Relationship between immunosuppression and intensive care unit-acquired multidrug-resistant bacteria: a case-control study

Impact of Immunosuppressed Status on Prognosis of Carbapenem-Resistant Organisms Bloodstream Infections

INTRODUCTION

The impact of immunosuppression on prognosis of carbapenem-resistant organism (CRO) bloodstream infection (BSI) remains unclear. The aim of this study was to clarify the relationship between immunosuppression and mortality of CRO-BSI and to identify the risk factors associated with mortality in immunosuppressed patients.

METHODS

This retrospective study included 279 patients with CRO-BSI from January 2018 to March 2023. Clinical characteristics and outcomes were compared between the immunosuppressed and immunocompetent patients. The relationship between immunosuppression and 30-day mortality after BSI onset was assessed through logistic-regression analysis, propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). Factors associated with mortality in immunosuppressed patients were analyzed using multivariable logistic regression analysis.

RESULTS

A total of 88 immunocompetent and 191 immunosuppressed patients were included, with 30-day all-cause mortality of 58.8%. Although the 30-day mortality in immunosuppressed patients was significantly higher than in immunocompetent patients (46.6% vs. 64.4%, P = 0.007), immunosuppression was not an independent risk factor for mortality in multivariate logistic regression analysis (odds ratio [OR] 3.53, 95% confidence interval [CI] 0.74-18.89; P = 0.123), PSM (OR 1.38, 95% CI 0.60-3.18; P = 0.449,) or IPTW (OR 1.40, 95% CI 0.58-3.36; P = 0.447). For patients with CRO-BSI, regardless of immune status, appropriate antibiotic therapy was associated with decreased 30-day mortality, while Charlson comorbidity index (CCI), intensive care unit (ICU)-acquired infection and thrombocytopenia at CRO-BSI onset were associated with increased mortality.

CONCLUSION

Despite the high mortality rate of CRO-BSI, immunosuppression did not affect the mortality. Appropriate antibiotic therapy is crucial for improving the prognosis of CRO-BSI, regardless of the immune status.

ICU-acquired infections in immunocompromised patients

Immunocompromised patients account for an increasing proportion of the typical intensive care unit (ICU) case-mix. Because of the increased availability of new drugs for cancer and auto-immune diseases, and improvement in the care of the most severely immunocompromised ICU patients (including those with hematologic malignancies), critically ill immunocompromised patients form a highly heterogeneous patient population. Furthermore, a large number of ICU patients with no apparent immunosuppression also harbor underlying conditions altering their immune response, or develop ICU-acquired immune deficiencies as a result of sepsis, trauma or major surgery. While infections are associated with significant morbidity and mortality in immunocompromised critically ill patients, little specific data are available on the incidence, microbiology, management and outcomes of ICU-acquired infections in this population. As a result, immunocompromised patients are usually excluded from trials and guidelines on the management of ICU-acquired infections. The most common ICU-acquired infections in immunocompromised patients are ventilator-associated lower respiratory tract infections (which include ventilator-associated pneumonia and tracheobronchitis) and bloodstream infections. Recently, several large observational studies have shed light on some of the epidemiological specificities of these infections-as well as on the dynamics of colonization and infection with multidrug-resistant bacteria-in these patients, and these will be discussed in this review. Immunocompromised patients are also at higher risk than non-immunocompromised hosts of fungal and viral infections, and the diagnostic and therapeutic management of these infections will be covered. Finally, we will suggest some important areas of future investigation.

Ventilator-Associated Pneumonia in Immunosuppressed Patients

Immunocompromised patients-including patients with cancer, hematological malignancies, solid organ transplants and individuals receiving immunosuppressive therapies for autoimmune diseases-account for an increasing proportion of critically-ill patients. While their prognosis has improved markedly in the last decades, they remain at increased risk of healthcare- and intensive care unit (ICU)-acquired infections. The most frequent of these are ventilator-associated lower respiratory tract infections (VA-LTRI), which include ventilator-associated pneumonia (VAP) and tracheobronchitis (VAT). Recent studies have shed light on some of the specific features of VAP and VAT in immunocompromised patients, which is the subject of this narrative review. Contrary to previous belief, the incidence of VAP and VAT might actually be lower in immunocompromised than non-immunocompromised patients. Further, the relationship between immunosuppression and the incidence of VAP and VAT related to multidrug-resistant (MDR) bacteria has also been challenged recently. Etiological diagnosis is essential to select the most appropriate treatment, and the role of invasive sampling, specifically bronchoscopy with bronchoalveolar lavage, as well as new molecular syndromic diagnostic tools will be discussed. While bacteria-especially gram negative bacteria-are the most commonly isolated pathogens in VAP and VAT, several opportunistic pathogens are a special concern among immunocompromised patients, and must be included in the diagnostic workup. Finally, the impact of immunosuppression on VAP and VAT outcomes will be examined in view of recent papers using improved statistical methodologies and treatment options-more specifically empirical antibiotic regimens-will be discussed in light of recent findings on the epidemiology of MDR bacteria in this population.

Relationship between immunosuppression and intensive care unit-acquired colonization and infection related to multidrug-resistant bacteria: a prospective multicenter cohort study

PURPOSE

The impact of immunosuppression on intensive care unit (ICU)-acquired colonization and infection related to multidrug-resistant (MDR) bacteria (ICU-MDR-col and ICU-MDR-inf, respectively) is unknown.

METHODS

We carried out an observational prospective cohort study in 8 ICUs in France (all with single-bed rooms and similar organizational characteristics). All consecutive patients with an ICU stay > 48 h were included, regardless of immune status, and followed for 28 days. Patients underwent systematic screening for colonization with MDR bacteria upon admission and every week subsequently. Immunosuppression was defined as active cancer or hematologic malignancy, neutropenia, solid-organ transplant, use of steroids or immunosuppressive drugs, human immunodeficiency virus infection and genetic. The primary endpoint was the incidence rate of a composite outcome including ICU-MDR-col and/or ICU-MDR-inf.

RESULTS

750 patients (65.9% males, median age 65 years) were included, among whom 264 (35.2%) were immunocompromised. Reasons for ICU admission, severity scores and exposure to invasive devices and antibiotics during ICU stay were comparable between groups. After adjustment for center and pre-specified baseline confounders, immunocompromised patients had a lower incidence rate of ICU-MDR-col and/or ICU-MDR-inf (adjusted incidence ratio 0.68, 95% CI 0.52-0.91). When considered separately, the difference was significant for ICU-MDR-col, but not for ICU-MDR-inf. The distribution of MDR bacteria was comparable between groups, with a majority of Enterobacteriacae resistant to third-generation cephalosporins (~ 74%).

CONCLUSION

Immunocompromised patients had a significantly lower incidence rate of a composite outcome including ICU-MDR-col and/or ICU-MDR-inf. This finding points to the role of contact precautions and isolation measures, and could have important implications on antibiotic stewardship in this population.

Catestatin in innate immunity and Cateslytin-derived peptides against superbugs

Chromogranin A (CgA) is the precursor of several antimicrobial peptides, such as Catestatin (Cts, bovine CgA344-364), initially described as a potent inhibitor of catecholamines. This peptide displays direct antimicrobial activities and contributes to immune system regulation. The aim of the present study is to investigate a designed peptide based on Cts to fight infections against superbugs and more particularly Staphylococcus aureus. In addition to Cateslytin (Ctl, bovine CgA344-358), the active domain of Catestatin, several peptides including dimers, D-isomer and the new designed peptide DOPA-K-DOPA-K-DOPA-TLRGGE-RSMRLSFRARGYGFR (Dopa5T-Ctl) were prepared and tested. Cateslytin is resistant to bacterial degradation and does not induce bacterial resistance. The interaction of Catestatin with immune dermal cells (dendritic cells DC1a, dermal macrophages CD14 and macrophages) was analyzed by using confocal microscopy and cytokine release assay. The dimers and D-isomer of Ctl were tested against a large variety of bacteria showing the potent antibacterial activity of the D-isomer. The peptide Dopa5T-Ctl is able to induce the self-killing of S. aureus after release of Ctl by the endoprotease Glu-C produced by this pathogen. It permits localized on-demand delivery of the antimicrobial drug directly at the infectious site.

Acute respiratory failure in immunosuppressed patients admitted to ICU

INTRODUCTION

The number of hospitalized immunosuppressed adults is a growing and often develop severe complications that require admission to an Intensive Care Unit (ICU). The main cause of admission is acute respiratory failure (ARF). The goal of the study was to determine if ARF represents an independent risk factor for hospital mortality and in particular, we sought to ascertain if any risk factors were independently and identifiably associated with a bad outcome.

METHODS

We perform a retrospective study of a prospectively collected data from patients admitted to an ICU. Adult patients with known immunosuppressive condition admitted to ICU were included.

RESULTS

A total of 248 patients were included. Of 248 patients, 117 (47.2%) had a diagnosis of ARF at the time of ICU admission. Patients with ARF had a significantly higher in-hospital mortality (53.4% vs. 28.2% p = 0.001). Factors independently associated with hospital mortality were diagnosis of ARF at ICU admission, the presence of septic shock, use of continuous renal replacement therapy and failure of high-flow nasal canula(HFNC)/non-invasive (NIV) respiratory therapies.

CONCLUSION

We identified ARF on admission and failure of HFNC/NIV to be independently associated with increased hospital mortality in immunosuppressed patients.

Vancomycin-Lipopeptide Conjugates with High Antimicrobial Activity on Vancomycin-Resistant Enterococci

Multidrug-resistant bacteria represent one of the most important health care problems worldwide. While there are numerous drugs available for standard therapy, there are only a few compounds capable of serving as a last resort for severe infections. Therefore, approaches to control multidrug-resistant bacteria must be implemented. Here, a strategy of reactivating the established glycopeptide antibiotic vancomycin by structural modification with polycationic peptides and subsequent fatty acid conjugation to overcome the resistance of multidrug-resistant bacteria was followed. This study especially focuses on the structure-activity relationship, depending on the modification site and fatty acid chain length. The synthesized conjugates showed high antimicrobial potential on vancomycin-resistant enterococci. We were able to demonstrate that the antimicrobial activity of the vancomycin-lipopeptide conjugates depends on the chain length of the attached fatty acid. All conjugates showed good cytocompatibility in vitro and in vivo. Radiolabeling enabled the in vivo determination of pharmacokinetics in Wistar rats by molecular imaging and biodistribution studies. An improved biodistribution profile in comparison to unmodified vancomycin was observed. While vancomycin is rapidly excreted by the kidneys, the most potent conjugate shows a hepatobiliary excretion profile. In conclusion, these results demonstrate the potential of the structural modification of already established antibiotics to provide highly active compounds for tackling multidrug-resistant bacteria.

Clinical Usefulness of Bronchoalveolar Lavage in the Management of Pulmonary Infiltrates in Adults with Hematological Malignancies and Stem Cell Transplantation

Introduction

Pulmonary complications are frequent in patients with hematologic malignancies and stem cell transplantation. Regardless of the microbiological usefulness of bronchoalveolar lavage (BAL), little information exists on both its benefits as a guide for therapeutic decisions and its impact on patients’ clinical outcome.

Methods

A prospective observational single-center study was performed between July 2011 and July 2016. Consecutive episodes of pulmonary infiltrates were analyzed in subjects over 18 years of age who presented hematologic malignancies and underwent chemotherapy or stem cell transplantation.

Results

Ninety-six episodes of pulmonary infiltrates were analyzed. Acute leukemia was the most frequent underlying condition. Thirty-seven patients (38.5%) received a stem cell transplant. Sixty-one (62.9%) were neutropenic at the moment of inclusion in the study. A definitive etiologic diagnosis was obtained in 41 cases (42.7%), where infection accounted for the vast majority of cases (33 cases, 80.5%). Definitive diagnosis was reached by non-invasive methods in 13 cases (13.5%). BAL was performed in 47 cases and led to a diagnosis in 40.4% of the cases. BAL results led to therapeutic changes in 27 cases (57.4%), including the addition of new antimicrobials to empiric treatments in 10. Regarding BAL’s safety, two patients experienced minor adverse events and one a severe adverse event; no procedure-related deaths were observed.

Conclusions

Infection was the leading cause of pulmonary infiltrates in patients with hematologic malignancies and stem cell transplantation. BAL was a useful decision-making diagnostic tool, with minor adverse events.

Clinical Features, Outcomes, and Risk Factors of Bloodstream Infections due to Stenotrophomonas maltophilia in a Tertiary-Care Hospital of China: A Retrospective Analysis

Background. Stenotrophomonas maltophilia bacteremia (SMB) is the most perilous situation as compared to other types of S. maltophilia infection. The present study aimed to investigate the clinical features, distribution, drug resistance, and predictors of survival of SMB in a tertiary-care hospital of China. Methods. SMB that occurred in a tertiary-care hospital in Beijing, China, within 9 years (2010-2018) was investigated in a retrospective study. Demographics, incidence, commodities, drug resistance, mortality, as well as antibiotics administration were summarized according to the electronic medical records. The risk factors for survival were analyzed by Chi-square test, Kaplan-Meier curve and Cox regression. Results. A total of 76 episodes of SMB were analyzed. The overall incidence of SMB fluctuated from 3.4 to 15.4 episodes per 1000 admissions over 9 years. Malignancy was the most common comorbidity. High in vitro sensitivity was observed to minocycline (96.1%), levofloxacin (81.6%), and trimethoprim-sulfamethoxazole (89.5%). Central venous catheter (CVC) (p = 0.004), mechanical ventilation (MV) (p = 0.006), hemodialysis (p = 0.024), and septic shock (p = 0.016) were significantly different between survival and death group. The 30-day mortality was 34.2% within 30 days after confirmation of blood culture. Factors such as hemodialysis (OR 0.287, 95% CI: 0.084-0.977, p = 0.046), T-tube (OR 0.160, 95% CI: 0.029-0.881, p = 0.035), and septic shock (OR 0.234, 95% CI: 0.076-0.719, p = 0.011) were associated with survival. Conclusions. S. maltophilia is the major nosocomial blood stream infectious pathogenic bacteria. Trimethoprim-sulfamethoxazole and minocycline are optimal antibiotics for the treatment of SMB. T-tube, hemodialysis, and septic shock were the risk factors associated with survival of SMB patients.

Influenza and associated co-infections in critically ill immunosuppressed patients

BACKGROUND

It is unclear whether influenza infection and associated co-infection are associated with patient-important outcomes in critically ill immunocompromised patients with acute respiratory failure.

METHODS

Preplanned secondary analysis of EFRAIM, a prospective cohort study of 68 hospitals in 16 countries. We included 1611 patients aged 18 years or older with non-AIDS-related immunocompromise, who were admitted to the ICU with acute hypoxemic respiratory failure. The main exposure of interest was influenza infection status. The primary outcome of interest was all-cause hospital mortality, and secondary outcomes ICU length of stay (LOS) and 90-day mortality.

RESULTS

Influenza infection status was categorized into four groups: patients with influenza alone (n = 95, 5.8%), patients with influenza plus pulmonary co-infection (n = 58, 3.6%), patients with non-influenza pulmonary infection (n = 820, 50.9%), and patients without pulmonary infection (n = 638, 39.6%). Influenza infection status was associated with a requirement for intubation and with LOS in ICU (P < 0.001). Patients with influenza plus co-infection had the highest rates of intubation and longest ICU LOS. On crude analysis, influenza infection status was associated with ICU mortality (P < 0.001) but not hospital mortality (P = 0.09). Patients with influenza plus co-infection and patients with non-influenza infection alone had similar ICU mortality (41% and 37% respectively) that was higher than patients with influenza alone or those without infection (33% and 26% respectively). A propensity score-matched analysis did not show a difference in hospital mortality attributable to influenza infection (OR = 1.01, 95%CI 0.90-1.13, P = 0.85). Age, severity scores, ARDS, and performance status were all associated with ICU, hospital, and 90-day mortality.

CONCLUSIONS

Category of infectious etiology of respiratory failure (influenza, non-influenza, influenza plus co-infection, and non-infectious) was associated with ICU but not hospital mortality. In a propensity score-matched analysis, influenza infection was not associated with the primary outcome of hospital mortality. Overall, influenza infection alone may not be an independent risk factor for hospital mortality in immunosuppressed patients.

Treatment of Pseudomonas aeruginosa Biofilm Present in Endotracheal Tubes by Poly-l-Lysine

The endotracheal tube (ETT) is an essential interface between the patient and ventilator in mechanically ventilated patients. However, a microbial biofilm is formed gradually on this tube and is associated with the development of ventilator-associated pneumonia. The bacteria present in the biofilm are more resistant to antibiotics, and current medical practices do not make it possible to eliminate. Pseudomonas aeruginosa is one of the leading pathogens that cause biofilm infections and ventilator-associated pneumonia. Poly-l-lysine (pLK) is a cationic polypeptide possessing antibacterial properties and mucolytic activity by compacting DNA. Here, we explored the antibiofilm activity of pLK to treat P. aeruginosa biofilms on ETTs while taking into consideration the necessary constraints for clinical translation in our experimental designs. First, we showed that pLK eradicates a P. aeruginosa biofilm formed in vitro on 96-well microplates. We further demonstrated that pLK alters bacterial membrane integrity, as revealed by scanning electron microscopy, and eventually eradicates biofilm formed either by reference or clinical strains of P. aeruginosa biofilms generated in vitro on ETTs. Second, we collected the ETT from patients with P. aeruginosa ventilator-associated pneumonia. We observed that a single dose of pLK is able to immediately disrupt the biofilm structure and kills more than 90% of bacteria present in the biofilm. Additionally, we did not observe any lung tolerance issue when the pLK solution was instilled into the ETT of ventilated pigs, an animal model particularly relevant to mimic invasive mechanical ventilation in humans. In conclusion, pLK appears as an innovative antibiofilm molecule, which could be applied in the ETT of mechanically ventilated patients.

Restoration of T Cell function in multi-drug resistant bacterial sepsis after interleukin-7, anti-PD-L1, and OX-40 administration

BACKGROUND

Multidrug resistant (MDR) bacterial pathogens are a serious problem of increasing importance facing the medical community. MDR bacteria typically infect the most immunologically vulnerable: patients in intensive care units, patients with extensive comorbidities, oncology patients, hemodialysis patients, and other immune suppressed individuals are likely to fall victim to these pathogens. One promising novel approach to treatment of MDR bacteria is immuno-adjuvant therapy to boost patient immunity. Success with this strategy would have the major benefit of providing protection against a number of MDR pathogens.

OBJECTIVES

This study had two main objectives. First, immunophenotyping of peripheral blood mononuclear cells from patients with sepsis associated with MDR bacteria was performed to examine for findings indicative of immunosuppression. Second, the ability of three immuno-adjuvants with distinct mechanisms of action to reverse CD4 and CD8 T cell dysfunction, a pathophysiological hallmark of sepsis, was evaluated.

RESULTS

Septic patients with MDR bacteria had increased expression of the inhibitory receptor PD-1 and its ligand PD-L1 and decreased monocyte HLA-DR expression compared to non-septic patients. All three immuno-adjuvants, IL-7, anti-PD-L1, and OX-40L, increased T cell production of IFN-γ in a subset of septic patients with MDR bacteria: IL-7 was most efficacious. There was a strong trend toward increased mortality in patients whose T cells failed to increase IFN-γ production in response to the three treatments.

CONCLUSION

Immuno-adjuvant therapy reversed T cell dysfunction, a key pathophysiological mechanism in septic patients with MDR bacteria.

Methicillin-resistant Staphylococcus aureus nasal carriage and infection among patients with diabetic foot ulcer

PURPOSE

To evaluate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage in patients with diabetic foot ulcer (DFU) in Taiwan, and to assess the concordance between colonizing and clinical MRSA isolates from the patients.

METHOD

A total of 354 nasal specimens were collected from 112 to 242 diabetic patients with and without foot ulcer, respectively. MRSA clinical isolates from DFU wound cultures were collected for comparison.

RESULTS

Nasal carriage rate of S. aureus and MRSA was similar between diabetic patients with and without foot ulcer (15.2% vs. 16.9% for S. aureus and 5.4% vs. 1.7% for MRSA). Nasal S. aureus colonization was an independent predictor for wound S. aureus infection (Odds ratio [OR]: 5.33, 95% confidence interval [CI]: 1.61-17.59), so did nasal MRSA colonization (OR: 19.09, 95% CI: 2.12-171.91). The levels of glycated hemoglobin, and the usage with immunosuppressant agent were associated with S. aureus nasal colonization while oral hypoglycemic agent usage a protective factor. Sequence type 59/staphylococcal chromosome cassette mec IV or V, the local endemic community-associated clone, accounted for 42% and 70% of the clinical and colonizing isolates, respectively. Six of 10 patients with paired colonizing and clinical isolates, either MRSA or methicillin-sensitive S. aureus, had a genetically identical strain from a single patient.

CONCLUSION

Less than one-fifth of patients with DFU have nasal S. aureus, including MRSA, colonization; however, the colonization is significantly associated with S. aureus diabetic foot infection. Screening for S. aureus colonizing status in DFU patients might have a potential clinical implication.

Distinct T-helper cell responses to Staphylococcus aureus bacteremia reflect immunologic comorbidities and correlate with mortality

BACKGROUND

The dysregulated host immune response that defines sepsis varies as a function of both the immune status of the host and the distinct nature of the pathogen. The degree to which immunocompromising comorbidities or immunosuppressive medications affect the immune response to infection is poorly understood because these patients are often excluded from studies about septic immunity. The objectives of this study were to determine the immune response to a single pathogen (Staphylococcus aureus) among a diverse case mix of patients and to determine whether comorbidities affect immune and clinical outcomes.

METHODS

Blood samples were drawn from 95 adult inpatients at multiple time points after the first positive S. aureus blood culture. Cox proportional hazards modeling was used to determine the associations between admission neutrophil counts, admission lymphocyte counts, cytokine levels, and 90-day mortality. A nested case-control flow cytometric analysis was conducted to determine T-helper type 1 (Th1), Th2, Th17, and regulatory T-cell (Treg) subsets among a subgroup of 28 patients. In a secondary analysis, we categorized patients as either having immunocompromising disorders (human immunodeficiency virus and hematologic malignancies), receiving immunosuppressive medications, or being not immunocompromised.

RESULTS

Higher neutrophil-to-lymphocyte count ratios and higher Th17 cytokine responses relative to Th1 cytokine responses early after infection were independently associated with mortality and did not depend on the immune state of the patient (HR 1.93, 95% CI 1.17-3.17, p = 0.01; and HR 1.13, 95% CI 1.01-1.27, p = 0.03, respectively). On the basis of flow cytometric analysis of CD4 T-helper subsets, an increasing Th17/Treg response over the course of the infection was most strongly associated with increased mortality (HR 4.41, 95% CI 1.69-11.5, p < 0.01). This type of immune response was most common among patients who were not immunocompromised. In contrast, among immunocompromised patients who died, a decreasing Th1/Treg response was most common.

CONCLUSIONS

The association of both increased Th17 responses and increased neutrophil counts relative to lymphocyte counts with mortality suggests that an overwhelming inflammatory response is detrimental. However, the differential responses of patients according to immune state suggest that immune status is an important clinical indicator that should be accounted for in the management of septic patients, as well as in the development of novel immunomodulatory therapies.

Impact of immunosuppression on incidence, aetiology and outcome of ventilator-associated lower respiratory tract infections

The aim of this planned analysis of the prospective multinational TAVeM database was to determine the incidence, aetiology and impact on outcome of ventilator-associated lower respiratory tract infections (VA-LRTI) in immunocompromised patients.All patients receiving mechanical ventilation for >48 h were included. Immunocompromised patients (n=663) were compared with non-immunocompromised patients (n=2297).The incidence of VA-LRTI was significantly lower among immunocompromised than among non-immunocompromised patients (16.6% versus 24.2%; sub-hazard ratio 0.65, 95% CI 0.53-0.80; p<0.0001). Similar results were found regarding ventilator-associated tracheobronchitis (7.3% versus 11.6%; sub-hazard ratio 0.61, 95% CI 0.45-0.84; p=0.002) and ventilator-associated pneumonia (9.3% versus 12.7%; sub-hazard ratio 0.72, 95% CI 0.54-0.95; p=0.019). Among patients with VA-LRTI, the rates of multidrug-resistant bacteria (72% versus 59%; p=0.011) and intensive care unit mortality were significantly higher among immunocompromised than among non-immunocompromised patients (54% versus 30%; OR 2.68, 95% CI 1.78-4.02; p<0.0001). In patients with ventilator-associated pneumonia, mortality rates were higher among immunocompromised than among non-immunocompromised patients (64% versus 34%; p<0.001).Incidence of VA-LRTI was significantly lower among immunocompromised patients, but it was associated with a significantly higher mortality rate. Multidrug-resistant pathogens were more frequently found in immunocompromised patients with VA-LRTI.

Multi-drug resistant organism infections in a medical ICU: Association to clinical features and impact upon outcome

OBJECTIVE

To define clinical features associated with Intensive Care Unit (ICU) infections caused by multi-drug resistant organisms (MDRO) and their impact on patient outcome.

DESIGN

A single-center, retrospective case-control study was carried out between January 2010 and May 2010.

SETTING

A medical ICU (MICU) in the United States.

PATIENTS

The study included a total of 127 MDRO-positive patients and 186 MDRO-negative patients.

INTERVENTIONS

No interventions were carried out.

RESULTS

Out of a total of 313 patients, MDROs were present in 127 (41.7%). Based on the multivariate analysis, only infection as a cause of admission [OR 3.3 (1.9-5.8)]), total days of ventilation [OR 1.07 (1.01-1.12)], total days in hospital [OR 1.04 (1.01-1.07)], immunosuppression [OR 2.04 (1.2-3.5)], a history of hyperlipidemia [OR 2.2 (1.2-3.8)], surgical history [OR 1.82 (1.05-3.14)] and age [OR 1.02 (1.00-1.04)] were identified as clinical factors independently associated to MDROs, while the Caucasian race was negatively associated to MDROs. The distribution of days on ventilation, days in hospital and days of antibiotic treatment prior to infection differed between the MDRO-positive and MDRO-negative groups. The MDRO-positive patients showed a greater median number of days in hospital and days of antibiotic treatment before infection, with a greater median number of days in hospital, days of antibiotic treatment and days of ventilation after infection, compared to the MDRO-negative patients. The mortality rate was not significantly different between the two groups. Appropriate empirical antibiotic therapy was prescribed in 82% of the MDRO-positive cases - such treatment being started within 24h after onset of the infection in 68.5% of the cases.

CONCLUSION

Defining clinical factors associated with MDRO infections and administering timely and appropriate empirical antibiotic therapy may help reduce the mortality associated with these infections. In our hospital we did not withhold broad spectrum drugs as empirical therapy in patients with clinical features associated to MDRO infection. Our rate of appropriate empirical therapy was therefore high, which could explain the absence of excessive mortality in patients infected with MDROs.

Pseudomonas aeruginosa proteolytically alters the interleukin 22-dependent lung mucosal defense

The IL-22 signaling pathway is critical for regulating mucosal defense and limiting bacterial dissemination. IL-22 is unusual among interleukins because it does not directly regulate the function of conventional immune cells, but instead targets cells at outer body barriers, such as respiratory epithelial cells. Consequently, IL-22 signaling participates in the maintenance of the lung mucosal barrier by controlling cell proliferation and tissue repair, and enhancing the production of specific chemokines and anti-microbial peptides. Pseudomonas aeruginosa is a major pathogen of ventilator-associated pneumonia and causes considerable lung tissue damage. A feature underlying the pathogenicity of this bacterium is its capacity to persist and develop in the host, particularly in the clinical context of nosocomial lung infections. We aimed to investigate the ability of P. auruginosa to disrupt immune-epithelial cells cross-talk. We found that P. aeruginosa escapes the host mucosal defenses by degrading IL-22, leading to severe inhibition of IL-22-mediated immune responses. We demonstrated in vitro that, protease IV, a type 2 secretion system-dependent serine protease, is responsible for the degradation of IL-22 by P. aeruginosa. Moreover, the major anti-proteases molecules present in the lungs were unable to inhibit protease IV enzymatic activity. In addition, tracheal aspirates of patients infected by P. aeruginosa contain protease IV activity which further results in IL-22 degradation. This so far undescribed cleavage of IL-22 by a bacterial protease is likely to be an immune-evasion strategy that contributes to P. aeruginosa-triggered respiratory infections.

Fournier's Gangrene: Lessons Learned from Multimodal and Multidisciplinary Management of Perineal Necrotizing Fasciitis

Background

Fournier’s gangrene (FG) is a rapidly evolving necrotizing fasciitis of the perineum and the genital area, the scrotum as it most commonly affects man in the vast majority of cases. It is polymicrobial in origin, due to the synergistic action of anaerobes and aerobes and has a very high mortality. There are many predisposing factors including diabetes mellitus, alcoholism, immunosuppression, renal, and hepatic disease. The prognosis of the disease depends on a lot of factors including but not limited to patient age, disease extent, and comorbidities. The purpose of the study is to describe the experience of a general surgery department in the management of FG, to present the multimodal and multidisciplinary treatment of the disease, to identify predictors of mortality, and to make general surgeons familiar with the disease.

Methods

The current retrospective study is presenting the experience of our general surgery department in the management of FG during the last 20 years. The clinical presentation and demographics of the patients were recorded. Also we recorded the laboratory data, the comorbidities, the etiology, and microbiology and the therapeutic interventions performed, and we calculated the various severity indexes. Patients were divided to survivors and non-survivors, and all the collected data were statistically analyzed to assess mortality factors using univariate and then multivariate analysis.

Results

In our series, we treated a total of 24 patients with a mean age 58.9 years including 20 males (83.4%) and 4 females (16.6%). In most patients, a delay between disease onset and seeking of medical help was noted. Comorbidities were present in almost all patients (87.5%). All patients were submitted to extensive surgical debridements and received broad-spectrum antibiotics until microbiological culture results were received. Regarding all the collected data, there was no statistically significant difference between survivors and non-survivors except the presence of malignancy in non-survivors (p = 0.036) and the lower hemoglobin (p < 0.001) and hematocrit (p = 0.002) in non-survivors. However, multivariate analysis did not reveal any predictor of mortality.

Conclusion

Early diagnosis, aggressive thorough surgical treatment, and administration of the proper antibiotic treatment comprise the cornerstone for the outcome of this disease. In small populations like in the present study, it is difficult to recognize any predictors of mortality and even the severity indexes, which take into account a lot of data cannot predict mortality.

Clinical Characteristics of Stenotrophomonas maltophilia Bacteremia: A Regional Report and a Review of a Japanese Case Series

Objective Stenotrophomonas maltophilia is an emerging nosocomial pathogen that causes fatal infections in critically ill or immunocompromised patients. S. maltophilia bacteremia (SMB) is a rare condition, and its clinical characteristics in Japanese settings are not well known. Methods The medical charts of patients with SMB were retrospectively reviewed at two medical facilities (Okayama University Hospital and Tsuyama Chuo Hospital) for seven years. The data were analyzed along with those previously reported from other Japanese facilities. Result A total of 181 patients (110 men and 71 women) were evaluated. The major underlying diseases included hematologic malignancy (36.5%), solid organ malignancy (25.4%), and neutropenia (31.5%). The recent use of carbapenem was seen in 56.9% of the cases in total, and more than one-third of the patients in our hospitals were treated with carbapenem at the onset of SMB. Of 28 (63.6%) of 44 cases treated for S. maltophilia, those who did not survive were more likely to have been treated with broad-spectrum antibiotics. A multivariate analysis revealed that a higher updated Charlson Comorbidity Index [odds ratio (95% confidence interval), 1.75 (1.11-2.75); p=0.015] and intubation [odds ratio (95% confidence interval), 12.6 (1.62-97.9); p=0.016] were associated with mortality in our cases. Pathogens were often resistant to ceftazidime but susceptible to minocycline, trimethoprim/sulfamethoxazole, and fluoroquinolones. The overall mortality rates within 30 and 90 days were 37.5% and 62.5%, respectively. Conclusion The clinical characteristics of SMB in Japanese cases were similar to those reported from other countries. Clinicians should be aware that breakthrough infection by S. maltophilia may occur during administration of carbapenem.

Combatting resistance in intensive care: the multimodal approach of the Spanish ICU "Zero Resistance" program

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2015 and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/annualupdate2015. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Diagnostic value of bronchoscopy in patients with hematologic malignancy and pulmonary infiltrates

Pulmonary infections are a major cause of morbidity and mortality in patients with hematologic malignancy. Bronchoscopy is at present still the traditional first investigation in immunosuppressed patients that have developed pulmonary infiltrates. There is limited data available on the validity of fiberoptic bronchoscopy (FOB) with bronchoalveolar lavage (BAL) to determine the etiology of pulmonary infiltrates with concurrent hematologic malignancy. We retrospectively analyzed the microbiological results of 206 bronchoscopic examinations and treatment changes used in 187 patients with hematologic malignancy and pulmonary infiltrates. Bacteria, fungi, and viruses were found in 85 (41.3 %), 49 (23.8 %), and 55 (28.6 %) of cases, respectively, and overall yield of bronchoscopy was 65.0 %. We compared the microbiological findings with respect to neutropenia, hematopoietic stem cell transplantation (HSCT) status, and the type of malignancy. There were significantly more bacterial and viral infections detected in post-HSCT patients, and more viruses were detected in patients without neutropenia. Galactomannan (GM) was measured in 149 BAL samples. With a GM index threshold of ≥0.5, the sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) of the BAL GM assay were 93.94 %, 86.21 %, 65.96 %, and 98.04 %, respectively. Treatment was modified in 62 cases (30.1 %). There was no significant relationship of treatment modification with the underlying disease, HSCT, or neutropenia. Bronchoscopy with BAL is a valuable diagnostic tool to determine the etiology and appropriate treatment in patients with hematologic malignancy and pulmonary infiltrates. A BAL GM test is recommended when invasive pulmonary aspergillosis is suspected.

Risk factors for tracheobronchial acquisition of resistant Gram-negative bacterial pathogens in mechanically ventilated ICU patients

The aim of this study was to identify risk factors for tracheobronchial acquisition with the most common resistant Gram-negative bacteria in the intensive care unit (ICU) during the first week after intubation and mechanical ventilation. Tracheobronchial and oropharyngeal cultures were obtained at admission, after 48 hours, and after 7 days of mechanical ventilation. Patient characteristics, interventions, and antibiotic usage were recorded. Among 71 eligible patients with two negative bronchial cultures for resistant Gram-negative bacteria (at admission and within 48 hours), 41 (58%) acquired bronchial resistant Gram-negative bacteria by day 7. Acquisition strongly correlated with presence of the same pathogens in the oropharynx: Acinetobacter baumannii [odds ratio (OR) = 20·2, 95% confidence interval (CI): 5·5-73·6], Klebsiella pneumoniae (OR = 8·0, 95% CI: 1·9-33·6), and Pseudomonas aeruginosa (OR = 27, 95%: CI 2·7-273). Bronchial acquisition with resistant K. pneumoniae also was associated with chronic liver disease (OR = 3·9, 95% CI: 1·0-15·3), treatment with aminoglycosides (OR = 4·9, 95% CI: 1·4-18·2), tigecycline (OR = 4·9, 95% CI: 1·4-18·2), and linezolid (OR = 3·9, 95% CI: 1·1-15·0). In multivariate analysis, treatment with tigecycline and chronic liver disease were independently associated with bronchial resistant K. pneumoniae acquisition. Our results show a high incidence of tracheobronchial acquisition with resistant Gram-negative microorganisms in the bronchial tree of newly intubated patients. Oropharynx colonization with the same pathogens and specific antibiotics use were independent risk factors.

Impact of appropriate antimicrobial treatment on transition from ventilator-associated tracheobronchitis to ventilator-associated pneumonia

Introduction

Two small randomized controlled trials have suggested beneficial effects of antibiotic treatment in patients with ventilator-associated tracheobronchitis (VAT). The primary aim of this study is to determine the impact of appropriate antibiotic treatment on transition from VAT to ventilator-associated pneumonia (VAP) in critically ill patients. The secondary objective was to determine the incidence of VAP in patients with VAT.

Methods

This was a prospective observational multicenter study. All patients with a first episode of VAT were eligible. Patients with tracheostomy at intensive care unit (ICU) admission, and those with VAP prior to VAT were excluded. VAT was defined using all the following criteria: fever > 38°C with no other cause, purulent tracheal secretions, positive tracheal aspirate (≥10⁵ cfu/mL), and absence of new infiltrate on chest X ray. Only VAP episodes diagnosed during the 96 h following VAT, and caused by the same bacteria, were taken into account. Antibiotic treatment was at the discretion of attending physicians. Risk factors for transition from VAT to VAP were determined using univariate and multivariate analysis. All variables from univariate analysis with P values <0.1 were incorporated in the multivariate logistic regression analysis.

Results

One thousand seven hundred and ten patients were screened for this study. Eighty-six, and 123 patients were excluded for tracheostomy at ICU admission, and VAP prior to VAT; respectively. One hundred and twenty two (7.1%) patients were included. 17 (13.9%) patients developed a subsequent VAP. The most common microorganisms in VAT patients were Pseudomonas aeruginosa (30%), Staphylococcus aureus (18%), and Acinetobacter baumannii (10%). Seventy-four (60%) patients received antimicrobial treatment, including 58 (47.5%) patients who received appropriate antimicrobial treatment. Appropriate antibiotic treatment was the only factor independently associated with reduced risk for transition from VAT to VAP (OR [95% CI] 0.12[0.02-0.59], P = 0.009). The number of patients with VAT needed to treat to prevent one episode of VAP, or one episode of VAP related to P. aeruginosa was 5, and 34; respectively.

Conclusions

Appropriate antibiotic treatment is independently associated with reduced risk for transition from VAT to VAP.

Risk factors for drug-resistant bloodstream infections in patients with systemic lupus erythematosus

OBJECTIVE

To identify risk factors for developing drug-resistant bacterial infections in patients with systemic lupus erythematosus (SLE).

METHODS

A retrospective, case-control study was performed. Patients fulfilled American College of Rheumatology criteria for SLE and had an episode of bloodstream infection between 2001 and 2012. Cases were defined as those with bloodstream infection caused by drug-resistant bacteria (Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, or extended-spectrum-β-lactalamase-producing Escherichia coli); while controls had susceptible strains of S. aureus or E. coli. Differences between groups were analyzed by Student t test or Mann-Whitney U test. Association between variables was assessed by OR (CI 95%). Multivariate analysis was performed by binary logistic regression model.

RESULTS

Forty-four patients were included in each group. Variables associated with drug-resistant bloodstream infection were history of central nervous system activity; hematological activity, immunosuppressive treatment and prednisone dose at the time of the infection; and low C3 levels, antibiotic use, or hospitalization in the previous 3 months. In multivariate analysis, variables that remained significant were low C3 previous to infection (OR 3.12, CI 95% 1.91-8.22), previous hospitalization (OR 2.22, CI 95% 1.42-4.10), and prednisone dose at the time of infection (OR 1.10, CI 95% 1.04-1.22).

CONCLUSION

Low C3 levels, recent hospitalization, and prednisone dose at time of infection are independent risk factors for acquiring drug-resistant bacteria in patients with SLE. Although the present data do not fully support a change in initial treatment-decision strategies, this information could lead to prospective studies designed to address this issue, which could determine the best approach in clinical practice.

Risk factors and outcomes of infections caused by extremely drug-resistant gram-negative bacilli in patients hospitalized in intensive care units

BACKGROUND

Extremely drug-resistant gram-negative bacilli (XDR-GNB) increasingly cause health care-associated infections (HAIs) in intensive care units (ICUs).

METHODS

A matched case-control (1:2) study was conducted from February 2007 to January 2010 in 16 ICUs. Case and control subjects had HAIs caused by GNB susceptible to ≤1 antibiotic versus ≥2 antibiotics, respectively. Logistic and Cox proportional hazards regression assessed risk factors for HAIs and predictors of mortality, respectively.

RESULTS

Overall, 103 case and 195 control subjects were enrolled. An immunocompromised state (odds ratio [OR], 1.55; P = .047) and exposure to amikacin (OR, 13.81; P < .001), levofloxacin (OR, 2.05; P = .005), or trimethoprim-sulfamethoxazole (OR, 3.42; P = .009) were factors associated with XDR-GNB HAIs. Multiple factors in both case and control subjects significantly predicted increased mortality at different time intervals after HAI diagnosis. At 7 days, liver disease (hazard ratio [HR], 5.52), immunocompromised state (HR, 3.41), and bloodstream infection (HR, 2.55) predicted mortality; at 15 days, age (HR, 1.02 per year increase), liver disease (HR, 3.34), and immunocompromised state (HR, 2.03) predicted mortality; and, at 30 days, age (HR, 1.02 per 1-year increase), liver disease (HR, 3.34), immunocompromised state (HR, 2.03), and hospitalization in a medical ICU (HR, 1.85) predicted mortality.

CONCLUSION

HAIs caused by XDR-GNB were associated with potentially modifiable factors. Age, liver disease, and immunocompromised state, but not XDR-GNB HAIs, were associated with mortality.

Immune dysfunction prior to Staphylococcus aureus bacteremia is a determinant of long-term mortality

PURPOSE

The clinical implications for patients who survive serious infections are not well understood. It has been hypothesized that the excess mortality for survivors of sepsis observed in epidemiological studies is due to increased vulnerability to subsequent infections. We undertook this study to identify characteristics of patients who are at high risk for death after surviving a common type of blood-stream infection.

MATERIALS AND METHODS

At a single academic medical center, 237 patients with Staphylococcus aureus bacteremia admitted during a three-year period were retrospectively identified. The primary outcomes were 30-day and 31 to 90-day mortality after the first positive blood culture. The primary predictor variable of interest was clinical immune dysfunction prior to bacteremia.

RESULTS

The 30-day mortality was not significantly different for patients with and without prior immune dysfunction. However, during days 31 to 90, 11 patients (20%) with prior immune dysfunction compared to 10 patients (8.6%) without prior immune dysfunction died (OR 2.59, 95% CI 1.03-6.53, p = 0.04). In a Cox-proportional hazard model controlling for age, there was a significant association between prior immune dysfunction and greater 31 to 90 day mortality (HR 2.44, 95% CI 1.01-5.90, p = 0.05) and a non-significant trend towards occurrence of subsequent infections and greater 31 to 90 day mortality (HR 2.12, 95% CI 0.89-5.07, p = 0.09).

CONCLUSIONS

Patients with prior immune dysfunction are at high risk for death 31 to 90 days, but not <30 days, after S. aureus bacteremia. Further investigation is needed to determine if this finding is due to poor prognosis of chronic disease or increased vulnerability to subsequent infections.

Risk factors for urinary tract infection with multiple drug-resistant Escherichia coli in cats

The emergence of multiple drug-resistant (MDR) bacteria is a growing public health problem. The objective of this retrospective study was to identify risk factors associated with MDR Escherichia coli infection of the urinary tract in cats. All cats presenting with an E coli urinary infection between March 2010 and December 2012 were included and divided into two groups: an MDR group and a non-MDR group. The effects of different variables on the occurrence of an MDR E coli infection were evaluated: age, sex, additional diseases, number of antibiotics and number of days of hospitalisation. Fifty-two cats were identified (10 MDR and 42 non-MDR). The number of antibiotic groups used within the last 3 months was associated with an increased risk of MDR E coli urinary infection (P = 0.007). The association of the number of days of hospitalisation within the last 3 months and the increased risk of MDR E coli urinary infection did not reach significance (P = 0.090). This study provides evidence that systematic urinary culture with antibiotic sensitivity testing should be recommended when treating urinary tract infections if antibiotics have been prescribed within the past 3 months. Moreover, the selection of MDR bacteria through antibiotic use should be considered as a potential risk associated with treatment.

Risk factors for acquisition of multidrug-resistant Acinetobacter baumannii among cancer patients

BACKGROUND

Data regarding multidrug-resistant (MDR) Acinetobacter baumannii infections among cancer patients are limited.

METHODS

We conducted a case-control study to investigate the risk factors for acquisition of MDR A baumannii and the outcomes among cancer patients. Cases were inpatients with malignancy who had MDR A baumannii from any cultures between 2008 and 2011. Controls were inpatients with malignancy but no MDR A baumannii.

RESULTS

A total of 31 case patients were matched with 62 control patients. Hematologic malignancy (P = .036), need for dialysis (P = .01), admission for other reasons except elective surgery (P = .03), transfer from other health care facilities (P = .02), prolonged intensive care unit stay (P = .004), mechanical ventilation (P < .001), pressor use (P = .001), tube feeding (P < .001), transfusion (P = .009), and prior antimicrobial use (P < .001) were identified as significant risk factors in univariate analysis. Need for dialysis (odds ratio [OR], 18.23; P = .04) and prolonged intensive care unit stay (OR, 19.28; P = .01) remained significant in multivariate analysis. Lengths of stay were 28 days for the case patients and 10 days for the control patients (P = .001). The 90-day mortality rates were 41.9% and 29.0%, respectively (P = .20).

CONCLUSIONS

Acquisition of MDR A baumannii among cancer patients appears to be associated with general nosocomial infection risk factors rather than underlying malignancies.

Relationship between inhaled β₂-agonists and ventilator-associated pneumonia: a cohort study

OBJECTIVE

To determine the impact of aerosolized bronchodilators on ventilator-associated pneumonia.

DESIGN

Prospective cohort study.

SETTING

A 30-bed medical and surgical intensive care unit.

METHODS

All intubated patients requiring mechanical ventilation for >48 hrs were eligible during a 13-month period. Nebulized β2-agonists were administered at the intensive care unit physician's discretion. Ventilator-associated pneumonia definition included clinical and quantitative microbiological criteria. Only first ventilator-associated pneumonia episodes were analyzed. Risk factors for ventilator-associated pneumonia were determined using univariate and multivariate analyses. The influence of inhaled β2-agonists on ventilator-associated pneumonia occurrence was also adjusted for confounding factors using Cox's proportional-hazards model.

RESULTS

Ventilator-associated pneumonia was diagnosed in 137 (31%) of the 439 enrolled patients. Ventilator-associated pneumonia was early-onset in 14 (10%) patients. The incidence rate of ventilator-associated pneumonia was 20 per 1,000 ventilator days. Ventilator-associated pneumonia was polymicrobial in 16 (11%) patients, and related to multidrug-resistant bacteria in 42 (28%) patients. Most cases of ventilator-associated pneumonia were caused by Gram-negative bacteria. Inhaled β2-agonists were significantly more frequently used in patients with ventilator-associated pneumonia compared with those without ventilator-associated pneumonia (49% vs. 34%, odds ratio [95% confidence interval] = 1.9 [1.2-2.8], p = .003). Multivariate analysis identified aerosolized β2-agonists (odds ratio [95% confidence interval] = 1.7 [1.1-2.6], p = .012), Simplified Acute Physiology Score II at intensive care unit admission (odds ratio [95% confidence interval] = 1.01 [1.001-1.02] per point, p = .031), and red blood cell transfusion (odds ratio [95% confidence interval] = 2 [1.3-3.1], p = .001) as independent risk factors for ventilator-associated pneumonia. Cox's proportional-hazards model also identified inhaled β2-agonists as a risk factor for ventilator-associated pneumonia (odds ratio [95% confidence interval] = 1.52 [1.06-2.19], p = .021).

CONCLUSION

Use of aerosolized bronchodilators in intensive care unit mechanically ventilated patients is an independent risk factor for ventilator-associated pneumonia.

Acinetobacter baumannii infection in patients with hematologic malignancies in intensive care unit: risk factors and impact on mortality

PURPOSE

We investigated the characteristics of Acinetobacter baumannii infection in critically ill patients with hematologic malignancies.

MATERIALS AND METHODS

The prospectively collected data of patients with hematologic malignancies admitted to a medical intensive care unit of a university hospital from 2007 through 2010 were reviewed retrospectively.

RESULTS

One hundred twenty-eight patients were included in the study, among whom 35 (27%) developed 39 A baumannii infections. Pneumonia was the most common infection site of A baumannii. Presence of neutropenia, underlying hematologic malignancy, and the disease status did not affect the acquisition of the infection. Advancing age, prior exposure to aminoglycosides, central venous catheterization, and presence of nasogastric tube were the independent risk factors for the development of A baumannii infections. The mortality rate was higher in patients with A baumannii infections compared with the ones without (P = .009). However, in multivariate analysis, low Glasgow coma scale, prior immunosuppressive treatment, neutropenia, invasive mechanical ventilation, and severe sepsis were independently associated with mortality, whereas presence of A baumannii infection was not.

CONCLUSIONS

Despite the high mortality rate in critically ill patients with hematologic malignancies, presence of A baumannii infection was not an independent risk factor for mortality.

The impact of COPD on ICU mortality in patients with ventilator-associated pneumonia

OBJECTIVE

To determine the impact of COPD on intensive care unit (ICU) mortality in patients with VAP.

METHODS

This prospective observational study was performed in a mixed ICU during a 3-year period. Eligible patients received mechanical ventilation for >48 h and met criteria for microbiologically confirmed VAP. Risk factors for ICU mortality were determined using univariate and multivariable analyses.

RESULTS

Two hundred and fifteen patients with microbiologically confirmed VAP were included. Most VAP episodes were late-onset (88%), and Pseudomonas aeruginosa was the most frequently isolated bacterium (39% of VAP episodes). ICU mortality was significantly lower in non-COPD patients (n = 150) compared to COPD patients (n = 65) (43.3% vs 60%, p = 0.027, OR [95% CI] = 1.96 [1.8-3.54]). Duration (days) of mechanical ventilation and ICU stay median (IQR) in non-COPD patients were 25 (15-42) and 30 (18-48), whereas in COPD patients were 31 (19-45) and 36 (20-48) (p > 0.05). The differences in duration (days) of mechanical ventilation and ICU stay were significant between non-COPD patients and severe COPD (GOLD stage IV) patients (p = 0.001 and p = 0.02, respectively). Multivariable analysis identified COPD [OR (95% CI) 2.58 (1.337-5)], SAPS II [1.024 (1.006-1.024)] and presence of shock at VAP diagnosis [3.72 (1.88-7.39)] as independent risk factors for ICU mortality.

CONCLUSION

COPD, SAPS II, and shock at VAP diagnosis are independently associated with ICU mortality in patients who present VAP.

Risk of acquiring multidrug-resistant Gram-negative bacilli from prior room occupants in the intensive care unit

The objective of this prospective cohort study was to determine whether admission to an intensive care unit (ICU) room previously occupied by a patient with multidrug-resistant (MDR) Gram-negative bacilli (GNB) increases the risk of acquiring these bacteria by subsequent patients. All patients hospitalized for >48 h were eligible. Patients with MDR GNB at ICU admission were excluded. The MDR GNB were defined as MDR Pseudomonas aeruginosa, Acinetobacter baumannii and extended spectrum β-lactamase (ESBL) -producing GNB. All patients were hospitalized in single rooms. Cleaning of ICU rooms between two patients was performed using quaternary ammonium disinfectant. Risk factors for MDR P. aeruginosa, A. baumannii and ESBL-producing GNB were determined using univariate and multivariate analysis. Five hundred and eleven consecutive patients were included; ICU-acquired MDR P. aeruginosa was diagnosed in 82 (16%) patients, A. baumannii in 57 (11%) patients, and ESBL-producing GNB in 50 (9%) patients. Independent risk factors for ICU-acquired MDR P. aeruginosa were prior occupant with MDR P. aeruginosa (OR 2.3, 95% CI 1.2-4.3, p 0.012), surgery (OR 1.9, 95% CI 1.1-3.6, p 0.024), and prior piperacillin/tazobactam use (OR 1.2, 95% CI 1.1-1.3, p 0.040). Independent risk factors for ICU-acquired A. baumannii were prior occupant with A. baumannii (OR 4.2, 95% CI 2-8.8, p <0.001), and mechanical ventilation (OR 9.3, 95% CI 1.1-83, p 0.045). Independent risk factors for ICU-acquired ESBL-producing GNB were tracheostomy (OR 2.6, 95% CI 1.1-6.5, p 0.049), and sedation (OR 6.6, 95% CI 1.1-40, p 0.041). We conclude that admission to an ICU room previously occupied by a patient with MDR P. aeruginosa or A. baumannii is an independent risk factor for acquisition of these bacteria by subsequent room occupants. This relationship was not identified for ESBL-producing GNB.

Increased prevalence of and associated mortality with methicillin-resistant Staphylococcus aureus among hospitalized IBD patients

OBJECTIVES

Methicillin-resistant Staphylococcus aureus (MRSA) infection has become increasingly prevalent in US hospitals, and the impact of MRSA on hospitalized inflammatory bowel disease (IBD) patients is unknown.

METHODS

We used the Nationwide Inpatient Sample to identify admissions for IBD (n=116,842) between 1998 and 2004. We compared prevalence and in-hospital mortality of MRSA among IBD, non-IBD gastrointestinal (GI), and general medical inpatients.

RESULTS

MRSA prevalence increased from 4.5/10,000 to 19.0/10,000 over the 7-year period (P<0.0001). After adjustment for confounders, IBD inpatients were at increased risk of MRSA compared with the non-IBD GI (adjusted odds ratio (aOR) 1.61; 95% confidence interval (CI): 1.33-1.96) and general medical (aOR 1.36; 95% CI: 1.11-1.66) groups. Of those with MRSA, catheter-related infections were specifically more common among IBD compared with non-IBD GI and general inpatients (28.8% vs. 11.0% and 8.5%, respectively, P<0.0002). Bowel surgery, parenteral nutrition, and health insurance were predictors of MRSA infection, but the first two became insignificant after controlling for length of stay (LOS). Compared with LOS < or = 7 days, MRSA was more likely among those hospitalized 8-21 days (aOR 7.40; 95% CI: 4.68-11.7) and >21 days (aOR 58.6; 95% CI: 36.0-95.3). MRSA infection was associated with sevenfold increase in mortality (aOR 7.61; 95% CI: 3.33-17.4).

CONCLUSIONS

Hospitalized IBD patients are at increased risk of MRSA compared with non-IBD GI and general medical inpatients. Increased mortality in the IBD population associated with MRSA reinforces the importance of measures to prevent nosocomial infection and to reduce length of hospitalization.

Remifentanil discontinuation and subsequent intensive care unit-acquired infection: a cohort study

INTRODUCTION

Recent animal studies demonstrated immunosuppressive effects of opioid withdrawal resulting in a higher risk of infection. The aim of this study was to determine the impact of remifentanil discontinuation on intensive care unit (ICU)-acquired infection.

METHODS

This was a prospective observational cohort study performed in a 30-bed medical and surgical university ICU, during a one-year period. All patients hospitalised in the ICU for more than 48 hours were eligible. Sedation was based on a written protocol including remifentanil with or without midazolam. Ramsay score was used to evaluate consciousness. The bedside nurse adjusted sedative infusion to obtain the target Ramsay score. Univariate and multivariate analyses were performed to determine risk factors for ICU-acquired infection.

RESULTS

Five hundred and eighty-seven consecutive patients were included in the study. A microbiologically confirmed ICU-acquired infection was diagnosed in 233 (39%) patients. Incidence rate of ICU-acquired infection was 38 per 1000 ICU-days. Ventilator-associated pneumonia was the most frequently diagnosed ICU-acquired infection (23% of study patients). Pseudomonas aeruginosa was the most frequently isolated microorganism (30%). Multivariate analysis identified remifentanil discontinuation (odds ratio (OR) = 2.53, 95% confidence interval (CI) = 1.28 to 4.99, P = 0.007), simplified acute physiology score II at ICU admission (1.01 per point, 95% CI = 1 to 1.03, P = 0.011), mechanical ventilation (4.49, 95% CI = 1.52 to 13.2, P = 0.006), tracheostomy (2.25, 95% CI = 1.13 to 4.48, P = 0.021), central venous catheter (2.9, 95% CI = 1.08 to 7.74, P = 0.033) and length of hospital stay (1.05 per day, 95% CI = 1.03 to 1.08, P < 0.001) as independent risk factors for ICU-acquired infection.

CONCLUSIONS

Remifentanil discontinuation is independently associated with ICU-acquired infection.

[Systematic screening for methicillin-resistant Staphylococcus aureus (MRSA) in the nasal cavities of patients hospitalized in the dermatology departments of the Saint-Louis Hospital]

OBJECTIVES

In a bid to combat methicillin-resistant Staphylococcus aureus (MRSA) more efficiently in our department, we performed a study to 1) clarify the MRSA carriage rate in patients hospitalized in the department; 2) evaluate the rate of MRSA acquisition during hospitalization; 3) describe the MRSA carrier profile; 4) study the morbidity and mortality associated with MRSA.

PATIENTS AND METHODS

We conducted a three-month prospective study in all patients hospitalized for more than 24hours in the dermatology department of the Saint-Louis Hospital. Nasal swab cultures were performed on the day of admission, once a week thereafter and on the day of discharge. Clinical and epidemiological data were individually reviewed by means of a standardized questionnaire.

RESULTS

In 310 patients, the prevalence of nasal MRSA carriage at admission was 6.5%. During hospitalization, 1.9% of our patients became colonized with MRSA. MRSA carriers were significantly older than non-carriers and had been hospitalized more frequently over the previous 12 months, principally in intensive care or in intermediate or long-term care facilities, and erosive and/or ulcerated dermatitis was more common in this population. Of the 27 patients colonized with MRSA, only three had MRSA infections, and these were successfully treated with antibiotics.

DISCUSSION

The observed rate of MRSA carriage was close to that seen in intensive care units (7%). While systematic screening for MRSA in patients with erosive and/or ulcerated dermatitis would allow detection of twice as many cases of MRSA than the usual screening recommendations, this would be associated with little tangible benefit and high costs, and we therefore decided not to change the usual MRSA screening politic in our dermatology department.

Antimicrobial treatment for ventilator-associated tracheobronchitis: a randomized, controlled, multicenter study

Introduction

Ventilator-associated tracheobronchitis (VAT) is associated with increased duration of mechanical ventilation. We hypothesized that, in patients with VAT, antibiotic treatment would be associated with reduced duration of mechanical ventilation.

Methods

We conducted a prospective, randomized, controlled, unblinded, multicenter study. Patients were randomly assigned (1:1) to receive or not receive intravenous antibiotics for 8 days. Patients with ventilator-associated pneumonia (VAP) prior to VAT and those with severe immunosuppression were not eligible. The trial was stopped early because a planned interim analysis found a significant difference in intensive care unit (ICU) mortality.

Results

Fifty-eight patients were randomly assigned. Patient characteristics were similar in the antibiotic (n = 22) and no antibiotic (n = 36) groups. Pseudomonas aeruginosa was identified in 32% of VAT episodes. Although no difference was found in mechanical ventilation duration and length of ICU stay, mechanical ventilation-free days were significantly higher (median [interquartile range], 12 [8 to 24] versus 2 [0 to 6] days, P < 0.001) in the antibiotic group than in the no antibiotic group. In addition, subsequent VAP (13% versus 47%, P = 0.011, odds ratio [OR] 0.17, 95% confidence interval [CI] 0.04 to 0.70) and ICU mortality (18% versus 47%, P = 0.047, OR 0.24, 95% CI 0.07 to 0.88) rates were significantly lower in the antibiotic group than in the no antibiotic group. Similar results were found after exclusion of patients with do-not-resuscitate orders and those randomly assigned to the no antibiotic group but who received antibiotics for infections other than VAT or subsequent VAP.

Conclusion

In patients with VAT, antimicrobial treatment is associated with a greater number of days free of mechanical ventilation and lower rates of VAP and ICU mortality. However, antibiotic treatment has no significant impact on total duration of mechanical ventilation.

Trial registration

ClinicalTrials.gov, number NCT00122057.

Stenotrophomonas maltophilia: changing spectrum of a serious bacterial pathogen in patients with cancer

Stenotrophomonas maltophilia colonization/infection in patients with cancer has significantly increased over the past 2 decades. Patients with prolonged neutropenia, exposure to broad-spectrum antibiotics, and those requiring mechanical ventilation have higher risk of infection. These micro-organisms are intrinsically resistant to carbapenems, and exposure to these agents has been linked to selection of S. maltophilia. Recently, these infections are being documented in patients without traditional risk factors. The spectrum of infection includes bacteremia, catheter-related infection, pneumonia, complicated biliary and urinary tract infection, and skin and skin-structure infection. Trimethoprim-sulfamethoxazole is the therapeutic agent of choice, but resistance is increasingly being reported. Susceptibility to alternative agents is unpredictable. Combination therapy and alternative routes of drug administration, such as aerosolized aminoglycoside, might be necessary. New insights into the mechanisms of drug resistance might lead to identification of new target sites. Agents that improve outer-membrane permeability and broad-spectrum beta-lactamase inhibitors may favorably impact difficult-to-treat (i.e., multidrug resistant) S. maltophilia infections.

Hospital Pharmacy Pulse - Recent Publications on Medications and Pharmacy

Hospital Pharmacy presents this feature to keep pharmacists abreast of new publications in the medical/pharmacy literature. Articles of interest will be abstracted monthly regarding a broad scope of topics. Suggestions or comments may be addressed to: Jacyntha Sterling, Drug Information Specialist at Saint Francis Hospital, 6161 S Yale Ave., Tulsa, OK 74136 or e-mail: jasterling@saintfrancis.com .