Clinical utility of procalcitonin in implementation of procalcitonin-guided antibiotic stewardship in the South-East Asia and India: evidence and consensus-based recommendations

INTRODUCTION

The South-East Asian (SEA) region and India are highly susceptible to antibiotic resistance, which is caused due to lack of antimicrobial stewardship (AMS) knowledge, uncontrolled use of antibiotics, and poor infection control. Nonadherence to national/local guidelines, developed to combat antimicrobial resistance, is a major concern. A virtual advisory board was conducted to understand the current AMS standards and challenges in its implementation in these regions.

AREAS COVERED

Procalcitonin (PCT)-guided antibiotic use was discussed in various clinical conditions across initiation, management, and discontinuation stages. Most experts strongly recommended using PCT-driven antibiotic therapy among patients with lower respiratory tract infections, sepsis, and COVID-19. However, additional research is required to understand the optimal use of PCT in patients with organ transplantation and cancer patients with febrile neutropenia. Implementation of the solutions discussed in this review can help improve PCT utilization in guiding AMS in these regions and reducing challenges.

EXPERT OPINION

Experts strongly support the inclusion of PCT in AMS. They believe that PCT in combination with other clinical data to guide antibiotic therapy may result in more personalized and precise targeted antibiotic treatment. The future of PCT in antibiotic treatment is promising and may result in effective utilization of this biomarker.

In Vitro Susceptibility to Ceftazidime-Avibactam and Comparator Antimicrobial Agents of Carbapenem-Resistant Enterobacterales Isolates

The emergence of carbapenem-resistant Enterobacterales (CRE) has been recognized as a significant concern globally. Ceftazidime/avibactam (CZA) is a novel β-lactam/β-lactamase inhibitor that has demonstrated activity against isolates producing class A, C, and D β-lactamases. Here-in, we evaluated the in vitro activity of CZA and comparator antimicrobial agents against 858 CRE isolates, arising from the Southeast Asian region, collected from a large tertiary hospital in Singapore. These CRE isolates mainly comprised Klebsiella pneumoniae (50.5%), Escherichia coli (29.4%), and Enterobacter cloacae complex (17.1%). Susceptibility rates to levofloxacin, imipenem, meropenem, doripenem, aztreonam, piperacillin/tazobactam, cefepime, tigecycline, and polymyxin B were low. CZA was the most active β-lactam agent against 68.9% of the studied isolates, while amikacin was the most active agent among all comparator antibiotics (80% susceptibility). More than half of the studied isolates (51.4%) identified were Klebsiella pneumoniae carbapenemase (KPC)-2 producers, 25.9% were New Delhi metallo-β-lactamase (NDM) producers, and Oxacillinase (OXA)-48-like producers made up 10.7%. CZA was the most active β-lactam agent against KPC-2, OXA-48-like, and Imipenemase (IMI) producers (99.3% susceptible; MIC50/90: ≤1/2 mg/L). CZA had excellent activity against the non-carbapenemase-producing CRE (91.4% susceptible; MIC50/90: ≤1/8 mg/L). Expectedly, CZA had no activity against the metallo-β-lactamases (MBL)-producing CRE (NDM- and Imipenemase MBL (IMP) producers; 27.2% isolates), and the carbapenemase co-producing CRE (NDM + KPC, NDM + OXA-48-like, NDM + IMP; 3.0% isolates). CZA is a promising addition to our limited armamentarium against CRE infections, given the reasonably high susceptibility rates against these CRE isolates. Careful stewardship and rational dosing regimens are required to preserve CZA's utility against CRE infections.

Antibiotic utilisation and resistance over the first decade of nationally funded antimicrobial stewardship programmes in Singapore acute-care hospitals

OBJECTIVE

The aim of this study was to describe the time series of broad-spectrum antibiotic utilisation and incidence of antibiotic-resistant organisms during the implementation of antimicrobial stewardship programmes (ASP) in Singapore.

METHODS

An observational study was conducted using data from 2011 to 2020 in seven acute-care public hospitals. We applied joinpoint regressions to investigate changes in antibiotic utilisation rate and incidence density of antibiotic-resistant organisms.

RESULTS

Across the seven hospitals, quarterly broad-spectrum antibiotic utilisation rate remained stable. Half-yearly incidence density of antibiotic-resistant organisms with two joinpoints at first half (H1) of 2012 and second half (H2) of 2014 decreased significantly in the second and third period with a half-yearly percentage change (HPC) of -2.9% and - 0.5%, respectively. Across the five hospitals with complete data, half-yearly broad-spectrum antibiotic utilisation rate with one joinpoint decreased significantly from H1 of 2011 to H2 of 2018 (HPC - 4.0%) and H2 of 2018 to H2 2020 (HPC - 0.5%). Incidence density of antibiotic-resistant organisms decreased significantly in the two joinpoint periods from H1 of 2012 to H2 of 2014 (HPC - 2.7%) and H2 of 2014 to H2 of 2020 (HPC - 1.0%). Ceftriaxone with one joinpoint decreased significantly from H1 of 2011 to H1 of 2014 (HPC - 6.0%) and H1 of 2014 to H2 of 2020 (HPC - 1.8%) and ceftriaxone-resistant E. coli and K. pneumoniae decreased significantly in later periods, from H2 of 2016 to H2 of 2020 (HPC - 2.5%) and H1 of 2012 to H2 of 2015 (HPC - 4.6%) respectively. Anti-pseudomonal antibiotics with one joinpoint decreased significantly from H1 of 2011 to H2 of 2014 (HPC - 4.5%) and H2 of 2014 to H2 of 2020 (HPC - 0.8%) and that of quinolones with one joinpoint at H1 of 2015 decreased significantly in the first period. C. difficile with one joinpoint increased significantly from H1 of 2011 to H1 of 2015 (HPC 3.9%) and decreased significantly from H1 of 2015 to H2 of 2020 (HPC - 4.9%).

CONCLUSIONS

In the five hospitals with complete data, decrease in broad-spectrum antibiotic utilisation rate was followed by decrease in incidence density of antibiotic-resistant organisms. ASP should continue to be nationally funded as a key measure to combat antimicrobial resistance in acute care hospitals.

ACORN (A Clinically-Oriented Antimicrobial Resistance Surveillance Network) II: protocol for case based antimicrobial resistance surveillance

Background: Antimicrobial resistance surveillance is essential for empiric antibiotic prescribing, infection prevention and control policies and to drive novel antibiotic discovery. However, most existing surveillance systems are isolate-based without supporting patient-based clinical data, and not widely implemented especially in low- and middle-income countries (LMICs). Methods: A Clinically-Oriented Antimicrobial Resistance Surveillance Network (ACORN) II is a large-scale multicentre protocol which builds on the WHO Global Antimicrobial Resistance and Use Surveillance System to estimate syndromic and pathogen outcomes along with associated health economic costs. ACORN-healthcare associated infection (ACORN-HAI) is an extension study which focuses on healthcare-associated bloodstream infections and ventilator-associated pneumonia. Our main aim is to implement an efficient clinically-oriented antimicrobial resistance surveillance system, which can be incorporated as part of routine workflow in hospitals in LMICs. These surveillance systems include hospitalised patients of any age with clinically compatible acute community-acquired or healthcare-associated bacterial infection syndromes, and who were prescribed parenteral antibiotics. Diagnostic stewardship activities will be implemented to optimise microbiology culture specimen collection practices. Basic patient characteristics, clinician diagnosis, empiric treatment, infection severity and risk factors for HAI are recorded on enrolment and during 28-day follow-up. An R Shiny application can be used offline and online for merging clinical and microbiology data, and generating collated reports to inform local antibiotic stewardship and infection control policies. Discussion: ACORN II is a comprehensive antimicrobial resistance surveillance activity which advocates pragmatic implementation and prioritises improving local diagnostic and antibiotic prescribing practices through patient-centred data collection. These data can be rapidly communicated to local physicians and infection prevention and control teams. Relative ease of data collection promotes sustainability and maximises participation and scalability. With ACORN-HAI as an example, ACORN II has the capacity to accommodate extensions to investigate further specific questions of interest.

Comparative Activities of Novel Therapeutic Agents against Molecularly Characterized Clinical Carbapenem-Resistant Enterobacterales Isolates

Limited treatment options exist for the treatment of carbapenem-resistant Enterobacterales (CRE) bacteria. Fortunately, there are several recently approved antibiotics indicated for CRE infections. Here, we examine the in vitro activity of various novel agents (eravacycline, plazomicin, ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam) and comparators (tigecycline, amikacin, levofloxacin, fosfomycin, polymyxin B) against 365 well-characterized CRE clinical isolates with various genotypes. Nonduplicate isolates collected from the largest public health hospital in Singapore between 2007 and 2020 were subjected to antimicrobial susceptibility testing (broth microdilution or antibiotic gradient test strips). Susceptibilities were defined using Clinical and Laboratory Standards Institute (CLSI) or Food and Drug Administration (FDA) interpretative criteria. Sequence types and resistance mechanisms were characterized using short-read whole-genome sequencing. Overall, tigecycline and plazomicin exhibited the highest susceptibility rates (89.6% and 80.8%, respectively). However, the tigecycline susceptibility breakpoint utilized here may be outdated in view of prevailing pharmacokinetic-pharmacodynamic (PK/PD) data. Susceptibility varied by carbapenemase genotype; the β-lactam/β-lactamase inhibitor combinations were equally active (92.3 to 99.2% susceptible) against KPC producers, but only ceftazidime-avibactam retained high susceptibility (98.7%) against OXA-48-like producers. Against metallo-β-lactamase producers, only plazomicin exhibited moderate activity (77.0% susceptible). Aminoglycoside activity was also influenced by carbapenemase genotypes. This work provides an insight into the comparative activity and presumptive utility of novel agents in this geographic region. IMPORTANCE This study determined the susceptibilities of carbapenem-resistant Enterobacterales isolates to various novel antimicrobial agents (ceftazidime-avibactam, imipenem-relebactam, meropenem-vaborbactam, eravacycline, and plazomicin). Whole-genome sequencing was performed for all strains. Our study findings provide insights into the comparative activities of novel agents in this geographic region. Plazomicin and ceftazidime-avibactam exhibited the lowest nonsusceptibility rates and may be considered promising agents in the management of carbapenem-resistant Enterobacterales infections. We note also that antibiotic activity is influenced by genotypes and that understanding the geographic region's molecular epidemiology could aid in the definition of the presumptive utility of novel agents and contribute to antibiotic decision-making.

Genomic Surveillance of Carbapenem-Resistant Klebsiella pneumoniae from a Major Public Health Hospital in Singapore

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a global public health threat. In this study, we employed whole-genome sequencing (WGS) to determine the genomic epidemiology of a longitudinal collection of clinical CRKP isolates recovered from a large public acute care hospital in Singapore. Phylogenetic analyses, a characterization of resistance and virulence determinants, and plasmid profiling were performed for 575 unique CRKP isolates collected between 2009 and 2020. The phylogenetic analyses identified the presence of global high-risk clones among the CRKP population (clonal group [CG] 14/15, CG17/20, CG147, CG258, and sequence type [ST] 231), and these clones constituted 50% of the isolates. Carbapenemase production was common (n = 497, 86.4%), and KPC was the predominant carbapenemase (n = 235, 40.9%), followed by OXA-48-like (n = 128, 22.3%) and NDM (n = 93, 16.2%). Hypervirulence was detected in 59 (10.3%) isolates and was most common in the ST231 carbapenemase-producing isolates (21/59, 35.6%). Carbapenemase genes were associated with diverse plasmid replicons; however, there was an association of blaOXA-181/232 with ColKP3 plasmids. This study presents the complex and diverse epidemiology of the CRKP strains circulating in Singapore. Our study highlights the utility of WGS-based genomic surveillance in tracking the population dynamics of CRKP. IMPORTANCE In this study, we characterized carbapenem-resistant Klebsiella pneumoniae clinical isolates collected over a 12-year period in the largest public acute-care hospital in Singapore using whole-genome sequencing. The results of this study demonstrate significant genomic diversity with the presence of well-known epidemic, multidrug-resistant clones amid a diverse pool of nonepidemic lineages. Genomic surveillance involving comprehensive resistance, virulence, and plasmid gene content profiling provided critical information for antimicrobial resistance monitoring and highlighted future surveillance priorities, such as the emergence of ST231 K. pneumoniae strains bearing multidrug resistance, virulence elements, and the potential plasmid-mediated transmission of the blaOXA-48-like gene. The findings here also reinforce the necessity of unique infection control and prevention strategies that take the genomic diversity of local circulating strains into consideration.

inPhocus: Current State and Challenges of Phage Research in Singapore

Bacteriophages and phage-derived proteins are a promising class of antibacterial agents that experience a growing worldwide interest. To map ongoing phage research in Singapore and neighboring countries, Lee Kong Chian School of Medicine, Nanyang Technological University Singapore (NTU) and Yong Loo Lin School of Medicine, National University of Singapore (NUS) recently co-organized a virtual symposium on Bacteriophage and Bacteriophage-Derived Technologies, which was attended by more than 80 participants. Topics were discussed relating to phage life cycles, diversity, the roles of phages in biofilms and the human gut microbiome, engineered phage lysins to combat polymicrobial infections in wounds, and the challenges and prospects of clinical phage therapy. This perspective summarizes major points discussed during the symposium and new perceptions that emerged after the panel discussion.

Quantification of Fosfomycin in Combination with Nine Antibiotics in Human Plasma and Cation-Adjusted Mueller-Hinton II Broth via LCMS

Fosfomycin-based combination therapy has emerged as an attractive option in our armamentarium due to its synergistic activity against carbapenem-resistant Gram-negative bacteria (CRGNB). The ability to simultaneously measure fosfomycin and other antibiotic drug levels will support in vitro and clinical investigations to develop rational antibiotic combination dosing regimens against CRGNB infections. We developed an analytical assay to measure fosfomycin with nine important antibiotics in human plasma and cation-adjusted Mueller–Hinton II broth (CAMHB). We employed a liquid-chromatography tandem mass spectrometry method and validated the method based on accuracy, precision, matrix effect, limit-of-detection, limit-of-quantification, specificity, carryover, and short-term and long-term stability on U.S. Food & Drug Administration (FDA) guidelines. Assay feasibility was assessed in a pilot clinical study in four patients on antibiotic combination therapy. Simultaneous quantification of fosfomycin, levofloxacin, meropenem, doripenem, aztreonam, piperacillin/tazobactam, ceftolozane/tazobactam, ceftazidime/avibactam, cefepime, and tigecycline in plasma and CAMHB were achieved within 4.5 min. Precision, accuracy, specificity, and carryover were within FDA guidelines. Fosfomycin combined with any of the nine antibiotics were stable in plasma and CAMHB up to 4 weeks at −80 °C. The assay identified and quantified the respective antibiotics administered in the four subjects. Our assay can be a valuable tool for in vitro and clinical applications.

In vitro Bactericidal Activities of Combination Antibiotic Therapies Against Carbapenem-Resistant Klebsiella pneumoniae With Different Carbapenemases and Sequence Types

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is becoming increasingly problematic due to the limited effectiveness of new antimicrobials or other factors such as treatment cost. Thus, combination therapy remains a suitable treatment option. We aimed to evaluate the in vitro bactericidal activity of various antibiotic combinations against CRKP with different carbapenemase genotypes and sequence types (STs). Thirty-seven CRKP with various STs and carbapenemases were exposed to 11 antibiotic combinations (polymyxin B or tigecycline in combination with β-lactams including aztreonam, cefepime, piperacillin/tazobactam, doripenem, meropenem, and polymyxin B with tigecycline) in static time-kill studies (TKS) using clinically achievable concentrations. Out of the 407 isolate-combination pairs, only 146 (35.8%) were bactericidal (≥3 log₁₀CFU/mL decrease from initial inoculum). Polymyxin B in combination with doripenem, meropenem, or cefepime was the most active, each demonstrating bactericidal activity in 27, 24, and 24 out of 37 isolates, respectively. Tigecycline in combination with β-lactams was rarely bactericidal. Aside from the lower frequency of bactericidal activity in the dual-carbapenemase producers, there was no apparent difference in combination activity among the strains with other carbapenemase types. In addition, bactericidal combinations were varied even in strains with similar STs, carbapenemases, and other genomic characteristics. Our findings demonstrate that the bactericidal activity of antibiotic combinations is highly strain-specific likely owing to the complex interplay of carbapenem-resistance mechanisms, i.e., carbapenemase genotype alone cannot predict in vitro bactericidal activity. The availability of WGS information can help rationalize the activity of certain combinations. Further studies should explore the use of genomic markers with phenotypic information to predict combination activity.

Utility and applicability of rapid diagnostic testing in antimicrobial stewardship in Asia Pacific: A Delphi consensus

Rapid diagnostic tests (RDTs) facilitate fast and accurate identification of infectious disease microorganisms and are a valuable component of multimodal antimicrobial stewardship (AMS) programs but are currently underutilized in the Asia-Pacific region. An experienced group of infectious diseases clinicians, clinical microbiologists, and a clinical pharmacist used a modified Delphi consensus approach to construct 10 statements, aiming to optimize the utility and applicability of infection-related RDTs for AMS in the Asia-Pacific region. They provide guidance on definition, types, optimal deployment, measuring effectiveness, and overcoming key challenges. The Grading of Recommendations Assessment, Development, and Evaluation system was applied to indicate the strength of the recommendation and the quality of the underlying evidence. Given the diversity of the Asia-Pacific region, the trajectory of RDT development will vary widely; the collection of local data should be prioritized to allow realization and optimization of the full benefits of RDTs in AMS.

Genomic characterization of carbapenem-non-susceptible Pseudomonas aeruginosa in Singapore

Pseudomonas aeruginosa is a clinically important pathogen implicated in many hospital-acquired infections. Its propensity to acquire broad-spectrum resistance has earned the organism its status as a severe public health threat requiring urgent control measures. While whole-genome sequencing-based genomic surveillance provides a means to track antimicrobial resistance, its use in molecular epidemiological surveys of P. aeruginosa remains limited, especially in the Southeast Asian region. We sequenced the whole genomes of 222 carbapenem-non-susceptible P. aeruginosa (CNPA) isolates collected in 2006–2020 at the largest public acute care hospital in Singapore. Antimicrobial susceptibilities were determined using broth microdilution. Clonal relatedness, multi-locus sequence types, and antimicrobial resistance determinants (acquired and chromosomal) were determined. In this study, CNPA exhibited broad-spectrum resistance (87.8% multi-drug resistance), retaining susceptibility only to polymyxin B (95.0%) and amikacin (55.0%). Carbapenemases were detected in 51.4% of the isolates, where IMP and NDM metallo-β-lactamases were the most frequent. Carbapenem resistance was also likely associated with OprD alterations or efflux mechanisms (ArmZ/NalD mutations), which occurred in strains with or without carbapenemases. The population of CNPA in the hospital was diverse; the 222 isolates grouped into 68 sequence types (ST), which included various high-risk clones. We detected an emerging clone, the NDM-1-producing ST308, in addition to the global high-risk ST235 clone which was the predominant clone in our population. Our results thus provide a “snapshot” of the circulating lineages of CNPA locally and the prevailing genetic mechanisms contributing to carbapenem resistance. This database also serves as the baseline for future prospective surveillance studies.

Antibiotic stewardship program (ASP) in palliative care: antibiotics, to give or not to give

Antimicrobial therapy in terminally ill patients remains controversial as goals of care tend to be focused on optimizing comfort. International guidelines recommend for antibiotic stewardship program (ASP) involvement in antibiotic decisions in palliative patients. The primary objective was to evaluate the clinical impact of ASP interventions made to stop broad-spectrum intravenous antibiotics in terminally ill patients. This was a retrospective chart review of 459 terminally ill patients in Singapore General Hospital audited by ASP between December 2010 and December 2018. Antibiotic duration, time-to-terminal discharge for end-of-life care, time-to-mortality, and mortality rates of patients with antibiotics ceased or continued upon ASP recommendations were compared. A total of 283 and 176 antibiotic courses were ceased and continued post-intervention, respectively. The intervention acceptance rate was 61.7%. The 7-day mortality rate (47.3% vs 61.9%, p = 0.003) was lower in the ceased group, while 30-day mortality rate (76.0% vs 81.2%, p = 0.203) and time-to-mortality post-intervention (3 [0-24] vs 2 [0-27] days, p = 0.066) did not differ between the ceased and continued groups. After excluding the 57 patients who had antibiotics continued until death within 48 h of intervention, only time-to-mortality post-intervention was statistically significantly shorter in the ceased group (3 [0-24] vs 4 [0-27], p < 0.001). Of the 131 terminally discharged patients, antibiotic duration (4 [0-17] vs 6.5 [1-14] days, p = 0.001) and time-to-terminal discharge post-intervention (6 [0-74] vs 10.5 [3-63] days, p = 0.001) were shorter in the ceased group. Antibiotic cessation in terminally ill patients was safe, and was associated with a significantly shorter time-to-terminal discharge.

Discontinuation of Antibiotics in Patients with Neurological Conditions - A Study on the Impact of an Antimicrobial Stewardship Program (ASP) in a Tertiary Institution

BACKGROUND

Up to 50% of antibiotics are prescribed either unnecessarily or inappropriately in most hospitals worldwide. In the largest tertiary hospital in Singapore, patients with neurological conditions were often initiated on antibiotics for change in mental state or isolated fevers. We hypothesize that Antimicrobial Stewardship Program (ASP) interventions to discontinue empirical antibiotics in neurological patients with no clinical evidence of bacterial infection are safe. The aim of this study was to compare clinical impact and safety outcomes of ASP interventions between accepted and rejected groups.

METHODS

A retrospective review of the ASP database was conducted for all patients admitted to the neurology department in Singapore General Hospital between January 2014 and December 2017. Interventions were followed up and patients were classified into two intervention groups, the accepted and rejected groups. Demographic data, age-adjusted Charlson co-morbidity index, duration of antibiotic therapy, length of hospital stay post-ASP intervention (PLOS), infection-related readmissions and mortality were compared between the two groups. Data were expressed as mean ± standard deviation for continuous variables, and unpaired Student's t-test was performed to determine intergroup differences between mean values.

RESULTS

The ASP team recommended 184 interventions, with an overall acceptance rate of 82.6% (152/184). There was no significant difference in demographics and age-adjusted Charlson co-morbidity index between the two groups. The accepted group had a shorter duration of therapy by 1.67 days (4.99±2.50 days vs. 6.66±2.34 days; P<0.01) and a shorter PLOS by 2 days, although this was not statistically significant (22.5±22.2 days vs. 24.5±51.4 days; P=0.83). There were no significant differences between the two groups in 14-day mortality and readmission rates.

CONCLUSION

In neurological patients with no clinical evidence of bacterial infections, ASP interventions to discontinue empirical antibiotics were not associated with increased mortality and readmissions but were associated with significant reduction in duration of therapy.

In vitro Pharmacodynamics and PK/PD in Animals

In the last decade, considerable advancements have been made to identify the pharmacokinetic/pharmacodynamic (PK/PD) index that defines the antimicrobial activity of polymyxins. Dose-fractionation studies performed in hollow-fiber models found that altering the dosing schedule had little impact on the killing or suppression of resistance emergence, alluding to AUC/MIC as the pharmacodynamic index that best describes polymyxin's activity. For in vivo efficacy, the PK/PD index that was the most predictive of the antibacterial effect of colistin against P. aeruginosa and A. baumannii was ƒAUC/MIC.

Ten-year narrative review on antimicrobial resistance in Singapore

Antimicrobial resistance (AMR) results in drug-resistant infections that are harder to treat, subsequently leading to increased morbidity and mortality. In 2008, we reviewed the problem of AMR in Singapore, limiting our discussion to the human healthcare sector. Ten years later, we revisit this issue again, reviewing current efforts to contain it in order to understand the progress made as well as current and emerging challenges. Although a significant amount of work has been done to control AMR and improve antibiotic prescribing in Singapore, most of it has focused on the hospital setting, with mixed impact. The role of antibiotic use and AMR in food animals and the environment - and the link to human health - is better understood today. This issue of AMR encompasses both human health as well as animal/food safety, and efforts to control it will need to continually evolve to maintain or improve on current gains.

Risk factors and outcomes associated with the isolation of polymyxin B and carbapenem-resistant Enterobacteriaceae spp.: A case-control study

Increasing resistance to polymyxin, a last-line antibiotic, is a growing public health concern worldwide. The primary objective of this study was to identify predictors for the isolation of polymyxin-resistant (PR) carbapenem-resistant Enterobacteriaceae (CRE) among hospitalized patients. The secondary objective was to describe the clinical outcomes of patients with PR-CRE infections. A retrospective case-control study including patients admitted to Singapore General Hospital between June 2012 and June 2016 was conducted. Cases were defined as patients who had clinical cultures from which a PR-CRE was isolated. Controls were randomly selected from patients with polymyxin-susceptible (PS) CRE admitted during the same period, and frequency-matched to site of isolation. We included 37 PR cases and 111 PS controls. Polymyxin resistance was detected predominantly in Enterobacter spp. (54.1%) and Klebsiella pneumoniae (43.2%). Multilocus sequence typing showed little clonal relatedness among the isolates. mcr-1 was detected in two PR-CRE isolates. Multivariable analyses showed that PR-CRE isolation was associated with prior polymyxins (adjusted odds ratio (OR), 21.31; 95% confidence interval (CI), 3.04-150.96) and carbapenem exposures (OR 3.74; CI 1.13-12.44), when adjusted for time at risk and bacteria species. In PR-CRE patients with infections, the 30-day all-cause in-hospital mortality was 50.0% as compared to 38.1% in patients with PS-CRE (P = 0.346). Prior polymyxin and carbapenem exposures were independent risk factors for isolation of PR-CRE. Outcomes of PR-CRE and PS-CRE infections were similar in this study.

Do antimicrobial stewardship programme interventions reduce the rate of and protect against Clostridium difficile infection?

OBJECTIVES

Antimicrobial stewardship programmes (ASPs) have often been recommended as a viable solution to minimise the incidence of Clostridium difficile infection (CDI), which can be life-threatening. This study aimed to evaluate whether ASP interventions have contributed to reducing CDI rates.

METHODS

A retrospective review of ASP interventions issued from January 2013 to April 2014 was performed using data from the ASP database of Singapore General Hospital, a 1600-bed tertiary-care hospital in Singapore. A total of 283 interventions satisfied the inclusion criteria, of which commonly audited antibiotics were piperacillin/tazobactam (41.3%) and carbapenems (54.8%). Comparisons were made at 30days post-intervention between those with accepted or rejected interventions. The primary outcome was CDI incidence; secondary outcomes included length of hospitalisation post-intervention, 30-day mortality and CDI recurrence rate.

RESULTS

Whilst the median duration of antibiotic therapy was reduced by 2days (6days vs. 4 days; P<0.001), acceptance of ASP interventions did not alter primary CDI incidence at 30days (P=0.644) post-intervention. However, reduced CDI recurrence rates were observed for patients positive for CDI in the accepted patient group compared with the rejected group (0% vs. 37.5%; P=0.03), with no difference in CDI 30-day mortality between the two groups.

CONCLUSION

Intervention acceptance did not contribute to a significant reduction in CDI incidence but may be associated with lower recurrence rates, although further studies are required.

Molecular mechanisms of azole resistance in Candida bloodstream isolates

BACKGROUND

Antifungal resistance rates are increasing. We investigated the mechanisms of azole resistance of Candida spp. bloodstream isolates obtained from a surveillance study conducted between 2012 and 2015.

METHODS

Twenty-six azole non-susceptible Candida spp. clinical isolates were investigated. Antifungal susceptibilities were determined using the Sensititre YeastOne® YO10 panel. The ERG11 gene was amplified and sequenced to identify amino acid polymorphisms, while real-time PCR was utilised to investigate the expression levels of ERG11, CDR1, CDR2 and MDR1.

RESULTS

Azole cross-resistance was detected in all except two isolates. Amino acid substitutions (A114S, Y257H, E266D, and V488I) were observed in all four C. albicans tested. Of the 17 C. tropicalis isolates, eight (47%) had ERG11 substitutions, of which concurrent observation of Y132F and S154F was the most common. A novel substitution (I166S) was detected in two of the five C. glabrata isolates. Expression levels of the various genes differed between the species but CDR1 and CDR2 overexpression appeared to be more prominent in C. glabrata.

CONCLUSIONS

There was interplay of various different mechanisms, including mechanisms which were not studied here, responsible for azole resistance in Candida spp in our study.

Discontinuation of antibiotic therapy within 24 hours of treatment initiation for patients with no clinical evidence of bacterial infection: a 5-year safety and outcome study from Singapore General Hospital Antimicrobial Stewardship Program

BACKGROUND

Overprescribing antibiotics for patients with no bacterial infection is of growing global concern. It is important for timely Antimicrobial Stewardship Program (ASP) intervention to discontinue antibiotics for patients whose symptoms can be explained by non-infective causes, and without availability of bacterial cultures and susceptibilities reports. This study aimed to evaluate clinical outcomes and safety of early ASP review in these patients.

METHODS

A retrospective review of the ASP database (January 2010 to December 2014) was conducted to identify patients for whom ASP recommended discontinuation of empiric antibiotics within 24 hours of prescribing. Demographics were collected. Clinical outcomes - duration of therapy, length of hospital stay (LOS), infection-related readmissions, and all-cause mortality - were compared between interventions accepted and rejected groups. Continuous data were analysed via unpaired Student's t-test. Categorical data were analysed using χ² test or Fisher's exact test, as appropriate.

RESULTS

The ASP team recommended 794 interventions (overall acceptance rate of 72.9%, 579 of 794). There were no significant between-group differences in underlying demographics, and Charlson comorbidity index score. However, the interventions acceptance group had significantly shorter duration of therapy by 2.61 days (2.72 ± 3.04 vs. 5.33 ± 2.54 days; P < 0.01) and LOS by 7.41 days (7.98 ± 13.14 vs. 15.39 ± 22.62 days; P < 0.01), with estimated cost savings of SGD10 817 per patient. There were no significant between-group differences in 14-day mortality and readmission rates.

CONCLUSION

Prompt ASP interventions at Singapore General Hospital were associated with significant reductions in duration of therapy and LOS, with cost savings. It was demonstrated that it is safe to discontinue antibiotics within 24 hours of prescribing for patients with no evidence of bacterial infections.

Optimisation of antimicrobial dosing based on pharmacokinetic and pharmacodynamic principles

While suboptimal dosing of antimicrobials has been attributed to poorer clinical outcomes, clinical cure and mortality advantages have been demonstrated when target pharmacokinetic (PK) and pharmacodynamic (PD) indices for various classes of antimicrobials were achieved to maximise antibiotic activity. Dosing optimisation requires a good knowledge of PK/PD principles. This review serves to provide a foundation in PK/PD principles for the commonly prescribed antibiotics (β-lactams, vancomycin, fluoroquinolones and aminoglycosides), as well as dosing considerations in special populations (critically ill and obese patients). PK principles determine whether an appropriate dose of antimicrobial reaches the intended pathogen(s). It involves the fundamental processes of absorption, distribution, metabolism and elimination, and is affected by the antimicrobial's physicochemical properties. Antimicrobial pharmacodynamics define the relationship between the drug concentration and its observed effect on the pathogen. The major indicator of the effect of the antibiotics is the minimum inhibitory concentration. The quantitative relationship between a PK and microbiological parameter is known as a PK/PD index, which describes the relationship between dose administered and the rate and extent of bacterial killing. Improvements in clinical outcomes have been observed when antimicrobial agents are dosed optimally to achieve their respective PK/PD targets. With the rising rates of antimicrobial resistance and a limited drug development pipeline, PK/PD concepts can foster more rational and individualised dosing regimens, improving outcomes while simultaneously limiting the toxicity of antimicrobials.

Importance of control groups when delineating antibiotic use as a risk factor for carbapenem resistance, extreme-drug resistance, and pan-drug resistance in Acinetobacter baumannii and Pseudomonas aeruginosa: A systematic review and meta-analysis

BACKGROUND

Carbapenem-resistant (CR), extremely drug-resistant (XDR), and pan-drug-resistant (PDR) Acinetobacter baumannii and Pseudomonas aeruginosa pose a huge clinical threat. This study reviews the impact of control groups on the association of antecedent antibiotic use and the acquisition of CR/XDR/PDR A. baumannii and P. aeruginosa.

METHODS

Studies investigating the role of antibiotics as a risk factor for CR/XDR/PDR A. baumannii and P. aeruginosa acquisition in adult hospitalized patients from 1950 to 2016 were identified in the databases. These were divided into two groups: antibiotic-resistant versus antibiotic-sensitive pathogens (group I); antibiotic-resistant versus no infection (group II). A random-effects model was performed.

RESULTS

Eighty-five studies (46 A. baumannii, 38 P. aeruginosa, and one of both) involving 22 396 patients were included. CR was investigated in 60 studies, XDR in 20 studies, and PDR in two studies. Prior antibiotic exposure was associated with significant acquisition of CR/XDR/PDR A. baumannii and P. aeruginosa in both groups I and II (p<0.05). Antibiotic classes implicated in both groups included aminoglycosides, carbapenems, glycopeptides, and penicillins. Cephalosporin use was not associated with resistance in either group. Fluoroquinolone exposure was only associated with resistance in group I but not group II.

CONCLUSIONS

Control groups play an important role in determining the magnitudes of risk estimates for risk factor studies, hence careful selection is necessary. Antibiotic exposure increases the acquisition of highly resistant A. baumannii and P. aeruginosa, thus appropriate antibiotic use is imperative.

Candidemia in a major regional tertiary referral hospital - epidemiology, practice patterns and outcomes

Background

Candidemia is a common cause of nosocomial bloodstream infections, resulting in high morbidity and mortality. This study was conducted to describe the epidemiology, species distribution, antifungal susceptibility patterns and outcomes of candidemia in a large regional tertiary referral hospital.

Methods

A retrospective surveillance study of patients with candidemia was conducted at Singapore General Hospital between July 2012 and December 2015. In addition, incidence densities and species distribution of candidemia episodes were analysed from 2008 to 2015.

Results

In the period of 2012 to 2015, 261 candidemia episodes were identified. The overall incidence was 0.14/1000 inpatient-days. C. glabrata (31.4%), C. tropicalis (29.9%), and C. albicans (23.8%) were most commonly isolated. The incidence of C. glabrata significantly increased from 2008 to 2015 (Coefficient 0.004, confidence interval 0–0.007, p = 0.04). Fluconazole resistance was detected primarily in C. tropicalis (16.7%) and C. glabrata (7.2%). fks mutations were identified in one C. albicans and one C. tropicalis. Candidemia episodes caused by C. tropicalis were more commonly encountered in patients with haematological malignancies (p = 0.01), neutropenia (p < 0.001) and higher SAPS II scores (p = 0.02), while prior exposure to echinocandins was associated with isolation of C. parapsilosis (p = 0.001). Echinocandins (73.3%) were most commonly prescribed as initial treatment. The median (range) time to initial treatment was 1 (0–9) days. The 30-day in-hospital mortality rate was 49.8%. High SAPS II score (Odds ratio, OR 1.08; 95% confidence interval, CI 1.05–1.11) and renal replacement therapy (OR 5.54; CI 2.80–10.97) were independent predictors of mortality, while drain placement (OR 0.44; CI 0.19–0.99) was protective.

Conclusions

Decreasing azole susceptibilities to C. tropicalis and the emergence of echinocandin resistance suggest that susceptibility patterns may no longer be sufficiently predicted by speciation in our institution. Candidemia is associated with poor outcomes. Strategies optimising antifungal therapy, especially in the critically-ill population, should be explored.

Carbapenem Resistance in Gram-Negative Bacteria: The Not-So-Little Problem in the Little Red Dot

Singapore is an international travel and medical hub and faces a genuine threat for import and dissemination of bacteria with broad-spectrum resistance. In this review, we described the current landscape and management of carbapenem resistance in Gram-negative bacteria (GNB) in Singapore. Notably, the number of carbapenem-resistant Enterobacteriaceae has exponentially increased in the past two years. Resistance is largely mediated by a variety of mechanisms. Polymyxin resistance has also emerged. Interestingly, two Escherichia coli isolates with plasmid-mediated mcr-1 genes have been detected. Evidently, surveillance and infection control becomes critical in the local setting where resistance is commonly related to plasmid-mediated mechanisms, such as carbapenemases. Combination antibiotic therapy has been proposed as a last-resort strategy in the treatment of extensively drug-resistant (XDR) GNB infections, and is widely adopted in Singapore. The diversity of carbapenemases encountered, however, presents complexities in both carbapenemase detection and the selection of optimal antibiotic combinations. One unique strategy introduced in Singapore is a prospective in vitro combination testing service, which aids physicians in the selection of individualized combinations. The outcome of this treatment strategy has been promising. Unlike countries with a predominant carbapenemase type, Singapore has to adopt management strategies which accounts for diversity in resistance mechanisms.

Impact of Antimicrobial Stewardship Program (ASP) on Outcomes in Patients with Acute Bacterial Skin and Skin Structure Infections (ABSSSIs) in an Acute-Tertiary Care Hospital

INTRODUCTION

Acute bacterial skin and skin structure infections (ABSSSIs) are among the most common infections treated in hospitals, but to date, there has been little information with regards to the implementation of Antimicrobial Stewardship Programs (ASPs) for patients with ABSSSIs. Hence, we aim to evaluate the impact of ASPs on the following outcomes in patients with ABSSSIs: duration of therapy and hospital stay, 14-day reinfection, infection-related readmissions and mortality.

METHODS

A retrospective review of the ASP database was conducted, focusing on selected outcomes (as above) among all patients in whom the institution's ASP recommended a change in antibiotic regimen-de-escalation of the antibiotic based on culture results; discontinuation of the antibiotic; narrowing of the empirical coverage; and intravenous-to-oral (i.v.-to-p.o.) switch between September 2009 and December 2012. Data were expressed as mean ± standard deviation for continuous variables, and unpaired Student's t test was performed to determine intergroup differences between mean values. For categorical variables, data were presented as number and percentage and analyzed using the χ (2) test or Fisher's exact test, as appropriate.

RESULTS

ASP recommended 407 interventions with an overall acceptance rate of 66.8%. ASP interventions significantly reduced median duration of therapy by 2 [from a median (interquartile range, IQR) of 8 (6-12) days to 6 (4-9) days] and median length of stay by 5 days [from median (IQR) of 12 (5-32) days to 7 (3-18) days]. This led to an estimated total cost avoidance of USD 0.7 million. There were no significant differences in the 14-day reinfection, infection-related readmission and mortality rates between patients whose physicians accepted and those who rejected ASP interventions.

CONCLUSION

Interventions recommended by the ASP in Singapore General Hospital were safe and associated with a significant reduction in duration of therapy and hospital stay. The results of our study have affirmed the role of ASP in optimizing the care of patients with ABSSSI.

Candida Surveillance in Surgical Intensive Care Unit (SICU) in a Tertiary Institution

Background

Colonization of patients occurs before development into invasive candidiasis. There is a need to determine the incidences of Candida colonization and infection in SICU patients, and evaluate the usefulness of beta-D-glucan (BDG) assay in diagnosing invasive candidiasis when patients are colonized.

Methods

Clinical data and fungal surveillance cultures in 28 patients were recorded from November 2010, and January to February 2011. Susceptibilities of Candida isolates to fluconazole, voriconazole, amphotericin B, micafungin, caspofungin and anidulafungin were tested via Etest. The utilities of BDG, Candida score and colonization index for candidiasis diagnosis were compared via ROC.

Results

30 BDG assays were performed in 28 patients. Four assay cases had concurrent colonization and infection; 23 had concurrent colonization and no infection; three had no concurrent colonization and infection. Of 136 surveillance swabs, 52 (38.24 %) were positive for Candida spp, with C. albicans being the commonest. Azole resistance was detected in C. albicans (7 %). C. glabrata and C. tropicalis were, respectively, 100 and 7 % SDD to fluconazole. All 3 tests showed high sensitivity of 75–100 % but poor specificity ranging 15.38–38.46 %. BDG performed the best (AUC of 0.89).

Conclusions

Despite that positive BDG is common in surgical patients with Candida spp colonization, BDG performed the best when compared to CI and CS.

Role of antibiotic prophylaxis in necrotizing pancreatitis: a meta-analysis

Several studies have yielded conflicting results on the role of antibiotic prophylaxis in improving outcomes in acute necrotizing pancreatitis. A meta-analysis was carried out to investigate the impact of antibiotic prophylaxis in the incidence of infected pancreatic necrosis and mortality.

METHODOLOGY

Randomized controlled trials and cohort studies investigating impact of prophylactic systemic antibiotic used in acute necrotizing pancreatitis were retrieved from online databases. An overall analysis was done with all studies (Group 1), followed by subgroup analyses with randomized controlled trials (Group 2) and cohort studies (Group 3). Risk ratios (RR) were calculated for the impact of antibiotic prophylaxis in the incidence of infected pancreatic necrosis and mortality in each group using random effects model.

RESULTS

Eleven studies involving 864 patients were included. No significant differences in the incidence of infected pancreatic necrosis were observed with prophylactic antibiotic use in all groups. Prophylactic antibiotic use was not associated with significant differences in all-cause mortality in Group 2 (RR = 0.75; p = 0.24) but was associated with a reduction in Groups 1 (RR = 0.66, p = 0.02) and 3 (RR = 0.55, p = 0.04). There was no statistical difference in the incidence of fungal infections and surgical interventions.

CONCLUSION

Antibiotic prophylaxis does not significantly reduce the incidence of infected pancreatic necrosis but may affect all-cause mortality in acute necrotizing pancreatitis.

Prospective audit and feedback in antimicrobial stewardship: is there value in early reviewing within 48 h of antibiotic prescription?

Antimicrobial stewardship programme (ASP) methodologies are not well defined, with most preferring to wait ≥72-96 h following antibiotic prescription before reviewing patients. However, we hypothesise that early ASP reviews and interventions are beneficial and do not adversely impact patient safety. This study aimed to evaluate the impact of early ASP interventions within 48 h of antibiotic prescription on patient outcomes and safety. A prospective review of ASP interventions made within 48 h of antibiotic prescription in Singapore General Hospital (SGH) from January to December 2012 was conducted. Patient demographics and outcomes were extracted from the database maintained by the ASP team. For culture-directed treatment, there was a shorter mean duration of therapy (DOT) in the accepted group compared with the rejected group (2.26 days vs. 5.56 days; P<0.001). ASP interventions did not alter the length of hospital stay (LOS), 30-day mortality, 14-day Clostridium difficile infection (CDI), 30-day re-admissions and 14-day re-infection (all P>0.05). For empirical treatment, a shorter DOT (3.61 days vs. 6.25 days; P<0.001) and decreased 30-day all-cause mortality (P=0.003) and infection-related mortality (P=0.002) were observed among patients in the accepted group compared with the rejected group. There was no significant difference in LOS, 14-day CDI and 30-day re-admission (all P>0.05). In conclusion, acceptance of early interventions recommended by ASP in SGH was associated with a reduction in DOT without compromising patient safety. This is evident even during empirical therapy when not all clinical information was available.

Prolonged infusion versus intermittent boluses of β-lactam antibiotics for treatment of acute infections: a meta-analysis

The clinical advantages of prolonged (extended/continuous) infusion remain controversial. Previous studies and reviews have failed to show consistent clinical benefits of extending the infusion time. This meta-analysis sought to determine whether prolonged β-lactam infusions were associated with a reduction in mortality and improvement in clinical success. A search of PubMed, EMBASE and The Cochrane Library for randomised controlled trials (RCTs) and observational studies comparing prolonged infusion with intermittent bolus administration of the same antibiotic in hospitalised adult patients was conducted. Primary outcomes evaluated were mortality and clinical success. A total of 29 studies with 2206 patients (18 RCTs and 11 observational studies) were included in the meta-analysis. Compared with intermittent boluses, use of prolonged infusion appeared to be associated with a significant reduction in mortality [pooled relative risk (RR) = 0.66, 95% confidence interval (CI) 0.53-0.83] and improvement in clinical success (RR = 1.12, 95% CI 1.03-1.21). Statistically significant benefit was supported by non-randomised studies (mortality, RR = 0.57, 95% CI 0.43-0.76; clinical success, RR = 1.34, 95% CI 1.02-1.76) but not by RCTs (mortality, RR = 0.83, 95% CI 0.57-1.21; clinical success, RR = 1.05, 95% CI 0.99-1.12). The positive results from observational studies, especially in the face of increasing antibiotic resistance, serve to justify the imperative need to conduct a large-scale, well-designed, multicentre RCT involving critically ill patients infected with high minimum inhibitory concentration pathogens to clearly substantiate this benefit.

Evaluation of Ertapenem use with impact assessment on extended-spectrum beta-lactamases (ESBL) production and gram-negative resistance in Singapore General Hospital (SGH)

Background

Ertapenem (preferred choice for ESBL-producing organisms) use exhibited an increasing trend from 2006 to 2008. As extensive use of ertapenem might induce the mutation of resistant bacteria strains to ertapenem, we aimed to assess the appropriateness and impact of ertapenem-use, on ESBL production, the trends of gram-negative bacterial resistance and on the utilization of other antibiotics in our institution.

Methods

Inpatients who received a dose of ertapenem during 1 January 2006 to 31 December 2008, were reviewed. Pertinent patient clinical data was extracted from the pharmacy databases and assessed for appropriateness based on dose and indication. Relevant data from Network for Antimicrobial Resistance Surveillance (Singapore) (NARSS) was extracted, to cross-correlate with ertapenem via time series to assess its impact on hospital epidemiology, trends of gram-negative resistance and consumption of other antibiotics from 2006 to mid-2010.

Results

906 cases were reviewed. Ertapenem therapy was appropriate in 72.4% (93.7% success rate). CNS adverse events were noted in 3.2%. Readmission rate (30-day) due to re-infection (same pathogen) was 5.5%. Fifty cases had cultures growing Pseudomonas aeruginosa within 30 days of ertapenem initiation, with 25 cases growing carbapenem-resistant Pseudomonas aeruginosa.

Ertapenem use increased from 0.45 DDD/100 patient days in 2006 to 1.2 DDD/100 patient days in mid-2010. Overall, the increasing trend of ertapenem consumption correlated with 1) increasing incidence-densities of ciprofloxacin-resistant/cephalosporin-resistant E. coli at zero time lag; 2) increasing incidence-densities of ertapenem-resistant Escherichia. coli and Klebsiella spp. at zero time lag; 3) increasing incidence-density of carbapenem-resistant Pseudomonas aeruginosa, at zero time lag.

Increasing ertapenem consumption was significantly correlated with decreasing consumption of cefepime (R² = 0.37344) 3 months later. It was significantly correlated with a decrease in imipenem consumption (R² = 0.31081), with no time lag but was correlated with subsequent increasing consumption of meropenem (R² = 0.4092) 6 months later.

Conclusion

Ertapenem use was appropriate. Increasing Ertapenem consumption did not result in a decreasing trend of ESBL producing enterobacteriaceae and could result in the selection for multi-drug resistant bacteria.

Risk factors, molecular epidemiology and outcomes of ertapenem-resistant, carbapenem-susceptible Enterobacteriaceae: a case-case-control study

Background

Increasing prevalence of ertapenem-resistant, carbapenem-susceptible Enterobacteriaceae (ERE) in Singapore presents a major therapeutic problem. Our objective was to determine risk factors associated with the acquisition of ERE in hospitalized patients; to assess associated patient outcomes; and to describe the molecular characteristics of ERE.

Methods

A retrospective case-case-control study was conducted in 2009 at a tertiary care hospital. Hospitalized patients with ERE and those with ertapenem-sensitive Enterobacteriaceae (ESE) were compared with a common control group consisting of patients with no prior gram-negative infections. Risk factors analyzed included demographics; co-morbidities; instrumentation and antibiotic exposures. Two parallel multivariate logistic regression models were performed to identify independent variables associated with ERE and ESE acquisition respectively. Clinical outcomes were compared between ERE and ESE patients.

Results

Twenty-nine ERE cases, 29 ESE cases and 87 controls were analyzed. Multivariate logistic regression showed that previous hospitalization (Odds ratio [OR], 10.40; 95% confidence interval [CI], 2.19–49.20) and duration of fluoroquinolones exposure (OR, 1.18 per day increase; 95% CI, 1.05–1.34) were unique independent predictors for acquiring ERE. Duration of 4^th-generation cephalosporin exposure was found to predict for ESE acquisition (OR, 1.63 per day increase; 95% CI, 1.05–2.54). In-hospital mortality rates and clinical response rates were significantly different between ERE and ESE groups, however ERE infection was not a predictor of mortality. ERE isolates were clonally distinct. Ertapenem resistance was likely to be mediated by the presence of extended-spectrum β-lactamases or plasmid-borne AmpC in combination with impermeability due to porin loss and/or efflux pumps.

Conclusion

Prior hospitalization and duration of fluoroquinolone treatment were predictors of ERE acquisition. ERE infections were associated with higher mortality rates and poorer clinical response rates when compared to ESE infections.