must be patient-oriented and institution-specific. The specific risk factors of each patient, such as previous antibiotic exposure, underlying diseases, length of hospital stay and the local patterns of antimicrobial resistance, should guide physicians in their decision of the initial optimal empirical therapy. Delays in the initiation or inappropriate/inadequate initial therapy are related to increased mortality and worse outcomes. In responding patients, as soon as culture data are available, efforts should be made to change the initial broad spectrum antibiotic regimen to a more targeted one (de-escalation). The optimal duration of treatment is a matter of debate, but courses longer than 1 week are rarely justified.