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

Biomarkers in pulmonary infections: a clinical approach

Severe acute respiratory infections, such as community-acquired pneumonia, hospital-acquired pneumonia, and ventilator-associated pneumonia, constitute frequent and lethal pulmonary infections in the intensive care unit (ICU). Despite optimal management with early appropriate empiric antimicrobial therapy and adequate supportive care, mortality remains high, in part attributable to the aging, growing number of comorbidities, and rising rates of multidrug resistance pathogens. Biomarkers have the potential to offer additional information that may further improve the management and outcome of pulmonary infections. Available pathogen-specific biomarkers, for example, Streptococcus pneumoniae urinary antigen test and galactomannan, can be helpful in the microbiologic diagnosis of pulmonary infection in ICU patients, improving the timing and appropriateness of empiric antimicrobial therapy since these tests have a short turnaround time in comparison to classic microbiology. On the other hand, host-response biomarkers, for example, C-reactive protein and procalcitonin, used in conjunction with the clinical data, may be useful in the diagnosis and prediction of pulmonary infections, monitoring the response to treatment, and guiding duration of antimicrobial therapy. The assessment of serial measurements overtime, kinetics of biomarkers, is more informative than a single value. The appropriate utilization of accurate pathogen-specific and host-response biomarkers may benefit clinical decision-making at the bedside and optimize antimicrobial stewardship.

Cefiderocol (Fetroja) as a Treatment for Hospital-Acquired Pneumonia

With increasing resistance to conventional antibiotic treatments, especially among gram-negative bacilli, the search for new antibiotics has become critical on a global scale. Among infections with multidrug-resistant bacteria is hospital-acquired pneumonia (HAP), which is nosocomial pneumonia in patients who have been hospitalized for more than 48 hours. HAP carries a high mortality rate and continues to be a challenge with regard to adequate treatment. The typical multidrug-resistant gram negatives found in HAP include Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii. Many new antibiotics have been studied and tested against these pathogens as possible solutions, and the search continues. Cefiderocol, a novel siderophore cephalosporin, is effective against these pathogens. Cefiderocol is an iron-chelating agent that makes use of iron pumps on the membrane of bacteria via a catechol moiety on the C3 side chain of the molecule. This allows for easy access into the cytoplasm, where it can inhibit peptidoglycan synthesis by binding to penicillin-binding proteins. Cefiderocol displays linear pharmacokinetics and is mainly excreted through the kidneys. It is well tolerated in healthy individuals but may need adjustments of dosage in patients with impaired renal function. Studies have shown that both healthy subjects and those with impaired renal function experienced some adverse effects, including nausea, diarrhea, abdominal pain, and increased creatinine kinase; however, these adverse effects were limited and experienced in placebo groups. It has demonstrated efficacy in treating infections caused by many multidrug-resistant gram-negative pathogens and has demonstrated high stability against many classes of b-lactamases. There have been multiple phase 3 trials, such as the CREDIBLE-CR trial and the APEKS-NP trial, that demonstrated efficacy in treated nosocomial pneumonia caused by multidrug-resistant gram negatives, such as carbapenem-resistant Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa, compared to the best available treatment. While clinical data remain limited, a few studies are showing clinical efficacy and few adverse effects. Cefiderocol demonstrated effectivity in treating multidrug-resistant gram-negative pneumonia in patients with multiple comorbidities, such as chronic kidney disease, chronic-obstructive pulmonary disease, and diabetes mellitus. Cefiderocol shows promise as a novel antimicrobial agent in treating multidrug-resistant gram-negative in HAP.

Metagenomics for the microbiological diagnosis of hospital-acquired pneumonia and ventilator-associated pneumonia (HAP/VAP) in intensive care unit (ICU): a proof-of-concept study

BACKGROUND

Hospital-acquired and ventilator-associated-pneumonia (HAP/VAP) are one of the most prevalent health-care associated infections in the intensive care unit (ICU). Culture-independent methods were therefore developed to provide faster route to diagnosis and treatment. Among these, metagenomic next-generation sequencing (mNGS) has shown considerable promise.

METHODS

This proof-of-concept study describes the technical feasibility and evaluates the clinical validity of the mNGS for the detection and characterization of the etiologic agents causing hospital-acquired and ventilator-associated pneumonia. We performed a prospective study of all patients with HAP/VAP hospitalized in our intensive care unit for whom a bronchoalveolar lavage (BAL) was performed between July 2017 and November 2018. We compared BAL fluid culture and mNGS results of these patients.

RESULTS

A total of 32 BAL fluids were fully analyzed. Of these, 22 (69%) were positive by culture and all pathogens identified were also reported by mNGS. Among the culture-positive BAL samples, additional bacterial species were revealed by mNGS for 12 patients, raising the issue of their pathogenic role (colonization versus coinfection). Among BALF with culture-negative test, 5 were positive in mNGS test.

CONCLUSIONS

This study revealed concordant results for pneumonia panel pathogens between mNGS and culture-positive tests and identified additional pathogens potentially implicated in pneumonia without etiologic diagnosis by culture. mNGS has emerged as a promising methodology for infectious disease diagnoses to support conventional methods. Prospective studies with real-time mNGS are warranted to examine the impact on antimicrobial decision-making and clinical outcome.

[Antibiotic treatment of community-acquired and hospital-acquired pneumonia]

Community-acquired and nosocomial bacterial pneumonia are among the most common infectious diseases in Germany. Knowledge of possible pathogens and therapeutic implications thereof are essential to be able to provide adequate, differentiated antimicrobial therapy with the appropriate drugs, form of application, dose, and duration. New diagnostics that include multiplex polymerase chain reaction, correct interpretation of the biomarker procalcitonin, and treatment of multidrug-resistant bacteria are becoming increasingly import.

New Antibiotics for Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) represent one of the most common hospital-acquired infections, carrying a significant morbidity and risk of mortality. Increasing antibiotic resistance among the common bacterial pathogens associated with HAP and VAP, especially Enterobacterales and nonfermenting gram-negative bacteria, has made the choice of empiric treatment of these infections increasingly challenging. Moreover, failure of initial empiric therapy to cover the causative agents associated with HAP and VAP has been associated with worse clinical outcomes. This review provides an overview of antibiotics newly approved or in development for the treatment of HAP and VAP. The approved antibiotics include ceftobiprole, ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, and cefiderocol. Their major advantages include their high activity against multidrug-resistant gram-negative pathogens.

Multicentre evaluation of two multiplex PCR platforms for the rapid microbiological investigation of nosocomial pneumonia in UK ICUs: the INHALE WP1 study

BACKGROUND

Culture-based microbiological investigation of hospital-acquired or ventilator-associated pneumonia (HAP or VAP) is insensitive, with aetiological agents often unidentified. This can lead to excess antimicrobial treatment of patients with susceptible pathogens, while those with resistant bacteria are treated inadequately for prolonged periods. Using PCR to seek pathogens and their resistance genes directly from clinical samples may improve therapy and stewardship.

METHODS

Surplus routine lower respiratory tract samples were collected from intensive care unit patients about to receive new or changed antibiotics for hospital-onset lower respiratory tract infections at 15 UK hospitals. Testing was performed using the BioFire FilmArray Pneumonia Panel (bioMérieux) and Unyvero Pneumonia Panel (Curetis). Concordance analysis compared machine and routine microbiology results, while Bayesian latent class (BLC) analysis estimated the sensitivity and specificity of each test, incorporating information from both PCR panels and routine microbiology.

FINDINGS

In 652 eligible samples; PCR identified pathogens in considerably more samples compared with routine microbiology: 60.4% and 74.2% for Unyvero and FilmArray respectively vs 44.2% by routine microbiology. PCR tests also detected more pathogens per sample than routine microbiology. For common HAP/VAP pathogens, FilmArray had sensitivity of 91.7%-100.0% and specificity of 87.5%-99.5%; Unyvero had sensitivity of 50.0%-100.0%%, and specificity of 89.4%-99.0%. BLC analysis indicated that, compared with PCR, routine microbiology had low sensitivity, ranging from 27.0% to 69.4%.

INTERPRETATION

Conventional and BLC analysis demonstrated that both platforms performed similarly and were considerably more sensitive than routine microbiology, detecting potential pathogens in patient samples reported as culture negative. The increased sensitivity of detection realised by PCR offers potential for improved antimicrobial prescribing.

Which Biomarkers Can Be Used as Diagnostic Tools for Infection in Suspected Sepsis?

The diagnosis of infection in patients with suspected sepsis is frequently difficult to achieve with a reasonable degree of certainty. Currently, the diagnosis of infection still relies on a combination of systemic manifestations, manifestations of organ dysfunction, and microbiological documentation. In addition, the microbiologic confirmation of infection is obtained only after 2 to 3 days of empiric antibiotic therapy. These criteria are far from perfect being at least in part responsible for the overuse and misuse of antibiotics, in the community and in hospital, and probably the main drive for antibiotic resistance. Biomarkers have been studied and used in several clinical settings as surrogate markers of infection to improve their diagnostic accuracy as well as in the assessment of response to antibiotics and in antibiotic stewardship programs. The aim of this review is to provide a clear overview of the current evidence of usefulness of biomarkers in several clinical scenarios, namely, to diagnose infection to prescribe antibiotics, to exclude infection to withhold antibiotics, and to identify the causative pathogen to target antimicrobial treatment. In recent years, new evidence with "old" biomarkers, like C-reactive protein and procalcitonin, as well as new biomarkers and molecular tests, as breathomics or bacterial DNA identification by polymerase chain reaction, increased markedly in different areas adding useful information for clinical decision making at the bedside when adequately used. The recent evidence shows that the information given by biomarkers can support the suspicion of infection and pathogen identification but also, and not less important, can exclude its diagnosis. Although the ideal biomarker has not yet been found, there are various promising biomarkers that represent true evolutions in the diagnosis of infection in patients with suspected sepsis.

Protocol for an international, multicentre, prospective, observational study of nosocomial pneumonia in intensive care units: the PneumoINSPIRE study

Background: Nosocomial pneumonia in the critical care setting is associated with increased morbidity, significant crude mortality rates and high health care costs. Ventilator-associated pneumonia represents about 80% of nosocomial pneumonia cases in intensive care units (ICUs). Wide variance in incidence of nosocomial pneumonia and diagnostic techniques used has been reported, while successful treatment remains complex and a matter of debate. Objective: To describe the epidemiology, diagnostic strategies and treatment modalities for nosocomial pneumonia in contemporary ICU settings across multiple countries around the world. Design, setting and patients: PneumoINSPIRE is a large, multinational, prospective cohort study of adult ICU patients diagnosed with nosocomial pneumonia. Participating ICUs from at least 20 countries will collect data on 10 or more consecutive ICU patients with nosocomial pneumonia. Site-specific information, including hospital policies on antibiotic therapy, will be recorded along with patient-specific data. Variables that will be explored include: aetiology and antimicrobial resistance patterns, treatment-related parameters (including time to initiation of antibiotic therapy, and empirical antibiotic choice, dose and escalation or de-escalation), pneumonia resolution, ICU and hospital mortality, and risk factors for unfavourable outcomes. The concordance of ventilator-associated pneumonia diagnosis with accepted definitions will also be assessed. Results and conclusions: PneumoINSPIRE will provide valuable information on current diagnostic and management practices relating to ICU nosocomial pneumonia, and identify research priorities in the field. Trial registration:ClinicalTrials.gov identifier NCT02793141.

Emergence of Nosocomial Pneumonia Caused by Colistin-Resistant Escherichia coli in Patients Admitted to Chest Intensive Care Unit

(1) Background: Colistin is a last-resort antibiotic used in treating multidrug-resistant Gram-negative infections. The growing emergence of colistin resistance in Escherichia coli (E. coli) represents a serious health threat, particularly to intensive care unit (ICU) patients. (2) Methods: In this work, we investigated the emergence of colistin resistance in 140 nosocomial E. coli isolated from patients with pneumonia and admitted to the chest ICU over 36 months. Virulence and resistance-related genes and E. coli pathotypes in colistin-resistant and colistin-sensitive isolates were determined. (3) Results: Colistin resistance was observed in 21/140 (15%) of the nosocomial E. coli isolates. The MIC₅₀ of the resistant strains was 4 mg/L, while MIC₉₀ was 16 mg/L. Colistin-resistant isolates were also co-resistant to amoxicillin, amoxicillin/clavulanic, aztreonam, ciprofloxacin, and chloramphenicol. The mechanism of colistin resistance was represented by the presence of mcr-1 in all resistant strains. Respectively, 42.9% and 36.1% of colistin-resistant and colistin-sensitive groups were extended-spectrum β-lactamase (ESBL) producers, while 23.8% and 21% were metallo β-lactamase (MBL) producers. bla_TEM-type was the most frequently detected ESBL gene, while bla_IMP-type was the most common MBL in both groups. Importantly, most resistant strains showed a significantly high prevalence of astA (76.2%), aggR (76.2%), and pic (52.4%) virulence-related genes. Enteroaggregative E. coli (76%) was the most frequently detected genotype among the colistin-resistant strains. (4) Conclusion: The high colistin resistance rate observed in E. coli strains isolated from patients with nosocomial pneumonia in our university hospital is worrisome. These isolates carry different drug resistance and virulence-related genes. Our results indicate the need for careful monitoring of colistin resistance in our university hospital. Furthermore, infection control policies restricting the unnecessary use of extended-spectrum cephalosporins and carbapenems are necessary.

Short-Term Effects of Appropriate Empirical Antimicrobial Treatment with Ceftolozane/Tazobactam in a Swine Model of Nosocomial Pneumonia

The rising frequency of multidrug-resistant and extensively drug-resistant (MDR/XDR) pathogens is making more frequent the inappropriate empirical antimicrobial therapy (IEAT) in nosocomial pneumonia, which is associated with increased mortality. We aim to determine the short-term benefits of appropriate empirical antimicrobial treatment (AEAT) with ceftolozane/tazobactam (C/T) compared with IEAT with piperacillin/tazobactam (TZP) in MDR Pseudomonas aeruginosa pneumonia. Twenty-one pigs with pneumonia caused by an XDR P. aeruginosa strain (susceptible to C/T but resistant to TZP) were ventilated for up to 72 h. Twenty-four hours after bacterial challenge, animals were randomized to receive 2-day treatment with either intravenous saline (untreated) or 25 to 50 mg of C/T per kg body weight (AEAT) or 200 to 225 mg of TZP per kg (IEAT) every 8 h. The primary outcome was the P. aeruginosa burden in lung tissue and the histopathology injury. P. aeruginosa burden in tracheal secretions and bronchoalveolar lavage (BAL) fluid, the development of antibiotic resistance, and inflammatory markers were secondary outcomes. Overall, P. aeruginosa lung burden was 5.30 (range, 4.00 to 6.30), 4.04 (3.64 to 4.51), and 4.04 (3.05 to 4.88) log₁₀CFU/g in the untreated, AEAT, and IEAT groups, respectively (P = 0.299), without histopathological differences (P = 0.556). In contrast, in tracheal secretions (P < 0.001) and BAL fluid (P = 0.002), bactericidal efficacy was higher in the AEAT group. An increased MIC to TZP was found in 3 animals, while resistance to C/T did not develop. Interleukin-1β (IL-1β) was significantly downregulated by AEAT in comparison to other groups (P = 0.031). In a mechanically ventilated swine model of XDR P. aeruginosa pneumonia, appropriate initial treatment with C/T decreased respiratory secretions' bacterial burden, prevented development of resistance, achieved the pharmacodynamic target, and may have reduced systemic inflammation. However, after only 2 days of treatment, P. aeruginosa tissue concentrations were moderately affected.

Trauma and Antimicrobial Resistance Are Independent Predictors of Inadequate Empirical Antimicrobial Treatment of Ventilator-Associated Pneumonia in Critically Ill Patients

Background: We aimed to assess independent risk factors for inadequate initial antimicrobial treatment (IAT) in critically ill patients with ventilator-associated pneumonia (VAP) treated in intensive care units (ICU) and to determine whether IAT is associated with adverse outcomes in patients with VAP. Patients and Methods: A prospective cohort study was performed and included 152 patients with VAP treated in an ICU for more than 48 hours. The main outcomes of interest were all-cause ICU mortality and VAP-related mortality. Other outcomes considered were: intra-hospital mortality, VAP-related sepsis, relapse, re-infection, length of stay in ICU (ICU LOS), and number of days on mechanical ventilation (MV). Results: One-third of patients (35.5%) received inadequate antimicrobial therapy. Trauma (odds ratio [OR], 3.55; 95% confidence interval [CI], 1.25-10.06) and extensively drug-resistant (XDR) causative agent (OR, 3.09; 95% CI, 1.23-7.74) were independently associated with inadequate IAT. Inadequate IAT was associated with a higher mortality rate (OR, 3.08; 95% CI, 1.30-7.26), VAP-related sepsis (OR, 2.39; 95% CI, 1.07-5.32), relapse (OR, 3.25; 95% CI, 1.34-7.89), re-infection (OR, 6.06; 95% CI, 2.48-14.77), and ICU LOS (β 4.65; 95% CI, 0.93-8.36). Acinetobacter spp., Pseudomonas aeruginosa and Klebsiella/Enterobacter spp. were the most common bacteria in patients with IAT and those with adequate antimicrobial therapy. Conclusions: This study demonstrated that inadequate IAT is associated with a higher risk of the majority of adverse outcomes in patients with VAP treated in ICUs. Trauma and XDR strains of bacteria are independent predictors of inadequate IAT of VAP in critically ill patients.

Performance and comparison of assessment models to predict 30-day mortality in patients with hospital-acquired pneumonia

BACKGROUND

Hospital-acquired pneumonia (HAP) is the most common hospital-acquired infection in China with substantial morbidity and mortality. But no specific risk assessment model has been well validated in patients with HAP. The aim of this study was to investigate the published risk assessment models that could potentially be used to predict 30-day mortality in HAP patients in non-surgical departments.

METHODS

This study was a single-center, retrospective study. In total, 223 patients diagnosed with HAP from 2012 to 2017 were included in this study. Clinical and laboratory data during the initial 24 hours after HAP diagnosis were collected to calculate the pneumonia severity index (PSI); consciousness, urea nitrogen, respiratory rate, blood pressure, and age ≥65 years (CURB-65); Acute Physiology and Chronic Health Evaluation II (APACHE II); Sequential Organ Failure Assessment (SOFA); and Quick Sequential Organ Failure Assessment (qSOFA) scores. The discriminatory power was tested by constructing receiver operating characteristic (ROC) curves, and the areas under the curve (AUCs) were calculated.

RESULTS

The all-cause 30-day mortality rate was 18.4% (41/223). The PSI, CURB-65, SOFA, APACHE II, and qSOFA scores were significantly higher in non-survivors than in survivors (all P < 0.001). The discriminatory abilities of the APACHE II and SOFA scores were better than those of the CURB-65 and qSOFA scores (ROC AUC: APACHE II vs. CURB-65, 0.863 vs. 0.744, Z = 3.055, P = 0.002; APACHE II vs. qSOFA, 0.863 vs. 0.767, Z = 3.017, P = 0.003; SOFA vs. CURB-65, 0.856 vs. 0.744, Z = 2.589, P = 0.010; SOFA vs. qSOFA, 0.856 vs. 0.767, Z = 2.170, P = 0.030). The cut-off values we defined for the SOFA, APACHE II, and qSOFA scores were 4, 14, and 1.

CONCLUSIONS

These results suggest that the APACHE II and SOFA scores determined during the initial 24 h after HAP diagnosis may be useful for the prediction of 30-day mortality in HAP patients in non-surgical departments. The qSOFA score may be a simple tool that can be used to quickly identify severe infections.

Feasibility of informing syndrome-level empiric antibiotic recommendations using publicly available antibiotic resistance datasets

Background: Antibiotics are often prescribed empirically to treat infection syndromes before causative bacteria and their susceptibility to antibiotics are identified. Guidelines on empiric antibiotic prescribing are key to effective treatment of infection syndromes, and need to be informed by likely bacterial aetiology and antibiotic resistance patterns. We aimed to create a clinically-relevant composite index of antibiotic resistance for common infection syndromes to inform recommendations at the national level.

Methods: To create our index, we used open-access antimicrobial resistance (AMR) surveillance datasets, including the ECDC Surveillance Atlas, CDDEP ResistanceMap, WHO GLASS and the newly-available Pfizer ATLAS dataset. We integrated these with data on aetiology of common infection syndromes, existing empiric prescribing guidelines, and pricing and availability of antibiotics.

Results:  The ATLAS dataset covered many more bacterial species (287) and antibiotics (52) than other datasets (ranges = 8-11 and 16-32 respectively), but had a similar number of samples per country per year. Using these data, we were able to make empiric prescribing recommendations for bloodstream infection, pneumonia and cellulitis/skin abscess in up to 44 countries. There was insufficient data to make national-level recommendations for the other six syndromes investigated. Results are presented in an interactive web app, where users can visualise underlying resistance proportions to first-line empiric antibiotics for infection syndromes and countries of interest.

Conclusions: We found that whilst the creation of a composite resistance index for empiric antibiotic therapy was technically feasible, the ATLAS dataset in its current form can only inform on a limited number of infection syndromes. Other open-access AMR surveillance datasets are largely limited to bloodstream infection specimens and cannot directly inform treatment of other syndromes. With improving availability of international AMR data and better understanding of infection aetiology, this approach may prove useful for informing empiric prescribing decisions in settings with limited local AMR surveillance data

Ventilator-associated pneumonia in patients with cerebral hemorrhage: Impact on mortality and microbiological characterization

Ventilator-associated pneumonia (VAP) is a major complication among critically ill patients who depend on mechanical ventilation. Few reports have focused on intracerebral hemorrhage patients with VAP. Our main objective was to investigate the bacteria distribution characteristics and the impact of ventilator-associated pneumonia mortality in critical cerebral hemorrhage patients. This retrospective study included 89 cases of cerebral hemorrhage patients with VAP admitted to the ICU of Huashan Hospital. We used the chi-square test to compare qualitative variables and Student's t-test to compare means between groups of normally distributed quantitative variables. Multiple logistic regression analysis was used to assess mortality-independent predictors in the ICU. A total of 42% patients with cerebral hemorrhage were diagnosed with VAP in the ICU during the study period, and the mortality rate was 18%. Acinetobacter baumannii (n=58), Klebsiella pneumoniae (n=52), and Pseudomonas aeruginosa (n=21) were the most common pathogenic bacteria. Blood volume >30ml, tracheal ventilation mode and head of bed elevation were independent factors associated with increased mortality. Glasgow Coma Scale (GCS), Acute Physiology and Chronic Health Evaluation II (APACHE II) score and the time from bleeding to intubation were other potentially important factors. While the number of infecting bacteria may not be directly related to death, it can increase antibiotic consumption and length of intensive care unit (ICU) stays. Blood volume >30ml, tracheal ventilation mode and head of bed elevation were directly related to the death of critical cerebral hemorrhage patients with ventilator-associated pneumonia.

Gradient diffusion antibiogram used directly on bronchial aspirates for a rapid diagnosis of ventilator-associated pneumonia

Background

In patients with suspected ventilator-associated pneumonia, a rapid etiological diagnosis is crucial as incorrect or delayed treatment in the first few hours leads to a worse prognosis and a higher mortality rate. This study examines the efficacy of a rapid antibiogram on bronchial aspirates in patients with suspected ventilator-associated pneumonia (VAP).

Methods

The direct gradient diffusion susceptibility testing method (GDM) on respiratory samples was compared with a standard broth microdilution method (BMD) after quantitative cultures in patients with suspicion of VAP. Samples were preselected by Gram staining (for good quality microbiological samples with a predominant single bacterial morphotype). The antibiotics tested were ceftazidime, ceftobiprole, ceftolozane-tazobactam, meropenem, doripenem, and tedizolid.

Results

Over a 16-month study period, 445 bronchial aspirate samples were selected from 1376 samples received at our laboratory from 672 adult patients. By direct plating on Mueller-Hinton agar, we recovered 504 (95.5%) of the 528 microorganisms identified by the standard semiquantitative method. Antimicrobial susceptibility testing by GDM was compared with the BMD method in 472 strains (216 Enterobacteriaceae, 138 P. aeruginosa and 118 S. aureus.) and 1652 individual microorganism-antimicrobial agent combinations. There was total agreement between both methods in 98% of combinations. The Kappa index between both techniques was excellent (over 80%). There was only one potential major error for P. aeruginosa susceptibility to ceftazidime.

Conclusions

The six GDM strips directly placed on plated bronchial aspirates obtained from patients with a suspicion of VAP provided accurate and reliable susceptibility results within 24 h.

Clinical Diagnosis of Infection in Surgical Intensive Care Unit: You're Not as Good as You Think!

Background: Because of the everincreasing costs and the complexity of institutional medical reimbursement policies, the necessity for extensive laboratory work-up of potentially infected patients has come into question. We hypothesized that intensivists are able to differentiate between infected and non-infected patients clinically, without the need to pan-culture, and are able to identify the location of the infection clinically in order to administer timely and appropriate treatment. Methods: Data collected prospectively on critically ill patients suspected of having an infection in the surgical intensive care unit (SICU) was obtained over a six-month period in a single tertiary academic medical center. Objective evidence of infection derived from laboratory or imaging data was compared with the subjective answers of the three most senior physicians' clinical diagnoses. Results: Thirty-nine critically ill surgical patients received 52 work-ups for suspected infections on the basis of signs and symptoms (e.g., fever, altered mental status). Thirty patients were found to be infected. Clinical diagnosis differentiated infected and non-infected patients with only 61.5% accuracy (sensitivity 60.3%; specificity 64.4%; p = 0.0049). Concordance between physicians was poor (κ = 0.33). Providers were able to predict the infectious source correctly only 60% of the time. Utilization of culture/objective data and SICU antibiotic protocols led to overall 78% appropriate initiation of antibiotics compared with 48% when treatment was based on clinical evaluation alone. Conclusion: Clinical diagnosis of infection is difficult, inaccurate, and unreliable in the absence of culture and sensitivity data. Infection suspected on the basis of signs and symptoms should be confirmed via objective and thorough work-up.

Feasibility of informing syndrome-level empiric antibiotic recommendations using publicly available antibiotic resistance datasets

Background: Antibiotics are most often prescribed empirically, meaning that they are used to treat infection syndromes prior to identification of the causative bacteria and their susceptibility to antibiotics. The effectiveness of antibiotic therapies is now compromised by the emergence and spread of antibiotic-resistant bacteria. Guidelines on empiric antibiotic therapy are a key component of effective clinical care for infection syndromes, as treatment needs to be informed by knowledge of likely aetiology and bacterial resistance patterns. Methods: We used open-access antimicrobial resistance (AMR) surveillance datasets, including the newly available ATLAS dataset from Pfizer, to derive a composite index of antibiotic resistance for common infection syndromes. Results: We developed a framework that integrated data on antibiotic prescribing guidelines, aetiology of infections, access to and cost of antibiotics, with antibiotic susceptibilities from global AMR surveillance datasets to create an empirical prescribing index. The results are presented in an interactive web app to allow users to visualise underlying resistance rates to first-line empiric antibiotics for their infection syndromes and countries of interest. Conclusions: We found that whilst an index for empiric antibiotic therapy based on resistance data can technically be created, the ATLAS dataset in its current form can only inform on a limited number of infection syndromes. Other open-access AMR surveillance datasets (ECDC Surveillance Atlas, CDDEP ResistanceMap and WHO GLASS datasets) are largely limited to bacteraemia-derived specimens and cannot directly inform treatment of other infection syndromes. With improving data availability on international rates of AMR and better understanding of infection aetiology, our approach may prove useful for informing empiric prescribing decisions in settings with limited local AMR surveillance data. Syndrome-level resistance could be a more clinically relevant measure of resistance to inform on the appropriateness of empiric antibiotic therapies at the country-level.

Controversies and advances in the management of ventilator associated pneumonia

INTRODUCTION

Although national surveillance data suggests that the incidence of ventilator associated pneumonia (VAP) is down-trending, it remains one of the most commonly encountered hospital acquired infections in the United States and worldwide. Its association with increased healthcare costs and worsened patient outcomes warrants continued effort to improve the care of patients with VAP. Areas covered: The increasing prevalence of multi-drug resistant bacteria further drives the need to explore advances in diagnostic and treatment options. In this review, controversies pertaining to the definition and diagnosis of VAP as well as empiric treatment strategies will be discussed along with several developments related to rapid microbiologic testing methods and the use of non-traditional antimicrobial agents. Expert commentary: The application of rapid diagnostic techniques to identify microbial pathogens is perhaps one of the most impactful advancements in the treatment of serious nosocomial infections. This technology has the potential to reduce inappropriate initial antimicrobial therapy, unnecessary antimicrobial exposure, and mortality in patients with VAP. In addition, the anticipated approval of new antimicrobial agents within the next several years will provide a much-needed expansion of available treatment options in an era of growing antimicrobial resistance.

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

Ventilator-associated pneumonia: the influence of bacterial resistance, prescription errors, and de-escalation of antimicrobial therapy on mortality rates

Ventilator-associated pneumonia is the most prevalent nosocomial infection in intensive care units and is associated with high mortality rates (14–70%).

Aim

This study evaluated factors influencing mortality of patients with Ventilator-associated pneumonia (VAP), including bacterial resistance, prescription errors, and de-escalation of antibiotic therapy.

Methods

This retrospective study included 120 cases of Ventilator-associated pneumonia admitted to the adult adult intensive care unit of the Federal University of Uberlândia. The chi-square test was used to compare qualitative variables. Student's t-test was used for quantitative variables and multiple logistic regression analysis to identify independent predictors of mortality.

Findings

De-escalation of antibiotic therapy and resistant bacteria did not influence mortality. Mortality was 4 times and 3 times higher, respectively, in patients who received an inappropriate antibiotic loading dose and in patients whose antibiotic dose was not adjusted for renal function. Multiple logistic regression analysis revealed the incorrect adjustment for renal function was the only independent factor associated with increased mortality.

Conclusion

Prescription errors influenced mortality of patients with Ventilator-associated pneumonia, underscoring the challenge of proper Ventilator-associated pneumonia treatment, which requires continuous reevaluation to ensure that clinical response to therapy meets expectations.

Telavancin hospital-acquired pneumonia trials: impact of Gram-negative infections and inadequate Gram-negative coverage on clinical efficacy and all-cause mortality

BACKGROUND

When hospital-acquired or ventilator-associated bacterial pneumonia (HABP/VABP) is caused by gram-positive and gram-negative pathogens or both (mixed infections), the adequacy of gram-negative coverage (GNC) can confound the assessment of a gram-positive agent under study. This analysis examines the influence of gram-negative infections and the adequacy of GNC on clinical efficacy and all-cause mortality in the telavancin HABP/VABP phase 3 ATTAIN trials (Assessment of Telavancin for Treatment of Hospital-Acquired Pneumonia).

METHODS

This post hoc analysis evaluated 3 patient groups from ATTAIN: (1) gram-positive-only infections, (2) gram-positive-only and mixed infections-adequate GNC, and (3) gram-negative-only infections and mixed infections with inadequate GNC. For each, clinical efficacy at test of cure and all-cause mortality at day 28 were compared for telavancin and vancomycin.

RESULTS/CONCLUSIONS

In the ATTAIN safety population there were 16 more deaths in the telavancin arms than in the vancomycin arms. Of these, 13 were in patients with gram-negative-only infections (n = 9) or with mixed infections and inadequate GNC (n = 4) and all had estimated baseline creatinine clearances of <30ml/min. Based on this analysis, clinical response and all-cause mortality could be confounded because there were more patients with gram-negative pathogens at baseline and more patients received inadequate treatment of these gram-negative infections in the telavancin groups.

Clinical predictors and microbiology of ventilator-associated pneumonia in the intensive care unit: a retrospective analysis in six Italian hospitals

The purpose of this study was to assess the main clinical predictors and microbiological features of ventilator-associated pneumonia (VAP) in the Intensive Care Unit (ICU) environment. This work is a retrospective analysis over one year from September 2010 to September 2011. Patients' risk factors, causes of admission, comorbidities and respiratory specimens collected in six Italian ICUs were reviewed. Incidence and case fatality rate of VAP were evaluated. After stratification for VAP development, univariate and multivariate analyses were performed to assess the impact of patients' conditions on the onset of this infection. A total of 1,647 ICU patients (pts) were considered. Overall, 115 patients (6.9 %) experienced at least one episode of VAP. The incidence rate for VAP was 5.82/1,000 pts-days, with a case fatality rate of 44.3 %. Multivariate analysis showed that admission for neurological disorders (aIRR 4.12, CI 1.24-13.68, p = 0.02) and emergency referral to ICU from other hospitals (aIRR 2.11, CI 1.03-4.31, p = 0.04) were associated with higher risk of VAP, whereas a tendency to a higher risk of infection was detected for admission due to respiratory disease, cardiac disease, trauma and for having obesity or renal failure. A total of 372 microbiological isolates from respiratory specimens were collected in VAP patients. The most common species were Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa, showing high resistance rates to carbapenems. Neurological disorders and emergency referral at the admission into the ICU are significantly associated with the onset of VAP. A high incidence of multi-drug resistant Gram- species was detected in the respiratory specimens.

Investigational drugs in phase I and phase II clincial trials for the treatment of hospital-acquired pneumonia

INTRODUCTION

Hospital acquired pneumonia (HAP) is one of the main infections acquired by patients during a stay in hospital. The main issue when dealing with patients with HAP and ventilator associated pneumonia (VAP) is the increasing role of multi-drug resistant organisms (MDROs).

AREAS COVERED

In this review the authors summarize the actual situation of MDROs as a cause of HAP and VAP. They also review the current treatment options stated in the most important international guidelines. Finally, they focus on the investigational drugs that have reached the phase III stage of development and the novel compounds that are being studied in phase I and II clinical trials.

EXPERT OPINION

Thanks to their excellent activity against MDROs, drugs in development for the treatment of HAP and VAP can significantly improve the therapeutic options available. In selected patients, the possibility to administer directed therapy with monoclonal antibodies to specific pathogens is an exciting strategy in the fight against widespread resistance.

Clinical metagenomics for the management of hospital- and healthcare-acquired pneumonia

The increasing burden of multidrug-resistant bacteria affects the management of several infections. In order to prescribe adequate antibiotics, clinicians facing severe infections such as hospital-acquired pneumonia (HAP) need to promptly identify the pathogens and know their antibiotic susceptibility profiles (AST), which with conventional microbiology currently requires 24 and 48 h, respectively. Clinical metagenomics, based on whole genome sequencing of clinical samples, could improve the diagnosis of HAP, however, many obstacles remain to be overcome, namely the turn-around time, the quantification of pathogens, the choice of antibiotic resistance determinants (ARDs), the inference of the AST from metagenomic data and the linkage between ARDs and their host. Here, we propose to tackle those issues in a bottom-up, clinically driven approach.

Pseudomonas aeruginosa nosocomial pneumonia: impact of pneumonia classification

OBJECTIVE

To describe and compare the mortality associated with nosocomial pneumonia due to Pseudomonas aeruginosa (Pa-NP) according to pneumonia classification (community-onset pneumonia [COP], hospital-acquired pneumonia [(HAP], and ventilator-associated pneumonia [VAP]).

DESIGN

We conducted a retrospective cohort study of adults with Pa-NP. We compared mortality for Pa-NP among patients with COP, HAP, and VAP and used logistic regression to identify risk factors for hospital mortality and inappropriate initial antibiotic therapy (IIAT).

SETTING

Twelve acute care hospitals in 5 countries (United States, 3; France, 2; Germany, 2; Italy, 2; and Spain, 3).

PATIENTS/PARTICIPANTS

A total of 742 patients with Pa-NP.

RESULTS

Hospital mortality was greater for those with VAP (41.9%) and HAP (40.1%) compared with COP (24.5%) (P<.001). In multivariate analyses, independent predictors of hospital mortality differed by pneumonia classification (COP: need for mechanical ventilation and intensive care; HAP: multidrug-resistant isolate; VAP: IIAT, increasing age, increasing Charlson comorbidity score, bacteremia, and use of vasopressors). Presence of multidrug resistance was identified as an independent predictor of IIAT for patients with COP and HAP, whereas recent antibiotic administration was protective in patients with VAP.

CONCLUSIONS

Among patients with Pa-NP, pneumonia classification identified patients with different risks for hospital mortality. Specific risk factors for hospital mortality also differed by pneumonia classification and multidrug resistance appeared to be an important risk factor for IIAT. These findings suggest that pneumonia classification for P. aeruginosa identifies patients with different mortality risks and specific risk factors for outcome and IIAT.

Prognostic factors associated with mortality of drug-resistant Acinetobacter baumannii ventilator-associated pneumonia

Background

Ventilator-associated pneumonia (VAP) caused by drug-resistant Acinetobacter baumannii is associated with high mortality in critically ill patients. We identified the prognostic factors of 30-day mortality in patients with VAP caused by drug-resistant A. baumannii and compared survival outcomes among multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR) A. baumannii VAP.

Methods

A retrospective cohort study was conducted in the Medical Intensive Care Unit at Chiang Mai University Hospital, Thailand. All adult patients diagnosed with A. baumannii VAP between 2005 and 2011 were eligible. Univariable and multivariable Cox’s proportional hazards regression were performed to identify the prognostic factors of 30-day mortality.

Results

A total of 337 patients with microbiologically confirmed A. baumannii VAP were included. The proportion of drug-sensitive (DS), MDR, XDR, and PDR A. baumannii were 9.8%, 21.4%, 65.3%, and 3.6%, respectively. The 30-day mortality rates were 21.2%, 31.9%, 56.8%, and 66.7%, respectively. The independent prognostic factors were SOFA score >5 (hazard ratio (HR) = 3.33, 95% confidence interval (CI) 1.94–5.72, P < 0.001), presence of septic shock (HR = 2.66, 95% CI 1.71–4.12, P < 0.001), Simplified Acute Physiology Score (SAPS) II >45 (HR = 1.58, 95% CI 1.01–2.46, P = 0.045), and inappropriate initial antibiotic treatment (HR = 1.53, 95% CI 1.08–2.20, P = 0.016).

Conclusions

Drug-resistant A. baumannii, particularly XDR and PDR, was associated with a high mortality rate. Septic shock, high SAPS II, high SOFA score, and inappropriate initial antibiotic treatment were independent prognostic factors for 30-day mortality.

Ventilator-associated pneumonia: present understanding and ongoing debates

INTRODUCTION

Ventilator-associated pneumonia (VAP) is a common cause of nosocomial infection, and is related to significant utilization of health-care resources. In the past decade, new data have emerged about VAP epidemiology, diagnosis, treatment and prevention.

RESULTS

Classifying VAP strictly based on time since hospitalization (early- and late-onset VAP) can potentially result in undertreatment of drug-resistant organisms in ICUs with a high rate of drug resistance, and overtreatment for patients not infected with resistant pathogens. A combined strategy incorporating diagnostic scoring systems, such as the Clinical Pulmonary Infection Score (CPIS), and either a quantitative or qualitative microbiological specimen, plus serial measurement of biomarkers, leads to responsible antimicrobial stewardship. The newly proposed ventilator-associated events (VAE) surveillance definition, endorsed by the Centers for Disease Control and Prevention, has low sensitivity and specificity for diagnosing VAP and the ability to prevent VAE is uncertain, making it a questionable surrogate for the quality of ICU care. The use of adjunctive aerosolized antibiotic treatment can provide high pulmonary concentrations of the drug and may facilitate shorter durations of therapy for multi-drug-resistant pathogens. A group of preventive strategies grouped as a 'ventilator bundle' can decrease VAP rates, but not to zero, and several recent studies show that there are potential barriers to implementation of these prevention strategies.

CONCLUSION

The morbidity and mortality related to VAP remain high and, in the absence of a gold standard test for diagnosis, suspected VAP patients should be started on antibiotics based on recommendations per the 2005 ATS guidelines and knowledge of local antibiotic susceptibility patterns. Using a combination of clinical severity scores, biomarkers, and cultures might help with reducing the duration of therapy and achieving antibiotic de-escalation.

Detection of pneumonia associated pathogens using a prototype multiplexed pneumonia test in hospitalized patients with severe pneumonia

Severe pneumonia remains an important cause of morbidity and mortality. Polymerase chain reaction (PCR) has been shown to be more sensitive than current standard microbiological methods – particularly in patients with prior antibiotic treatment – and therefore, may improve the accuracy of microbiological diagnosis for hospitalized patients with pneumonia. Conventional detection techniques and multiplex PCR for 14 typical bacterial pneumonia-associated pathogens were performed on respiratory samples collected from adult hospitalized patients enrolled in a prospective multi-center study. Patients were enrolled from March until September 2012. A total of 739 fresh, native samples were eligible for analysis, of which 75 were sputa, 421 aspirates, and 234 bronchial lavages. 276 pathogens were detected by microbiology for which a valid PCR result was generated (positive or negative detection result by Curetis prototype system). Among these, 120 were identified by the prototype assay, 50 pathogens were not detected. Overall performance of the prototype for pathogen identification was 70.6% sensitivity (95% confidence interval (CI) lower bound: 63.3%, upper bound: 76.9%) and 95.2% specificity (95% CI lower bound: 94.6%, upper bound: 95.7%). Based on the study results, device cut-off settings were adjusted for future series production. The overall performance with the settings of the CE series production devices was 78.7% sensitivity (95% CI lower bound: 72.1%) and 96.6% specificity (95% CI lower bound: 96.1%). Time to result was 5.2 hours (median) for the prototype test and 43.5 h for standard-of-care. The Pneumonia Application provides a rapid and moderately sensitive assay for the detection of pneumonia-causing pathogens with minimal hands-on time.

Trial Registration

Deutsches Register Klinischer Studien (DRKS) DRKS00005684

Role of Appropriate Therapy in Combating Mortality among the Ventilated Patients

CONTEXT

Ventilator associated pneumonia (VAP) is a nosocomial infection prevalent among the intensive care unit (ICU) patients despite proper infection control practices. The diagnosis of VAP still remains controversial and hence the mortality rate is higher among this group of patients.

AIM

The aim of our study was to identify the antibiotic pattern and the appropriateness of treatment followed in the ICU in relation with the clinical pulmonary infection score (CPIS) as a tool to diagnose VAP. This was compared with patients who had an inappropriate treatment in comparison to the CPIS and the clinical outcome.

RESULTS

Out of the 18 VAP patients, 12 (66.7%) received appropriate therapy based on the antibiotic susceptibility pattern of the causative organism, while 1 (5.5%) received partially inappropriate therapy and 5 (27.8%) received totally inappropriate therapy. Nine of the 18 (50%) VAP patients died, while only 5 of the 58 (8.6%) patients without VAP died. 72.2% patients with VAP received appropriate treatment based on the sensitivity of the isolates. The mortality rate in VAP patients receiving inappropriate therapy was 80%, while in those receiving appropriate therapy the mortality rate was 38.5%. The mortality rate among VAP patients with blood culture positivity was 100%, while it was 43.75% among those with negative blood culture.

CONCLUSION

The mortality rate among the patients receiving inappropriate therapy is high compared to other group of patients. Hence, a proper evaluation and administration of appropriate antibiotics can curb mortality among the ventilated patients.

A translational approach to ventilator associated pneumonia

The management of Ventilator Associated Pneumonia (VAP) presents many difficulties because of the heterogeneity of the disease; the way the immunocompromised host and the aggressive ICU environment interact is only partially discovered, the available biomarkers for diagnosis are not sufficient to ensure prompt differentiation between sick patients and patients at risk, the microbiological cultures require invasive techniques and time consuming methods. A translational medicine and bio-informatics approach can enable the identification of the main players of pathology, which may represent novel therapeutic targets or biomarker candidates. Analysis of proteome i.e. allows to individuate proteins that act as biomarkers, for patient-centered research strategies. Similarly, the genomic approach has proved useful to individuate those patients who are prone to develop VAP, and, in the future, we could be able to immunomodulate their responses to save them from nosocomial infections.

Weighted-incidence syndromic combination antibiograms to guide empiric treatment of critical care infections: a retrospective cohort study

Introduction

Empiric antimicrobial selection for critical care infections must balance the need for timely adequate coverage with the resistance pressure exerted by broadspectrum agents. We estimated the potential of weighted incidence syndromic combination antibiograms (WISCAs) to improve time to adequate coverage for critical care infections. In contrast to traditional antibiograms, WISCAs display the likelihood of coverage for a specific infectious syndrome (rather than individual pathogens), and also take into account the potential for poly-microbial infections and the use of multi-drug regimens.

Methods

Cases of ventilator-associated pneumonia (VAP) and catheter-related bloodstream infection (CRBSI) were identified over three years using stringent surveillance criteria. Based on the susceptibility profile of the culprit pathogens, we calculated the WISCA percentages of infections that would have been adequately covered by common antimicrobial(s). We then computed the excess percentage coverage offered by WISCA regimens compared to the actual antimicrobials administered to patients by 12 h, 24 h, and 48 h from culture collection.

Results

Among 163 patients with critical care infection, standard practice only resulted in adequate coverage of 35% of patients by 12 h, 52% by 24 h, and 75% by 48 h. No WISCA mono-therapy regimen offered greater than 85% adequate overall coverage for VAP and CRBSI. A wide range of dual therapy regimens would have conferred greater than 90% adequate coverage, with excess coverage estimated to be as high as +56%, +42% and +18% at 12 h, 24 h and 48 h, respectively. We did not detect a decrease in mortality associated with early adequate treatment, and so could not estimate potential downstream benefits.

Conclusions

WISCA-derived empiric antimicrobial regimens can be calculated for patients with intensive care unit (ICU)-acquired infections, and have the potential to reduce time to adequate treatment. Prospective research must confirm whether implementation of WISCA prescribing aids facilitate timely adequate treatment and improved ICU outcomes.

A rapid, real-time quantitative polymerase chain reaction test for the identification of pathogens in bronchoalveolar lavage samples

BACKGROUND

Standard bacteriologic culture techniques offer results within 2 days to 3 days, precluding a focused and timely antibiotic therapy in ventilated trauma patients. Our laboratory developed a real-time quantitative polymerase chain reaction (qPCR) test that can detect 25 different bacteria and fungi and methicillin resistance and offers results within 3 hours. The objective of this study was to compare the qPCR method to standard culture techniques.

METHODS

This was a prospective observational cohort study at a Level I trauma center from 2009 to 2012. Adult trauma patients on ventilation, receiving at least one bronchoalveolar lavage (BAL) with culture results were eligible for inclusion. DNA was isolated from the BAL samples and analyzed in 96-well plates using qPCR. Student's t tests were used to examine differences in mean qPCR cycle counts. Sensitivities, specificities, negative predictive values, and positive predictive values were calculated for the qPCR primer sets.

RESULTS

There were 28 BALs in the study. The qPCR method detected a total of 165 organisms, and culture methods found 54. The qPCR test had an overall sensitivity of 85%, specificity of 74%, negative predictive value of 98%, and positive predictive value of 27%. Those organisms that were only identified through qPCR had significantly less DNA than those identified through both qPCR and quantitative culture (28.8 vs. 23.3, p < 0.001). Concurrent antibiotic therapy was found to decrease the qPCR specificity in some primer sets, and methicillin resistance was only found in BAL samples that were concurrent with antibiotics.

CONCLUSION

The qPCR method shows promising initial diagnostic value. Many of the organisms not identified by quantitative culture had late cycle calls, suggesting that they might have been in quantities too low to result in culture identification. Once refined, our qPCR method has the potential to identify pathogens faster and earlier than standard quantitative culture methods, allowing for targeted antibiotic therapy within 3 hours.

LEVEL OF EVIDENCE

Diagnostic test, level II.

How to approach and treat VAP in ICU patients

Background

Ventilator-associated pneumonia (VAP) is one of the most frequent clinical problems in ICU with an elevated morbidity and costs associated with it, in addition to prolonged MV, ICU-length of stay (LOS) and hospital-length of stay. Current challenges in VAP management include the absence of a diagnostic gold standard; the lack of evidence regarding contamination vs. airway colonization vs. infection; and the increasing antibiotic resistance. We performed a Pubmed search of articles addressing the management of ventilator-associated pneumonia (VAP). Immunocompromised patients, children and VAP due to multi-drug resistant pathogens were excluded from the analysis. When facing a patient with VAP, it’s important to address a few key questions for the patient’s optimal management: when should antibiotics be started?; what microorganisms should be covered?; is there risk for multirresistant microorganisms?; how to choose the initial agent?; how microbiological tests determine antibiotic changes?; and lastly, which dose and for how long?. It’s important not to delay adequate treatment, since outcomes improve when empirical treatment is early and effective. We recommend short course of broad-spectrum antibiotics, followed by de-escalation when susceptibilities are available. Individualization of treatment is the key to optimal management.

Interaction of drug- and granulocyte-mediated killing of Pseudomonas aeruginosa in a murine pneumonia model

BACKGROUND

Killing of bacterial pathogens by granulocytes is a saturable process, as previously demonstrated. There is virtually no quantitative information about how granulocytes interact with antimicrobial chemotherapy to kill bacterial cells.

METHODS

We performed a dose-ranging study with the aminoglycoside plazomicin against Pseudomonas aeruginosa ATCC27853 in a granulocyte-replete murine pneumonia model. Plazomicin was administered in a humanized fashion (ie, administration of decrementing doses 5 times over 24 hours, mimicking a human daily administration profile). Pharmacokinetic profiling was performed in plasma and epithelial lining fluid. All samples were simultaneously analyzed with a population model. Mouse cohorts were treated for 24 hours; other cohorts treated with the same therapy were observed for another 24 hours after therapy cessation, allowing delineation of the therapeutic effect necessary to reduce the bacterial burden to a level below the half-saturation point.

RESULTS

The mean bacterial burden (±SD) at which granulocyte-mediated kill was half saturable was 2.45 × 10(6) ± 6.84 × 10(5) colony-forming units of bacteria per gram of tissue (CFU/g). Higher levels of plazomicin exposure reduced the bacterial burden to <5 log10 CFU/g, allowing granulocytes to kill an additional 1.0-1.5 log CFU/g over the subsequent 24 hours.

CONCLUSIONS

For patients with large bacterial burdens (eg, individuals with ventilator-requiring hospital-acquired pneumonia), it is imperative to kill ≥2 log10 CFU/g early after treatment initiation, to allow the granulocytes to contribute optimally to bacterial clearance.

A simple mathematical model to determine the ideal empirical antibiotic therapy for bacteremic patients

Background

Local epidemiological data are always helpful when choosing the best antibiotic regimen, but it is more complex than it seems as it may require the analysis of multiple combinations. The aim of this study was to demonstrate a simplified mathematical calculation to determine the most appropriate antibiotic combination in a scenario where monotherapy is doomed to failure.

Methods

The susceptibility pattern of 11 antibiotics from 216 positive blood cultures from January 2012 to January 2013 was analyzed based on local policy. The length of hospitalization before bacteremia and the unit (ward or intensive care unit) were the analyzed variables. Bacteremia was classified as early, intermediate or late. The antibiotics were combined according to the combination model presented herein.

Results

A total of 55 possible mathematical associations were found combining 2 by 2, 165 associations with 3 by 3 and 330 combinations with 4 by 4. In the intensive care unit, monotherapy never reached 80% of susceptibility. In the ward, only carbapenems covered more than 90% of early bacteremia. Only three drugs combined reached a susceptibility rate higher than 90% anywhere in the hospital. Several regimens using four drugs combined reached 100% of susceptibility.

Conclusions

Association of three drugs is necessary for adequate coverage of empirical treatment of bacteremia in both the intensive care unit and the ward.

Update on management options in the treatment of nosocomial and ventilator assisted pneumonia: review of actual guidelines and economic aspects of therapy

Objective

Nosocomial or more exactly, hospital-acquired (HAP) and ventilator-associated pneumonia (VAP) are frequent conditions when treating intensive care unit (ICU) patients that are only exceeded by central line-associated bloodstream infections. In Germany, approximately 18,900 patients per year suffer from a VAP and another 4,200 from HAP. We therefore reviewed the current guidelines about HAP and VAP, from different sources, regarding the strategies to address individual patient risks and medication strategies for initial intravenous antibiotic treatment (IIAT).

Material and methods

We conducted an analysis of the recent guidelines for the treatment of HAP. The current guidelines of the American Thoracic Society, the treatment recommendations of the Paul-Ehrlich-Gesellschaft (PEG), the guidelines from the British Society for Antimicrobial Chemotherapy, the VAP guideline of the Canadian Critical Care trials group, as well as the new German S3-guideline for HAP were examined.

Results

All guidelines are based on grading systems that assess the evidence underlying the recommendations. However, each guideline uses different grading systems. One common aspect of these guidelines is the risk assessment of the patients for decision making regarding IIAT. Most guidelines have different recommendations depending on the risk of the presence of multidrug resistant (MDR) bacteria. In guidelines using risk assessment, for low-risk patients (early onset, no MDR risk) aminopenicillins with beta-lactamase inhibitors (BLI), second or third generation cephalosporins, quinolones, or ertapenem are recommended. For patients with higher risk, imipenem, meropenem, fourth generation cephalosporins, ceftazidime or piperacillin/tazobactam are recommended. The PEG recommendations include a combination therapy in cases of very high risk (late onset, MDR risk, ICU, and organ failure) of either piperacillin/tazobactam, dori-, imi- or meropenem or cefepime or ceftazidime with ciprofloxacin, levofloxacin, fosfomycin or an aminoglycoside. For the treatment of HAP caused by methicillin-resistant Staphylococcus aureus (MRSA), either linezolid or vancomycin is recommended. With regard to the ZEPHyR-trial, linezolid has shown higher cure rates but, no difference in overall survival. Economic analyses show the relevance of guideline-adherent IIAT (GA-IIAT). Besides significantly better clinical outcomes, patients with GA-IIAT cause significantly lower costs (€28,033 versus (vs) €36,139) (P=0.006) and have a shorter length of stay in hospital (23.9 vs 28.3 days) (P=0.022).

Conclusion

We conclude that most current treatment guidelines take into account the individual patient risk and that the correct choice of IIAT affects clinical as well as economical outcomes.

How should we dose antibiotics for pneumonia in the ICU?

PURPOSE OF REVIEW

Pneumonia continues to be a common reason for, or complication of, ICU admission. Associated morbidity and mortality remain high, with an increasing incidence of multidrug-resistant organisms. Appropriate antibiotic therapy, both in terms of spectrum of cover and dose, remains the cornerstone of effective management.

RECENT FINDINGS

Critically ill patients will frequently manifest significantly altered end-organ function, as compared with an ambulatory or ward-based setting. Such changes can have profound effects on antibiotic drug handling, promoting subtherapeutic concentrations, treatment failure or the selection of resistant organisms. Standard antibiotic regimens typically fail to consider such issues, with recent literature highlighting the need for improved dosing to achieve sufficient intrapulmonary concentrations, particularly in the setting of augmented elimination. Although recent clinical trials utilizing strategies that optimize drug exposure (either through the use of agents with improved penetration, or continuous infusions) demonstrate superior surrogate outcomes, a mortality benefit is still uncertain.

SUMMARY

Antibiotic dosing strategies that are adapted to a critical care environment are urgently needed, both to improve clinical outcomes and ensure therapeutic longevity. Similarly, study protocols investigating emerging antibiotics must also be designed accordingly, to prevent potential setbacks in drug availability.

Empirical Antibiotic Therapy for Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is the most common infectious complication in the intensive care unit. It can increase duration of mechanical ventilation, length of stay, costs, and mortality. Improvements in the administration of empirical antibiotic therapy have potential to reduce the complications of VAP. This review will discuss the current data addressing empirical antibiotic therapy and the effect on mortality in patients with VAP. It will also address factors that could improve the administration of empirical antibiotics and directions for future research.