Predictors of mortality in Staphylococcus aureus Bacteremia

Impact of a kidney-sparing protocol for the treatment of methicillin-susceptible Staphylococcus aureus bloodstream infections (CLOXECO): a quasi-experimental study

BACKGROUND

Antistaphylococcal penicillin (ASP) is the first-line therapy for MSSA bloodstream infection (BSI), with cefazolin as an alternative. However, ASPs are associated with a high risk of acute kidney injury (AKI) and overexposure. We implemented a kidney-sparing protocol based on: (i) systematic use of cefazolin in patients with creatinine clearance of <60 mL/min or any risk factor for AKI; and (ii) reduced ASP dose (75-100 mg/kg/day) with therapeutic drug monitoring.

METHODS

We compared all episodes of MSSA BSI in adults admitted during the 15 months before (control period) and the 12 months after (optimization period) protocol implementation. Primary outcome was sterile blood cultures by Day 3. Secondary outcomes included AKI, dialysis, MSSA BSI relapses, and mortality.

RESULTS

We included 100 patients in the control group and 104 in the optimization group. Baseline characteristics were similar in both groups, with a mean ± SD age of 73 ± 20 years, male predominance (73%), and high prevalence of chronic kidney disease (80%) and diabetes (31%). Initial treatment was ASP (cloxacillin) in 80/100 (80%) patients in the control group, versus 24/104 (23%) in the optimization group (P < 0.001). Day 3 sterile blood cultures, and Day 30 mortality remained similar (respectively 95% versus 93%, and 21% versus 24%; not significant). AKI and dialysis requirements were less frequent during the optimization period, respectively 37% versus 56% (P = 0.045), and 1% versus 8% (P = 0.017).

CONCLUSIONS

A kidney-sparing protocol for MSSA BSI based on systematic use of cefazolin in patients with AKI risk factor, and lower ASP doses, was associated with similar efficacy and lower risk of AKI and dialysis requirements.

Ceftaroline for bloodstream infections caused by methicillin-resistant Staphylococcus aureus: a multicentre retrospective cohort study

OBJECTIVES

To evaluate the effectiveness of ceftaroline vs. vancomycin or daptomycin in the treatment of methicillin-resistant Staphylococcus aureus bloodstream infections (BSIs) (MRSA-BSIs).

METHODS

This multicentre retrospective study conducted in 15 Spanish hospitals included data from the first MRSA-BSIs of adult patients between January 2019 and December 2022. The ceftaroline group included patients who received ceftaroline for ≥72 hours within the first week of BSI onset; the standard-of-care (SOC) group included patients who received vancomycin or daptomycin ≥72 hours after BSI onset. Primary outcome was 30-day all-cause mortality; secondary outcomes included 90-day mortality and incidence of adverse events (AEs). Propensity-score matching and Cox proportional hazards analyses were performed.

RESULTS

A total of 429 MRSA-BSIs were included: 133 in the ceftaroline group and 296 in the SOC group. More patients in the ceftaroline group had a Sequential Organ Failure Assessment score >2 (51.1% vs. 36.5%; p < 0.01), complicated BSI (66.2% vs. 42.2%; p < 0.01), infective endocarditis (18.8% vs. 6.4%; p < 0.01) and prescribed in combination treatment (65.4% vs. 11.5%; p < 0.01), with no statistically significant differences in 30-day mortality: 23.3% ceftaroline (95% CI, 16.1-30.5%) vs. 16.2% SOC (95% CI, 12.0-20.4%), p 0.08. There were no statistically significant differences in 90-day mortality (33.1% ceftaroline vs. 26.7% SOC; p 0.17). After propensity-score matching, 105 patients treated with ceftaroline were matched with 105 controls: the 30-day mortality rates were 21.9% and 16.2% (p 0.38). Cox regression analysis of the entire cohort (n = 429) revealed that age (hazard ratio [HR], 1.05; 95% CI, 1.03-1.07) and Sequential Organ Failure Assessment score >2 (HR, 2.34; 95% CI, 1.50-3.65) were associated with 90-day mortality risk, although ceftaroline treatment did not demonstrate a significant effect (HR, 1.00; 95% CI, 0.97-1.02). Incidence of AEs was 12.0% in ceftaroline vs. 4.4% in the SOC group (p < 0.01). Most AEs occurred when ceftaroline was used in combination vs. monotherapy (17.2% vs. 2.2%; p 0.01).

DISCUSSION

Ceftaroline was an effective treatment for MRSA-BSIs but was commonly prescribed in combination showing a higher incidence of AEs.

Time to Staphylococcus aureus Blood Culture Positivity as a Risk Marker of Infective Endocarditis: A Retrospective Cohort Study

BACKGROUND

Endocarditis occurs in approximately 10%-15% of patients with Staphylococcus aureus bacteremia (SAB). Short time to positivity (TTP) in blood culture flasks has been linked to endocarditis in smaller studies. This study evaluated the association between TTP and endocarditis in SAB in a large cohort.

METHODS

Adult patients with ≥1 S. aureus positive blood culture treated at a tertiary-level, 500-bed hospital in Stockholm, Sweden between 2011-2021 were retrospectively identified. The primary outcome was the presence of infective endocarditis.

RESULTS

A total of 1703 episodes of SAB (23/1703 methicillin-resistant) in 1610 patients were included. Median age was 75 (interquartile range [IQR], 63-84) years and median Charlson comorbidity index score was 2 (IQR, 1-3). Echocardiography was performed in 1102/1703 (65%). Thirty-day mortality was 406/1703 (24%) and endocarditis was found in 154/1703 (9%). Median TTP was shorter in patients with endocarditis (9 [IQR, 7-12] hours) compared to patients without endocarditis (13 [interquartile range, 10-18] hours; P < .001). The risk of endocarditis decreased with 11% per hour (odds ratio [OR], 0.89 [95% confidence interval {CI}, .54-.92]; P < .001) in a univariate analysis using TTP as a continuous variable. In multivariate analysis, TTP <13 hours (the median) was independently associated with endocarditis (OR, 3.59 [95% CI, 2.35-5.3]; P < .001). The negative predictive value of TTP >13 hours for endocarditis was 96% (95% CI, 95%-97%).

CONCLUSIONS

Short TTP was associated with endocarditis. The negative predictive value of >95% suggests that TTP >13 hours can be used to risk-stratify patients with SAB.

Antibiotic therapy and clinical outcomes of penicillin-susceptible Staphylococcus aureus (PSSA) bloodstream infection (BSI): a ten-year retrospective cohort study

In recent years, the incidence of penicillin-susceptible S. aureus (PSSA) bloodstream infection (BSI) has increased worldwide. However, the preferred antibiotic remains uncertain due to concerns of inducible resistance to benzylpenicillin. We compared outcomes associated with benzylpenicillin versus other antibiotics and investigated risk factors influencing treatment failure. Patients were grouped into benzylpenicillin and non-benzylpenicillin beta-lactam treatment groups (including anti-staphylococcal penicillins and cephalosporins). The primary outcome was overall treatment failure (30-day all-cause mortality and/or 90-day relapse). Of 335 patients, 74 (22.09%) received benzylpenicillin and 261 (77.91%) received a non-benzylpenicillin beta-lactam. While rates of overall treatment failure (13.51% vs. 17.24%; P = 0.45) and occurrence of adverse drug events (6.76% vs. 7.66%; P = 0.79) were comparable to non-benzylpenicillin beta-lactams, benzylpenicillin showed faster microbiological clearance [3.00 days (IQR, 2.00-4.00 days) vs. 4.00 days (IQR, 3.00-5.00 days); P = 0.03] and fewer persistent infections (22.97% vs. 36.02%; P = 0.04), suggesting potential to improve patient outcomes. We also found that unknown source (aOR 4.63, 95% CI 1.47-14.64; P < 0.01) was associated with treatment failure, while review by Infectious Disease (ID) specialists (aOR 0.30, 95% CI 0.12-0.73; P = 0.01) was protective, stressing the importance of early ID referral and thorough source identification. This study highlights benzylpenicillin as an effective treatment for PSSA BSI.

Contact Precautions for Preventing Methicillin-Resistant Staphylococcus Aureus in Pediatric Healthcare Settings: Pros, Cons, and Future Actions

Although contact precautions (CP) have proven effective in protecting patients and healthcare providers and preventing the transmission of methicillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities, pediatric patients under CP may experience unintended effects, including psychosocial stress and limited access to developmentally appropriate activities. Modifying or discontinuing the routine use of CP based on risk assessment results may enhance their overall benefits. Facilities that opt to modify or cease the routine use of CP should base their decisions on (1) compliance with the local regulations related to MRSA; (2) institutional compliance with CP for patients with MRSA infection and/or colonization, and (3) assessment of local MRSA data. Irrespective of any changes, all pediatric facilities should conduct ongoing assessments of MRSA-specific risks and monitor compliance with infection control practices. The results of these activities should guide the optimal use of CP to prevent MRSA infections among hospitalized pediatric patients.

Management of Staphylococcus aureus Bacteremia: A Review

Importance

Staphylococcus aureus, a gram-positive bacterium, is the leading cause of death from bacteremia worldwide, with a case fatality rate of 15% to 30% and an estimated 300 000 deaths per year.

Observations

Staphylococcus aureus bacteremia causes metastatic infection in more than one-third of cases, including endocarditis (≈12%), septic arthritis (7%), vertebral osteomyelitis (≈4%), spinal epidural abscess, psoas abscess, splenic abscess, septic pulmonary emboli, and seeding of implantable medical devices. Patients with S aureus bacteremia commonly present with fever or symptoms from metastatic infection, such as pain in the back, joints, abdomen or extremities, and/or change in mental status. Risk factors include intravascular devices such as implantable cardiac devices and dialysis vascular catheters, recent surgical procedures, injection drug use, diabetes, and previous S aureus infection. Staphylococcus aureus bacteremia is detected with blood cultures. Prolonged S aureus bacteremia (≥48 hours) is associated with a 90-day mortality risk of 39%. All patients with S aureus bacteremia should undergo transthoracic echocardiography; transesophageal echocardiography should be performed in patients at high risk for endocarditis, such as those with persistent bacteremia, persistent fever, metastatic infection foci, or implantable cardiac devices. Other imaging modalities, such as computed tomography or magnetic resonance imaging, should be performed based on symptoms and localizing signs of metastatic infection. Staphylococcus aureus is categorized as methicillin-susceptible (MSSA) or methicillin-resistant (MRSA) based on susceptibility to β-lactam antibiotics. Initial treatment for S aureus bacteremia typically includes antibiotics active against MRSA such as vancomycin or daptomycin. Once antibiotic susceptibility results are available, antibiotics should be adjusted. Cefazolin or antistaphylococcal penicillins should be used for MSSA and vancomycin, daptomycin, or ceftobiprole for MRSA. Phase 3 trials for S aureus bacteremia demonstrated noninferiority of daptomycin to standard of care (treatment success, 53/120 [44%] vs 48/115 [42%]) and noninferiority of ceftobiprole to daptomycin (treatment success, 132/189 [70%] vs 136/198 [69%]). Source control is a critical component of treating S aureus bacteremia and may include removal of infected intravascular or implanted devices, drainage of abscesses, and surgical debridement.

Conclusions and relevance

Staphylococcus aureus bacteremia has a case fatality rate of 15% to 30% and causes 300 000 deaths per year worldwide. Empirical antibiotic treatment should include vancomycin or daptomycin, which are active against MRSA. Once S aureus susceptibilities are known, MSSA should be treated with cefazolin or an antistaphylococcal penicillin. Additional clinical management consists of identifying sites of metastatic infection and pursuing source control for identified foci of infection.

Clinical revenues of selective use of [18F]-FDG-PET/CT scanning in the management of Staphylococcus aureus bacteremia

PURPOSE

Although [18F]-FDG-PET/CT scanning (PET/CT) is recommended for managing Staphylococcus aureus bacteremia (SAB), its added value remains debated. This study investigated the clinical revenues of selective PET/CT use in SAB by considering three consequence-categories: detection of new infection foci, performance of new interventions, and alterations in antimicrobial therapy.

METHODS

All adult patients with ≥ 1 blood culture (BC) positive with Staphylococcus aureus admitted in a Dutch academic center between 201711 and 202311 were identified. Standard practice was to order PET/CT for patients with community acquired SAB and/or positive BCs after ≥ 48 h of treatment, or if multiple foci, or persistent fever, or endocarditis were present. Clinical- and laboratory data were obtained from electronic health records. Numbers-needed-to-scan (NNT-scan) were calculated for each consequence-category. Regression analyses were performed to identify variables correlated with consequence-bearing PET/CT.

RESULTS

Of 397 SAB patients, 143 (36%) underwent PET/CT. This led to detection of new foci in 73/143 patients (NNT-scan ≈ 2), new interventions in 33/143 patients (NNT-scan ≈ 4), and a change in antimicrobial therapy in 44/143 patients (NNT-scan ≈ 3). A CRP > 200 mg/L at presentation and positive follow-up BCs at 48 h were independently associated with interventions following PET/CT (adjusted OR and 95%CI 3.2 (1.2-8.3) and 2.6 (1.0-6.7) respectively). PET/CT results instigated changes in antimicrobial therapy predominantly in patients < 65 years and those with a CRP < 100 at presentation.

CONCLUSIONS

Selective PET/CT ordering in real-life practice resulted in a relatively low NNT-scan across all consequence-categories. Further research is warranted to optimize patient selection for PET/CT using clinical parameters or profiles.

Dual Delivery of Cells and Bioactive Molecules for Wound Healing Applications

Chronic wounds not only cause significant patient morbidity but also impose a substantial economic burden on the healthcare system. The primary barriers to wound healing include a deficiency of key modulatory factors needed to progress beyond the stalled inflammatory phase and an increased susceptibility to infections. While antimicrobial agents have traditionally been used to treat infections, stem cells have recently emerged as a promising therapy due to their regenerative properties, including the secretion of cytokines and immunomodulators that support wound healing. This study aims to develop an advanced dual-delivery system integrating stem cells and antibiotics. Stem cells have previously been delivered by encapsulation in gelatin methacrylate (GelMA) hydrogels. To explore a more effective delivery method, GelMA was processed into microparticles (MP). Compared to a bulk GelMA hydrogel (HG) encapsulation, GelMA MP supported greater cell growth and enhanced in vitro wound healing activity of human mesenchymal stem cells (hMSCs), likely due to a larger surface area for cell attachment and improved nutrient exchange. To incorporate antimicrobial properties, the broad-spectrum antibiotics penicillin/streptomycin (PS) were loaded into a bulk GelMA hydrogel, which was then cryo-milled into MPs to serve as carriers for hMSCs. To achieve a more sustained antibiotic release, gelatin nanoparticles (NP) were used as carriers for PS. PS was either incorporated during NP synthesis (NP+PS(S)) or absorbed into NP after synthesis (NP+PS(A)). MPs containing PS, NP+PS(S), or NP+PS(A) were tested for their cell carrier functions and antibacterial activities. The incorporation of PS did not compromise the cell-carrying function of MP configurations. The anti-S. aureus activity was detected in conditioned media from MPs for up to eight days-four days longer than from bulk HG containing PS. Notably, the presence of hMSCs prolonged the antimicrobial activity of MPs, suggesting a synergistic effect between stem cells and antibiotics. PS loaded via synthesis (NP+PS(S)) exhibited a delayed initial release, whereas PS loaded via absorption (NP+PS(A)) provided a more immediate release, with potential for sustained delivery. This study demonstrates the feasibility of a dual-delivery system integrating thera.

Unfavorable Outcomes and Their Risk Factors in Hospitalized Patients with Staphylococcus aureus Bacteremia in the US: A Multicenter Retrospective Cohort Study, 2020-2022

Background: In the US, 120,000 cases of Staphylococcus aureus bacteremia (SAB) occur annually. Apart from mortality, little is known about other unfavorable outcomes (UOs). We developed a multifaceted definition for UOs in SAB and examined their incidence and predictors. Methods: We conducted a multicenter (~300 hospitals) retrospective cohort study between 2020 and 2022 of adult hospitalized patients with at least one blood culture (BC) positive for S. aureus. UOs were any of the following: hospital mortality, antibiotic escalation, persistently positive BCs, prolonged post-infection length of stay (LOS), 30-day readmission, and disease worsening. We compared the group with UOs to favorable outcomes (FOs). Regression models identified predictors of UOs. Results: Among 4080 patients with SAB, 2427 (59.5%) experienced a UO, most commonly 30-day readmission (42.0%) and antibiotic escalation (37.7%). Those with UOs more frequently had septic shock at admission (5.7% vs. 1.2%), requiring the ICU (18.8% vs. 14.7%) and dialysis (4.4% vs. 1.9%) prior to SAB onset. Community-onset SAB predominated in both groups, with more complicated SAB in the UO group (39.8% vs. 22.3%). Vancomycin use was similar, while daptomycin was more common in the UO group (8.5% vs. 3.0%). Variables with the highest odds ratios predicting a UO were septic shock on admission (3.498, 95% CI 2.145, 5.704), empiric daptomycin (2.723, 95% CI 1.943, 3.821), and complicated SAB (2.476, 95% CI 2.047, 2.994). Conclusions: UOs occur frequently in the setting of SAB. A broader perspective exploring issues other than mortality demonstrates the substantial implications of SAB both for patients and healthcare systems. Select clinical variables are associated with UOs, some of which may not be modifiable.

Evidence that staphylococcal superantigens promote within-patient bacterial persistence following post-operative surgical site infection

Staphylococcus aureus is a predominant cause of post-operative surgical site infections and persistent bacteremia. Here, we describe a patient who experienced three episodes of S. aureus infection over a period of 4 months following a total knee arthroplasty. The initial bloodstream isolate (SAB-0429) was a clonal complex 5 (CC5) and methicillin-resistant S. aureus (MRSA), whereas two subsequent isolates (SAB-0485 and SAB-0495) were CC5 isolates but methicillin-sensitive S. aureus. The two latter isolates harbored a plasmid encoding three superantigen genes that were not present in the primary MRSA isolate. SAB-0485 and SAB-0495 both expressed the plasmid-encoded staphylococcal enterotoxin R exotoxin and demonstrated increased superantigen activity compared with SAB-0429. Compared to SAB-0429, the latter isolates also demonstrated an increased bacterial burden in a mouse bacteremia model that was dependent on increased interferon-γ production. Curing of the plasmid from SAB-0485 reduced this virulence phenotype. These findings suggest that the superantigen exotoxins may provide a selective advantage in chronic post-surgical infections.IMPORTANCEIn this study, we investigated bacterial isolates from a patient who experienced three recurrent S. aureus infections over a 4 month period following total knee arthroplasty. Genomic and phenotypic characterization of these isolates revealed that they all belonged to clonal complex 5, yet the latter two strains contained an additional plasmid encoding superantigen exotoxins. Subsequent experimental infection experiments in mice demonstrated that the plasmid-encoded superantigens exacerbated bacteremia by promoting liver abscess formation. These experiments suggest that despite appropriate antibiotic therapy, bacterial superantigens may be able to promote persistent infection following post-surgery.

Epidemiological profile and antimicrobial resistance trends of Staphylococcus aureus in Chinese pediatric intensive care units from 2016 to 2022: a multi-center retrospective study

OBJECTIVE

This study aimed to analyze the profiles and evolution of Staphylococcus aureus in the pediatric intensive care units (PICUs) of 17 hospitals in China from 2016 to 2022.

METHODS

Susceptibility testing was performed to bacterial strains with a uniform monitoring protocol, which was provided by the US Clinical and Laboratory Standards Institute (CLSI) and used by the China Antimicrobial Surveillance Network (CHINET). The results were interpreted in accordance with the performance standards for antimicrobial susceptibility testing issued by the US Clinical and Laboratory Standards Institute.

RESULTS

Twenty-six thousand six hundred thirteen bacterial strains were isolated from 17 PICUs in China from 2016 to 2022, 3,147 of which were Staphylococcus aureus, ranking second among etiological agents of infections from PICUs. In 2022, Staphylococcus aureus had the highest detection rate, being 36.19%. And in 2021, MRSA had the highest detection rate, being 10.35% in Staphylococcus aureus. There were statistically significant differences in the annual detection rate of gram-positive bacteria, Staphylococcus aureus and MRSA between the years from 2016 to 2022 (P < 0.05). More males were found with Staphylococcus aureus or methicillin-resistant Staphylococcus aureus, but there were no statistical differences in gender distribution between any two years (P < 0.05). The top 3 highest detection rate of Staphylococcus aureus in age groups were infants (1244, 39.7%), toddlers (741, 23.7%), and children at school age and older (731, 23.4%). For MRSA, The top 3 in age groups were infants (91, 38.9%), children at school age and older (87, 29.1%), and toddlers (48, 20.5%). The detection rate of Staphylococcus aureus was statistically different in the distribution of age stratification (P < 0.05). There was no statistically significant difference in these two aspects of MRSA (P > 0.05). The top 3 highest detection rate of Staphylococcus aureus in infected sites were the lower respiratory tract (2,552, 81.7%), bloodstream (217, 6.5%), and skin wounds (110, 3.9%). For MRSA, The top 3 in infected sites were the lower respiratory tract (156, 77.9%), skin wounds (47, 8.8%), and bloodstream (15, 6.6%). The detection rate of Staphylococcus aureus and MRSA was statistically different in the distribution of infected sites (P < 0.05). All the strains of Staphylococcus aureus were sensitive to tigecycline, nitrofurantoin, vancomycin, and linezolid. The resistant rate of Staphylococcus aureus, to penicillin G was as high as 87.5% at least, to erythromycin was as high as 51.8% at least, to benzocillin was as high as 38.0% at least, to cefoxitin was as high as 35.5% at least, and to clindamycin was as high as 32.7% at least. All the strains of MRSA were sensitive to vancomycin, linezolid, quinupristin/dalfopristin, and tigecycline. Of these 234 strains of MRSA, 179 (76.5%) were resistant to erythromycin, 116 (49.6%) to clindamycin, 39 (16.7%) to tetracycline, 29 (12.4%) to levofloxacin, 27 (11.5%) to ciprofloxacin, 27 (11.5%) to moxifloxacin, 14 (6.0%) to TMP-SMX, eight (3.4%) to rifampicin, and six (2.6%) to gentamicin.

CONCLUSIONS

Staphylococcus aureus is the most common gram-positive bacterium in PICUs. Infants are most likely to be infected by Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. And the lower respiratory tract is the most common infected site of Staphylococcus aureus. Staphylococcus aureus has a high resistant rates to commonly used antimicriobials in pediatrics, but no strains resistant to vancomycin and/or linezolid were found. When considering Staphylococcus aureus infection clinically, it is necessary to select antimicrobials reasonably based on the patient's age, infected site and local epidemiological characteristics.

Molecular characterization of methicillin-susceptible/resistant Staphylococcus aureus from bloodstream infections in northern Japan: The dominance of CC1-MRSA-IV, the emergence of human-associated ST398 and livestock-associated CC20 and CC97 MSSA

OBJECTIVES

Staphylococcus aureus (S. aureus) is a major cause of bloodstream infections. The recent epidemiological features and antimicrobial resistance trend were analysed for methicillin-resistant and susceptible S. aureus (MRSA/MSSA) isolates from blood samples in people from northern Japan.

METHODS

The S. aureus isolates from blood culture were screened by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) and genotyped by the schemes of multilocus sequence typing (MLST), coa, agr, spa, and SCCmec types. Antimicrobial resistance genes and virulence factors were detected by multiplex/uniplex polymerase chain reaction (PCR). Antimicrobial susceptibility was examined using a broth microdilution test.

RESULTS

A total of 301 isolates (163 MRSA and 138 MSSA) were isolated from bloodstream infections in 2023 (from April to December). The MRSA isolates were classified into three groups, that is, clonal complexes (CC)1-SCCmec-IV (CC1-IV) (52%), CC5-II (36%), and CC8-IV (12%). The prevalence of CC1 was significantly higher than those in our previous studies (2017-2021). Four CC8-IVa isolates with PVL genes on ΦSa2usa were considered to be the USA300 clone (sequence type [ST]8/spa-t008/coa IIIa/agr I) or its variants that were genotyped as those closely related to ST8/t008 or lacking arginine catabolic mobile element (ACME). In contrast, MSSA was genetically highly divergent and classified into 22 STs, with CC1 (ST1 and ST188) being the most common (25%). It was notable that 29 MSSA isolates (21%) were classified into livestock-associated (LA) genotypes, ST20, ST97, and CC398 (ST398 and ST291). Genetic characterization of the CC398 isolates suggested that these belong to human-adapted MSSA clones.

CONCLUSIONS

The present study revealed the increasing trend of CC1 MRSA surpassing CC5, and the emergence of MSSA representing human-adapted CC398, and LA types ST97 and ST20 from bloodstream infections in people in Japan. © 2024 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy.

Subsequent bacteremia associated with intravascular catheter colonization with Staphylococcus aureus, Gram-negative rods, and Candida species in children

Subsequent bacteremia developed in 14 % of patients with positive catheter tip cultures but concurrent negative blood cultures. The occurrence of subsequent bacteremia did not differ significantly by pathogens (Staphylococcus aureus, Gram-negative rods [GNR], and Candida spp.). Mortality was higher in patients with GNR and Candida spp. than with S. aureus.

Recreational Facilities as Reservoirs for Multidrug-Resistant Staphylococcus aureus

Antibiotic-resistant pathogens in public settings present a growing risk to human health. Staphylococcus aureus often asymptomatically colonizes human skin, while virulent strains cause soft tissue infections, osteomyelitis, endocarditis, and are associated with cystic fibrosis. Here we investigated the presence and distribution of multidrug-resistant S. aureus on exercise equipment in university recreation facilities. Equipment sampled included barbells (n = 10), dumbbell handles (n = 15), kettle bell handles (n = 5), ellipticals (n = 5), treadmills (n = 5), cable attachments (n = 5). Mannitol salt agar, CHROMagar-MRSA, Gram staining and latex agglutination testing were useds to isolate and identify S. aureus, including methicillin-resistant S. aureus. Kirby-Bauer disc-diffusion assay was utilized to determine antibiotic susceptibility profiles. Results show 42% of 456 S. aureus isolates from 45 different equipment surfaces were ampicillin resistant. Of 60 representative ampicillin-resistant isolates, 92% were resistant to additional antibiotics with the majority resistant to erythromycin (40%) and sulfisoxazole (75%). Multidrug resistance to three or more drugs was observed in 73% of the ampicillin-resistant subpopulation. These results indicate recreational facilities may serve as reservoirs for multi-drug resistant S. aureus including methicillin-resistant S. aureus (MRSA) and regular disinfection of equipment is warranted for safeguarding public health.

Efficacy of Staphylococcus aureus nasal decolonization at hospital admission on reduction of any infections within 90 days - a systematic review and meta-analysis

Infections with Staphylococcus aureus are associated with excess mortality and costs. Simple interventions, such as decolonization protocols, might help to reduce subsequent infections, especially in settings in which S. aureus is of major clinical relevance, such as healthcare-associated infections. The aim of this research was to determine whether S. aureus decolonization protocols, using a nasal ointment and applied at hospital admission, reduce the risk of infection. MEDLINE, EMBASE and clinicaltrials.gov were searched for all randomized controlled trials investigating the use of nasal ointments for decolonization for patients at hospital admission and reporting on infections within 90 days. Data were pooled as risk ratios using a random-effects model. The Cochrane RoB 2 tool and GRADE were used to assess the risk of bias and quality of evidence. Four (0.5%) of 833 screened studies with a total of 4150 patients met eligibility criteria. The overall certainty of evidence ranged from low to moderate across outcomes. Nasal S. aureus decolonization probably reduces infections (6.9% vs 9.5%; rate ratio (RR): 0.73 (95% confidence interval (CI) 0.57; 0.93)) and may increase microbiological eradication (82.7% vs 55.2%; RR: 1.80 (95% CI 0.73; 4.44)) compared with placebo. It may not reduce mortality (2.5 vs 2.4; RR: 1.02 (95% CI 0.67; 1.54)) but also not lead to increased adverse effects (0.7% vs 0.6%; RR: 1.01 (95% CI 0.45; 2.30)). Results were consistent across subgroups and sensitivity analyses. In conclusion, nasal decolonization at acute-care hospital admission probably reduces the risk of infections and may result in a large increase in microbiological eradication. It may not reduce mortality and also not result in an increased number of adverse events.

Early cytokine signatures and clinical phenotypes discriminate persistent from resolving MRSA bacteremia

BACKGROUND

Staphylococcus aureus bacteremia (SAB) is a prevalent life-threatening infection often caused by methicillin-resistant S. aureus (MRSA). Up to 30% of SAB patients fail to clear infection even with gold-standard anti-MRSA antibiotics. This phenomenon is termed antibiotic-persistent MRSA bacteremia (APMB). The mechanisms driving APMB are complex and involve host phenotypes significantly impacting the immune response. Thus, defining early immune signatures and clinical phenotypes that differentiate APMB from antibiotic resolving (AR)MB could aid therapeutic success.

METHODS

We assessed 38 circulating cytokines and chemokines using affinity proteomics in 74 matched pairs of vancomycin-treated SAB cases identified as ARMB or APMB after 5 days of blood culture.

RESULTS

Unsupervised hierarchical clustering segregated APMB from ARMB based on differential levels of IL-10, IL-12p40, IL-13, CCL4, and TGFα. Additionally, CXCL1, CCL22 and IL-17A significantly differed between APMB and ARMB when correlated with diabetes, dialysis, metastatic infection, or cardiac vegetation. Combining immune signatures with these relevant clinical phenotypes sharply increased accuracy of discriminating APMB outcome to 79.1% via logistic regression modeling. Finally, classification-regression tree analysis revealed explicit analyte thresholds associated with APMB outcome at presentation especially in patients with metastatic infection.

CONCLUSIONS

Collectively, this study identifies previously unrecognized cytokine and chemokine signatures that distinguish APMB and ARMB at presentation and in the context of host clinical characteristics associated with increased disease severity. Validation of a biomarker signature that accurately predicts outcomes could guide early therapeutic strategies and interventions to reduce risks of persistent SAB that are associated with worsened morbidity and mortality.

Inhibition of proton sensor GPR68 suppresses endothelial dysfunction and acute lung injury caused by Staphylococcus aureus bacterial particles

Lung bacterial infections, including hospital-acquired pneumonia, remain a serious problem for public health. Endothelial cell (EC) exposure to heat-killed Staphylococcus aureus (HKSA) represents a clinical scenario of high titers of killed bacterial particles present in the host after antibiotic therapy, which triggers inflammatory cascades, cytokine storms, and EC dysfunction leading to acute lung injury (ALI). GPR68 is a member of the proton-sensing G protein-coupled receptor family. Acting as a pH sensor, GPR68 becomes activated upon pH reduction and contributes to pathologic cell responses by activating ER stress and unfolded protein response. This study investigated the role of GPR68 in HKSA-induced EC dysfunction and HKSA-induced ALI. HKSA robustly increased GPR68 mRNA levels in human pulmonary EC and directly stimulated GPR68 activity. A selective GPR68 small molecule inhibitor, OGM-8345, attenuated HKSA-induced EC permeability and protected cell junction integrity. OGM-8345 inhibited HKSA-induced activation of inflammatory genes TNF-α, IL-6, IL-8, IL-1β, and CXCL5 and decreased cytokine secretion by HKSA-challenged EC. Co-treatment with the GPR68 activator Ogerin or medium acidification to pH 6.5 augmented HKSA-induced EC dysfunction, which was rescued by OGM-8345. Intratracheal HKSA injection increased vascular leak and lung inflammation in mice which were monitored by lung Evans blue extravasation, increased cell and protein count in bronchoalveolar lavage, and mRNA expression of inflammatory genes. ALI and barrier dysfunction was attenuated by OGM-8345. We show for the first time the role of GPR68 in mediating HKSA-induced lung injury and the strong potential for OGM-8345 as a therapeutic treatment of bacterial pathogen-induced ALI associated with tissue acidification.

Piceatannol and its analogues alleviate Staphylococcus aureus pathogenesis by targeting β-lactamase biofilms and α-hemolysin

β-Lactamases, biofilms and toxins pose challenges for combating S. aureus infection. Thus, identifying inhibitors that can restore bacterial sensitivity to antibiotics, destroy biofilms, and antitoxins is a promising way to develop alternative agents. In this study, we found that piceatannol (pit), along with its analogues resveratrol (ret) and pterostilbene (pts) bind with β-lactamase to inhibit its activity, and 96TYR, 58ILE and 66LYS were identified as the critical binding residues. Pit and pts reduced the ampicillin (Amp) and gentamicin (Gm) MICs against S. aureus and enhanced the bactericidal ability of Amp. Pit and its analogues inhibited the formation of S. aureus USA300. In addition, the pit analogues bound with α-hemolysin and suppressed the hemolysis activity of the bacterial culture supernatant. The mechanism analysis revealed that pit exhibited multiple potential binding modes with α-hemolysin. Pit significantly decreased the cytotoxicity and the adherence effect mediated by S. aureus and increased the survival rate of Galleria mellonella that infected with S. aureus, the pathological tissue damage of Galleria mellonella was alleviated by treatment with pit alone or in combination with Amp. Taken together, our findings identify promising compounds for the development of S. aureus infection inhibitors.

Staphylococcus aureus in Inflammation and Pain: Update on Pathologic Mechanisms

Staphylococcus aureus (S. aureus) is a Gram-positive bacterium of significant clinical importance, known for its versatility and ability to cause a wide array of infections, such as osteoarticular, pulmonary, cardiovascular, device-related, and hospital-acquired infections. This review describes the most recent evidence of the pathogenic potential of S. aureus, which is commonly part of the human microbiota but can lead to severe infections. The prevalence of pathogenic S. aureus in hospital and community settings contributes to substantial morbidity and mortality, particularly in individuals with compromised immune systems. The immunopathogenesis of S. aureus infections involves intricate interactions with the host immune and non-immune cells, characterized by various virulence factors that facilitate adherence, invasion, and evasion of the host's defenses. This review highlights the complexity of S. aureus infections, ranging from mild to life-threatening conditions, and underscores the growing public health concern posed by multidrug-resistant strains, including methicillin-resistant S. aureus (MRSA). This article aims to provide an updated perspective on S. aureus-related infections, highlighting the main diseases linked to this pathogen, how the different cell types, virulence factors, and signaling molecules are involved in the immunopathogenesis, and the future perspectives to overcome the current challenges to treat the affected individuals.

Exploring combination treatment options for persistent methicillin-susceptible Staphylococcus aureus bacteremia

PURPOSE

This review explores the management of persistent methicillin-susceptible Staphylococcus aureus bacteremia (SAB), emphasizing the importance of timely intervention due to SAB's association with metastatic dissemination, relapse, and mortality.

SUMMARY

The literature analysis first delves into risk factors for persistent SAB, highlighting the need for effective treatment strategies. The subsequent focus is on combination strategies for persistent SAB. Daptomycin, ertapenem, ceftaroline, fosfomycin, rifampin, and gentamicin are explored as adjuncts to cefazolin or antistaphylococcal penicillins. Daptomycin combination therapy is assessed through in vivo and clinical studies, indicating potential benefits, especially with higher-risk sources of infection. Ertapenem combination therapy has been demonstrated to have a synergistic effect with cefazolin, presenting a viable salvage option. Rifampin's ability to penetrate biofilm is examined, with discussion of inconclusive evidence on mortality benefits. The review also considers stewardship implications, discussing concerns such as resistance emergence, adverse events, and increased costs associated with combination therapy. Mathematical models suggest combination therapy as an effective approach to prevent resistance. Adverse events vary with each combination, and duration of therapy remains diverse across studies in the absence of well-established dosing guidelines.

CONCLUSION

The review provides a thorough exploration of the literature on treatment of persistent SAB, underscoring the need for evidence-based guidelines, further studies, and clinical judgment in tailoring treatment strategies. The multifaceted analysis contributes valuable insights for clinicians managing this challenging condition.

Prevalence of Methicillin-Resistant Staphylococcus aureus in Livestock in Japan: A Systematic Review and Meta-Analysis

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is an important health issue that is estimated to have caused 130,000 deaths worldwide in 2021. As more instances of cross-species transmission of MRSA have been reported, concerns have been raised regarding the spread of livestock-associated MRSA to humans. The prevalence of MRSA in livestock varies globally. This study systematically reviews the prevalence of MRSA at the farm and animal levels in Japan. Methods: Relevant studies published in English or Japanese between 2000 and 2023 were retrieved from four databases. Pooled prevalences at the farm and animal levels in Japanese farms were calculated using a random-effects model. Subgroup and meta-regression analyses were also performed to explore sources of heterogeneity. Results: The 13 studies included in this meta-analysis yielded an MRSA prevalence of 3.54% (95% confidence interval [CI] 0.65-8.30%) at the individual pig level, 13.07% (95% CI 5.42-23.04%) at the pig farm level, 0.0% (95% CI 0.00-0.04%) at the individual cattle level, and 0% (95% CI 0.00-0.44%) at the individual chicken level. A significant increase in MRSA prevalence over time was evident at the individual pig level by both subgroup analysis (p = 0.020) and meta-regression (p = 0.019). Conclusions: Our results indicated that the proportion of pigs that can be a source of MRSA infection in humans has been steadily increasing in Japan. Despite some limitations, our findings strongly imply a need for more attention to pig-to-human MRSA transmission in Japan.

Antimicrobial activity of adipose-derived mesenchymal stromal cell secretome against methicillin-resistant Staphylococcus aureus

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is still a growing concern in the field of antimicrobial resistance due to its resistance to conventional antibiotics and its association with high mortality rates. Mesenchymal stromal cells (MSCs) have been shown as a promising and attractive alternative treatment for bacterial infections, due to their antibacterial properties and potential to bypass traditional resistance mechanisms. This study aims to shed light on the antibacterial potential of adipose-derived mesenchymal stromal cell (AD-MSC) secretome against clinical isolates of Staphylococcus spp., including MRSA strains.

METHODS

Using the Kirby-Bauer disk diffusion method, broth microdilution assays, and colony-forming unit (CFU) counting, the antibacterial activity of AD-MSC secretome was assessed. These tests were first conducted on Staphylococcus (S.) aureus ATCC 25923, then on 73 clinical isolates including MRSA strains. Further molecular analysis was performed to identify resistant genes in MRSA isolates.

RESULTS

The AD-MSC secretome demonstrated significant antibacterial activity against S. aureus ATCC with a 32 mm inhibition zone. 96% of the collected staphylococcal clinical isolates showed susceptibility to the secretome with 87.5% inhibition observed in MRSA isolates, along with 100% in MSSA, MSSE, and MRSE strains. Molecular analysis revealed that MRSA strains resistant to the secretome harbored mecA, ermA, and ermB genes. Additionally, the mecA-negative MRSA strains remained susceptible to the secretome, suggesting alternative resistance mechanisms.

CONCLUSION

These findings emphasize the ability of AD-MSCs secretome as a promising alternative for treating antibiotic-resistant infections, with potential applications in combating MRSA. However, further research is required to explore its clinical applications as a complementary or standalone therapy for resistant infections.

Early initiation of ceftaroline-based combination therapy for methicillin-resistant Staphylococcus aureus bacteremia

PURPOSE

Monotherapy with vancomycin or daptomycin remains guideline-based care for methicillin-resistant Staphylococcus aureus bacteremia (MRSA-B) despite concerns regarding efficacy. Limited data support potential benefit of combination therapy with ceftaroline as initial therapy. We present an assessment of outcomes of patients initiated on early combination therapy for MRSA-B.

METHODS

This was a single-center, retrospective study of adult patients admitted with MRSA-B between July 1, 2017 and April 31, 2023. During this period, there was a change in institutional practice from routine administration of monotherapy to initial combination therapy for most patients with MRSA-B. Combination therapy included vancomycin or daptomycin plus ceftaroline within 72 h of index blood culture and monotherapy was vancomycin or daptomycin alone. The primary outcome was a composite of persistent bacteremia, 30-day all-cause mortality, and 30-day bacteremia recurrence. Time to microbiological cure and safety outcomes were assessed. All outcomes were assessed using propensity score-weighted logistic regression.

RESULTS

Of 213 patients included, 118 received monotherapy (115 vancomycin, 3 daptomycin) and 95 received combination therapy with ceftaroline (76 vancomycin, 19 daptomycin). The mean time from MRSA-positive molecular diagnostic blood culture result to combination therapy was 12.1 h. There was no difference between groups for the primary composite outcome (OR 1.58, 95% CI 0.60, 4.18). Time to microbiological cure was longer with combination therapy (mean difference 1.50 days, 95% CI 0.60, 2.41). Adverse event rates were similar in both groups.

CONCLUSIONS

Early initiation of ceftaroline-based combination therapy did not improve outcomes for patients with MRSA-B in comparison to monotherapy therapy.

Isolated Pulmonary Valve Infective Endocarditis With Persistent Staphylococcus aureus Bacteremia and Rapid Clearance With Ertapenem Plus Cefazolin

Infective endocarditis is an infection of the heart's native or prosthetic valves, often caused by bacteria such as Staphylococcus aureus. Although infective endocarditis most commonly affects the left heart, cases of right-sided infective endocarditis, involving structures like the tricuspid or pulmonary valves, are also noted. Isolated native pulmonary valve infective endocarditis is exceptionally rare. After suspicion, the diagnosis relies on clinical symptoms and signs, imaging, and microbiological evidence. We report an unusual case of isolated pulmonary valve infective endocarditis in a previously healthy 59-year-old man without typical risk factors. He presented with unspecific symptoms such as fever, chills, dizziness, and left shoulder pain. Radiologically, the patient presented small ground-glass opacities in both lungs that aggravated during the first days after hospital admission with multifocal consolidation areas, and later developing bilateral necrotizing pneumonia. Despite adequate antibiotic treatment, the patient developed septic shock and persistent Staphylococcus aureus bacteremia. Given the persistence of such microorganisms in the bloodstream, despite the initial absence of endocardial involvement on transthoracic echocardiography, transesophageal echocardiography was done and revealed a large vegetation on the pulmonary valve with valvular regurgitation. According to Duke's criteria for infective endocarditis, a definite diagnosis was made, once both major clinical criteria were present, namely, typical microorganisms consistent with infective endocarditis from two separate blood cultures and evidence of endocardial involvement. Given the refractory bacteremia, an unusual combination of antibiotic therapy, including ertapenem and cefazolin, was introduced, leading to rapid clearance of bacteremia. This salvage antibiotic regimen was chosen due to the synergy of carbapenem with cefazolin and their potential improved bactericidal activity within biofilms. The patient subsequently required surgical intervention with bioprosthetic pulmonary valve replacement and ultimately achieved near-full recovery after a prolonged hospital stay. This case illustrates the diagnostic and therapeutic challenges of rare right-sided infective endocarditis since the patient presented with non-specific symptoms, without typical risk factors for right-sided infective endocarditis and the initial transthoracic echocardiography showed no valvular vegetations. Furthermore, the persistence of bacteremia despite adequate antibiotic therapy was a clinical challenge and this case highlights the potential efficacy of ertapenem plus cefazolin in treating persistent Staphylococcus aureus infections. It underscores the importance of individualized management in severe cases and the need for ongoing research to optimize treatment strategies for persistent infections.

Risk Factors for Infection-Attributable Mortality in Patients With Staphylococcus aureus Bacteremia: A Competing Risk Analysis

Background

Identifying risk factors for mortality in patients with Staphylococcus aureus bacteremia (SAB) is crucial due to its high fatality. However, data on risk factors for infection-attributable deaths considering competing risk events such as non-infection-attributable deaths remain limited. We performed a competing risk analysis to elucidate risk factors associated with 30-day infection-attributable mortality in a large cohort of patients with SAB.

Methods

This retrospective cohort study included adult patients diagnosed with SAB at a tertiary hospital from August 2008 to December 2019. Competing risk analysis was performed using Fine and Gray models to estimate subdistribution hazard ratios (sHRs) for 30-day infection-attributable death.

Results

Among 1936 patients, 444 (22.9%) died within 30 days. Of these, 338 (76.1%) were infection-attributable and 106 (23.9%) were non-infection-attributable deaths. The multivariable Fine and Gray model identified significant risk factors for 30-day infection-attributable death (sHRs with 95% confidence intervals): an increase in age by 10 years (1.14 [1.02-1.26]), presence of malignancy (1.54 [1.17-2.02]), liver cirrhosis (2.15 [1.56-2.97]), corticosteroid use (1.61 [1.19-2.17]), septic shock (3.28 [1.98-5.42]), elevated C-reactive protein (1.60 [1.19-2.14]), pneumonia (1.81 [1.21-2.72]), persistent bacteremia (1.73 [1.31-2.30]), and failure to remove the eradicable focus (2.40 [1.38-4.19]) or absence of an eradicable focus (1.49 [1.08-2.04]). Except for age and malignancy, these factors were not significantly associated with non-infection-related death.

Conclusions

Specific risk factors for infection-attributable death in patients with SAB were identified, distinct from those for nonattributable death. These findings can aid in the early identification of patients at risk for SAB-attributable mortality.

Immune Checkpoint Molecules as Biomarkers of Staphylococcus aureus Bone Infection and Clinical Outcome

Staphylococcus aureus prosthetic joint infections (PJIs) are broadly considered incurable, and clinical diagnostics that guide conservative vs. aggressive surgical treatments don't exist. Multi-omics studies in a humanized NSG-SGM3 BLT mouse model demonstrate human T cells: 1) are remarkably heterogenous in gene expression and numbers, and 2) exist as a mixed population of activated, progenitor-exhausted, and terminally-exhausted Th1/Th17 cells with increased expression of immune checkpoint proteins (LAG3, TIM-3). Importantly, these proteins are upregulated in the serum and the bone marrow of S. aureus PJI patients. A multiparametric nomogram combining high serum immune checkpoint protein levels with low proinflammatory cytokine levels (IFN-γ, IL-2, TNF-α, IL-17) revealed that TIM-3 was highly predictive of adverse disease outcomes (AUC=0.89). Hence, T cell impairment in the form of immune checkpoint expression and exhaustion could be a functional biomarker for S. aureus PJI disease outcome, and blockade of checkpoint proteins could potentially improve outcomes following surgery.

Strategies to reduce 28-day mortality in adult patients with bacteremia in the emergency department

BACKGROUND

Bacteremia, a common emergency department presentation, has a high burden of mortality, cost and morbidity. We aimed to identify areas for potential improvement in emergency department bacteremia management.

METHODS

This retrospective cohort study included adults with bacteremia in an emergency department in 2019 and 2022. The primary outcome was 28-day mortality. Descriptive analyses evaluated demographics, comorbidities and clinical characteristics. Univariate and multivariate analyses identified mortality predictors.

RESULTS

Overall, 433 patients were included [217 males (50.1%), mean ± SD age: 74.1 ± 15.2 years]. The 28-day mortality rate was 15.2% (n = 66). In univariate analysis, age ≥ 70 years, arrival by ambulance, arrhythmia, congestive heart failure, recent steroid use, hypotension (< 90/60 mmHg), mechanical ventilation, cardiac arrest, intensive care unit (ICU) admission, intravenous antibiotics, pneumonia as bacteremia source, non-urinary tract infections, no infectious disease consultation, no antibiotic adjustment and no control blood cultures were significantly associated with 28-day mortality (p < 0.05). Malignancy showed a statistical trend (0.05 < p < 0.15). The above-stated sixteen variables, identified in univariate analysis, were assessed via multivariate analysis. Primarily, clinical relevance and, secondarily, statistical significance were used for multivariate model creation to prioritize pertinent variables. Five risk factors, significantly associated with mortality (p < 0.05), were included in the model: ICU admission [adjusted OR (95% CI): 6.03 (3.08-11.81)], pneumonia as bacteremia source [4.94 (2.62-9.32)], age ≥ 70 [3.16 (1.39-7.17)], hypotension [2.12 (1.02-4.40)], and no infectious disease consultation [2.02 (1.08-3.78)]). Surprisingly, initial antibiotic administration within 6 h, inappropriate initial antibiotic regimen and type of bacteria (Gram-negative, Gram-positive) were non-significant (p > 0.05).

CONCLUSIONS

We identified significant mortality predictors among emergency department patients presenting with bacteremia. Referral to an infectious disease physician is the only modifiable strategy to decrease 28-day mortality with long-term effect and should be prioritized.

Differences in oxazolidinone resistance mechanisms and small colony variants emergence of Staphylococcus aureus induced in an in vitro resistance development model

Invasive Staphylococcus aureus infections are associated with a high burden of disease, case fatality rate and healthcare costs. Oxazolidinones such as linezolid and tedizolid are considered potential treatment choices for conditions involving methicillin resistance or penicillin allergies. Additionally, they are being investigated as potential inhibitors of toxins in toxin-mediated diseases. In this study, linezolid and tedizolid were evaluated in an in vitro resistance development model for induction of resistance in S. aureus. Whole genome sequencing was conducted to elucidate resistance mechanisms through the identification of causal mutations. After inducing resistance to both linezolid and tedizolid, several partially novel single nucleotide variants (SNVs) were detected in the rplC gene, which encodes the 50S ribosome protein L3 in S. aureus. These SNVs were found to decrease the binding affinity, potentially serving as the underlying cause for oxazolidinone resistance. Furthermore, in opposite to linezolid we were able to induce phenotypically small colony variants of S. aureus after induction of resistance with tedizolid for the first time in literature. In summary, even if different antibiotic concentrations were required and SNVs were detected, the principal capacity of S. aureus to develop resistance to oxazolidinones seems to differ between linezolid and tedizolid in-vivo but not in vitro. Stepwise induction of resistance seems to be a time and cost-effective tool for assessing resistance evolution. Inducted-resistant strains should be examined and documented for epidemiological reasons, if MICs start to rise or oxazolidinone-resistant S. aureus outbreaks become more frequent.

Novel Epigallocatechin Gallate (EGCG) Analogs with Improved Biochemical Properties for Targeting Extracellular and Intracellular Staphylococcus aureus

Staphylococcus aureus is a leading cause of bloodstream infection (SAB), with up to 30% mortality. Despite treatment with standard antibiotics, one in three patients develops a persistent infection, which portends a five-fold increase in the risk of death. Persistent SAB has been attributed in part to the inability of antistaphylococcal antibiotics to eradicate intracellular S. aureus surviving inside macrophages. (-)- Epigallocatechin gallate (EGCG) is a catechin found in green tea that has been widely studied for its broad biological activities, ranging from anticancer to antibacterial activity. However, EGCG is greatly limited by its poor drug-like properties in terms of stability, membrane permeability, and bioavailability. In this study, we established through a series of in vitro experiments that structural modifications of EGCG enhanced drug-like properties while maintaining or improving its antistaphylococcal activity. Our lead EGCG analogs (MCC-1 and MCC-2) showed improved biochemical properties along with increased potency against extracellular S. aureus and restored susceptibility of β-lactam agents to methicillin-resistant S. aureus (MRSA). Importantly, the lead analogs but not EGCG potentiated macrophage- and antibiotic-mediated clearance of intracellular bacteria. Overall, EGCG analogs showed promise for further development as adjunctive therapy candidates for the treatment of SAB.

Building the Future of Infectious Diseases: A Call to Action for Quality Improvement Research and Measurement

Quality is central to value-based care, and measurement is essential for assessing performance and understanding improvement over time. Both value-based care and methods for quality measurement are evolving. Infectious diseases (ID) has been less engaged than other specialties in quality measure development, and ID providers must seize the opportunity to engage with quality measure development and research. Antimicrobial stewardship programs are an ideal starting point for ID-related quality measure development; antimicrobial stewardship program interventions and best practices are ID specific, measurable, and effective, yet they are grossly undercompensated. Herein, we provide a scheme for prioritizing research focused on development of ID-specific quality measures. Maturation of quality measurement research in ID, beginning with an initial focus on stewardship-related conditions and then expanding to non-stewardship topics, will allow ID to take control of its future in value-based care and promote the growth of ID through greater recognition of its value.

Monitoring vancomycin blood concentrations reduces mortality risk in critically ill patients: a retrospective cohort study using the MIMIC-IV database

Background

The incidence and mortality of severe Gram-positive cocci infections are particularly high in intensive care units (ICUs). Vancomycin remains the treatment of choice for severe infections caused by Gram-positive cocci, particularly methicillin-resistant Staphylococcus aureus (MRSA). Some guidelines recommend therapeutic drug monitoring (TDM) for critically ill patients treated with vancomycin; however, there is currently a lack of evidence to support that TDM improves the mortality rates of these patients. Therefore, we designed this cohort study to compare the impact of monitoring vancomycin blood concentrations on mortality rates in critically ill patients and to provide evidence to support this routine clinical practice.

Methods

Data were extracted from the Medical Information Mart for Intensive Care (MIMIC)-IV database for a retrospective cohort analysis of critically ill patients receiving intravenous vancomycin treatment. The primary outcome was the 28 day mortality rate. The propensity score matching (PSM) method was used to match the baseline characteristics between patients in the TDM group and the non-TDM group. The relationship between 28 day mortality and vancomycin TDM in the critically ill cohort was evaluated using Cox proportional hazards regression analysis and Kaplan-Meier survival curves. Validation of the primary outcomes was conducted by comparing the PSM model and the Cox proportional hazards regression model. The robustness of the conclusion was subsequently verified by subgroup and sensitivity analyses.

Results

Data for 18,056 critically ill patients who met the study criteria were collected from the MIMIC-IV database. Of these, 7,451 patients had at least one record of vancomycin blood concentration monitoring, which we defined as the TDM group. The TDM group exhibited a 28 day mortality rate of 25.7% (1,912/7,451) compared to 16.2% in the non-TDM group (1,723/10,605). After PSM, 4,264 patients were included in each of the TDM and non-TDM groups, with a 28 day mortality rate of 20.0% (1,022/4,264) in the TDM group and 26.4% (1,126/4,264) in the non-TDM group. Multivariate Cox proportional hazards analysis revealed a significantly lower 28 day mortality risk in the TDM group when compared to the non-TDM group (adjusted hazard ratio [HR]: 0.86; 95% confidence interval [CI]: 0.79, 0.93; p < 0.001). Further PSM analyses (adjusted HR: 0.91; 95% CI: 0.84, 0.99; p = 0.033) confirmed the lower risk of mortality in the TDM group. Kaplan-Meier survival analysis revealed a significantly higher survival rate at 28 days for the TDM group (log-rank test, p < 0.001). Subgroup analysis results indicated that patients with sepsis, septic shock, estimated glomerular filtration rate ≤ 60 mL/min/1.73 m2, undergoing renal replacement therapy, using vasoactive drugs, on mechanical ventilation, and those with higher severity scores (Acute Physiology Score III ≥40, Oxford Acute Severity of Illness Score ≥30, Simplified Acute Physiology Score II ≥ 30) significantly benefited from monitoring vancomycin blood concentrations. The results remained unchanged excluding patients staying in ICU for less than 48 h or those infected with MRSA.

Conclusion

This cohort study showed that monitoring vancomycin blood concentrations is associated with a significantly lower 28 day mortality rate in critically ill patients, highlighting the importance of routinely performing vancomycin TDM in these patients.

Rheumatoid arthritis and risk of osteoarticular infection and death following Staphylococcus aureus bacteraemia: a nationwide cohort study

OBJECTIVES

Osteoarticular infection (OAI) is a feared complication of Staphylococcus aureus bacteraemia (SAB) and is associated with poor outcomes. We aimed to explore the risk of OAI and death following SAB in patients with and without rheumatoid arthritis (RA) and to identify risk factors for OAI in patients with RA.

METHODS

Danish nationwide cohort study of all patients with microbiologically verified first-time SAB between 2006-18. We identified RA, SAB, comorbidities, and RA-related characteristics (e.g. orthopaedic implants and antirheumatic treatment) in national registries including the rheumatology registry DANBIO. We estimated the cumulative incidence of OAI and death and adjusted hazard ratios (HRs, multivariate Cox regression).

RESULTS

We identified 18 274 patients with SAB (n = 367 with RA). The 90-day cumulative incidence of OAI was 23.1% (95% CI 18.8; 27.6) for patients with RA and 12.5% (12.1; 13.0) for patients without RA (non-RA) [HR 1.93 (1.54; 2.41)]. For RA patients with orthopaedic implants cumulative incidence was 29.4% (22.9; 36.2) [HR 1.75 (1.08; 2.85)], and for current users of tumor necrosis factor inhibitors (TNFi) it was 41.9% (27.0; 56.1) [HR 2.27 (1.29; 3.98) compared with non-users]. All-cause 90-day mortality following SAB was similar in RA [35.4% (30.6; 40.3)] and non-RA [33.9% (33.2; 34.5), HR 1.04 (0.87; 1.24)].

CONCLUSION

Following SAB, almost one in four patients with RA contracted OAI corresponding to a doubled risk compared with non-RA. In RA, orthopaedic implants and current TNFi use were associated with approximately doubled OAI risk. One in three died within 90 days in both RA and non-RA. These findings encourage vigilance in RA patients with SAB to avoid treatment delay of OAI.

Effect of HIV Status and Charlson Comorbidity Index on COVID-19 Clinical Outcomes in a Case-Control Study

OBJECTIVES

During the course of the coronavirus disease 2019 (COVID-19) pandemic, numerous comorbidities were identified as risk factors for increased morbidity and mortality. Few studies have examined human immunodeficiency virus (HIV) and COVID-19 co-infection and the impact of HIV on COVID-19 outcomes. In this study, we compared outcomes of people living with HIV with COVID-19 with a control group to examine outcomes.

METHODS

We identified 45 people living with HIV admitted with COVID-19 to one of three large healthcare systems in Memphis, Tennessee, between March 1 and October 31, 2020. We matched the people living with HIV in a 1:1 fashion to a control group of COVID-19-positive patients without a recorded history of HIV and compared clinical outcomes. Nine pairs were not able to be optimally matched, so a sensitivity analysis was completed by repeating the same analyses in the primary analysis while excluding the nine mismatched pairs.

RESULTS

Patients did not differ significantly in demographic variables due to the matching algorithm, and there was no significant difference in measured outcomes between people living with HIV and controls. A CD4 count of <200 cells per microliter was not significantly associated with increased morbidity or mortality. Controlling for HIV status, an elevated Charlson Comorbidity Index score of >3 was associated with increased intubation (P = 0.02), vasopressor use (odds ratio [OR] 4.81, P = 0.04), intensive care unit level of care (OR 4.37, P = 0.007), mortality (OR 7.14, P = 0.02), and length of overall hospital stay in days (P = 0.004).

CONCLUSIONS

We found no difference in outcomes of people living with HIV in comparison to matched controls based on HIV status but found that an increased Charlson Comorbidity Index score led to increased morbidity and mortality regardless of HIV status.

Risk Factors for Persistent Staphylococcus aureus Bacteremia in Children

BACKGROUND

Staphylococcus aureus is a leading cause of pediatric bacteremia. Persistent S. aureus bacteremia (SAB) is associated with increased morbidity and mortality in adults and children. Risk factors for S. aureus bacteremia have been well established, but there is a limited understanding of the factors that contribute to the development of persistent SAB in children.

METHODS

This is a single-center retrospective secondary analysis of a prospective observational study of pediatric patients hospitalized with S. aureus infection over a 3.5-year period at a large, quaternary, children's hospital.

RESULTS

Two hundred fifty-nine children with confirmed S. aureus infection were enrolled in the study. Sixty-five of these were found to have bacteremia, with 28 (43%) developing persistent bacteremia. Patients with persistent SAB were culture-positive for a median of 3.5 days compared with 1 day for those without ( P ≤ 0.001). Children with persistent SAB were more likely to have an identified osteoarticular source of infection (93%, n = 26 vs. 62%, n = 23; P = 0.008) and had a shorter median duration to culture positivity than those without persistent SAB (16 hours vs. 20 hours; P ≤ 0.001). In addition, children with persistent SAB had higher median values of presenting erythrocyte sedimentation rate, peak erythrocyte sedimentation rate, presenting C-reactive protein and peak C-reactive protein. Not surprisingly, hospital length of stay was longer in children with persistent SAB compared with those without.

CONCLUSIONS

These findings suggest that a shorter time to culture positivity, osteoarticular infection, and higher presenting and peak values for select inflammatory markers are potential risk factors for persistent SAB in children.

A review on the development of bacterial multi-epitope recombinant protein vaccines via reverse vaccinology

Bacterial vaccines play a crucial role in combating bacterial infectious diseases. Apart from the prevention of disease, bacterial vaccines also help to reduce the mortality rates in infected populations. Advancements in vaccine development technologies have addressed the constraints of traditional vaccine design, providing novel approaches for the development of next-generation vaccines. Advancements in reverse vaccinology, bioinformatics, and comparative proteomics have opened horizons in vaccine development. Specifically, the use of protein structural data in crafting multi-epitope vaccines (MEVs) to target pathogens has become an important research focus in vaccinology. In this review, we focused on describing the methodologies and tools for epitope vaccine development, along with recent progress in this field. Moreover, this article also discusses the challenges in epitope vaccine development, providing insights for the future development of bacterial multi-epitope genetically engineered vaccines.

Clinical outcome of combination of vancomycin and ceftaroline versus vancomycin monotherapy for treatment of methicillin resistant Staphylococcus aureus bloodstream infection

BACKGROUND

The role of combination therapies for serious methicillin-resistant Staphylococcus aureus (MRSA) infections is widely debated.

METHODS

This retrospective cohort study included adults with MRSA bacteraemia treated between January 1, 2013, to December 31, 2022. Patients receiving combination therapy with vancomycin and ceftaroline were matched in a 2:1 ratio with those on vancomycin monotherapy based on bacteraemia source and illness severity. The primary outcome was frequency of bacteraemia recurrence. Secondary outcomes were all cause 30/90-day mortality, recurrence or mortality at 30/90 days and in hospital length of stay.

RESULTS

Of 57 patients included, 37 (65%) were in the combination group. The overall intensive care unit admission rate was 63.2% (36/57) and the Pitt Bacteraemia Score was 1 [0-4] at the time of diagnosis. The most common source of infection was endovascular/endocarditis (n = 36, 63.2%). Demographic and clinical characteristics were similar between the monotherapy and combination group of patients, except for higher body mass index (32.5 [25.5-36.4] vs. 24.4 [20.9-29], p = 0.004) and a greater immunosuppression prevalence (3 (15%) vs. 0 (0%), p = 0.039) in monotherapy group. There was no significant difference in bacteraemia recurrence (3 (15%) vs. 4 (10.8%), p = 0.7) or all-cause 30-day mortality (3 (15%) vs. 4 (10.8%), p = 0.7) between the two groups.

CONCLUSION

The results of this study are limited by a retrospective observational design; however, combination of vancomycin and ceftaroline for MRSA bacteraemia was not associated with lower bacteraemia recurrence or mortality compared to vancomycin monotherapy.

Determining the Prognostic Value of Complete Blood Count Subgroup Parameters in Staphylococcus aureus Bacteremia

Purpose

Serum cytokine alterations are associated with increased Staphylococcus aureus bacteremia (SAB) mortality. Unfortunately, clinical use of these cytokines is uncommon due to limited availability and high cost. Complete blood count (CBC) with differential reflects the host immune response, and CBC subgroup parameters may have prognostic value in SAB. We sought to determine the association between CBC subgroup parameters on the day of index blood culture and 30-day all-cause mortality in SAB patients.

Methods

We conducted a retrospective study of adult SAB patients with infectious diseases consultation to evaluate the discriminatory capacity of CBC subgroup parameters in predicting SAB mortality. Clinical and microbiological data were collected, including severity of illness and CBC subgroup parameters, on the day of index blood culture. The primary outcome was 30-day all-cause mortality. A multivariable logistic regression model was used to determine the association between patient-level variables and mortality.

Results

A total of 119 patients were included. The overall 30-day all-cause mortality rate was 10.1%. The median neutrophil-to-lymphocyte count ratio (NLCR) among survivors was 13.6 vs 23.2 among non-survivors (p = .007). Median lymphocyte count among survivors was 0.9 x 103 cells/μL vs 0.6 x 103 cells/μL among non-survivors (p = .031). Median platelet count was higher among survivors than non-survivors (239 x 103 cells/μL vs 171 x 103 cells/μL, respectively; p = .018). All other CBC subgroup parameters were similar between the two groups. Known SAB mortality predictors, including age, were also associated with increased mortality. Lower lymphocyte count was independently associated with increased mortality (adjusted odds ratio [aOR] 0.236, 95% confidence interval [CI] 0.064-0.872), as was higher PITT bacteremia score (aOR 2.439, 95% CI 1.565-3.803).

Conclusions

CBC subgroup parameters may have prognostic value in SAB. Additional study is warranted to further ascertain the prognostic value of these readily available laboratory values.

Rifabutin: a repurposed antibiotic with high potential against planktonic and biofilm staphylococcal clinical isolates

Staphylococcus aureus poses a significant threat as an opportunistic pathogen in humans, and animal medicine, particularly in the context of hospital-acquired infections (HAIs). Effective treatment is a significant challenge, contributing substantially to the global health burden. While antibiotic therapy remains the primary approach for staphylococcal infections, its efficacy is often compromised by the emergence of resistant strains and biofilm formation. The anticipated solution is the discovery and development of new antibacterial agents. However, this is a time consuming and expensive process with limited success rates. One potential alternative for addressing this challenge is the repurposing of existing antibiotics. This study investigated the potential of rifabutin (RFB) as a repurposed antibiotic for treating S. aureus infections. The minimum inhibitory concentration (MIC) of rifabutin was assessed by the broth microdilution method, in parallel to vancomycin, against 114 clinical isolates in planktonic form. The minimum biofilm inhibitory concentration (MBIC50) was determined by an adaptation of the broth microdilution method, followed by MTT assay, against a subset of selected 40 clinical isolates organized in biofilms. The study demonstrated that RFB MIC ranged from 0.002 to 6.250 μg/mL with a MIC50 of 0.013 μg/mL. RFB also demonstrated high anti-biofilm activity in the subset of 40 clinical isolates, with confirmed biofilm formation, with no significant MBIC50 differences observed between the MSSA and MRSA strains, in contrast to that observed for the VAN. These results highlight the promising efficacy of RFB against staphylococcal clinical isolates with different resistance patterns, whether in planktonic and biofilm forms.

Risk factors for mortality and complications in peripheral venous catheter-associated Staphylococcus aureus bacteraemia: a large multicentre cohort study

BACKGROUND

Peripheral venous catheter-associated Staphylococcus aureus bacteraemia (PVC-SAB) is a potentially life-threatening nosocomial infection.

AIM

This cohort study aims to identify the risk factors associated with its mortality and complications.

METHODS

Retrospective analysis of a prospective cohort study conducted at two tertiary-care hospitals in Spain. Adult patients admitted between January 2011 and July 2019 which developed PVC-SAB during their hospital stay were included. Primary outcome was all-cause 30- and 90-day mortality. Secondary outcomes were sepsis or septic shock at the onset of bacteraemia, metastatic infection and length of hospital stay. Univariate and multivariate analyses were performed.

FINDINGS

A total of 256 PVC-SAB were diagnosed in 243 patients between 2011 and 2019. Thirty-day and 90-day all-cause mortality were 18.3% and 24.2%, respectively. Lack of susceptible antibiotic administration the day after blood culture collection (odds ratio: 4.14; 95% confidence interval: 1.55-11.03; P = 0.005), sepsis and complicated bacteraemia were identified as independent risk factors for 30- and 90-day mortality; meticillin-resistant S. aureus bacteraemia was identified as an independent risk factor only for 30-day mortality and functional dependence only for 90-day mortality. Persistent bacteraemia and sepsis were associated with septic metastases, which significantly increased hospital stay, and endocarditis. A greater proportion of patients experiencing septic shock were subsequently institutionalized compared to those without.

CONCLUSION

PVC-SAB remains linked to high mortality rates. Prompt administration of appropriate antibiotics is crucial for lowering mortality. A comprehensive diagnostic approach is essential, especially in patients with persistent bacteraemia and implanted cardiovascular devices, to rule out metastatic complications and endocarditis.

Sociodemographic and Clinical Factors Associated With Clinical Outcome in Neuroinfectious Diseases: A Multicenter Retrospective Cohort Study

Objective

To evaluate sociodemographic and clinical factors associated with clinical outcomes in patients hospitalized with neuroinfectious diseases at three tertiary care centers in New York City.

Methods

This retrospective cohort study was conducted at three large urban tertiary care centers between January 1, 2010 and December 31, 2017. Poor clinical outcome was defined as length of hospital stay (LOS) ≥2 weeks and/or discharge to a location other than home. Sociodemographic and clinical factors were obtained from electronic medical records and descriptively analyzed. Multivariate logistic regression analysis investigated relationships between sociodemographic and clinical factors, and outcomes.

Results

Among 205 patients with definitive neuroinfectious diagnoses, older patients were more likely to have a LOS ≥2 weeks (odds ratio [OR]: 1.03; 95% confidence interval [CI]: 1.01-1.05) and less likely to be discharged home (OR: 0.96; 95% CI: 0.94-0.98) than younger patients. Patients with an immunocompromised state were more likely to have a LOS ≥2 weeks (OR: 2.80; 95% CI: 1.17-6.69). Additionally, patients admitted to the intensive care unit (ICU) were more likely to have a LOS ≥2 weeks (OR: 4.65; 95% CI: 2.13-10.16) and less likely to be discharged home (OR: 0.14; 95% CI: 0.06-0.34). There were no statistically significant associations between sex, race, ethnicity, English proficiency, substance use, or poverty index, and clinical outcome.

Conclusions

In this multicenter cohort of hospitalized neuroinfectious diseases, older age, history of immunocompromised state, and admission to the ICU were significantly associated with poor clinical outcome.

Impact of [18F] FDG PET/CT on outcomes in patients with Staphylococcus aureus bacteremia: A retrospective single-center experience

OBJECTIVE

Staphylococcus aureus bacteremia (SAB) is a leading cause of community and hospital-acquired bacteremia with significant morbidity and mortality. Effective management depends on accurate diagnosis, source control and assessment of metastatic infections. [18F] FDG PET/CT has been shown to reduce mortality in high-risk SAB patients. This study aims to evaluate the impact of [18F] FDG PET/CT on outcomes in patients with SAB.

METHODS

Single-center, retrospective, real-life setting study including all consecutive SAB cases from 2017 to 2019. Medical records were analyzed to collect information.

RESULTS

Out of the 315 included patients, 132 underwent [18F] FDG PET/CT. In those patients, a clear focus of infection was more frequently identified, leading to better adapted treatments and extended hospital stays. Overall mortality rates at 30 days, 90 days and one year were 25.1 %, 36.8 % and 44.8 % respectively. Mortality was significantly lower in the [18F] FDG PET/CT group (p < 0.0001) and persisted (p < 0.05) after adjusting for imbalances between groups regarding oncologic patients and deaths within 7 days. The difference in mortality remained significant irrespective of prolonged bacteremia but was not significant with regard to hospital-acquired SAB. Supplementary analysis using the Cox proportional hazards model confirmed that [18F] FDG PET/CT was significantly associated with reduced mortality (p < 0.05).

CONCLUSION

In this real-life cohort, patients with SAB having undergone [18F] FDG PET/CT experienced lower mortality rates, highlighting the additional value of [18F] FDG PET/CT in SAB management. Further research is needed to identify the subpopulations that would benefit most from the integration of [18F] FDG PET/CT in their work-up.

Whole-of-Life Inclusion in Bayesian Adaptive Platform Clinical Trials

Importance

There is a recognized unmet need for clinical trials to provide evidence-informed care for infants, children and adolescents. This Special Communication outlines the capacity of 3 distinct trial design strategies, sequential, parallel, and a unified adult-pediatric bayesian adaptive design, to incorporate children into clinical trials and transform this current state of evidence inequity. A unified adult-pediatric whole-of-life clinical trial is demonstrated through the Staphylococcus aureus Network Adaptive Platform (SNAP) trial.

Observations

Bayesian methods provide a framework for synthesizing data in the form of a probability model that can be used in the design and analysis of a clinical trial. Three trial design strategies are compared: (1) a sequential adult-pediatric bayesian approach that involves a separate, deferred pediatric trial that incorporates existing adult trial data into the analysis model to potentially reduce the pediatric trial sample size; (2) a parallel adult-pediatric bayesian trial whereby separate pediatric enrollment occurs in a parallel trial, running alongside an adult randomized clinical trial; and (3) a unified adult-pediatric bayesian adaptive design that supports the enrollment of both children and adults simultaneously in a whole-of-life bayesian adaptive randomized clinical trial. The SNAP trial whole-of-life design uses a bayesian hierarchical model that allows information sharing (also known as borrowing) between trial age groups by linking intervention effects of children and adults, thereby improving inference in both groups.

Conclusion and Relevance

Bayesian hierarchical models may provide more precision for estimates of safety and efficacy of treatments in trials with heterogenous populations compared to traditional methods of analysis. They facilitate the inclusion of children in clinical trials and a shift from children deemed therapeutic orphans to the vision of no child left behind in clinical trials to ensure evidence for clinical practice exists across the life course. The SNAP trial provides an example of a bayesian adaptive whole-of-life inclusion design that enhances trial population inclusivity and diversity overall, as well as generalizability and translation of findings into clinical practice.

Distinct Clinical Endpoints of Staphylococcus aureus Bacteraemia Complicate Assessment of Outcome

BACKGROUND

We aimed to test the hypothesis that development of metastatic infection represents a distinct clinical endpoint from death due to Staphylococcus aureus bacteremia (SAB).

METHODS

We conducted a retrospective observational study of adults with SAB between 20 December 2019 and 23 August st2022 (n = 464). Simple logistic regression, odds ratios, and z-scores were used to compare host, clinical, and microbiologic features.

RESULTS

Co-occurrence of attributable mortality and metastatic infection was infrequent. Charlson Comorbidity Index and age were strongly associated with attributable mortality, but not metastatic infection. We compared patients with fatal SAB (without clinically-apparent metastatic complications, 14.4% of cohort), metastatic SAB (without attributable mortality, 22.2%), neither complication (56.7%), and overlapping fatal/metastatic SAB (6.7%). Compared to SAB without complications, fatal SAB was specifically associated with older age and multi-morbidity. Metastatic SAB was specifically associated with community acquisition, persistent fever, persistent bacteremia, and recurrence. Endocarditis was over-represented in the fatal/metastatic SAB overlap group, which shared patient characteristics with fatal SAB. In contrast to other (predominantly musculoskeletal) metastatic complications, endocarditis was associated with increased mortality, with death occurring in older multi-morbid patients later after SAB onset.

CONCLUSIONS

Patients with SAB experience distinct clinical endpoints: (i) early death, associated with multi-morbidity and age; (ii) metastatic (predominantly musculoskeletal) SAB; (iii) endocarditis, associated with late death occurring in older people with multi-morbidity, and (iv) bacteraemia without complications. These distinctions could be important for selecting appropriate outcomes in clinical trials: different interventions might be required to reduce mortality versus improve clinical response in patients with metastatic SAB.

Glycan-specific IgM is critical for human immunity to Staphylococcus aureus

Staphylococcus aureus is a major human pathogen, yet the immune factors that protect against infection remain elusive. High titers of opsonic IgG antibodies, achieved in preclinical animal immunization studies, have consistently failed to provide protection in humans. Here, we investigate antibody responses to the conserved S. aureus surface glycan wall teichoic acid (WTA) and detect the presence of WTA-specific IgM and IgG antibodies in the plasma of healthy individuals. Functionally, WTA-specific IgM outperforms IgG in opsonophagocytic killing of S. aureus and protects against disseminated S. aureus bacteremia through passive immunization. In a clinical setting, patients with S. aureus bacteremia have significantly lower WTA-specific IgM but similar IgG levels compared to healthy controls. Importantly, low WTA-IgM levels correlate with disease mortality and impaired bacterial opsonization. Our findings may guide risk stratification of hospitalized patients and inform future design of antibody-based therapies and vaccines against serious S. aureus infection.

Clinical presentation and microbiological characteristics of community-acquired Staphylococcus aureus bacteraemia at a tertiary hospital in Costa Rica

Introduction. Staphylococcus aureus is a leading agent in community-acquired bacteraemia (CAB) and has been linked to elevated mortality rates and methicillin resistance in Costa Rica.Gap statement and aim. To update and enhance previous data obtained in this country, we analysed the clinical manifestations of 54 S. aureus CAB cases in a tertiary hospital and delineated the sequence types (STs), virulome, and resistome of the implicated isolates.Methodology. Clinical information was retrieved from patient files. Antibiotic susceptibility profiles were obtained with disc diffusion and automated phenotypic tests. Genomic data were exploited to type the isolates and for detection of resistance and virulence genes.Results. Primary infections predominantly manifested as bone and joint infections, followed by skin and soft tissue infections. Alarmingly, 70% of patients continued to exhibit positive haemocultures beyond 48 h of treatment modification, with nearly a quarter requiring mechanical ventilation or developing septic shock. The 30-day mortality rate reached an alarming 40%. More than 60% of the patients were found to have received suboptimal or inappropriate antibiotic treatment, and there was an alarming tendency towards the overuse of third-generation cephalosporins as empirical treatment. Laboratory tests indicated elevated creatinine levels, leukocytosis, and bandaemia within the first 24 h of hospitalization. However, most showed improvement after 48 h. The isolates were categorized into 13 STs, with a predominance of representatives from the clonal complexes CC72 (ST72), CC8 (ST8), CC5 (ST5, ST6), and CC1 (ST188). Twenty-four isolates tested positive for mecA, with ST72 strains accounting for 20. In addition, we detected genes conferring acquired resistance to aminoglycosides, MLSB antibiotics, trimethoprim/sulfamethoxazole, and mutations for fluoroquinolone resistance in the isolate collection. Genes associated with biofilm formation, capsule synthesis, and exotoxin production were prevalent, in contrast to the infrequent detection of enterotoxins or exfoliative toxin genes.Conclusions. Our findings broaden our understanding of S. aureus infections in a largely understudied region and can enhance patient management and treatment strategies.

Review: sepsis guidelines and core measure bundles

Sepsis is a major cause of mortality worldwide and is the third-leading cause of death in the United States. Sepsis is resource-intensive and requires prompt recognition and treatment to reduce mortality. The impact of sepsis is not only on in-hospital survival but extends into post-discharge quality of life and risk of re-admission. As the understanding of sepsis physiology evolved, so have the recommended screening tools and treatment protocol which challenge prior standards of care. There have been noteworthy efforts by the Surviving Sepsis Campaign, the Third International Consensus Definitions for Sepsis and the Centers for Medicare and Medicaid Services to establish core measure bundles. This review highlights both the 2021 SSC International Guidelines and the 2015 CMS Severe Sepsis/Septic Shock Core Measure Bundle, or SEP-1. Notably, the SEP-1 bundle was implemented as a value-based purchasing program, linking care of sepsis patients to financial incentives. The objective is to explore the most current evidence-based data to inform clinical practice while utilizing the available guidelines as a roadmap.

Factors Affecting Recurrent Staphylococcus aureus Bacteremia Among Older Patients in Rural Community Hospitals: A Retrospective Cohort Study

Introduction Staphylococcus aureus bacteremia (SAB) poses a significant health risk, particularly among adults over 65 years old, due to age-related vulnerabilities and comorbidities. Recurrent SAB is associated with increased morbidity, prolonged hospitalizations, and higher healthcare costs, necessitating the identification of risk factors that contribute to these recurrent infections. Methods A retrospective cohort study was conducted at a rural community hospital to identify factors associated with recurrent SAB in older patients. Data were extracted from electronic medical records of patients diagnosed with SAB between April 2016 and December 2023. Multivariate logistic regression was employed to analyze the relationship between recurrent SAB and potential risk factors, including age, sex, BMI, dependency on Japanese long-term health insurance, and comorbidities. Results Among 99 patients with SAB, 36 (36.4%) experienced recurrence. Higher BMI was significantly associated with recurrent SAB (OR: 1.15, 95% CI: 1.01-1.31, p = 0.036), while dependency on long-term care was associated with a lower risk of recurrence (OR: 0.20, 95% CI: 0.06-0.64, p = 0.007). Age and sex did not show significant associations with recurrence. Conclusion This study identified higher BMI as a risk factor for recurrent SAB in older patients, while dependency on long-term care was protective. These findings highlight the need for targeted management strategies for patients with higher BMI to prevent recurrent SAB. Further research is needed to explore these associations and confirm their relevance in other clinical settings.

Potential antivirulence and antibiofilm activities of sub-MIC of oxacillin against MDR S. aureus isolates: an in-vitro and in-vivo study

BACKGROUND

Multi-drug resistant Staphylococcus aureus is one of the most common causes of nosocomial and community-acquired infections, with high morbidity and mortality. Treatment of such infections is particularly problematic; hence, it is complicated by antibiotic resistance, and there is currently no reliable vaccine. Furthermore, it is well known that S. aureus produces an exceptionally large number of virulence factors that worsen infection. Consequently, the urgent need for anti-virulent agents that inhibit biofilm formation and virulence factors has gained momentum. Therefore, we focused our attention on an already-approved antibiotic and explored whether changing the dosage would still result in the intended anti-virulence effect.

METHODS

In the present study, we determined the antibiotic resistance patterns and the MICs of oxacillin against 70 MDR S. aureus isolates. We also investigated the effect of sub-MICs of oxacillin (at 1/4 and 1/8 MICs) on biofilm formation using the crystal violet assay, the phenol-sulphuric acid method, and confocal laser scanning microscopy (CLSM). We examined the effect of sub-MICs on virulence factors and bacterial morphology using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and electron microscopy, respectively. Moreover, we studied the effect of sub-MICs of oxacillin (OX) in-vivo using a wound infection model.

RESULTS

Oxacillin at 1/2 MIC showed a significant decrease in bacterial viability, while 1/4 and 1/8 MICs had negligible effects on treated bacterial isolates. Treatment of MDR isolates with 1/4 or 1/8 MICs of oxacillin significantly reduced biofilm formation (64% and 40%, respectively). The treated MDR S. aureus with sub-MICs of OX exhibited a dramatic reduction in several virulence factors, including protease, hemolysin, coagulase, and toxic shock syndrome toxin-1 (TSST-1) production. The sub-MICs of OX significantly decreased (P < 0.05) the gene expression of biofilm and virulence-associated genes such as agrA, icaA, coa, and tst. Furthermore, oxacillin at sub-MICs dramatically accelerated wound healing, according to the recorded scoring of histological parameters.

CONCLUSION

The treatment of MDR S. aureus with sub-MICs of oxacillin can help in combating the bacterial resistance and may be considered a promising approach to attenuating the severity of S. aureus infections due to the unique anti-biofilm and anti-virulence activities.