Increasing the Reliability of Fully Automated Surveillance for Central Line-Associated Bloodstream Infections.

OBJECTIVE: To increase reliability of the algorithm used in our fully automated electronic surveillance system by adding rules to better identify bloodstream infections secondary to other hospital-acquired infections. METHODS: Intensive care unit (ICU) patients with positive blood cultures were reviewed. Central line-associated bloodstream infection (CLABSI) determinations were based on 2 sources: routine surveillance by infection preventionists, and fully automated surveillance. Discrepancies between the 2 sources were evaluated to determine root causes. Secondary infection sites were identified in most discrepant cases. New rules to identify secondary sites were added to the algorithm and applied to this ICU population and a non-ICU population. Sensitivity, specificity, predictive values, and kappa were calculated for the new models. RESULTS: Of 643 positive ICU blood cultures reviewed, 68 (10.6%) were identified as central line-associated bloodstream infections by fully automated electronic surveillance, whereas 38 (5.9%) were confirmed by routine surveillance. New rules were tested to identify organisms as central line-associated bloodstream infections if they did not meet one, or a combination of, the following: (I) matching organisms (by genus and species) cultured from any other site; (II) any organisms cultured from sterile site; (III) any organisms cultured from skin/wound; (IV) any organisms cultured from respiratory tract. The best-fit model included new rules I and II when applied to positive blood cultures in an ICU population. However, they didn't improve performance of the algorithm when applied to positive blood cultures in a non-ICU population. CONCLUSION: Electronic surveillance system algorithms may need adjustment for specific populations.

Multicenter evaluation of computer automated versus traditional surveillance of hospital-acquired bloodstream infections.

OBJECTIVE: Central line-associated bloodstream infection (BSI) rates are a key quality metric for comparing hospital quality and safety. Traditional BSI surveillance may be limited by interrater variability. We assessed whether a computer-automated method of central line-associated BSI detection can improve the validity of surveillance. DESIGN: Retrospective cohort study. SETTING: Eight medical and surgical intensive care units (ICUs) in 4 academic medical centers. METHODS: Traditional surveillance (by hospital staff) and computer algorithm surveillance were each compared against a retrospective audit review using a random sample of blood culture episodes during the period 2004-2007 from which an organism was recovered. Episode-level agreement with audit review was measured with κ statistics, and differences were assessed using the test of equal κ coefficients. Linear regression was used to assess the relationship between surveillance performance (κ) and surveillance-reported BSI rates (BSIs per 1,000 central line-days). RESULTS: We evaluated 664 blood culture episodes. Agreement with audit review was significantly lower for traditional surveillance (κ [95% confidence interval (CI) = 0.44 [0.37-0.51]) than computer algorithm surveillance (κ [95% CI] = 0.58; P = .001). Agreement between traditional surveillance and audit review was heterogeneous across ICUs (P = .01); furthermore, traditional surveillance performed worse among ICUs reporting lower (better) BSI rates (P = .001). In contrast, computer algorithm performance was consistent across ICUs and across the range of computer-reported central line-associated BSI rates. Conclusions: Compared with traditional surveillance of bloodstream infections, computer automated surveillance improves accuracy and reliability, making interfacility performance comparisons more valid.

Development, Implementation and Use of Electronic Surveillance for Ventilator-Associated Events (VAE) in Adults.

Mechanical ventilation provides an important, life-saving therapy for severely ill patients, but ventilated patients are at an increased risk for complications, poor outcomes, and death during hospitalization.1 The timely measurement of negative outcomes is important in order to identify potential issues and to minimize the risk to patients. The Centers for Disease Control and Prevention (CDC) created an algorithm for identifying Ventilator-Associated Events (VAE) in adult patients for reporting to the National Healthcare Safety Network (NHSN). Currently, the primarily manual surveillance tools require a significant amount of time from hospital infection prevention (IP) staff to apply and interpret. This paper describes the implementation of an electronic VAE tool using an internal clinical data repository and an internally developed electronic surveillance system that resulted in a reduction of labor efforts involved in identifying VAE at Barnes Jewish Hospital (BJH).

Fluid balance and cardiac function in septic shock as predictors of hospital mortality.

INTRODUCTION: Septic shock is a major cause of morbidity and mortality throughout the world. Unfortunately, the optimal fluid management of septic shock is unknown and currently is empirical. METHODS: A retrospective analysis was performed at Barnes-Jewish Hospital (St. Louis, Missouri). Consecutive patients (n = 325) hospitalized with septic shock who had echocardiographic examinations performed within 24 hours of shock onset were enrolled. RESULTS: A total of 163 (50.2%) patients with septic shock died during hospitalization. Non-survivors had a significantly larger positive net fluid balance within the 24 hour window of septic shock onset (median (IQR): 4,374 ml (1,637 ml, 7,260 ml) vs. 2,959 ml (1,639.5 ml, 4,769.5 ml), P = 0.004). The greatest quartile of positive net fluid balance at 24 hours and eight days post-shock onset respectively were found to predict hospital mortality, and the greatest quartile of positive net fluid balance at eight days post-shock onset was an independent predictor of hospital mortality (adjusted odds ratio (AOR), 1.66; 95% CI, 1.39 to 1.98; P = 0.004). Survivors were significantly more likely to have mild left ventricular dysfunction as evaluated by bedside echocardiography and non-survivors had slightly elevated left ventricular ejection fraction, which was also found to be an independent predictor of outcome. CONCLUSIONS: Our data confirms the importance of fluid balance and cardiac function as outcome predictors in patients with septic shock. A clinical trial to determine the optimal administration of intravenous fluids to patients with septic shock is needed.

Clostridium difficile infection: a multicenter study of epidemiology and outcomes in mechanically ventilated patients.

OBJECTIVES: Clostridium difficile is a leading cause of hospital-associated infection in the United States. The purpose of this study is to assess the prevalence of C. difficile infection among mechanically ventilated patients within the ICUs of three academic hospitals and secondarily describe the influence of C. difficile infection on the outcomes of these patients. DESIGN: A retrospective cohort study. SETTING: ICUs at three teaching hospitals: Barnes-Jewish Hospital, Mayo Clinic, and Creighton University Medical Center over a 2-year period. PATIENTS: All hospitalized patients requiring mechanical ventilation for greater than 48 hours within an ICU were eligible for inclusion. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 5,852 consecutive patients admitted to the ICU were included. Three hundred eighty-six (6.6%) patients with development of C. difficile infection while in the hospital (5.39 cases/1,000 patient days). Septic shock complicating C. difficile infection occurred in 34.7% of patients. Compared with patients without C. difficile infection (n = 5,466), patients with C. difficile infection had a similar hospital mortality rate (25.1% vs 26.3%, p = 0.638). Patients with C. difficile infection were significantly more likely to be discharged to a skilled nursing or rehabilitation facility (42.4% vs 31.9%, p < 0.001), and the median hospital (23 d vs 15 d, p < 0.001) and ICU length of stay (12 d vs 8 d, p < 0.001) were found to be significantly longer in patients with C. difficile infection. CONCLUSIONS: Clostridium difficile infection is a relatively common nosocomial infection in mechanically ventilated patients and is associated with prolonged length of hospital and ICU stay, and increased need for skilled nursing care or rehabilitation following hospital discharge.

Catheter removal versus retention in the management of catheter-associated enterococcal bloodstream infections.

BACKGROUND: Enterococci are an important cause of central venous catheter (CVC)-associated bloodstream infections (CA-BSI). It is unclear whether CVC removal is necessary to successfully manage enterococcal CA-BSI. METHODS: A 12-month retrospective cohort study of adults with enterococcal CA-BSI was conducted at a tertiary care hospital; clinical, microbiological and outcome data were collected. RESULTS: A total of 111 patients had an enterococcal CA-BSI. The median age was 58.2 years (range 21 to 94 years). There were 45 (40.5%) infections caused by Entercoccus faecalis (among which 10 [22%] were vancomycin resistant), 61 (55%) by Enterococcus faecium (57 [93%] vancomycin resistant) and five (4.5%) by other Enterococcus species. Patients were treated with linezolid (n=51 [46%]), vancomycin (n=37 [33%]), daptomycin (n=11 [10%]), ampicillin (n=2 [2%]) or quinupristin/dalfopristin (n=2 [2%]); seven (n=6%) patients did not receive adequate enterococcal treatment. Additionally, 24 (22%) patients received adjunctive gentamicin treatment. The CVC was retained in 29 (26.1%) patients. Patients with removed CVCs showed lower rates of in-hospital mortality (15 [18.3%] versus 11 [37.9]; P=0.03), but similar rates of recurrent bacteremia (nine [11.0%] versus two (7.0%); P=0.7) and a similar post-BSI length of hospital stay (median days [range]) (11.1 [1.7 to 63.1 days] versus 9.3 [1.9 to 31.8 days]; P=0.3). Catheter retention was an independent predictor of mortality (OR 3.34 [95% CI 1.21 to 9.26]). CONCLUSIONS: To the authors' knowledge, the present article describes the largest enterococcal CA-BSI series to date. Mortality was increased among patients who had their catheter retained. Additional prospective studies are necessary to determine the optimal management of enterococcal CA-BSI.

HISTORIQUE: Les entérocoques constituent une cause importante de bactériémies liées à un cathéter veineux central (CVC). On ne sait pas s'il est nécessaire de retirer le CVC pour réussir la prise en charge de ce type de bactériémie. MÉTHODOLOGIE: Les auteurs ont mené une étude rétrospective de cohorte de 12 mois auprès d'adultes ayant une bactériémie liée à un CVC dans un hôpital de soins tertiaires. Ils ont colligé des données cliniques, des données microbiologiques et des données d'issue. RÉSULTATS: Au total, 111 patients étaient atteints d'une bactériémie à entérocoque liée à un CVC. Ils avaient un âge médian de 58,2 ans (plage de 21 à 94 ans). Les chercheurs ont constaté 45 infections (40,5 %) causées par l'Enterococcus faecalis (dont 10 [22 %] résistantes à la vancomycine), 61 infections (55 %) causées par l'Enterococcus faecium (dont 57 [93 %] résistantes à la vancomycine) et cinq (4,5 %) causées par d'autres espèces d'Enterococcus. Les patients ont été traités au linézolide (n=51 [46 %]), à la vancomycine (n=37 [33 %]), à la daptomycine (n=11 [10 %]), à l'ampicilline (n=2 [2 %]) ou à la quinupristine-dalfopristine (n=2 [2 %]). Sept patients (n=6 %) n'ont pas reçu de traitement convenable contre les entérocoques. De plus, 24 patients (22%) ont reçu un traitement d'appoint à la gentamicine. Vingt-neuf patients (26,1 %) ont conservé leur CVC. Les patients à qui on l'avait retiré présentaient des taux de mortalité hospitalière plus faibles (15 [18,3 %] par rapport à 11 [37,9]; P=0,03), mais des taux similaires de bactériémie récurrente (neuf [11,0 %] par rapport à deux (7,0 %); P=0,7) et une durée d'hospitalisation similaire après la bactériémie (jours médians [plage]) (11,1 [1,7 à 63,1 jours] par rapport à 9,3 [1,9 à 31,8 jours]; P=0,3). Le maintien du cathéter était un prédicteur indépendant de mortalité (RRR 3,34 [95 % IC 1,21 à 9,26]). CONCLUSIONS: En autant que le sache les auteurs, le présent article décrit la plus grosse série de bactériémies liées à un CVC. La mortalité était plus élevée chez les patients qui conservaient leur cathéter. D'autres études prospectives s'imposent pour déterminer la prise en charge optimale de la bactériémie à entérocoque liée à un CVC.

Septic shock attributed to Candida infection: importance of empiric therapy and source control.

BACKGROUND: Delayed treatment of candidemia has previously been shown to be an important determinant of patient outcome. However, septic shock attributed to Candida infection and its determinants of outcome have not been previously evaluated in a large patient population. METHODS: A retrospective cohort study of hospitalized patients with septic shock and blood cultures positive for Candida species was conducted at Barnes-Jewish Hospital, a 1250-bed urban teaching hospital (January 2002-December 2010). RESULTS: Two hundred twenty-four consecutive patients with septic shock and a positive blood culture for Candida species were identified. Death during hospitalization occurred among 155 (63.5%) patients. The hospital mortality rate for patients having adequate source control and antifungal therapy administered within 24 hours of the onset of shock was 52.8% (n = 142), compared to a mortality rate of 97.6% (n = 82) in patients who did not have these goals attained (P < .001). Multivariate logistic regression analysis demonstrated that delayed antifungal treatment (adjusted odds ratio [AOR], 33.75; 95% confidence interval [CI], 9.65-118.04; P = .005) and failure to achieve timely source control (AOR, 77.40; 95% CI, 21.52-278.38; P = .001) were independently associated with a greater risk of hospital mortality. CONCLUSIONS: The risk of death is exceptionally high among patients with septic shock attributed to Candida infection. Efforts aimed at timely source control and antifungal treatment are likely to be associated with improved clinical outcomes.

Electronic surveillance for healthcare-associated central line-associated bloodstream infections outside the intensive care unit.

BACKGROUND: Manual surveillance for central line-associated bloodstream infections (CLABSIs) by infection prevention practitioners is time-consuming and often limited to intensive care units (ICUs). An automated surveillance system using existing databases with patient-level variables and microbiology data was investigated. METHODS: Patients with a positive blood culture in 4 non-ICU wards at Barnes-Jewish Hospital between July 1, 2005, and December 31, 2006, were evaluated. CLABSI determination for these patients was made via 2 sources; a manual chart review and an automated review from electronically available data. Agreement between these 2 sources was used to develop the best-fit electronic algorithm that used a set of rules to identify a CLABSI. Sensitivity, specificity, predictive values, and Pearson's correlation were calculated for the various rule sets, using manual chart review as the reference standard. RESULTS: During the study period, 391 positive blood cultures from 331 patients were evaluated. Eighty-five (22%) of these were confirmed to be CLABSI by manual chart review. The best-fit model included presence of a catheter, blood culture positive for known pathogen or blood culture with a common skin contaminant confirmed by a second positive culture and the presence of fever, and no positive cultures with the same organism from another sterile site. The best-performing rule set had an overall sensitivity of 95.2%, specificity of 97.5%, positive predictive value of 90%, and negative predictive value of 99.2% compared with intensive manual surveillance. CONCLUSIONS: Although CLABSIs were slightly overpredicted by electronic surveillance compared with manual chart review, the method offers the possibility of performing acceptably good surveillance in areas where resources do not allow for traditional manual surveillance.

Institutional perspective on the impact of positive blood cultures on the economic and clinical outcomes of patients with complicated skin and skin structure infections: focus on gram-positive infections.

BACKGROUND: Traditionally, skin and skin structure infections (SSSIs) have been viewed as having a lower risk of mortality, morbidity, and cost compared with other types of infection. The influence of secondary bacteremia on the medicoeconomic outcomes of patients with SSSIs has not been well described. OBJECTIVE: The goal of this study was to evaluate the impact of bacteremia complicating SSSIs on length of hospital stay and costs. METHODS: This was a retrospective cohort study involving 579 patients with culture-positive SSSIs who were admitted to Barnes-Jewish Hospital, a major academic medical center, between April 1, 2005, and December 31, 2007. The outcomes evaluated in this analysis included hospital mortality, length of stay, hospital costs, and hospital readmission. RESULTS: Secondary bacteremia was present in 277 (47.8%) patients. Hospital mortality was statistically greater among patients with bacteremia (7.9% vs 1.0%; P < 0.001). The unadjusted median length of stay in bacteremic patients was 7.1 days compared with 2.8 days in those without bacteremia (P < 0.001 by log-rank test). This finding correlated with total hospital costs, which were greater in patients with bacteremia (median values: $14,623 vs $5841.50; P < 0.001). In a Cox model controlling for multiple confounders, bacteremia independently correlated with hospital duration (adjusted hazard ratio [HR], 1.820; 95% CI, 1.654-2.003; P < 0.001) and hospital costs (adjusted HR, 1.895; 95% CI, 1.723-2.083; P < 0.001). Hospital readmission within 30 days of discharge was also significantly more common among patients with SSSIs complicated by bacteremia (24.5% vs 12.9%; P < 0.001). CONCLUSIONS: Bacteremia complicating SSSIs occurred in almost 50% of patients infected with gram-positive bacteria in our institution. Beyond its impact on mortality, bacteremia is associated with increased length of stay, hospital costs, and readmission. However, these data are from a single academic medical center and may not be adjusted for all applicable confounders.

Resistance to empiric antimicrobial treatment predicts outcome in severe sepsis associated with Gram-negative bacteremia.

BACKGROUND: Gram-negative bacteria are an important cause of severe sepsis. Recent studies have demonstrated reduced susceptibility of Gram-negative bacteria to currently available antimicrobial agents. METHODS: We performed a retrospective cohort study of patients with severe sepsis who were bacteremic with Pseudomonas aeruginosa, Acinetobacter species, or Enterobacteriaceae from 2002 to 2007. Patients were identified by the hospital informatics database and pertinent clinical data (demographics, baseline severity of illness, source of bacteremia, and therapy) were retrieved from electronic medical records. All patients were treated with antimicrobial agents within 12 hours of having blood cultures drawn that were subsequently positive for bacterial pathogens. The primary outcome was hospital mortality. RESULTS: A total of 535 patients with severe sepsis and Gram-negative bacteremia were identified. Hospital mortality was 43.6%, and 82 (15.3%) patients were treated with an antimicrobial regimen to which the causative pathogen was resistant. Patients infected with a resistant pathogen had significantly greater risk of hospital mortality (63.4% vs 40.0%; P < 0.001). In a multivariate analysis, infection with a pathogen that was resistant to the empiric antibiotic regimen, increasing APACHE II scores, infection with Pseudomonas aeruginosa, healthcare-associated hospital-onset infection, mechanical ventilation, and use of vasopressors were independently associated with hospital mortality. CONCLUSIONS: In severe sepsis attributed to Gram-negative bacteremia, initial treatment with an antibiotic regimen to which the causative pathogen is resistant was associated with increased hospital mortality. This finding suggests that rapid determination of bacterial susceptibility could influence treatment choices in patients with severe sepsis potentially improving their clinical outcomes.

Inappropriate antibiotic therapy in Gram-negative sepsis increases hospital length of stay.

OBJECTIVES: To describe the impact of initially inappropriate antibiotic therapy on hospital length of stay in Gram-negative severe sepsis and septic shock. DESIGN: Retrospective cohort. SETTING: Academic urban hospital. PATIENTS: Patients with Gram-negative bacteremia (primary or secondary, nosocomial or non-nosocomial) and severe sepsis or septic shock. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We defined initially inappropriate antibiotic therapy as occurring when the patient either was not administered an antibiotic within 24 hrs of sepsis onset or was treated with an antibiotic to which the culprit pathogen was resistant in vitro. The cohort included 760 subjects (mean age 59.3 ± 16.3 yrs, mean Acute Physiology and Chronic Health Evaluation II score 23.7 ± 6.7). More than half of infections were nosocomial (55.1%), and Escherichia coli represented the most common pathogen (n = 225). Pseudomonas species were isolated in 17.4% of patients. Nearly one-third of patients (31.3%) received initially inappropriate antibiotic therapy. Patients administered initially inappropriate antibiotic therapy were more likely to have a nosocomial infection, to have underlying cancer or diabetes or both, to require chronic hemodialysis, and to undergo mechanical ventilation. Those administered initially inappropriate antibiotic therapy also faced higher inhospital mortality. The unadjusted median length of stay after sepsis onset in those administered initially inappropriate antibiotic therapy was 11 days compared to 9 days in those treated appropriately (p = .028 by log-rank test). In a Cox model controlling for the multiple confounders noted, initially inappropriate antibiotic therapy independently correlated with continued hospitalization (adjusted hazard ratio 1.19, 95% confidence interval 1.01-1.40, p = .044). Adjusting for these covariates indicated that initially inappropriate antibiotic therapy independently increased the median attributable length of stay by 2 days. CONCLUSIONS: Initially inappropriate antibiotic therapy occurs in one-third of persons with severe sepsis and septic shock attributable to Gram-negative organisms. Beyond its impact on mortality, initially inappropriate antibiotic therapy is significantly associated with length of stay in this population. Efforts to decrease rates of initially inappropriate antibiotic therapy may serve to improve hospital resource use by leading to shorter overall hospital stays.

Quality of traditional surveillance for public reporting of nosocomial bloodstream infection rates.

CONTEXT: Central line-associated bloodstream infection (BSI) rates, determined by infection preventionists using the Centers for Disease Control and Prevention (CDC) surveillance definitions, are increasingly published to compare the quality of patient care delivered by hospitals. However, such comparisons are valid only if surveillance is performed consistently across institutions. OBJECTIVE: To assess institutional variation in performance of traditional central line-associated BSI surveillance. DESIGN, SETTING, AND PARTICIPANTS: We performed a retrospective cohort study of 20 intensive care units among 4 medical centers (2004-2007). Unit-specific central line-associated BSI rates were calculated for 12-month periods. Infection preventionists, blinded to study participation, performed routine prospective surveillance using CDC definitions. A computer algorithm reference standard was applied retrospectively using criteria that adapted the same CDC surveillance definitions. MAIN OUTCOME MEASURES: Correlation of central line-associated BSI rates as determined by infection preventionist vs the computer algorithm reference standard. Variation in performance was assessed by testing for institution-dependent heterogeneity in a linear regression model. RESULTS: Forty-one unit-periods among 20 intensive care units were analyzed, representing 241,518 patient-days and 165,963 central line-days. The median infection preventionist and computer algorithm central line-associated BSI rates were 3.3 (interquartile range [IQR], 2.0-4.5) and 9.0 (IQR, 6.3-11.3) infections per 1000 central line-days, respectively. Overall correlation between computer algorithm and infection preventionist rates was weak (ρ = 0.34), and when stratified by medical center, point estimates for institution-specific correlations ranged widely: medical center A: 0.83; 95% confidence interval (CI), 0.05 to 0.98; P = .04; medical center B: 0.76; 95% CI, 0.32 to 0.93; P = .003; medical center C: 0.50, 95% CI, -0.11 to 0.83; P = .10; and medical center D: 0.10; 95% CI -0.53 to 0.66; P = .77. Regression modeling demonstrated significant heterogeneity among medical centers in the relationship between computer algorithm and expected infection preventionist rates (P < .001). The medical center that had the lowest rate by traditional surveillance (2.4 infections per 1000 central line-days) had the highest rate by computer algorithm (12.6 infections per 1000 central line-days). CONCLUSIONS: Institutional variability of infection preventionist rates relative to a computer algorithm reference standard suggests that there is significant variation in the application of standard central line-associated BSI surveillance definitions across medical centers. Variation in central line-associated BSI surveillance practice may complicate interinstitutional comparisons of publicly reported central line-associated BSI rates.

Hospitalizations with healthcare-associated complicated skin and skin structure infections: impact of inappropriate empiric therapy on outcomes.

OBJECTIVE: Inappropriate empiric therapy worsens outcomes in certain healthcare-associated infections (HCAI). We studied the association of inappropriate empiric therapy with outcomes in patients with HCA complicated skin and skin structure infections (cSSSI). DESIGN: A single-center retrospective cohort study. PATIENTS: Hospitalized with a culture-positive cSSSI. MEASUREMENTS: We defined HCA-cSSSI as having ≥1 of these risk factors: (1) recent hospitalization, (2) recent antibiotics, (3) hemodialysis, (4) transfer from a nursing home, and inappropriate treatment as no antimicrobial therapy active against the pathogen(s) within 24 hours of obtaining culture specimen. We performed descriptive and multivariate statistics to compute the impact of inappropriate empiric therapy on outcomes. Hospital length of stay (LOS) served as primary and mortality as secondary outcomes. RESULTS: Of the 717 patients with culture-positive cSSSI, 527 (73.5%) had HCAI, of whom 405 (76.9%) received appropriate treatment. A higher proportion of those receiving inappropriate than appropriate treatment had a decubitus ulcer (29.5% vs. 10.9%, P < 0.001), a device-associated infection (42.6% vs. 28.6%, P = 0.004), or bacteremia (68.9% vs. 57.8%, P = 0.028). The frequency of methicillin-resistant Staphylococcus aureus (MRSA) did not differ between the groups. The low overall unadjusted mortality rate did not vary based on initial treatment. In a multivariable analysis adjusting for potential confounders inappropriate therapy had an attributable increase in hospital LOS of 1.8 days (95% CI, 1.4-2.3). CONCLUSION: Similar to other populations with HCAI, HCA-cSSSI patients are likely to receive inappropriate empiric therapy for their infection. This early exposure is associated with a significant prolongation of the hospitalization by nearly 2 days.

Methicillin-resistant Staphylococcus aureus nasal colonization is a poor predictor of intensive care unit-acquired methicillin-resistant Staphylococcus aureus infections requiring antibiotic treatment.

OBJECTIVE: To test whether intensive care unit (ICU) nasal screening for methicillin-resistant Staphylococcus aureus (MRSA) predicts the presence or absence of MRSA infections requiring antimicrobial treatment. DESIGN: A prospective cohort study. SETTING: Medical ICU at Barnes-Jewish Hospital, a 1252-bed urban teaching hospital. PATIENTS: Seven hundred forty-nine consecutive patients admitted to the medical ICU over a 7-mo period (November 2007 through June 2008). INTERVENTIONS: Nasal swabs were obtained at ICU admission and weekly thereafter for MRSA detection by using polymerase chain reaction. All subjects were followed for the development of MRSA infection during their ICU stay. MEASUREMENTS AND MAIN RESULTS: One hundred sixty-four (21.9%) patients had positive nasal colonization with MRSA at the time of ICU admission. The predictive accuracy of MRSA nasal colonization for ICU-acquired MRSA infections, either lower respiratory tract infection or bloodstream infection, was poor (lower respiratory tract infection: sensitivity, 24.2%; specificity, 78.5%; positive predictive value, 17.7%; and negative predictive value, 84.4%; and bloodstream infection: sensitivity, 23.1%; specificity, 78.2%; positive predictive value, 11.0%; and negative predictive value, 89.7%). Addition of nasal-colonization results obtained during the ICU stay did not appreciably change the predictive accuracy of this test for identification of subsequent lower respiratory tract infections and bloodstream infections attributed to MRSA requiring antimicrobial treatment. CONCLUSIONS: In this analysis, nasal colonization with MRSA was found to be a poor predictor for the subsequent occurrence of MRSA lower respiratory tract infections and MRSA bloodstream infections requiring antimicrobial treatment. Clinicians should be cautious in using the results of nasal-colonization testing to determine the need for MRSA treatment among patients with ICU-acquired infections.

Bacteremia increases the risk of death among patients with soft-tissue infections.

BACKGROUND: Soft-tissue infections traditionally have been viewed as carrying a lower risk of death than other types of infection such as pneumonia, blood stream, and intra-abdominal. The influence of secondary bacteremia on the outcomes of patients with soft-tissue infections is not well described. OBJECTIVES: To describe the risk factors for bacteremia among patients admitted to an urban medical center with soft-tissue infections and the influence of bacteremia on outcomes. METHODS: A retrospective cohort study of 717 patients with culture-positive non-necrotizing soft-tissue infections admitted between April 1, 2005, and December 31, 2007. RESULTS: Bacteremia was present in 52% of the patients. Increasing age, previous hospitalization, decubitus or lower-extremity ulcers, device-related soft-tissue infection, and polymicrobial infection were independent predictors of bacteremia. Intensive care unit admission (adjusted odds ratio [AOR] 3.57; 95% confidence interval [CI] 2.17, 5.86), lower-extremity ulcer (AOR 3.43; 95% CI 2.07, 5.70), and bacteremia (AOR 6.37; 95% CI 3.34, 12.12) were independent predictors of in-hospital death. When patients with device-related soft-tissue infections were excluded, the rate of secondary bacteremia was 37.6% (201/535), and it remained an independent predictor of in-hospital death. CONCLUSIONS: The occurrence of bacteremia in soft-tissue infections is associated with a greater risk of death. Health care providers should be aware of the risk factors for bacteremia in patients with soft-tissue infections in order to provide more appropriate initial antimicrobial therapy and to ascertain its presence as a prognostic indicator.

Empiric combination antibiotic therapy is associated with improved outcome against sepsis due to Gram-negative bacteria: a retrospective analysis.

The optimal approach for empirical antibiotic therapy in patients with severe sepsis and septic shock remains controversial. A retrospective cohort study was conducted in the intensive care units of a university hospital. The data from 760 patients with severe sepsis or septic shock associated with Gram-negative bacteremia was analyzed. Among this cohort, 238 (31.3%) patients received inappropriate initial antimicrobial therapy (IIAT). The hospital mortality rate was statistically greater among patients receiving IIAT compared to those initially treated with an appropriate antibiotic regimen (51.7% versus 36.4%; P < 0.001). Patients treated with an empirical combination antibiotic regimen directed against Gram-negative bacteria (i.e., beta-lactam plus aminoglycoside or fluoroquinolone) were less likely to receive IIAT compared to monotherapy (22.2% versus 36.0%; P < 0.001). The addition of an aminoglycoside to a carbapenem would have increased appropriate initial therapy from 89.7 to 94.2%. Similarly, the addition of an aminoglycoside would have increased the appropriate initial therapy for cefepime (83.4 to 89.9%) and piperacillin-tazobactam (79.6 to 91.4%). Logistic regression analysis identified IIAT (adjusted odds ratio [AOR], 2.30; 95% confidence interval [CI] = 1.89 to 2.80) and increasing Apache II scores (1-point increments) (AOR, 1.11; 95% CI = 1.09 to 1.13) as independent predictors for hospital mortality. In conclusion, combination empirical antimicrobial therapy directed against Gram-negative bacteria was associated with greater initial appropriate therapy compared to monotherapy in patients with severe sepsis and septic shock. Our experience suggests that aminoglycosides offer broader coverage than fluoroquinolones as combination agents for patients with this serious infection.

Formulation of a model for automating infection surveillance: algorithmic detection of central-line associated bloodstream infection.

OBJECTIVE: To formulate a model for translating manual infection control surveillance methods to automated, algorithmic approaches. DESIGN: We propose a model for creating electronic surveillance algorithms by translating existing manual surveillance practices into automated electronic methods. Our model suggests that three dimensions of expert knowledge be consulted: clinical, surveillance, and informatics. Once collected, knowledge should be applied through a process of conceptualization, synthesis, programming, and testing. RESULTS: We applied our framework to central vascular catheter associated bloodstream infection surveillance, a major healthcare performance outcome measure. We found that despite major barriers such as differences in availability of structured data, in types of databases used and in semantic representation of clinical terms, bloodstream infection detection algorithms could be deployed at four very diverse medical centers. CONCLUSIONS: We present a framework that translates existing practice-manual infection detection-to an automated process for surveillance. Our experience details barriers and solutions discovered during development of electronic surveillance for central vascular catheter associated bloodstream infections at four hospitals in a variety of data environments. Moving electronic surveillance to the next level-availability at a majority of acute care hospitals nationwide-would be hastened by the incorporation of necessary data elements, vocabularies and standards into commercially available electronic health records.

Early prediction of septic shock in hospitalized patients.

BACKGROUND: Hospitalized patients who develop severe sepsis have significant morbidity and mortality. Early goal-directed therapy has been shown to decrease mortality in severe sepsis and septic shock, though a delay in recognizing impending sepsis often precludes this intervention. OBJECTIVE: To identify early predictors of septic shock among hospitalized non-intensive care unit (ICU) medical patients. DESIGN: Retrospective cohort analysis. SETTING: A 1200-bed academic medical center. PATIENTS: Derivation cohort consisted of 13,785 patients hospitalized during 2005. The validation cohorts consisted of 13,737 patients during 2006 and 13,937 patients from 2007. INTERVENTION: Development and prospective validation of a prediction model using Recursive Partitioning And Regression Tree (RPART) analysis. METHODS: RPART analysis of routine laboratory and hemodynamic variables from the derivation cohort to identify predictors prior to the occurrence of shock. Two models were generated, 1 including arterial blood gas (ABG) data and 1 without. RESULTS: When applied to the 2006 cohort, 347 (54.7%) and 121 (19.1%) of the 635 patients developing septic shock were correctly identified by the 2 models, respectively. For the 2007 patients, the 2 models correctly identified 367 (55.0%) and 102 (15.3%) of the 667 patients developing septic shock, respectively. CONCLUSIONS: Readily available data can be employed to predict non-ICU patients who develop septic shock several hours prior to ICU admission.

Epidemiology and outcomes of hospitalizations with complicated skin and skin-structure infections: implications of healthcare-associated infection risk factors.

OBJECTIVE: Healthcare-associated infections are likely to be caused by drug-resistant and possibly mixed organisms and to be treated with inappropriate antibiotics. Because prompt appropriate treatment is associated with better outcomes, we studied the epidemiology of healthcare-associated complicated skin and skin-structure infections (cSSSIs). PATIENTS: Persons hospitalized with cSSSI and a positive culture result. METHODS: We conducted a single-center retrospective cohort study from April 2006 through December 2007. We differentiated healthcare-associated from community-acquired cSSSIs by at least 1 of the following risk factors: (1) recent hospitalization, (2) recent antibiotics, (3) hemodialysis, and (4) transfer from a nursing home. Inappropriate treatment was defined as no antimicrobial therapy with activity against the offending pathogen(s) within 24 hours after collection of a culture specimen. Mixed infections were those caused by both a gram-positive and a gram-negative organism. RESULTS: Among 717 hospitalized patients with cSSSI, 527 (73.5%) had healthcare-associated cSSSI. Gram-negative organisms were more common (relative risk, 1.24 [95% confidence interval, 1.14-1.35) and inappropriate treatment trended toward being more common (odds ratio, 1.29 [95% confidence interval, 0.85-1.95]) in healthcare-associated cSSSI than in community-acquired cSSSI. Mixed cSSSIs occurred in 10.6% of patients with healthcare-associated cSSSI and 6.3% of those with community-acquired cSSSI (P = .082) and were more likely to be treated inappropriately than to be nonmixed infections (odds ratio, 2.42 [95% confidence interval, 1.43-4.10]). Both median length of hospital stay (6.2 vs 2.9 days; P < .001) and mortality rate (6.6% vs 1.1%; P = .003) were significantly higher for healthcare-associated cSSSI than community-acquired cSSSI. CONCLUSIONS: Healthcare-associated cSSSIs are common and are likely to be caused by gram-negative organisms. Mixed infections carry a >2-fold greater risk of inappropriate treatment. Healthcare-associated cSSSIs are associated with increased mortality and prolonged length of hospital stay, compared with community-acquired cSSSIs.

Clostridium difficile-associated disease and mortality among the elderly critically ill.

OBJECTIVE: : To describe the epidemiology of and to develop a simple 30-day mortality clinical decision rule among critically ill patients > or =65 yrs. Increasing incidence of hospitalizations with and emergence of hypervirulent epidemic strains have made Clostridium difficile-associated disease an important public health concern. Advanced age is a risk factor for development of and death from Clostridium difficile-associated disease. Intensive care unit patients with Clostridium difficile-associated disease have a high mortality, but neither the burden of nor risk factors for death among the elderly intensive care unit patients with Clostridium difficile-associated disease are well understood. DESIGN: : Secondary analysis of a retrospective cohort study. SETTING: : All intensive care units at a single academic institution. PATIENTS: : A total of 278 critically ill patients with Clostridium difficile-associated disease; n = 148 aged > or =65 yrs. INTERVENTIONS: : None in addition to routine intensive care unit care. MEASUREMENTS AND MAIN RESULTS: : Univariate analyses were performed to compare characteristics and outcomes of the elderly vs. the younger groups, and elderly 30-day survivors with nonsurvivors. Multivariable logistic regression model was developed with 30-day mortality as a dependent variable. Covariates retained in the model were assigned weighted points to develop a 30-day mortality prediction score. Area under the receiver operating characteristics curve and cross-validation analyses evaluated the score characteristics. Elderly patients were 68% more likely to experience 30-day mortality than the younger group. Absence of chronic respiratory disease (R), age 75+ yrs (A), septic shock (S), and Acute Physiology and Chronic Health Evaluation II score 20+ (A) comprised the RASA score, whose receiver operating characteristics was 0.740; 95% Confidence Interval was 0.663-0.817. CONCLUSIONS: : Elderly patients represent approximately 50% of intensive care unit patients with Clostridium difficile-associated disease and have a higher 30-day mortality than younger patients. A simple prediction rule incorporating determinants of 30-day mortality easily available at the bedside may aid in optimizing treatment decisions in this growing population.