Epidemiology of Methicillin-Resistant Staphylococcus aureus Bacteremia in Children

Pediatric Clinical Outcomes of Nasal Methicillin-resistant Staphylococcus aureus Polymerase Chain Reaction Utilization

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a clinical challenge in selecting empiric antimicrobials for pediatric infections. We implemented nasal MRSA polymerase chain reaction (nMRSA PCR) screening as a diagnostic tool and evaluated its impact on empiric antibiotic use and clinical outcomes.

METHODS

A retrospective single-center study of patients hospitalized with infections who were empirically prescribed anti-MRSA antibiotics was conducted prior to and following the initiation of nMRSA PCR screening. Electronic medical records, pharmacy data and bacterial cultures results were reviewed. Predictive values of nMRSA PCR testing were calculated and the duration of anti-MRSA empiric therapy and clinical outcomes preimplementation and postimplementation were compared.

RESULTS

During the preimplementation period, there were 382 distinct episodes (294 unique patients) that met the inclusion criteria and during post-nMRSA PCR implementation, 394 episodes (360 unique patients) were identified. The median time to discontinuation of anti-MRSA antibiotics and proportion of patients prescribed anti-MRSA antibiotics at discharge were significantly lower in postimplementation compared with preimplementation period; 48 versus 56 hours, P < 0.001 and 20.1% versus 40.3%, P < 0.001, respectively. The negative and positive predictive values of nMRSA PCR compared to clinical culture results were 95.6% and 51.2%, respectively. Predefined adverse outcomes were documented in 11 patients who had early anti-MRSA discontinuation with negative nMRSA PCR results but only 3 were restarted on anti-MRSA treatment and none grew MRSA in clinical cultures.

CONCLUSIONS

Shortened anti-MRSA antibiotic duration, high negative predictive value and low adverse events provide promising evidence that nMRSA PCR is an effective, rapid antimicrobial stewardship tool for hospitalized children.

Association of Antibiotic Route and Outcomes in Children with Methicillin-Resistant Staphylococcus aureus Bacteremic Osteomyelitis

INTRODUCTION

There remains uncertainty about whether transitioning to oral antibiotic therapy is appropriate for the management of children with methicillin-resistant Staphylococcus aureus (MRSA) bacteremic osteomyelitis. We compared clinical outcomes for children with MRSA osteomyelitis with associated bacteremia who were transitioned to discharge oral antibiotic therapy to those discharged on outpatient parenteral antibiotic therapy (OPAT).

METHODS

We performed a retrospective, multicenter, cohort study of children ≤ 18 years hospitalized with MRSA bacteremic osteomyelitis across four children's hospitals from 2007 to 2018 discharged on oral antibiotic therapy versus OPAT. The primary outcome was treatment failure within 6 months of discharge, defined as any of the following: diagnosis of chronic osteomyelitis, conversion from oral to IV antibiotic route, an operative procedure after the index hospitalization (abscess drainage, bone biopsy, arthrocentesis, or pathologic fracture) and/or recrudescence of MRSA bacteremia. Outcomes were analyzed in an inverse propensity score weighted (IPW) cohort.

RESULTS

A total of 106 cases of MRSA bacteremic osteomyelitis were included; 44 (42%) were discharged in the oral antibiotic therapy group and 62 (59%) patients were discharged in the OPAT group. In the IPW cohort, treatment failure within 6 months of discharge occurred in 3.4% of children in the discharge oral therapy group and 16.3% in the OPAT group (P = 0.03). The odds of 6-month composite treatment failure between discharge oral therapy and OPAT were 0.18 (95% CI 0.05-0.61).

CONCLUSIONS

Discharge oral therapy was not associated with higher rates of treatment failure compared to OPAT for children with MRSA bacteremic osteomyelitis.

The Utilization of Echocardiography in Children With Staphylococcus aureus Bacteremia

The need for echocardiography in pediatric Staphylococcus aureus bacteremia (SAB) remains uncertain. We reviewed 331 pediatric SAB cases. Nine subjects, all with comorbidities, met the echocardiogram criteria for infective endocarditis (IE). IE was associated with congenital heart disease and prolonged bacteremia, suggesting that echocardiography is unnecessary in most children with SAB.

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.

Cefazolin and Carbapenem Combination to Treat Persistent Methicillin-sensitive Staphylococcus aureus Bacteremia in Preterm Infants

Encouraged by bacteremia clearance using antistaphylococcal beta-lactams plus carbapenem combination in adults with refractory methicillin-sensitive Staphylococcus aureus infection, we present our experience with 2 preterm infants and review 1 previously published case. Noted successful bacteremia clearance in all 3 must be weighed against possible adverse effects associated with carbapenem use.

Predictive Value of Methicillin-Resistant Staphylococcus aureus Nasal Swab PCR Assay for MRSA Infection in Critically Ill Pediatric Patients

BACKGROUND

Critically ill pediatric patients are frequently initiated methicillin-resistant Staphylococcus aureus (MRSA) active antibiotics during infection evaluation even though MRSA infections are rare in many patient populations. The MRSA nasal swab polymerase chain reaction assay (MRSA-NS-PCR) is a test that has been shown to have a high negative predictive value (NPV) for MRSA infection in adults. This study evaluated the diagnostic test characteristics of the MRSA-NS-PCR in predicting the presence of MRSA infection in critically ill pediatric patients.

STUDY DESIGN

A retrospective cohort study was performed in a 44-bed pediatric intensive care unit (PICU) between 2013 and 2017. 3860 pediatric patients (54% male, median age 4 years [IQR 1-11 years]) admitted to the PICU who met pediatric systemic inflammatory response syndrome (pSIRS) criteria, were screened with a MRSA-NS-PCR, and had cultures obtained within seven days of MRSA-NS-PCR collection were included. Predictive values and post-test probabilities of the MRSA-NS-PCR for MRSA infection were calculated.

RESULTS

MRSA-NS-PCR was positive in 8.6% of patients. MRSA infection was identified in 40 patients, equaling an incidence rate of 2 per 1000 patient days. The MRSA-NS-PCR demonstrated a positive predictive value (PPV) of 9.7%, a NPV of 99.8%, and a post-test probability for a negative test of 0.2% for MRSA infection.

CONCLUSIONS

The MRSA-NS-PCR has a poor PPV but a high NPV for MRSA infection in PICU patients when the incidence of MRSA infection is low. Creation of protocols to guide antimicrobial selection based on MRSA-NS-PCR results may lead to improved antimicrobial stewardship and significant risk reduction.

Pediatric Utilization of Methicillin-resistant Staphylococcus aureus Nasal Swabs for Antimicrobial Stewardship

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) can cause serious infections and empiric treatment regimens in children frequently include an anti-MRSA antibiotic. Studies in adults have demonstrated a high negative predictive value (NPV) of MRSA nasal swabs (MNS) in a variety of infectious syndromes. Negative MNS have been utilized as a tool to guide de-escalation of anti-MRSA antibiotics in adults, especially in those with lower respiratory tract infections, but data in children is minimal. The primary objective of this study was to determine the NPV and positive predictive value (PPV) of MNS in children hospitalized for treatment of an infection.

METHODS

This was a single-site, retrospective cohort study of pediatric patients admitted with a suspected infectious diagnosis who had an MNS performed during their hospitalization between June 1, 2018 and November 25, 2022.

RESULTS

This study identified 172 patients who met the inclusion criteria. Eleven (6.4%) nasal swabs were positive for MRSA and 10 (5.8%) microbiological cultures from suspected sources of infection were identified to be positive for MRSA. The MNS was found to have a sensitivity of 20%, specificity of 94%, PPV of 18% and NPV of 95% for all sites of infection.

CONCLUSION

MNS has a high NPV and low PPV in children. MNS can be utilized as an antimicrobial stewardship tool to guide the safe de-escalation of anti-MRSA antibiotics in children.

Staphylococcus aureus Bacteremia in the Pediatric Emergency Department and Predictors of Poor Outcome

BACKGROUND

Staphylococcus aureus has become the leading cause of bacteremia among previously healthy children older than 5 years.

METHODS

We aimed to describe the infants presenting to pediatric emergency departments and diagnosed with S. aureus bacteremia (SAB) and identify predictors (clinical and laboratory variables) of poor outcome (complications, sequelae or death). We performed an observational study and subanalysis of a multicenter prospective registry, including every patient under the age of 18 years with a positive blood culture obtained at any of the 22 participating Spanish pediatric emergency departments between 2011 and 2016. We considered chronic diseases, immunosuppressive treatment and the presence of mechanical devices as risk factors for SAB.

RESULTS

Of the 229 patients with SAB, 176 (76.9%) were previously healthy, 192 (83.8%) had a normal pediatric assessment triangle and 158 (69.0%) had an associated focal infection (mainly osteoarticular infection, skin and soft tissue infection and pneumonia). Fifty-three patients (23.1%) had 1 or more risk factors for SAB. Thirty-one (13.5%) presented a poor outcome, including 4 deaths (1.7%). A poor outcome was more common in patients with SAB risk factors [odds ratio (OR): 7.0; 95% CI: 3.2-15.4], abnormal PAT (OR: 5.9; 95% CI: 2.6-13.3), elevated procalcitonin (OR: 1.2; 95% CI: 1.05-1.3) and C-reactive protein, the latter being the only independent predictor of poor outcome (OR: 1.01; 95% CI: 1.01-1.02).

CONCLUSIONS

Overall, children with SAB are previously healthy, appear well, and have an associated focal infection. One of 7 had a poor outcome, with C-reactive protein being the only predictor identified.

Staphylococcus aureus Bacteremia in Pediatric Patients: Uncovering a Rural Health Challenge

Background

Staphylococcus aureus bacteremia poses significant risk for morbidity and mortality. This may be exacerbated in rural populations facing unique health challenges.

Methods

To investigate factors influencing S. aureus bacteremia outcomes, we conducted a retrospective cohort study of children admitted to St. Louis Children's Hospital (SLCH) from 2011 to 2019. Exposures included rurality (defined by the Rural-Urban Continuum Code), Area Deprivation Index, and outside hospital (OSH) admission before SLCH admission. The primary outcome was treatment failure, a composite of 90-day all-cause mortality and hospital readmission.

Results

Of 251 patients, 69 (27%) were from rural areas; 28 (11%) were initially admitted to an OSH. Treatment failure occurred in 39 (16%) patients. Patients from rural areas were more likely to be infected with methicillin-resistant S. aureus (45%) vs urban children (29%; P = .02). Children initially admitted to an OSH, vs those presenting directly to SLCH, were more likely to require intensive care unit-level (ICU) care (57% vs 29%; P = .002), have an endovascular source of infection (32% vs 12%; P = .004), have a longer duration of illness before hospital presentation (4.1 vs 3.0 days; P = .04), and have delayed initiation of targeted antibiotic therapy (3.9 vs 2.6 days; P = .01). Multivariable analysis revealed rural residence (adjusted odds ratio [aOR], 2.3; 95% CI, 1.1-5.0), comorbidities (aOR, 2.9; 95% CI, 1.3-6.2), and ICU admission (aOR, 3.9; 95% CI, 1.9-8.3) as predictors of treatment failure.

Conclusions

Children from rural areas face barriers to specialized health care. These challenges may contribute to severe illness and worse outcomes among children with S. aureus bacteremia.

Predictive Factors to Guide Empiric Antimicrobial Therapy of Acute Hematogenous Osteomyelitis in Children

BACKGROUND

Acute hematogenous osteomyelitis (AHO) is a serious infection in children. Pediatric Infectious Diseases Society guidelines recommend empiric methicillin-resistant Staphylococcus aureus (MRSA) therapy in regions where MRSA accounts for more than 10-20% of all staphylococcal osteomyelitis. We sought to examine factors present at the time of admission which may predict etiology and guide empiric treatment for pediatric AHO in a region with endemic MRSA.

METHODS

We reviewed admissions with International Classification of Diseases 9/10 codes for AHO from 2011 to 2020 in otherwise healthy children. Medical records were reviewed for clinical and laboratory parameters present on the day of admission. Logistic regression was used to determine clinical variables independently associated with (1) MRSA infection and (2) non-Staphylococcus aureus infection.

RESULTS

A total of 545 cases were included. An organism was identified in 77.1% of cases and S. aureus was the most common (66.2%); 18.9% of all AHO cases were MRSA. Organisms besides S. aureus were identified in 10.8% of cases. CRP >7 mg/dL, subperiosteal abscess, history of any prior skin or soft tissue infection (SSTI) and need for intensive care unit admission were independently associated with MRSA infection. Vancomycin was used as an empiric treatment in 57.6% of cases. If the above criteria were relied upon to predict MRSA AHO, empiric vancomycin use could have been reduced by 25%.

CONCLUSIONS

Critical illness, CRP >7 mg/dL at the time of presentation, subperiosteal abscess and history of SSTI are suggestive of MRSA AHO, and could be considered when planning empiric therapy. Further work is needed to validate these findings before wider implementation.

The impact of infectious diseases consultation for children with Staphylococcus aureus bacteremia

BACKGROUND

Despite clear benefit of improved outcomes in adults, the impact of infectious diseases (ID) consultation for Staphylococcus aureus bacteremia in children remains understudied.

METHODS

To assess the impact of pediatric ID consultation on management and outcomes, we conducted a cohort study of children with S. aureus bacteremia at St. Louis Children's Hospital from 2011 to 2018. We assessed adherence to six established quality-of-care indicators (QCIs). We applied propensity score methodology to examine the impact of ID consultation on risk of treatment failure, a composite of all-cause mortality or hospital readmission within 90 days.

RESULTS

Of 306 patients with S. aureus bacteremia, 193 (63%) received ID consultation. ID consultation was associated with increased adherence to all QCIs, including proof-of-cure blood cultures, indicated laboratory studies, echocardiography, source control, targeted antibiotic therapy, and antibiotic duration. Obtaining proof-of-cure blood cultures and all indicated laboratory studies were associated with improved outcomes. In propensity score-weighted analyses, risk of treatment failure was similar among patients who did and did not receive ID consultation. However, the number of events was small and risk estimates were imprecise.

CONCLUSIONS

For children with S. aureus bacteremia, ID consultation improved adherence to QCIs, some of which were associated with improved clinical outcomes.

IMPACT

In children with Staphylococcus aureus bacteremia, consultation by an infectious diseases (ID) physician improved adherence to established quality-of-care indicators (QCIs). The current literature regarding ID consultation in pediatric S. aureus bacteremia is sparse. Three prior international studies demonstrated improved quality of care with ID consultation, though results were disparate regarding clinical outcomes. This article impacts the current literature by strengthening the evidence that ID consultation in children improves adherence to QCIs, and demonstrates that adherence to QCIs improves clinical outcomes.

Genomic Basis of Occurrence of Cryptic Resistance among Oxacillin- and Cefoxitin-Susceptible mecA-Positive Staphylococcus aureus

The oxacillin- and cefoxitin-susceptible mecA-positive Staphylococcus aureus is a novel "stealth" methicillin-resistant S. aureus (MRSA) type. Here, we sequenced the whole genome of two oxacillin- and cefoxitin-susceptible mecA-positive MRSA isolates from breast abscesses in a lactating woman and a nasal swab of a healthy student in Guangzhou for investigating the mechanism underlying its occurrence. The reversion of these isolates was selected by exposure to sub-MICs of cefoxitin with or without mupirocin. The mecA expression of both parental strains and their revertants was determined, and the whole genome of the revertants was sequenced. Comparative whole-genome analyses performed for both strains revealed that mecA of the clinical strain was mutated by a single-bp insertion at the 262nd position in the tandem repeat region of the gene, and this mutation that led to the formation of a premature stop codon. The colonizing strain was mutated by a novel G-to-A base substitution in the second promoter region (-35 bp) of mecA. The mecA expression level of strain 697 revertant was 37 times higher than that of the parental strain. Although the mecA expression level was even higher for parental strain 199 compared with that for its revertant, its cDNA sequence contained a single-bp insertion. Collectively, both the missense and single substitution mutations of the second promoter of mecA could render MRSA isolates as "stealth" MRSA, thereby emphasizing the importance of combining phenotype tests with mecA or penicillin-binding protein 2a detection for the identification of MRSA. IMPORTANCE The oxacillin- and cefoxitin-susceptible mecA-positive Staphylococcus aureus is a novel type of "stealth" methicillin-resistant S. aureus (MRSA), which is difficult to be detected using conventional methods. To investigate the genomic basis of their occurrence, we sequenced the whole genome of two previously recovered oxacillin- and cefoxitin-susceptible mecA-positive MRSA isolates from breast abscesses in a lactating woman and a nasal swab of a healthy student in Guangzhou. Complete SCCmec structure was absent except for mecA in clinical isolate 199. Additionally, a novel single-base pair insertion was observed in the clinical strain, which resulted in premature termination and a frameshift mutation. The colonizing isolate 697 had a Scc-mec-type IVa, and the second promoter region (-35 bp) of mecA was mutated by a novel G-to-A base substitution. The reversion of oxacillin- and cefoxitin-susceptible mecA-positive S. aureus to resistant MRSA isolates was selected by exposure to subminimum inhibitory cefoxitin with or without mupirocin.

Early-onset neonatal sepsis and antibiotic use in Indonesia: a descriptive, cross-sectional study

BACKGROUND

Early diagnosis and prompt antibiotic treatment are crucial to reducing morbidity and mortality of early-onset sepsis (EOS) in neonates. However, this strategy remains challenging due to non-specific clinical findings and limited facilities. Inappropriate antibiotics use is associated with ineffective therapy and adverse outcomes. This study aims to determine the characteristics of EOS and use of antibiotics in the neonatal-intensive care units (NICUs) in Indonesia, informing efforts to drive improvements in the prevention, diagnosis, and treatment of EOS.

METHODS

A descriptive study was conducted based on pre-intervention data of the South East Asia-Using Research for Change in Hospital-acquired Infection in Neonates project. Our study population consisted of neonates admitted within 72 h of life to the three participating NICUs. Neonates who presented with three or more clinical signs or laboratory results consistent with sepsis and who received antibiotics for 5 consecutive days were considered to have EOS. Culture-proven EOS was defined as positive blood or cerebrospinal fluid culture. Type and duration of antibiotics used were also documented.

RESULTS

Of 2,509 neonates, 242 cases were suspected of having EOS (9.6%) with culture-proven sepsis in 83 cases (5.0% of neonatal admissions in hospitals with culture facilities). The causative organisms were mostly gram-negative bacteria (85/94; 90.4%). Ampicillin / amoxicillin and amikacin were the most frequently prescribed antibiotics in hospitals with culture facilities, while a third-generation cephalosporin was mostly administered in hospital without culture facilities. The median durations of antibiotic therapy were 19 and 9 days in culture-proven and culture-negative EOS groups, respectively.

CONCLUSIONS

The overall incidence of EOS and culture-proven EOS was high in Indonesia, with diverse and prolonged use of antibiotics. Prospective antibiotic surveillance and stewardship interventions are required.

Increasing Pediatric Infectious Diseases Consultation Rates for Staphylococcus aureus Bacteremia

Introduction

Staphylococcus aureus bacteremia (SAB) in children is associated with significant mortality and morbidity, including recurrent bacteremia. Infectious disease consultation (IDC) improves SAB outcomes in adult patients. However, increasing IDC and impact for pediatric patients with SAB is not well described.

Methods

This quality improvement project aimed to increase IDC for SAB events at a quaternary pediatric medical center. First, we evaluated the local practices regarding pediatric SAB and engaged stakeholders (July 2018-August 2020). We added an advisory comment supporting IDC for SAB to all blood culture results in September 2020. Using statistical process control charts, we monitored the number of SAB events with IDC before a SAB event without IDC. Finally, we evaluated SAB recurrences before and after initiating the advisory comment.

Results

In the baseline period, 30 of 49 (61%) SAB events received an IDC with a mean of 1.4 SAB events with IDC before a SAB event without IDC. Postintervention, 22 of 23 (96%) SAB events received IDC with a mean of 14 events with IDC before 1 event without IDC. The SAB recurrence rate was 8%, with 6 events in 4 children; none of the index cases resulting in recurrence received an IDC (P = 0.0002), and all occurred before any intervention.

Conclusions

An electronic advisory comment supporting IDC for SAB significantly increased the rate of pediatric IDC with no further SAB recurrence episodes following intervention. This low-resource intervention may be considered in other pediatric centers to optimize SAB management.

Management and Prevention of Staphylococcus aureus Infections in Children

Staphylococcus aureus is a common skin commensal with the potential to cause severe infections resulting in significant morbidity and mortality. Up to 30% of individuals are colonized with S aureus, though infection typically does not occur without skin barrier disruption. Infection management includes promptly addressing the source of infection, including sites of metastatic infection, and initiation of effective antibiotics, which should be selected based on local antibiotic susceptibility patterns. Given that S aureus colonization is a risk factor for infection, preventive strategies are aimed at optimizing hygiene measures and decolonization regimens for outpatients and critically ill children with prolonged hospitalizations.

Intravenous versus Oral Step-Down for the Treatment of Staphylococcus aureus Bacteremia in a Pediatric Population

Limited data are available regarding optimal antimicrobial therapy for Staphylococcus aureus bacteremia (SAB) in pediatric patients. The purpose of this study was to assess clinical characteristics and outcomes associated with intravenous (IV) versus oral step-down treatment of pediatric SAB. This study evaluated patients aged 3 months to 18 years that received at least 72 h of inpatient treatment for SAB. The primary endpoint was 30-day readmission. Secondary endpoints included hospital length of stay and inpatient mortality. One hundred and one patients were included in this study. The median age was 7.9 years. Patients who underwent oral step-down were less likely to be immunocompromised and more likely to have community-acquired SAB from osteomyelitis or skin and soft tissue infection (SSTI). More patients in the IV therapy group had a 30-day readmission (10 (25.6%) vs. 3 (5.3%), p = 0.006). Mortality was low (5 (5%)) and not statistically different between groups. Length of stay was greater in patients receiving IV therapy only (11 vs. 7 days, p = 0.001). In this study, over half of the patients received oral step-down therapy and 30-day readmission was low for this group. Oral therapy appears to be safe and effective for patients with SAB from osteomyelitis or SSTIs.

Differences Between Methicillin-susceptible Versus Methicillin-resistant Staphylococcus aureus Infections in Pediatrics: Multicenter Cohort Study Conducted in Bogotá, Colombia, 2014-2018

BACKGROUND

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) has changed in recent years. The present article is intended to establish differences between clinical, laboratory and imaging findings and outcomes of MSSA and MRSA infections, as well as among subgroups of infection such as skin and soft tissue infection, osteoarticular, bacteremia or pneumonia in a pediatric population from Bogota, Colombia.

METHODS

Retrospective cohort study using clinical records of patients under 18 years of age treated at the participating centers in Bogota, Colombia, between 2014 and 2018. The first positive S. aureus culture was studied. MSSA and MRSA were compared. The χ2 test, Fisher exact test, and Kruskal-Wallis test were calculated, and the statistical significance was presented using the difference and its 95% CI.

RESULTS

Five hundred fifty-one patients were included; 211 (38%) corresponded to MRSA and 340 (62%) to MSSA for a total of 703 cultures. A significantly higher probability of having an MSSA infection than MRSA was found in patients with previous heart disease (3.3% vs. 0.5%), neurologic disease (5.9% vs. 2.5%), recent major surgeries (11% vs. 5%) or who has an implanted device (11% vs. 4%). In contrast, in severe MRSA infections (bacteremia, osteoarticular infections and pneumonia), a higher rate of complications was seen (admission to the pediatric intensive care unit, mechanical ventilation and vasoactive support), and in osteoarticular MRSA, more than 1 surgery per case was seen (89% vs. 61%). Laboratory results and mortality were similar.

CONCLUSIONS

MRSA was associated with a more severe course in bacteremia, osteoarticular infections and pneumonia. Some classical risk factors associated with MRSA infections were found to be related to MSSA. In general, with the exception of skin and soft tissue infection, there was an increased risk of pediatric intensive care unit admission and mechanical and inotropic support with MRSA in a pediatric population.

Readmission after hospitalization with Staphylococcus aureus bacteremia in children

BACKGROUND

Readmission rate is an important quality measure and can inform patient care. However, readmission of S. aureus bacteremia in children requires further research.

METHODS

We performed a population-based longitudinal observational study using the State Inpatient Database from New York, Florida, and Washington, 2009-2015. Children aged 18 years or younger hospitalized with S. aureus bacteremia were included. The outcome of non-elective readmission was assessed by developing Cox proportional hazards regression models.

RESULTS

Of 1240 children with S. aureus bacteremia, 223 (18.0%) and 351 (28.3%) had non-elective readmission within 30 days and 90 days after discharge, respectively. On multivariable analysis, catheter related infection (hazard ratio, HR: 1.79, 95% confidence interval, CI: 1.31-2.45) was associated with 30-day readmission. The median cost of the original hospitalization for S. aureus bacteremia was $29 914 (interquartile range, IQR: $13 276-$71 284), and that of 30 day readmission was $10 956 (IQR: $5765-$24 753).

CONCLUSIONS

S. aureus bacteremia is associated with a high rate of readmission in children, particularly in those with catheter related infection. Hospitalization with S. aureus bacteremia and readmission are costly. Future research should seek interventions to improve outcomes of S. aureus bacteremia in children, and the results of this study can serve as a benchmark.

PEP27-2, a Potent Antimicrobial Cell-Penetrating Peptide, Reduces Skin Abscess Formation during Staphylococcus aureus Infections in Mouse When Used in Combination with Antibiotics

PEP27, a 27-amino acid (aa) peptide secreted by Streptococcus pneumoniae, is an autolytic peptide that functions as a major virulence factor. To develop a clinically applicable antimicrobial peptide (AMP), we designed PEP27 analogs with Trp substitutions to enhance its antimicrobial activity compared to that of PEP27. Particularly, PEP27-2 showed strong antimicrobial activity against a wide variety of bacteria, including multidrug-resistant (MDR) bacteria. It was found that the antimicrobial activity of PEP27-2 was increased by substituting Trp for the aa at the middle position of PEP27. We found that PEP27-2 acts as an effective cell-penetrating peptide in bacterial and mammalian cells. Here, we proved that subcutaneous infection with MDR Staphylococcus aureus induced skin lesions such as skeletal muscle damage, deep inflammation, and necrosis of the overlaying dermis in mice. Combination treatment with antibiotics revealed synergistic effects, remarkably reducing abscess size and improving the bacteria removal rate from the infection site. Moreover, PEP27-2-antibiotic combination treatment reduced inflammation, lowering levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, inducible NO synthase (iNOS), and cyclooxygenase (COX-2) in skin abscess tissue. The results suggest that the PEP27-2 peptide is a promising therapeutic option for combating MDR bacterial strains by enhancing antibiotic penetration and protecting against MDR bacteria.

Impact of Infectious Diseases Consultation on Management and Outcome of Staphylococcus aureus Bacteremia in Children

BACKGROUND

To examine the impact of infectious diseases consultation (IDC) on the management and outcome of Staphylococcus aureus bacteremia (SAB) in children.

METHODS

A retrospective cohort study of children with SAB at a teritary pediatric hospital (January 2009-June 2015) identified by medical record review as to whether they received an IDC for SAB at the discretion of the admitting physician or surgeon was conducted. Differences in management and outcomes for those with and without IDC were evaluated, and multivariate regression analysis was used to determine factors associated with cure.

RESULTS

There were 100 patients included in the analysis. Fifty-five patients received IDC and 45 had no IDC (NIDC). Appropriate directed therapy within 24 hours (54/55 = 98.2% vs 34/45 = 75.6%, P < .01), choice (54/55 = 98.2% vs 37/45 = 82.2%, P < .01), dose (54/55 = 98.2% vs 36/45 = 80%, P < .01), and duration (52/55 = 94.5% vs 24/45 = 53.3%, P < .01) of directed antibiotic therapy were appropriate in more IDC group patients. Achievement of source control in indicated cases was also more common in the IDC group (28/32 = 87.5% vs 5/26 = 19.1%, P < .01). Appropriate investigation with repeat blood cultures and echocardiograms was not significantly different. All 55 patients in the IDC group had a complete response (cure) compared with 40 of the 45 (88.9%) patients in the NIDC group: 2 patients died and 3 patients had a relapse of infection with subsequent cure. In multivariate regression analysis, methicillin-susceptible SAB and IDC were factors independently associated with cure.

CONCLUSIONS

Children who received IDC for SAB in a tertiary pediatric setting were more likely to have appropriate investigations and management and had improved outcomes.

Reduced Vancomycin Susceptibility, MRSA and Treatment Failure in Pediatric Staphylococcus aureus Bloodstream Infections

BACKGROUND

Clinical implications of reduced vancomycin susceptibility (RVS) among pediatric Staphylococcus aureus bloodstream infections are unknown.

METHODS

We identified all children at 2 children's hospitals with ≥1 blood culture positive for S. aureus. We compared patient and clinical factors for RVS and non-RVS infections using Wilcoxon rank-sum and chi-squared tests. Treatment failure and the duration of bacteremia for RVS versus non-RVS and for methicillin-resistant Staphylococcus aureus (MRSA) versus methicillin-susceptible Staphylococcus aureus (MSSA) infections were compared using multivariable logistic and Poisson regressions, respectively. For MRSA infections, the association of empiric vancomycin monotherapy with treatment failure was assessed using multivariable logistic regression.

RESULTS

RVS was present in 72% (309/426) of cases. No patient or infection characteristics, including methicillin resistance, were associated with RVS. RVS was associated with an increased duration of bacteremia compared with non-RVS infections, aIRR = 1.15 (95% confidence interval: 1.02-1.30). The odds of treatment failure was similar for RVS and non-RVS infections, aOR = 1.04 (0.62-1.74). In contrast, MRSA infections were more likely to have treatment failure than MSSA infections, aOR = 3.03 (95% confidence interval: 1.84-5.00). For MRSA infections, empiric vancomycin monotherapy was associated with an increased odds of treatment failure compared with non-vancomycin or combination anti-MRSA antibiotics, aOR = 3.23 (1.12-9.26).

CONCLUSIONS

RVS was common and was associated with a longer duration of bacteremia but not with treatment failure. Treatment failure was more common for MRSA than for MSSA bloodstream infections. Empiric vancomycin monotherapy increased the odds of treatment failure for MRSA infections.

Impact of a Best Practice Advisory for Pediatric Patients With Staphylococcus aureus Bacteremia

BACKGROUND

Infectious diseases (ID) consultation and optimal antibiotic therapy improve outcomes in Staphylococcus aureus bacteremia (SAB). Data on strategies to improve adherence to these practices in children are limited.

METHODS

This was a quasi-experimental study evaluating the impact of an electronic medical record (EMR)-based best practice advisory (BPA) for SAB, recommending ID consult and optimal antibiotic therapy based on rapid mecA gene detection. Inpatients < 21 years old with SAB before (January 2015-July 2017) and after (August 2017-December 2018) BPA implementation were included. Primary outcome was receipt of ID consult. Secondary outcomes included receipt of optimal therapy, time to ID consult and optimal therapy, recurrent SAB, and 30-day all-cause mortality. ID consultation rates pre- and postimplementation were compared using interrupted time series (ITS) analysis. Hazard ratios (HRs) and 95% confidence intervals (CIs) for time to optimal therapy were calculated using Cox regression.

RESULTS

We included 99 SAB episodes (70 preintervention, 29 postintervention). Preintervention, 48 (68.6%) patients received an ID consult compared to 27 (93.1%) postintervention, but this was not statistically significant on ITS analysis due to a preexisting trend of increasing consultation. Median hours to optimal therapy decreased from 26.1 to 5.5 (P = .03), most notably in patients with methicillin-sensitive S. aureus (MSSA) (42.2 to 10.8; P < .01). On Cox regression, BPA implementation was associated with faster time to optimal therapy (HR, 3.22 [95% CI, 1.04-10.01]).

CONCLUSIONS

Implementation of an EMR-based BPA for SAB resulted in faster time to optimal antibiotic therapy, particularly for patients with MSSA. ID consultation increased throughout the study period and was not significantly impacted by the BPA.

AUCs and 123s: a critical appraisal of vancomycin therapeutic drug monitoring in paediatrics

The revised vancomycin guidelines recommend implementing AUC24-based therapeutic drug monitoring (TDM) using Bayesian methods in both adults and paediatrics. The motivation for this change was accumulating evidence showing aggressive dosing to achieve high troughs, as recommended in the first guidelines for adults and extrapolated to paediatrics, is associated with increased nephrotoxicity without improving clinical outcomes. AUC24-based TDM requires substantial resources that may need to be diverted from other valuable interventions. It can therefore be justified only after certain assumptions are shown to be true: (i) there is a clear relationship between vancomycin efficacy and/or toxicity and the proposed therapeutic range; and (ii) maintaining exposure within the target range with AUC24-based TDM improves clinical outcomes and/or decreases toxicity. In this review, we critically appraise the scientific basis for these assumptions. We find studies evaluating the relationship between vancomycin AUC24/MIC and efficacy in adults and children do not offer strong support for the recommended lower limit of the proposed therapeutic range (i.e. AUC24/MIC ≥400). Nephrotoxicity in children increases in a stepwise manner along the vancomycin exposure continuum but it is unclear if one parameter (AUC24 versus trough) is a superior predictor. Overall, evidence in children suggests good-to-excellent correlation between AUC24 and trough. Most importantly, there is no convincing evidence that the method of vancomycin TDM has a causal role in improving efficacy or reducing toxicity. These findings question the need to transition to resource-intensive AUC24-based TDM over retaining trough-based TDM with lower targets to minimize nephrotoxicity in paediatrics.

Antimicrobial prescribing for treatment of serious infections caused by Staphylococcus aureus and methicillin-resistant Staphylococcus aureus in pediatrics: an expert review

Introduction: Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), remains a significant pathogen in children. Despite evidence of decreasing prevalence, MRSA bacteremia has been closely associated with complications, including certain infections (i.e. musculoskeletal and endovascular) linked to increased treatment failures.Areas covered: This expert review summarized recent published literature on the role of treatment, dosing and administration of antibiotics used to combat serious S. aureus infections in children. The pertinent antibiotics presented were vancomycin, oxazolidinones, semi-synthetic glycopeptides, daptomycin, tigecycline, novel cephalosporins, fosfomycin and lefamulin. Vancomycin has been the most commonly used antibiotic in empiric therapy for serious MRSA infection, with new key recommendations emphasizing a different approach to dosing and therapeutic monitoring. For other antibiotics, data remain limited or clinical trials are underway.Expert opinion: MRSA remains a significant pathogen in the pediatric population. As numerous therapeutic agents are available, many agents have limited data on usage in pediatric patients. Future studies require pharmacokinetic, safety and efficacy studies in pediatric patients to ensure appropriate therapeutic treatment and outcomes. Phage therapy has been used to treat deep-seated MRSA infections and is an emerging investigational treatment option.

Follow-up Blood Cultures in Children With Staphylococcus aureus Bacteremia

BACKGROUND

Staphylococcus aureus is a common pathogen seen in pediatric bloodstream infections. Currently, no evidence-based recommendations are used to guide decisions on the number of follow-up blood cultures (FUBCs) needed to demonstrate infection clearance. Unnecessary cultures increase the risk of false-positives, add to health care costs, and create additional trauma to children and their families. In this study, we examined risk factors for persistent S aureus bacteremia (SAB) and intermittent positive blood cultures (positive cultures obtained after a documented negative FUBC result) to determine the number of FUBCs needed to demonstrate infection clearance in children.

METHODS

Patients ≤18 years who were hospitalized with SAB at Texas Children's Hospital in 2018 were reviewed. We assessed the impact of an infectious disease diagnosis (central line-associated bloodstream infection, osteomyelitis, soft tissue infection, endocarditis, etc) and medical comorbidities on bacteremia duration. Patients with intermittent positive blood cultures were studied to determine the characteristics of this group and overall frequency of reversion to positive cultures.

RESULTS

A total of 122 subjects met the inclusion criteria. The median duration of bacteremia was 1 day (interquartile range: 1-2 days). Only 19 patients (16%) had bacteremia lasting ≥3 days, all of whom had a diagnosis of central line-associated bloodstream infection, osteomyelitis, or endocarditis. Intermittent positive cultures occurred in 5% of patients, with positive cultures after 2 negative FUBC results seen in <1% of patients. Intermittent positive cultures were strongly associated with osteomyelitis and endocarditis.

CONCLUSIONS

On the basis of our sample of children with SAB, additional blood cultures to document sterility are not necessary after 2 FUBC results are negative in well-appearing patients.

Strategies to Prevent Healthcare-Associated Infections: A Narrative Overview

Healthcare-associated infections (HCAIs) are a major source of morbidity and mortality and are the second most prevalent cause of death. Furthermore, it has been reported that for every one-hundred patients admitted to hospital, seven patients in high-income economies and ten in emerging and low-income economies acquire at least one type of HCAI. Currently, almost all pathogenic microorganisms have developed antimicrobial resistance, and few new antimicrobials are being developed and brought to market. The literature search for this narrative review was performed by searching bibliographic databases (including Google Scholar and PubMed) using the search terms: "Strategies," "Prevention," and "Healthcare-Associated Infections," followed by snowballing references cited by critical articles. We found that although hand hygiene is a centuries-old concept, it is still the primary strategy used around the world to prevent HCAIs. It forms one of a bundle of approaches used to clean and maintain a safe hospital environment and to stop the transmission of contagious and infectious microorganisms, including multidrug-resistant microbes. Finally, antibiotic stewardship also has a crucial role in reducing the impact of HCAIs through conserving currently available antimicrobials.

Quantification and interpretation of attributable mortality in core clinical infectious disease journals

Attributable mortality is an important metric that mirrors the public health effect of a potentially harmful infection by accounting not only for the effect of infection on mortality, but also for its prevalence within the target population. We did a systematic literature review to identify how attributable deaths were quantified and interpreted in core clinical infectious diseases journals between Jan 1, 2013, and April 6, 2020. Of the 1591 abstracts screened, 234 entered the primary analysis. Our summary of the epidemiological measures used in these articles reveals fundamental shortcomings in the conception of attributable mortality. Because of its importance as a basis for decision making on public health matters, it is essential to correctly quantify and report on attributable mortality. Our recommendation for quantification and reporting of attributable deaths aids clinical researchers in the correct statistical assessment of the burden of infections. Fictional as well as real data is used to illustrate these issues.

Vancomycin Therapeutic Drug Monitoring in Children: New Recommendations, Similar Challenges

The American Society of Health-System Pharmacists, the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the Society of Infectious Diseases Pharmacists have recently published revised guidelines for the therapeutic monitoring of vancomycin. Previous iterations of the guideline largely focused on targeting vancomycin trough concentrations (VTCs) in the range of 15 to 20 mg/L for therapeutic efficacy. The revised guidelines shift the focus of therapeutic monitoring directly to AUC/MIC-based therapeutic monitoring for children, with a suggestion of a goal AUC/MIC 400 to 800. The primary hesitation in applying these recommendations to children stems from the absence of pediatric clinical data demonstrating correlations with clinical outcomes and either VTC or AUC and no benefit in other secondary outcomes (e.g., recurrence, duration of bacteremia). One can glean indirectly from this that such aggressive dosing and monitoring strategies are unnecessary to achieve therapeutic success in the majority of children with serious methicillin-resistant Staphylococcus aureus infections. Providers should carefully weigh the potential unknown benefits of targeting vancomycin AUC 400 to 800 mg*hr/L in children with the known risks of acute kidney injury associated with increasing the dose of vancomycin as well as the substantial time, effort, and costs of this process.

Effect of Vancomycin Loading Doses on the Attainment of Target Trough Concentrations in Hospitalized Children

OBJECTIVE

Subtherapeutic vancomycin trough concentrations are common in children and may be associated with suboptimal therapeutic response. Our objective was to determine if vancomycin loading doses safely increase the frequency of target trough attainment in hospitalized children.

METHODS

Patients (≥6 months and <18-years-old) who received a vancomycin loading dose between February 1, 2018, and January 30, 2019, were retrospectively enrolled. These patients were compared to a convenience cohort of patients hospitalized between January 1, 2015, and December 31, 2015, who received vancomycin without a loading dose. Target trough concentrations were defined as >15 mg/dL for invasive infections and >10 mg/dL for non-invasive infections.

RESULTS

A total of 151 patients were enrolled, with 77 in the control arm and 74 in the loading dose arm. There was no significant difference in the frequency of comorbidities or need for intensive care unit admission between the two arms. Those receiving a vancomycin loading dose were older (mean age 9.1 vs 5.2 years, p < 0.0001). Patients given a loading dose achieved higher mean initial trough values (13.0 mg/dL vs 9.2 mg/dL, p < 0.0001), were more likely to have an initial trough at or above target (37.0% vs 10.4%, p = 0.0001), were more likely to reach target trough values at any point during therapy (52.1% vs 32.9%, p = 0.0081), and attained a target trough concentration more quickly (mean 41.1 hours vs 58.8 hours, p = 0.0118). There were no significant differences in the frequency of serum creatinine elevation or oliguria at the end of therapy.

CONCLUSIONS

Vancomycin loading doses may improve the ability to safely obtain target trough values in hospitalized children.

Evolution of Multi-Resistance to Vancomycin, Daptomycin, and Linezolid in Methicillin-Resistant Staphylococcus aureus Causing Persistent Bacteremia

The genomic evolution in vivo in persistent infection was critical information for understanding how methicillin-resistant Staphylococcus aureus (MRSA) was adapted to host environments with high antibiotic selective pressure. Thirty-two successive MRSA blood isolates with incremental non-susceptibility to vancomycin (VISA), daptomycin (DRSA), and/or linezolid (LRSA) were isolated from a patient failing multiple courses of antimicrobial therapy during 1,356 days of bacteremia. Whole genome sequencing (WGS) for all consecutive isolates were conducted to characterize the evolutionary pathways, resistance-associated mutations and their temporal relationship with antimicrobial treatment. The WGS-based phylogeny categorized the isogenic strains into three major clades, I (22 isolates), II (7 isolates), and III (3 isolates), respectively, harboring a median (range) of 7 (1–30), 62 (53–65), and 118 (100–130) non-synonymous mutations when compared to the very first isolate. Clade I strains were further grouped into early and late subclades, which, respectively, shared the most recent common ancestor with Clade III strains at day 393.7 and Clade II strain at day 662.5. Clade I and Clade III strains were characterized, respectively, with high rates of VISA (9/22, 40.9%) and VISA-and-DRSA phenotype (2/3, 66.7%). Linezolid-resistance including VISA-DRSA-and-LRSA phenotype was exclusively identified in Clade II strains after eight courses of linezolid treatment. The LRSA displayed a small colony variant phenotype and were associated with G2576T mutations in domain V region of 23S rRNA. Substantial loss of mobile elements or alleles mediating resistance or virulence were identified during the evolution of multi-resistance. However, the gene loss might not be correlated to the development of VISA, DRSA, or LRSA phenotype. In conclusion, MRSA in persistent bacteremia was adapted to harsh host environment through multiple pathways involving both resistance-associated mutations and extensive gene loss.

Early Bayesian Dose Adjustment of Vancomycin Continuous Infusion in Children: a Randomized Controlled Trial

Methicillin-resistant staphylococcal infections are a global burden. Area under the serum concentration-time curve to minimum inhibitory concentration (AUC/MIC) ratio is the pharmacokinetic (PK) parameter that best predicts vancomycin efficacy. Its therapeutic range is narrow, difficult to achieve because of a wide intersubject variability, especially in children, and is not routinely targeted since the AUC is rarely available. We investigated if an early Bayesian dose adjustment would increase the rate of vancomycin target attainment, in the first 24 hours of treatment (H24), in children.We conducted a single-centre randomized controlled trial in 4 pediatric departments of Necker-Enfants Malades hospital (Paris, France). Patients aged 3 months to 17 years for whom intravenous vancomycin was started were eligible and randomized in a 1:1 ratio: routine care were compared with an early vancomycin therapeutic drug monitoring (3h after treatment initiation) followed by an early Bayesian dose adjustment using a previously published population-based PK model that included age, bodyweight and serum creatinine as covariates. The primary outcome was the proportion of patients of each group achieving vancomycin therapeutic range at H24, defined by AUC_0-24/MIC≥400 and AUC_0-24 ≤800mg-h/L.Ninety-nine patients were enrolled: 49 were randomized to the Bayesian group and 50 to the control group. Modified intention-to-treat analysis included 82 patients: 85% of Bayesian group patients achieved H24 vancomycin target versus 57% of control group patients (p=0.007) with no difference regarding iatrogenic events. Early Bayesian dose adjustment increased the proportion of children achieving vancomycin target at H24, which may improve clinical outcomes of methicillin-resistant staphylococcal infections.

Accelerating Initiation of Adequate Antimicrobial Therapy Using Real-Time Decision Support and Microarray Testing

Introduction:

Bloodstream infections (BSI) represent a common cause of sepsis and mortality in children. Early and adequate empirical antimicrobial therapy is a critical component of successful treatment of BSI. Rapid PCR-based diagnostic technologies, such as nucleic acid microarrays, can decrease the time needed to identify pathogens and antimicrobial resistance and have the potential to ensure patients are started on adequate antibiotics as early as possible. However, without appropriate processes to support timely and targeted interpretation of these results, these advantages may not be realized in practice.

Methods:

Our Antimicrobial Stewardship Program (ASP) implemented a quality improvement initiative using the Institute for Healthcare Improvement’s Model for Improvement to decrease the time between a nucleic acid microarray result for Gram-positive bacteremia and the time a patient was placed on adequate antimicrobial therapy. The primary effective intervention was a near real-time notification system to the managing physicians of inadequate antimicrobial therapy via a call from the ASP team.

Results:

Following the intervention, the average time to adequate antimicrobial therapy in patients with Gram-positive BSI and inadequate coverage decreased from 38 hours with the nucleic acid microarray result alone to 4.7 hours when results were combined with an ASP clinical decision support intervention, an 87% reduction.

Conclusions:

The positive effects of rapid-detection technologies to improve patient care are enhanced when combined with clinical decision support tools that can target inadequate antimicrobial treatments in near real time.

Prior antibiotic use and acquisition of multidrug-resistant organisms in hospitalized children: A systematic review

Objective:

Multidrug-resistant organisms (MDROs) cause ~5%–10% of infections in hospitalized children, leading to an increased risk of death, prolonged hospitalization, and additional costs. Antibiotic exposure is considered a driving factor of MDRO acquisition; however, consensus regarding the impact of antibiotic factors, especially in children, is lacking. We conducted a systematic review to examine the relationship between antibiotic use and subsequent healthcare-associated infection or colonization with an MDRO in children.

Design:

Systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline.

Methods:

We searched PubMed and Embase for all English, peer-reviewed original research studies published before September 2018. Included studies evaluated hospitalized children, antibiotic use as an exposure, and bacterial MDRO as an outcome.

Results:

Of the 535 studies initially identified, 29 met the inclusion criteria. Overall, a positive association was identified in most studies evaluating a specific antibiotic exposure (17 of 21, 81%), duration of antibiotics (9 of 12, 75%), and number of antibiotics received (2 of 3, 67%). Those studies that evaluated any antibiotic exposure had mixed results (5 of 10, 50%). Study sites, populations, and definitions of antibiotic use and MDROs varied widely.

Conclusions:

Published studies evaluating this relationship are limited and are of mixed quality. Limitations include observation bias in recall of antibiotic exposure, variations in case definitions, and lack of evaluation of antibiotic dosing and appropriateness. Additional studies exploring the impact of antibiotic use and MDRO acquisition may be needed to develop effective antibiotic stewardship programs for hospitalized children.

Vancomycin Treatment Failure in Children With Methicillin-Resistant Staphylococcus aureus Bacteremia

OBJECTIVES

Limited data exist regarding clinical outcomes of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in children treated with vancomycin. Treatment success in adults correlates best with an area under the curve/minimum inhibitory concentration (AUC₂₄/MIC) ratio ≥400. It is unknown if this relationship is useful in children.

METHODS

Charts of children who received vancomycin ≥5 days for MRSA bacteremia with a steady state trough were reviewed. AUC₂₄/MIC ratios were estimated using 2 different vancomycin clearance equations. Vancomycin treatment failure was defined as persistent bacteremia ≥7 days, recurrent bacteremia within 30 days, or 30-day mortality.

RESULTS

There were 67 bacteremia episodes in 65 patients. Nine (13.4%) met failure criteria: persistent bacteremia (n = 6), recurrent bacteremia (n = 2), 30-day mortality (n = 1). There were no differences between patients receiving <60 mg/kg/day and ≥60 mg/kg/day of vancomycin in median trough (11.9 versus 12.3 mg/L, p = 0.1). Troughs did not correlate well with AUC₂₄/MIC ratios (R ² = 0.32 and 0.22). Patients receiving ≥60 mg/kg/day had greater probability of achieving ratios ≥400. There were no significant differences in median dose (p = 0.8), trough (p = 0.24), or AUC₂₄/MIC ratios (p = 0.07 and p = 0.6) between patients with treatment success and failure.

CONCLUSIONS

Treatment failure was lower than previously reported in children. AUC₂₄/MIC ratios ≥400 were frequently achieved but were not associated with treatment success, dose, or troughs. Prospective studies using standard definitions of vancomycin treatment failure are needed to understand treatment failure in children with MRSA bacteremia.

Differences in gram-positive bacterial colonization and antimicrobial resistance among children in a high income inequality setting

Background

Staphylococcus aureus and beta-hemolytic streptococci (BHS) diseases disproportionately affect populations in middle/low-income countries. To assess if this disparity is reflected in colonization by these organisms, we compared their colonization frequency among children from different socioeconomic status (SES) communities in a city with high income inequality.

Methods

Between May–August 2014, we collected nasal and throat swabs to investigate S. aureus and BHS colonization among children who attended private and public pediatric clinics. Patients were classified as high SES, middle/low SES, and slum residents. We investigated the antimicrobial resistance profile, the SCCmec types and the presence of PVL genes among methicillin-resistant S. aureus (MRSA). We also examined the antimicrobial resistance profile and serogroups of BHS.

Results

Of 598 children, 221 (37%) were colonized with S. aureus, of which 49 (22%) were MRSA. MRSA colonization was higher in middle/low SES (n = 18; 14%) compared with high SES (n = 17; 6%) and slum (n = 14; 8%) residents (p = 0.01). All MRSA strains were susceptible to clindamycin, nitrofurantoin, and rifampin. The highest non-susceptibility frequency (42.9%) was observed to erythromycin. SCCmec type V was only found in isolates from high SES children; types I and II were found only in middle/low SES children. Ten (20%) MRSA isolates carried PVL genes. Twenty-four (4%) children were BHS carriers. All BHS (n = 8) found in high SES children and six (67%) isolates from slum patients belonged to group A. All group B streptococci were from middle/low SES children, corresponding to five (71%) of the seven BHS isolated in this group. BHS isolates were susceptible to all drugs tested.

Conclusions

Children from different SES communities had distinct bacterial colonization profiles, including MRSA carriage. Public health officials/researchers should consider SES when assessing disease transmission and control measures.

Staphylococcus aureus Bacteremia in Children: Antibiotic Resistance and Mortality

BACKGROUND

Staphylococcus aureus (SA) is a major cause of bacteremia in children. Methicillin-resistant SA (MRSA) is considered a public health threat; however, the differences in the prognosis of children with methicillin-susceptible SA (MSSA) versus MRSA bacteremia are not well defined.

METHODS

Data from all SA bacteremia events in children (0-16 years) from 2002 to 2016 in a single Israeli tertiary center were collected. Positive cultures within 48 hours of hospitalization were considered community associated (CA). Those obtained afterward or from children hospitalized within the previous year were considered health-care associated (HA).

RESULTS

We recorded 427 events, 284 (66%) were HA, 64 (15%) were MRSA and 9 (2%) were CA-MRSA. There was no increase in MRSA during the study period. In-hospital, 30-day and 1-year mortality were 3% (12 cases), 3.5% (16 cases), and 12% (50 cases), respectively. A multivariable analysis controlling for demographics, admitting department and prior morbidity showed an increased 1-year mortality in children with HA bacteremia (hazard ratio [HR] 4.1; 95% confidence interval [CI]: 1.3-12) and prior chronic disease (HR 3.4; 95% CI 1.2 to 9.0). MRSA was not independently associated with increased one-year mortality compared with MSSA: HR (95% CI: 1.4 [0.6-3.1]).

CONCLUSIONS

Short-term pediatric mortality after SA bacteremia is low. HA-SA bacteremia has an increased long-term risk for mortality, particularly in children with chronic diseases. Our data suggest mortality was not increased for MRSA compared with MSSA bacteremia. The very low rate of CA-MRSA bacteremia justifies the current practice not to include glycopeptides in the empiric treatment of CA bacteremia in Israel.

Risk Factors for Complications in Children with Staphylococcus aureus Bacteremia

OBJECTIVES

To determine risk factors for complications in children with Staphylococcus aureus (S aureus) bacteremia, including methicillin resistance.

STUDY DESIGN

Single center, retrospective cohort study of children ≤18 years of age hospitalized with S aureus bacteremia. We compared clinical characteristics and outcomes between those with methicillin-sensitive S aureus (MSSA) and methicillin-resistant S aureus (MRSA) bacteremia. Multivariate regression models identified risk factors associated with developing complications and with longer duration of bacteremia.

RESULTS

We identified 394 episodes of S aureus bacteremia, 279 (70.8%) with MSSA, and 115 (29.2%) with MRSA. Primary site of infection was catheter-related in 34%, musculoskeletal in 30%, skin/soft tissue in 10.2%, pneumonia in 6.4%, and endovascular in 6.6%. Eight children (2.0%) died within 30 days because of S aureus bacteremia, 15 (3.5%) had recurrence within 30 days, and 38 (9.6%) had complications including septic emboli or a metastatic focus of infection. Methicillin resistance was associated with development of a complication (aOR 3.31; 95% CI 1.60-6.85), and catheter-related infections were less likely to be associated with a complication (aOR 0.40; 95% CI 0.15-1.03). In a Poisson regression analysis on duration of bacteremia, methicillin resistance, musculoskeletal infection, endovascular infection, black race, and delayed intervention for source control were significantly associated with longer duration of bacteremia.

CONCLUSIONS

In this cohort of children with S aureus bacteremia, MRSA infections ere associated with longer duration of bacteremia and a higher likelihood of complications.

Cardiac gene expression and function in a mouse model of community-acquired methicillin-resistant Staphylococcus aureus sepsis: Role of inflammatory caspases 1 and 11

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an important cause of invasive infections, including sepsis associated with myocardial dysfunction. Caspases 1 and 11, involved in activation of the inflammasome, have been shown to be critical in response to sepsis as well as myocardial dysfunction of numerous etiologies. We examined the survival, myocardial function, and production of inflammatory mediators in mice lacking caspases 1 and 11. Cas 1/11 KO mice demonstrated no significant difference in mortality or in cardiac shortening fraction relative to control mice. Cas 1/11 KO mice had significantly reduced upregulation of expression of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in the heart relative to control mice after CA-MRSA infection, as well as reduced serum production of IL-1β, TNF-α, and IL-6, with no difference in IL-10 production. Other inflammatory mediators beyond IL-1β, TNF-α, and IL-6 may be involved in myocardial dysfunction in CA-MRSA sepsis.

Practice Patterns of Providers for the Management of Staphylococcus aureus Bacteremia in Children: Results of an Emerging Infections Network Survey

We conducted a survey of pediatric infectious diseases providers in the Emerging Infections Network regarding the workup and treatment of children with Staphylococcus aureus bacteremia (SAB). We found significant practice variation in the management of children with SAB. These findings emphasize the need for further research to guide best practices.

Association of Vancomycin MIC and Molecular Characteristics with Clinical Outcomes in Methicillin-Susceptible Staphylococcus aureus Acute Hematogenous Osteoarticular Infections in Children

Strains of methicillin-resistant Staphylococcus aureus (MRSA), particularly those belonging to the USA300 pulsotype, have been well described to cause severe osteoarticular infections (OAIs). A vancomycin MIC of ≥1.5 μg/ml has been demonstrated to contribute to disease severity in adults with MRSA and even methicillin-susceptible S. aureus (MSSA) bacteremia. Little data exist describing the outcomes of MSSA OAIs in terms of molecular characteristics and vancomycin MIC. All patients/isolates were chosen from a surveillance study at Texas Children's Hospital (TCH). S. aureus OAI isolates were identified from 2011 to 2016 and subjected to vancomycin Etests, pulsed-field gel electrophoresis (PFGE), and PCR to determine Panton-Valentine leucocidin (PVL) production and agr group. Two hundred fifty-two cases of S. aureus OAI were identified; 183 cases were MSSA (72.6%). During the study period, a decrease in the proportion of cases secondary to MRSA was observed, declining from 37.8% to 15.9% (P = 0.02). Of the MSSA isolates, 26.2% and 23.5% were USA300 and PVL positive, respectively. An increase in the proportion of MSSA isolates with a vancomycin MIC of ≥1.5 μg/ml occurred in the study period (P = 0.004). In MSSA, an elevated vancomycin MIC was associated with multiple surgical procedures and venous thromboses, even when adjusting for empirical β-lactam use. An increase in vancomycin MIC was noted among isolates belonging to agr group 4 during the study period. Methicillin resistance is declining among S. aureus OAI isolates at TCH. Simultaneously, vancomycin Etest MICs are increasing among MSSA isolates. Vancomycin MICs of ≥2 μg/ml are associated with adverse clinical outcomes in MSSA irrespective of antibiotic choice, suggesting that this may be a surrogate for organism virulence.

Identification and antimicrobial resistance of pathogens in neonatal septicemia in China-A meta-analysis

OBJECTIVES

The purpose of this study was to analyze the distribution and antimicrobial resistance of common bacterial pathogens causing neonatal septicemia based on a systematic review of published studies in China.

METHODS

Articles on neonatal sepsis published in the Chinese literature from 2009 to 2014 were identified according to the inclusion and exclusion criteria. Data were extracted and analyzed using Comprehensive Meta-Analysis software.

RESULTS

A total of 71 studies were included, in which a total of 8080 bacterial species were isolated from culture-positive blood samples. The pooled distribution rates of common bacterial pathogens were as follows: Staphylococcus 67.1% (95% confidence interval (CI) 63.3-70.6%), Enterococcus 4.1% (95% CI 3.5-4.8%), Streptococcus 2.3% (95% CI 1.6-3.2%), Escherichia coli 7.4% (95% CI 6.4-8.7%), Klebsiella 6.5% (95% CI 5.2-8.2%), Enterobacterium 2.3% (95% CI 1.9-2.8%), Acinetobacter 1.6% (95% CI 1.3-2.0%), Pseudomonas 1.7% (95% CI 1.3-2.2%). Among the Staphylococcus aureus strains isolated, more than 60% were methicillin-resistant (MRSA). In addition, over 50% of the Gram-negative isolates, including Escherichia and Klebsiella, were resistant to the commonly used third-generation cephalosporins. Most of the Gram-positive and Gram-negative bacteria isolated were sensitive to aminoglycosides, especially amikacin.

CONCLUSIONS

It is concluded that Staphylococcus, especially coagulase-negative Staphylococcus, continues to be the principal organism responsible for neonatal septicemia in China; Enterobacteriaceae are common among the Gram-negative isolates. Significant numbers of MRSA and multidrug-resistant Gram-negative bacteria are being isolated as pathogens responsible for neonatal septicemia in China.