APPROPRIATE AND TIMELY EMPIRICAL ANTIMICROBIAL TREATMENT OF ICU INFECTIONS - A ROLE FOR CARBAPENEMS

Detection of Extended-Spectrum β-Lactamase and Carbapenemase Activity in Gram-Negative Bacilli Using Liquid Chromatography - Tandem Mass Spectrometry

Purpose

Several mass spectrometry-based methods for antimicrobial sensitivity testing have been described in recent years. They offer an alternative to commercially available testing systems which were considered to have disadvantages in terms of cost- and time-efficiency. The aim of this study was to develop an LC-MS/MS-based antibiotic hydrolysis assay for evaluating antimicrobial resistance (AMR) of Gram-negative bacteria.

Materials and Methods

Four species of Gram-negative bacilli (Klebsiella pneumoniae, Escherichia coli, Providencia stuartii and Acinetobacter baumannii) were tested against six antibiotics from three different classes: ampicillin, meropenem, imipenem, ceftazidime, ceftriaxone and cefepime. Bacterial suspensions from each species were incubated with a mixture of the six antibiotics. Any remaining antibiotic following incubation was measured using LC-MS/MS. The results were interpreted using measurements obtained for an E. coli strain sensitive to all antibiotics and expressed as percentage of hydrolyzed antibiotic. These were subsequently compared to commercially-available system for the bacteria identification and susceptibility testing.

Results

Overall, LC-MS/MS assay and commercial antimicrobial susceptibility platform results showed good agreement in terms of an organism being resistant/sensitive to an antibiotic. The time required to complete the LC-MS/MS-based hydrolysis test was under 5 h, significantly shorter that commercially available susceptibility testing platforms.

Conclusion

By using a sensitive strain for results interpretation and simultaneous use of multiple antibiotics, the proposed protocol offers improved robustness and multiplexing over previously described methods for antibiotic sensitivity testing. Nevertheless, further research is needed before routine assimilation of the method, especially for strains with intermediate resistance.

Multidrug-Resistant Gram-Negative Bacilli: A Retrospective Study of Trends in a Tertiary Healthcare Unit

Background and objective: Bacterial multidrug resistance is particularly common in Gram-negative bacilli (GNB), with important clinical consequences regarding their spread and treatment options. The aim of this study was to investigate the trend of multidrug-resistant GNB (MDR-GNB) in high-risk hospital departments, between 2000–2015, in intervals of five years, with the intention of improving antibiotic therapy policies and optimising preventive and control practices. Materials and methods: This is an observational, retrospective study performed in three departments of the most important tertiary healthcare unit in the southwestern part of Romania: the Intensive Care Unit (ICU), the General Surgery Department (GSD), and the Nutrition and Metabolic Diseases Department (NMDD). MDR was defined as acquired resistance to at least one agent in three or more antimicrobial categories. Trends over time were determined by the Cochran–Armitage trend test and linear regression. Results: During the study period, a total of 2531 strains of MDR-GNB were isolated in 1999 patients: 9.20% in 2000, 18.61% in 2005, 37.02% in 2010, and 35.17% in 2015. The most significant increasing trend was recorded in the ICU (gradient = 7.63, R² = 0.842, p < 0.001). The most common MDR-GNB in the ICU was isolated from bronchoalveolar aspiration samples. Concerning the proportion of different species, most of the changes were recorded in the ICU, where a statistically significant increasing trend was observed for Proteus mirabilis (gradient = 2.62, R² = 0.558, p < 0.001) and Acinetobacter baumannii (gradient = 2.25, R² = 0.491, p < 0.001). Analysis of the incidence of the main resistance phenotypes proportion identified a statistically significant increase in carbapenem resistance in the ICU (Gradient = 8.27, R² = 0.866, p < 0.001), and an increased proportion of aminoglycoside-resistant strains in all three departments, but more importantly in the ICU and GSD. Conclusion: A statistically significant increasing trend was observed in all three departments; the most significant one was recorded in the ICU, where after 2010, carbapenem-resistant strains were isolated.

De-escalation of antimicrobial treatment for adults with sepsis, severe sepsis or septic shock

BACKGROUND

Mortality rates among patients with sepsis, severe sepsis or septic shock are highly variable throughout different regions or services and can be upwards of 50%. Empirical broad-spectrum antimicrobial treatment is aimed at achieving adequate antimicrobial therapy, thus reducing mortality; however, there is a risk that empirical broad-spectrum antimicrobial treatment can expose patients to overuse of antimicrobials. De-escalation has been proposed as a strategy to replace empirical broad-spectrum antimicrobial treatment by using a narrower antimicrobial therapy. This is done by reviewing the patient's microbial culture results and then making changes to the pharmacological agent or discontinuing a pharmacological combination.

OBJECTIVES

To evaluate the effectiveness and safety of de-escalation antimicrobial treatment for adult patients diagnosed with sepsis, severe sepsis or septic shock caused by any micro-organism.

SEARCH METHODS

In this updated version, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 10); MEDLINE via PubMed (from inception to October 2012); EMBASE (from inception to October 2012); LILACS (from inception to October 2012); Current Controlled Trials; bibliographic references of relevant studies; and specialists in the area. We applied no language restriction. We had previously searched the databases to August 2010.

SELECTION CRITERIA

We planned to include randomized controlled trials (RCTs) comparing de-escalation (based on culture results) versus standard therapy for adults with sepsis, severe sepsis or septic shock. The primary outcome was mortality (at 28 days, hospital discharge or at the end of the follow-up period). Studies including patients initially treated with an empirical but not adequate antimicrobial therapy were not considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors planned to independently select and extract data and to evaluate methodological quality of all studies. We planned to use relative risk (risk ratio) for dichotomous data and mean difference (MD) for continuous data, with 95% confidence intervals. We planned to use the random-effects statistical model when the estimate effects of two or more studies could be combined in a meta-analysis.

MAIN RESULTS

Our search strategy retrieved 493 studies. No published RCTs testing de-escalation of antimicrobial treatment for adult patients diagnosed with sepsis, severe sepsis or septic were included in this review. We found one ongoing RCT.

AUTHORS' CONCLUSIONS

There is no adequate, direct evidence as to whether de-escalation of antimicrobial agents is effective and safe for adults with sepsis, severe sepsis or septic shock. This uncertainty warrants further research via RCTs and the authors are awaiting the results of an ongoing RCT testing the de-escalation of empirical antimicrobial therapy for severe sepsis.

An antimicrobial stewardship program improves antimicrobial treatment by culture site and the quality of antimicrobial prescribing in critically ill patients

Introduction

Increasing antimicrobial costs, reduced development of novel antimicrobials, and growing antimicrobial resistance necessitate judicious use of available agents. Antimicrobial stewardship programs (ASPs) may improve antimicrobial use in intensive care units (ICUs). Our objective was to determine whether the introduction of an ASP in an ICU altered the decision to treat cultures from sterile sites compared with nonsterile sites (which may represent colonization or contamination). We also sought to determine whether ASP education improved documentation of antimicrobial use, including an explicit statement of antimicrobial regimen, indication, duration, and de-escalation.

Methods

We retrospectively analyzed consecutive patients with positive bacterial cultures admitted to a 16-bed medical-surgical ICU over 2-month periods before and after ASP introduction (April through May 2008 and 2009, respectively). We evaluated the antimicrobial treatment of positive sterile- versus nonsterile-site cultures, specified a priori. We reviewed patient charts for clinician documentation of three specific details regarding antimicrobials: an explicit statement of antimicrobial regimen/indication, duration, and de-escalation. We also analyzed cost and defined daily doses (DDDs) (a World Health Organization (WHO) standardized metric of use) before and after ASP.

Results

Patient demographic data between the pre-ASP (n = 139) and post-ASP (n = 130) periods were similar. No difference was found in the percentage of positive cultures from sterile sites between the pre-ASP period and post-ASP period (44.9% versus 40.2%; P = 0.401). A significant increase was noted in the treatment of sterile-site cultures after ASP (64% versus 83%; P = 0.01) and a reduction in the treatment of nonsterile-site cultures (71% versus 46%; P = 0.0002). These differences were statistically significant when treatment decisions were analyzed both at an individual patient level and at an individual culture level. Increased explicit antimicrobial regimen documentation was observed after ASP (26% versus 71%; P < 0.0001). Also observed were increases in formally documented stop dates (53% versus 71%; P < 0.0001), regimen de-escalation (15% versus 23%; P = 0.026), and an overall reduction in cost and mean DDDs after ASP implementation.

Conclusions

Introduction of an ASP in the ICU was associated with improved microbiologically targeted therapy based on sterile or nonsterile cultures and improved documentation of antimicrobial use in the medical record.

PCT as a diagnostic and prognostic tool in burn patients. Whether time course has a role in monitoring sepsis treatment

OBJECTIVE

To evaluate the diagnostic and prognostic performance of inflammatory markers for septic and non septic (localized) bacterial infections in patients with severe burn.

METHODS AND RESULTS

Data of 145 patients were prospectively included in this study. Serum procalcitonin and other inflammatory markers were measured within 24 h after burn and daily thereafter. Maximum procalcitonin (p=0.004) was independent predictors of outcome in logistic regression analysis. PCT thresholds of 1.5 ng/ml, 0.52 ng/ml and 0.56 ng/ml had adequate sensitivity and specificity to diagnose sepsis, respiratory tract and wound infections respectively. A threshold value of 7.8 ng/ml in PCT concentration on day 3 was associated with the effectiveness of the sepsis treatment with an AUC of 0.86 (95% CI 0.69-1.03, p=0.002). C-reactive protein levels and WBCs showed no significant change over the first 3 days in the patients with successfully treated sepsis (p=0.93).

CONCLUSION

The maximum procalcitonin level has prognostic value in burn patients. PCT can be used as a diagnostic tool in patients with infectious complications with or without bacteremia during ICU stay. Daily consecutive PCT measurements may be a valuable tool in monitoring the effectiveness of antibiotic therapy in burn ICU patients.

The use of carbapenems in the treatment of serious infections

Inadequate initial antimicrobial treatment in serious infections leads to increased mortality. Achieving adequate treatment is increasingly difficult because of the increasing prevalence of multidrug-resistant (MDR) pathogens. The carbapenems are potent, broad-spectrum antibiotics that have been shown to be safe and efficacious therapies in the treatment of serious infections. This review is intended to compare the 4 major members of the carbapenem class, which include imipenem, meropenem, ertapenem, and doripenem, with other widely used antimicrobial agents in the intensive care unit (ICU). The carbapenems are potent, broad-spectrum antibiotics that have been shown to be safe and efficacious therapies in the treatment of serious infections. They provide better gram-negative coverage than other beta-lactams and are stable against extended-spectrum beta-lactamases and AmpC beta-lactamases, making them effective in the treatment of many MDR bacteria. The newly approved carbapenem, doripenem, may help preserve the utility of the carbapenem class.

Clinical microbiology of early-onset and late-onset neonatal sepsis, particularly among preterm babies

Prematurity has got special challenge for clinicians and also other medical staff, such as microbiologists. Immature host defense mechanisms support early-onset sepsis, which can be very serious with very high mortality. While the past decade has been marked by a significant decline in early-onset group B streptococcal (GBS) sepsis in both term and preterm neonates, the overall incidence of early-onset sepsis has not decreased in many centers, and several studies have found an increase in sepsis due to gram-negative organisms. With increasing survival of these more fastidious preterm infants, late-onset sepsis or specially nosocomial bloodstream infection (BSI) will continue to be a challenging complication that affects other morbidities, length of hospitalization, cost of care, and mortality rates. Especially the very low birthweight (VLBW) infants sensitive to serious systemic infection during their initial hospital stay. Sepsis caused by multiresistant organisms and Candida spp. are also increasing in incidence, has become the most common cause of death among preterm infants. This review focuses on the clinical microbiology of neonatal sepsis, particularly among preterm babies, summarizing the most frequent bacterial and fungal organisms causing perinatally acquired and also nosocomial sepsis.

Update on the management of infection in patients with severe sepsis

Morbidity and mortality associated with the development of severe sepsis remain unacceptably high. However, with the introduction of a protocol called early goal-directed therapy, significant benefits in terms of patient's outcome have been demonstrated. In an aim to improve outcome and to increase awareness, practical evidence-based guidelines for the management of severe sepsis and septic shock were developed under the auspices of the Sepsis Surviving Campaign, easy to apply by the bedside medical and nursing staff. The treatment of severe sepsis includes 3 main essentials: (1) eradication of the inciting infection using source control measures and empiric antimicrobials, (2) hemodynamic resuscitation of tissue hypoperfusion using fluids and inotropic drugs to prevent life-threatening organ damage, and (3) sustained organ support using mechanical interventions to diminish organ injury. This review article highlights the anti-infective approach of the management of sepsis.

New developments in carbapenems

Antibiotic resistance among Gram-negative pathogens in hospitals is a growing threat to patients and is driving the increased use of carbapenems. Carbapenems are potent members of the beta-lactam family of antibiotics, with a history of safety and efficacy for serious infections that exceeds 20 years. Original and review articles were identified from a Medline search (1979-2008). Reference citations from identified publications, abstracts from the Interscience Conferences on Antimicrobial Agents and Chemotherapy and package inserts were also used. Carbapenems are effective in treating severe infections at diverse sites, with relatively low resistance rates and a favourable safety profile. Carbapenems are the beta-lactams of choice for the treatment of infections caused by multidrug-resistant organisms. Optimized dosing of carbapenems should limit the emergence of resistance and prolong the utility of these agents. The newly approved doripenem should prove to be a valuable addition to the currently available carbapenems: imipenem, meropenem and ertapenem.

Clinical and pulmonary thin-section CT findings in acute Klebsiella pneumoniae pneumonia

The aim of this study was to assess the clinical and pulmonary thin-section CT findings in patients with acute Klebsiella pneumoniae pneumonia. We retrospectively evaluated thin-section CT examinations performed between January 1991 and December 2007 from 962 patients with acute Klebsiella pneumoniae pneumonia. Seven hundred and sixty-four cases with concurrent infectious diseases were excluded. Thus, our study group comprised 198 patients (118 male, 80 female; age range 18-97 years, mean age 61.5). Underlying diseases and clinical findings were assessed. Parenchymal abnormalities were evaluated along with the presence of enlarged lymph nodes and pleural effusion. CT findings in patients with acute Klebsiella pneumoniae pneumonia consisted mainly of ground-glass attenuation (100%), consolidation (91.4%), and intralobular reticular opacity (85.9%), which were found in the periphery (96%) of both sides of the lungs (72.2%) and were often associated with pleural effusion (53%). The underlying conditions in patients with Klebsiella pneumoniae pneumonia were alcoholism or smoking habit.

Blood stream infections of abdominal origin in the intensive care unit: characteristics and determinants of death

BACKGROUND

Blood stream infections (BSI) of abdominal origin are associated with a high mortality rate. We hypothesized that both patient and microbiological factors determine death in critically ill patients who develop such infections.

METHODS

Ninety-six consecutive patients who developed BSI of abdominal origin in an 11-year period (1992-2002) in the intensive care unit (ICU) of the Ghent University Hospital were studied. Patient data were retrieved from a prospective registry of BSI. Demographics, disease severity, source of the BSI, incidence of organ failure, and outcome were recorded. Microbiological data were retrieved from the patient file and the hospital laboratory.

RESULTS

Secondary peritonitis and intra-abdominal abscesses were the source of the BSI in the majority of patients. The majority of the organisms involved were gram-negative, with Escherichia coli isolated most frequently. Twenty-one patients (22%) had polymicrobial BSI, and in 39 patients, at least one of the micro-organisms was antibiotic resistant (41%). The mortality rate in the whole patient group was 62.5% (60/96), which was significantly higher than the Acute Physiology and Chronic Health Evaluation (APACHE) II-based expected mortality rate (p < 0.001). Patients who died were older, had a tendency to have a higher APACHE II score on admission, and were more likely to suffer from acute renal failure and cardiovascular failure during their ICU stay. Logistic regression analysis revealed that the following factors were independently associated with death: Age (odds ratio [OR] 1.09; 95% confidence interval [CI] 1.04, 1.14; p < 0.001) (per year increase) and the occurrence of acute renal failure (OR 4.18; 95% CI 1.22, 14.31; p = 0.023).

CONCLUSIONS

The mortality rate of ICU patients who develop BSI of intra-abdominal origin is high. Gram-negative micro-organisms were isolated most frequently, and 41% of all organisms were antibiotic-resistant. Two patient-related factors (greater age and the development of acute renal failure) were associated independently with a higher mortality rate.

Carbapenems: a potent class of antibiotics

The purpose of this review is to assess the relative strengths and weaknesses of individual members of the carbapenem class of antibiotics. Clinical trials and review articles were identified from a Medline search (1979 - July 2006), in addition to, reference citations from identified publications, abstracts from the Interscience Conferences on Antimicrobial Agents and Chemotherapy and the 12th International Congress on Infectious Disease, and package inserts. Articles in English were reviewed, with emphasis on those containing efficacy or safety data. Carbapenems bind to critical penicillin-binding proteins, disrupting the growth and structural integrity of bacterial cell walls. They provide enhanced anaerobic and Gram-negative coverage as compared with other beta-lactams and their stability against extended-spectrum beta-lactamases (ESBLs) makes them an effective treatment option. The most common adverse effects are infusion-site complications and gastrointestinal distress. Ertapenem has limited efficacy against non-fermenting, Gram-negative bacteria, restricting its use to community-acquired infections. Imipenem is slightly more effective against Gram-positive organisms and meropenem slightly more effective against Gram-negative organisms. However, both have broad-spectrum activity, including non-fermenting, Gram-negative bacteria. Among non-fermenting, Gram-negatives, resistance to imipenem in particular is increasing. Doripenem is in late-stage clinical development and combines the broad-spectrum coverage of imipenem and meropenem, and more potent activity against Pseudomonas aeruginosa. Due to the increasing challenges represented by ESBLs and multi-drug resistant organisms, the carbapenems are assuming a greater role in the treatment of serious infections. Imipenem and meropenem are presently available and have been shown to be effective against nosocomial infections. Doripenem is an investigational carbapenem that has completed Phase III clinical trials and that has the potential to improve on this efficacy and minimize the emergence of resistance to the carbapenem class.

Costs and length of stay associated with antimicrobial resistance in acute kidney injury patients with bloodstream infection

INTRODUCTION

Antimicrobial resistance negatively impacts on prognosis. Intensive care unit (ICU) patients, and particularly those with acute kidney injury (AKI), are at high risk for developing nosocomial bloodstream infections (BSI) due to multi-drug-resistant strains. Economic implications in terms of costs and length of stay (LOS) attributable to antimicrobial resistance are underevaluated. This study aimed to assess whether microbial susceptibility patterns affect costs and LOS in a well-defined cohort of ICU patients with AKI undergoing renal replacement therapy (RRT) who developed nosocomial BSI.

METHODS

Historical study (1995-2004) enrolling all adult RRT-dependent ICU patients with AKI and nosocomial BSI. Costs were considered as invoiced in the Belgian reimbursement system, and LOS was used as a surrogate marker for hospital resource allocation.

RESULTS

Of the 1330 patients with AKI undergoing RRT, 92 had microbiologic evidence of nosocomial BSI (57/92, 62% due to a multi-drug-resistant microorganism). Main patient characteristics were equal in both groups. As compared to patients with antimicro-4 bial-susceptible BSI, patients with antimicrobial-resistant BSI were more likely to acquire Gram-positive infection (72.6% vs 25.5%, P<0.001). No differences were found neither in LOS (ICU before BSI, ICU, hospital before BSI, hospital, hospital after BSI, and time on RRT; all P>0.05) or hospital costs (all P>0.05) when comparing patients with antimicrobial-resistant vs antimicrobial-susceptible BSI. However, although not statistically significant, patients with BSI caused by resistant Gram-negative-, Candida-, or anaerobic bacteria incurred substantial higher costs than those without.

CONCLUSION

In a cohort of ICU patients with AKI and nosocomial BSI undergoing RRT, patients with antimicrobial-resistant vs antimicrobial-susceptible Gram-positive BSI did not have longer hospital stays, or higher hospital costs. Patients with resistant "other" (i.e. Gram-negative, Candida, or anaerobic) BSI were found to have a distinct trend towards increased resources use as compared to patients with susceptible "other" BSI, respectively.

Effects of delayed oxygenation assessment on time to antibiotic delivery and mortality in patients with severe community-acquired pneumonia*

BACKGROUND

Practice guidelines suggest processes of care such as timely oxygenation assessment and antibiotic therapy as quality indicators for the management of community-acquired pneumonia. The objective of this study was to determine whether postponed oxygenation assessment (either by pulse oximetry monitoring or arterial blood gas analysis) delays initiation of antibiotic therapy and adversely affects intensive care unit survival in patients with severe community-acquired pneumonia.

METHODS

Secondary analysis from a prospective, observational, multicenter study including 529 patients with community-acquired pneumonia admitted to the intensive care unit in 33 hospitals. Delays in processes of care describe the interval between time of triage at hospital admission and either time to oxygenation assessment or start of antibiotic therapy.

RESULTS

Postponing oxygenation assessment for >1 hr was associated with a significantly longer time to initiation of antibiotic therapy (median, 6 hrs [interquartile range, 3-9 hrs] vs. 3 hrs [2-5 hrs]; p < .001). Unadjusted linear regression analysis confirmed that a delay in oxygenation assessment of >1 hr was associated with an increase in time to first antibiotic dose of 6.13 hrs (95% confidence interval, 3.42-8.83; p < .001). In addition, a delay in oxygenation assessment of >3 hrs was associated with an increased risk of death (relative risk, 2.24; 95% confidence interval, 1.17-4.30). Multivariable analysis, adjusting for potential confounders, revealed that delayed oxygenation assessment (>3 hrs) was an independent risk factor of death (hazard ratio, 2.06; 95% confidence interval, 1.22-3.50).

CONCLUSIONS

In this population of patients with severe community-acquired pneumonia, early oxygenation assessment was associated with more rapid antibiotic delivery and better intensive care unit survival. These data suggest the potential value of an early care bundle focusing on implementation of oxygenation assessment immediately after arrival to the emergency department.

Bacteremia in patients with ventilator-associated pneumonia is associated with increased mortality: A study comparing bacteremic vs. nonbacteremic ventilator-associated pneumonia

OBJECTIVE

To assess whether bacteremic ventilator-associated pneumonia (B-VAP) differs in terms of risk factors, organisms, and outcomes from nonbacteremic VAP (NB-VAP).

DESIGN

A retrospective, single-center, observational, cohort study.

SETTING

Multidisciplinary teaching intensive care unit.

PATIENTS

Adult patients requiring mechanical ventilation, identified as having VAP in a 44-month prospective surveillance database.

INTERVENTIONS

Each B-VAP patient was matched with two controls with VAP and negative blood cultures based on the microbial etiology responsible for VAP, Acute Physiology and Chronic Health Evaluation II score on admission (+/-3 points), diagnostic category, and length of stay before pneumonia onset.

MEASUREMENTS AND MAIN RESULTS

B-VAP was documented in 35 (17.6%) of 199 microbiologically confirmed VAP episodes. B-VAP developed later (median 8 vs. 5 days, p = .03) and was more frequent in previously hospitalized patients (34.3% vs. 11.0%, p < .01) and in older patients (57.4 +/- 15.2 vs. 49.5 +/- 19.3 yrs, p = .02). B-VAP was more often caused by methicillin-resistant Staphylococcus aureus (12 [20.7%] vs. 13 [5.1%] episodes, p < .01), whereas Haemophilus influenzae was associated with NB-VAP (52 [20.4%] vs. 0, p < .01). Multivariate analysis confirmed an association between B-VAP and both methicillin-resistant S. aureus (odds ratio 3.18; 95% confidence interval 1.15-8.76, p < .01) and prior hospitalization (odds ratio 2.56; 95% confidence interval 1.01-6.54, p = .05). After adjustment for potential confounders, B-VAP (hazard ratio for death 2.55; 95% confidence interval 1.25-5.23, p = .01) and vasopressor use (hazard ratio 2.43; 95% confidence interval 1.23-4.82, p = .01) remained associated with mortality. The estimated relative risk of death for bacteremic cases was 2.86 (95% confidence interval 1.09-7.51), since mortality for cases and matched NB-VAP controls was 40.6% (13 of 32) and 19.3% (11 of 57), respectively.

CONCLUSIONS

B-VAP occurs later during intensive care unit stay, is more frequent in previously hospitalized patients, is more often caused by methicillin-resistant S. aureus, and is independently associated with increased intensive care unit mortality.

Dynamics of C-reactive protein and white blood cell count in critically ill patients with nosocomial Gram positive vs. Gram negative bacteremia: a historical cohort study

Background

Nosocomial bacteremia is associated with a poor prognosis. Early adequate therapy has been shown to improve outcome. Consequently, rapid detection of a beginning sepsis is therefore of the utmost importance. This historical cohort study was designed to evaluate if different patterns can be observed in either C-reactive protein (CRP) and white blood cell count (WCC) between Gram positive bacteremia (GPB) vs. Gram negative bacteremia (GNB), and to assess the potential benefit of serial measurements of both biomarkers in terms of early antimicrobial therapy initiation.

Methods

A historical study (2003–2004) was conducted, including all adult intensive care unit patients with a nosocomial bacteremia. CRP and WCC count measurements were recorded daily from two days prior (d_-2) until one day after onset of bacteremia (d₊₁). Delta (Δ) CRP and Δ WCC levels from the level at d_-2 onward were calculated.

Results

CRP levels and WCC counts were substantially higher in patients with GNB. Logistic regression analysis demonstrated that GNB and Acute Physiology and Chronic Health Evaluation (APACHE) II score were independently associated with a CRP increase of 5 mg/dL from d_-2 to d₊₁, and both were also independently associated with an increase of WCC levels from d_-2 to d₊₁ of 5,000 × 10³ cells/mm³.

Conclusion

Increased levels of CRP and WCC are suggestive for GNB, while almost unchanged CRP and WCC levels are observed in patients with GPB. However, despite the different patterns observed, antimicrobial treatment as such cannot be guided based on both biomarkers.

Measuring the impact of multidrug resistance in nosocomial infection

PURPOSE OF REVIEW

The review examines potential confounders hampering measurement of the impact of multidrug resistance in nosocomial infections. Methodological techniques dealing with the problem of confounding are discussed and current findings in how multidrug resistance affects outcome in patients with nosocomial infection are highlighted.

RECENT FINDINGS

Outcome comparisons between patients infected with multidrug-resistant pathogens and patients infected with susceptible microorganisms are hampered by confounders such as differences in disease severity, prolonged hospitalization prior to onset of infection (exposure time), the causative pathogen, the type of infection, and the rate of appropriate empirical antimicrobial therapy. The confounding effect can be countered by means of either multivariable regression techniques or matched cohort studies, or a combination of both. Recent literature on the impact of multidrug resistance (methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum beta-lactamase producing Enterobacteriaceae, etc) is conflicting and highly dependable on the way disturbing variables are accounted for.

SUMMARY

Recent data underscore that the impact of multidrug resistance on the outcome of nosocomial infection might differ depending on the study population, type of infection, type of pathogen and appropriateness of therapy, and hence, that any conclusion drawn prior to accurate accounting for imbalanced confounders is premature and potentially false.

Outcome in bacteremia associated with nosocomial pneumonia and the impact of pathogen prediction by tracheal surveillance cultures

OBJECTIVE

To assess whether pathogen prediction in bacteremia associated with nosocomial pneumonia (NP) by tracheal surveillance cultures improves adequacy of early antibiotic therapy and impacts mortality.

DESIGN AND SETTING

A retrospective observational study of a prospectively gathered cohort. This cohort included all adult patients admitted to the ICU of a tertiary care hospital from 1992 through 2001 and who developed bacteremia associated with NP.

MEASUREMENTS AND MAIN RESULTS

128 episodes of bacteremia associated with NP were identified. In 110 episodes a tracheal surveillance culture 48-96h prior to bacteremia was available: this culture predicted the pathogen in 67 episodes (61%). Overall rates of appropriate empiric antibiotic therapy within 24 and 48h were 62 and 87%, respectively. Pathogen prediction was associated with a significantly higher rate of appropriate antibiotic therapy within 24h (71 vs 45%; p=0.01), but not within 48h (91 vs 82%; p=0.15). Crude in-hospital mortality was 50%. Pathogen prediction was associated with increased survival in univariate (OR 0.43; CI 0.19-0.93; p=0.04) and multivariate analysis (OR 0.32; CI 0.12-0.82; p=0.02). Multivariate analysis further identified age (OR 1.04; CI 1.01-1.07; p=0.02), increasing APACHEII score (OR 1.08; CI 1.02-1.15; p=0.01), and methicillin-resistant Staphylococcus aureus (OR 5.90; CI 1.36-25.36; p=0.01) and Pseudomonas aeruginosa (OR 3.30; CI 1.04-10.4; p=0.04) as independent risk factors for mortality.

CONCLUSION

Pathogen prediction in bacteremia associated with NP by tracheal surveillance cultures is associated with a higher rate of adequate empiric antibiotic therapy within 24[Symbol: see text]h and with increased survival.

Nosocomial pneumonia: aetiology, diagnosis and treatment

PURPOSE OF REVIEW

This review highlights recent advances in the aetiology of nosocomial pneumonia, and in strategies to increase accuracy of diagnosis and antibiotic prescription while limiting unnecessary antibiotic consumption.

RECENT FINDINGS

Bacterial pathogens still cause the bulk of nosocomial pneumonia and are of concern because of ever-rising antimicrobial resistance. Yet, the pathogenic role of fungal and viral organisms is increasingly recognized. Since early appropriate antimicrobial therapy is the cornerstone of an effective treatment, further studies have been conducted to improve appropriateness of early antibiotic therapy. De-escalation strategies combine initial broad-spectrum antibiotics to maximize early antibiotic coverage with a subsequent focusing of the antibiotic spectrum when the cause is identified. Invasive techniques probably do not alter the immediate outcome but have the potential to reduce unnecessary antibiotic exposure. Decisions to stop or change antibiotic therapy are hampered due to a lack of reliable parameters to assess the resolution of pneumonia.

SUMMARY

Increasing antimicrobial resistance in nosocomial pneumonia both challenges treatment and mandates limitation of selection pressure by reducing antibiotic burden. Treating physicians should be both aggressive in initiating antimicrobials when suspecting nosocomial pneumonia but willing to discontinue antimicrobials when diagnostic results point to an alternative diagnosis. Efforts should be made to limit duration of antibiotic therapy when possible.