Empiric antibiotic therapy for Staphylococcus aureus bacteremia may not reduce in-hospital mortality: a retrospective cohort study

Mortality patterns in patients with Staphylococcus aureus bacteremia during the COVID-19 pandemic: Predictors and insights

Objectives

This paper aims to determine the Staphylococcus aureus bacteremia (SAB) in-hospital mortality rate and its associated risk factors during the COVID-19 pandemic.

Methods

A total of 167 SAB samples were collected between March 2020 and March 2022 at a teaching hospital in Tehran, Iran. The patient's baseline data and antibiograms were collected. The outcome of the study was in-hospital mortality.

Results

The overall in-hospital mortality rate was 41.9 %, with higher mortality observed in patients over 60 years old (P = 0.032), those with community-acquired Staphylococcus aureus bacteremia (P = 0.010), and those admitted to the ICU (P = 0.016). Antibiotic resistance profiles indicated a higher mortality in resistant S.aureus strains but only significant for ciprofloxacin (P = 0.001), methicillin (P = 0.047), and sulfamethoxazole (P = 0.023). Multivariate analysis identified age, sex, ICU admission, and the source of bacteremia as independent predictors of mortality, while COVID-19 coinfection and resistance to antibiotics were not found to be significant predictors.

Conclusion

SAB remains a challenging infection that is amplified by the pandemic. Older age and ICU admission are significant mortality predictors. In settings with a high prevalence of MRSA, factors like age, sex, and quality of care outweigh pathogen-related factors such as antibiotic resistance.

Effects of Inappropriate Administration of Empirical Antibiotics on Mortality in Adults With Bacteraemia: Systematic Review and Meta-Analysis

Introduction

Bloodstream infections are associated with high mortality rates and contribute substantially to healthcare costs, but a consensus on the prognostic benefits of appropriate empirical antimicrobial therapy (EAT) for bacteraemia is lacking.

Methods

We performed a systematic search of the PubMed, Cochrane Library, and Embase databases through July 2021. Studies comparing the mortality rates of patients receiving appropriate and inappropriate EAT were considered eligible. The quality of the included studies was assessed using Joanna Briggs Institute checklists.

Results

We ultimately assessed 198 studies of 89,962 total patients. The pooled odds ratio (OR) for the prognostic impacts of inappropriate EAT was 2.06 (P < 0.001), and the funnel plot was symmetrically distributed. Among subgroups without between-study heterogeneity (I² = 0%), those of patients with severe sepsis and septic shock (OR, 2.14), Pitt bacteraemia scores of ≥4 (OR, 1.88), cirrhosis (OR, 2.56), older age (OR, 1.78), and community-onset/acquired Enterobacteriaceae bacteraemia infection (OR, 2.53) indicated a significant effect of inappropriate EAT on mortality. The pooled adjusted OR of 125 studies using multivariable analyses for the effects of inappropriate EAT on mortality was 2.02 (P < 0.001), and the subgroups with low heterogeneity (I² < 25%) exhibiting significant effects of inappropriate EAT were those of patients with vascular catheter infections (adjusted OR, 2.40), pneumonia (adjusted OR, 2.72), or Enterobacteriaceae bacteraemia (adjusted OR, 4.35). Notably, the pooled univariable and multivariable analyses were consistent in revealing the negligible impacts of inappropriate EAT on the subgroups of patients with urinary tract infections and Enterobacter bacteraemia.

Conclusion

Although the current evidence is insufficient to demonstrate the benefits of prompt EAT in specific bacteraemic populations, we indicated that inappropriate EAT is associated with unfavorable mortality outcomes overall and in numerous subgroups. Prospective studies designed to test these specific populations are needed to ensure reliable conclusions.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021270274.

A Systematic Review of the Effect of Delayed Appropriate Antibiotic Treatment on the Outcomes of Patients With Severe Bacterial Infections

BACKGROUND

Patients with severe bacterial infections often experience delay in receiving appropriate treatment. Consolidated evidence of the impact of delayed appropriate treatment is needed to guide treatment and improve outcomes.

RESEARCH QUESTION

What is the impact of delayed appropriate antibacterial therapy on clinical outcomes in patients with severe bacterial infections?

STUDY DESIGN AND METHODS

Literature searches of MEDLINE and Embase, conducted on July 24, 2018, identified studies published after 2007 reporting the impact of delayed appropriate therapy on clinical outcomes for hospitalized adult patients with bacterial infections. Where appropriate, results were pooled and analyzed with delayed therapy modeled three ways: delay vs no delay in receiving appropriate therapy; duration of delay; and inappropriate vs appropriate initial therapy. This article reports meta-analyses on the effect of delay and duration of delay.

RESULTS

The eligibility criteria were met by 145 studies, of which 37 contributed data to analyses of effect of delay. Mortality was significantly lower in patients receiving appropriate therapy without delay compared with those experiencing delay (OR, 0.57; 95% CI, 0.45-0.72). Mortality was also lower in the no-delay group compared with the delay group in subgroups of studies reporting mortality at 20 to 30 days, during ICU stay, or in patients with bacteremia (OR, 0.57 [95% CI, 0.43-0.76]; OR, 0.47 [95% CI, 0.27-0.80]; and OR, 0.54 [95% CI, 0.40-0.75], respectively). No difference was found in time to appropriate therapy between those who died and those who survived (P = .09), but heterogeneity between studies was high.

INTERPRETATION

Avoiding delayed appropriate therapy is essential to reduce mortality in patients with severe bacterial infections.

CLINICAL TRIAL REGISTRATION

PROSPERO; No.: CRD42018104669; URL: www.crd.york.ac.uk/prospero/.

Antibiotic Resistance and the Risk of Recurrent Bacteremia

Background

Direct health effects of antibiotic resistance are difficult to assess. We quantified the risk of recurrent bacteremia associated with resistance.

Methods

We extracted antimicrobial susceptibility testing data on blood isolates from the Dutch surveillance system for antimicrobial resistance between 2008 and 2017. First and first recurrent (4–30 days) bacteremia episodes were categorized as susceptible, single nonsusceptible, or co-nonsusceptible to third-generation cephalosporins without or with carbapenems (Enterobacteriaceae), ceftazidime without or with carbapenems (Pseudomonas species), aminopenicillins without or with vancomycin (Enterococcus species), or as methicillin-sensitive/-resistant S. aureus (MSSA/MRSA). We calculated risks of recurrent bacteremia after nonsusceptible vs susceptible first bacteremia, estimated the crude population attributable effect of resistance for the Netherlands, and calculated risks of nonsusceptible recurrent bacteremia after a susceptible first episode.

Results

Risk ratios for recurrent bacteremia after a single- and co-nonsusceptible first episode, respectively, vs susceptible first episode, were 1.7 (95% confidence interval [CI], 1.5–2.0) and 5.2 (95% CI, 2.1–12.4) for Enterobacteriaceae, 1.3 (95% CI, 0.5–3.1) and 5.0 (95% CI, 2.9–8.5) for Pseudomonas species, 1.4 (95% CI, 1.2–1.7) and 1.6 (95% CI, 0.6–4.2) for Enterococcus species, and 1.6 (95% CI, 1.1–2.4) for MRSA vs MSSA. The estimated population annual number of recurrent bacteremias associated with nonsusceptibility was 40. The risk of nonsusceptible recurrent bacteremia after a susceptible first episode was at most 0.4% (Pseudomonas species).

Conclusions

Although antibiotic nonsusceptibility was consistently associated with higher risks of recurrent bacteremia, the estimated annual number of additional recurrent episodes in the Netherlands (40) was rather limited.

[Current status of antibiotic therapy for Staphylococcus aureus sepsis in children]

OBJECTIVE

To investigate the current status of empirical antibiotic therapy for children with Staphylococcus aureus sepsis and the effect of therapeutic paradigm on prognosis based on a retrospective analysis.

METHODS

A total of 78 children with Staphylococcus aureus sepsis who were admitted from January 2014 to August 2017 were enrolled. According to the preferred empirical antibiotics before the detection of Staphylococcus aureus by blood culture, these children were divided into a carbapenem group with 16 children, a β-lactam group with 37 children, a vancomycin group with 15 children and a vancomycin+β-lactam group with 10 children. A retrospective analysis was performed for related clinical data including general status, underlying diseases, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, history of use of immunosuppressant, drug resistance to methicillin and prognosis. A logistic regression analysis was used to investigate the effect of empirical antibiotic therapy on the clinical outcome and prognosis of children with Staphylococcus aureus sepsis.

RESULTS

There were no significant differences among these groups in general status, underlying diseases, history of use of immunosuppressant, APACHE II score, nosocomial infection and detection rate of methicillin-resistant Staphylococcus aureus (P>0.05). There were significant differences in the incidence rate of septic shock and in-hospital mortality among these four groups (P<0.05). The carbapenem group had the highest incidence rate of septic shock and in-hospital mortality (69% and 50% respectively). The multivariate logistic regression analysis showed that empirical antibiotic therapy with different antibiotics had different risks for septic shock and in-hospital death in children with Staphylococcus aureus sepsis (P<0.05), and that an APACHE II score of ≥15 was an independent risk factor for septic shock in these children (P<0.05). The carbapenem group had significantly higher risks of septic shock and in-hospital death than the vancomycin group (P<0.05).

CONCLUSIONS

Inappropriate empirical use of antibiotics may lead to a poor prognosis in children with Staphylococcus aureus sepsis. Empirical use of carbapenems is not recommended for children suspected of Staphylococcus aureus sepsis.

[Current status of antibiotic therapy for Staphylococcus aureus sepsis in children]

OBJECTIVE

To investigate the current status of empirical antibiotic therapy for children with Staphylococcus aureus sepsis and the effect of therapeutic paradigm on prognosis based on a retrospective analysis.

METHODS

A total of 78 children with Staphylococcus aureus sepsis who were admitted from January 2014 to August 2017 were enrolled. According to the preferred empirical antibiotics before the detection of Staphylococcus aureus by blood culture, these children were divided into a carbapenem group with 16 children, a β-lactam group with 37 children, a vancomycin group with 15 children and a vancomycin+β-lactam group with 10 children. A retrospective analysis was performed for related clinical data including general status, underlying diseases, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, history of use of immunosuppressant, drug resistance to methicillin and prognosis. A logistic regression analysis was used to investigate the effect of empirical antibiotic therapy on the clinical outcome and prognosis of children with Staphylococcus aureus sepsis.

RESULTS

There were no significant differences among these groups in general status, underlying diseases, history of use of immunosuppressant, APACHE II score, nosocomial infection and detection rate of methicillin-resistant Staphylococcus aureus (P>0.05). There were significant differences in the incidence rate of septic shock and in-hospital mortality among these four groups (P<0.05). The carbapenem group had the highest incidence rate of septic shock and in-hospital mortality (69% and 50% respectively). The multivariate logistic regression analysis showed that empirical antibiotic therapy with different antibiotics had different risks for septic shock and in-hospital death in children with Staphylococcus aureus sepsis (P<0.05), and that an APACHE II score of ≥15 was an independent risk factor for septic shock in these children (P<0.05). The carbapenem group had significantly higher risks of septic shock and in-hospital death than the vancomycin group (P<0.05).

CONCLUSIONS

Inappropriate empirical use of antibiotics may lead to a poor prognosis in children with Staphylococcus aureus sepsis. Empirical use of carbapenems is not recommended for children suspected of Staphylococcus aureus sepsis.

New paradigm for rapid achievement of appropriate therapy in special populations: coupling antibiotic dose optimization rapid microbiological methods

INTRODUCTION

Some special patient populations (e.g. critically ill, burns, hematological malignancy, post-major surgery, post-major trauma) have characteristics that lead to higher rates of failure and mortality associated with infection. Choice of effective antibiotics and optimized doses are challenging in these patients that are commonly infected by multidrug-resistant pathogens. Areas covered: A review of the importance of diagnosis and the place of newer microbiological methods (e.g. whole-genome sequencing) to ensure rapid transition from empiric to directed antibiotic therapy is provided. The effects of pathophysiological changes on antibiotic pharmacokinetics are also provided. Expert opinion: Product information dosing regimens do not address the pharmacokinetic alterations that can occur in special patient populations and increase the likelihood of therapeutic failure and the emergence of bacterial resistance. Altered dosing approaches, supplemented with the use of dosing software and therapeutic drug monitoring, may be needed to ensure optimal antibiotic exposure and better therapeutic outcomes in these patients with severe infection. Dose optimization needs to be coupled with advanced microbiological techniques that enable rapid microbiological identification and characterization of resistance mechanism to ensure that maximally effective directed therapy can be chosen.

Risk factors for the appearance of secondary foci of infection in children with community-acquired Staphylococcus aureus bacteraemia. Cohort study 2010-2016

INTRODUCTION

Community-acquired Staphylococcus aureus (SA) bacteraemia is a common cause of hospitalisation in children. The occurrence of secondary foci (SF) of SA infection is associated with higher morbidity and mortality.

OBJECTIVES

To identify risk factors for SF of infection in children with community-acquired SA bacteraemia.

MATERIAL AND METHODS

Prospective cohort. All children aged from 30 days to 16 years admitted to a paediatric referral hospital between January 2010 and December 2016 for community-acquired infections, with SA isolated in blood cultures, were included. Microbiological, demographic and clinical characteristics were compared, with or without SF infection after 72hours of hospitalisation.

RESULTS

A total of 283 patients were included, 65% male (n=184), with a median age of 60 months (IQR: 30-132). Seventeen per cent (n=48) had at least one underlying disease and 97% (n=275) had some clinical focus of infection, the most common being: osteoarticular 55% (n=156) and soft tissue abscesses 27% (n=79). A total of 65% (n=185) were resistant to methicillin. A SF of infection was found in 16% of patients (n=44). The SF identified were pneumonia 73% (n=32), osteoarticular 11% (n=5), soft tissue 11% (n=5) and central nervous system 5% (n=2). In the multivariate analysis, the persistence of positive blood cultures after the fifth day (OR: 2.40, 95%CI: 1.07-5.37, P<0.001) and sepsis (OR: 17.23, 95%CI 5.21-56.9, P<0.001) were predictors of SF. There was no association with methicillin sensitivity.

CONCLUSIONS

In this cohort, methicillin-resistant SA infections predominated. The occurrence of SF of infection was associated with the persistence of bacteraemia after the fifth day and sepsis on admission.

Reduced Vancomycin Susceptibility of Methicillin-Susceptible Staphylococcus aureus Has No Significant Impact on Mortality but Results in an Increase in Complicated Infection

Methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infections (BSIs) often lead to severe complications despite the availability of effective antibiotics. It remains unclear whether elevated vancomycin MICs are associated with worse outcomes. We conducted a 2-year retrospective cohort study (n = 252) of patients with MSSA BSIs at a tertiary care hospital. We defined reduced vancomycin susceptibility (RVS) as a Microscan MIC of 2 mg/liter. All strains were genotyped (spa) and assessed for agr functionality. Multivariable logistic regression models were used to examine the impact of RVS phenotype and strain genotype on 30-day all-cause mortality and complicated bacteremia (metastatic spread, endovascular infection, or duration ≥3 days). One-third of patients (84/252) were infected with RVS isolates. RVS Infections were more frequently associated with metastatic or embolic sites of infection (36% versus 17%, P < 0.001), and endovascular infection (26% versus 12%, P = 0.004). These infections occurred more often in patients with fewer underlying comorbidities (Charlson comorbidity index of ≥3 [73% versus 88%, P = 0.002]). Genotyping identified 127 spa-types and 14 Spa-clonal complexes (Spa-CCs). Spa-CC002 and Spa-CC008 were more likely to exhibit the RVS phenotype versus other Spa-CCs (OR = 2.2, P < 0.01). The RVS phenotype was not significantly associated with 30-day mortality; however, it was associated with complicated bacteremia (adjusted odds ratio of 2.35 [range, 1.26 to 4.37]; P = 0.007) in adjusted analyses. The association of RVS strains with complicated infection and fewer underlying comorbidities suggests the phenotype as a potential marker of strain virulence in MSSA BSIs. The RVS phenotype itself was not a significant predictor of mortality in this patient cohort. Further studies are necessary to explore this host-pathogen relationship.

The Use of Bloodstream Infection Mortality to Measure the Impact of Antimicrobial Stewardship Interventions: Assessing the Evidence

This review sets out to evaluate the current evidence on the impact of inappropriate therapy on bloodstream infections (BSI) and associated mortality. Based on the premise that better prescribing practices should result in better patient outcomes, BSI mortality may be a useful metric to evaluate antimicrobial stewardship (AMS) interventions. A systematic search was performed in key medical databases to identify papers published in English between 2005 and 2015 that examined the association between inappropriate prescribing and BSI mortality in adult patients. Only studies that included BSIs caused by ESKAPE (Enterococcus faecium/faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter species) organisms were included. Study quality was assessed using the GRADE criteria and results combined using a narrative synthesis. We included 46 studies. Inappropriate prescribing was associated with an overall increase in mortality in BSI. In BSI caused by resistant gram positive organisms, such as methicillin resistant S. aureus, inappropriate therapy resulted in up to a 3-fold increase in mortality. In BSI caused by gram negative (GN) resistant organisms a much greater impact ranging from 3 to 25 fold increase in the risk of mortality was observed. While the overall quality of the studies is limited by design and the variation in the definition of appropriate prescribing, there appears to be some evidence to suggest that inappropriate prescribing leads to increased mortality in patients due to GN BSI. The highest impact of inappropriate prescribing was seen in patients with GN BSI, which may be a useful metric to monitor the impact of AMS interventions.

Impact of appropriate empirical antibiotic treatment on recurrence and mortality in patients with bacteraemia: a population-based cohort study

Background

Data on the impact of empirical antibiotic treatment (EAT) on patient outcome in a population-based setting are sparse. We assessed the association between EAT and the risk of recurrence within one year, short-term- (2–30 days) and long-term (31–365 days) mortality in a Danish cohort of bacteraemia patients.

Methods

A cohort study including all patients hospitalized with incident bacteraemia during 2007–2008 in the Copenhagen City and County areas and the North Denmark Region. EAT was defined as the antibiotic treatment given at the 1^st notification of a positive blood culture. The definition of recurrence took account of pathogen species, site of infection, and time frame and was not restricted to homologous pathogens. The vital status was determined through the civil registration system. Association estimates between EAT and the outcomes were estimated by Cox and logistic regression models.

Results

In 6483 eligible patients, 712 (11%) had a recurrent episode. A total of 3778 (58%) patients received appropriate EAT, 1290 (20%) received inappropriate EAT, while EAT status was unrecorded for 1415 (22%) patients. The 2–30 day mortality was 15.1%, 17.4% and 19.2% in patients receiving appropriate EAT, inappropriate EAT, and unknown EAT, respectively. Among patients alive on day 30, the 31–365 day mortality was 22.3% in patients given appropriate EAT compared to 30.7% in those given inappropriate EAT. Inappropriate EAT was independently associated with recurrence (HR 1.25; 95% CI = 1.03–1.52) and long-term mortality (OR 1.35; 95% CI = 1.10–1.60), but not with short-term mortality (OR 0.85; 95% CI = 0.70–1.02) after bacteraemia.

Conclusions

Our data indicate that appropriate EAT is associated with reduced incidence of recurrence and lower long-term mortality following bacteraemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2233-z) contains supplementary material, which is available to authorized users.

Factors associated with 12 week case-fatality in Staphylococcus aureus bacteraemia: a prospective cohort study

Staphylococcus aureus bacteraemia (SAB) is a frequent and deadly disease. Given the lack of a randomized trial, optimal first-line antibiotic treatment is still debated. Our aim was to identify prognostic factors in SAB patients and to analyse the impact of first-line antibiotics. The VIRSTA prospective cohort study was conducted in eight tertiary care centres in France. Consecutive incident adults in whom a blood culture drawn in participating centres grew S. aureus between April 2009 and October 2011 were prospectively followed for 12 weeks. Factors associated with 12-week case-fatality were identified by multivariate logistic regression. We enrolled 2091 patients and analysed survival in 1972 (median age 67.8 years, interquartile range 55.5-78.9; females 692/1972, 35.1%). SAB was nosocomial or healthcare-related in 1372/1972 (69.6%) of cases and the primary focus was unknown in 414/1972 (21.0%) of cases. Week 12 case-fatality rate was 671/1972 (34.0%). The main independent prognostic factors on multivariate analysis were age (adjusted OR by 10-year increment 1.56; 95% CI 1.44-1.69), septic shock (OR 5.11; 95% CI 3.84-6.80), metastatic cancer (OR 4.28; 95% CI 2.88-6.38), and unknown primary focus (OR 2.62; 95% CI 2.02-3.41). In the 1538 patients with methicillin-sensitive S. aureus (MSSA) bacteraemia, first-line empiric antistaphylococcal penicillins (OR 0.40; 95% CI 0.17-0.95) and vancomycin (OR 0.37; 95% CI 0.17-0.83), alone or combined with an aminoglycoside, were associated with better outcome compared with other antibiotics. There are few modifiable prognostic factors for SAB. Initiating empiric antibiotics with antistaphylococcal penicillins or vancomycin may be associated with better outcome in MSSA bacteraemia.

Effects of inappropriate empirical antibiotic therapy on mortality in patients with healthcare-associated methicillin-resistant Staphylococcus aureus bacteremia: a propensity-matched analysis

Background

The purported value of empirical therapy to cover methicillin-resistant Staphylococcus aureus (MRSA) has been debated for decades. The purpose of this study was to evaluate the effects of inappropriate empirical antibiotic therapy on clinical outcomes in patients with healthcare-associated MRSA bacteremia (HA-MRSAB).

Methods

A prospective, multicenter, observational study was conducted in 15 teaching hospitals in the Republic of Korea from February 2010 to July 2011. The study subjects included adult patients with HA-MRSAB. Covariate adjustment using the propensity score was performed to control for bias in treatment assignment. The predictors of in-hospital mortality were determined by multivariate logistic regression analyses.

Results

In total, 345 patients with HA-MRSAB were analyzed. The overall in-hospital mortality rate was 33.0 %. Appropriate empirical antibiotic therapy was given to 154 (44.6 %) patients. The vancomycin minimum inhibitory concentrations of the MRSA isolates ranged from 0.5 to 2 mg/L by E-test. There was no significant difference in mortality between propensity-matched patient pairs receiving inappropriate or appropriate empirical antibiotics (odds ratio [OR] = 1.20; 95 % confidence interval [CI] = 0.71–2.03). Among patients with severe sepsis or septic shock, there was no significant difference in mortality between the treatment groups. In multivariate analyses, severe sepsis or septic shock (OR = 5.45; 95 % CI = 2.14–13.87), Charlson’s comorbidity index (per 1-point increment; OR = 1.52; 95 % CI = 1.27–1.83), and prior receipt of glycopeptides (OR = 3.24; 95 % CI = 1.08–9.67) were independent risk factors for mortality.

Conclusion

Inappropriate empirical antibiotic therapy was not associated with clinical outcome in patients with HA-MRSAB. Prudent use of empirical glycopeptide therapy should be justified even in hospitals with high MRSA prevalence.

Effects of vancomycin versus nafcillin in enhancing killing of methicillin-susceptible Staphylococcus aureus causing bacteremia by human cathelicidin LL-37

Recent studies have demonstrated that anti-staphylococcal beta-lactam antibiotics, like nafcillin, render methicillin-resistant Staphylococcus aureus (MRSA) more susceptible to killing by innate host defense peptides (HDPs), such as cathelicidin LL-37. We compared the effects of growth in 1/4 minimum inhibitory concentration (MIC) of nafcillin or vancomycin on the LL-37 killing of 92 methicillin-susceptible S. aureus (MSSA) isolates. For three randomly selected strains among these, we examined the effects of nafcillin, vancomycin, daptomycin, or linezolid on LL-37 killing and autolysis. Growth in the presence of subinhibitory nafcillin significantly enhanced LL-37 killing of MSSA compared to vancomycin and antibiotic-free controls. Nafcillin also reduced MSSA production of the golden staphylococcal pigment staphyloxanthin in 39 % of pigmented strains vs. 14 % for vancomycin. Among the antibiotics tested, only nafcillin resulted in significantly increased MSSA autolysis. These studies point to additional mechanisms of anti-staphylococcal activity of nafcillin beyond direct bactericidal activity, properties that vancomycin and other antibiotic classes do not exhibit. The ability of nafcillin to enhance sensitivity to innate HDPs may contribute to its superior effectiveness against MSSA, as suggested by studies comparing clinical outcomes to vancomycin treatment.

Comparison of outcomes in patients with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia who are treated with β-lactam vs vancomycin empiric therapy: a retrospective cohort study

BACKGROUND

Prior studies suggested that vancomycin may be inferior to β-lactams for the empiric treatment of methicillin-susceptible S. aureus (MSSA) bacteremia. We assessed whether empiric therapy with β-lactams compared to vancomycin was associated with differences in clinical outcomes in patients with MSSA bacteremia.

METHODS

We conducted a retrospective cohort study of adult inpatients with their first episode of MSSA bacteremia at two tertiary care hospitals in Vancouver, Canada, between 2007 and 2014. Exposure was either empiric β-lactam or vancomycin therapy. All patients received definitive treatment with cloxacillin or cefazolin. The primary outcome was 28-day mortality. Secondary outcomes were 90-day mortality, recurrent infection at 6 months, duration of bacteremia and hospital length-of-stay. Outcomes were adjusted using multivariable logistic regression.

RESULTS

Of 814 patients identified, 400 met inclusion criteria (β-lactam = 200, vancomycin = 200). Overall 28-day mortality was 8.5 % (n=34). There were more cases of infective endocarditis in the β-lactam than in the vancomycin group [45 (22.5 %) vs 23 (11.5 %), p < 0.01]. Adjusted mortality at 28 days was similar between the two groups (OR: 1.14; 95 % CI: 0.49-2.64). No differences in secondary outcomes were observed. Transition to cloxacillin or cefazolin occurred within a median of 67.8 h in the vancomycin group.

CONCLUSIONS

Empiric therapy with β-lactams was not associated with differences in all-cause mortality, recurrent infection, microbiological cure or hospital length-of-stay compared to vancomycin. Vancomycin monotherapy may be appropriate for the empiric treatment of MSSA bacteremia if definitive therapy with cloxacillin or cefazolin can be initiated within 3 days.

Comparative effectiveness of β-lactam versus vancomycin empiric therapy in patients with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia

BACKGROUND

Vancomycin may be inferior to β-lactams for the empiric treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia. We compared empiric β-lactams to vancomycin to assess clinical outcomes in patients with MSSA bacteremia.

METHODS

We conducted a retrospective cohort study of adult inpatients with their first episode of MSSA bacteremia at two tertiary care hospitals in Vancouver, Canada, between 2007 and 2014. Exposure was either empiric β-lactam with or without vancomycin or vancomycin monotherapy. All patients received definitive treatment with cloxacillin or cefazolin. The primary outcome was 28-day mortality. Secondary outcomes were 90-day mortality, duration of bacteremia, and hospital length-of-stay. Outcomes were adjusted using multivariable logistic regression.

RESULTS

Of 669 patients identified, 255 met inclusion criteria (β-lactam = 131, vancomycin = 124). Overall 28-day mortality was 7.06 % (n = 18). There were more cases of infective endocarditis in the β-lactam than in the vancomycin group [24 (18.3 %) vs 12 (9.7 %), p = 0.05]. Adjusted mortality at 28 days was similar between the two groups (OR 0.85; 95 % CI 0.27-2.67). The duration of bacteremia was longer in the vancomycin group (97.1 vs 70.7 h, p = 0.007). Transition to cloxacillin or cefazolin occurred within a median of 68.3 h in the vancomycin group.

CONCLUSIONS

Empiric β-lactams was associated with earlier clearance of bacteremia by a median of 1 day compared to vancomycin. Future prospective studies are needed to confirm our findings.

Determinants of Outcome in Hospitalized Patients With Methicillin-Resistant Staphylococcus aureus Bloodstream Infection: Results From National Surveillance in Canada, 2008-2012

BACKGROUND Bloodstream infection (BSI) due to methicillin-resistant Staphylococcus aureus (MRSA) is associated with considerable morbidity and mortality. OBJECTIVE To determine the incidence of MRSA BSI in Canadian hospitals and to identify variables associated with increased mortality. METHODS Prospective surveillance for MRSA BSI conducted in 53 Canadian hospitals from January 1, 2008, through December 31, 2012. Thirty-day all-cause mortality was determined, and logistic regression analysis was used to identify variables associated with mortality. RESULTS A total of 1,753 patients with MRSA BSI were identified (incidence, 0.45 per 1,000 admissions). The most common sites presumed to be the source of infection were skin/soft tissue (26.6%) and an intravascular catheter (22.0%). The most common spa types causing MRSA BSI were t002 (USA100/800; 55%) and t008 (USA300; 29%). Thirty-day all-cause mortality was 23.8%. Mortality was associated with increasing age (odds ratio, 1.03 per year [95% CI, 1.02-1.04]), the presence of pleuropulmonary infection (2.3 [1.4-3.7]), transfer to an intensive care unit (3.2 [2.1-5.0]), and failure to receive appropriate antimicrobial therapy within 24 hours of MRSA identification (3.2 [2.1-5.0]); a skin/soft-tissue source of BSI was associated with decreased mortality (0.5 [0.3-0.9]). MRSA genotype and reduced susceptibility to vancomycin were not associated with risk of death. CONCLUSIONS This study provides additional insight into the relative impact of various host and microbial factors associated with mortality in patients with MRSA BSI. The results emphasize the importance of ensuring timely receipt of appropriate antimicrobial agents to reduce the risk of an adverse outcome.

Diagnosis and treatment of bacteremia and endocarditis due to Staphylococcus aureus. A clinical guideline from the Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC)

Both bacteremia and infective endocarditis caused by Staphylococcus aureus are common and severe diseases. The prognosis may darken not infrequently, especially in the presence of intracardiac devices or methicillin-resistance. Indeed, the optimization of the antimicrobial therapy is a key step in the outcome of these infections. The high rates of treatment failure and the increasing interest in the influence of vancomycin susceptibility in the outcome of infections caused by both methicillin-susceptible and -resistant isolates has led to the research of novel therapeutic schemes. Specifically, the interest raised in recent years on the new antimicrobials with activity against methicillin-resistant staphylococci has been also extended to infections caused by susceptible strains, which still carry the most important burden of infection. Recent clinical and experimental research has focused in the activity of new combinations of antimicrobials, their indication and role still being debatable. Also, the impact of an appropriate empirical antimicrobial treatment has acquired relevance in recent years. Finally, it is noteworthy the impact of the implementation of a systematic bundle of measures for improving the outcome. The aim of this clinical guideline is to provide an ensemble of recommendations in order to improve the treatment and prognosis of bacteremia and infective endocarditis caused by S. aureus, in accordance to the latest evidence published.

Incidence and outcome of inappropriate in-hospital empiric antibiotics for severe infection: a systematic review and meta-analysis

INTRODUCTION

The aims of this study were to explore the incidence of in-hospital inappropriate empiric antibiotic use in patients with severe infection and to identify its relationship with patient outcomes.

METHODS

Medline (from 2004 to 2014) was systematically searched by using predefined inclusion criteria. Reference lists of retrieved articles were screened for additional relevant studies. The systematic review included original articles reporting a quantitative measure of the association between the use of (in)appropriate empiric antibiotics in patients with severe in-hospital infections and their outcomes. A meta-analysis, using a random-effects model, was conducted to quantify the effect on mortality by using risk ratios.

RESULTS

In total, 27 individual articles fulfilled the inclusion criteria. The percentage of inappropriate empiric antibiotic use ranged from 14.1% to 78.9% (Q1-Q3: 28.1% to 57.8%); 13 of 27 studies (48.1%) described an incidence of 50% or more. A meta-analysis for 30-day mortality and in-hospital mortality showed risk ratios of 0.71 (95% confidence interval 0.62 to 0.82) and 0.67 (95% confidence interval 0.56 to 0.80), respectively. Studies with outcome parameter 28-day and 60-day mortality reported significantly (P ≤0.02) higher mortality rates in patients receiving inappropriate antibiotics. Two studies assessed the total costs, which were significantly higher in both studies (P ≤0.01).

CONCLUSIONS

This systematic review with meta-analysis provides evidence that inappropriate use of empiric antibiotics increases 30-day and in-hospital mortality in patients with a severe infection.

Timely empiric antimicrobials are associated with faster microbiologic clearance in preterm neonates with late-onset bloodstream infections

AIM

The impact of timely empiric antimicrobial therapy on neonates is unclear. Our aim was to examine rates of effective timely empiric antimicrobial therapy on preterm neonates, together with the associated outcomes.

METHODS

We performed a single-centre retrospective study of preterm infants (<32 weeks of gestational age) with a late-onset (>72 h of age) bloodstream infection (BSI). Empiric antimicrobial administration took place before the results of blood culture were available and its timing was determined by the electronic medical records.

RESULTS

Our cohort (n = 105) was predominantly female (59%) and black (83%) with a mean (SD) gestational age of 27.4 (2.3) weeks and birthweight of 948 (335) g. Effective empiric antimicrobials were initiated in 114 (69%) of 165 BSI episodes, and a third of the BSIs without empiric antimicrobials were found to be fungal. Both antimicrobial timing (r = 0.27, p = 0.002) and fungal organism (r = 0.35, p = 0.0001) showed significant correlations and were independently associated with time to clearance. Neither variable was associated with survival or length of stay.

CONCLUSION

Two-thirds of preterm infants with late-onset BSIs received effective empiric antimicrobials. Timely empiric antimicrobials were associated with shorter time to microbiologic clearance. These data suggest the need for standardised guidelines and quality improvement initiatives.

Evaluation of MRSASelect (™) chromogenic medium for the early detection of methicillin-resistant Staphylococcus aureus from blood cultures

INTRODUCTION

Staphylococcus aureus bacteremia is associated with considerable morbidity and mortality. In theory, reducing the turnaround time in reporting of methicillin-resistant S aureus (MRSA) among patients with bactermia could assist with the rapid optimization of antimicrobial therapy.

OBJECTIVE

To evaluate the sensitivity and specificity of MRSASelect (Bio-Rad Laboratories, USA), a chromogenic medium, in the early detection of MRSA from blood cultures growing Gram-positive cocci in clusters, and to confirm that routine use of this medium would, in fact, reduce turnaround time for MRSA identification.

METHODS

The present study was conducted at three microbiology laboratories in Manitoba. Between April 2010 and May 2011, positive blood cultures with Gram-positive cocci in clusters visualized on Gram stain were subcultured to both MRSASelect and routine media. MRSA isolates were identified using conventional microbiological methods from routine media and using growth with the typical colony morphology (pink colony) on MRSASelect medium.

RESULTS

A total of 490 blood cultures demonstrating Gram-positive cocci in clusters on Gram stain were evaluated. S aureus was recovered from 274 blood cultures, with 51 S aureus isolates (51 of 274 [18.6%]) identified as MRSA. MRSASelect medium had a sensitivity of 98%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.8% for the recovery and identification of MRSA directly from positive blood culture bottles. In addition, use of MRSASelect medium was found to improve turnaround time in the detection of MRSA by almost 24 h relative to conventional methods.

DISCUSSION

These data support the utility of MRSASelect medium for the rapid identification of MRSA from positive blood cultures. Further clinical studies are warranted to determine whether the improvement in turnaround time will result in a measurable reduction in suboptimal antimicrobial therapy and/or improvement in patient outcome.

Delays in appropriate antibiotic therapy for gram-negative bloodstream infections: a multicenter, community hospital study

BACKGROUND

Gram-negative bacterial bloodstream infection (BSI) is a serious condition with estimated 30% mortality. Clinical outcomes for patients with severe infections improve when antibiotics are appropriately chosen and given early. The objective of this study was to estimate the association of prior healthcare exposure on time to appropriate antibiotic therapy in patients with gram-negative BSI.

METHOD

We performed a multicenter cohort study of adult, hospitalized patients with gram-negative BSI using time to event analysis in nine community hospitals from 2003-2006. Event time was defined as the first administration of an antibiotic with in vitro activity against the infecting organism. Healthcare exposure status was categorized as community-acquired, healthcare-associated, or hospital-acquired. Time to appropriate therapy among groups of patients with differing healthcare exposure status was assessed using Kaplan-Meier analyses and multivariate Cox proportional hazards models.

RESULTS

The cohort included 578 patients with gram-negative BSI, including 320 (55%) healthcare-associated, 217 (38%) community-acquired, and 41 (7%) hospital-acquired infections. 529 (92%) patients received an appropriate antibiotic during their hospitalization. Time to appropriate therapy was significantly different among the groups of healthcare exposure status (log-rank p=0.02). Time to first antibiotic administration regardless of drug appropriateness was not different between groups (p=0.3). The unadjusted hazard ratios (HR) (95% confidence interval) were 0.80 (0.65-0.98) for healthcare-associated and 0.72 (0.63-0.82) for hospital-acquired, relative to patients with community-acquired BSI. In multivariable analysis, interaction was found between the main effect and baseline Charlson comorbidity index. When Charlson index was 3, adjusted HRs were 0.66 (0.48-0.92) for healthcare-associated and 0.57 (0.44-0.75) for hospital-acquired, relative to patients with community-acquired infections.

CONCLUSIONS

Patients with healthcare-associated or hospital-acquired BSI experienced delays in receipt of appropriate antibiotics for gram-negative BSI compared to patients with community-acquired BSI. This difference was not due to delayed initiation of antibiotic therapy, but due to the inappropriate choice of antibiotic.

Depression, anxiety, and moods of hospitalized patients under contact precautions

OBJECTIVE

To determine the association between contact precautions and depression or anxiety as well as feelings of anger, sadness, worry, happiness, or confusion.

DESIGN

Prospective frequency-matched cohort study.

SETTING

The University of Maryland Medical Center, a 662-bed tertiary care hospital in Baltimore, Maryland.

PARTICIPANTS

A total of 1,876 medical and surgical patients over the age of 18 years were approached; 528 patients were enrolled from January through November 2010, and 296 patients, frequency matched by hospital unit, completed follow-up on hospital day 3.

RESULTS

The primary outcome was Hospital Anxiety and Depression Scale (HADS) scores on hospital day 3, controlling for baseline HADS scores. Secondary moods were measured with visual analog mood scale diaries. Patients under contact precautions had baseline symptoms of depression 1.3 points higher (P<.01) and anxiety 0.8 points higher (P=.08) at hospital admission using HADS. Exposure to contact precautions was not associated with increased depression (P=.42) or anxiety (P=.25) on hospital day 3. On hospital day 3, patients under contact precautions were no more likely than unexposed patients to be angry (20% vs 20%; P=.99), sad (33% vs 38%; P=.45), worried (51% vs 46%; P=.41), happy (58% vs 67%; P=.14), or confused (23% vs 24%; P=.95).

CONCLUSIONS

Patients under contact precautions have more symptoms of depression and anxiety at hospital admission but do not appear to be more likely to develop depression, anxiety, or negative moods while under contact precautions. The use of contact precautions should not be restricted by the belief that contact precautions will produce more depression or anxiety.

Timing of initiating glycopeptide therapy for methicillin-Resistant Staphylococcus aureus bacteremia: the impact on clinical outcome

When a Staphylococcus-like organism (SLO) is microscopically found in Gram staining of blood culture (BC) specimen, it seems reasonable to administrate a glycopeptide (GP) for empirical therapy. The paper investigates the risk factors for 14-day mortality in patients with methicillin-resistance Staphylococcus aureus bacteremia (MRSAB) and clarifies the impact of the timing for initiating GP therapy. A retrospective study identifies patients with MRSAB (endocarditis was excluded) between 2006 and 2009. Patients were categorized as receiving GP at the interval before a preliminary BC report indicating the growth of SLO and the onward 24 hours or receiving GP 24 h after a preliminary BC report indicating the growth of SLO. Total 339 patients were enrolled. There was no difference on the 14-day overall or infection-related mortality rates at the time to administer GP. Multivariate analysis disclosed pneumonia (OR = 4.47; of 95% CI; of 2.09–9.58; P < 0.01) and high APACHE II score (OR, 2.81, with 95% CI, 1.19–6.65; P = 0.02) were independent risk factors for infection-related mortality. The mortality rate did not decrease following administrating GP immediately after a preliminary BC indicating SLO growth. An additional research for the optimal timing for initiating GP treatment is warranted.

Predicting risk for death from MRSA bacteremia

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is often fatal. To determine predictors of risk for death, we conducted a retrospective cohort study. We examined 699 episodes of MRSA bacteremia involving 603 patients admitted to an academic medical center in New York City during 2002-2007. Data came from chart reviews, hospital databases, and recultured frozen MRSA specimens. Among the 699 episodes, 55 were caused by vancomycin-intermediate resistant S. aureus strains, 55 by heteroresistant vancomycin-intermediate S. aureus strains, and 589 by non-vancomycin-resistant strains; 190 (31.5%) patients died. We used regression risk analysis to quantify the association between clinical correlates and death. We found that older age, residence in a nursing home, severe bacteremia, and organ impairment were independently associated with increased risk for death; consultation with an infectious disease specialist was associated with lower risk for death; and MRSA strain types were not associated with risk for death.

Characteristics and determinants of outcome of hospital-acquired bloodstream infections in intensive care units: the EUROBACT International Cohort Study

PURPOSE

The recent increase in drug-resistant micro-organisms complicates the management of hospital-acquired bloodstream infections (HA-BSIs). We investigated the epidemiology of HA-BSI and evaluated the impact of drug resistance on outcomes of critically ill patients, controlling for patient characteristics and infection management.

METHODS

A prospective, multicentre non-representative cohort study was conducted in 162 intensive care units (ICUs) in 24 countries.

RESULTS

We included 1,156 patients [mean ± standard deviation (SD) age, 59.5 ± 17.7 years; 65 % males; mean ± SD Simplified Acute Physiology Score (SAPS) II score, 50 ± 17] with HA-BSIs, of which 76 % were ICU-acquired. Median time to diagnosis was 14 [interquartile range (IQR), 7-26] days after hospital admission. Polymicrobial infections accounted for 12 % of cases. Among monomicrobial infections, 58.3 % were gram-negative, 32.8 % gram-positive, 7.8 % fungal and 1.2 % due to strict anaerobes. Overall, 629 (47.8 %) isolates were multidrug-resistant (MDR), including 270 (20.5 %) extensively resistant (XDR), and 5 (0.4 %) pan-drug-resistant (PDR). Micro-organism distribution and MDR occurrence varied significantly (p < 0.001) by country. The 28-day all-cause fatality rate was 36 %. In the multivariable model including micro-organism, patient and centre variables, independent predictors of 28-day mortality included MDR isolate [odds ratio (OR), 1.49; 95 % confidence interval (95 %CI), 1.07-2.06], uncontrolled infection source (OR, 5.86; 95 %CI, 2.5-13.9) and timing to adequate treatment (before day 6 since blood culture collection versus never, OR, 0.38; 95 %CI, 0.23-0.63; since day 6 versus never, OR, 0.20; 95 %CI, 0.08-0.47).

CONCLUSIONS

MDR and XDR bacteria (especially gram-negative) are common in HA-BSIs in critically ill patients and are associated with increased 28-day mortality. Intensified efforts to prevent HA-BSIs and to optimize their management through adequate source control and antibiotic therapy are needed to improve outcomes.

Characteristics and determinants of outcome of hospital-acquired bloodstream infections in intensive care units: the EUROBACT International Cohort Study

PURPOSE

The recent increase in drug-resistant micro-organisms complicates the management of hospital-acquired bloodstream infections (HA-BSIs). We investigated the epidemiology of HA-BSI and evaluated the impact of drug resistance on outcomes of critically ill patients, controlling for patient characteristics and infection management.

METHODS

A prospective, multicentre non-representative cohort study was conducted in 162 intensive care units (ICUs) in 24 countries.

RESULTS

We included 1,156 patients [mean ± standard deviation (SD) age, 59.5 ± 17.7 years; 65 % males; mean ± SD Simplified Acute Physiology Score (SAPS) II score, 50 ± 17] with HA-BSIs, of which 76 % were ICU-acquired. Median time to diagnosis was 14 [interquartile range (IQR), 7-26] days after hospital admission. Polymicrobial infections accounted for 12 % of cases. Among monomicrobial infections, 58.3 % were gram-negative, 32.8 % gram-positive, 7.8 % fungal and 1.2 % due to strict anaerobes. Overall, 629 (47.8 %) isolates were multidrug-resistant (MDR), including 270 (20.5 %) extensively resistant (XDR), and 5 (0.4 %) pan-drug-resistant (PDR). Micro-organism distribution and MDR occurrence varied significantly (p < 0.001) by country. The 28-day all-cause fatality rate was 36 %. In the multivariable model including micro-organism, patient and centre variables, independent predictors of 28-day mortality included MDR isolate [odds ratio (OR), 1.49; 95 % confidence interval (95 %CI), 1.07-2.06], uncontrolled infection source (OR, 5.86; 95 %CI, 2.5-13.9) and timing to adequate treatment (before day 6 since blood culture collection versus never, OR, 0.38; 95 %CI, 0.23-0.63; since day 6 versus never, OR, 0.20; 95 %CI, 0.08-0.47).

CONCLUSIONS

MDR and XDR bacteria (especially gram-negative) are common in HA-BSIs in critically ill patients and are associated with increased 28-day mortality. Intensified efforts to prevent HA-BSIs and to optimize their management through adequate source control and antibiotic therapy are needed to improve outcomes.

Healthcare-associated infection and hospital readmission

OBJECTIVE

Hospital readmissions are a current target of initiatives to reduce healthcare costs. This study quantified the association between having a clinical culture positive for 1 of 3 prevalent hospital-associated organisms and time to hospital readmission.

DESIGN

Retrospective cohort study.

PATIENTS AND SETTING

Adults admitted to an academic, tertiary care referral center from January 1, 2001, through December 31, 2008.

METHODS

The primary exposure of interest was a clinical culture positive for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), or Clostridium difficile obtained more than 48 hours after hospital admission during the index hospital stay. The primary outcome of interest was time to readmission to the index facility. Multivariable Cox proportional hazards models were used to model the adjusted association between positive clinical culture result and time to readmission and to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Among 136,513 index admissions, the prevalence of hospital-associated positive clinical culture result for 1 of the 3 organisms of interest was 3%, and 35% of patients were readmitted to the index facility within 1 year after discharge. Patients with a positive clinical culture obtained more than 48 hours after hospital admission had an increased hazard of readmission (HR, 1.40; 95% CI, 1.33-1.46) after adjusting for age, sex, index admission length of stay, intensive care unit stay, Charlson comorbidity index, and year of hospital admission.

CONCLUSIONS

Patients with healthcare-associated infections may be at increased risk of hospital readmission. These findings may be used to impact health outcomes after discharge from the hospital and to encourage better infection prevention efforts.

Predictors of mortality in Staphylococcus aureus Bacteremia

Staphylococcus aureus bacteremia (SAB) is an important infection with an incidence rate ranging from 20 to 50 cases/100,000 population per year. Between 10% and 30% of these patients will die from SAB. Comparatively, this accounts for a greater number of deaths than for AIDS, tuberculosis, and viral hepatitis combined. Multiple factors influence outcomes for SAB patients. The most consistent predictor of mortality is age, with older patients being twice as likely to die. Except for the presence of comorbidities, the impacts of other host factors, including gender, ethnicity, socioeconomic status, and immune status, are unclear. Pathogen-host interactions, especially the presence of shock and the source of SAB, are strong predictors of outcomes. Although antibiotic resistance may be associated with increased mortality, questions remain as to whether this reflects pathogen-specific factors or poorer responses to antibiotic therapy, namely, vancomycin. Optimal management relies on starting appropriate antibiotics in a timely fashion, resulting in improved outcomes for certain patient subgroups. The roles of surgery and infectious disease consultations require further study. Although the rate of mortality from SAB is declining, it remains high. Future international collaborative studies are required to tease out the relative contributions of various factors to mortality, which would enable the optimization of SAB management and patient outcomes.

Comparative effectiveness of nafcillin or cefazolin versus vancomycin in methicillin-susceptible Staphylococcus aureus bacteremia

Background

The high prevalence of methicillin-resistant S. aureus (MRSA) has led clinicians to select antibiotics that have coverage against MRSA, usually vancomycin, for empiric therapy for suspected staphylococcal infections. Clinicians often continue vancomycin started empirically even when methicillin-susceptible S. aureus (MSSA) strains are identified by culture. However, vancomycin has been associated with poor outcomes such as nephrotoxicity, persistent bacteremia and treatment failure. The objective of this study was to compare the effectiveness of vancomycin versus the beta-lactam antibiotics nafcillin and cefazolin among patients with MSSA bacteremia. The outcome of interest for this study was 30-day in-hospital mortality.

Methods

This retrospective cohort study included all adult in-patients admitted to a tertiary-care facility between January 1, 2003 and June 30, 2007 who had a positive blood culture for MSSA and received nafcillin, cefazolin or vancomycin. Cox proportional hazard models were used to assess independent mortality hazards comparing nafcillin or cefazolin versus vancomycin. Similar methods were used to estimate the survival benefits of switching from vancomycin to nafcillin or cefazolin versus leaving patients on vancomycin. Each model included statistical adjustment using propensity scores which contained variables associated with an increased propensity to receive vancomycin.

Results

267 patients were included; 14% (38/267) received nafcillin or cefazolin, 51% (135/267) received both vancomycin and either nafcillin or cefazolin, and 35% (94/267) received vancomycin. Thirty (11%) died within 30 days. Those receiving nafcillin or cefazolin had 79% lower mortality hazards compared with those who received vancomycin alone (adjusted hazard ratio (HR): 0.21; 95% confidence interval (CI): 0.09, 0.47). Among the 122 patients who initially received vancomycin empirically, those who were switched to nafcillin or cefazolin (66/122) had 69% lower mortality hazards (adjusted HR: 0.31; 95% CI: 0.10, 0.95) compared to those who remained on vancomycin.

Conclusions

Receipt of nafcillin or cefazolin was protective against mortality compared to vancomycin even when therapy was altered after culture results identified MSSA. Convenience of vancomycin dosing may not outweigh the potential benefits of nafcillin or cefazolin in the treatment of MSSA bacteremia.

Do contact precautions cause depression? A two-year study at a tertiary care medical centre

Contact precautions, used to reduce the transmission of infectious diseases, include the wearing of gowns and gloves for room entry. Previous small studies have shown an association between contact precautions and increased symptoms of depression and anxiety. A retrospective cohort of all patients admitted to a tertiary care centre over two years was studied to assess the relationship between contact precautions and depression or anxiety. During the two-year period, there were 70,275 admissions including 28,564 unique non-intensive-care-unit (ICU), non-psychiatric admissions. After adjusting for potential confounders, contact precautions were associated with depression [odds ratio (OR) 1.4, 95% confidence interval (CI) 1.2-1.5] but not with anxiety (OR 0.8, 95% CI 0.7-1.1) in the non-ICU population. Depression was 40% more prevalent among general inpatients on contact precautions.

Optimizing delivery of care for patients with MRSA infection: focus on transitions of care

Staphylococcus aureus is among the most prevalent pathogens isolated from hospitalized patients; those infected with methicillin-resistant strains have longer hospital stays and higher total costs compared with those infected by methicillin-susceptible strains. A multidisciplinary team of health care providers, including hospitalists and other hospital-based physicians, clinical pharmacists, infectious disease specialists, infection control professionals, and case managers, is key to improving treatment and outcomes in these patients. Optimizing transitions of care for hospitalized patients with S aureus infections can improve quality and reduce total costs of care. Hospital length of stay can be shortened by initiating timely, appropriate empiric therapy and by transitioning suitable patients to outpatient antimicrobial therapy. The number of hospitalizations can be reduced by identifying patients who are suitable candidates for initial outpatient antimicrobial therapy. Consistent with good antimicrobial stewardship, the risk of resistance can be minimized by de-escalating empiric therapy to a more narrow-spectrum agent once culture and susceptibility testing results are known. There are several antimicrobial agents available for the management of S aureus infections, including methicillin-resistant S aureus. Consideration of these agents' characteristics may facilitate optimal transition of patients through health care settings.

Staphylococcus aureus bacteraemia--Nationwide assessment of treatment adequacy and outcome

OBJECTIVES

To assess the treatment adequacy for Staphylococcus aureus bacteraemia (SAB) and its association with outcome on a whole population basis.

METHODS

All individuals ≥18 years old diagnosed with SAB in Iceland between December 1 2003 and November 30 2008 were retrospectively identified. Clinical data was collected from medical records and adequacy of antibiotic treatment based on antibiotic choice, dose, administration route and treatment duration.

RESULTS

Empirical therapy was considered adequate in 262 of 325 (81%) SAB episodes, with no correlation to outcome. The complete antibiotic treatment was deemed adequate in 147 of 279 (53%) episodes. Among patients with complicated SAB median duration of active intravenous therapy was 14 days in those experiencing relapse compared to 30 days in patients without relapse (p = 0.03). No patient died after completing adequate treatment compared to 4 (3.0%) following inadequate therapy (p = 0.01). Despite no overall change being seen in antibiotic treatment, 30-day mortality decreased from 25.0 to 6.8% from first to last year of study (p = 0.001).

CONCLUSION

Appropriate antibiotic therapy for SAB was associated with lower relapse rates and mortality. Although treatment adequacy was regarded as insufficient in half of cases, mortality of SAB in Iceland is amongst the lowest recorded.

SUMMARY

In a national study of S. aureus bacteraemia the antibiotic treatment was judged inadequate in 53% of episodes, while appropriate treatment was associated with lower relapse rate and mortality. Despite this, the mortality in Iceland is among the lowest reported.

Increased mortality with accessory gene regulator (agr) dysfunction in Staphylococcus aureus among bacteremic patients

Accessory gene regulator (agr) dysfunction in Staphylococcus aureus has been associated with a longer duration of bacteremia. We aimed to assess the independent association between agr dysfunction in S. aureus bacteremia and 30-day in-hospital mortality. This retrospective cohort study included all adult inpatients with S. aureus bacteremia admitted between 1 January 2003 and 30 June 2007. Severity of illness prior to culture collection was measured using the modified acute physiology score (APS). agr dysfunction in S. aureus was identified semiquantitatively by using a δ-hemolysin production assay. Cox proportional hazard models were used to measure the association between agr dysfunction and 30-day in-hospital mortality, statistically adjusting for patient and pathogen characteristics. Among 814 patient admissions complicated by S. aureus bacteremia, 181 (22%) patients were infected with S. aureus isolates with agr dysfunction. Overall, 18% of patients with agr dysfunction in S. aureus died, compared to 12% of those with functional agr in S. aureus (P = 0.03). There was a trend toward higher mortality among patients with S. aureus with agr dysfunction (adjusted hazard ratio [HR], 1.34; 95% confidence interval [CI], 0.87 to 2.06). Among patients with the highest APS (scores of >28), agr dysfunction in S. aureus was significantly associated with mortality (adjusted HR, 1.82; 95% CI, 1.03 to 3.21). This is the first study to demonstrate an independent association between agr dysfunction and mortality among severely ill patients. The δ-hemolysin assay examining agr function may be a simple and inexpensive approach to predicting patient outcomes and potentially optimizing antibiotic therapy.

Systematic review and meta-analysis of the efficacy of appropriate empiric antibiotic therapy for sepsis

Quantifying the benefit of early antibiotic treatment is crucial for decision making and can be assessed only in observational studies. We performed a systematic review of prospective studies reporting the effect of appropriate empirical antibiotic treatment on all-cause mortality among adult inpatients with sepsis. Two reviewers independently extracted data. Risk of bias was assessed using the Newcastle-Ottawa score. We calculated unadjusted odds ratios (ORs) with 95% confidence intervals for each study and extracted adjusted ORs, with variance, methods, and covariates being used for adjustment. ORs were pooled using random-effects meta-analysis. We examined the effects of methodological and clinical confounders on results through subgroup analysis or mixed-effect meta-regression. Seventy studies were included, of which 48 provided an adjusted OR for inappropriate empirical antibiotic treatment. Inappropriate empirical antibiotic treatment was associated with significantly higher mortality in the unadjusted and adjusted comparisons, with considerable heterogeneity occurring in both analyses (I(2) > 70%). Study design, time of mortality assessment, the reporting methods of the multivariable models, and the covariates used for adjustment were significantly associated with effect size. Septic shock was the only clinical variable significantly affecting results (it was associated with higher ORs). Studies adjusting for background conditions and sepsis severity reported a pooled adjusted OR of 1.60 (95% confidence interval = 1.37 to 1.86; 26 studies; number needed to treat to prevent one fatal outcome, 10 patients [95% confidence interval = 8 to 15]; I(2) = 46.3%) given 34% mortality with inappropriate empirical treatment. Appropriate empirical antibiotic treatment is associated with a significant reduction in all-cause mortality. However, the methods used in the observational studies significantly affect the effect size reported. Methods of observational studies assessing the effects of antibiotic treatment should be improved and standardized.

Importance of appropriate empirical antibiotic therapy for methicillin-resistant Staphylococcus aureus bacteraemia

OBJECTIVES

To document the effects of appropriate and inappropriate empirical antibiotic therapy on mortality in a cohort of patients with bacteraemia due to methicillin-resistant Staphylococcus aureus (MRSA) and to summarize effects with previous studies.

METHODS

In the retrospective cohort study, episodes of clinically significant MRSA bacteraemia during a 15 year period were included. Polymicrobial episodes were excluded unless MRSA was isolated in more than one bottle and co-pathogens were given appropriate empirical antibiotic treatment. Appropriate empirical treatment was defined as matching in vitro susceptibility and started within 48 h of blood-culture taking, except for single aminoglycosides or rifampicin. We assessed univariate and multivariate associations between appropriate empirical therapy and 30 day all-cause mortality. Multivariable analysis was conducted using backward stepwise logistic regression. We reviewed all studies assessing the effects of appropriate empirical antibiotic treatment on mortality for MRSA infections and compiled adjusted odds ratios (ORs) using a random effects meta-analysis.

RESULTS

Five hundred and ten episodes of MRSA bacteraemia were included. There were no cases of community-acquired infection. The 30 day mortality was 43.9% (224/510) and was stable throughout the study period. Mortality was significantly higher among patients receiving inappropriate (168/342, 49.1%) compared with those receiving appropriate (56/168, 33.3%) empirical antibiotic treatment, P = 0.001. In the adjusted analysis the OR was 2.15 [95% confidence interval (CI) 1.34-3.46]. Pooling of six studies using adequate methodology for the adjusted analysis resulted in an OR of 1.98 (95% CI 1.62-2.44).

CONCLUSIONS

Appropriate empirical antibiotic treatment has a significant survival benefit in MRSA bacteraemia. Treatment guidelines should consider this benefit.