Clinical management of Staphylococcus aureus bacteremia: a review

Adherence to a care bundle for Staphylococcus aureus bacteraemia: A retrospective cohort study

BACKGROUND

Staphylococcus aureus bacteraemia is associated with high hospital mortality. Improvements in outcome have been described with standardised bundles of care.

OBJECTIVES

To study the adherence of a standardised bundle of care (BOC) recommendations using a consultation pro forma, for all patients admitted with S. aureus bacteraemia to Groote Schuur Hospital over a year. The study further aimed to describe the 90-day mortality in these patients and to assess for an association between adherence to the bundle of care and outcome.

METHOD

A retrospective audit of all unsolicited infectious disease consultations for patients with S. aureus bacteraemia admitted to Groote Schuur Hospital during 2018. Adherence to recommendations of a standard bundle of care was audited.

RESULTS

A total of 86 patients were included in the study: 61 (71%) with hospital-associated infection and 25 (29%) with community-associated infection. Over 80% of adherence to treatment recommendations was achieved regarding antibiotic (including vancomycin) usage, source control and use of echocardiography as required. In-hospital mortality was 16%, while the overall 90-day mortality was 18%, with only age as an independent predictor of mortality. No association between adherence to the bundle of care and outcome was found.

CONCLUSION

Adherence to a simple, structured bundle of care was good when using standardised pro forma as communication tools for advice and a structured antibiotic chart for vancomycin administration. Although adherence was not associated with outcome, the overall mortality for S. aureus bacteraemia was improving in the institution under study.

CONTRIBUTION

Our findings support feasibility and ongoing use of bundles of care for S. aureus bacteraemia in similar settings.

The effect of duration of therapy for treatment of Staphylococcus aureus blood stream infection: an application of cloning to deal with immortal-time bias in an analysis of data from a cohort study (BSI-FOO)

OBJECTIVE

To estimate the effect of treatment duration on in-hospital mortality in patients with Staphylococcus aureus blood stream infection and demonstrate the biases that can arise when immortal-time bias is ignored.

EXPOSURE

We compared three treatment strategies: short therapy (<10 days), intermediate (10-18 days) and long (>18 days).

MAIN OUTCOME MEASURES

Twenty-eight-day all-cause in-hospital mortality.

METHODS

Using data from the BSI-FOO study, we implemented an approach proposed by Hernán to overcome confounding and immortal-time biases. The first stage is to clone all participants, so that each participant is assigned to each treatment strategy. Second, observations are censored when their data becomes inconsistent with their assigned strategy. Finally, inverse-probability weights are applied to adjust for potential selection. We compared our results to a naïve approach where immortal-time bias is ignored.

RESULTS

Of the 1903 participants in BSI-FOO, 587 were eligible and included in the analysis. After cloning, the weighted estimates of hazard ratio of mortality for short versus long therapy was 1.74 (95% CI 1.36, 2.24) and for intermediate versus long therapy was 1.09 (0.98, 1.22). In the naïve approach, the hazard ratios with reference to the long therapy group are 37.4 (95% CI 18.9 to 74.4) in the short therapy group and 4.1 (95% CI 1.9 to 8.9) in the intermediate therapy group.

CONCLUSIONS

Our findings suggest that duration of therapy >18 days is beneficial with respect to 28-day in-hospital mortality, however, there remains uncertainty around the efficacy of reducing duration of treatment to 10-18 days.

The Novel Oxazolidinone TBI-223 Is Effective in Three Preclinical Mouse Models of Methicillin-Resistant Staphylococcus aureus Infection

Staphylococcus aureus is an important cause of various infections in humans, including bacteremia, skin and soft tissue infections, and infections associated with implanted medical devices. The emergence of hospital- and community-acquired methicillin-resistant Staphylococcus aureus (MRSA) underscores the urgent and unmet need to develop novel, safe, and effective antibiotics against these multidrug-resistant clinical isolates. Oxazolidinone antibiotics such as linezolid have excellent oral bioavailability and provide coverage against MRSA infections. However, their widespread and long-term use is often limited by adverse effects, especially myelosuppression. TBI-223 is a novel oxazolidinone with potentially reduced myelosuppression, compared to linezolid, but its efficacy against MRSA infections is unknown. Therefore, the preclinical efficacy of TBI-223 (80 and 160 mg/kg twice daily) was compared with that of linezolid (40 and 80 mg/kg twice daily) and sham treatment in mouse models of MRSA bacteremia, skin wound infection, and orthopedic-implant-associated infection. The dosage was selected based on mouse pharmacokinetic analysis of both linezolid and TBI-223, as well as measurement of the MICs. In all three models, TBI-223 and linezolid had comparable dose-dependent efficacies in reducing bacterial burden and disease severity, compared with sham-treated control mice. Taken together, these findings indicate that TBI-223 represents a novel oxazolidinone antibiotic that may provide an additional option against MRSA infections. Future studies in larger animal models and clinical trials are warranted to translate these findings to humans. IMPORTANCE Staphylococcus aureus is the predominant cause of bloodstream, skin, and bone infections in humans. Resistance to commonly used antibiotics is a growing concern, making it more difficult to treat staphylococcal infections. Use of the oxazolidinone antibiotic linezolid against resistant strains is hindered by high rates of adverse reactions during prolonged therapy. Here, a new oxazolidinone named TBI-223 was tested against S. aureus in three mouse models of infection, i.e., bloodstream infection, skin infection, and bone infection. We found that TBI-223 was as effective as linezolid in these three models. Previous data suggest that TBI-223 has a better safety profile than linezolid. Taken together, these findings indicate that this new agent may provide an additional option against MRSA infections. Future studies in larger animal models and clinical trials are warranted to translate these findings to humans.

Proline Transport and Growth Changes in Proline Transport Mutants of Staphylococcus aureus

Staphylococcus aureus is a major cause of skin/soft tissue infections and more serious infections in humans. The species usually requires the importation of proline to be able to survive. Previous work has shown that single mutations in genes that encode for proline transporters affect the ability of S. aureus to survive in vitro and in vivo. To better understand proline transport in S. aureus, double and triple gene mutant strains were created that targeted the opuD, proP, and putP genes. Single gene mutants had some effect on proline transport, whereas double mutants exhibited significantly lower proline transport. An opuD prop putP triple gene mutant displayed the lowest proline transport under low- and high-affinity conditions. To assess growth differences caused by the mutations, the same mutants were grown in brain heart infusion (BHI) broth and defined staphylococcal medium (DSM) with various concentrations of proline. The triple mutant did not grow in DSM with a low concentration of proline and grew poorly in both DSM with a high proline concentration and BHI broth. These results show that S. aureus has multiple mechanisms to import proline into the cell and knocking out three of the main proline transporters significantly hinders S. aureus growth.

Staphylococcus aureus bacteremia mortality across country income groups: A secondary analysis of a systematic review

OBJECTIVES

Staphylococcus aureus bacteremia (SAB) is a common infection worldwide. We compared SAB mortality in low- and middle-income countries (LMIC) versus high-income countries (HIC) in a meta-analysis.

METHODS

We searched MEDLINE, Embase, and Cochrane Database of Systematic Reviews from 1991-2021 and included observational, single-country studies on patients with positive blood cultures for S. aureus. The main outcome was the proportion of patients with SAB who died in the hospital. A generalized linear mixed random-effects model was used to pool estimates, and a meta-regression was used to adjust for study-level characteristics.

RESULTS

A total of 332 studies involving 517,671 patients in 39 countries were included. No study was conducted in a low-income country. Only 33 (10%) studies were performed in middle-income countries (MIC), which described 6,216 patients. The pooled in-hospital mortality was 32.4% (95% confidence interval [CI] 27.2%-38.2%, T2 = 0.3063) in MIC and 22.3% (95% CI 20.1%-24.6%, T2 = 0.3257) in HIC. In a meta-regression model, MIC had higher in-hospital mortality (adjusted odds ratio 1.37, 95% CI 1.11-1.71; P = 0.0042) than HIC.

CONCLUSION

In SAB studies, LMIC are poorly represented. In-hospital mortality was significantly higher in MIC than in HIC. Research should be conducted in LMIC to characterize differences in care processes driving the mortality gap.

Association of Follow-up Blood Cultures With Mortality in Patients With Gram-Negative Bloodstream Infections: A Systematic Review and Meta-analysis

Importance

Obtaining follow-up blood cultures (FUBCs) in patients with Staphylococcus aureus bloodstream infection (BSI) is standard practice, although its utility in patients with gram-negative bacterial BSI (GN-BSI) is unclear.

Objective

To examine whether obtaining FUBCs is associated with decreased mortality (key question [KQ] 1) and whether positive vs negative FUBCs are associated with increased mortality (KQ2).

Data Sources

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science, and gray literature were searched from inception to March 11, 2022.

Study Selection

Two investigators used predefined eligibility criteria to independently screen titles, abstracts, and relevant full texts. Randomized clinical trials or observational studies that matched or statistically adjusted for differences in, at minimum, level of acute illness between patients in the intervention (eg, FUBCs obtained) and control (eg, FUBCs not obtained) groups were included in primary analyses. Articles published in languages other than English were excluded.

Data Extraction and Synthesis

Data abstraction and quality assessments were performed by one investigator and verified by a second investigator. Risk of bias was assessed with the Newcastle-Ottawa Scale. Effect sizes were pooled using random-effects models. The study followed the Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline.

Main Outcomes and Measures

Mortality before hospital discharge or up to 30 days from the index blood culture.

Results

From 3495 studies, 15 were included (all nonrandomized). In the 5 studies (n = 4378 patients) that met criteria for the KQ1 primary analysis, obtaining FUBCs was associated with decreased mortality (hazard ratio, 0.56; 95% CI, 0.45-0.71). For KQ2, 2 studies met criteria for the primary analysis (ie, matched or statistically adjusted for differences in patients with positive vs negative FUBCs), so an exploratory meta-analysis of all 9 studies that investigated KQ2 (n = 3243 patients) was performed. Positive FUBCs were associated with increased mortality relative to negative blood cultures (odds ratio, 2.27; 95% CI, 1.54-3.34). Limitations of the literature included a lack of randomized studies and few patient subgroup analyses.

Conclusions and Relevance

In this systematic review and meta-analysis, obtaining FUBCs in patients with GN-BSI was associated with decreased mortality. The benefit of FUBCs may stem from identification of patients with positive FUBCs, which was a poor prognostic marker.

Current clinical practice in antibiotic treatment of Staphylococcus aureus bacteraemia: results from a survey in five European countries

OBJECTIVES

To determine clinical practice variation and identify knowledge gaps in antibiotic treatment of Staphylococcus aureus bacteraemia (SAB).

METHODS

A web-based survey with questions addressing antibiotic treatment of SAB was distributed through the ESGAP network among infectious disease specialists, clinical microbiologists and internists in Croatia, France, Greece, the Netherlands and the UK between July 2021 and November 2021.

RESULTS

A total number of 1687 respondents opened the survey link, of whom 677 (40%) answered at least one question. For MSSA and MRSA bacteraemia, 98% and 94% preferred initial monotherapy, respectively. In patients with SAB and non-removable infected prosthetic material, between 80% and 90% would use rifampicin as part of the treatment. For bone and joint infections, 65%-77% of respondents would consider oral step-down therapy, but for endovascular infections only 12%-32% would. Respondents recommended widely varying treatment durations for SAB with different foci of infection. Overall, 48% stated they used 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG-PET/CT) to guide antibiotic treatment duration. Persistent bacteraemia was the only risk factor for complicated SAB that would prompt a majority to extend treatment from 2 to 4-6 weeks.

CONCLUSIONS

This survey in five European countries shows considerable clinical practice variation between and within countries in the antibiotic management of SAB, in particular regarding oral step-down therapy, choice of oral antibiotic agents, treatment duration and use of 18F-FDG-PET/CT. Physicians use varying criteria for treatment decisions, as evidence from clinical trials is often lacking. These areas of practice variation could be used to prioritize future studies for further improvement of SAB care.

Prevalence and Characterization of the Cefazolin Inoculum Effect in North American Methicillin-Susceptible Staphylococcus aureus Isolates

Antistaphylococcal penicillins and cefazolin remain the primary treatments for infections with methicillin-susceptible Staphylococcus aureus (MSSA). The cefazolin inoculum effect (CzIE) causes the cefazolin MIC to be elevated in proportion to the number of bacteria in the inoculum. The objective of this multicenter study was to evaluate the prevalence of the CzIE in North American MSSA isolates. Clinical MSSA isolates from six microbiology laboratories in the United States and one microbiology laboratory in Canada were screened for the CzIE by broth microdilution at a standard inoculum (~5 × 10⁵ CFU/mL) and a high inoculum (~5 × 10⁷ CFU/mL). Genome sequencing was performed to further characterize the MSSA isolates. The CzIE was present in 57/305 (18.6%) MSSA isolates, ranging from 0% to 27.9% across study sites. More of the CzIE-positive isolates (29.8%) had standard inoculum cefazolin MICs of 1.0 μg/mL than the CzIE-negative isolates did (3.2%) (P < 0.0001). Conversely, more CzIE-negative isolates (39.5%) had standard inoculum MICs of 0.25 μg/mL than the CzIE positive isolates did (5.3%) (P < 0.0001). The most common BlaZ β-lactamase types found in the CzIE-positive strains were type C (53.7%) and type A (44.4%). ST8 and ST30 were the most common sequence types among CzIE-positive isolates and correlated with BlaZ type C and A, respectively. The CzIE was present in up to a quarter of clinical MSSA isolates from North American clinical laboratories. Further studies to determine the impact of the presence of the CzIE on clinical outcomes are needed.

Decreased quality of care for Staphylococcus aureus bacteremia during the COVID-19 pandemic

Objectives

Staphylococcus aureus bacteremia (SAB) is one of the most frequent bloodstream infections. High mortality of SAB can be significantly reduced by regular infectious disease (ID) consultations and appropriate clinical management. Because the pandemic of coronavirus disease 2019 (COVID-19) has had a negative impact on hospital ID service, it can be assumed that it has also led to decreased quality of care for SAB patients.

Methods

This study enrolled all (n = 68) patients with proven SAB who were hospitalized in Military University Hospital, Prague, in 2019 and 2020 and the quality of care indicators for SAB patients were compared.

Results

A total of 33 and 35 patients with SAB were hospitalized in our hospital in 2019 and 2020, respectively. The significant difference between the pandemic year 2020 and year 2019 was in ID consultations performed (74% vs. 100%; p = 0.002) and fulfilment of all quality of care indicators (66% vs. 93%; p = 0.012). Next, higher in-hospital mortality was observed in 2020 than in 2019 (6% vs. 23%; p = 0.085). There was no significant difference in the percentages of patients with performed echocardiographic examinations (66% vs. 83%; p = 0.156) and collected follow-up blood cultures (85% vs. 94%; p = 0.428). In addition, there was no difference between the two years in the adequate antibiotic therapy, sources, and bacterial origin of SAB.

Conclusions

The quality of care of SAB patients significantly decreased during the COVID-19 pandemic in our institution.

Comparison of Sequential Dalbavancin to Standard-of-Care Treatment for Staphylococcus aureus Bloodstream Infections

Background

Dalbavancin (DAL) is a long-acting lipoglycopeptide with activity against Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). This study investigates DAL as sequential therapy in S. aureus bloodstream infections (BSIs).

Methods

We conducted a retrospective cohort study from 2014 to 2021 comparing sequential DAL with standard-of-care therapy (SoC) for S. aureus BSI. The primary outcome was 90-day clinical failure (90-day all-cause mortality or 90-day recurrence). Secondary outcomes were incidence of acute kidney injury, creatinine phosphokinase elevations, catheter-related thrombosis, and hospital-acquired infections. Analyses were adjusted using inverse probability of treatment weighting (IPTW).

Results

Overall, 225 patients (45 DAL, 180 SoC) were included. DAL patients had a higher incidence of community-acquired infection and persons who use drugs; SoC patients had more comorbidities and a longer duration of bacteremia. MRSA incidence was similar between the DAL and SoC groups. The median length of stay was 16 days among DAL recipients compared with 24 days among SoC recipients. Central catheter placement was 17.8% compared with 57.2% in the SoC group. Ninety-day clinical failure occurred in 13.3% and 18.3% of participants in the DAL and SOC groups, respectively. In IPTW-adjusted analysis, sequential DAL was not associated with 90-day clinical failure (adjusted odds ratio, 0.94; 95% CI, 0.333–2.32).

Conclusions

This study provides preliminary evidence that select patients with S. aureus BSI treated with sequential DAL have similar clinical failure rates, with significant reductions in catheter placement and hospital length of stay compared with SoC. Further prospective evaluation is needed.

TLR2, TLR4, and NLRP3 mediated the balance between host immune-driven resistance and tolerance in Staphylococcus aureus-infected mice

Staphylococcus aureus (S. aureus) is a gram-positive pathogen that can cause infectious diseases in mammals. S. aureus-induced host innate immune responses have a relationship with Toll-like receptor 2 (TLR2), TLR4, and Nod-like receptor pyrin domain-containing protein 3 (NLRP3). However, the detailed roles of TLR2, TLR4, and NLRP3 in regulating the host inflammatory response to S. aureus infection remain unclear. Our data indicated that the S. aureus-induced mortality was aggravated by deficiency of TLR2, TLR4, and NLRP3 in mice. In the subsequent experiment, we found that during S. aureus infection, the roles of TLR2, TLR4, and NLRP3 seemed to be different at multiple timepoints. The deficiency of TLR2, TLR4, or NLRP3 attenuated the expression of High-mobility group box protein 1 (HMGB1) and Hyaluronic acid-binding protein 2 (HABP2), which is accompanied by decreased proinflammatory cytokine (TNF-α), chemokine (RANTES), and anti-inflammatory cytokine (IL-10) production in lungs and serum at 3 h and 6 h post-infection. However, with S. aureus infection prolonged (24 h post-infection), the trend was diametrically opposite. The results showed that deficiency of TLR2, TLR4, or NLRP3 aggravated HABP2 and HMGB1 expression, which is accompanied by enhanced proinflammatory cytokine (TNF-α), chemokine (RANTES), and anti-inflammatory cytokine (IL-10) production in lungs and serum. These results were consistent with the data observed in S. aureus-infected bone marrow-derived macrophages (BMDMs). All these results suggested that during S. aureus infection, TLR2, TLR4, and NLRP3 has time-dependent effect in regulating the balance between immune-driven resistance and tolerance.

Determination of plasma protein binding of dalbavancin

OBJECTIVES

Dalbavancin is a lipoglycopeptide with a long half-life, making it a promising treatment for infections requiring prolonged therapy, such as complicated Staphylococcus aureus bacteraemia. Free drug concentration is a critical consideration with prolonged treatment, since free concentration-time profiles may best correlate with therapeutic effect. In support of future clinical trials, we aimed to develop a reliable and reproducible assay for measuring free dalbavancin concentrations.

METHODS

The ultracentrifugation technique was used to determine free dalbavancin concentrations in plasma at two concentrations (50 and 200 mg/L) in duplicate. Centrifuge tubes and pipette tips were treated for 24 h before use with Tween 80 to assess adsorption. Dalbavancin concentrations were analysed from the plasma samples (total) and middle layer samples (free) by LC/MS/MS with isotopically labelled internal standard. Warfarin served as a positive control with known high protein binding.

RESULTS

Measurement of free dalbavancin was sensitive to adsorption onto plastic. Treatment of tubes and pipette tips with ≥2% Tween 80 effectively prevented drug loss during protein binding experiments. By the ultracentrifugation method, dalbavancin's protein binding was estimated to be approximately 99%.

CONCLUSIONS

Dalbavancin has very high protein binding. Given dalbavancin's high protein binding, accurate measurement of free dalbavancin concentrations should be a key consideration in future exposure-response studies, especially clinical trials. Future investigations should confirm if the active fraction is best predicted by the free or total fraction.

Point-of-Care Ultrasound (POCUS) as an Extension of the Physical Examination in Patients with Bacteremia or Candidemia

Background: In general, transthoracic echocardiography (TTE) is the first diagnostic test used for patients with bacteremia or candidemia and clinical signs of Infective Endocarditis (IE). Point-of-care ultrasound (POCUS) may be used in addition to physical examination for the detection of structural heart disease and valve abnormalities. Objective: To determine the diagnostic accuracy of POCUS for the detection of signs suggestive of IE, including vegetation, valvular regurgitation, structural heart disease, hepatomegaly, splenomegaly and septic embolisms, in patients with bacteremia or candidemia. Design: Observational, cross-sectional, multicenter study using convenience sampling. Setting: Six Spanish academic hospitals. Patients: Adult patients with bacteremia or candidemia between 1 February 2018 and 31 December 2020. Measurements: The reference test, to evaluate vegetation, valvular regurgitation and structural heart disease, was transesophageal echocardiography (TEE). For patients who did not undergo TEE, transthoracic echocardiography (TTE) was considered the reference test. POCUS was performed by internists, while conventional echocardiography procedures were performed by cardiologists. Results: In 258 patients, for the detection of valvular vegetation, POCUS had sensitivity, specificity, and positive and negative predictive values of 77%, 94%, 82% and 92%, respectively. For valvular regurgitation (more than mild), sensitivity was ≥76% and specificity ≥85%. Sensitivity values for the detection of hepatomegaly and splenomegaly were 92% and 92%, respectively, while those for specificity were 96% and 98%. Conclusion: POCUS could be a valuable tool, as a complement to physical examination, at the hospital bedside for patients with bacteremia or candidemia, helping to identify signs suggestive of IE.

Hospital-Wide Protocol Significantly Improved Appropriate Management of Patients with Staphylococcus aureus Bloodstream Infection

Background:Staphylococcus aureus bloodstream infection (SA-BSI) causes morbidity and mortality. We established a management protocol for patients with SA-BSI aimed at improving quality of care and patient outcomes. Methods: A retrospective pre−post intervention study was conducted at Maharaj Nakorn Chiang Mai Hospital from 1 October 2019 to 30 September 2020 in the pre-intervention period and from 1 November 2020 to 31 October 2021 in the post-intervention period. Results: Of the 169 patients enrolled, 88 were in the pre-intervention and 81 were in the post-intervention periods. There were similar demographic characteristics between the two periods. In the post-intervention period, evaluations for metastatic infections were performed more frequently, e.g., echocardiography (70.5% vs. 91.4%, p = 0.001). The appropriateness of antibiotic prescription was higher in the post-intervention period (42% vs. 81.5%, p < 0.001). The factors associated with the appropriateness of antibiotic prescription were ID consultation (OR 15.5; 95% CI = 5.9−40.8, p < 0.001), being in the post-intervention period (OR 9.4; 95% CI: 3.5−25.1, p < 0.001), and thorough investigations for metastatic infection foci (OR 7.2; 95% CI 2.1−25.2, p = 0.002). However, the 90-day mortality was not different (34.1% and 27.2% in the pre- and post-intervention periods, respectively). The factors associated with mortality from the multivariate analysis were the presence of alteration of consciousness (OR 11.24; 95% CI: 3.96−31.92, p < 0.001), having a malignancy (OR 6.64; 95% CI: 1.83−24.00, p = 0.004), hypoalbuminemia (OR 5.23; 95% CI: 1.71−16.02, p = 0.004), and having a respiratory tract infection (OR 5.07; 95% CI: 1.53−16.84, p = 0.008). Source control was the only factor that reduced the risk of death (OR 0.08; 95% CI: 0.01−0.53, p = 0.009). Conclusion: One-third of patients died. Hospital-wide protocol implementation significantly improved the quality of care. However, the mortality rate did not decrease.

Star-Peptide Polymers are Multi-Drug-Resistant Gram-Positive Bacteria Killers

Antibiotic resistance in bacteria, especially Gram-positive bacteria like Staphylococcus aureus, is gaining considerable momentum worldwide and unless checked will pose a global health crisis. With few new antibiotics coming on the market, there is a need for novel antimicrobial materials that target and kill multi-drug-resistant (MDR) Gram-positive pathogens like methicillin-resistant Staphylococcus aureus (MRSA). In this study, using a novel mixed-bacteria antimicrobial assay, we show that the star-peptide polymers preferentially target and kill Gram-positive pathogens including MRSA. A major effect on the activity of the star-peptide polymer was structure, with an eight-armed structure inducing the greatest bactericidal activity. The different star-peptide polymer structures were found to induce different mechanisms of bacterial death both in vitro and in vivo. These results highlight the potential utility of peptide/polymers to fabricate materials for therapeutic development against MDR Gram-positive bacterial infections.

Optimal Sampling Strategy and Threshold of Serum Vancomycin Concentration in Elderly Japanese Patients Undergoing High-Flux Hemodialysis

BACKGROUND

The optimal sampling points and thresholds for initial serum vancomycin (VCM) concentrations have not been determined in hemodialysis (HD) patients. To clarify this, multiple blood tests were performed, and the correlations between VCM concentrations at several sampling points and the area under the concentration-time curve for 24 hours (AUC24h) were analyzed.

METHODS

A single-center, prospective observational study was conducted. Patients with end-stage renal failure who received VCM treatment while undergoing chronic maintenance HD were enrolled in this study. HD was performed using a high-flux membrane as the dialyzer. After VCM administration, 7 points were sampled between the first and second HD. The AUC24h after the end of the first HD (AUC0-24) and that before the end of the second HD (AUC24-48) were calculated using the linear trapezoidal method. Correlation analysis and simple regression analysis between AUC24h and serum concentrations were performed at each sampling point.

RESULTS

Nine patients were evaluated. Strong correlations were found between AUC24-48 and serum concentrations at 24 hours after the initiation of VCM treatment following the first HD (C24h, R = 0.983 and P < 0.001), between AUC0-24 and C24h (R = 0.967 and P < 0.001), and between AUC24-48 and serum concentration just before the second HD (Cpre(HD2), R = 0.965 and P < 0.001). Regression equations with high coefficients of determination (R2 > 0.9) were obtained, and a C24h of ≥18.0 mg/L and a Cpre(HD2) of ≥16.5 mg/L were required to achieve an AUC24-48 value of ≥400 mg·h/L. In addition, a C24h of ≤23.3 mg/L was estimated to satisfy the AUC0-24 range of ≤600 mg·h/L.

CONCLUSIONS

C24h and Cpre(HD2) are optimal sampling points for predicting VCM-AUC24h in HD patients.

Potent Activity of Ertapenem Plus Cefazolin Within Staphylococcal Biofilms: A Contributing Factor in the Treatment of Methicillin-Susceptible Staphylococcus aureus Endocarditis

Background

Besides antistaphylococcal beta-lactams and source control, there are limited validated antimicrobial salvage options in patients with prolonged methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia, including infective endocarditis (IE).

Methods

MSSA IE cases treated with ertapenem (ETP) plus cefazolin (CZ) were compared with matched IE cases treated with standard beta-lactam monotherapy. The bactericidal activity of ETP plus CZ was also compared with nafcillin (NAF), CZ, and ETP alone using an in vitro MSSA biofilm model.

Results

The median duration of bacteremia experienced by patients (n = 12) while on CZ or NAF was 4 days (range 1-16 days) compared with 1 day (range 1-3 days) for patients (n = 5) treated with ETP + CZ (P = .01, Mann-Whitney U test). Cefazolin and NAF alone or in combination did not achieve biofilm eradication at clinically relevant concentrations. However, the addition of ETP to CZ led to bactericidal eradication within biofilms at standard dosing.

Conclusions

Ertapenem reduces CZ concentrations required to eradicate MSSA biofilms to those achievable in vivo by standard dosing, translating into shorter bacteremia duration in patients with MSSA endocarditis. Larger studies are needed to investigate ETP plus CZ therapy in the treatment of biofilm-related MSSA infections such as endocarditis.

Effect of First Trough Vancomycin Concentration on the Occurrence of AKI in Critically Ill Patients: A Retrospective Study of the MIMIC-IV Database

Background

Vancomycin can effectively inhibit Gram-positive cocci and is widely used in critically ill patients. This study utilized a large public database to explore the effect of patients' first vancomycin trough concentration (FVTC) on the occurrence of acute kidney injury (AKI) and mortality after receiving vancomycin treatment in intensive care unit (ICU).

Methods

Critically ill patients who used vancomycin in the Medical Information Mart for Intensive Care (MIMIC) IV have been retrospectively studied. The outcomes included the occurrence of AKI during the use of vancomycin or within 72 h of withdrawal, ICU mortality and hospital mortality. Restricted cubic splines (RCS) were used to analyze the linear relationship between FVTC and the outcomes. Multivariate logistic/Cox regression analysis was used to analyze the association between patient's FVTC and the occurrence of AKI, ICU mortality, and in-hospital mortality.

Results

The study ultimately included 3,917 patients from the MIMIC-IV database who had been treated with vancomycin for more than 48 h. First of all, the RCS proved the linear relationship between FVTC and the outcomes. After controlling for all covariates as confounders in logistic/Cox regression, FVTC was a risk factor with the occurrence of AKI (OR: 1.02; 95% CI: 1.01–1.04), ICU mortality (HR: 1.02; 95% CI: 1.01–1.03), and in-hospital mortality (HR: 1.02; 95% CI: 1.01–1.03). Moreover, patients were divided into four groups in the light of the FVTC value: group1 ≤ 10 mg/L, 10 <group 2 ≤ 15 mg/L, 15 <group 3 ≤ 20 mg/L, group4 > 20 mg/L. Categorical variables indicated that group 3 and group 4 had a significant relationship on the occurrence of AKI [group 3: (OR: 1.36; 95% CI: 1.02–1.81); group 4: (OR: 1.76; 95% CI: 1.32–2.35)] and ICU mortality [group 3: (HR: 1.47; 95% CI: 1.03–2.09); group 4: (HR: 1.87; 95% CI: 1.33–2.62)], compared to group 1, while group 4 had a significant effect on in-hospital mortality (HR: 1.48; 95% CI: 1.15–1.91).

Conclusions

FVTC is associated with the occurrence of AKI and increased ICU and in-hospital mortality in critically ill patients. Therefore, in clinical practice, patients in intensive care settings receiving vancomycin should be closely monitored for FVTC to prevent drug-related nephrotoxicity and reduce patient mortality.

What Is the Optimal Follow-up Length for Mortality in Staphylococcus aureus Bacteremia? Observations From a Systematic Review of Attributable Mortality

Background

Deaths following Staphylococcus aureus bacteremia (SAB) may be related or unrelated to the infection. In SAB therapeutics research, the length of follow-up should be optimized to capture most attributable deaths and minimize nonattributable deaths. We performed a secondary analysis of a systematic review to describe attributable mortality in SAB over time.

Methods

We systematically searched Medline, Embase, and Cochrane Database of Systematic Reviews from 1 January 1991 to 7 May 2021 for human observational studies of SAB. To be included in this secondary analysis, the study must have reported attributable mortality. Two reviewers extracted study data and assessed risk of bias independently. Pooling of study estimates was not performed due to heterogeneity in the definition of attributable deaths.

Results

Twenty-four observational cohort studies were included. The median proportion of all-cause deaths that were attributable to SAB was 77% (interquartile range [IQR], 72%–89%) at 1 month and 62% (IQR, 58%–75%) at 3 months. At 1 year, this proportion was 57% in 1 study. In 2 studies that described the rate of increase in mortality over time, 2-week follow-up captured 68 of 79 (86%) and 48 of 57 (84%) attributable deaths that occurred by 3 months. By comparison, 1-month follow-up captured 54 of 57 (95%) and 56 of 60 (93%) attributable deaths that occurred by 3 months in 2 studies.

Conclusions

The proportion of deaths that are attributable to SAB decreases as follow-up lengthens. Follow-up duration between 1 and 3 months seems optimal if evaluating processes of care that impact SAB mortality.

Clinical Trials Registration

PROSPERO CRD42021253891.

[Diagnosis and treatment of catheter-related bloodstream infection in hemodialysis: 10 years later]

Patients in hemodialysis on central venous catheter as vascular access are at risk of infections. Catheter-related bloodstream infection is one of the most serious catheter-complications in hemodialysis patients. Its clinical and microbiological diagnosis is challenging. The implementation of empiric antibiotic therapy is based on old recommendations proposing the combination of a molecule targeting methicillin-resistant Staphylococcus aureus and a betalactamin active on P. aeruginosa, and also adapting this probabilistic treatment by carrying out a microbiological register on a local scale, which is rarely done. In our hemodialysis center at Bordeaux University Hospital, an analysis of the microorganisms causing all catheter-related bloodstream infection over the period 2018-2020 enabled us to propose, in agreement with the infectious disease specialists, an adapted probabilistic antibiotic therapy protocol. This approach allowed us to observe a low incidence of meticillinoresistance of Staphylococcus. For catheters inserted more than 6 months ago, we observed no Staphylococcus, no multi-resistant Pseudomonas, and only 2% of Enterobacteria resistant to cephalosporins. A frequent updating of the microbiological epidemiology of catheter-related bloodstream infection, in partnership with the infectious diseases team in each hemodialysis center, allowing an adaptation of the probabilistic antibiotic therapy, and seems to have a good feasibility. This strategy might favor the preservation of microbial ecology on an individual and collective scale in maintenance hemodialysis patients.

Efficacy and Safety of Daptomycin versus Vancomycin for Bacteremia Caused by Methicillin-Resistant Staphylococcus aureus with Vancomycin Minimum Inhibitory Concentration > 1 µg/mL: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis compares the efficacy of daptomycin and vancomycin in adult patients with bacteremia by methicillin-resistant Staphylococcus aureus (MRSA) with vancomycin minimum inhibitory concentration (MIC) > 1 µg/mL. We searched the PubMed, Web of Science, Cochrane Library, and ClinicalTrials.gov databases on 12 May 2020. All-cause mortality (primary outcome) and treatment success rates were compared and subgroups stratified by infection source risk level and method of vancomycin susceptibility testing were also analyzed. Seven studies (n = 907 patients) were included in this efficacy analysis. Compared with vancomycin, daptomycin treatment was associated with significantly lower mortality (six studies, odds ratio (OR) 0.53, 95% confidence interval (CI) 0.29−0.98) and higher treatment success (six studies, OR 2.20, 95% CI 1.63−2.96), which was consistent regardless of the vancomycin MIC test method used. For intermediate-risk sources, daptomycin was a factor increasing treatment success compared with vancomycin (OR 4.40, 95% CI 2.06−9.40), and it exhibited a trend toward a higher treatment success rate for high-risk sources. In conclusion, daptomycin should be considered for the treatment of bacteremia caused by MRSA with vancomycin MIC > 1 µg/mL, especially in patients with intermediate- and high-risk bacteremia sources.

Staphylococcus aureus bacteremia mortality: A systematic review and meta-analysis

BACKGROUND

Precise estimates of mortality in Staphylococcus aureus bacteremia (SAB) are important to convey prognosis and guide design of interventional studies.

OBJECTIVE

We performed a systematic review and meta-analysis to estimate the all-cause mortality in SAB and to explore how it changed with time.

DATA SOURCES

MEDLINE, Embase, and Cochrane Database of Systematic Reviews from January 1, 1991 to May 7, 2021.

STUDY ELIGIBILITY CRITERIA

Human observational studies on patients with S. aureus bloodstream infection.

PARTICIPANTS

Patients with a positive blood culture for S. aureus.

METHODS

Two independent reviewers extracted study data and assessed risk of bias using the Newcastle Ottawa Scale. A generalized linear mixed random effects model was used to pool estimates.

RESULTS

A total of 341 studies were included, which described 536,791 patients. From 2011 onwards, the estimated mortality was 10.4% (95% confidence interval (CI) 9.0%-12.1%) at 7 days, 13.3% (95% CI 11.1%-15.8%) at 2 weeks, 18.1% (95% CI 16.3%-20.0%) at 1 month, 27.0% (95% CI 21.5%-33.3%) at 3 months, and 30.2% (95% CI 22.4%-39.3%) at 1 year. In a meta-regression model of 1-month mortality, methicillin-resistant S. aureus (MRSA) had a higher mortality (adjusted odds ratio (aOR) 1.04 95% CI 1.02-1.06 per 10% increase in MRSA proportion), and compared to prior to 2001, more recent time periods had lower mortality (aORs 0.88 [95% CI 0.75-1.03] for 2001 to 2010; 0.82 [95% CI 0.69-0.97] for 2011 onwards).

CONCLUSIONS

SAB mortality has decreased over the last 3 decades. However, more than 1 in 4 patients will die within 3 months and continuous improvement in care remains necessary.

REGISTRATION

PROSPERO CRD42021253891.

Effectiveness and Safety of Ceftriaxone Compared to Standard of Care for Treatment of Bloodstream Infections Due to Methicillin-Susceptible Staphylococcus aureus: A Systematic Review and Meta-Analysis

(1) Background: Ceftriaxone is a potential alternative for the treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infections (BSIs) in acute care and outpatient parenteral antimicrobial therapy (OPAT) settings. We evaluated the effectiveness and safety of ceftriaxone for the treatment of MSSA BSIs. (2) Method: We searched PubMed, Embase, and Cochrane Library from their inception to October 30th 2021. Our outcomes included clinical cure, microbiological cure, 30- and 90-day mortality, 90-day hospital readmission, and adverse drug reactions (ADRs). We compared ceftriaxone against standard of care (SOC) therapy. We used the random-effects model for the meta-analysis, and our estimated effects were reported as odds ratios (ORs) with 95% confidence intervals (CI). (3) Results: Twelve retrospective cohort studies were included, comprising 1037 patients in the ceftriaxone arms and 2088 patients in the SOC arms. The clinical cure rate of the ceftriaxone regimen was not statistically different from SOC: OR 0.65 (95% CI: 0.29-1.45). Ceftriaxone was also not statistically different from SOC in microbiological cure: OR 1.48 (95% CI: 0.29-7.51); 30-day mortality: OR 0.79 (95% CI: 0.14-4.65); 90-day mortality: OR 0.82 (95% CI: 0.38-1.80); 90-day hospital readmission: OR 1.20 (95% CI: 0.92-1.56); and ADRs: OR 0.92 (95% CI: 0.39-2.18). (4) Conclusion: Ceftriaxone could provide an alternative for the treatment of MSSA BSIs in acute care and OPAT settings (except in patients whose BSIs were due to infective endocarditis).

Patients' Experiences With Staphylococcus aureus and Gram-Negative Bacterial Bloodstream Infections: Results From Cognitive Interviews to Inform Assessment of Health-Related Quality of Life

BACKGROUND

We previously conducted a concept elicitation study on the impact of Staphylococcus aureus and gram-negative bacterial bloodstream infections (SAB/GNB) on health-related quality of life (HRQoL) from the patient's perspective and found significant impacts on HRQoL, particularly in the physical and functional domains. Using this information and following guidance on the development of patient-reported outcome (PRO) measures, we determined which combination of measures and items (ie, specific questions) would be most appropriate in a survey assessing HRQoL in bloodstream infections.

METHODS

We selected a variety of measures/items from the Patient-Reported Outcomes Measurement Information System (PROMIS) representing different domains. We purposefully sampled patients ~6-12 weeks post-SAB/GNB and conducted 2 rounds of cognitive interviews to refine the survey by exploring patients' understanding of items and answer selection as well as relevance for capturing HRQoL.

RESULTS

We interviewed 17 SAB/GNB patients. Based on the first round of cognitive interviews (n = 10), we revised the survey. After round 2 of cognitive interviewing (n = 7), we finalized the survey to include 10 different PROMIS short forms/measures of the most salient HRQoL domains and 2 adapted questions (41 items total) that were found to adequately capture HRQoL.

CONCLUSIONS

We developed a survey from well-established PRO measures that captures what matters most to SAB/GNB patients as they recover. This survey, uniquely tailored to bloodstream infections, can be used to assess these meaningful, important HRQoL outcomes in clinical trials and in patient care. Engaging patients is crucial to developing treatments for bloodstream infections.

Evaluation of step-down oral antibiotic therapy for uncomplicated streptococcal bloodstream infections on clinical outcomes

Background:

Despite the severity and frequency of streptococcal bloodstream infections (BSIs), the effectiveness of oral definitive therapy remains unknown. The objective of this study was to evaluate the clinical outcomes of step-down oral antibiotics for the treatment of uncomplicated streptococcal BSIs.

Methods:

In this retrospective cohort study, adult patients admitted with uncomplicated streptococcal BSI between June 2015 and June 2017 were included. Patients were excluded if they received <48 h of antibiotic therapy; therapy was started >48 h after first positive culture; had complicated infections of endocarditis, bone and joint infections, or central nervous system infections; Pitt bacteremia score (PBS) ⩾ 4; or failed to respond to effective therapy necessitating continued intravenous (IV) therapy. Patients were grouped by receipt of step-down oral antibiotic therapy (PO group) versus continued IV therapy (IV group). Outcomes included hospital length of stay (LOS), 30-day recurrence of BSI, 30-day readmission, 30-day all-cause mortality, and catheter-related or drug-related adverse events (AEs).

Results:

Of 244 patients included, 40% received step-down oral therapy (n = 98). Overall, the most common source of BSI was pneumonia (22%), followed by skin and soft tissue infections (SSTI) (18%). Severity of illness measured by intensive care unit (ICU) admission and PBS was similar. The IV group had significantly longer LOS [median 10 (interquartile range [IQR] = 5–21) versus 5 (4–6) days, p < 0.01] compared with the PO group. BSI recurrence, readmission, all-cause mortality within 30 days, and AEs were similar between the groups (p = ns).

Conclusion:

In uncomplicated streptococcal BSI, patients treated with step-down oral antibiotic therapy had significantly shorter LOS compared with continued IV therapy without compromise of clinical outcomes.

Comparative 1-Year Outcomes of Invasive Staphylococcus aureus Infections Among Persons With and Without Drug Use: An Observational Cohort Study

BACKGROUND

Persons who use drugs (PWUD) face substantial risk of Staphylococcus aureus infections. Limited data exist describing clinical and substance use characteristics of PWUD with invasive S. aureus infections or comparing treatment and mortality outcomes in PWUD vs non-PWUD. These are needed to inform optimal care for this marginalized population.

METHODS

We identified adults hospitalized from 2013 to 2018 at 2 medical centers in San Francisco with S. aureus bacteremia or International Classification of Diseases-coded diagnoses of endocarditis, epidural abscess, or vertebral osteomyelitis with compatible culture. In addition to demographic and clinical characteristic comparison, we constructed multivariate Cox proportional hazards models for 1-year infection-related readmission and mortality, adjusted for age, race/ethnicity, housing, comorbidities, and methicillin-resistant S. aureus (MRSA).

RESULTS

Of 963 hospitalizations for S. aureus infections in 946 patients, 372 of 963 (39%) occurred in PWUD. Among PWUD, heroin (198/372 [53%]) and methamphetamine use (185/372 [50%]) were common. Among 214 individuals using opioids, 98 of 214 (46%) did not receive methadone or buprenorphine. PWUD had lower antibiotic completion than non-PWUD (70% vs 87%; P < .001). While drug use was not associated with increased mortality, 1-year readmission for ongoing or recurrent infection was double in PWUD vs non-PWUD (28% vs 14%; adjusted hazard ratio [aHR], 2.0 [95% confidence interval {CI}: 1.3-2.9]). MRSA was independently associated with 1-year readmission for infection (aHR, 1.5 [95% CI: 1.1-2.2]).

CONCLUSIONS

Compared to non-PWUD, PWUD with invasive S. aureus infections had lower rates of antibiotic completion and twice the risk of infection persistence/recurrence at 1 year. Among PWUD, both opioid and stimulant use were common. Models for combined treatment of substance use disorders and infections, particularly MRSA, are needed.

Clindamycin Efficacy in Patients With Methicillin-Sensitive Staphylococcus aureus in a Fourth-Level Hospital in the City of Medellín

Background: The antibiotic of choice for methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia is antistaphylococcal penicillins, such as oxacillin, but cefazolin has also risen as an equally effective alternative. Murine models have suggested that clindamycin is a therapeutic alternative for Staphylococcus aureus bacteremia (SAB).

Methods: In this retrospective cohort study, patients from the Hospital Universitario San Vicente Fundación (HUSVF) in Medellín, Colombia, were recruited from January 2013 and December 2019. Patients with positive blood culture for MSSA, with at least one follow-up blood culture, and those with more than 72 hours of parenteral antibiotic therapy for SAB were selected. The main objective was to determine the efficacy of clindamycin compared to other antibiotics to achieve a microbiologic cure. Secondary results included in-hospital mortality and hospital stay.

Results: A total of 486 patients were included (clindamycin = 50 and other anti-MSSA = 436). The patients in the clindamycin group had a lower rate of microbiological cure (n = 41 [84%]) compared to other antibiotics (n = 367 [84%]) (OR 1.08 IC 95% 0.74-1.58). In secondary outcomes, no statistically significant differences were observed in the in-hospital mortality. The main source of SAB was a central or peripheral catheter (58%).

Conclusions: Our study found no differences in the rate of microbiological cure, in-hospital mortality, and hospital stay on the clindamycin group compared to other anti-MSSA antibiotics. However, in patients with metastatic complications, the rate of microbiological cure is reduced, and the in-hospital mortality is higher in patients with more severe disease.

Acute kidney injury in Staphylococcus aureus bacteremia

Acute kidney injury (AKI) is a frequent complication in patients with Staphylococcus aureus bacteremia (SAB), with a significant impact on patient management and outcome. This study aimed to provide insight in the proportion of patients with SAB that develop AKI, the risk factors for developing AKI in this population, and its reversibility. In this retrospective, multicenter cohort study, adult patients with SAB were eligible for inclusion. Patient characteristics, clinical variables, and laboratory results were retrieved from the electronic patient files. Primary outcome was development of AKI, defined as 1.5 times baseline creatinine. Secondary outcomes were reversibility of AKI and risk factors for AKI. A total of 315 patients with SAB were included, of whom 115/315 (37%) developed acute kidney injury. In 68/115 (59%), the AKI was reversible. If kidney function recovered, this occurred within 7 days in 56/68 (82%) of patients. In multivariable logistic regression analyses, independent risk factors for AKI were as follows: complicated SAB, use of diuretics, and hemodynamic instability. Development of AKI was associated with 30-day mortality (OR 3.9; CI 2.2-6.9; p < 0.01). Acute kidney injury is a frequent complication in patients with Staphylococcus aureus bacteremia. Considering the irreversibility in a relevant proportion of patients, future research into the underlying pathophysiology and potential interventions is warranted.

The LAUsanne STAPHylococcus aureus ENdocarditis (LAUSTAPHEN) score: A prediction score to estimate initial risk for infective endocarditis in patients with S. aureus bacteremia

Introduction

Infective endocarditis (IE) is a common complication of Staphylococcus aureus bacteremia (SAB). The study aimed to develop and validate a prediction score to determine IE risk among SAB.

Methods

This retrospective study included adults with SAB (2015-2021) and divided them into derivation and validation cohorts. Using the modified 2015 European Society of Cardiology modified Duke Criteria for definite IE, the LAUSTAPHEN score was compared to previous scores.

Results

Among 821 SAB episodes, 419 and 402 were divided into derivation and validation cohorts, respectively. Transthoracic and transoesophageal echocardiography (TOE) were performed in 77.5 and 42.1% of episodes, respectively. Definite IE was diagnosed in 118 episodes (14.4%). Derivation cohort established that cardiac predisposing factors, such as cardiac implantable electronic devices, prolonged bacteremia ≥48 h, and vascular phenomena were independently associated with IE. In addition to those parameters, native bone and joint infections were used to constitute the LAUSTAPHEN score. LAUSTAPHEN and VIRSTA scores misclassified <4% of IE cases as low risk. Misclassification using POSITIVE and PREDICT scores was >10%. The number of TOEs required to safely exclude IE were 66.9 and 51.6% with VIRSTA and LAUSTAPHEN, respectively.

Discussion

LAUSTAPHEN and VIRSTA scores exhibited the lowest misclassification rate of IE cases to the low-risk group. However, the number of patients requiring TOE was higher for VIRSTA than for LAUSTAPHEN.

Individualizing the use of [18F]FDG-PET/CT in patients with complicated Staphylococcus aureus bacteremia: experiences from a tertiary care center

Purpose

[¹⁸F]FDG-PET/CT scanning can help detect metastatic infectious foci and reduce mortality in patients with Staphylococcus aureus bacteremia (SAB), but it is unknown if patients with SAB and an indication for prolonged treatment because of possible endovascular, orthopaedic implant, or other metastatic infection still need [¹⁸F]FDG-PET/CT.

Methods

In a retrospective single-center cohort study, we included all consecutive adult patients with SAB between 2013 and 2020 if an [¹⁸F]FDG-PET/CT scan was performed and antibiotic treatment was planned for ≥ 6 weeks prior to [¹⁸F]FDG-PET/CT. We aimed to identify patients for whom treatment was adjusted due to the results of [¹⁸F]FDG-PET/CT, and assessed concordance of [¹⁸F]FDG-PET/CT and clinical diagnosis for infected prosthetic material.

Results

Among 132 patients included, the original treatment plan was changed after [¹⁸F]FDG-PET/CT in 22 patients (16.7%), in the majority (n = 20) due to diagnosing or rejecting endovascular (graft) infection. Antibiotic treatment modifications were shortening in 2, iv-oral switch in 3, extension in 13, and addition of rifampicin in 4 patients. Ninety additional metastatic foci based on [¹⁸F]FDG-PET/CT results were found in 69/132 patients (52.3%). [¹⁸F]FDG-PET/CT suggested vascular graft infection in 7/14 patients who lacked clinical signs of infection, but showed no infection of prosthetic joints or osteosynthesis material in eight patients who lacked clinical signs of such an infection.

Conclusion

[¹⁸F]FDG-PET/CT can help refine treatment for SAB in patients with clinically suspected endovascular infection or vascular grafts, even if 6 weeks treatment is already indicated, but can be safely omitted in other patients who are clinically stable.

Supplementary Information

The online version contains supplementary material available at 10.1007/s15010-021-01740-4.

Ceftriaxone versus antistaphylococcal antibiotics for definitive treatment of methicillin-susceptible Staphylococcus aureus infections: a systematic review and meta-analysis

Optimal therapy for methicillin-susceptible Staphylococcus aureus (MSSA) infections is unclear. Current standard of care consists of antistaphylococcal antibiotics (ASAs) such as nafcillin, oxacillin and cefazolin. Ceftriaxone has been evaluated due to its advantage as a once-daily outpatient regimen. However, questions remain regarding its efficacy compared with ASAs. We aimed to conduct a review and synthesis of available literature for outcomes of patients treated with ceftriaxone or ASAs for MSSA infections. We searched Cochrane Central Register of Controlled Trials, Embase Ovid, MEDLINE Ovid, Scopus and Web of Science (1990 to June 2021). Risk of bias for cohort studies was assessed by the Newcastle-Ottawa scale. We pooled risk ratios (RRs) using the DerSimonian-Laird random-effects model for outcomes of those receiving ceftriaxone versus ASAs. Heterogeneity was assessed by the I² index. From 459 identified studies, 7 were included in the quantitative synthesis totalling 1640 patients. Definitive therapy with ceftriaxone was associated with a lower risk of toxicity requiring therapy alteration (RR 0.49, 95% CI 0.27-0.88; I² = 0%). There was no difference in terms of 90-day all-cause mortality (RR 0.93, 95% CI 0.46-1.88; I² = 9%), hospital readmission (RR 0.96, 95% CI 0.57-1.64; I² = 0%) or infection recurrence (RR 1.04, 95% CI 0.63-1.72; I² =0%). Current evidence suggests there is no difference in efficacy between ceftriaxone and ASAs for MSSA infection, with a lower risk of toxicity with ceftriaxone. Within the limitations of available retrospective studies, ceftriaxone is a consideration for definitive therapy of MSSA infection. [Trial registration: PROSPERO ID: CRD42021259086].

Evaluation of antimicrobial activity of bacterial symbionts isolated from wild field cockroach Blattella vaga from Saudi Arabia

Drug-resistant pathogens form the main threat to global health during the current century. Annually, a lot of patients die in hospitals due to infection with one or more drug-resistant bacteria especially Staphylococcus aureus (MRSA). In the absence of new effective antimicrobial drugs, the number of deaths said to be increased. Searching for new antibiotics in our backyard form a part of scientist strategies to solve such serious health problem. Insects consider one of such interesting sources of the new era of antimicrobial drugs. Cockroaches as an example can live and adapt in a polluted area for a long time, so through this work field cockroach, Blattella vaga was collected from two semi-wild areas around Riyadh, Saudi Arabia for isolation of gut bacteria searching for new antimicrobial agents. Three species of bacteria were identified from field cockroach gut: Bacillus licheniformis, Bacillus subtilis, and Kocuria rosea. The three species were isolated, purified, and tested for their antimicrobial activity against four drug-resistant pathogens (three bacteria: Salmonella enterica (ATCC25566), Staphylococcus aureus (MRSA) (Clinical strain), and Streptococcus mutans (RCMB 017(1) ATCC ® 25175™) and one fungus: Candida albicans (RCMB005003(1) ATCC® 10231™)). The results show no antimicrobial activity of Bacillus subtilis and very good activity Bacillus licheniformis and Kocuria rosea. Bacillus licheniformis gives very effective activity against Candida albicans while Kocuria rosea is effective against MRSA and Streptococcus mutans. None of the gut isolated bacteria show any activity against Salmonella enterica. Such results revealed that the metabolites of these bacteria could be used as substitutes to the already used antibiotics to overcome the problem of multidrug-resistant human pathogens.

Rapid visualization and detection of Staphylococcus aureus based on loop-mediated isothermal amplification

Staphylococcus aureus is a common clinical bacterial pathogen that can cause a diverse range of infections. The establishment of a rapid and reliable assay for the early diagnosis and detection of S. aureus is of great significance. In this study, we developed a closed-tube loop-mediated isothermal amplification (LAMP) assay for the visual detection of S. aureus using the colorimetric indicator hydroxy naphthol blue (HNB). The LAMP reaction was optimized by adjusting the amplification temperature, the concentrations of Mg²⁺, dNTP, and HNB, and the incubation time. In the optimized reaction system, the specificity of LAMP for S. aureus was 100%. The results established that this method accurately identified S. aureus, with no cross-reactivity with 14 non-S. aureus strains. The limit of detection (LOD) of LAMP was 8 copies/reaction of purified plasmid DNA or 400 colony-forming units/reaction of S. aureus. Compared with conventional PCR, LAMP lowered the LOD by tenfold. Finally, 220 clinically isolated strains of S. aureus and 149 non-S. aureus strains were used to evaluate the diagnostic efficacy of LAMP (test accuracy, 99.46%). The findings indicated that LAMP is a reliable test for S. aureus and could be a promising tool for the rapid diagnosis of S. aureus infections.

"Mortality in Staphylococcus aureus bacteraemia remains high despite adherence to quality indicators: secondary analysis of a prospective cohort study"

OBJECTIVES

To evaluate the association between compliance with previously published quality indicators (QIs) for the management of Staphylococcus aureus bacteraemia (SAB) and 30-day mortality.

METHODS

We conducted a post hoc analysis of all adult patients with SAB who were hospitalized at a Spanish university hospital between 2013 and 2018. We evaluated the compliance with 7 QIs of SAB management (i.e., Infectious Diseases consultation, follow-up blood cultures, early source control, echocardiography, early cloxacillin or cefazolin, vancomycin monitoring, and appropriate treatment duration). The QIs compliance rate was considered good if ≥75% of the QIs recommended in each patient were performed. We studied the impact of different risk factors (including QIs compliance) on 30-day all-cause mortality adjusting by multivariable modeling and propensity-matched analysis.

RESULTS

We included 441 patients with SAB. The QIs compliance rate was ≥75% in 361 patients (81.9%). A total of 95 patients (21.5%) died within 30 days after the index blood culture. In the multivariable model, the variables associated with 30-day mortality were: age (OR, 1.1; 95% CI, 1.0-1.1), Charlson comorbidity index (OR, 1.2; 95% CI, 1.1-1.4), persistent bacteraemia >72 h (OR, 6.0; 95% CI, 3.2-11.5), infective endocarditis (OR, 2.8; 95% CI, 1.2-6.7), and SAB of unknown source (OR, 3.3; 95% CI, 1.5-7.1). We did not find an association between a global QIs compliance rate of ≥75% or any individual QI with 30-day mortality.

CONCLUSIONS

SAB 30-day mortality remains high despite good adherence to previously published QIs for the management of SAB. Future research should focus on additional factors to further improve SAB-related mortality.

The Effect of Combination Therapy on Mortality and Adverse Events in Patients with Staphylococcus aureus Bacteraemia: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Introduction

The findings of randomized controlled trials (RCTs), observational studies, and meta-analyses vary regarding the effectiveness and safety of combination therapy for patients with Staphylococcus aureus bacteraemia (SAB). We aimed to identify the effectiveness and safety of combination therapy in patients with SAB compared with those of monotherapy.

Methods

We performed a systematic review and meta-analysis to compare combination therapy versus monotherapy in patients with SAB. Two authors independently searched PubMed, Embase, and the Cochrane Library of clinical trials until 17 February 2021. Any RCT comparing mortality or adverse events (AEs) of combination therapy versus monotherapy for patients with SAB was eligible. Summary risk ratios (RRs) and 95% confidence intervals (CIs) were evaluated using a random-effects model. The primary outcome was all-cause mortality at any time point. This meta-analysis is registered with the PROSPERO database (CRD42020188176) and reported according to PRISMA guidelines.

Results

In total, 1906 articles were identified and screened, and 14 studies (2367 patients) were included in the meta-analysis. There was no significant difference in the risk of all-cause mortality between the two groups (RR = 1.00; 95% CI 0.83–1.20; P = 0.99; I² = 0%). Similar results were obtained by subgroup analysis of mortality recording time, endocarditis, pathogen resistance, article publication time, number of patients, and adjuvant antibiotics. Notably, combination treatment might significantly increase the risk of drug-related AEs (RR = 1.68; 95% CI 1.06–2.66; P = 0.03; I² = 67%) and nephrotoxicity (RR = 2.30; 95% CI 1.68–3.16; P < 0.00001; I² = 0%), although the occurrences of AEs leading to treatment discontinuation and serious AEs were not significantly different between the two groups.

Conclusions

The meta-analysis suggested that combination therapy could not reduce mortality but might increase the risk of drug-related AEs and nephrotoxicity and should be applied very cautiously. Future studies on combined drug therapy for SAB need careful and rigorous design for specific antibiotic combinations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00539-y.

Ascending Cholangitis Caused by Methicillin-Resistant Staphylococcus aureus Species in a Patient With Cystic Fibrosis

Ascending cholangitis is a bacterial infection of the extra-hepatic biliary system and presents as a life-threatening systemic condition. Increased bacterial loads and biliary obstruction favor bacterial translocation into the vascular and lymphatic systems. Common organisms isolated are Escherichia Coli, Klebsiella, Enterococcus species, and Enterobacter species. Methicillin-resistant Staphylococcus aureus (MRSA) is a rare isolate in ascending cholangitis. We present a case of a 24-year-old patient with cystic fibrosis who presented with epigastric abdominal pain, low-grade fever, jaundice, dark urine, and nausea for two days. Initial workup revealed elevated liver enzymes, hyperbilirubinemia, leukocytosis, and an ultrasound which showed common bile duct dilation to 14 mm with choledocholithiasis. He underwent endoscopic retrograde cholangiopancreatography (ERCP) with stone extraction and bile fluid culture. Cultures grew out MRSA and the patient was treated with appropriate antibiotic therapy. The mainstay of therapy for ascending cholangitis is adequate hydration, antibiotics, and biliary decompression. Early recognition of the offending organism is critical in guiding therapy. Current guidelines focus on the empiric treatment of Gram-negative and anaerobic bacteria. Clinicians should be aware of the possibility of less common pathogens (such as MRSA), especially in a patient who is decompensating despite antibiotic therapy.

Identification of Small Molecule Inhibitors against Staphylococcus aureus Dihydroorotase via HTS

Drug-resistant Staphylococcus aureus is an imminent threat to public health, increasing the importance of drug discovery utilizing unexplored bacterial pathways and enzyme targets. De novo pyrimidine biosynthesis is a specialized, highly conserved pathway implicated in both the survival and virulence of several clinically relevant pathogens. Class I dihydroorotase (DHOase) is a separate and distinct enzyme present in gram positive bacteria (i.e., S. aureus, B. anthracis) that converts carbamoyl-aspartate (Ca-asp) to dihydroorotate (DHO)-an integral step in the de novo pyrimidine biosynthesis pathway. This study sets forth a high-throughput screening (HTS) of 3000 fragment compounds by a colorimetry-based enzymatic assay as a primary screen, identifying small molecule inhibitors of S. aureus DHOase (SaDHOase), followed by hit validation with a direct binding analysis using surface plasmon resonance (SPR). Competition SPR studies of six hit compounds and eight additional analogs with the substrate Ca-asp determined the best compound to be a competitive inhibitor with a K_D value of 11 µM, which is 10-fold tighter than Ca-asp. Preliminary structure-activity relationship (SAR) provides the foundation for further structure-based antimicrobial inhibitor design against S. aureus.

One-third of people who inject drugs are at risk of incomplete treatment for Staphylococcus aureus bacteraemia: a retrospective medical record review

Staphylococcus aureus bacteraemia (SAB) is often a complication of injecting drug use, and is associated with high morbidity and mortality. This article reports the first audit of inpatient parenteral treatment of SAB completion among people who inject drugs (PWID) in Australia. Of 198 patients admitted with SAB, 106 were analysed. Twelve PWID had an inpatient stay <14 days compared with seven non-PWID (34% vs 10%; P=0.002). Sixteen PWID experienced discharge against medical advice compared with zero non-PWID (46% vs 0%; P<0.001). Re-admission to hospital within 28 days was 2.5 times greater among PWID than non-PWID (31% vs 15%; P=0.026). Methadone dose <60 mg/day was associated with premature discharge in opioid-dependent PWID receiving methadone (n=21, 100% vs 31%; P=0.012).

Valvular and infection-associated risk factors as criteria to guide the use of echocardiography in patients with native joint infections

BACKGROUND

Native joint and bone infections (NJBI) are associated with infective endocarditis (IE) in 15% of cases. There are no studies analyzing the use of cardiac imaging in cases of NJBI. The objective of this study was to identify factors associated with echocardiography suggestive of IE in patients with NJBI.

METHODS

This medical records review was conducted in patients hospitalized for NJBI between 2007 and 2017 in Rheumatology and Infectious Diseases departments of 2 university hospitals. Patients included had a microbiologically proven NJBI during their hospitalization.

RESULTS

In this cohort of 546 patients, median age 66 years, echocardiography was suggestive of IE in 66 (12%). In multivariate analysis, factors associated with echocardiography suggestive of IE were 2 or more positive blood cultures (OR 11.55 (CI95% 3.24-74.20)), cardiac conditions with a high risk of IE (OR 7.34 (CI95% 2.95-18.61)), unknown heart murmur (OR 4.59 (CI95% 1.79-11.74)), multifocal infection (OR 2.26 (CI95% 1.21-4.23)) and an infection due to S. bovis (OR 3.52 (CI95% 1.26-9.79)). The factor associated with the absence of an echocardiography evocative of IE was infection due to unconventional bacteria for IE (OR 0.13 (CI95% 0.01-0.76)). According to the factors associated with echocardiography evocative of IE, we propose the Normandy score based on three kinds of data: cardiac condition, bacterial strain and NJBI mechanism. Echocardiography should be realized when this score, whose negative predictive value is 100% CI95% (98-100%) for prescription of echocardiography, is more than zero.

CONCLUSIONS

A score based on valvular condition, bacterial strain and NJBI mechanism could guide clinicians in prescribing echocardiography during NJBI with an excellent negative predictive value.

Linezolid Induced Skin Reactions in a Multi Drug Resistant Infective Endocarditis Patient: A Rare Case

RATIONALE

Linezolid (LNZ) induced Cutaneous Adverse Drug Reactions (CADRs) have rare atypical presentation. Till date, there are very few published case reports on LNZ induced CADRs among the multidrug-resistant patients suffering from Infective Endocarditis (MDR IE). Here, we present a rare case report of LNZ induced CARs in a MDR IE patient.

CASE REPORT

A 24-year-old female patient was admitted to the hospital with chief complaints of fever (101°C) associated with rigors, chills, and shortness of breath (grade IV) for the past 4 days. She was diagnosed with MDR IE, having a prior history of rheumatic heart disease. She was prescribed LNZ 600mg IV BD for MDR IE, against Staphylococcus coagulase-negative. The patient experienced flares of cutaneous reactions with multiple hyper-pigmented maculopapular lesions all over the body after one week of LNZ therapy. Upon causality assessment, she was found to be suffering from LNZ induced CADRs. LNZ dose was tapered gradually and discontinued. The patient was prescribed corticosteroids along with other supportive care. Her reactions completely subsided and infection got controlled following 1 month of therapy.

CONCLUSION

Healthcare professionals should be vigilant for rare CADRs, while monitoring the patients on LNZ therapy especially in MDR patients as they are exposed to multiple drugs. Moreover, strengthened spontaneous reporting is required for better quantification.

Patients' Experiences With Staphylococcus aureus and Gram-negative Bacterial Bloodstream Infections: A Qualitative Descriptive Study and Concept Elicitation Phase To Inform Measurement of Patient-reported Quality of Life

BACKGROUND

Although Staphylococcus aureus and gram-negative bacterial bloodstream infections (SAB/GNB) cause substantial morbidity, little is known regarding patient perceptions' of their impact on quality of life (QOL). Guidance for assessing QOL and disease-specific measures are lacking. We conducted a descriptive qualitative study to gain an in-depth understanding of patients' experiences with SAB/GNB and concept elicitation phase to inform a patient-reported QOL outcome measure.

METHODS

We conducted prospective one-time, in-depth, semi-structured, individual, qualitative telephone interviews 6- 8 weeks following bloodstream infection with either SAB or GNB. Patients were enrolled in an institutional registry (tertiary academic medical center) for SAB or GNB. Interviews were audio-recorded, transcribed, and coded. Directed content analysis identified a priori and emergent themes. Theme matrix techniques were used to facilitate analysis and presentation.

RESULTS

Interviews were completed with 30 patients with SAB and 31 patients with GNB. Most patients were at or near the end of intravenous antibiotic treatment when interviewed. We identified 3 primary high-level concepts: impact on QOL domains, time as a critical index, and sources of variability across patients. Across both types of bloodstream infection, the QOL domains most impacted were physical and functional, which was particularly evident among patients with SAB.

CONCLUSIONS

SAB/GNB impact QOL among survivors. In particular, SAB had major impacts on multiple QOL domains. A combination of existing, generic measures that are purposefully selected and disease-specific items, if necessary, could best capture these impacts. Engaging patients as stakeholders and obtaining their feedback is crucial to conducting patient-centered clinical trials and providing patient-centered care.

Case report: appendicitis induced Staphylococcus aureus and Klebsiella pneumoniae bacteremia in a young healthy male

Background

Appendicitis is one of the most frequently encountered conditions at the emergency department. Distinction is made between complicated and uncomplicated appendicitis. Complicated appendicitis may cause serious intra-abdominal infection, bacteremia, or sepsis. Emergency health providers should be highly alert to any early signs indicating such complications.

Case presentation

We present the case of a healthy young male with a gangrenous appendicitis, who received antibiotics and underwent appendectomy. Blood cultures showed unequivocal Staphylococcus aureus and concomitant Klebsiella pneumoniae bacteremia requiring prolonged antibiotic treatment and further diagnostic evaluation.

Conclusions

Although rare, appendicitis can cause Staphylococcus aureus and Klebsiella pneumoniae bacteremia with extensive implications for workup and antibiotic management. Our case stresses the importance of obtaining cultures in patients with suspicion of bacteremia given its consequences for clinical management.

Adjunctive Daptomycin in the Treatment of Methicillin-susceptible Staphylococcus aureus Bacteremia: A Randomized, Controlled Trial

BACKGROUND

Bloodstream infections (BSIs) with methicillin-susceptible Staphylococcus aureus (MSSA) are associated with significant morbidity and mortality. Our objective in this study was to determine the efficacy of synergistic treatment with daptomycin when given with either cefazolin or cloxacillin for the treatment of MSSA BSI.

METHODS

A randomized, double-blind, placebo-controlled trial was performed at 2 academic hospitals in Montreal, Canada. Patients aged ≥18 years with MSSA BSI receiving either cefazolin or cloxacillin monotherapy were considered for inclusion. In addition to the standard-of-care treatment, participants received a 5-day course of adjunctive daptomycin or placebo. The primary outcome was the duration of MSSA BSI in days.

RESULTS

Of 318 participants screened, 115 were enrolled and 104 were included in the intention-to-treat analysis (median age, 67 years; 34.5% female). The median duration of bacteremia was 2.04 days among patients who received daptomycin vs 1.65 days in those who received placebo (absolute difference, 0.39 days; P = .40). In a modified intention-to-treat analysis that involved participants who remained bacteremic at the time of enrollment, we found a median duration of bacteremia of 3.06 days among patients who received daptomycin vs 3.0 days in those who received placebo (absolute difference, 0.06 days; P = .77). Ninety-day mortality in the daptomycin arm was 18.9% vs 17.7% in the placebo arm (P = 1.0).

CONCLUSIONS

Among patients with MSSA BSIs, the administration of adjunctive daptomycin therapy to standard-of-care treatment did not shorten the duration of bacteremia and should not be routinely considered.

CLINICAL TRIALS REGISTRATION

NCT02972983.

Enterococcus faecalis in blood cultures-a prospective study on the role of persistent bacteremia

Enterococcus faecalis can cause infective endocarditis and other complicated infections. We prospectively investigate the incidence of persistent bacteremia with E. faecalis. Of 50 episodes with monomicrobial E. faecalis bacteremia the control blood culture after 48 to 72 hours was positive in 5 episodes (10%) of which 4 had a complicated focal infection.

Role of echocardiography in uncomplicated Staphylococcus aureus catheter-related bloodstream infections

Uncomplicated bacteremia and catheter-related bloodstream infection (CRBSI) are frequently suggested as factors associated with low risk of infective endocarditis in Staphylococcus aureus bacteremia (SAB). Nevertheless, guidelines recommend that echocardiography in all patients with SAB. We evaluated the effects of echocardiography on patient outcomes. Patients with uncomplicated S. aureus CRBSI were retrospectively identified between January 2013 and June 2018 at a 1950-bed, tertiary-care university hospital. Treatment failure was defined as any case of relapse or all-cause death within 90 days. Of 890 SAB patients, 95 with uncomplicated S. aureus CRBSI were included. Thirty-two patients underwent echocardiography within 30 days of their first positive blood culture. Two patients who underwent echocardiography revealed right-sided infective endocarditis. One patient who did not undergo echocardiography experienced recurrent SAB (peripheral CRBSI) 85 days after his first positive blood culture. There were no SAB-related deaths. The Kaplan-Meier curves of treatment failure showed no significant differences between patients who did and did not undergo echocardiography (P = .77). In multivariable analysis, risk factors for treatment failure were liver cirrhosis (hazard ratio: 9.60; 95% confidence interval: 2.13-43.33; P = .003) and other prostheses (hazard ratio: 63.79; 95% confidence interval: 5.05-805.40; P = .001). This study did not verify the putative association between treatment failure and implementation of echocardiography in patients with uncomplicated S. aureus CRBSI. Given the low observed rates of adverse outcomes, routine echocardiography might not be obligatory and could be performed on an individual basis.