Reduced Mortality of Staphylococcus aureus Bacteremia in a Retrospective Cohort Study of 2139 Patients: 2007-2015

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.

Clonality, Virulence Genes, and Antimicrobial Resistance of Dairy Ruminants in Mastitic Milk-Associated Staphylococcus aureus in Sicily

Background:Staphylococcus aureus is one of the most prevalent pathogens causing mastitis in dairy animals and represents a serious issue of public health concern due to its resistance against multiple antimicrobials. Objectives: This study assessed 101 S. aureus isolates obtained from quarter milk of animals with subclinical mastitis in the Ragusa area (Sicily, Italy). Methods: Antibiotic resistance against nine antibiotics was evaluated using the Kirby-Bauer method, and the Minimum Inhibitory Concentration (MIC) values were measured for oxacillin (OXA) and vancomycin (VA). Additionally, the isolates were genetically characterized through multiplex PCR to identify the presence of spa, mecA, mecC, pvl, vanA, vanB, and vanC genes, along with pulsed-field gel electrophoresis analysis and multi-locus sequence typing (MLST). Results: The highest rates of antibiotic resistance were found against gentamicin (47.5%) and erythromycin (29.7%), with 86.1% of strains exhibiting resistance to at least two antimicrobials and 33.7% showing resistance to three antimicrobial classes. Furthermore, the results indicated that the presence of antibiotic resistance genes was not correlated with phenotypic resistance, and a phylogenetic analysis revealed varying phenotypic resistance profiles even within the same PFGE cluster. Lastly, alongside a new allelic profile ST 9471, MLST analysis identified five additional STs clustered into three CCs, with CC5 originating from human ancestral strains through human-to-animal host transfers, making it the dominant group. Conclusions: This study provided valuable insights into regional trends, allowing for the identification of significant antibiotic-resistant patterns and offering an understanding of bacterial dynamics in these environments, underscoring the importance of routine resistance surveillance in dairy farms.

Vancomycin Area Under the Curve to Minimum Inhibitory Concentration Ratio for Treatment Effectiveness in Pediatric and Neonatal Staphylococcal Infections: A Systematic Review

OBJECTIVE

To review pediatric data on vancomycin exposure threshold against methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (MR-CoNS).

METHODS

A systematic review was conducted through July 2023. Publications in English that explored vancomycin effectiveness threshold against MRSA, CoNS, or S aureus in pediatrics were eligible. Effectiveness examined included clinical improvement, microbiologic sterilization, recurrence, and mortality, as defined by each individual study.

RESULTS

Twelve studies were eligible. One on MRSA bacteremia (MRSA-B) identified an area under the curve to minimum inhibitory concentration ratio (AUC:MIC) of 300 mg × hr/L associated with rapid bacteremia clearance. Two on CoNS bacteremia (percentage of MR-CoNS unreported) demonstrated an AUC of 300 mg x hr/L regardless of MIC and an AUC:MIC of 280 mg × hr/L for bacteriologic cure, respectively; and one on S aureus bacteremia (25.5% MRSA) found an AUC:MIC of 400 mg × hr/L for clinical improvement.

CONCLUSIONS

There is overall limited pediatric data, and the observed AUC:MIC thresholds should be interpreted as hypothesis generating only. Further, the effectiveness outcome could be refined in future research by using time to bacteremia clearance only, as odds of complications increase with each additional day of MRSA-B, whereas the definition of recurrence is not standardized, and mortality is low. Additionally, extrapolating AUC:MIC for MRSA to CoNS is beyond the stated usage of current guidelines. To achieve an AUC:MIC ratio against CoNS with a MIC of >1 mg/L would require higher AUC with potential nephrotoxicity. More data on AUC (regardless of MIC) for MR-CoNS bacteremia are needed.

Molecular epidemiology and clinical characteristics of Staphylococcus aureus bacteremia in Japanese adults

INTRODUCTION

Staphylococcus aureus bacteremia (SAB), especially when caused by methicillin-resistant S. aureus (MRSA), is of considerable clinical importance. In recent years, the proportion of MRSA among S. aureus has decreased, and a relative increase in the proportion of methicillin-susceptible S. aureus (MSSA) has been observed. It is therefore necessary to consider both MRSA and MSSA when assessing the microbiological and clinical significance of SAB.

MATERIALS AND METHODS

We included SAB cases from the Nara Medical University Hospital between January 2015 and February 2017. We performed drug susceptibility testing, toxicity gene analysis, multilocus sequence typing (MLST), and polymerase chain reaction-based open reading frame typing (POT) of stored strains to integrate clinical and bacteriological characteristics.

RESULTS

There were 90 cases during the experimental period (42 MRSA and 48 MSSA), with 30-day mortality rates of 19 % for MRSA and 10.4 % for MSSA. Deaths were more frequently complicated by septic shock and disseminated intravascular coagulation. MLST studies showed that ST8, ST764, ST1, and ST15 were prevalent in the MRSA group, whereas ST5, ST188, and ST12 were prevalent in MSSA. Infective endocarditis cases had a long time from onset to the initiation of effective antimicrobials and were all MSSA. MLST and POT results correlated well, and POT appeared to have better discriminatory power.

CONCLUSIONS

The severity and mortality of SAB, along with the microbiological characteristics of causative isolates, vary by location and time. Continued studies integrating clinical and microbiological investigations are thus needed.

Impact of adherence to quality indicators and effects of targeted treatment with cefazolin or flucloxacillin on in-hospital mortality in patients with methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infections: a retrospective observational study

PURPOSE

To analyze the associations between adherence to quality indicators (QIs) in the treatment of bloodstream infections caused by methicillin-susceptible Staphylococcus (S.) aureus (MSSA) and in-hospital mortality.

METHODS

A retrospective observational study was conducted in patients admitted between 2019 and 2023 to Hospital St. Georg in Leipzig, Germany, with at least one positive blood culture for S. aureus. Ten QIs were categorized into four groups based on blood culture results, echocardiography, antibiotic treatment, and other parameters such as infectious disease (ID) specialist consultation. Propensity score (PS) matching was used to compare in-hospital mortality between MSSA patients treated with flucloxacillin and those treated with cefazolin. Multivariate Cox regression analysis was performed to determine risk factors associated with in-hospital mortality.

RESULTS

Of the 637 patients with S. aureus bloodstream infections, 495 patients with MSSA infection (77.8%) were included in the study. After the introduction of mandatory ID consultation in 2020, the median QI score increased to 9 out of a maximum of 10 points and was significantly higher in surviving cases than in fatal cases in subsequent years. There was a non-significant decrease in in-hospital mortality from 2019 (28.8%) to 2023 (22.7%) (p = 0.432). Based on PS matching, cefazolin had a favorable hazard ratio of 0.44 (95% CI 0.28-0.71; p < 0.001) for in-hospital mortality. The results of multivariate Cox regression analysis showed a significantly higher survival rate in patients who received QI-based management, including transesophageal echocardiography and antibiotic therapy initiated within 24 h.

CONCLUSIONS

ID consultation is associated with better adherence to quality improvement measures. Targeted MSSA therapy with cefazolin, early initiation of antibiotic therapy, and adherence to antimicrobial treatment protocols increased survival rates in our study setting.

Restriction of arginine induces antibiotic tolerance in Staphylococcus aureus

Staphylococcus aureus is responsible for a substantial number of invasive infections globally each year. These infections are problematic because they are frequently recalcitrant to antibiotic treatment. Antibiotic tolerance, the ability of bacteria to persist despite normally lethal doses of antibiotics, contributes to antibiotic treatment failure in S. aureus infections. To understand how antibiotic tolerance is induced, S. aureus biofilms exposed to multiple anti-staphylococcal antibiotics are examined using both quantitative proteomics and transposon sequencing. These screens indicate that arginine metabolism is involved in antibiotic tolerance within a biofilm and support the hypothesis that depletion of arginine within S. aureus communities can induce antibiotic tolerance. Consistent with this hypothesis, inactivation of argH, the final gene in the arginine synthesis pathway, induces antibiotic tolerance. Arginine restriction induces antibiotic tolerance via inhibition of protein synthesis. In murine skin and bone infection models, an argH mutant has enhanced ability to survive antibiotic treatment with vancomycin, highlighting the relationship between arginine metabolism and antibiotic tolerance during S. aureus infection. Uncovering this link between arginine metabolism and antibiotic tolerance has the potential to open new therapeutic avenues targeting previously recalcitrant S. aureus infections.

Adherence to and clinical utility of "quality indicators" for Staphylococcus aureus bacteremia: a retrospective, multicenter study

BACKGROUND

We aimed to improve the prognosis, treatment, and management of Staphylococcus aureus bacteremia (SAB) by evaluating the association between adherence to quality indicators (QIs) and clinical outcomes in patients with their clinical outcomes.

METHODS

We retrospectively collected clinical and microbiological data on hospitalized patients with SAB from 14 hospitals (three with >  600, two with 401-600, five with 201-400, and four with ≤ 200 beds) in Japan from January to December 2022. The SAB management quality was evaluated using the SAB-QI score (ranging from 0 to 13 points), which consists of 13 QIs (grouped into five categories) based on previous literature.

RESULTS

Of the 4,448 positive blood culture episodes, 289 patients with SAB (6.5%) were enrolled. The SAB-QI scores ranged from 3 to 13, with a median score of 9 points. The SAB-QI score was highest in middle-sized hospitals with 401-600 beds. Adherence to each of the four QI categories (blood culture, echocardiography, source control, and antibiotic treatment) was significantly higher in survived cases than in fatal cases. Kaplan-Meier curves with log-rank tests demonstrated that higher adherence to SAB-QIs indicated a better prognosis. Logistic regression analysis revealed that age, methicillin resistance, multiple comorbidities (≥ 2), and low SAB-QI score were significantly associated with 30-day mortality in patients with SAB.

CONCLUSIONS

Our study highlights that greater adherence to the SAB-QIs correlates with improved patient outcomes. Management of patients with SAB should follow these recommended indicators to maintain the quality of care, especially for patients with poor prognosticators.

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

OBJECTIVES

This study aimed to investigate the clinical impact of the Intelligent Antimicrobial System (iAMS) on patients with bacteraemia due to methicillin-resistant (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA).

METHODS

A total of 1008 patients with suspected SA infection were enrolled before and after the implementation of iAMS. Among them, 252 with bacteraemia caused by SA, including 118 in the iAMS and 134 in the non-iAMS groups, were evaluated.

RESULTS

The iAMS group exhibited a 5.2% (from 55.2% to 50.0%; P = 0.96) increase in the 1-year survival rate. For patients with MRSA and MSSA compared to the non-iAMS group, the 1-year survival rate increased by 17.6% (from 70.9% to 53.3%; P = 0.41) and 7.0% (from 52.3% to 45.3%; P = 0.57), respectively, both surpassing the rate of the non-iAMS group. The iAMS intervention resulted in a higher long-term survival rate (from 70.9% to 52.3%; P = 0.984) for MRSA patients than for MSSA patients. MRSA patients experienced a reduced length of hospital stay (from 23.3% to 35.6%; P = 0.038), and the 45-day discharge rate increased by 20.4% (P = 0.064). Furthermore, the intervention resulted in a significant 97.3% relative decrease in near miss medication incidents reported by pharmacists (P = 0.013).

CONCLUSIONS

Implementation of iAMS platform improved long-term survival rates, discharge rates, hospitalization days, and medical cost (although no significant differences were observed) among patients with MRSA bacteraemia. Additionally, it demonstrated significant benefits in ensuring drug safety.

Female Sex and Mortality in Patients with Staphylococcus aureus Bacteremia: A Systematic Review and Meta-analysis

Importance

Staphylococcus aureus is the leading cause of death due to bacterial bloodstream infection. Female sex has been identified as a risk factor for mortality in S aureus bacteremia (SAB) in some studies, but not in others.

Objective

To determine whether female sex is associated with increased mortality risk in SAB.

Data Sources

MEDLINE, Embase, and Web of Science were searched from inception to April 26, 2023.

Study Selection

Included studies met the following criteria: (1) randomized or observational studies evaluating adults with SAB, (2) included 200 or more patients, (3) reported mortality at or before 90 days following SAB, and (4) reported mortality stratified by sex. Studies on specific subpopulations (eg, dialysis, intensive care units, cancer patients) and studies that included patients with bacteremia by various microorganisms that did not report SAB-specific data were excluded.

Data Extraction and Synthesis

Data extraction and quality assessment were performed by 1 reviewer and verified by a second reviewer. Risk of bias and quality were assessed with the Newcastle-Ottawa Quality Assessment Scale. Mortality data were combined as odds ratios (ORs).

Main Outcome and Measures

Mortality at or before 90-day following SAB, stratified by sex.

Results

From 5339 studies retrieved, 89 were included (132 582 patients; 50 258 female [37.9%], 82 324 male [62.1%]). Unadjusted mortality data were available from 81 studies (109 828 patients) and showed increased mortality in female patients compared with male patients (pooled OR, 1.12; 95% CI, 1.06-1.18). Adjusted mortality data accounting for additional patient characteristics and treatment variables were available from 32 studies (95 469 patients) and revealed a similarly increased mortality risk in female relative to male patients (pooled adjusted OR, 1.18; 95% CI, 1.11-1.27). No evidence of publication bias was encountered.

Conclusions and Relevance

In this systematic review and meta-analysis, female patients with SAB had higher mortality risk than males in both unadjusted and adjusted analyses. Further research is needed to study the potential underlying mechanisms.

A mapping review of methicillin-resistant Staphylococcus aureus proportions, genetic diversity, and antimicrobial resistance patterns in Cameroon

BACKGROUND

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has increased and poses a significant threat to human and animal health in Cameroon and the world at large. MRSA strains have infiltrated various settings, including hospitals, communities, and livestock, contributing to increased morbidity, treatment costs, and mortality. This evidence synthesis aims to understand MRSA prevalence, resistance patterns, and genetic characterization in Cameroon.

METHODS

The methodology was consistent with the PRISMA 2020 guidelines. Studies of any design containing scientific data on MRSA prevalence, genetic diversity, and antimicrobial resistance patterns in Cameroon were eligible for inclusion, with no restrictions on language or publication date. The search involved a comprehensive search strategy in several databases including Medline, Embase, Global Health, Web of Science, African Index Medicus, and African Journal Online. The risk of bias in the included studies was assessed using the Hoy et al tool, and the results were synthesized and presented in narrative synthesis and/or tables and graphs.

RESULTS

The systematic review analyzed 24 studies, mostly conducted after 2010, in various settings in Cameroon. The studies, characterized by moderate to low bias, revealed a wide prevalence of MRSA ranging from 1.9% to 46.8%, with considerable variation based on demographic and environmental factors. Animal (0.2%), food (3.2% to 15.4%), and environmental samples (0.0% to 34.6%) also showed a varied prevalence of MRSA. The genetic diversity of MRSA was heterogeneous, with different virulence gene profiles and clonal lineages identified in various populations and sample types. Antimicrobial resistance rates showed great variability in the different regions of Cameroon, with notable antibiotic resistance recorded for the beta-lactam, fluoroquinolone, glycopeptide, lincosamide, and macrolide families.

CONCLUSION

This study highlights the significant variability in MRSA prevalence, genetic diversity, and antimicrobial resistance patterns in Cameroon, and emphasizes the pressing need for comprehensive antimicrobial stewardship strategies in the country.

Methicillin-Resistant Staphylococcus aureus Bloodstream Infections in Hospitalized Patients in Peru

There is a knowledge gap in the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) causing bloodstream infections (BSIs) in Peru. Through a surveillance study in 13 hospitals of 10 Peruvian regions (2017-2019), we assessed the proportion of MRSA among S. aureus BSIs as well as the molecular typing of the isolates. A total of 166 S. aureus isolates were collected, and 36.1% of them were MRSA. Of note, MRSA isolates with phenotypic and genetic characteristics of the hospital-associated Chilean-Cordobes clone (multidrug-resistant SCCmec I, non-Panton-Valentine leukocidin [PVL] producers) were most commonly found (70%), five isolates with genetic characteristics of community-associated MRSA (CA-MRSA)-SCCmec IV, PVL-producer-(8.3%) were seen in three separate regions. These results demonstrate that hospital-associated MRSA is the most frequent MRSA found in patients with BSIs in Peru. They also show the emergence of S. aureus with genetic characteristics of CA-MRSA. Further studies are needed to evaluate the extension of CA-MRSA dissemination in Peru.

Restriction of Arginine Induces Antibiotic Tolerance in Staphylococcus aureus

Staphylococcus aureus is responsible for a substantial number of invasive infections globally each year. These infections are problematic because they are frequently recalcitrant to antibiotic treatment, particularly when they are caused by Methicillin-Resistant Staphylococcus aureus (MRSA). Antibiotic tolerance, the ability for bacteria to persist despite normally lethal doses of antibiotics, is responsible for most antibiotic treatment failure in MRSA infections. To understand how antibiotic tolerance is induced, S. aureus biofilms exposed to multiple anti-MRSA antibiotics (vancomycin, ceftaroline, delafloxacin, and linezolid) were examined using both quantitative proteomics and transposon sequencing. These screens indicated that arginine metabolism is involved in antibiotic tolerance within a biofilm and led to the hypothesis that depletion of arginine within S. aureus communities can induce antibiotic tolerance. Consistent with this hypothesis, inactivation of argH, the final gene in the arginine synthesis pathway, induces antibiotic tolerance under conditions in which the parental strain is susceptible to antibiotics. Arginine restriction was found to induce antibiotic tolerance via inhibition of protein synthesis. Finally, although S. aureus fitness in a mouse skin infection model is decreased in an argH mutant, its ability to survive in vivo during antibiotic treatment with vancomycin is enhanced, highlighting the relationship between arginine metabolism and antibiotic tolerance during S. aureus infection. Uncovering this link between arginine metabolism and antibiotic tolerance has the potential to open new therapeutic avenues targeting previously recalcitrant S. aureus infections.

Optimal drug therapy for Staphylococcus aureus bacteraemia in adults

PURPOSE OF REVIEW

Staphylococcus aureus is a significant human pathogen, causing a variety of infections, from skin and soft tissue infections to endocarditis, bone and joint infections and deep tissue abscesses. Mortality from S. aureus bacteraemia remains high, without major therapeutic advances in recent decades.

RECENT FINDINGS

In recent years, optimized dosing of antibiotics is increasingly being recognized as a cornerstone of management for severe infections including S. aureus bacteraemia. This comprehensive review details the pharmacokinetics/pharmacodynamics (PK/PD) targets for commonly used antistaphylococcal antibiotics and the doses predicted to achieve them in clinical practice. Recent advances in dosing of teicoplanin and use of cefazolin in CNS infections and findings from combination therapy studies are discussed. Drug exposure relationships related to toxicity are also detailed.

SUMMARY

This review details the different PK/PD targets for drugs used to treat S. aureus bacteraemia and how to apply them in various scenarios. The drug doses that achieve them, and the risks of toxicity are also provided.

The association of female sex with management and mortality in patients with Staphylococcus aureus bacteraemia

OBJECTIVES

The association of biological female sex with outcome in patients with Staphylococcus aureus bacteraemia remains unresolved. The aim of this study was to determine the independent association of female sex with management and mortality in patients with S. aureus bacteraemia.

METHODS

This is a post hoc analysis of prospectively collected data from the S. aureus Bacteraemia Group Prospective Cohort Study. Adult patients with monomicrobial S. aureus bacteraemia at Duke University Medical Center were enrolled from 1994 to 2020. Univariable and multivariable Cox regression analyses were performed to assess differences in management and mortality between females and males.

RESULTS

Among 3384 patients with S. aureus bacteraemia, 1431 (42%) were women. Women were, as compared with men, more often Black (581/1431 [41%] vs. 620/1953 [32%], p < 0.001), haemodialysis dependent (309/1424 [22%] vs. 334/1940 [17%], p 0.001) and more likely to be infected with methicillin-resistant S. aureus (MRSA) (697/1410 [49%] MRSA in women vs. 840/1925 [44%] MRSA in men, p 0.001). Women received shorter durations of antimicrobial treatment (median 24 [interquartile range 14-42] vs. 28 [interquartile range 14-45] days, p 0.005), and were less likely to undergo transesophageal echocardiography as compared with men (495/1430 [35%] vs. 802/1952 [41%], p < 0.001). Despite these differences, female sex was not associated with 90-day mortality in either univariable (388/1431 [27%] in women vs. 491/1953 [25%] in men, p 0.204) or multivariable analysis (adjusted hazard ratio for women 0.98 [95% CI, 0.85-1.13]).

DISCUSSION

Despite significant differences in patient characteristics, disease characteristics, and management, women and men with S. aureus bacteraemia have a similar mortality risk.

Treatment and outcome of gram-positive bacteremia in patients receiving extracorporeal membrane oxygenation

BACKGROUND

While guidance exists for management of blood stream infections with various invasive devices, there are currently limited data to guide antibiotic selection and duration for bacteremia in patients receiving extracorporeal membrane oxygenation (ECMO).

OBJECTIVE

To evaluate the treatment and outcomes of thirty-six patients with Staphylococcus aureus and Enterococcus bacteremia on ECMO support.

METHODS

Blood culture data was retrospectively analyzed from patients with Staphylococcus aureus bacteremia (SAB) or Enterococcus bacteremia who underwent ECMO support between March 2012 and September 2021 at Brooke Army Medical Center.

RESULTS

Of the 282 patients who received ECMO during this study period, there 25 (9%) patients developed Enterococcus bacteremia and 16 (6%) developed SAB. SAB occurred earlier in ECMO as compared to Enterococcus (median day 2 IQR (1-5) vs. 22 (12-51), p = 0.01). The most common duration of antibiotics was 28 days after clearance for SAB and 14 days after clearance for Enterococcus. 2 (5%) patients underwent cannula exchange with primary bacteremia, and 7 (17%) underwent circuit exchange. 1/3 (33%) patients with SAB and 3/10 (30%) patients with Enterococcus bacteremia who remained cannulated after completion of antibiotics had a second episode of SAB or Enterococcus bacteremia.

CONCLUSION

This single center case series is the first to describe the specific treatment and outcomes of patients receiving ECMO complicated by SAB and Enterococcus bacteremia. For patients who remain on ECMO after completion of antibiotics, there is a risk of a second episode of Enterococcus bacteremia or SAB.

Prevalence of Multidrug-Resistant Pathogens Causing Neonatal Early and Late Onset Sepsis, a Retrospective Study from the Tertiary Referral Children's Hospital

Introduction

Sepsis is the most severe infectious disease with the highest mortality rate, particularly among neonates admitted to the neonatal intensive care unit (NICU). This study retrospectively analyzed the epidemiology, antibiotic resistance profiles, and prevalence of multidrug-resistant (MDR) bacteria isolated from blood or cerebrospinal fluid (CSF) cultures in order to evaluate the appropriateness of initial empirical therapy for neonatal sepsis.

Methods

A retrospective study was conducted in the NICU from January 1, 2015, to December 31, 2022. Microbiological data from patients admitted to the NICU were anonymously extracted from the Laboratory of Microbiology database. Neonatal sepsis was classified into two types: early-onset sepsis (EOS), which occurs within the first 72 hours of life, and late-onset sepsis (LOS) for those begins later.

Results

A total of 679 bacterial strains, 543 from blood and 136 from CSF, were detected in 631 neonates. Among these, 378 isolates (55.67%) were Gram-positive bacteria, and 301 isolates (44.33%) were Gram-negative bacteria. The most frequently isolated pathogens were Coagulase-negative staphylococci (CoNS) (36.52%), followed by Klebsiella pneumoniae (20.47%) and Escherichia coli (13.84%). In EOS, 121 strains were found, CoNS represented the majority (33.88%), followed by Klebsiella pneumoniae (23.97%) and Escherichia coli (8.26%). Early-onset septicemia exhibited 67 (55.37%) MDR bacteria. In LOS, 558 strains were isolated, CoNS represented the majority of pathogens (37.10%), followed by Klebsiella pneumoniae (19.71%) and Escherichia coli (15.05%). Late-onset septicemia showed 332 (59.50%) MDR bacteria. High rates of MDR were found in CoNS (76.21%), carbapenem-resistant Klebsiella pneumoniae (66.91%), and MRSA (33.33%).

Conclusion

The study revealed an alarming prevalence of MDR strains isolated from neonatal sepsis, emphasizing the necessity of finding effective prevention and treatment measures. Colistin can be used for MDR Gram-negative bacteria, while vancomycin and teicoplanin can be considered treatment therapies for staphylococcal infections.

Predictors of mortality of Staphylococcus aureus bacteremia among patients hospitalized in a Swiss University Hospital and the role of early source control; a retrospective cohort study

S. aureus bacteremia is associated with high mortality. The aim was to identify predictors of mortality among patients with S. aureus bacteremia and evaluate the role of early source control. This retrospective study was conducted at the Lausanne University Hospital, Switzerland. All episodes of S. aureus bacteremia among adult patients from 2015 to 2021 were included. During the study period, 839 episodes of S. aureus bacteremia were included, of which 7.9% were due to methicillin-resistant isolates. Bacteremias were related to bone or joint infections (268; 31.9%), followed by bacteremia of unknown origin (158; 18.8%), proven endocarditis (118; 14.1%) and lower-respiratory tract infections (79; 9.4%). Overall 28-day mortality was 14.5%. Cox multivariate regression model showed that Charlson comorbidity index > 5 (P < 0.001), nosocomial bacteremia (P 0.019), time to blood culture positivity ≤ 13 h (P 0.004), persistent bacteremia for ≥ 48 h (P 0.004), sepsis (P < 0.001), bacteremia of unknown origin (P 0.036) and lower respiratory tract infection (P < 0.001) were associated with 28-day mortality, while infectious diseases consultation within 48 h from infection onset (P < 0.001) was associated with better survival. Source control was warranted in 575 episodes and performed in 345 episodes (60.0%) within 48 h from infection onset. Results from a second multivariate analysis confirmed that early source control (P < 0.001) was associated with better survival. Mortality among patients with S. aureus bacteremia was high and early source control was a key determinant of outcome. Infectious diseases consultation within 48 h played an important role in reducing mortality.

All-Cause and Infection-Related Mortality in Staphylococcus aureus Bacteremia, a Multicenter Prospective Cohort Study

Background

Staphylococcus aureus bacteremia (SAB) is a heterogeneous disease with changing epidemiology due to changing demographics and evolving clinical management. SAB is associated with high mortality, but the current fraction of infection-related mortality is less well quantified.

Methods

In a multicenter prospective cohort study of consecutive patients with SAB, we determined clinical features of SAB and determined 90-day mortality and risk factors of all-cause and infection-related mortality. Infection-related mortality was based on an adjudication committee evaluation.

Results

Four hundred ninety patients with SAB were included, with community-acquired (n = 166), health care-associated (n = 163), and hospital-acquired SAB (n = 161). Endocarditis (n = 90, 18.3%), peripheral intravenous catheter infection (n = 80, 16.3%), and septic arthritis (n = 58, 11.8%) were the most frequent diagnoses, but proportions differed for community, health care, and hospital acquisition. One hundred ninety-two patients (39%) had permanent implanted prosthetic material (eg, prosthetic joint, heart valve, pacemaker). Day 90 all-cause mortality was 33% (n = 161), with 60% adjudicated as infection-related, and 90% of infection-related deaths occurring in the first 30 days post-SAB. Infection-related deaths after 30 days were rare and mainly related to endocarditis. Determinants associated with day 90 infection-related mortality were age (odds ratio [OR], 1.09; 95% CI, 1.06-1.11), Charlson comorbidity index (OR, 1.13; 95% CI, 1.01-1.26), septic shock (OR, 9.78; 95% CI, 4.56-20.95), endocarditis (OR, 3.4; 95% CI, 1.75-6.61), and persistent SAB at 48 hours (OR, 2.36; 95% CI, 1.27-4.37).

Conclusions

Mortality due to S. aureus infection remains high and mainly occurs in the first 30 days, which could guide end points in future studies.

Investigational agents for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia: progress in clinical trials

INTRODUCTION

Bacteremia caused by Staphylococcus aureus is common. Cases caused by methicillin-resistant S. aureus (MRSA) are particularly formidable and often lethal. The mortality associated with MRSA bacteremia has not significantly decreased over the past couple of decades and concerns regarding efficacy and toxicity of standard therapy highlight the need for novel agents and new therapeutic approaches.

AREAS COVERED

This paper explores clinical trials investigating novel therapeutic approaches to S. aureus bacteremia. There is a special focus on MRSA bacteremia. Monotherapy and combination therapies and novel antimicrobials and adjunctive therapies that are only recently being established for therapeutic use are discussed.

EXPERT OPINION

The unfavorable safety profile of combination antimicrobial therapy in clinical trials has outweighed its benefits. Therefore, future investigation should focus on optimizing duration and de-escalation protocols. Antibody and bacteriophage lysin-based candidates have mostly been limited to safety trials, but progress with these agents is demonstrated through a lysin-based agent receiving a phase III trial. Antibiotics indicated for use in treating MRSA skin infections see continued investigation as treatments for MRSA bacteremia despite the difficulty of completing trials in this patient population. Promising agents include dalbavancin, ceftobiprole, ceftaroline, and exebacase.

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

Introduction

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

Methods

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

Results

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

Discussion

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

In-Vitro Cytotoxicity and Clinical Correlates of MRSA Bacteremia

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections are associated with significant morbidity and mortality. MRSA secretes a number of virulence factors and pore-forming toxins that enable tissue invasion. Prior studies have found associations between decreased toxin production and poor outcomes in invasive MRSA infection, particularly in pneumonia. In this retrospective observational cohort study of MRSA bacteremia in adult patients 2007-2015, we examined whether cytotoxicity was associated with 30-day mortality. Isolates were obtained from 776 patients and screened for cytotoxicity in a human HL-60 cell model, antimicrobial susceptibility and spa type, and clinical data were abstracted from charts. We did not find an association between low cytotoxic activity and 30-day mortality in univariate logistic regression analyses. There was a difference in distribution of the genotypes across cytotoxicity phenotypes, with spa-CC008 accounting for a larger proportion of isolates in the high cytotoxicity group. Isolates with a skin and soft tissue primary infective site had a higher median cytotoxicity. There was no association between cytotoxicity and host factors such as age or comorbidity burden. The isolates in our study came from heterogeneous primary sites of infection and were predominantly from spa-CC002 and spa-CC008 lineages, so it is possible that findings in prior studies reflect a different distribution in genotypes and clinical syndromes. Overall, in this large study of cytotoxicity of MRSA bloodstream isolates, we did not find the low cytotoxicity phenotype to be predictive of poor outcomes in MRSA bacteremia.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Select controversies in the management of methicillin-resistant Staphylococcus aureus bacteremia: answers and remaining questions from recent evidence

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia continues to cause significant morbidity and mortality despite advances in medical therapy. Vancomycin therapy remains the standard of care for most cases of MRSA bacteremia but has pharmacokinetic and pharmacodynamic limitations, dosing complications, and known toxicity. Welcomed clinical trials have recently addressed some of the controversies that plague this field, including optimization of vancomycin dosing and use of combination therapy. In this review, we discuss these trials and their implications for clinical care and future research.

Palliative care consultation in patients with Staphylococcus aureus bacteremia

BACKGROUND

Palliative care consultation has shown benefits across a wide spectrum of diseases, but the utility in patients with Staphylococcus aureus bacteremia remains unclear despite its high mortality.

AIM

To examine the frequency of palliative care consultation and factors associated with palliative care consult in Staphylococcus aureus bacteremia patients in the United States.

DESIGN

A population-based retrospective analysis using the Nationwide Inpatient Sample database in 2014, compiled by the Healthcare Costs and Utilization Project of the Agency for Healthcare Research and Quality.

SETTING/SUBJECTS

All inpatients with a discharge diagnosis of Staphylococcus aureus bacteremia (ICD-9-CM codes; 038.11 and 038.12).

MEASUREMENTS

Palliative care consultation was identified using ICD-9-CM code V66.7. Patients' baseline characteristics and outcomes were compared between those with and without palliative care consult.

RESULTS

A total of 111,320 Staphylococcus aureus bacteremia admissions were identified in 2014. Palliative care consult was observed in 8140 admissions (7.3%). Palliative care consultation was associated with advanced age, white race, comorbidities, higher income, teaching/urban hospitals, Midwest region, Methicillin-resistant Staphylococcus aureus bacteremia and the lack of echocardiogram. Palliative care consult was also associated with shorter but more expensive hospitalizations. Crude mortality was 53% (4314/8140) among admissions with palliative care consult and 8% (8357/10,3180) among those without palliative care consult (p < 0.001).

CONCLUSIONS

Palliative care consultation was infrequent during the management of Staphylococcus aureus bacteremia, and a substantial number of patients died during their hospitalizations without palliative care consult. Given the reported benefit in other medical conditions, palliative care consultation may have a role in Staphylococcus aureus bacteremia. Selecting patients who may benefit the most should be explored.

Infective Endocarditis in Patients on Chronic Hemodialysis

BACKGROUND

Infective endocarditis (IE) is a common and serious complication in patients receiving chronic hemodialysis (HD).

OBJECTIVES

This study sought to investigate whether there are significant differences in complications, cardiac surgery, relapses, and mortality between IE cases in HD and non-HD patients.

METHODS

Prospective cohort study (International Collaboration on Endocarditis databases, encompassing 7,715 IE episodes from 2000 to 2006 and from 2008 to 2012). Descriptive analysis of baseline characteristics, epidemiological and etiological features, complications and outcomes, and their comparison between HD and non-HD patients was performed. Risk factors for major embolic events, cardiac surgery, relapses, and in-hospital and 6-month mortality were investigated in HD-patients using multivariable logistic regression.

RESULTS

A total of 6,691 patients were included and 553 (8.3%) received HD. North America had a higher HD-IE proportion than the other regions. The predominant microorganism was Staphylococcus aureus (47.8%), followed by enterococci (15.4%). Both in-hospital and 6-month mortality were significantly higher in HD versus non-HD-IE patients (30.4% vs. 17% and 39.8% vs. 20.7%, respectively; p < 0.001). Cardiac surgery was less frequently performed among HD patients (30.6% vs. 46.2%; p < 0.001), whereas relapses were higher (9.4% vs. 2.7%; p < 0.001). Risk factors for 6-month mortality included Charlson score (hazard ratio [HR]: 1.26; 95% confidence interval [CI]: 1.11 to 1.44; p = 0.001), CNS emboli and other emboli (HR: 3.11; 95% CI: 1.84 to 5.27; p < 0.001; and HR: 1.73; 95% CI: 1.02 to 2.93; p = 0.04, respectively), persistent bacteremia (HR: 1.79; 95% CI: 1.11 to 2.88; p = 0.02), and acute onset heart failure (HR: 2.37; 95% CI: 1.49 to 3.78; p < 0.001).

CONCLUSIONS

HD-IE is a health care-associated infection chiefly caused by S. aureus, with increasing rates of enterococcal IE. Mortality and relapses are very high and significantly larger than in non-HD-IE patients, whereas cardiac surgery is less frequently performed.

β-Lactams against the Fortress of the Gram-Positive Staphylococcus aureus Bacterium

The biological diversity of the unicellular bacteria-whether assessed by shape, food, metabolism, or ecological niche-surely rivals (if not exceeds) that of the multicellular eukaryotes. The relationship between bacteria whose ecological niche is the eukaryote, and the eukaryote, is often symbiosis or stasis. Some bacteria, however, seek advantage in this relationship. One of the most successful-to the disadvantage of the eukaryote-is the small (less than 1 μm diameter) and nearly spherical Staphylococcus aureus bacterium. For decades, successful clinical control of its infection has been accomplished using β-lactam antibiotics such as the penicillins and the cephalosporins. Over these same decades S. aureus has perfected resistance mechanisms against these antibiotics, which are then countered by new generations of β-lactam structure. This review addresses the current breadth of biochemical and microbiological efforts to preserve the future of the β-lactam antibiotics through a better understanding of how S. aureus protects the enzyme targets of the β-lactams, the penicillin-binding proteins. The penicillin-binding proteins are essential enzyme catalysts for the biosynthesis of the cell wall, and understanding how this cell wall is integrated into the protective cell envelope of the bacterium may identify new antibacterials and new adjuvants that preserve the efficacy of the β-lactams.

Analysis of Multidrug Resistance in Staphylococcus aureus with a Machine Learning-Generated Antibiogram

Multidrug resistance (MDR) surveillance consists of reporting MDR prevalence and MDR phenotypes. Detailed knowledge of the specific associations underlying MDR patterns can allow antimicrobial stewardship programs to accurately identify clinically relevant resistance patterns. We applied machine learning and graphical networks to quantify and visualize associations between resistance traits in a set of 1,091 Staphylococcus aureus isolates collected from one New York hospital between 2008 and 2018. Antimicrobial susceptibility testing was performed using reference broth microdilution. The isolates were analyzed by year, methicillin susceptibility, and infection site. Association mining was used to identify resistance patterns that consisted of two or more individual antimicrobial resistance (AMR) traits and quantify the association among the individual resistance traits in each pattern. The resistance patterns captured the majority of the most common MDR phenotypes and reflected previously identified pairwise relationships between AMR traits in S. aureus Associations between β-lactams and other antimicrobial classes (macrolides, lincosamides, and fluoroquinolones) were common, although the strength of the association among these antimicrobial classes varied by infection site and by methicillin susceptibility. Association mining identified associations between clinically important AMR traits, which could be further investigated for evidence of resistance coselection. For example, in skin and skin structure infections, clindamycin and tetracycline resistance occurred together 1.5 times more often than would be expected if they were independent from one another. Association mining efficiently discovered and quantified associations among resistance traits, allowing these associations to be compared between relevant subsets of isolates to identify and track clinically relevant MDR.

Vancomycin or Daptomycin Plus a β-Lactam Versus Vancomycin or Daptomycin Alone for Methicillin-Resistant Staphylococcus aureus Bloodstream Infections: A Systematic Review and Meta-Analysis

Aims: Several in vitro and in vivo studies demonstrated that adding a β-lactam to vancomycin (VAN) or daptomycin (DAP) can provide synergy against methicillin-resistant Staphylococcus aureus (MRSA). However, the results from clinical studies were controversial. The objective of this systematic review and meta-analysis was to compare the efficacy and safety of using VAN or DAP plus a β-lactam (combination therapy) and using VAN or DAP alone (monotherapy) in MRSA bloodstream infections. Methods: We included randomized controlled trials and observational studies evaluating whether combination therapy can improve clinical and microbiological outcomes and safety compared to monotherapy with VAN or DAP in MRSA-related bacteremia. Results: Literature search identified 3 randomized clinical trials and 10 observational studies involving at least 1,796 patients. There were no significant associations between the combination therapy and risk of mortality within 30 days (risk ratios [RRs], 1.10, 95% confidence interval [CI], 0.82-1.46), in-hospital mortality (RR, 0.59, 95% CI, 0.31-1.13) and mortality within 60-90 days (RR, 0.91, 95% CI, 0.64-1.29). There was also no evidence that there was a difference in length of hospital stay between the combination therapy and monotherapy (mean difference, -0.41 days, 95% CI, -3.41 to 2.59). However, compared with monotherapy, combination therapy seemed to have a shorter duration of bacteremia(mean difference, -1.06 days, 95% CI, -1.53 to -0.60), a lower risk of persistent bacteremia (RR, 0.63, 95% CI, 0.51-0.79) and a lower risk of bacteremia recurrence within 60-90 days (RR, 0.61, 95% CI, 0.40-0.92). There were no statistically significant differences in the total number of adverse events, including acute kidney injury (AKI) (RR, 1.52, 95% CI, 0.84-2.73), thrombocytopenia (RR, 1.13, 95% CI, 0.74-1.73), and diarrhea (RR, 1.36, 95% CI, 0.70-2.65), between patients with combination therapy and monotherapy. In subgroup analysis, when the analysis was limited to the studies comparing using DAP plus ceftaroline with monotherapy, we found that the former had a lower risk of mortality within 30 days. In addition, a subgroup analysis limited to randomized clinical trials showed that the combination therapy was associated with a higher risk of AKI compared with using VAN or DAP alone. Conclusions: Although adding a β-lactam to standard therapy seemed to experience a higher clearance compared with monotherapy in patients with MRSA bacteremia, the combination therapy did not increase survival benefits. Based on the available evidence, the combination therapy was not supported as the routine management of MRSA-related bacteremia, and both its harms and benefits should be taken into account.

Staphylococcus aureus bacteremia and cardiac implantable electronic devices in a county hospital setting: a population-based retrospective cohort study

BACKGROUND

Due to a high incidence of cardiac implantable electronic device-associated infective endocarditis (CIED-IE) in cases of Staphylococcus aureus bacteremia (SAB) and high mortality with conservative management, guidelines advocate device removal in all subjects with SAB. We aimed to investigate the clinical course of SAB in patients with a CIED (SAB+CIED) in a Swedish county hospital setting and relate it to guideline recommendations.

METHODS

All CIED carriers with SAB, excluding clinical pocket infections, in the County of Västmanland during 2010-2017 were reviewed retrospectively.

RESULTS

There were 61 cases of SAB+CIED during the study period, and CIED-IE was diagnosed in 13/61 (21%) cases. In-hospital death occurred in 19/61 (31%) cases, 34/61 (56%) cases were discharged with CIED device retained, and 8/61 (13%) cases were discharged after device removal. Subjects dying during hospitalization were elderly and diseased. No events was seen if the CIED was removed. Among four discharged cases with conservatively managed CIED-IE one relapse occured. Among 30 cases discharged with retained CIED and no evidence of IE, 22/30 (73%) cases had an uneventful follow-up, whereas adverse events secondary to overlooked CIED-IE were likely in 1/30 (3%) cases and could not be definitely excluded in additionally 4/30 (13%) cases.

CONCLUSIONS

During the study period, management became more active and prognosis improved. The heterogeneity within the population of SAB+CIED suggests that a management strategy based on an individual risk/benefit analysis could be an alternative to mandatory device removal.

The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of silver nanoparticles against Staphylococcus aureus

AIM

To determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of silver nanoparticles against Staphylococcus aureus (S. aureus).Methodology: The antimicrobial efficacy of the silver nanoparticles was determined by the standard methods of Clinical and Laboratory Standards Institute (CLSI). Different concentrations of silver nanoparticles were prepared, and MIC was calculated by tube macro-dilution method. The MBC was determined by the lowest concentration that kills 99.9% of the initial bacterial population. The data were analyzed by ANOVA and Tukey's post hoc test using SPSS software.

RESULTS

The MIC and MBC of silver nanoparticles against S. aureus was found to be 0.625 mg/ml.

CONCLUSION

The result obtained from this study shows that silver nanoparticles have potential bactericidal effects against S. aureus at a concentration of 0.625 mg/ml. Silver nanoparticles can be incorporated in the root canal medicaments, sealers and irrigants as it possess potent antimicrobial efficacy against S. aureus.

The Emerging Role of β-Lactams in the Treatment of Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI) are associated with substantial morbidity and mortality. Monotherapy with first-line antimicrobials such as vancomycin (VAN; glycopeptide) and daptomycin (DAP; lipopeptide) are inadequate in some cases due to reduced antibiotic susceptibilities or therapeutic failure. In recent years, β-lactam antibiotics have emerged as a potential option for combination therapy with VAN and DAP that may meet an unmet therapeutic need for MRSA BSI. Ceftaroline (CPT), the only commercially available β-lactam in the United States with intrinsic in vitro activity against MRSA, has been increasingly studied in the setting of VAN and DAP failures. Novel combinations of first-line agents (VAN and DAP) with β-lactams have been the subject of many recent investigations due to in vitro findings such as the "seesaw effect," where β-lactam susceptibility may be improved in the presence of decreased glycopeptide and lipopeptide susceptibility. The combination of CPT and DAP, in particular, has become the focus of many scientific evaluations, due to intrinsic anti-MRSA activities and potent in vitro synergistic activity against various MRSA strains. This article reviews the available literature describing these innovative therapeutic approaches for MRSA BSI, focusing on preclinical and clinical studies, and evaluates the potential benefits and limitations of each strategy.

Antimicrobial Resistance and Molecular Epidemiology of Staphylococcus aureus Causing Bloodstream Infections at Ruijin Hospital in Shanghai from 2013 to 2018

Staphylococcus aureus or methicillin-resistant Staphylococcus aureus (MRSA) is an important issue associated with significant morbidity and mortality and well known as a predominant pathogen causing bloodstream infection (BSIs) globally. To estimate the antibiotic resistance and molecular characteristics of S. aureus causing BSIs in Shanghai, 120 S. aureus isolates (20 isolates each year) from the patients with S. aureus BSIs from 2013 to 2018 were randomly selected and enrolled in this study. Fifty-three (44.2%) MRSA isolates were determined, and no isolate was found resistant to vancomycin, daptomycin, synercid, linezolid and ceftaroline. The toxin genes tst, sec, seg and sei were found more frequently among MRSA isolates compared with MSSA isolates (all P < 0.0001). Twenty-nine sequence types (STs) were identified, and ST5 (23.3%) was the most common ST, followed by ST398 (11.7%) and ST764 (10.0%). SCCmec II (73.6%) was the most frequent SCCmec type among MRSA isolates. The dominant clonal complexes (CCs) were CC5 (ST5, ST764, ST965 and ST3066; 36.7%) and the livestock-associated clone CC398 (ST398, 11.7%). MRSA-CC5 was the predominant CC among MRSA isolates (37/53, 69.8%), and CC5-II MRSA was found in 34 isolates accounting for 91.9% (34/37) among CC5 MRSA isolates. In addition, all 29 tst-positive MRSA isolates were CC5-MRSA as well. Our study provided the properties and genotypes of S. aureus causing BSIs at Ruijin Hospital in Shanghai from 2013 to 2018, and might suggest of value clues for the further study insights into pathogenic mechanisms intrinsically referring to the development of human-adapted S. aureus clones and their diffusions.

Mortality of Sepsis in Patients With Rheumatoid Arthritis: A Single-Center Retrospective Analysis and Comparison With a Control Group

INTRODUCTION/BACKGROUND

Patients with rheumatoid arthritis (RA) have a high risk of infections that may require intensive care unit (ICU) admission in case of resulting sepsis. Data regarding the mortality of these patients are very limited. This study investigated clinical characteristics and outcomes of patients with RA admitted to the ICU for sepsis and compared the results to a control cohort without RA.

METHODS

All patients with RA as well as sex-, age-, and admission year-matched controls admitted to the ICU of a university hospital for sepsis between 2006 and 2019 were retrospectively analyzed. Mortality was calculated for both the groups, and multivariate logistic regression was used to determine independent risk factors for sepsis mortality. The positive predictive value of common ICU scores was also investigated.

RESULTS

The study included 49 patients with RA (mean age 67.2 ± 9.0 years, 63.3% females) and 51 matched controls (mean age 67.4 ± 9.5 years, 64.7% females). Among the patients with RA, 42.9% (n = 21) were treated with conventional synthetic (cs) disease-modifying antirheumatic drugs (DMARDs) and 30.6% (n = 15) received glucocorticoids only. Seven (14.3%) patients received biologic (b) DMARDs. The hospital mortality was higher among patients with RA (42.9% vs 15.7%, P = .0016). Rheumatoid arthritis was independently associated with mortality in multivariate logistic regression (P = .001). In patients with RA, renal replacement therapy (P = .024), renal failure (P = .027), and diabetes mellitus (P = .028) were independently associated with mortality. Acute Physiology and Chronic Health Evaluation II (APACHE II), Simplified Acute Physiology Score II (SAPS II), and Sequential Organ Failure Assessment (SOFA) scores were good predictors of sepsis mortality in patients with RA (APACHE II area under the curve [AUC]: 0.78, P = .001; SAPS II AUC: 0.78, P < .001; SOFA AUC 0.78, P < .001), but their predictive power was higher among controls.

CONCLUSIONS

Hospital sepsis mortality was higher in patients with RA than in controls. Rheumatoid arthritis itself is independently associated with an increased sepsis mortality. Renal replacement therapy, renal failure, and diabetes were associated with an increased mortality. Common ICU scores were less well predictors of sepsis mortality in patients with RA compared to non-RA controls.

Molecular Epidemiology of Staphylococcus aureus Lineages in Wild Animals in Europe: A Review

Staphylococcus aureus is an opportunist pathogen that is responsible for numerous types of infections. S. aureus is known for its ability to easily acquire antibiotic resistance determinants. Methicillin-resistant S. aureus (MRSA) is a leading cause of infections both in humans and animals and is usually associated with a multidrug-resistant profile. MRSA dissemination is increasing due to its capability of establishing new reservoirs and has been found in humans, animals and the environment. Despite the fact that the information on the incidence of MRSA in the environment and, in particular, in wild animals, is scarce, some studies have reported the presence of these strains among wildlife with no direct contact with antibiotics. This shows a possible transmission between species and, consequently, a public health concern. The aim of this review is to better understand the distribution, prevalence and molecular lineages of MRSA in European free-living animals.

Ceftobiprole versus daptomycin in Staphylococcus aureus bacteremia: a novel protocol for a double-blind, Phase III trial

Although Staphylococcus aureus is a common cause of bacteremia, treatment options are limited. The need for new therapies is particularly urgent for methicillin-resistant S. aureus bacteremia (SAB). Ceftobiprole is an advanced-generation, broad-spectrum cephalosporin with activity against both methicillin-susceptible and -resistant S. aureus. This is a Phase III, randomized, double-blind, active-controlled, parallel-group, multicenter, two-part study to establish the efficacy and safety of ceftobiprole compared with daptomycin in the treatment of SAB, including infective endocarditis. Anticipated enrollment is 390 hospitalized adult patients, aged ≥18 years, with confirmed or suspected complicated SAB. The primary end point is overall success rate. Target completion of the study is in the second half of 2021.

Clinicaltrials.gov identifier: NCT03138733