Clinical and microbiological characteristics of persistent Staphylococcus aureus bacteremia, risk factors for mortality, and the role of CD4+ T cells.

This study evaluated the determinants of mortality and the T cell immune response in patients with persistent Staphylococcus aureus bacteremia (SAB). This was a prospective cohort study and patients with confirmed SAB were enrolled from 2008 to 2020. We compared clinical, microbiological, and genotypic features between surviving and deceased patients with persistent SAB. The concentrations of cytokines and the proportions of IFN-γ secreting CD4+ T cells were measured serially during the bacteremia period. Of the 1760 patients, 242 had persistent bacteremia (PB), and 49 PB patients died within 30 days. In the multivariate analysis, the APACHE II score and female sex were independently associated with 30 days mortality. The level of IL-10 was significantly increased in the plasma of patients with a high Pitt bacteremia score and those who died within 12 weeks from the index day. The proportion of IFN-γ-secreting CD4+ T cells were the highest just before the positive-to-negative conversion of blood cultures in patients with a low Pitt bacteremia score and those who survived for 12 weeks. The level of IL-10 is correlated with clinical outcomes in PB patients. IFN-γ secreting CD4+ T cells might play a pivotal role in SAB PB.

Predictive Value of Vancomycin AUC24/MIC Ratio for 30-day Mortality in Patients with Severe or Complicated Methicillin-Resistant Staphylococcus aureus Infections: A Multicenter Retrospective Study.

BACKGROUND: Although vancomycin is typically employed against methicillin-resistant Staphylococcus aureus (MRSA) infections, the optimal ratio of 24-h area under the concentration-time curve to minimum inhibitory concentration (AUC24/MIC) for severe or complicated infections lacks clear guideline recommendations. This study aimed to determine the target AUC24/MIC ratio associated with treatment outcomes of infections treated with vancomycin. METHODS: This retrospective multicenter cohort study included adult patients receiving ≥ 5 days of vancomycin for severe/complicated MRSA infections (e.g., osteoarticular, pulmonary, endocarditis, etc.) between January 2018 and December 2023. The primary outcome was 30-day mortality, with secondary outcomes including clinical success, microbiological eradication, and nephrotoxicity. Receiver operating characteristic (ROC) curve analysis was used to identify the AUC24/MIC cutoff for 30-day mortality. Multivariate regression analysis was used to determine association between AUC24/MIC and outcomes. RESULTS: This study included 82 patients. ROC identified a target AUC24/MIC of ≥ 505 for 30-day mortality. The overall 30-day mortality rate (22.0%) was significantly higher for below average AUC24/MIC cutoff (34.1%) than for above AUC24/MIC cutoff group (9.8%). Multivariate analysis confirmed AUC24/MIC of < 505 as an independent predictor (adjusted odds ratio, 5.001; 95% confidence interval, 1.335-18.75). The clinical success rate differed significantly between below- and above-cutoff groups, whereas microbiological eradication tended to favor the above-cutoff group. The nephrotoxicity rates were comparable between groups. CONCLUSIONS: In treating severe/complicated MRSA infections, vancomycin AUC24/MIC ratio ≥ 505 was independently associated with favorable 30-day mortality. Given the retrospective nature of this study, further prospective studies are essential to confirm the reliability of the target AUC24/MIC ratios.

Risk of infective endocarditis and complicated infection in Staphylococcus aureus bacteremia - a retrospective cohort study on the role of bacteriuria.

PURPOSE: S. aureus bacteremia (SAB) is a common and severe infection with high mortality and morbidity. The clinical relevance of the finding of concurrent S. aureus bacteriuria (SABU) is debated. The goal of this study was to analyze whether a concurrent SABU is associated with complicated SAB, infective endocarditis (IE) and mortality. METHODS: We conducted a retrospective cohort study, reviewing medical charts of all episodes of SAB in patients > 18 years in the region of Skåne, Sweden, between 1st of January and 31st of June 2020. Episodes where a concurrent urine culture was performed were included for analysis. An episode was considered as complicated SAB if there was either attributable mortality, recurrent infection, embolic stroke, or occurrence of a complicated focus of infection. RESULTS: During the study period, there were 279 episodes of SAB. 154 episodes met the eligibility criteria, of whom 37 (24%) had concurrent SABU. In 78 episodes (51%), the patients had a complicated SAB. There was a significantly lower proportion of complicated SAB for episodes with concurrent SABU (32%), compared to episodes without concurrent SABU (56%), p-value 0.014. Moreover, in the cohort there were 11 episodes (7.1%) of IE and a 30 days mortality rate of 16%, with no difference between the groups with or without SABU. CONCLUSIONS: There is an association between concurrent SABU and a decreased risk for complicated SAB among patients with SAB. This study found no significant association between SABU and neither IE nor mortality for patients with SAB.

Effectiveness and safety of cefazolin versus cloxacillin in endocarditis due to methicillin-susceptible Staphylococcus spp.: a multicenter propensity weighted cohort study.

PURPOSE: To compare the effectiveness and safety of cefazolin versus cloxacillin for the treatment of infective endocarditis (IE) due to methicillin-sensitive Staphylococci (MSS). METHODS: Data were retrospectively collected on patients treated for a definite MSS endocarditis who received cefazolin or cloxacillin for at least 10 consecutive days in six French hospitals between January-1 2014 and December-31 2020. The primary endpoint was treatment failure defined as a composite of death within 90 days of starting antibiotherapy, or embolic event during antibiotherapy, or relapse of IE within 90 days of stopping antibiotherapy. We used Cox regression adjusted for the inverse probability of treatment weighting of receiving cefazolin. RESULTS: 192 patients were included (median age 67.8 years). IE was caused by S.aureus in 175 (91.1%) and by coagulase-negative staphylococci in 17 (8.9%). Ninety-four patients (48.9%) received cefazolin, and 98 (51%) received cloxacillin. 34 patients (34.7%) with cefazolin and 26 (27.7%) with cloxacillin met the composite primary endpoint, with no significant differences between groups (adjusted HR = 1.13, 95% CI 0.63 to 2.03). There were no significant differences in secondary efficacy endpoints or biological safety events. CONCLUSION: The effectiveness of cefazolin did not significantly differ from cloxacillin for the treatment of MSS endocarditis.

Short versus long duration of ceftaroline combination therapy and outcomes in persistent or high-grade MRSA bacteremia: A retrospective single-center study.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is associated with high mortality rates. Despite antibiotic therapy, persistent bacteremia is challenging to treat. Combination therapy with ceftaroline has emerged as a potential treatment option; however, the optimal duration and clinical implications after bacteremia clearance are unknown. METHODS: This retrospective cohort study examined patients with high-grade or persistent MRSA bacteremia who were treated with ceftaroline combination therapy at the University of New Mexico Hospital between January 2014 and June 2021. Patients were categorized into short- (<7 days) or long-duration (≥7 days) groups based on the duration of combination therapy after bacteremia clearance. Outcomes included 30-day all-cause mortality, bacteremia recurrence, post-bacteremia clearance length of stay, and adverse events. RESULTS: A total of 32 patients were included in this study. The most common sources of bacteremia were bone/joint and endovascular (28.1%, 9/32 each). The median duration of combination therapy after clearance was seven days (IQR 2.8, 11). Patients in the long-duration group had a lower Charlson comorbidity index (1.0 vs 5.5, p = 0.017) than those in the short-duration group. After adjusting for confounders, there was no significant difference in the 30-day all-cause mortality between the groups (AOR 0.17, 95% CI 0.007-1.85, p = 0.18). No association was found between combination therapy duration and recurrence (OR 2.53, 95% CI 0.19-inf, p = 0.24) or adverse drug events (OR 3.46, 95% CI 0.39-74.86, p = 0.31). After controlling for total hospital length of stay, there was no significant difference in the post-bacteremia clearance length of stay between the two groups (p = 0.37). CONCLUSIONS: Prolonging ceftaroline combination therapy after bacteremia clearance did not significantly improve outcomes in patients with persistent or high-grade MRSA bacteremia. The limitations of this study warrant cautious interpretation of its results. Larger studies are needed to determine the optimal duration and role of combination therapy for this difficult-to-treat infection.

Impact of the implementation of the Intelligent Antimicrobial System (iAMS) on clinical outcomes among patients with bacteraemia caused by methicillin-resistant Staphylococcus aureus.

OBJECTIVES: This study aimed to investigate the clinical impact of the Intelligent Antimicrobial System (iAMS) on patients with bacteraemia due to methicillin-resistant (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA). METHODS: A total of 1008 patients with suspected SA infection were enrolled before and after the implementation of iAMS. Among them, 252 with bacteraemia caused by SA, including 118 in the iAMS and 134 in the non-iAMS groups, were evaluated. RESULTS: The iAMS group exhibited a 5.2% (from 55.2% to 50.0%; P = 0.96) increase in the 1-year survival rate. For patients with MRSA and MSSA compared to the non-iAMS group, the 1-year survival rate increased by 17.6% (from 70.9% to 53.3%; P = 0.41) and 7.0% (from 52.3% to 45.3%; P = 0.57), respectively, both surpassing the rate of the non-iAMS group. The iAMS intervention resulted in a higher long-term survival rate (from 70.9% to 52.3%; P = 0.984) for MRSA patients than for MSSA patients. MRSA patients experienced a reduced length of hospital stay (from 23.3% to 35.6%; P = 0.038), and the 45-day discharge rate increased by 20.4% (P = 0.064). Furthermore, the intervention resulted in a significant 97.3% relative decrease in near miss medication incidents reported by pharmacists (P = 0.013). CONCLUSIONS: Implementation of iAMS platform improved long-term survival rates, discharge rates, hospitalization days, and medical cost (although no significant differences were observed) among patients with MRSA bacteraemia. Additionally, it demonstrated significant benefits in ensuring drug safety.

Community-Acquired Staphylococcus aureus Bacteremia Among People Who Inject Drugs: A National Cohort Study in England, 2017-2020.

BACKGROUND: People who inject drugs (PWID) are at increased risk of community-acquired Staphylococcus aureus bacteremia (CA-SAB), but little is known about clinical outcomes of CA-SAB in PWID compared with the wider population of patients with CA-SAB. METHODS: Three national datasets were linked to provide clinical and mortality data on patients hospitalized with CA-SAB in England between 1 January 2017 and 31 December 2020. PWID were identified using the International Classification of Diseases, Tenth Revision code for "mental health and behavioral disorder due to opioid use" (F11). Multivariable logistic regression was used to estimate adjusted odds ratios (aORs) for associations of PWID with 30-day all-cause mortality and 90-day hospital readmission. RESULTS: In 10 045 cases of CA-SAB, 1612 (16.0%) were PWID. Overall, 796 (7.9%) patients died within 30 days of CA-SAB admission and 1189 (11.8%) patients were readmitted to hospital within 90 days of CA-SAB. In those without infective endocarditis, there was strong evidence of lower odds of mortality among PWID compared with non-PWID (aOR, 0.47 [95% confidence interval {CI}: .33-.68]; P < .001), whereas there was no association in CA-SAB case fatality with endocarditis (aOR, 1.40 [95% CI: .87-2.25]; P = .163). PWID were less likely to be readmitted within 90 days of CA-SAB (aOR, 0.79 [95% CI: .65-.95]; P = .011). CONCLUSIONS: In this large cohort study of patients with CA-SAB in England, PWID had lower odds of death in the absence of endocarditis and lower odds of readmission within 90 days compared to non-PWID patients. This study highlights the overrepresentation of PWID among patients with CA-SAB nationally.

Validation of a new risk stratification system-based management for methicillin-resistant Staphylococcus aureus bacteraemia: analysis of a multicentre prospective study.

PURPOSE: Distinguishing between complicated and uncomplicated Staphylococcus aureus bacteraemia (SAB) is therapeutically essential. However, this distinction has limitations in reflecting the heterogeneity of SAB and encouraging targeted diagnostics. Recently, a new risk stratification system for SAB metastatic infection, involving stepwise approaches to diagnosis and treatment, has been suggested. We assessed its applicability in methicillin-resistant SAB (MRSAB) patients. METHODS: We retrospectively analysed data of a 3-year multicentre, prospective cohort of hospitalised patients with MRSAB. We classified the patients into three risk groups: low, indeterminate, and high, based on the new system and compared between-group management and outcomes. RESULTS: Of 380 patients with MRSAB, 6.3% were classified as low-, 7.6% as indeterminate-, and 86.1% as high-risk for metastatic infection. No metastatic infection occurred in the low-, 6.9% in the indeterminate-, and 19.6% in the high-risk groups (P < 0.001). After an in-depth diagnostic work-up, patients were finally diagnosed as 'without metastatic infection (6.3%)', 'with metastatic infection (17.4%)', and 'uncertain for metastatic infection (76.3%)'. 30-day mortality increased as the severity of diagnosis shifted from 'without metastatic infection' to 'uncertain for metastatic infection' and 'with metastatic infection' (P = 0.09). In multivariable analysis, independent factors associated with metastatic complications were suspicion of endocarditis in transthoracic echocardiography, clinical signs of metastatic infection, Pitt bacteraemia score ≥ 4, and persistent bacteraemia. CONCLUSIONS: The new risk stratification system shows promise in predicting metastatic complications and guiding work-up and management of MRSAB. However, reducing the number of cases labelled as 'high-risk' and 'uncertain for metastatic infection' remains an area for improvement.

Effects of infectious disease consultation and antimicrobial stewardship program at a Japanese cancer center: An interrupted time-series analysis.

In cancer patients, appropriate diagnosis and management of infection are frequently challenging owing to subtle or atypical presentation. We investigated the effectiveness of infectious disease (ID) consultations and the Antimicrobial Stewardship Program (ASP) in a Japanese cancer center. This 36-month-period, single-institution, interrupted time series analysis was retrospectively conducted during April 1, 2018-March 31, 2021, to evaluate a two-phase intervention: Phase 1 (notification of antimicrobials by the infection control team) and Phase 2 (establishing an ID consultation service and implementing ASP). Among 32,202 patients hospitalized, 22,096 and 10,106 hospitalizations occurred at baseline and during intervention period, respectively. The Antimicrobial Stewardship Team (AST) provided feedback on specific broad-spectrum antimicrobials in 913 instances (347 appropriate [38%]; 566 inappropriate [62%]), and 440 ID consultations were completed, with a 75% overall acceptance rate for AST suggestions. In Phase 2, monthly carbapenem days of therapy (CAR-DOT) decreased significantly, and narrow-spectrum antibiotic usage increased significantly in both trend and level; monthly DOT of antipseudomonal agents decreased significantly in trend. The results of these analyses of antimicrobial use are consistent with the DOT-based data based on antimicrobial use density (AUD). The total number of inpatient specimens increased significantly; the trend of multidrug-resistant Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus infections decreased, without changes in the incidence of other resistant organisms, all-cause in-hospital mortality, and length of stay. Actual and adjusted CAR purchase costs per patient-day decreased without significant changes in the actual and adjusted purchase cost per patient-day for all intravenous antimicrobials. Combining ID consultation and ASP reduced carbapenem use without negative patient outcomes. Their implementation could facilitate establishment of safe cancer treatment facilities in Japan and improve prognosis in cancer patients.

Fatal SARS-CoV-2-Associated Panton-Valentine Leukocidin-producing Staphylococcal Bacteremia: A Nationwide Multicenter Cohort Study.

We reviewed all cases of Panton-Valentine leukocidin-producing Staphylococcus aureus (PVL-SA) bacteremia in Danish children between 2016 and 2021. We found 2 fatal cases with preceding viral prodrome due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Given the usual benign course of SARS-CoV-2 infection in children, awareness of possible superinfection with PVL-SA in a child with rapid deterioration is crucial to ensure adequate treatment, including antimicrobial drugs with antitoxin effect.

Distance Between Home and the Admitting Hospital and Its Effect on Survival of Low Socioeconomic Status Population With Staphylococcus aureus Bacteremia.

OBJECTIVE: Bacteremia is the presence of bacteria in the bloodstream. The objective of this study was to determine the relationship between low socioeconomic status (SES) and the epidemiology, process of care, and outcomes of patients with Staphylococcus aureus bacteremia (SAB). METHODS: We conducted a multicenter, retrospective, cohort study that evaluated adult patients with SAB in 3 Los Angeles County hospitals from July 15, 2012, through May 31, 2018. We determined SES (low SES, intermediate SES, and high SES) for each patient and compared sociodemographic and epidemiologic characteristics, management of care received by patients with SAB (ie, process of care), and outcomes. We used a Cox proportional hazards model to determine predictors of 30-day mortality for each SES group. RESULTS: Of 915 patients included in the sample, 369 (40%) were in the low-SES group, 294 (32%) in the intermediate-SES group, and 252 (28%) in the high-SES group. Most significant predictors of 30-day mortality in the Cox proportional hazards model were admission to an intensive care unit (hazard ratio [HR] = 9.04; 95% CI, 4.26-19.14), Pitt bacteremia score ≥4 indicating critical illness (HR = 4.30; 95% CI, 2.49-7.44), having ≥3 comorbidities (HR = 2.05; 95% CI, 1.09-3.85), and advanced age (HR = 1.03; 95% CI, 1.01-1.05). Distance between home and admitting hospital affected mortality only in the low-SES group (HR = 1.02; 95% CI, 1.00-1.02). CONCLUSIONS: SES did not independently affect the outcome of SAB; however, the farther the patient's residence from the hospital, the greater the negative effect on survival in a low-SES population. Our findings underscore the need to develop multipronged, targeted public health efforts for populations that have transportation barriers to health care.

Penicillin versus anti-staphylococcal beta-lactams for penicillin-susceptible Staphylococcus aureus blood stream infections: a retrospective cohort study.

The objective of the study is to assess the efficacy and tolerability of penicillins compared to anti-staphylococcal beta-lactams for treatment of penicillin-susceptible Staphylococcus aureus bloodstream infections (PSSA BSI). A retrospective cohort study was conducted of 140 sequential PSSA BSI presenting to a local health district (90 cases included). Penicillin susceptibility was confirmed by disc diffusion, Vitek® and Nitrocefin beta-lactamase methods. Clinical information regarding comorbidities and infection complexity was recorded. Antibiotic choice, dosage and duration were reviewed. Outcomes were compared according to the definitive treatment with either penicillin or ASBLs. The primary outcome was 30-day mortality. Secondary outcomes included renal injury, microbiological relapse and treatment tolerability. Ninety patients met inclusion criteria and were included in subsequent analysis. Of PSSA BSI, 69% were community acquired. Eighty-two percent had complex PSSA infections. The average duration of bacteraemia was 2.8 days (SD = 1.8 days). Sixty-six patients received definitive penicillin treatment, with a mean of 3.5 days of empiric antibiotics prior to penicillin. Twenty-four patients received definitive ASBL treatment (11 cefazolin, 13 flucloxacillin). There was no difference in 30-day mortality between groups (p = 1). There was no difference in renal injury (p > 0.5), hospital length of stay (p = 0.59) or microbiological relapse within 1 year (p = 0.17). Penicillin treatment was well tolerated. Our data supports penicillin as a suitable and well-tolerated alternative to ASBL in managing complex PSSA BSI.

G-CSF as a potential early biomarker for diagnosis of bloodstream infection.

BACKGROUND: Cytokines play an important role in bacterial infection, and thus, we aim to find out cytokines that may be diagnostically significant in early stage of bacterial bloodstream infection. METHODS: Mice models infected with Staphylococcus aureus and Klebsiella pneumoniae were established. Then dynamic changes of nine serum cytokines were monitored within 48 hours after the infection. Cytokines with significant differences between the infected groups and control group were further analyzed. Clinical samples of patients who were suspected of bloodstream infection were collected. Then the diagnostic efficiency of screened cytokines was determined with receiver operating characteristic curve analysis. RESULTS: As for mice models infected by Staphylococcus aureus and Klebsiella pneumoniae, six cytokines including IL-1ß, IL-6, IL-12p70, G-CSF, IFN-γ, and TNF-α were significantly different (P < .05) between two bacterial infected groups. As for clinical samples, three cytokines including IL-6, IL-12p70, and G-CSF showed significant differences between infection group (Staphylococcus aureus and Klebsiella pneumonia group) and negative control group. With the area under curve of 0.7350 and 0.6431 for G-CSF and IL-6, respectively, these two cytokines were significantly different between Staphylococcus aureus and Klebsiella pneumoniae infection groups. Combination of G-CSF and IL-6 could improve the AUC to 0.8136. CONCLUSIONS: G-CSF cannot only identify bacterial bloodstream infection, but can also distinguish the infection of Staphylococcus aureus from Klebsiella pneumoniae. Further investigation should be performed concerning the diagnostic efficiency of G-CSF in diagnosing different types of bacterial bloodstream infection.

Infectious diseases specialist consultation in Staphylococcus lugdunensis bacteremia.

BACKGROUND: Commensal coagulase negative Staphylococcus lugdunensis may cause severe bacteremia (SLB) and complications. Treatment of SLB is not fully established and we wanted to evaluate if infectious diseases specialist consultation (IDSC) would improve management and prognosis. METHODS: Multicenter retrospective study of SLB patients followed for 1 year. Patients were stratified according to bedside (formal), telephone (informal) or lack of IDSC within 7 days of SLB diagnosis. RESULTS: Altogether, 104 SLB patients were identified: 24% received formal bedside and 52% informal telephone IDSC whereas 24% were managed without any IDSC. No differences in demographics, underlying conditions or severity of illness were observed between the groups. Patients with bedside IDSC, compared to telephone IDSC or lack of IDSC, had transthoracic echocardiography more often performed (odds ratio [OR] 4.00; 95% confidence interval [CI] 1.31-12.2; p = 0.012) and (OR 16.0; 95% CI, 4.00-63.9; P<0.001). Bedside IDSC was associated with more deep infections diagnosed compared to telephone IDSC (OR, 7.44; 95% CI, 2.58-21.4; p<0.001) or lack of IDSC (OR, 9.56; 95% CI, 2.43-37.7; p = 0.001). The overall mortality was 7%, 10% and 17% at 28 days, 90 days and 1 year, respectively. Considering all prognostic parameters, patients with IDSC, compared to lack of IDSC, had lower 90 days and 1 year mortality (OR, 0.11; 95% CI, 0.02-0.51; p = 0.005) and (OR, 0.22; 95% CI, 0.07-0.67; p = 0.007). CONCLUSION: IDSC may improve management and outcome of Staphylococcus lugdunensis bacteremia.

Increased Risk of Thrombocytopenia and Death in Patients with Bacteremia Caused by High Alpha Toxin-Producing Methicillin-Resistant Staphylococcus aureus.

Alpha toxin (Hla) is a major virulence factor of Staphylococcus aureus that targets platelets but clinical data on Hla pathogenesis in bacteremia (SAB) is limited. We examined the link between in vitro Hla activity and outcome. Study isolates obtained from 100 patients with SAB (50 survivors; 50 non-survivors) were assessed for in vitro Hla production by Western immunoblotting in a subset of isolates and Hla activity by hemolysis assay in all isolates. Relevant demographics, laboratory and clinical data were extracted from patients' medical records to correlate Hla activity of the infecting isolates with outcome. Hla production strongly correlated with hemolytic activity (rs = 0.93) in vitro. A trend towards higher hemolytic activity was observed for MRSA compared to MSSA and with high-risk source infection. Significantly higher hemolytic activity was noted for MRSA strains isolated from patients who developed thrombocytopenia (median 52.48 vs. 16.55 HU/mL in normal platelet count, p = 0.012) and from non survivors (median 30.96 vs. 14.87 HU/mL in survivors, p = 0.014) but hemolytic activity of MSSA strains did not differ between patient groups. In vitro Hla activity of MRSA strains obtained from patients with bacteremia is significantly associated with increased risk for thrombocytopenia and death which supports future studies to evaluate feasibility of bedside phenotyping and therapeutic targeting.

Cefazolin versus cloxacillin as definitive antibiotic therapy for methicillin-susceptible Staphylococcus aureus spinal epidural abscess: a retrospective cohort study.

OBJECTIVES: We compared the effectiveness of cefazolin and cloxacillin as definitive antibiotic therapy for methicillin-susceptible Staphylococcus aureus (MSSA) spinal epidural abscess (SEA). METHODS: This retrospective cohort study included patients with MSSA SEA from two academic hospitals in Hamilton, Ontario, Canada, between 2014 and 2020. Patients treated with cefazolin were compared to those treated with cloxacillin. Co-primary outcomes included 90-day mortality, antibiotic failure, adverse reactions and recurrence. Inverse probability of treatment weighting using propensity scores was used to balance important prognostic factors and to estimate an adjusted risk difference. RESULTS: Of 98 patients with MSSA SEA, 50 and 48 patients were treated with cefazolin and cloxacillin, respectively. Mortality at 90 days was 8% and 13% in the cefazolin and cloxacillin groups, respectively (P = 0.52). The antibiotic failure rate was 12% and 19% in the cefazolin and cloxacillin groups, respectively (P = 0.41). The serious adverse reactions rate was 0% and 4% in the cefazolin and cloxacillin groups, respectively (P = 0.24). The recurrence rate was 2% and 8% in the cefazolin and cloxacillin groups, respectively (P = 0.20). The adjusted risk difference for mortality at 90 days was -1% [95% confidence interval (CI) -10% to 8%] favouring cefazolin. The adjusted risk differences for antibiotic failure, adverse reactions and recurrence were 1% (95% CI -12% to 14%), -5% (95% CI -11% to 2%) and -18% (-36% to -1%) respectively. CONCLUSION: Cefazolin is likely as effective as an antistaphylococcal penicillin and may be considered as a first-line treatment for MSSA SEA.

Clinical impact of implementation of rapid diagnostic testing of blood cultures with Staphylococcus aureus on patient outcomes.

Rapid diagnostic testing in microbiology labs shortens the time to identification of bacteria in blood cultures. Cepheid® GeneXpert® MRSA/SA PCR can be used to distinguish MRSA and MSSA from non-Staphylococcus aureus organisms in blood cultures. This study aims to determine if implementation of MRSA/SA PCR for blood culture pathogen identification, plus daily antimicrobial stewardship intervention, can reduce time to appropriate therapy, vancomycin duration, 30 day mortality, and 90 day recurrence in veterans. A total of 113 patients in the pre-implementation cohort and 73 patients in the post-implementation cohort were evaluated. Time to appropriate therapy was decreased from 49.8 (pre-implementation) to 20.6 (post-implementation) hours. There was a numerically shorter median duration of vancomycin therapy in the post-implementation group. There was no difference in 30 day mortality or 90 day recurrence between groups. Use of MRSA/SA PCR can improve antimicrobial use when combined with once-daily antimicrobial stewardship review.