Epidemiology and Mortality of Staphylococcus aureus Bacteremia in Australian and New Zealand Children

Molecular Characteristics of Community-Associated Staphylococcus aureus Isolates From Pediatric Patients With Bloodstream Infections Between 2012 and 2017 in Shanghai, China

Staphylococcus aureus is known as an invasive human pathogen, resulting in significant morbidity and mortality worldwide; however, information on community-associated S. aureus (CA-SA) from bloodstream infections (BSI) in children in China remains scarce. This study aimed to investigate the molecular characteristics of 78 CA-SA isolates recovered from pediatric patients with BSI between 2012 and 2017 in Shanghai. All isolates including 51 (65.4%) methicillin-susceptible S. aureus (MSSA) and 27 (34.6%) methicillin-resistant S. aureus (MRSA) isolates were characterized based on antimicrobial resistance, virulence genes, multilocus sequence typing (MLST), spa, and SCCmec typing. A total of 18 distinct sequence types (STs) and 44 spa types were identified. ST188 and ST7 were the predominant MSSA clones and ST59-MRSA-SCCmecIV/V was the most common MRSA clone. Spa t189 (9.0%, 7/78) was the most common spa type. SCCmec types IV and V were observed at frequencies of 59.3 and 40.7%, respectively. Notably, 40 (51.3%) S. aureus BSI strains were multidrug resistant (MDR), and these were mostly resistant to penicillin, erythromycin, and clindamycin. MRSA strains were associated with substantially higher rates of resistance to multiple antibiotics than MSSA strains. Fifty (64.1%, 50/78) isolates, including 19 (70.3%) MRSA isolates, harbored ≥ 10 tested virulence genes, as evaluated in this study. Ten (37.0%) MRSA isolates and four (7.8%) MSSA isolates harbored the gene encoding Panton-Valentine leukocidin (PVL). Virulence genes analysis showed diversity in different clones; the seb-sek-seq genes were present in all ST59 strains, whereas the seg-sei-sem-sen-seo genes were present in different clones including ST5, ST20, ST22, ST25, ST26, ST30, ST121, and ST487 strains. In conclusion, this study revealed that community-associated S. aureus strains from BSI in children demonstrated considerable genetic diversity, and identified major genotypes of CA-MRSA and CA-MSSA, with a high prevalence of CA-MRSA. Furthermore, major genotypes were frequently associated with specific antimicrobial resistance and toxin gene profiles. Understanding the molecular characteristics of those strains might provide further insights regarding the spread of BSI S. aureus among children between communities in China.

Hospital-Onset Staphylococcus aureus Bacteremia Is A Better Measure Than MRSA Bacteremia for Assessing Infection Prevention: Evaluation of 50 US Hospitals

Of 500 hospital-onset Staphylococcus aureus bacteremia events (58% methicillin-susceptible S. aureus [MSSA]; 42% methicillin-resistant S. aureus [MRSA]), we found no significant differences in S. aureus bacteremia rates between medium-sized and large hospitals. However, the proportion of S. aureus bacteremia caused by MSSA was greater in medium-sized hospitals and did not correlate with MRSA bacteremia. Infect Control Hosp Epidemiol 2018;39:476-478.

Staphylococcus aureus bacteraemia and endocarditis - epidemiology and outcome: a review

PURPOSE

To review the epidemiology of Staphylococcus aureus bacteraemia (SAB) and endocarditis (SAE), and discuss the short- and long-term outcome.  Materials and methods: A literature review of the epidemiology of SAB and SAE.

RESULTS

The reported incidence of SAB in Western countries is 16-41/100,000 person-years. Increasing incidence has been observed in many regions, in Iceland by 27% during 1995-2008. The increase is believed to depend on changes in population risk factors and possibly better and more frequent utilization of diagnostic procedures. S. aureus is now the leading causes of infective endocarditis (IE) in many regions of the world. It accounts for 15-40% of all IE cases, and the majority of cases in people who inject drugs (PWID). Recently, the incidence of SAE in PWID in Stockholm, Sweden, was found to be 2.5/1000 person-years, with an in-hospital mortality of 2.5% in PWID as compared to 15% in non-drug users. The 30-day mortality associated with SAB amounts to 15-25% among adults in Western countries, but is lower in children (0-9%). Mortality associated with SAE is high (generally 20-30% in-hospital mortality), and symptomatic cerebral embolizations are common (12-35%). The 1-year mortality reported after SAB and SAE is 19-62% and reflects deaths from underlying diseases and complications caused by the infection. In a subset of SAE cases, valvular heart surgery is needed (15-45%), but active intravenous drug use seems to be a reason to refrain from surgery. Despite its importance, there are insufficient data on the optimal management of SAB and SAE, especially on the required duration of antibiotic therapy.  Conclusions: The epidemiology of SAB and SAE has been changing in the past decades. They still carry a substantial morbidity and mortality. Intensified studies on treatment are warranted for improving patient outcome.

Central venous catheter salvage in children with Staphylococcus aureus central line-associated bloodstream infection

BACKGROUND

Prompt central venous catheter (CVC) removal is currently recommended in children with Staphylococcus aureus central line-associated bloodstream infection (CLABSI). Our objective was to examine the outcome of attempted line salvage in children with S. aureus CLABSI and assess predictors of success.

METHODS

A single-institution, retrospective cohort study was performed of all children with S. aureus CLABSI between 2012 and 2015. Patients with and without immediate CVC removal (≤ 2 days after first positive culture) were compared. The primary outcome was failed CVC salvage (removal after 3+ days).

RESULTS

Seventy-seven children met criteria for S. aureus CLABSI. Immediate CVC removal was performed in 27.3% of patients. Among the 72.7% patients in whom CVC salvage was attempted, 78.6% were successful and 21.4% required delayed CVC removal. Malignancy, short gut syndrome, neutropenia, methicillin-resistant S. aureus, and line type were not associated with salvage failure. No associated morbidity or mortality occurred in patients with a failed salvage attempt. New or recurrent bacteremia occurred in five patients, but three were successfully salvaged a second time.

CONCLUSIONS

CVC salvage was feasible in the majority of children with S. aureus CLABSI and was not associated with significant complications or attributable mortality as reported in adults.

Epidemiology and hospital readmission associated with complications of Staphylococcus aureus bacteremia in pediatrics over a 25-year period

We sought to comprehensively assess the prevalence and outcomes of complications associated with Staphylococcus aureus bacteremia (SAB) in children. Secondarily, prevalence of methicillin resistance and outcomes of complications from methicillin-resistant S. aureus (MRSA) vs. methicillin-susceptible S. aureus SAB were assessed. This is a single-center cross-sectional study of 376 patients ⩽18 years old with SAB in 1990-2014. Overall, 197 (52%) patients experienced complications, the most common being osteomyelitis (33%), skin and soft tissue infection (31%), and pneumonia (25%). Patients with complications were older (median 3 vs. 0·7 years, P = 0·05) and more had community-associated SAB (66% vs. 34%, P = 0·001). Fewer patients with complications had a SAB-related emergency department or hospital readmission (10% vs. 19%, P = 0·014). Prevalence of methicillin resistance increased from 1990-1999 to 2000-2009, but decreased in 2010-2014. Complicated MRSA bacteremia resulted in more intensive care unit admissions (66% vs. 47%, P = 0·03) and led to increased likelihood of having ⩾2 foci (58% vs. 26%, P < 0·001). From multivariate analysis, community-associated SAB increased risk and concurrent infections decreased risk of complications (odds ratio (OR) 1·82 (1·1-3·02), P = 0·021) and (OR 0·58 (0·34-0·97), P = 0·038), respectively. In conclusion, children with SAB should be carefully evaluated for complications. Methicillin resistance remains associated with poor outcomes but have decreased in overall prevalence.

Epidemiology of blood culture-proven bacterial sepsis in children in Switzerland: a population-based cohort study

BACKGROUND

Sepsis is a leading cause of childhood mortality worldwide. We assessed population-based incidence and outcomes of blood culture-proven bacterial sepsis in children in Switzerland.

METHODS

We did a multicentre, prospective, cohort study at ten paediatric hospitals in Switzerland. We included neonates and children younger than 17 years with blood culture-proven bacterial sepsis. Children were eligible if they met criteria for systemic inflammatory response syndrome-according to 2005 paediatric consensus definition- at the time of blood culture sampling. Incidence was calculated by dividing the number of annual sepsis episodes in the study for the years 2012-15 by the end-of-year resident paediatric population in Switzerland. The primary outcome was in-hospital mortality in the first 30 days after sepsis onset.

FINDINGS

Between Sept 1, 2011, and Dec 31, 2015, we enrolled 1096 children to our study. Of 1181 episodes of blood culture-proven bacterial sepsis, 382 (32%) occurred in 379 previously healthy children, 402 (34%) in 391 neonates, and 397 (34%) in 341 children with comorbidities. Incidence was 25·1 cases per 100 000 (95% CI 23·8-26·4) in children and 146·0 cases per 100 000 (133·2-159·6) in neonates. Central line-associated bloodstream infections and primary bloodstream infections accounted for 569 (48%) of 1181 episodes, and organ dysfunction was present in 455 (39%) of 1181 episodes. Escherichia coli (242 of 1181 [20%]), Staphylococcus aureus (177 of 1181 [15%]), coagulase-negative staphylococci (135 of 1181 [11%]), and Streptococcus pneumoniae (118 of 1181 [10%]) were the most prevalent pathogens in our study, accounting for 57% of episodes. The overall case-fatality ratio was 7% (82 of 1181 episodes; 95% CI 5·6-8·6), and it was higher in neonates (11%, 45 of 402 episodes; 8·4-14·8; adjusted odds ratio [OR] 4·41, 95% CI 1·75-11·1) and children with comorbidities (7%, 27 of 397 episodes; 4·6-9·9; OR 4·97, 1·84-13·4) compared with previously healthy children (3%, ten of 382 episodes; 1·3-4·9). The case-fatality ratio was 1% (five of 726 episodes [95% CI 0·3-1·7]) for children without organ dysfunction, which increased to 17% (77 of 455 episodes [13·7-20·8]) when organ dysfunction was present (adjusted OR 4·84, 95% CI 1·40-16·7).

INTERPRETATION

The burden of blood culture-proven bacterial sepsis on child health remains considerable. We recorded key differences in predominant organisms, severity, and outcome between neonates, previously healthy children, and children with comorbidities. Although for most episodes of blood culture-proven bacterial sepsis, no organ dysfunction was seen, presence of organ dysfunction was strongly associated with mortality.

FUNDING

Swiss National Science Foundation, Swiss Society of Intensive Care, Bangerter Foundation, Vinetum and Borer Foundation, and Foundation for the Health of Children and Adolescents.

Are scabies and impetigo "normalised"? A cross-sectional comparative study of hospitalised children in northern Australia assessing clinical recognition and treatment of skin infections

BACKGROUND

Complications of scabies and impetigo such as glomerulonephritis and invasive bacterial infection in Australian Aboriginal children remain significant problems and the overall global burden of disease attributable to these skin infections remains high despite the availability of effective treatment. We hypothesised that one factor contributing to this high burden is that skin infection is under-recognised and hence under-treated, in settings where prevalence is high.

METHODS

We conducted a prospective, cross-sectional study to assess the burden of scabies, impetigo, tinea and pediculosis in children admitted to two regional Australian hospitals from October 2015 to January 2016. A retrospective chart review of patients admitted in November 2014 (mid-point of the prospective data collection in the preceding year) was performed. Prevalence of documented skin infection was compared in the prospective and retrospective population to assess clinician recognition and treatment of skin infections.

RESULTS

158 patients with median age 3.6 years, 74% Aboriginal, were prospectively recruited. 77 patient records were retrospectively reviewed. Scabies (8.2% vs 0.0%, OR N/A, p = 0.006) and impetigo (49.4% vs 19.5%, OR 4.0 (95% confidence interval [CI 2.1-7.7) were more prevalent in the prospective analysis. Skin examination was only documented in 45.5% of cases in the retrospective review. Patients in the prospective analysis were more likely to be prescribed specific treatment for skin infection compared with those in the retrospective review (31.6% vs 5.2%, OR 8.5 (95% CI 2.9-24.4).

CONCLUSIONS

Scabies and impetigo infections are under-recognised and hence under-treated by clinicians. Improving the recognition and treatment of skin infections by clinicians is a priority to reduce the high burden of skin infection and subsequent sequelae in paediatric populations where scabies and impetigo are endemic.

Diffusion of clindamycin-resistant and erythromycin-resistant methicillin-susceptible Staphylococcus aureus (MSSA), potential ST398, in United States Veterans Health Administration Hospitals, 2003-2014

Background

Changing phenotypic profiles of methicillin-susceptible Staphylococcus aureus (MSSA) isolates can indicate the emergence of novel sequence types (ST). The diffusion of MSSA ST can be tracked by combining established genotypic profiles with phenotypic surveillance data. ST398 emerged in New York City (NYC) and exhibits resistance to clindamycin and erythromycin but tetracycline susceptibility (“potential ST398”). Trends of potential ST398 were examined in a national cohort of all Veterans Health Administration patients with MSSA invasive infections during 2003–2014.

Methods

A retrospective cohort of all patients with MSSA invasive infections, defined as a positive clinical culture from a sterile site, during 2003–2014 was created. Only isolates tested against clindamycin, erythromycin and tetracycline were included. Annual hospital-level proportions of potential ST398 were compared according to facility distance from NYC and region.

Results

A total of 34,025 patient isolates from 136 VA medical centers met the inclusion criteria. Of those, 4582 (13.5%) met the definition of potential ST398. Potential ST398 increased over the 12-year cohort and diffused outwards from NYC. Incidence Rate Ratios of >1.0 (p < 0.01) reflect increases in potential ST398 over time in hospitals nearer to NYC.

Conclusions

We observe an increase in the phenotypic profile of potential ST398 MSSA isolates in invasive infections in a national cohort of patients in the US. The increase is not evenly distributed across the US but appears to diffuse outwards from NYC. Novel MSSA strain emergence may have important clinical implications, particularly for the use of clindamycin for suspected S. aureus infections.

Encouraging rational antibiotic use in childhood pneumonia: a focus on Vietnam and the Western Pacific Region

Globally, pneumonia is considered to be the biggest killer of infants and young children (aged <5 years) outside the neonatal period, with the greatest disease burden in low- and middle-income countries. Optimal management of childhood pneumonia is challenging in settings where clinicians have limited information regarding the local pathogen and drug resistance profiles. This frequently results in unnecessary and poorly targeted antibiotic use. Restricting antibiotic use is a global priority, particularly in Asia and the Western Pacific Region where excessive use is driving high rates of antimicrobial resistance. The authors conducted a comprehensive literature review to explore the antibiotic resistance profile of bacteria associated with pneumonia in the Western Pacific Region, with a focus on Vietnam. Current management practices were also considered, along with the diagnostic dilemmas faced by doctors and other factors that increase unnecessary antibiotic use. This review offers some suggestions on how these issues may be addressed.

A Retrospective Study of the Impact of Rapid Diagnostic Testing on Time to Pathogen Identification and Antibiotic Use for Children with Positive Blood Cultures

Introduction

Rapid identification of bloodstream pathogens provides crucial information that can improve the choice of antimicrobial therapy for children. Previous impact studies have primarily focused on adults. Our objective was to evaluate the impact of rapid testing in a children’s hospital on time to organism identification and antibiotic use in the setting of an established antimicrobial stewardship program.

Methods

We conducted a retrospective study over three consecutive time periods (spanning January 2013–August 2015) as our hospital sequentially introduced two rapid testing methods for positive blood cultures. An antimicrobial stewardship program was active throughout the study. In the baseline period, no rapid diagnostic methods were routinely utilized. In the second period (PNAFISH), a fluorescent in situ hybridization test was implemented for gram-positive organisms and in the third a rapid multiplex PCR (rmPCR) test was employed. For children with positive blood cultures, time to organism identification use and duration of select antimicrobial therapies were compared between periods.

Results

Positive blood cultures were analyzed. Median overall time to organism identification was 23, 11, and 0 h in the baseline, PNAFISH, and rmPCR periods, respectively (p < 0.001 for both PNAFISH and rmPCR vs. baseline). For gram-negative organisms, only rmPCR performed significantly faster than baseline (p < 0.001). The duration of vancomycin use for coagulase-negative staphylococci was shorter in both the PNAFISH and rmPCR periods (mean 31 h in the baseline period, 12 and 14 h in the PNAFISH and rmPCR periods, respectively). For MSSA bacteremia, use of vancomycin was significantly decreased only in the rmPCR period (32% of patients vs. 64 and 72% in the baseline and PNAFISH periods; mean duration of 9 h vs. 30 and 26 h). There was no difference in use or duration of broad-spectrum gram-negative therapy across the three time periods.

Conclusion

Rapid diagnostic testing for children with positive blood cultures results in faster time to identification and can influence antibiotic prescribing in the setting of active antimicrobial stewardship particularly for gram-positive pathogens.

Funding

Merck.