Antimicrobial Nonsusceptibility of Gram-Negative Bloodstream Isolates, Veterans Health Administration System, United States, 2003-20131

14-Year Epidemiologic study of Pseudomonas aeruginosa bloodstream infection incidence and resistance in the Veterans Health Administration system, 2009-2022

Background

Multidrug resistant Pseudomonas aeruginosa (PA) represents a serious threat to hospitalized patients. Characterizing the incidence of PA infection and degree of resistance can inform empiric treatment and preventative measures.

Objectives

We sought to describe trends in incidence and resistance characteristics of PA bloodstream infections (BSI) observed within the Veterans Health Administration (VHA) system and identify factors contributing to higher observed mortality within this population.

Methods

We characterized demographic and clinical features of unique patients among the VHA population presenting with their first episode of PA-BSI between 2009 and 2022 and summarized trends related to mortality and resistance phenotype based on year and geographical location. We additionally used logistic regression analysis to identify predictors of 30-day mortality among this cohort.

Results

We identified 8039 PA-BSIs during the study period, 32.7% of which were hospital onset. Annual PA-BSI cases decreased by 35.8%, and resistance among all antimicrobial classes decreased during the study period, while the proportion of patients receiving early active treatment based on susceptibility testing results increased. Average 30-day mortality rate was 23.3%. Higher Charlson Comorbidity Index, higher mAPACHE score, VHA facility complexity 1b and hospital-onset cases were associated with higher mortality, and early active treatment was associated with lower mortality.

Conclusions

PA-BSI resistance decreased across the VHA system during the study period. Further investigation of antimicrobial stewardship measures possibly contributing to the observed decreased resistance in this cohort and identification of measures to improve on the high mortality associated with PA-BSI in the VHA population is warranted.

The bacterial genetic determinants of Escherichia coli capacity to cause bloodstream infections in humans

Escherichia coli is both a highly prevalent commensal and a major opportunistic pathogen causing bloodstream infections (BSI). A systematic analysis characterizing the genomic determinants of extra-intestinal pathogenic vs. commensal isolates in human populations, which could inform mechanisms of pathogenesis, diagnostic, prevention and treatment is still lacking. We used a collection of 912 BSI and 370 commensal E. coli isolates collected in France over a 17-year period (2000-2017). We compared their pangenomes, genetic backgrounds (phylogroups, STs, O groups), presence of virulence-associated genes (VAGs) and antimicrobial resistance genes, finding significant differences in all comparisons between commensal and BSI isolates. A machine learning linear model trained on all the genetic variants derived from the pangenome and controlling for population structure reveals similar differences in VAGs, discovers new variants associated with pathogenicity (capacity to cause BSI), and accurately classifies BSI vs. commensal strains. Pathogenicity is a highly heritable trait, with up to 69% of the variance explained by bacterial genetic variants. Lastly, complementing our commensal collection with an older collection from 1980, we predict that pathogenicity continuously increased through 1980, 2000, to 2010. Together our findings imply that E. coli exhibit substantial genetic variation contributing to the transition between commensalism and pathogenicity and that this species evolved towards higher pathogenicity.

Evaluating the long-term portrayal of antibiotic resistance in major U.S. newspapers

BACKGROUND

Popular media play a critical role in informing the public about antibiotic resistance, which has remained a health concern for over seven decades. Media attention increases the notoriety of antibiotic resistance and shapes the public's perception of its severity, causes, and solutions. Therefore, it is critical the media accurately portray scientific knowledge that may shape personal and policy responses to antibiotic resistance.

METHODS

We analyzed articles from two major U.S. newspapers, The New York Times and Los Angeles Times, from 1940 to 2019 to assess trends in sentiment and lexicon surrounding antibiotic and antimicrobial resistance.

RESULTS

We observed a gradual increase in the number of relevant articles about resistance, although far fewer than other topics with comparable mortality rates. We found a consistently threatening portrayal of antibiotic resistance as a crisis, reflected in the usage of terms such as "superbug" to refer to some pathogens. Governmental agencies responsible for determining antibiotic usage policies were infrequently mentioned in articles. Blame for resistance was almost exclusively attributed to inappropriate antibiotic use, mainly in animals, rather than appropriate uses of antibiotics.

CONCLUSIONS

Collectively, our results provide insights into how popular media can more accurately inform the public about antibiotic resistance. Potential changes include increasing news coverage, avoiding fear-mongering, and adequately conveying the multiple uses of antibiotics that can potentiate resistance.

Synthesis of silver nanoparticles using Emilia sonchifolia plant for treatment of bloodstream diseases caused by Escherichia coli

OBJECTIVES

Among infectious diseases, bloodstream infection (BSI) caused by gram-negative bacteria (E. coli) is the leading cause of death worldwide. However, the bacteria have produced resistance to many of these antibiotics. Thus, the present study aimed to develop silver nanoparticles (AgNPs) loaded with Emilia sonchifolia (ES) extract (ES-AgNPs) to treat BSI efficiently.

METHODS

AgNPs were synthesized by reduction of silver nitrate (AgNO₃) solution by ES extract. Furthermore, these ES-AgNPs were characterized for particle size and zeta potential, crystallinity by powder X-ray diffraction (P-XRD) technique, in vitro antibacterial activity, time-kill assay, film bio adhesion, and fluorescence assay.

RESULTS

Surface plasmon resonance (SPR) has been used to confirm the formation of AgNPs by seeing a shift in colour to dark-brown. The ES-AgNPs displayed a mean particle size of 137±3nm (PDI of 0.168±0.02) and zeta potential of 18.2±0.8mV. Furthermore, according to P-XRD results, the developed AgNPs are highly crystalline. The ES-AgNPs showed effective antibacterial action against E. coli with minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of 0.4±0.02μg/mL and 0.8±0.03μg/mL, respectively. In addition, ES-AgNPs inhibited biofilm formation and bacterial adhesion in a dose-dependent manner with 100% inhibition obtained in 48h at MBC.

CONCLUSIONS

Present research work revealed that the ES-AgNPs obtained by green synthesis holds a prominent antibacterial activity in the treatment of BSIs caused by E. coli and they may be used as a competent substitute for current treatments. However, further, in vivo antibacterial studies are required to establish its efficacy in the treatment of BSIs.

The Population Genomics of Increased Virulence and Antibiotic Resistance in Human Commensal Escherichia coli over 30 Years in France

Escherichia coli is a commensal species of the lower intestine but is also a major pathogen causing intestinal and extraintestinal infections that is increasingly prevalent and resistant to antibiotics. Most studies on genomic evolution of E. coli used isolates from infections. Here, instead, we whole-genome sequenced a collection of 403 commensal E. coli isolates from fecal samples of healthy adult volunteers in France (1980 to 2010). These isolates were distributed mainly in phylogroups A and B2 (30% each) and belonged to 152 sequence types (STs), the five most frequent being ST10 (phylogroup A; 16.3%), ST73 and ST95 (phylogroup B2; 6.3 and 5.0%, respectively), ST69 (phylogroup D; 4.2%), and ST59 (phylogroup F; 3.9%), and 224 O:H serotypes. ST and serotype diversity increased over time. The O1, O2, O6, and O25 groups used in bioconjugate O-antigen vaccine against extraintestinal infections were found in 23% of the strains of our collection. The increase in frequency of virulence-associated genes and antibiotic resistance was driven by two evolutionary mechanisms. Evolution of virulence gene frequency was driven by both clonal expansion of STs with more virulence genes ("ST-driven") and increases in gene frequency within STs independent of changes in ST frequencies ("gene-driven"). In contrast, the evolution of resistance was dominated by increases in frequency within STs ("gene-driven"). This study provides a unique picture of the phylogenomic evolution of E. coli in its human commensal habitat over 30 years and will have implications for the development of preventive strategies. IMPORTANCE Escherichia coli is an opportunistic pathogen with the greatest burden of antibiotic resistance, one of the main causes of bacterial infections and an increasing concern in an aging population. Deciphering the evolutionary dynamics of virulence and antibiotic resistance in commensal E. coli is important to understand adaptation and anticipate future changes. The gut of vertebrates is the primary habitat of E. coli and probably where selection for virulence and resistance takes place. Unfortunately, most whole-genome-sequenced strains are isolated from pathogenic conditions. Here, we whole-genome sequenced 403 E. coli commensals isolated from healthy French subjects over a 30-year period. Virulence genes increased in frequency by both clonal expansion of clones carrying them and increases in frequency within clones, whereas resistance genes increased by within-clone increased frequency. Prospective studies of E. coli commensals should be performed worldwide to have a broader picture of evolution and adaptation of this species.

Epidemiology of Antimicrobial Resistance Among Blood and Respiratory Specimens in the United States Using Genotypic Analysis from a Cloud-Based Population Surveillance Network

Background

Antimicrobial resistance (AMR) surveillance is critical in informing strategies for infection control in slowing the spread of resistant organisms and for antimicrobial stewardship in the care of patients. However, significant challenges exist in timely and comprehensive AMR surveillance.

Methods

Using BioFire Pneumonia and Blood Culture 2 Panels data from BioFire Syndromic Trends (Trend), a cloud-based population surveillance network, we described the detection rate of AMR among a US cohort. Data were included from 2019 to 2021 for Gram-positive and -negative organisms and their related AMR genomic-resistant determinants as well as for detections of Candida auris. Regional and between panel AMR detection rate differences were compared. In addition, AMR codetections and detection rate per organism were evaluated for Gram-negative organisms.

Results

A total of 26 912 tests were performed, primarily in the Midwest. Overall, AMR detection rate was highest in the South and more common for respiratory specimens than blood. methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus detection rates were 34.9% and 15.9%, respectively, whereas AMR for Gram-negative organisms was lower with 7.0% CTX-M and 2.9% carbapenemases. In addition, 10 mcr-1 and 4 C auris detections were observed. For Gram-negative organisms, Klebsiella pneumoniae and Escherichia coli were most likely to be detected with an AMR gene, and of Gram-negative organisms, K pneumoniae was most often associated with 2 or more AMR genes.

Conclusions

Our study provides important in-depth evaluation of the epidemiology of AMR among respiratory and blood specimens for Gram-positive and -negative organism in the United States. The Trend surveillance network allows for near real-time surveillance of AMR.

Antimicrobial resistance among Enterobacteriaceae, Staphylococcus aureus, and Pseudomonas spp. isolates from clinical specimens from a hospital in Nairobi, Kenya

Background

Antimicrobial resistance among pathogens of public health importance is an emerging problem in sub-Saharan Africa. Unfortunately, published information on the burden and patterns of antimicrobial resistance (AMR) in this region is sparse. There is evidence that the burden and patterns of AMR vary by geography and facility. Knowledge of local epidemiology of AMR is thus important for guiding clinical decisions and mitigation strategies. Therefore, the objective of this study was to determine the burden and predictors of AMR and multidrug resistance (MDR) among bacterial pathogens isolated from specimens submitted to the diagnostic laboratory of a hospital in Nairobi, Kenya.

Methods

This retrospective study used laboratory records of 1,217 clinical specimens submitted for bacterial culture and sensitivity testing at the diagnostic laboratory of The Karen Hospital in Nairobi, Kenya between 2012 and 2016. Records from specimens positive for Enterobacteriaceae, Staphylococcus aureus, or Pseudomonas spp. isolates were included for analysis. Firth logistic models, which minimize small sample bias, were used to investigate determinants of AMR and MDR of the isolates.

Results

A total of 222 specimens had bacterial growth. Most Enterobacteriaceae isolates were resistant to commonly used drugs such as penicillin/β-lactamase inhibitor combinations (91.2%) and folate pathway inhibitors (83.7%). Resistance to extended-spectrum cephalosporins was also high (52.9%). Levels of AMR and MDR for Enterobacteriaceae were 88.5% and 51%, respectively. Among S. aureus isolates, 57.1% were AMR, while 16.7% were MDR. As many as 42.1% of the Pseudomonas spp. isolates were aminoglycoside-resistant and 15% were fluoroquinolone-resistant, but none exhibited resistance to antipseudomonal carbapenems. Half of Pseudomonas spp. isolates were AMR but none were MDR. Significant predictors of MDR among Enterobacteriaceae were organism species (p = 0.002) and patient gender (p = 0.024).

Conclusions

The high levels of extended-spectrum cephalosporin resistance and MDR among Enterobacteriaceae isolates are concerning. However, the relatively low levels of MDR S. aureus, and an absence of carbapenem resistance among Pseudomonas isolates, suggests that last-line drugs are still effective against S. aureus and Pseudomonas infections. These findings are relevant for guiding evidence-based treatment decisions as well as surveillance efforts and directions for future research, and contribute to the sparse literature on AMR in sub-Saharan Africa.

Desirability of Outcome Ranking for the Management of Antimicrobial Therapy (DOOR MAT): A Framework for Assessing Antibiotic Selection Strategies in the Presence of Drug Resistance

The complexities of antibiotic resistance mean that successful stewardship must consider both the effectiveness of a given antibiotic and the spectrum of that therapy to minimize imposing further selective pressure. To meet this challenge, we propose the Desirability of Outcome Ranking approach for the Management of Antimicrobial Therapy (DOOR MAT), a flexible quantitative framework that evaluates the desirability of antibiotic selection. Herein, we describe the steps required to implement DOOR MAT and present examples to illustrate how the desirability of treatment selection can be evaluated using resistance information. While treatments and the scoring of treatment selections must be adapted to specific clinical settings, the principle of DOOR MAT remains constant: The most desirable antibiotic choice effectively treats the patient while exerting minimal pressure on future resistance.

The Desirability of Outcome Ranking for the Management of Antimicrobial Therapy (DOOR MAT) Reveals Improvements in the Treatment of Bloodstream Infection Caused by Escherichia coli and Klebsiella pneumoniae in Patients from the Veterans Health Administration

BACKGROUND

Reductions in the use of broad-spectrum antibiotics is a cornerstone of antimicrobial stewardship. We aim to demonstrate the use of Desirability of Outcome Ranking Approach for the Management of Antimicrobial Therapy (DOOR MAT) to evaluate the treatment of Escherichia coli and Klebsiella pneumoniae bloodstream infection in patients from the Veterans Health Administration (VHA) across a decade.

METHODS

Using electronic records, we determined empiric and definitive antibiotic treatments, clinical characteristics and 30-day mortality of subjects with monomicrobial E. coli and K. pneumoniae bloodstream infection hospitalized in VHA medical centers from 2009 to 2018. Focusing on patients treated with parenteral β-lactams and with available antibiotic susceptibility testing results, we applied a range of DOOR MAT scores that reflect the desirability of antibiotic choices according to spectrum and activity against individual isolates. We report trends in resistance and desirability of empiric and definitive antibiotic treatments.

RESULTS

During the 10-year period analyzed, resistance to expanded-spectrum cephalosporins and fluoroquinolones increased in E. coli but not in K. pneumoniae, while resistance remained unchanged to carbapenems and piperacillin-tazobactam. In 6,451 cases analyzed, we observed improvements in DOOR MAT scores consistent with de-escalation. Improvement in desirability of definitive treatment compared to empiric treatment occurred in 26% of cases, increasing from 16% in 2009 to 34% in 2018. Reductions in overtreatment were sustained and without negative impact on survival.

CONCLUSION

DOOR MAT provides a framework to assess antibiotic treatment of E. coli and K. pneumoniae bloodstream infection and can be a useful metric in antimicrobial stewardship.

Epidemiology and Risk Factors Associated With Mortality in Consecutive Patients With Bacterial Bloodstream Infection: Impact of MDR and XDR Bacteria

Background

 Mortality related to bloodstream infections (BSIs) is high. The epidemiology of BSIs is changing due to the increase in multidrug resistance, and it is unclear whether the presence of multidrug-resistant (MDR) organisms, per se, is an independent risk factor for mortality. Our objectives were, first, to describe the epidemiology and outcome of BSIs and, second, to determine the risk factors associated with mortality among patients with BSI.

Methods

 This research used a single-center retrospective observational study design. Patients were identified through microbiological reports. Data on medical history, clinical condition, bacteria, antimicrobial therapy, and mortality were collected. The primary outcome was crude mortality at 30 days. The relationships between mortality and demographic, clinical, and microbiological variables were analyzed by multivariate analysis.

Results

 A total of 1049 inpatients were included. MDR bacteria were isolated in 27.83% of patients, where 2.14% corresponded to an extremely drug-resistant (XDR) isolate. The crude mortality rates at days 7, 30, and 90 were 12.11%, 25.17%, and 36.13%, respectively. Pitt score >2, lung and abdomen as site of infection, and XDR Pseudomonas aeruginosa were independent risk factors for 7-, 30-, and 90-day mortality. Charlson score >4, carbapenem-resistant Klebsiella pneumoniae, and XDR Acinetobacter baumannii were independent risk factors for 30- and 90-day mortality. Infection by XDR gram-negative bacteria, Charlson score >4, and immunosuppression were independent risk factors for mortality in patients who were stable at the time of BSI.

Conclusions

 BSI is an event with an extreme impact on mortality. Patients with severe clinical condition are at higher risk of death. The presence of XDR gram-negative bacteria in blood is strongly and independently associated with patient death.

How Far We've Come, How Far We Have to Go: a Review of Advances in Antimicrobial Stewardship in the Veterans Health Administration

PURPOSE OF REVIEW

This review highlights several of the successes in antimicrobial stewardship seen in the largest integrated healthcare system in the USA, the Veterans Health Administration.

RECENT FINDINGS

Since deploying antimicrobial stewardship programs on a national scale in the Veterans Health Administration, decreases in overall antimicrobial use and Clostridioides difficile infections have been observed. Concurrent infection prevention initiatives have also contributed to these improvements in the Veterans Health Administration.

SUMMARY

By embracing multidisciplinary stewardship teams, focusing on education and research in the field of antimicrobial stewardship, and leveraging the vast data available within the national system, the Veterans Health Administration has made substantial advances in antimicrobial stewardship.

Epidemiology of Bloodstream Infections in Hospitalized Children in the United States, 2009-2016

BACKGROUND

Bloodstream infections (BSIs) cause significant morbidity and mortality in children. Recent pediatric epidemiological data may inform prevention strategies and empiric antimicrobial therapy selection.

METHODS

We conducted a retrospective cohort study from 2009 through 2016 utilizing demographic and microbiologic data on inpatients aged <19 years using the Premier Healthcare Database. BSIs were positive blood cultures without known contaminants. Hospitalization rate was the number of BSI-positive encounters per 1000 admissions. Community-acquired infections (CAIs) were cultures positive ≤2 days of admission among nonneonates. BSI patients were compared to documented positive BSI patients (non-BSI); differences were analyzed using χ2 test, t test, and Cochran-Armitage test for time trends.

RESULTS

Among 1 809 751 encounters from 162 US hospitals, 5340 (0.30%) were BSI positive; CAIs were most common (50%). BSI patients were more often aged 1-5 years and had complex chronic conditions or central lines compared to non-BSI patients. The BSI hospitalization rate declined nonsignificantly over time (3.13 in 2009 to 2.98 in 2016, P = .08). Among pathogens, Escherichia coli (0.80 to 1.26), methicillin-sensitive Staphylococcus aureus (0.83 to 1.98), and group A Streptococcus (0.16 to 0.37) significantly increased for nonneonates, while Streptococcus pneumoniae (1.07 to 0.26) and Enterococcus spp. (0.60 to 0.17) declined. Regional differences were greatest for E. coli and highest in the New England and South Atlantic regions.

CONCLUSIONS

Trends in pediatric BSI hospitalization rates varied by pathogen and regionally. Overall the BSI hospitalization rate did not significantly decline, indicating a continued need to improve pediatric BSI assessment and prevention.

Multidrug-Resistant Bacterial Infections in U.S. Hospitalized Patients, 2012-2017

BACKGROUND

Multidrug-resistant (MDR) bacteria that are commonly associated with health care cause a substantial health burden. Updated national estimates for this group of pathogens are needed to inform public health action.

METHODS

Using data from patients hospitalized in a cohort of 890 U.S. hospitals during the period 2012-2017, we generated national case counts for both hospital-onset and community-onset infections caused by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus (VRE), extended-spectrum cephalosporin resistance in Enterobacteriaceae suggestive of extended-spectrum beta-lactamase (ESBL) production, carbapenem-resistant Enterobacteriaceae, carbapenem-resistant acinetobacter species, and MDR Pseudomonas aeruginosa.

RESULTS

The hospital cohort in the study accounted for 41.6 million hospitalizations (>20% of U.S. hospitalizations annually). The overall rate of clinical cultures was 292 cultures per 1000 patient-days and was stable throughout the time period. In 2017, these pathogens caused an estimated 622,390 infections (95% confidence interval [CI], 579,125 to 665,655) among hospitalized patients. Of these infections, 517,818 (83%) had their onset in the community, and 104,572 (17%) had their onset in the hospital. MRSA and ESBL infections accounted for the majority of the infections (52% and 32%, respectively). Between 2012 and 2017, the incidence decreased for MRSA infection (from 114.18 to 93.68 cases per 10,000 hospitalizations), VRE infection (from 24.15 to 15.76 per 10,000), carbapenem-resistant acinetobacter species infection (from 3.33 to 2.47 per 10,000), and MDR P. aeruginosa infection (from 13.10 to 9.43 per 10,000), with decreases ranging from -20.5% to -39.2%. The incidence of carbapenem-resistant Enterobacteriaceae infection did not change significantly (from 3.36 to 3.79 cases per 10,000 hospitalizations). The incidence of ESBL infection increased by 53.3% (from 37.55 to 57.12 cases per 10,000 hospitalizations), a change driven by an increase in community-onset cases.

CONCLUSIONS

Health care-associated antimicrobial resistance places a substantial burden on patients in the United States. Further work is needed to identify improved interventions for both the inpatient and outpatient settings. (Funded by the Centers for Disease Control and Prevention.).

Synthetic molecular evolution of host cell-compatible, antimicrobial peptides effective against drug-resistant, biofilm-forming bacteria

Novel classes of antibiotics and new strategies to prevent and treat infections are urgently needed because the rapid rise in drug-resistant bacterial infections in recent decades has been accompanied by a parallel decline in development of new antibiotics. Membrane permeabilizing antimicrobial peptides (AMPs) have long been considered a potentially promising, novel class of antibiotic, especially for wound protection and treatment to prevent the development of serious infections. Yet, despite thousands of known examples, AMPs have only infrequently proceeded as far as clinical trials, especially the chemically simple, linear examples. In part, this is due to impediments that often limit their applications in vivo. These can include low solubility, residual toxicity, susceptibility to proteolysis, and loss of activity due to host cell, tissue, and protein binding. Here we show how synthetic molecular evolution can be used to evolve potentially advantageous antimicrobial peptides that lack these impediments from parent peptides that have at least some of them. As an example of how the antibiotic discovery pipeline can be populated with more promising candidates, we evolved and optimized one family of linear AMPs into a new generation with high solubility, low cytotoxicity, potent broad-spectrum sterilizing activity against a panel of gram-positive and gram-negative ESKAPE pathogens, and antibiofilm activity against gram-positive and gram-negative biofilms. The evolved peptides have these activities in vitro even in the presence of concentrated host cells and also in vivo in the complex, cell- and protein-rich environment of a purulent animal wound model infected with drug-resistant bacteria.

Rapid molecular tests for detection of antimicrobial resistance determinants in Gram-negative organisms from positive blood cultures: a systematic review and meta-analysis

BACKGROUND

Timely detection of antimicrobial (cephalosporin/carbapenem) resistance (AMR) determinants is crucial to the clinical management of bloodstream infections caused by Gram-negative bacteria (GNB).

OBJECTIVES

To review and meta-analyse the evidence for using commercially available molecular tests for the direct detection of AMR determinants in GNB-positive blood cultures (PBCs).

DATA SOURCES

PubMed, Scopus and ISI Web of Knowledge.

STUDY ELIGIBILITY CRITERIA

Clinical studies evaluating the performance of two major commercial systems, namely the Verigene® and FilmArray® systems, for rapid testing of GNB-PBCs, in comparison with the phenotypic or genotypic methods performed on GNB-PBC isolates.

METHODS

Literature search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria and, for meta-analysis of sensitivity and specificity of both systems, bivariate random-effects model.

RESULTS

Twenty studies were identified (3310 isolates) from 2006 to 2019. Nine studies were conducted in East Asia. In 15 studies using phenotypic comparators (1930 isolates), 1014 (52.5%) isolates were Escherichia coli, and 287 (14.9%) of all the isolates displayed AMR phenotypes. In five studies using genotypic comparators (1380 isolates), 585 (42.4%) were E. coli, and 100 (7.2%) of all the isolates displayed AMR genotypes. Pooled sensitivity and specificity estimates for detection of AMR determinants by the Verigene (i.e. CTX-M, IMP, KPC, NDM, OXA and VIM) and/or FilmArray (i.e. KPC) systems were 85.3% (95% CI 79.9%-89.4%) and 99.1% (95% CI 98.2%-99.5%), respectively, across the 15 studies, and 95.5% (95% CI 89.2%-98.2%) and 99.7% (95% CI 99.1%-99.9%), respectively, across the five studies.

CONCLUSIONS

Our findings show that the Verigene and FilmArray systems may be a valid adjunct to the conventional microbiology (phenotypic or genotypic) methods used to identify AMR in GNBs. The FilmArray system detects only one AMR genotype, namely KPC, limiting its use. Both Verigene and FilmArray systems can miss important cephalosporin/carbapenem resistance phenotypes in a minority of cases. However, the sensitivity and specificity of both systems render them valuable clinical tools in timely identification of resistant isolates. Further studies will establish the prominence of such rapid diagnostics as standard of care in individuals with bloodstream infections.

Comparison of the Clinical Characteristics of Hospital-Acquired and Non-Hospital-Acquired Acinetobacter calcoaceticus-baumannii Complex in a Large Midwest US Health Care System

We retrospectively compared the clinical characteristics of hospital-acquired (HA) vs non-hospital-acquired (nHA) Acinetobacter calcoaceticus-baumannii complex isolates in a large health care system in St. Louis, Missouri, from 2007 to 2017. More than 60% of the total isolates were nHA; they were predominantly from nonrespiratory sources and exhibited ~40% carbapenem resistance rates and stably persisted, though HA occurrence waned.

The Epidemiology of Bloodstream Infections and Antimicrobial Susceptibility Patterns: A Nine-Year Retrospective Study at St. Dominic Hospital, Akwatia, Ghana

Background

Bloodstream infections are among the top causes of morbidity and mortality in people of all ages, especially in immunocompromised patients in sub-Saharan Africa. This study aimed at describing the epidemiology of bloodstream infections and antimicrobial susceptibility pattern over a nine-year period at St. Dominic Hospital, Akwatia, in the Eastern Region of Ghana.

Method

This study retrospectively analysed data from 4,489 patients who were referred to the Laboratory Department for blood culture and sensitivity testing from January 2009 to December 2017. Sociodemographic data included age, gender, and patients' department. Blood culture results were retrieved from archival records in the laboratory. The authorities of St. Dominic Hospital granted approval for the study.

Results

The incidence of bloodstream infection over the 9 years was 51.4 positive cultures per 100,000 hospital attendance. Staphylococcus aureus was the leading causative agent of bacteraemia for the first two scalar years (2009–2011 (38.9%) and 2012–2014 (42.2%)) while coagulase-negative staphylococcus (CoNS) (50.5%) was predominant for the last scalar year (2015–2017), followed by Staphylococcus aureus (169/587 (28.8%)). The highest incidence of bloodstream infections was recorded in the wet seasons (months of May (8.9 per 10,000 persons) and October (10.1 per 10,000 persons)). The bacterial isolates demonstrated high resistance to tetracyclines (390/531 (73.4%)), penicillins (1282/1669 (76.8%)), and sulphonamides (450/499 (90.2%)).

Conclusion

Bloodstream infection and antimicrobial resistance are high in patients seeking healthcare in Akwatia. This therefore calls for concerted efforts aimed at reducing the incidence in the study area.

A Phase 1 Study of Intravenous Plazomicin in Healthy Adults to Assess Potential Effects on the QT/QTc Interval, Safety, and Pharmacokinetics

Plazomicin is an aminoglycoside with in vitro activity against multidrug-resistant Enterobacteriaceae. A phase 1, randomized, double-blind, crossover study assessed the potential effects of plazomicin on cardiac repolarization (NCT01514929). Fifty-six healthy adults (24 men, 32 women) received a single therapeutic dose of plazomicin (15 mg/kg administered by 30-minute intravenous infusion), a single supratherapeutic dose of plazomicin (20 mg/kg administered by 30-minute intravenous infusion), placebo, or oral moxifloxacin (400 mg). The primary end point was the baseline-adjusted, placebo-corrected QTc interval using the Fridericia formula (ΔΔQTcF). Assay sensitivity was concluded if the lower limit of a 1-sided 95%CI (adjusted for multiplicity using the Hochberg procedure) for moxifloxacin ΔΔQTcF was >5 milliseconds at ≥1 prespecified time points. No QT prolongation effect for plazomicin was concluded if the largest mean effect was <5 milliseconds, and the upper limit of a 2-sided 90%CI for plazomicin ΔΔQTcF was <10 milliseconds at all time points. Assay sensitivity was demonstrated based on moxifloxacin ΔΔQTcF. No QT prolongation effect for plazomicin was concluded because the largest mean ΔΔQTcF for plazomicin was 3.5 milliseconds, and the highest upper limit was 5.6 milliseconds. No clinically relevant changes were observed in electrocardiograms. For the 15- and 20-mg/kg dose levels of plazomicin, mean peak plasma concentration values were 76.0 and 96.6 mg/L, and mean values of the area under the concentration-time curve over 24 hours were 263 and 327 mg·h/L, respectively. Model-derived pharmacokinetic parameters and safety findings were generally consistent with previously reported plazomicin studies. In conclusion, therapeutic and supratherapeutic doses of plazomicin had no clinically significant effect on cardiac repolarization and were generally well tolerated.