Low Efficacy of Antibiotics Against Staphylococcus aureus Airway Colonization in Ventilated Patients.

Background: Airway-colonization by Staphylococcus aureus predisposes to the development of ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). Despite extensive antibiotic treatment of intensive care unit patients, limited data are available on the efficacy of antibiotics on bacterial airway colonization and/or prevention of infections. Therefore, microbiologic responses to antibiotic treatment were evaluated in ventilated patients. Methods: Results of semiquantitative analyses of S. aureus burden in serial endotracheal-aspirate (ETA) samples and VAT/VAP diagnosis were correlated to antibiotic treatment. Minimum inhibitory concentrations of relevant antibiotics using serially collected isolates were evaluated. Results: Forty-eight mechanically ventilated patients who were S. aureus positive by ETA samples and treated with relevant antibiotics for at least 2 consecutive days were included in the study. Vancomycin failed to reduce methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA) burden in the airways. Oxacillin was ineffective for MSSA colonization in approximately 30% of the patients, and responders were typically coadministered additional antibiotics. Despite antibiotic exposure, 15 of the 39 patients (approximately 38%) colonized only by S. aureus and treated with appropriate antibiotic for at least 2 days still progressed to VAP. Importantly, no change in antibiotic susceptibility of S. aureus isolates was observed during treatment. Staphylococcus aureus colonization levels inversely correlated with the presence of normal respiratory flora. Conclusions: Antibiotic treatment is ineffective in reducing S. aureus colonization in the lower airways and preventing VAT or VAP. Staphylococcus aureus is in competition for colonization with the normal respiratory flora. To improve patient outcomes, alternatives to antibiotics are urgently needed.

Pre-emptive antibiotic therapy to reduce ventilator-associated pneumonia: "thinking outside the box".

Mechanically ventilated, intubated patients are at increased risk for tracheal colonization with bacterial pathogens that may progress to heavy bacterial colonization, ventilator-associated tracheobronchitis (VAT), and/or ventilator-associated pneumonia (VAP). Previous studies report that 10 to 30 % of patients with VAT progress to VAP, resulting in increased morbidity and significant acute and chronic healthcare costs. Several natural history studies, randomized, controlled trials, and a meta-analysis have reported antibiotic treatment for VAT can reduce VAP, ventilator days, length of intensive care unit (ICU) stay, and patient morbidity and mortality. We discuss early diagnostic criteria, etiologic agents, and benefits of initiating, early, appropriate intravenous or aerosolized antibiotic(s) to treat VAT and reduce VAP, to improve patient outcomes by reducing lung damage, length of ICU stay, and healthcare costs.

Antibiotic therapy for ventilator-associated tracheobronchitis: a standard of care to reduce pneumonia, morbidity and costs?

PURPOSE OF REVIEW: The present review draws our attention to ventilator-associated tracheobronchitis (VAT) as a distinct clinical entity that has been associated with progression to ventilator-associated pneumonia (VAP) and worse patient outcomes. In contrast to VAP, which has been extensively investigated for over the past 30 years, most VAT studies have been conducted in the past decade. There are ample data which demonstrate that VAT may progress to VAP, have more ventilator days, and have longer ICU stay that may translate into higher healthcare costs. RECENT FINDINGS: The article focuses on the diagnostic criteria for VAT, causative agents, and studies analyzing associations between VAT and patient outcomes in relation to early, appropriate intravenous, and/or aerosolized antibiotic therapy. Aerosolized antibiotic treatment delivered by improved device technology is a novel approach that has proved to be effective for the treatment and eradication of multidrug-resistant bacterial pathogens. Aerosolized antibiotics are effective in decreasing the use of systemic antibiotics, reducing bacterial resistance, and may also facilitate clinical resolution of infection. SUMMARY: Evidence presented in this review supports treatment of VAT with early and appropriate antibiotic therapy as a standard of care to reduce VAP, ventilator days, and duration of ICU stay in high-risk patient population.

α-Hemolysin activity of methicillin-susceptible Staphylococcus aureus predicts ventilator-associated pneumonia.

RATIONALE: Colonization of lower airways by Staphylococcus aureus is a risk factor for the development of ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). However, little is known about the virulence factors of methicillin-sensitive and -resistant S. aureus (MSSA and MRSA) that may influence host colonization and progression to VAT and VAP. OBJECTIVES: We evaluated MRSA and MSSA endotracheal aspirates (ETA) for genotype and α-hemolysin activity in relation to the development of VAT and VAP. METHODS: Serial S. aureus ETA isolates from ventilated patients were analyzed for methicillin resistance, molecular type by Multi-Locus Sequence Typing and spa-typing, and α-hemolysin activity by semiquantitative analysis of hemolysis on sheep blood agar and quantitative measurement of cytolysis of human lung epithelial cells. The virulence of selected strains was assessed in mice by intranasal challenge. MEASUREMENTS AND MAIN RESULTS: We detected S. aureus from ETA samples in a quarter of the 231 ventilated patients analyzed; one-third of them developed VAP. VAP patients (n = 15) were mainly infected by MSSA strains (87%), whereas colonized individuals (n = 18) not progressing to disease mainly carried MRSA strains (68%). MSSA isolates from colonized or VAT patients exhibited significantly lower α-hemolysin activity than those from VAP cases; however, no such relationship was found with MRSA strains. α-Hemolysin activity of S. aureus isolates was predictive for virulence in mouse pneumonia model. CONCLUSIONS: MSSA strains with strong blood agar hemolysis and high α-hemolysin activity are markers for VAP, but not VAT, and might be considered in differential diagnosis and initiation of therapy.

Lyme disease presenting as multiple ischaemic strokes.

A 46-year-old man presented with recurrent left hemiparesis and headache. MRI of brain showed an acute right pontine and subacute right thalamic infarcts and MR angiogram showed multiple intracranial arterial stenoses, suggesting cerebral vasculopathy. There was a cerebrospinal fluid lymphocytic pleocytosis with Borrelia burgdorferi antibodies. Central nervous system Lyme disease occasionally presents with ischaemic strokes; this case is unusual in showing vasculopathy on brain imaging, supporting meningovasculitis as the likely mechanism.

Antibiotic treatment of ventilator-associated tracheobronchitis: to treat or not to treat?

PURPOSE OF REVIEW: To evaluate the data on antimicrobial therapy for ventilator-associated tracheobronchitis (VAT) to prevent ventilator-associated pneumonia (VAP), and its impact on patient outcomes. RECENT FINDINGS: Mechanically ventilated patients are at increased risk for tracheal colonization with bacterial pathogens that may progress to VAT and/or VAP. Previous studies suggest that 10-30% of patients with VAT progress to VAP, which results in increased morbidity but not mortality. Several natural history studies and small randomized controlled trials and a meta-analysis reported that appropriate, pre-emptive antibiotic treatment for VAT reduces VAP, duration of intubation and length of ICU stay. SUMMARY: This review focuses on diagnostic criteria for VAT and VAP, etiologic agents, rationale and benefits of initiating pre-emptive, appropriate antibiotic treatment for VAT to prevent VAP, improve patient outcomes and associated acute and chronic healthcare costs.

Ventilator-associated tracheobronchitis: pre-emptive, appropriate antibiotic therapy recommended.

Nseir and colleagues presented data from a large multicenter study of patients with ventilator-associated tracheobronchitis (VAT), demonstrating that appropriate antibiotic therapy for VAT was an independent predictor for reducing transition to pneumonia (ventilator-associated pneumonia, or VAP). These data added to the growing evidence supporting the use of appropriate antibiotic therapy for VAT as a standard of care to prevent VAP and improve patient outcomes.

Diagnosis of ventilator-associated pneumonia: controversies and working toward a gold standard.

PURPOSE OF REVIEW: The aim is to discuss the clinical, microbiologic, and radiological criteria used in the diagnosis of ventilator-associated pneumonia (VAP), distinguish between ventilator-associated tracheobronchitis (VAT) and VAP, and reconcile the proposed Centers for Disease Control surveillance criteria with clinical practice. RECENT FINDINGS: Numerous ventilator-associated complications (VACs), including VAP and VAT, may occur in critically ill, intubated patients. A variety of definitions for identifying VAP have been proposed, but there is no diagnostic gold standard. The proposed surveillance definition will identify infectious and noninfectious VAC, including VAP and VAT, but this definition may be inadequate for clinical practice. SUMMARY: The clinical characteristics of VAP and VAT are similar and include fever, leukocytosis, and purulent sputum. An infiltrate on chest radiograph is consistent with VAP but lacks diagnostic precision, so it is not a criterion in the proposed surveillance definition and should be interpreted cautiously by clinicians. Microbiologically, quantitative and semiquantitative endotracheal aspirate cultures may be employed to diagnose VAP and VAT. Positive bronchoalveolar lavage and protected specimen brush cultures are useful only for the diagnosis of VAP. Experts should collaborate to develop consensus definitions for VAP and VAT that can be applied in practice.

Ventilator-associated tracheobronchitis and pneumonia: thinking outside the box.

Lower respiratory tract infections in intubated patients include ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). These infections are increasingly caused by multidrug-resistant bacteria, which colonize the patient's oropharynx and enter the lower respiratory tract around the endotracheal tube cuff or through the lumen. Progression of colonization to VAT and, in some patients, to VAP is related to the quantity, types, and virulence of invading bacteria versus containment by host defenses. Diagnostic criteria for VAT and VAP overlap in terms of clinical signs and symptoms, and they share similar microbiologic criteria when endotracheal sputum aspirate samples are used. In addition, the diagnosis of VAP requires a new and persistent infiltrate on a chest radiograph, which may be difficult to assess in critically ill patients, and a significant bacterial culture of a endtotracheal aspirate or bronchoalveolar lavage specimen. Current guidelines for the management of VAP strongly recommend the use of early, appropriate empirical antibiotic therapy based on patient risk factors for multidrug-resistant pathogens. An alternative model focused on VAT, using serial surveillance of endotracheal aspirate specimens to identify multidrug-resistant pathogens and their antibiotic susceptibilities, would allow earlier, targeted antibiotic treatment that could improve outcomes in patients, prevent VAP, and provide an attractive model for clinical research trials.

Health care-associated pneumonia (HCAP): a critical appraisal to improve identification, management, and outcomes--proceedings of the HCAP Summit.

Increasingly, patients are receiving treatment at facilities other than hospitals, including long-term-health care facilities, assisted-living environments, rehabilitation facilities, and dialysis centers. As with hospital environments, nonhospital settings present their own unique risks of pneumonia. Traditionally, pneumonia in these facilities has been categorized as community-acquired pneumonia (CAP). However, the new designation for pneumonias acquired in these settings is health care-associated pneumonia (HCAP), which covers pneumonias acquired in health care environments outside of the traditional hospital setting and excludes hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), and CAP. Although HCAP is currently treated with the same protocols as CAP, recent evidence indicates that HCAP differs from CAP with respect to pathogens and prognosis and, in fact, more closely resembles HAP and VAP. The HCAP Summit convened national infectious disease opinion leaders for the purpose of analyzing current literature, clinical trial data, diagnostic considerations, therapeutic options, and treatment guidelines related to HCAP. After an in-depth analysis of these areas, the infectious disease investigators participating in the summit were surveyed with regard to 10 clinical practice statements. The results were then compared with results of the same survey as completed by 744 Infectious Diseases Society of America members. The similarities and differences between those survey results are the basis of this publication.

Ventilator-associated tracheobronchitis (VAT): questions, answers, and a new paradigm?

Nosocomial lower respiratory tract infections are a common cause of morbidity and mortality in intensive care unit (ICU) patients. Although many studies have investigated the management and prevention of ventilator-associated pneumonia (VAP), few have focused on ventilator-associated tracheobronchitis (VAT). In this issue of Critical Care, Nseir and coworkers present interesting data from a randomized controlled study of antimicrobial therapy for VAT. Patients randomly assigned to antibiotic therapy had more mechanical ventilation-free days (P < 0.001), fewer episodes of VAP (13% versus 47%; P < 0.001), and a lower ICU mortality rate (18% versus 47%; P = 0.05) than those without antibiotic therapy. Although this study has limitations, the data suggest that VAT may be an important risk factor for VAP or overlap with early VAP. More importantly, targeted antibiotic therapy for VAT may improve patient outcomes and become a new paradigm for prevention or early therapy for VAP.

Interaction of daptomycin with two recombinant thromboplastin reagents leads to falsely prolonged patient prothrombin time/International Normalized Ratio results.

A cluster of patients experiencing elevations of International Normalized Ratio without clinical bleeding in temporal association with daptomycin therapy was identified during postmarketing safety surveillance. A common element was the thromboplastin reagent used for the laboratory assay. The present study evaluated the effect of daptomycin on measured prothrombin time using commercially available thromboplastin reagent kits commonly used in the United States. Thirty reagent kits were obtained. Daptomycin was added to pooled normal human plasma samples to achieve final concentrations of 0-200 microg/ml. Quality control ranges were established for each reagent kit using normal and abnormal control plasmas. Triplicate assays of the prothrombin time were performed on the daptomycin-spiked plasma samples using each of the 30 kits. The activated partial thromboplastin time and thrombin time were also assessed. Statistical comparisons of interest were performed using analysis of variance with the Bonferroni t-test for multiple comparisons; alpha = 0.05 was used. Addition of daptomycin to human plasma samples dose-dependently prolonged measured prothrombin times when two recombinant thromboplastin reagents were utilized. The findings were statistically and clinically significant. No clinically meaningful effect was observed with the other reagents. The activated partial thromboplastin time and thrombin time were not affected. Prolonged International Normalized Ratio patient values were an artifact caused by the interaction of daptomycin with the in-vitro prothrombin time test reagent; an in-vivo anticoagulant effect was not observed. Healthcare providers should consider a possible drug-laboratory test interaction if prolonged prothrombin time or elevated International Normalized Ratio values are observed in patients receiving daptomycin.

Silver-coated endotracheal tubes and incidence of ventilator-associated pneumonia: the NASCENT randomized trial.

CONTEXT: Ventilator-associated pneumonia (VAP) causes substantial morbidity. A silver-coated endotracheal tube has been designed to reduce VAP incidence by preventing bacterial colonization and biofilm formation. OBJECTIVE: To determine whether a silver-coated endotracheal tube would reduce the incidence of microbiologically confirmed VAP. DESIGN, SETTING, AND PARTICIPANTS: Prospective, randomized, single-blind, controlled study conducted in 54 centers in North America. A total of 9417 adult patients (> or = 18 years) were screened between 2002 and 2006. A total of 2003 patients expected to require mechanical ventilation for 24 hours or longer were randomized. INTERVENTION: Patients were assigned to undergo intubation with 1 of 2 high-volume, low-pressure endotracheal tubes, similar except for a silver coating on the experimental tube. MAIN OUTCOME MEASURES: Primary outcome was VAP incidence based on quantitative bronchoalveolar lavage fluid culture with 10(4) colony-forming units/mL or greater in patients intubated for 24 hours or longer. Other outcomes were VAP incidence in all intubated patients, time to VAP onset, length of intubation and duration of intensive care unit and hospital stay, mortality, and adverse events. RESULTS: Among patients intubated for 24 hours or longer, rates of microbiologically confirmed VAP were 4.8% (37/766 patients; 95% confidence interval [CI], 3.4%-6.6%) in the group receiving the silver-coated tube and 7.5% (56/743; 95% CI, 5.7%-9.7%) (P = .03) in the group receiving the uncoated tube (all intubated patients, 3.8% [37/968; 95% CI, 2.7%-5.2%] and 5.8% [56/964; 95% CI, 4.4%-7.5%] [P = .04]), with a relative risk reduction of 35.9% (95% CI, 3.6%-69.0%; all intubated patients, 34.2% [95% CI, 1.2%-67.9%]). The silver-coated endotracheal tube was associated with delayed occurrence of VAP (P = .005). No statistically significant between-group differences were observed in durations of intubation, intensive care unit stay, and hospital stay; mortality; and frequency and severity of adverse events. CONCLUSION: Patients receiving a silver-coated endotracheal tube had a statistically significant reduction in the incidence of VAP and delayed time to VAP occurrence compared with those receiving a similar, uncoated tube. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00148642.

Endothelial function in HIV-infected persons.

BACKGROUND: Several reports have suggested an increased risk of coronary disease in human immunodeficiency virus (HIV)-infected patients receiving protease inhibitors (PIs). Impaired endothelium-dependent vasodilation is a putative surrogate marker of coronary atherosclerotic disease. METHODS: The present study evaluated the effect of HIV infection and antiretroviral treatment on endothelial vasomotor function, by assessing brachial artery flow-mediated dilation (FMD). A total of 75 HIV-infected patients were compared with 223 control subjects who were presumed to be HIV uninfected. RESULTS: HIV-infected patients had significantly impaired FMD, compared with control subjects (mean +/- SD, 7.3% +/- 4.4% vs. 11.1% +/- 6.3%; P < .0001). When adjustments were made for smoking status, sex, and body mass index, the difference between the 2 groups remained statistically significant (P < .01). In a cross-sectional analysis of the HIV-infected patients, we found significant associations between FMD and current injection drug use, hazardous drinking, HIV load, and alpha-high-density lipoprotein triglyceride levels, but not PI therapy. In a multivariate analysis, only current injection drug use and a lower alpha-high-density lipoprotein triglyceride level were significantly associated with FMD. CONCLUSIONS: HIV-infected patients have significant impairment of endothelial function, and this impairment is worse among those with elevated levels of HIV replication, particularly injection drug users.

Preventing ventilator-associated pneumonia in adults: sowing seeds of change.

Ventilator-associated pneumonia (VAP), a major cause of ICU infection, results in high morbidity, mortality, and health-care costs. Multiple risk factors for VAP involve complex host factors and ubiquitous pathogens that require several different types of prevention strategies. Prevention efforts should focus on reducing bacterial colonization, and limiting aspiration, antibiotic exposure, and use of invasive devices. Although evidence-based prevention guidelines are available, they are lengthy, often ignored, and not implemented. New insights into the barriers to implementation of effective prevention programs are emerging. This article provides highlights from recent guidelines and publications discussing VAP prevention strategies and examines barriers to their implementation. Prevention and implementation of cost-effective strategies to reduce risk and improve patient outcomes should be prioritized. Clearly, prevention programs should be population specific and may vary among hospitals, but a multidisciplinary prevention team led by a "champion" is recommended to help set priorities, benchmarking goals, analyze data, and sow the seeds of change for risk reduction.

Prophylaxis for human immunodeficiency virus-related Pneumocystis carinii pneumonia: using simulation modeling to inform clinical guidelines.

BACKGROUND: Human immunodeficiency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART) have experienced a dramatic decrease in Pneumocystis carinii pneumonia (PCP), necessitating reassessment of clinical guidelines for prophylaxis. METHODS: A simulation model of HIV infection was used to estimate the lifetime costs and quality-adjusted life expectancy (QALE) for alternative CD4 cell count criteria for stopping primary PCP prophylaxis in patients with CD4 cell count increases receiving HAART and alternative agents for second-line PCP prophylaxis in those intolerant of trimethoprim-sulfamethoxazole (TMP/SMX). The target population was a cohort of HIV-infected patients in the United States with initial CD4 cell counts of 350/microL who began PCP prophylaxis after their first measured CD4 lymphocyte count less than 200/microL. Data were from randomized controlled trials and other published literature. RESULTS: For patients with CD4 cell count increases during HAART, waiting to stop prophylaxis until the first observed CD4 cell count was greater than 300/microL prevented 9 additional cases per 1000 patients and cost $9400 per quality-adjusted life year (QALY) gained compared with stopping prophylaxis at 200/microL. For patients intolerant of TMP/SMX, using dapsone increased QALE by 2.7 months and cost $4500 per QALY compared with no prophylaxis. Using atovaquone rather than dapsone provided only 3 days of additional QALE and cost more than $1.5 million per QALY. CONCLUSIONS: Delaying discontinuation of PCP prophylaxis until the first observed CD4 cell count greater than 300/microL is cost-effective and provides an explicit "PCP prophylaxis stopping criterion." In TMP/SMX-intolerant patients, dapsone is more cost-effective than atovaquone.

Hepatitis C virus and human immunodeficiency virus coinfection in an urban population: low eligibility for interferon treatment.

One hundred eighty human immunodeficiency virus (HIV)- and hepatitis C virus (HCV)-coinfected patients were prospectively evaluated for suitability for interferon and ribavirin therapy. Of the 149 patients with chronic HCV infection who completed the evaluation, 44 (30%) were eligible for treatment and 105 (70%) were ineligible, with the main barriers being missed clinic visits, active psychiatric illness, active drug or alcohol use, decompensated liver disease, or medical illness.

Health-related quality of life of patients with HIV disease: impact of hepatitis C coinfection.

Health-related quality of life (HRQOL) is diminished in patients infected with both hepatitis C virus (HCV) and human immunodeficiency virus (HIV), but the effect of HIV/HCV coinfection on HRQOL is unknown. We compared the HRQOL of urban HIV/HCV coinfected patients with that of patients infected with either HCV or HIV alone. We then compared the 3 groups with a US population sample, adjusting for demographic characteristics. HRQOL for the group of HIV/HCV coinfected patients was statistically similar to that of HRQOL in patients with either HCV or HIV alone, but the 3 groups had a significantly decreased HRQOL than did the adjusted US population. Using multivariate techniques, we determined that age, unemployment, injection drug use, and depression were associated with impaired HRQOL. These findings underscore the importance of a multidisciplinary approach to the treatment of these patient populations.