Bloodstream infections in the Intensive Care Unit

Performance of molecular tests for diagnosis of bloodstream infections in the clinical setting: a systematic literature review and meta-analysis

BACKGROUND

Rapid identification of bloodstream pathogens and associated antimicrobial resistance (AMR) profiles by molecular tests from positive blood cultures (PBCs) have the potential to improve patient management and clinical outcomes.

OBJECTIVES

A systematic review and meta-analysis were conducted to evaluate diagnostic test accuracy (DTA) of molecular tests from PBCs for detecting pathogens and AMR in the clinical setting.

METHODS

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DATA SOURCES

Medline, Embase, Cochrane, conference proceedings, and study bibliographies were searched.

STUDY ELIGIBILITY CRITERIA

Studies evaluating DTA of commercially available molecular tests vs. traditional phenotypic identification and susceptibility testing methods in patients with PBCs were eligible.

PARTICIPANTS

Patients with PBCs.

TESTS

Commercially available molecular tests.

REFERENCE STANDARD

Traditional phenotypic identification and susceptibility testing methods (standard of care, SOC).

ASSESSMENT OF RISK OF BIAS

Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2.

METHODS OF DATA SYNTHESIS

Summary DTA outcomes were estimated using bivariate random-effects models for gram-negative bacteria (GNB), gram-positive bacteria (GPB), yeast, GNB-AMR, GPB-AMR, and specific targets when reported by ≥ 2 studies (PROSPERO CRD42023488057).

RESULTS

Seventy-four studies including 24 590 samples were analysed, most of which had a low risk of bias. When compared with SOC, molecular tests showed 92-99% sensitivity, 99-100% specificity, 99-100% positive predictive value, and 97-100% negative predictive value for identifying total GNB (43 studies), GPB (38 studies), yeast (24 studies), GNB-AMR (35 studies), and GPB-AMR (39 studies). For individual pathogen targets, 93-100% sensitivity, 98-100% specificity, 86-100% positive predictive value, and 99-100% negative predictive value were estimated. Five of seven AMR genes had 91-99% sensitivity and 99-100% specificity. Sensitivity was lower for IMP (four studies; 62%; 95% CI, 34-83%) and VIM (four studies; 70%; 95% CI, 38-90%) carbapenemases, where genes were not detected or were not harboured in Pseudomonas aeruginosa (i.e. low prevalence). Performance of molecular tests in detecting AMR was generally comparable when grouped by geographical region (Europe, North America, and East Asia).

DISCUSSION

High DTA support the use of molecular tests in identifying a broad panel of pathogens and detecting AMR in GNB and GPB.

Biosensing for rapid detection of MDR, XDR and PDR bacteria

The emergence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR) bacteria poses a significant threat to global public health, complicating the management of infectious diseases and increasing morbidity and mortality rates. Rapid and sensitive detection of these resistant pathogens is crucial for effective treatment and infection control. This manuscript provides a comprehensive overview of various biosensor technologies developed for the rapid identification and quantification of MDR and XDR bacteria. We discuss the principles of operation, sensitivity, specificity, and practical applications of different biosensing platforms, including electrochemical, optical, and piezoelectric sensors. Additionally, we explore recent advancements in nanomaterials and microfluidics that enhance biosensor performance and enable point-of-care testing. The manuscript also addresses the challenges faced in the implementation of these technologies in clinical settings, such as regulatory hurdles and the need for standardization. A systematic literature review was conducted to identify relevant studies. Databases utilized include PubMed and Scopus, covering the time frame from 2015 to 2024. The literature screening criteria focused on the inclusion of only clinically validated studies to ensure the reliability and applicability of the findings. By highlighting the potential of biosensors to revolutionize the detection of drug-resistant bacteria, this work aims to inform researchers, clinicians, and policymakers about the critical role of innovative diagnostic tools in combating antibiotic resistance and improving patient outcomes.

Using interpretable machine learning to predict bloodstream infection and antimicrobial resistance in patients admitted to ICU: Early alert predictors based on EHR data to guide antimicrobial stewardship

Nosocomial infections and Antimicrobial Resistance (AMR) stand as formidable healthcare challenges on a global scale. To address these issues, various infection control protocols and personalized treatment strategies, guided by laboratory tests, aim to detect bloodstream infections (BSI) and assess the potential for AMR. In this study, we introduce a machine learning (ML) approach based on Multi-Objective Symbolic Regression (MOSR), an evolutionary approach to create ML models in the form of readable mathematical equations in a multi-objective way to overcome the limitation of standard single-objective approaches. This method leverages readily available clinical data collected upon admission to intensive care units, with the goal of predicting the presence of BSI and AMR. We further assess its performance by comparing it to established ML algorithms using both naturally imbalanced real-world data and data that has been balanced through oversampling techniques. Our findings reveal that traditional ML models exhibit subpar performance across all training scenarios. In contrast, MOSR, specifically configured to minimize false negatives by optimizing also for the F1-Score, outperforms other ML algorithms and consistently delivers reliable results, irrespective of the training set balance with F1-Score.22 and.28 higher than any other alternative. This research signifies a promising path forward in enhancing Antimicrobial Stewardship (AMS) strategies. Notably, the MOSR approach can be readily implemented on a large scale, offering a new ML tool to find solutions to these critical healthcare issues affected by limited data availability.

Comparing NGS-Based identification of bloodstream infections to traditional culture methods for enhanced ICU care: a comprehensive study

Background

Accurate identification of infectious diseases using molecular techniques, such as PCR and NGS, is well-established. This study aims to assess the utility of Bactfast and Fungifast in diagnosing bloodstream infections in ICU settings, comparing them against traditional culture methods. The objectives include evaluating sensitivity and specificity and identifying a wide range of pathogens, including non-culturable species.

Methods

We collected 500 non-duplicate blood samples from ICU patients between January 2023 and December 2023. Specimens underwent traditional culture, MALDI-TOF, VITEK®2 compact system, and NGS-based Bactfast and Fungifast analyses.

Results

Out of the 500 samples, 26.8% (n=134) showed bacterial growth via traditional culture methods, while 4.8% (n=24) were positive for fungal growth. MALDI-TOF and VITEK®2 compact system yielded comparable results, identifying 26.4% (n=132) of specimens with bacterial growth. NGS-based Bactfast detected bacterial presence in 38.2% (n=191) of samples, including non-culturable bacteria missed by traditional methods. However, NGS-based Fungifast showed concordant fungal detection rates with culture methods. Among identified pathogens by culture method included Klebsiella pneumoniae 20.89% (n=28), Enterococcus faecalis 18.65% (n=25), Escherichia coli 15.67% (n=21), Pseudomonas aeruginosa 12.68% (n=17), Acinetobacter baumannii 10.44% (n=14), various Streptococcus species 7.46% (n=10), Mycobacterium tuberculosis 6.71% (n=9), Mycobacterium abscessus 4.47% (n=6), and Salmonella spp 2.98% (n=4). Non-culture-based NGS identified additional (n=33) pathogens, including Klebsiella pneumoniae 27.27% (n=9), Bacteroides fragilis 21.21% (n=7), Aerococcus viridans 15.15% (n=5), Elizabethkingia anopheles 12.12% (n=4), Aeromonas salmonicida 9% (n=3), Clostridium 9% (n=3), and Bacteroides vulgatus 6% (n=2). Candida albicans was reported in 5% (n=24) of samples by both methods.

Conclusion

NGS-based Bactfast and Fungifast demonstrate high sensitivity in identifying a wide array of bacterial and fungal pathogens in ICU patients, outperforming traditional culture methods in detecting non-culturable organisms. These molecular assays offer rapid and comprehensive diagnostic capabilities, potentially improving clinical outcomes through timely and accurate pathogen identification.

Novel and Rapid Diagnostics for Common Infections in the Critically Ill Patient

There are several novel platforms that enhance detection of pathogens that cause common infections in the intensive care unit. These platforms have a sample to answer time of a few hours, are often higher yield than culture, and have the potential to improve antibiotic stewardship.

Bloodstream Infection in the Intensive Care Unit: Evolving Epidemiology and Microbiology

Bloodstream infections (BSIs) arising in the intensive care unit (ICUs) present a significant challenge and we completed a narrative review of the emerging literature on this issue. Multiple reports document that these infections are associated with substantial morbidity and mortality. Also, they can be caused by a variety of pathogens. Generally classified as either community or hospital in onset, or as either primary or secondary in origin, the microbiology of ICU BSIs varies across the globe. Gram-positive pathogens predominate in certain regions such as the United States while Gram-negative organisms occur more frequently in Europe, Asia, and Latin America. The incidence of ICU BSIs climbed during the recent pandemic. BSIs complicating the care of persons suffering from Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection significantly heighten the risk for death compared to patients who develop ICU BSIs but who are not infected with SARS-CoV-2. Furthermore, rates of antimicrobial resistance are generally increasing in ICU BSIs. This fact complicates attempts to ensure that the patient receives initially appropriate antimicrobial therapy and is of particular concern in Methicillin-resistant Staphylococcus aureus, Carbapenem-resistant Enterobacterales, and Acinetobacter baumannii. Fortunately, with respect to clinical application, preventive measures exist, and recent analyses suggest that increased collaboration between infectious disease specialists and intensivists can improve patient outcomes.

Performance of next-generation sequencing for diagnosis of blood infections by Klebsiella pneumoniae

Objective

Klebsiella pneumoniae (Kp) bloodstream infections (BSI) can be a life-threatening opportunistic infection. We aimed to evaluate the diagnostic accuracy of metagenomic next-generation sequencing (mNGS) for Kp BSI.

Methods

We retrospectively analyzed 72 patients suspected with bloodstream infection and mNGS Kp positive in peripheral blood, who were hospitalized in our hospital from January 2022 to January 2023. Clinical data and laboratory parameters were collected. All patients had blood drawn and other samples for blood mNGS, blood cultures (BC) and other cultures (OC). The accuracy of mNGS results was analyzed according to infection site, clinical indicators, therapeutic effect and routine culture results. The detection of pathogenic microorganisms by blood mNGS and routine culture was compared.

Results

Among 72 infection patients, 29 cases (40.28%) were BC positive, 43 cases (59.72%) were other culture (OC) positive, 16 cases (22.22%) were both BC and OC positive, 56 cases were positive for both mNGS and routine culture. Among the 56 double-positive cases, mNGS and conventional cultures were completely consistent in 27 cases, partially consistent in 15 cases, and completely inconsistent in 14 cases. Using the clinical diagnosis as the reference standard, There were 51 cases consistent with the results of mNGS with Kp BSI, the clinical consistency was 70.83% (51/72). The coincidence rate of mNGS and clinical diagnosis was higher than that of BC (54.17%, 39/72), indicating a statistically significant difference between the two methods (P<0.01).

Conclusions

Current evidence indicates that mNGS exhibits excellent accuracy for the diagnosis of Kp BSI. Although it cannot replace blood culture detection technology, it can be used as a supplement to provide stronger diagnostic capabilities for BSI and optimize treatment.

Tracking gut microbiome and bloodstream infection in critically ill adults

BACKGROUND

The gut microbiome is believed to contribute to bloodstream infection (BSI) via translocation of dominant gut bacteria in vulnerable patient populations. However, conclusively linking gut and blood organisms requires stringent approaches to establish strain-level identity.

METHODS

We enrolled a convenience cohort of critically ill patients and investigated 86 bloodstream infection episodes that occurred in 57 patients. Shotgun metagenomic sequencing was used to define constituents of their gut microbiomes, and whole genome sequencing and assembly was done on 23 unique bloodstream isolates that were available from 21 patients. Whole genome sequences were downloaded from public databases and used to establish sequence-identity distribution and define thresholds for unrelated genomes of BSI species. Gut microbiome reads were then aligned to whole genome sequences of the cognate bloodstream isolate and unrelated database isolates to assess identity.

RESULTS

Gut microbiome constituents matching the bloodstream infection species were present in half of BSI episodes, and represented >30% relative abundance of gut sequences in 10% of episodes. Among the 23 unique bloodstream organisms that were available for whole genome sequencing, 14 were present in gut at the species level. Sequence alignment applying defined thresholds for identity revealed that 6 met criteria for identical strains in blood and gut, but 8 did not. Sequence identity between BSI isolates and gut microbiome reads was more likely when the species was present at higher relative abundance in gut.

CONCLUSION

In assessing potential gut source for BSI, stringent sequence-based approaches are essential to determine if organisms responsible for BSI are identical to those in gut: of 14 evaluable patients in which the same species was present in both sites, they were identical in 6/14, but were non-identical in 8/14 and thus inconsistent with gut source. This report demonstrates application of sequencing as a key tool to investigate infection tracking within patients.

Comparison of bloodstream and non-bloodstream infections caused by carbapenem-resistant Klebsiella pneumoniae in the intensive care unit: a 9-year respective study

Background

Bloodstream infections (BSIs) caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) have received much attention. However, few studies have identified risk factors for CRKP BSIs in comparison to CRKP non-bloodstream infections (non-BSIs). This study aimed to compare the epidemiology, risk factors, and outcomes of CRKP BSIs and CRKP non-BSIs.

Methods

We conducted a retrospective study of patients infected with CRKP in the ICU from January 2012 to December 2020. Clinical characteristics and outcomes were compared between CRKP BSIs and CRKP non-BSIs. Predictors associated with 28-day all-cause mortality in CRKP-infected patients were also evaluated.

Results

326 patients infected with CRKP were enrolled, including 96 patients with CRKP BSIs and 230 with CRKP non-BSIs. The rates of CRKP BSIs in CRKP infections were generally raised from 2012 (12.50%) to 2020 (45.76%). Multivariate logistic analysis indicated that the use of carbapenems within the prior 90 days was an independent risk factor for CRKP BSIs (p = 0.019). Compared to CRKP non-BSIs, CRKP isolates in the CRKP BSI group were found to be non-susceptible to more tested carbapenems (p = 0.001). Moreover, the CRKP BSI group exhibited a higher mortality rate (p = 0.036). The non-susceptibility of CRKP isolates to more tested carbapenems (p = 0.025), a high SOFA score (p = 0.000), and the use of antifungal drugs within the prior 90 days (p = 0.018) were significant factors for 28-day all-cause mortality in CRKP-infected patients.

Conclusion

The proportion of CRKP BSI increased progressively in CRKP-infected patients over 9 years. The use of carbapenems within the prior 90 days was an independent risk factor for the development of CRKP BSIs. The non-susceptibility of CRKP isolates to more tested carbapenems and a higher mortality rate were found in the CRKP BSI group.

Evaluation of the relationship between procalcitonin level and the causative pathogen in intensive care patients with sepsis

Aim: This study was designed to investigate how procalcitonin (PCT) levels are affected by different pathogens in patients with sepsis. Materials & methods: A total of 110 Gram-positive sepsis, 62 Gram-negative sepsis and 27 fungal sepsis patients were included in the study. Kaplan-Meier and ROC curve analysis was performed to assess PCT levels. Results: PCT levels were 2.36 ng/ml in Gram-negative patients, 0.79 ng/ml in Gram-positive patients and 0.89 ng/ml in fungal patients. The area under the curve for PCT was 0.608, the cutoff value was 1.34, sensitivity was 56.50% the specificity was 56.50%. Conclusion: PCT survival levels of 7.71 ng/ml in Gram-negative patients, 2.65 ng/ml in Gram-positive patients and 1.16 ng/ml in fungal patients can be evaluated to predict survival.

[Impact of the first year of the COVID-19 pandemic on the epidemiology of invasive infections (bacteremia) in the hospitals of the Assistance Publique-Hôpitaux de Paris]

Introduction

The COVID-19 pandemic has led to a massive influx of patients suffering from severe forms of the disease into hospitals, often requiring intensive care (vascular catheters, ventilation, etc.) which exposes them to high risks of nosocomial infections, particularly invasive infections (bacteremia).

Method

The impact of the COVID-19 pandemic on the epidemiology of bacteremia in 2020 was analysed in 25 hospitals of the Assistance Publique-Hôpitaux de Paris (AP-HP, approximately 14,000 beds, covering the Île-de-France region). Up to a quarter of patients admitted to AP-HP during the March-April period (peak of the 1st wave) were infected with COVID-19. The incidence over 100 admissions of bacteraemia increased overall compared to previous years: by 24% in March 2020 and by 115% in April.

Results

The evolution of the incidence of bacteremia was not the same for 2 groups of microorganisms with very different ecologies. For the "hospital" type microorganisms classically responsible for nosocomial infections, the incidence increased significantly in March-April 2020: Klebsiella pneumoniae (×2.3), Pseudomonas aeruginosa (×2.4), Staphylococcus aureus (×2.4), enterococci (×3.4), yeasts (×2.7). Two thirds of the bacteremias caused by these microorganisms were considered as acquired during hospitalization. Importantly, there was also a sharp increase in the incidence of bacteremia caused by antibiotic-resistant strains. The antibiotics used as indicators were the 3rd generation cephalosporins (3GCs), major antibiotics in the treatment of serious infections used for monitoring bacterial resistance in Europe. For example, the incidence of bacteremia with 3GC-resistant strains increased threefold in April 2020 for K. pneumoniae. During the same period, the consumption of 3GC increased sharply in the same hospitals (+131% in March and +148% in April). For Streptococcus pneumoniae (pneumococcus) and Streptococcus pyogenes (group A hemolytic streptococcus), two pathogens responsible for mainly community and respiratory-transmitted infections, the pandemic had the opposite effect. There was a decrease in incidence in 2020 by 34% and 28% respectively for these two species, particularly in the spring when strict containment, physical distancing and mask-wearing measures were in place. A slight re-emergence of infections with these two species occurred in the summer of 2020 after the relaxation of prevention measures. In contrast to what was seen above, 4/5 of the bacteremias caused by these two species were considered as community-acquired.

Conclusion

The COVID-19 pandemic which had a strong impact on hospital management and social organization in the general population, had opposite impacts on the incidence of bacteremia depending on the pathogens and their mode of transmission.

Bacterial bloodstream infection in critically ill patients with COVID-19: a retrospective cohort study

Background

Intensive care unit (ICU) patients with coronavirus disease 2019 (COVID-19), have a high risk of developing bloodstream infections (BSIs). However, the characteristics of and risk factors for BSIs in these patients remain unclear.

Objective

We aimed to identify prevalent causative pathogens of BSI and related factors in critically ill patients with COVID-19.

Design

This was a single-center, retrospective cohort study.

Methods

We analyzed the clinical characteristics and outcomes of 201 ICU patients with COVID-19. Logistic regression analysis was conducted to identify factors associated with BSI occurrence. Furthermore, we identified the primary causative pathogens of BSIs. The study outcomes were death or ICU discharge.

Results

Among the 201 included patients, 43 (21.4%) patients developed BSI. The mortality rate was non-significantly higher in the BSI group than in the BSI group (65.1% versus 58.9%, p = 0.487). There were significant between-group differences in the obesity prevalence and sex distribution, but not corticosteroid usage. BSI occurrence was significantly associated with duration of mechanical ventilation (MV), presence of ventilator-associated pneumonia, use of neuromuscular blocking agents, length of stay in ICU (ICU LOS), high body mass index (BMI), and male sex. The main causative pathogens were Klebsiella pneumoniae, Acinetobacter baumannii, and Enterococcus faecalis. Multi-drug-resistant pathogens were found in 87% of cases. Regardless of the origin, the common risk factors for BSI were ICU LOS and MV duration. All BSIs were acquired within the hospital setting, with ≈60% of the cases being primary BSIs. A small proportion of the BSI cases were catheter-related (four cases, 6.2%). Ventilator-associated pneumonia and urinary tract infections were present in 25% and 9.4% of the BSI cases, respectively. On average, the first positive blood culture appeared ≈11.4 (±9.7) days after ICU admission.

Conclusion

Elucidating the risk factors for and common pathogens of BSI can inform prompt management and prevention of BSIs.

Rapid and precise identification of bloodstream infections using a pre-treatment protocol combined with high-throughput multiplex genetic detection system

Background

Bloodstream infection (BSI) is a life-threatening condition with high morbidity and mortality rates worldwide. Early diagnosis of BSI is critical to avoid the unnecessary application of antimicrobial agents and for proper treatment. However, the current standard methods based on blood culture are time-consuming, thus failing to provide a timely etiological diagnosis of BSI, and common PCR-based detection might be inhibited by matrix components.

Methods

The current study explored an integrated pre-analytical treatment protocol for whole blood samples, wherein pathogens are enriched and purified by incubation and concentration, and inhibitors are inactivated and removed. Further, this study developed and evaluated a novel high-throughput multiplex genetic detection system (HMGS) to detect 24 of the most clinically prevalent BSI pathogens in blood culture samples and pre-treated whole blood samples. The specificity and sensitivity were evaluated using related reference strains and quantified bacterial/fungal suspensions. The clinical utility of BSI-HMGS combined with the pre-analytical treatment protocol was verified using blood cultures and whole blood samples.

Results

The combined pre-treatment protocol and BSI-HMGS was highly specific for target pathogens and possessed a low detection limit for clinical whole blood samples. The pre-treatment protocol could deplete the PCR inhibitors effectively. For blood culture samples, the current method showed 100.0% negative percent agreements and > 87.5% positive percent agreements compared to the reference results based on blood culture findings. For whole blood samples, the current method showed 100.0% negative percent agreements and > 80.0% positive percent agreements compared to the reference results for most pathogens. The turnaround time was ≤ 8 h, and all the procedures could be conducted in a general clinical laboratory.

Conclusion

The BSI-HMGS combined with the pre-treatment protocol was a practical and promising method for early and precise detection of BSIs, especially for areas without access to advanced medical facilities.

Antimicrobial Treatment of Pseudomonas aeruginosa Severe Sepsis

Pseudomonas aeruginosa is a pathogen often encountered in a healthcare setting. It has consistently ranked among the most frequent pathogens seen in nosocomial infections, particularly bloodstream and respiratory tract infections. Aside from having intrinsic resistance to many antibiotics, it rapidly acquires resistance to novel agents. Given the high mortality of pseudomonal infections generally, and pseudomonal sepsis particularly, and with the rise of resistant strains, treatment can be very challenging for the clinician. In this paper, we will review the latest evidence for the optimal treatment of P. aeruginosa sepsis caused by susceptible as well as multidrug-resistant strains including the difficult to treat pathogens. We will also discuss the mode of drug infusion, indications for combination therapy, along with the proper dosing and duration of treatment for various conditions with a brief discussion of the use of non-antimicrobial agents.

Novel and Rapid Diagnostics for Common Infections in the Critically Ill Patient

There are several novel platforms that enhance detection of pathogens that cause common infections in the intensive care unit. These platforms have a sample to answer time of a few hours, are often higher yield than culture, and have the potential to improve antibiotic stewardship.

Bacteriological aspects of bacteremia in the intensive care unit of the Mohammed V Military Hospital: 10 months prospective study

Introduction

Bacteremia is responsible for high rates of morbidity and mortality. The increasing prevalence of multidrug-resistant (MDR) bacteria in intensive care units (ICU) is a growing concern. Hence, prior knowledge of bacterial epidemiology and resistance phenotypes is required to optimize these infections' management. The objective of this study was to determine the epidemiological profile of bacteremia in ICU settings, as well as the place occupied by MDR bacteria in these infections.

Methods

It is a prospective study carried out over 10 months on episodes of bacteremia in the ICU of Mohammed V Military Teaching Hospital (Rabat, Morocco). Microorganism growth was detected using fluorescent technology, species identification was based on morphological and biochemical characteristics. Antimicrobial susceptibility testing was performed following the recommendations of the Antibiogram Committee of the French Society of Microbiology (CA-SFM) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST).

Results

Among 504 hospitalized patients, sixty-one (12.1%) presented at least one episode of bacteremia. Forty patients (65.6% of bacteremic patients) presented at least one episode of bacteremia due to MDR bacteria. Male gender, cardiovascular diseases, diabetes and previous hospitalization were significant risk factors for the acquisition of MDR bacteremia. Isolated bacteria were mainly Gram-negative bacilli (GNB) (n = 62; 68.9%) dominated by Acinetobacter baumannii (n = 19; 21.1%) and Klebsiella pneumoniae (n = 16; 17.8%). MDR bacteria were represented by multi-resistant Acinetobacter baumannii (n = 19; 44.2%), extended-spectrum beta-lactamases-producing Enterobacterales (n = 9; 20.9%) and carbapenem-resistant Enterobacterales (n = 7; 16.3%). Carbapenems (n = 40; 65.6%), Aminoglycosides (n = 32; 52.5%) and Polypeptides (n = 24; 39.3%) were the most used antimicrobials. Mortality rates were 66.6% (n = 40) and 85% (n = 43) in patients with non MDR bacteremia and MDR bacteremia respectively.

Conclusion

Limiting the spread of MDR bacteria and improving the management of bacteremic patients require continuous monitoring of bacteremia as well as adapting the therapeutic and preventive strategy.

Secondary bloodstream infection in critically ill patients with COVID-19

Objective

Secondary infection, especially bloodstream infection, is an important cause of death in critically ill patients with COVID-19. We aimed to describe secondary bloodstream infection (SBI) in critically ill adults with COVID-19 in the intensive care unit (ICU) and to explore risk factors related to SBI.

Methods

We reviewed all SBI cases among critically ill patients with COVID-19 from 12 February 2020 to 24 March 2020 in the COVID-19 ICU of Jingmen First People's Hospital. We compared risk factors associated with bloodstream infection in this study. All SBIs were confirmed by blood culture.

Results

We identified five cases of SBI among the 32 patients: three with Enterococcus faecium, one mixed septicemia (E. faecium and Candida albicans), and one C. parapsilosis. There were no significant differences between the SBI group and non-SBI group. Significant risk factors for SBI were extracorporeal membrane oxygenation, central venous catheter, indwelling urethral catheter, and nasogastric tube.

Conclusions

Our findings confirmed that the incidence of secondary infection, particularly SBI, and mortality are high among critically ill patients with COVID-19. We showed that long-term hospitalization and invasive procedures such as tracheotomy, central venous catheter, indwelling urethral catheter, and nasogastric tube are risk factors for SBI and other complications.

Predictors of multidrug resistant Pseudomonas aeruginosa involvement in bloodstream infections

PURPOSE OF REVIEW

In the last decades, there has been a worldwide worrisome spread of multidrug resistant (MDR) Pseudomonas aeruginosa. Treatment of these infections is challenging, in part due to the lack of therapeutic options, and the importance of prescribing an adequate empirical treatment. Bacteraemia is one of the most severe infections, with mortality rates ranging between 20 and 40%.

RECENT FINDINGS

It is key to understand which patients are at a higher risk of MDR P. aeruginosa bloodstream infection (BSI) to better direct empirical therapies and improve overall survival. Immunocompromised patients are among the most vulnerable for the worst outcomes. Environmental exposure, integrity of the microbiota, and host immunity are the key determinants for the initial colonization and expansion on mucosal surfaces and potential invasion afterwards by MDR P. aeruginosa.

SUMMARY

Available data suggest that high colonization pressure (settings with high prevalence like intensive care units), disruption of healthy microbiota (prior use of antibiotics, in particular fluoroquinolones), immunosuppression (neutropenia) and breaking natural barriers (venous or urine catheters), are the main risk factors for MDR P. aeruginosa BSI.

Duplex dPCR System for Rapid Identification of Gram-Negative Pathogens in the Blood of Patients with Bloodstream Infection: A Culture-Independent Approach

Early and accurate detection of pathogens is important to improve clinical outcomes of bloodstream infections (BSI), especially in the case of drug-resistant pathogens. In this study, we aimed to develop a culture-independent digital PCR (dPCR) system for multiplex detection of major sepsiscausing gram-negative pathogens and antimicrobial resistance genes using plasma DNA from BSI patients. Our duplex dPCR system successfully detected nine targets (five bacteria-specific targets and four antimicrobial resistance genes) through five reactions within 3 hours. The minimum detection limit was 50 ag of bacterial DNA, suggesting that 1 CFU/ml of bacteria in the blood can be detected. To validate the clinical applicability, cell-free DNA samples from febrile patients were tested with our system and confirmed high consistency with conventional blood culture. This system can support early identification of some drug-resistant gram-negative pathogens, which can help improving treatment outcomes of BSI.

Drug Susceptibility and Molecular Epidemiology of Klebsiella pneumoniae Bloodstream Infection in ICU Patients in Shanghai, China

Background: Bloodstream infections (BSIs) are recognized as important nosocomial infections. Klebsiella pneumoniae is one of the major causes of bacteremia. This retrospective study focused on drug susceptibility and molecular epidemiology of K. pneumoniae isolated from intensive care unit (ICU) patients with BSI in Shanghai, China.

Methods: Consecutive K. pneumoniae isolates were collected from ICU patients. Antibiotic susceptibility testing was conducted by the broth microdilution method. PCR was performed to detect antimicrobial resistance genes. We also completed multilocus sequence typing (MLST) and GoeBURST was used to analyze the result of MLST.

Results: A total of 78 K. pneumoniae isolates were enrolled. K. pneumoniae from ICU-BSIs were highly resistant to almost all common antibiotics. The most frequent resistance determinants responsible for extended-spectrum β-lactamase (ESBL) producers were bla_CTX−M−14, bla_CTX−M−15, and bla_CTX−M−55. KPC was the only enzyme, which was detected by the carbapenemase producers. The most principal sequence types (STs) were ST11, ST15, and ST23.

Conclusion: This study presents for the first time the antibiotic resistance phenotype and molecular epidemiology of K. pneumoniae isolated from ICU patients with BSIs in Shanghai. ICU-BSI K. pneumoniae is characteristic of a high resistance rate. The occurrence of the KPC-2 enzyme may result from nosocomial clonal dissemination of ST11 K. pneumoniae.

Surging bloodstream infections and antimicrobial resistance during the first wave of COVID-19: a study in a large multihospital institution in the Paris region

Objectives

This study measured the impact of the first wave of COVID-19 pandemic (COVID-19) (March–April 2020) on the incidence of bloodstream infections (BSIs) at Assistance Publique – Hôpitaux de Paris (APHP), the largest multisite public healthcare institution in France.

Methods

The number of patient admission blood cultures (BCs) collected, number of positive BCs, and antibiotic resistance and consumption were analysed retrospectively for the first quarter of 2020, and also for the first quarter of 2019 for comparison, in 25 APHP hospitals (ca. 14 000 beds).

Results

Up to a fourth of patients admitted in March–April 2020 in these hospitals had COVID-19. The BSI rate per 100 admissions increased overall by 24% in March 2020 and 115% in April 2020, and separately for the major pathogens (Escherichia coli, Klebsiella pneumoniae, enterococci, Staphylococcus aureus, Pseudomonas aeruginosa, yeasts). A sharp increase in the rate of BSIs caused by microorganisms resistant to third-generation cephalosporins (3GC) was also observed in March–April 2020, particularly in K. pneumoniae, enterobacterial species naturally producing inducible AmpC (Enterobacter cloacae...), and P. aeruginosa. A concomitant increase in 3GC consumption occurred.

Conclusions

The COVID-19 pandemic had a strong impact on hospital management and also unfavourable effects on severe infections, antimicrobial resistance, and laboratory work diagnostics.

Antibiotic sensitivity/resistance pattern of hospital acquired blood stream infection in children cancer patients: A retrospective study

BACKGROUND

The literature shows a growing emphasis on understanding the local patterns of antimicrobial resistance (AMR). We aimed to evaluate the spectrum of local microorganisms that cause bloodstream infections (BSI) and their AMR patterns in an Egyptian institution treating children with cancer.

METHODS

We conducted a single-centre, retrospective, study on children with confirmed primary, hospital-acquired, BSIs over one year. The microbiological examination of blood samples was done according to the Clinical and Laboratory Standards Institute. The antibiotic sensitivity test was done using VITEK® 2 system.

RESULTS

We retrieved the data of 607 children with a median age of 5 (0.25-18) years old. The most encountered diagnosis was acute lymphoblastic leukaemia (40%). Most identified microorganisms were gram-negative bacilli, mainly Escherichia coli (27.8%), followed by Klebsiella pneumoniae (12.2%). Gram-negative bacilli showed high resistance to piperacillin/tazobactam, levofloxacin, and meropenem. The lowest resistance rates for Gram-negative bacilli isolates were noted for colistin and tigecycline. Similarly, the gram-positive cocci showed high resistance to ampicillin/sulbactam, cefoxitin, and clindamycin; and low resistance regarding vancomycin and linezolid.

CONCLUSION

Resistance proportions (pattern) were similar to those reported in other countries with a higher distribution of E coli and a growing resistance to levofloxacin. Further investigation of the predisposing factors and the development of more effective strategies for the prevention of BSI should be a significant public health priority.

Metagenomic Next-Generation Sequencing of Bloodstream Microbial Cell-Free Nucleic Acid in Children With Suspected Sepsis in Pediatric Intensive Care Unit

Bloodstream infection is a life-threatening complication in critically ill patients. Multi-drug resistant bacteria or fungi may increase the risk of invasive infections in hospitalized children and are difficult to treat in intensive care units. The purpose of this study was to use metagenomic next-generation sequencing (mNGS) to understand the bloodstream microbiomes of children with suspected sepsis in a pediatric intensive care unit (PICU). mNGS were performed on microbial cell-free nucleic acid from 34 children admitted to PICU, and potentially pathogenic microbes were identified. The associations of serological inflammation indicators, lymphocyte subpopulations, and other clinical phenotypes were also examined. mNGS of blood samples from children in PICU revealed potential eukaryotic microbial pathogens. The abundance of Pneumocystis jirovecii was positively correlated with a decrease in total white blood cell count and immunodeficiency. Hospital-acquired pneumonia patients showed a significant increase in blood bacterial species richness compared with community-acquired pneumonia children. The abundance of bloodstream bacteria was positively correlated with serum procalcitonin level. Microbial genome sequences from potential pathogens were detected in the bloodstream of children with suspected sepsis in PICU, suggesting the presence of bloodstream infections in these children.

Clinical and Microbiological Outcomes of Ceftazidime-Avibactam Treatment in Adults with Gram-Negative Bacteremia: A Subset Analysis from the Phase 3 Clinical Trial Program

Introduction

This exploratory analysis assessed efficacy and safety outcomes in patients with Gram-negative bacteremia treated with ceftazidime-avibactam or comparator across five phase 3, randomized, controlled, multi-center trials in adults with complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI)/pyelonephritis, hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP).

Methods

In each trial, RECLAIM and RECLAIM 3 (cIAI; NCT01499290/NCT01726023), REPRISE (cIAI/cUTI; NCT01644643), RECAPTURE (cUTI; NCT01595438/NCT01599806), and REPROVE (HAP/VAP; NCT01808092), patients were randomized 1:1 to intravenous ceftazidime-avibactam (plus metronidazole for those with cIAI) or comparators (carbapenems in > 97% patients) for 5–21 days. Efficacy assessments included clinical and microbiological responses at the test-of-cure visit in the pooled Gram-negative extended microbiologically evaluable (GNeME) population (bacteremia subset). Safety outcomes were summarized for patients with positive bacterial blood culture(s) at baseline who received ≥ 1 dose of study treatment.

Results

The overall safety population included 4050 patients (ceftazidime-avibactam, n = 2024; comparator, n = 2026). The GNeME population (bacteremia subset) comprised 101 patients (ceftazidime-avibactam, n = 54; comparator, n = 47). Clinical cure rates (all indications combined) were 47/54 (87.0%) for ceftazidime-avibactam and 39/47 (83.0%) for comparators; favorable microbiological response rates were 43/54 (79.6%) and 32/47 (68.1%), respectively. Clinical and microbiological responses in the bacteremia subset were generally similar to those in the overall set. The pattern of adverse events in patients with bacteremia was similar between treatment groups and was consistent with the known safety profile of ceftazidime-avibactam.

Conclusion

This analysis provides supportive evidence of the efficacy and safety of ceftazidime-avibactam in patients with Gram-negative bacteremia associated with cIAI, cUTI/pyelonephritis, or HAP/VAP.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00506-7.

Hospital-Acquired Blood Stream Infection in an Adult Intensive Care Unit

Background

Hospital-acquired blood stream infections are a common and serious complication in critically ill patients.

Methods

A retrospective case series was undertaken investigating the incidence and causes of bacteraemia in an adult intensive care unit with a high proportion of postoperative cardiothoracic surgical and oncology patients.

Results

405 eligible patients were admitted to the intensive care unit over the course of nine months. 12 of these patients developed a unit-acquired blood stream infection. The average Acute Physiology And Chronic Health Evaluation II (APACHE II) score of patients who developed bacteraemia was greater than that of those who did not (19.8 versus 16.8, respectively). The risk of developing bacteraemia was associated with intubation and higher rates of invasive procedures. The mortality rate amongst the group of patients that developed bacteraemia was 33%; this is in contrast to the mortality rate in our unit as 27.2%. There was a higher proportion of Gram-negative bacteria isolated on blood cultures (9 out of 13 isolates) than in intensive care units reported in other studies.

Conclusion

Critical-care patients are at risk of secondary bloodstream infection. This study highlights the importance of measures to reduce the risk of infection in the intensive-care setting, particularly in patients who have undergone invasive procedures.

Molecular detection of extensively drug-resistant Salmonella Typhi and carbapenem-resistant pathogens in pediatric septicemia patients in Pakistan - a public health concern

Aim: To determine the prevalence of multidrug (MDR) and extensively drug-resistant (XDR) pathogens from pediatric blood samples Methods: In total, 4543 children's blood samples were processed in the BacT/ALERT system. Confirmation of the isolates and MIC was determined in VITEK® 2 system. Molecular identification of blaIMP, blaVIM and blaOXA-48 was done by PCR. Results: Of 4543 blood cultures, 458 (10%) were positive for bacterial growth and Salmonella Typhi (415; 90%) remained the primary pathogens. Antibiogram revealed 208 (50.1%) and 137 (33%) were MDR and XDR S. Typhi, respectively. Klebsiella pneumoniae displayed 46% resistance to imipenem. One hundred twelve (81.7%) XDR Typhi were positive for blaCTXM, whereas 14 (66.6%) blaVIM were found in carbapenem-resistant bacteria. Conclusion: A high prevalence of MDR and XDR pathogens was found in peads blood culture.

An Artificial Intelligence Approach to Bloodstream Infections Prediction

This study aimed to develop an early prediction model for identifying patients with bloodstream infections. The data resource was taken from 2015 to 2019 at Taichung Veterans General Hospital, and a total of 1647 bloodstream infection episodes and 3552 non-bloodstream infection episodes in the intensive care unit (ICU) were included in the model development and evaluation. During the data analysis, 30 clinical variables were selected, including patients’ basic characteristics, vital signs, laboratory data, and clinical information. Five machine learning algorithms were applied to examine the prediction model performance. The findings indicated that the area under the receiver operating characteristic curve (AUROC) of the prediction performance of the XGBoost model was 0.825 for the validation dataset and 0.821 for the testing dataset. The random forest model also presented higher values for the AUROC on the validation dataset and testing dataset, which were 0.855 and 0.851, respectively. The tree-based ensemble learning model enabled high detection ability for patients with bloodstream infections in the ICU. Additionally, the analysis of importance of features revealed that alkaline phosphatase (ALKP) and the period of the central venous catheter are the most important predictors for bloodstream infections. We further explored the relationship between features and the risk of bloodstream infection by using the Shapley Additive exPlanations (SHAP) visualized method. The results showed that a higher prothrombin time is more prominent in a bloodstream infection. Additionally, the impact of a lower platelet count and albumin was more prominent in a bloodstream infection. Our results provide additional clinical information for cut-off laboratory values to assist clinical decision-making in bloodstream infection diagnostics.

Blood Stream Infections from MDR Bacteria

BACKGROUND

Bloodstream infections (BSIs) constitute a growing public health concern, are among the most severe nosocomial pathologies, and are considered a worldwide cause of unfaithful outcomes, increasing treatment costs and diagnostic uncertainties. BSIs are one of the most frequent lethal conditions that are managed in intensive care units (ICUs). In the case of septic shock, immune deficiency, and delayed treatment, even with adequate antimicrobial therapy and/or source control, the outcomes are often unfavorable.

METHODS

this review article summarizes the epidemiological and microbiological characteristics of BSIs with a particular focus on ICU acquired BSIs (ICU-BSIs), which are usually caused by multidrug-resistant (MDR) pathogens. For this reason, their antimicrobial resistance patterns and therapeutic options have also been compiled.

RESULTS

ICU-acquired BSIs prevail in 5-7% of ICU patients. Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosae are the pathogens most often responsible for MDR infections. MDR Enterobacteriaceae have seen their prevalence increase from 6.2% (1997-2000) to 15.8% (2013-2016) in recent years.

CONCLUSIONS

Considering that prevention and treatment of sepsis is nowadays considered a global health priority by the World Health Organization, it is our obligation to invest more resources into solving or reducing the spread of these unfaithful infections. It is relevant to identify patients with risk factors that make them more susceptible to BSIs, to guarantee earlier molecular or microbiological diagnoses, and more rapidly appropriate treatment by using de-escalation strategies where possible.

Activity of imipenem/relebactam and comparators against gram-negative pathogens from patients with bloodstream infections in the United States and Canada - SMART 2018-2019

Bloodstream infections (BSI) are often caused by drug-resistant pathogens, and novel antimicrobials are needed. We examined the activity of imipenem/relebactam against BSI pathogens from US and Canada: >99% of non-Morganellaceae Enterobacterales, including 100% of MDR isolates, and >94% of Pseudomonas aeruginosa were imipenem/relebactam-susceptible. Imipenem/relebactam could provide an important treatment option.

Bacteriological Profile and Antimicrobial Susceptibility Patterns of Bloodstream Infection at Kigali University Teaching Hospital

BACKGROUND

Worldwide, bacterial bloodstream infections (BSIs) constitute an important cause of morbidity and mortality in clinical settings. Due to the limited laboratory facilities in sub-Saharan Africa, poor diagnosis of BSIs results in poor clinical outcomes and leads to a risk of antimicrobial resistance. The present work was carried out to describe the microbiological features of BSIs using the data collected from Centre Hospitalier Universitaire de Kigali (CHUK).

METHODS

A retrospective study was carried out at CHUK. The blood culture results of 2,910 cases - from adults, children and infants - were reviewed in the Microbiology service from October 2017 to October 2018. The following variables were considered: age, gender, admitting department, blood culture results, and antimicrobials sensitivity test results. Data were entered and analyzed using Microsoft Excel 2013.

RESULTS

Twelve percent (341/2,910) of blood culture results reviewed were positive with 108 (31.7%) Gram positive bacteria and 233 (68.3%) Gram negative bacteria. The most prevalent pathogens were Klebsiella pneumoniae 108 (31.7%) and Staphylococcus aureus 100 (29.3%). This study revealed a high resistance to commonly prescribed antibiotics such as penicillin, trimethoprim sulfamethoxazole, and Ampicillin with 91.8, 83.3, and 81.8% of resistance, respectively. However, bacteria were sensitive to imipenem and vancomycin with 98.1 and 94.3% of sensitivity, respectively. The pediatrics and neonatology departments showed a high number of positive culture with 97/341 (28.4%), and 93/341 (27%) respectively. The overall prevalence of multidrug resistance was 77.1%.

CONCLUSION

The prevalence of bacterial pathogens in BSIs was found to be high. The antibiotic resistance to the commonly used antibiotics was high. Appropriate treatment of BSIs should be based on the current knowledge of bacterial resistance pattern. This study will help in formulating management of diagnostic guidelines and antibiotic policy.

Gram-negative bacilli bacteremia: a 7 year retrospective study in a referral Brazilian tertiary-care teaching hospital

Introduction. Bloodstream infection is one of the most frequent and challenging hospital-acquired infections and it is associated with high morbidity, mortality and additional use of healthcare resources.Hypothesis/Gap Statement: Bloodstream infections have consequences for the patient, such as the evolution to mortality and inappropriate empirical antibiotic prescription, especially when caused by multidrug-resistant Gram-negative bacilli.Objective. To assess the impact of bloodstream infection and the status of multidrug resistance (MDR) in the evolution of patients who received inappropriate initial antibiotic therapy.Methods. A retrospective surveillance was conducted on nosocomial bloodstream infections caused by Gram-negative bacilli (GNB) from January 2012 to December 2018 in an adult intensive care unit of a Brazilian tertiary teaching hospital.Results. We identified 270 patients with GNB nosocomial bacteremia. Non-survivors were older (with an average age of 58.8 years vs 46.9 years, P=<0.0001), presented more severe illnesses, were immunosuppressed (73.7 vs 37.6%, P=<0.0001), were more likely to have septic shock (55.8 vs 22.4%, P=<0.0001) and had an increased usage of mechanical ventilators (98.6 vs 89.6%, P=0.0013) than survivors. In a logistic regression model, inappropriate empirical antibiotic therapy was not an independent predictor of mortality, different from mechanical ventilator (P=<0.0001; OR=28.0; 95% CI=6.3-123.6), septic shock (P=0.0051; OR=2.5; 95% CI=1.3-4.9) and immunosuppression (P=0.0066; OR=2.6; 95% CI=1.3-5.2). In contrast, in a separate model, MDR was strongly associated with the prescription of inappropriate initial antibiotic therapy (P=0.0030; OR=5.3; 95% CI=1.7-16.1). The main isolated pathogens were Acinetobacter baumannii (23.6 %) and Klebsiella pneumoniae (18.7 %). The frequency of MDR organisms was high (63.7 %), especially among non-fermenting bacilli (60.9 %), highlighting A. baumannii (81.6 %) and Pseudomonas aeruginosa (41.8 %).Conclusion. Illness severity (septic shock and immunosuppression) and mechanical ventilation were identified as predictors of mortality. Additionally, MDR was a major determinant of inappropriate antibiotic empirical therapy, but not associated with mortality, and both characteristics were not statistically associated with death.

Reversing the Trend of Antimicrobial Resistance in ICU: Role of Antimicrobial and Diagnostic Stewardship

Background

Increasing antimicrobial resistance (AMR) among common bacteria combined with the slow development of new antibiotics has posed a challenge to clinicians.

Aim and objective

To demonstrate whether antimicrobial and diagnostic stewardship program (ASP and DSP)-related interventions improve antibiotic susceptibilities among common bacteria causing bloodstream infections (BSI) in patients admitted to the intensive care unit (ICU) and whether these resulted in changes in the volume of antimicrobial consumption.

Materials and methods

We compared the susceptibility patterns of gram-negative bacteria (GNB) and gram-positive cocci (GPC) causing BSI and changes in the volume of antibiotics prescribed for the same before and after 2017 by a retrospective analysis.

Results

Postintervention, there was increased susceptibility of all GNBs to aminoglycosides; Escherichia coli and Klebsiella spp. to beta-lactambeta-lactamase inhibitors (BLBLI) combinations; and Klebsiella spp. and Pseudomonas spp. to carbapenems. Acinetobacter spp., Klebsiella spp., and Pseudomonas spp. showed improved susceptibility to doxycycline, whereas E. coli and Klebsiella spp. showed significantly improved susceptibility to fluoroquinolones. Among GPCs, there was increased susceptibility of Staphylococcus aureus (levofloxacin, clindamycin, and aminoglycoside), coagulase-negative S. aureus (CoNS) (chloramphenicol, levofloxacin, clindamycin, and aminoglycoside), and enterococci (chloramphenicol, levofloxacin, and clindamycin). There was a significant reduction in usage of antimicrobials for the treatment of GPCs (linezolid, doxycycline, chloramphenicol, levofloxacin, BLBLI, macrolide, and cephalosporin) and GNBs (levofloxacin, cephalosporin, carbapenem, and colistin), which caused BSI.

Conclusion

The present study illustrated that combined ASP and DSP interventions successfully reversed the resistance pattern of organisms causing BSI and resulted in a reduction in antibiotic utilization.

How to cite this article

Agarwal J, Singh V, Das A, Nath SS, Kumar R, Sen M. Reversing the Trend of Antimicrobial Resistance in ICU: Role of Antimicrobial and Diagnostic Stewardship. Indian J Crit Care Med 2021;25(6):635-641.

Optimal Antibiotic Duration for Bloodstream Infections Secondary to Intraabdominal Infection

BACKGROUND

Bloodstream infections (BSIs) secondary to intraabdominal infections (IAIs) are common in the intensive care unit (ICU). The Surgical Infection Society guidelines recommend treatment duration after achieving source control in patients with secondary bacteremia; however, literature supporting this recommendation is limited. The purpose of this study was to compare outcomes in patients who received shorter versus extended duration of antibiotics for bacteremia secondary to IAI.

MATERIALS AND METHODS

A retrospective cohort analysis was conducted in adult surgical ICU patients (n = 42) with BSIs and source control procedure(s) for IAI. The primary outcome was recurrent IAI. Secondary outcomes included surgical site infections (SSIs), Clostridium difficile infections (CDIs), secondary fungal infections, and in-hospital mortality.

RESULTS

Forty-two patients met inclusion criteria and were divided into groups according to antimicrobial duration; 12 patients received <7 d, and 30 patients received >7 d of antibiotics. There were no differences in baseline characteristics between the two cohorts except for the presence of sepsis [4/12 (33.3%) versus 27/30 (90.0%); P = 0.001]. Thirty-one percent (13/42) of all organisms isolated from blood cultures were gram-negative bacteria, 12/42 (28.6%) were MDROs, and 2/42 (4.8%) patients experienced a culture mismatch in which cultured bacteria were not susceptible to empiric antibiotic therapy. Rates of recurrent IAI were similar between the two cohorts [1/12 (8.3%) versus 4/30 (13.3%), P = 0.554].

CONCLUSIONS

Among surgical ICU patients with BSI secondary to IAI, cessation of antibiotic therapy within 7 d of source control was not associated with an increased incidence of recurrent IAI.

Epidemiology and microbiology of Gram-negative bloodstream infections in a tertiary-care hospital in Beijing, China: a 9-year retrospective study

Background: Gram-negative bacterial bloodstream infections (BSIs) are associated with high morbidity and mortality. The present study examines the incidence, clinical characteristics, microbiological features, drug resistance and mortality associated with Gram-negative bacterial BSIs at a tertiary-care hospital in Beijing, China.Methods: This retrospective cohort study of patients with Gram-negative bacterial BSIs was performed between 1 January 2010 and 31 December 2018 at the Chinese People^,s Liberation Army General Hospital.Results: A total of 6867 episodes of Gram-negative bacterial BSIs occurred among 3199 patients over 9 years. The overall incidence of Gram-negative bacterial BSIs fluctuated from 2.30 to 2.55 episodes per 1000 admissions over 9 years. Escherichia coli was the major pathogen (34.3%). The antibiotic resistance of ESBLs-producing E. coli was higher than non-ESBLs producing E. coli including the majority of antibiotics, but to carbapenems (0.7% VS 5.1%). Between 2010 and 2018, the overall mortality of Gram-negative bacterial BSIs decreased from 11.41% to 9.05% (X² = 6.95, P = 0.434).Conclusions: Cephalosporins and carbapenem antibiotics were considered as the optimal treatment for patients with Gram-negative bacterial BSIs except for A. baumannii, which was treated according to the drug sensitivity or multidrug combination.

In-house protocol and performance of MALDI-TOF MS in the early diagnosis of bloodstream infections in a fourth-level hospital in Colombia: Jumping to full use of this technology

BACKGROUND

Bloodstream infections (BSIs) are a major cause of mortality in hospitalized patients. Rapid diagnosis is crucial because any delay in the antimicrobial treatment is associated with an increase in adverse patient outcomes. The application of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) technology directly to blood cultures permits earlier identification of BSIs and facilitates treatment management.

METHODS

A total of 470 positive blood cultures from patient samples were analyzed using Standard Aerobic/F and Anaerobic/F blood culture media. Isolates were identified using conventional identification methods and by the direct method using the MALDI-TOF MS system.

RESULTS

In 470 blood cultures, the direct method showed good identification results (420/470, 89%); specifically, accurate species and genus identification in 283/470 (60%), and only correct genus identification in 137/470 (29%). The direct protocol had better performance for Gram-negative compared to Gram-positive bacteria (97% vs 76%) and was unable to identify the positive blood cultures for both yeasts and some bacteria, mostly Gram-positive (50/470).

CONCLUSIONS

The protocol used here gave good and reliable results, being available up to 24 h earlier, while also leading to better use of MALDI-TOF.

In Vitro activity of a Novel Benzoquinolizine Antibiotic, Levonadifloxacin (WCK 771) against Blood Stream Gram-Positive Isolates from a Tertiary Care Hospital

Background  Blood stream infections (BSIs) due to Gram-positive pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) are associated with high mortality ranging from 10 to 60%. The current anti-MRSA agents have limitations with regards to safety and tolerability profile which limits their prolonged usage. Levonadifloxacin and its oral prodrug alalevonadifloxacin, a novel benzoquinolizine antibiotic, have recently been approved for acute bacterial skin and skin structure infections including diabetic foot infections and concurrent bacteremia in India.

Methods  The present study assessed the potency of levonadifloxacin, a novel benzoquinolizine antibiotic, against Gram-positive blood stream clinical isolates ( n = 31) collected from January to June 2019 at a tertiary care hospital in Mumbai, India. The susceptibility of isolates to antibacterial agents was defined following the Clinical and Laboratory Standard Institute interpretive criteria (M100 E29).

Results  High prevalence of MRSA (62.5%), quinolone-resistant Staphylococcus aureus (QRSA) (87.5%), and methicillin-resistant coagulase-negative staphylococci (MR-CoNS) (82.35%) were observed among bacteremic isolates. Levonadifloxacin demonstrated potent activity against MRSA, QRSA, and MR-CoNS strains with significantly lower minimum inhibitory concentration MIC _50/90 values of 0.5/1 mg/L as compared with levofloxacin (8/32 mg/L) and moxifloxacin (2/8 mg/L).

Conclusion  Potent bactericidal activity coupled with low MICs support usage of levonadifloxacin for the management of BSIs caused by multidrug resistant Gram-positive bacteria.

Evaluation of a mass spectrometry and Vitek 2 combined protocol for rapid identification and susceptibility testing of Enterobacterales directly from positive blood cultures

OBJECTIVE

The aim was to evaluate a rapid method which would combine identification and susceptibility testing directly from positive blood cultures for Gram-negative bacilli of the Enterobacterales.

MATERIAL AND METHODS

Gram-negative rods from blood cultures were directly identified by MALDI-TOF. Samples with Enterobacterales were selected for direct antimicrobial susceptibility testing by Vitek 2. The results were compared to those obtained with our laboratory's standard method.

RESULTS

MALDI-TOF directly from blood cultures identified correctly 83% of the samples. Enterobacterales (n=68) were identified at gender and species level in 85% of blood cultures with a score >1.7. In general, MICs were obtained after 7h. MICs of amoxicillin-clavulanate, amikacin and ciprofloxacin showed in almost 50% of the cases after 5h.

CONCLUSIONS

A simple procedure with low cost and reduced working time makes it possible to integrate both identification and susceptibility testing directly from blood cultures. Thus, this protocol could offer advantages when it comes to selection and cost of treatment and patients' clinical outcomes.

Antibiotic Resistant Bacterial Pathogens Associated with Blood Stream Infections and Urinary Tract Infections among Intensive Care Unit Patients

Blood Stream Infection (BSI) and Urinary Tract Infection (UTI) being leading causes of morbidity and mortality represent a common complication among critically ill patients. During the last decade, clinicians have observed a rising occurrence of BSIs due to bacterial resistance. Likewise, catheter-associated UTI is a main cause of morbidity and mortality affecting all age groups. Coliforms happen to be the prominent pathogens among our ICU admitted patients. It was alarming to notice 42.9% resistance to tigecycline among K. pneumoniae isolated from blood. K. pneumoniae isolates cultured from urine of ICU patients uniformly displayed 75% resistance to ciprofloxacin, ceftriaxone, cefoxitin and cefepime. Interestingly, it is of respite to observe 85.7% K. pneumoniae isolated from blood and 75% K. pneumoniae isolated from urine being susceptible to a conventional antibiotic, gentamicin. Escherichia coli isolated from urine were 100% susceptible to carbapenems and 91.75% were susceptible to tigecycline. Overall, 90% of Pseudomonas aeruginosa were susceptible to nitrofurantoin. The rapid spread of these MDR pathogens demands for national and regional guidelines. Policies to treat ICU related infections in UAE should be designed based on local microbiological data and resistance profiles of pathogens.

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.

Predictive factors for sepsis by carbapenem resistant Gram-negative bacilli in adult critical patients in Rio de Janeiro: a case-case-control design in a prospective cohort study

Background

Studies have investigated risk factors for infections by specific species of carbapenem-resistant Gram-negative bacilli (CR-GNB), but few considered the group of GNB species and most of them were performed in the setting of bacteremia or hospital infection. This study was implemented to identify risk factors for sepsis by CR- and carbapenem-susceptible (CS) GNB in intensive care unit (ICU) patients to improve management strategies for CR-GNB sepsis.

Methods

We developed a case-case-control study from a prospective cohort of patients with systemic inflammatory response syndrome (SIRS), sepsis-2 or sepsis-3 criteria in which blood and other sample cultures were collected and antimicrobial therapy was instituted, in an adult clinical-surgical ICU, at tertiary public hospital in Rio de Janeiro, from August 2015 through March 2017.

Results

Among the total of 629 ICU admissions followed by 7797 patient-days, after applying inclusion and exclusion criteria we identified 184 patients who developed recurrent or single hospital-acquired sepsis. More than 90% of all evaluable cases of sepsis and 87% of control group fulfilled the modified sepsis-3 definition. Non-fermenting bacilli and ventilator-associated pneumonia predominated as etiology and source of CR-GNB sepsis. While Enterobacteriaceae and intra-abdominal surgical site plus urinary-tract infections prevailed in CS-GNB than CR-GNB sepsis. Carbapenemase production was estimated in 76% of CR-GNB isolates. Multivariate logistic regression analysis revealed previous infection (mostly hospital-acquired bacterial infection or sepsis) (OR = 4.28; 95% CI 1.77–10.35), mechanical ventilation (OR = 4.21; 95% CI 1.17–15.18), carbapenem use (OR = 3.42; 95% CI 1.37–8.52) and length of hospital stay (OR = 1.03; 95% CI 1.01–1.05) as independent risk factors for sepsis by CR-GNB. While ICU readmission (OR = 6.92; 95% CI 1.72–27.78) and nosocomial diarrhea (OR = 5.32; 95% CI 1.07–26.45) were factors associated with CS-GNB sepsis.

Conclusions

The investigation of recurrent and not only bacteremic episodes of sepsis was the differential of this study. The results are in agreement with the basic information in the literature. This may help improve management strategies and future studies on sepsis by CR-GNB.

Guidelines of the Association of Anesthesiologists-Intensivists, the Interregional Non-Governmental Organization Alliance of Clinical Chemotherapists and Microbiologists, the Interregional Association for Clinical Microbiology and Antimicrobial Chemotherapy (IACMAC), and NGO Russian Sepsis Forum Diagnostics and antimicrobial therapy of the infections caused by multiresistant microorganisms

Introduction. Strains of microorganisms resistant to antimicrobial agents are commonly found in medical units throughout most regions of the world, including Russia. This leads to lower antimicrobial therapy efficacy when treating nosocomial infections. In this regard, the timely implementation of adequate antibiotic therapy is of great importance.

The objective of the guidelines: To provide summarized information on contemporary approaches to microbiological diagnostics and the assessment of results, as well as the principles of rational use of antimicrobial and antifungal agents, including treatment of infections caused by multiple drug-resistant strains of microorganisms.

Subjects and methods. These guidelines are based on published data obtained in the course of randomized trials, as well as information presented in the provisions of international guidelines supported by high-level evidence. The guidelines were prepared by a working group of Russian experts with extensive experience in research and practical work in this area. On October 11, 2019, the final version of the guidelines was reviewed and approved at a joint meeting of the working group and representatives of the public organizations which initiated the development of these guidelines (Association of Anesthesiologists-Intensivists, the Interregional Non-Governmental Organization Alliance of Clinical Chemotherapists and Microbiologists, the Interregional Association for Clinical Microbiology and Antimicrobial Chemotherapy (IACMAC), NGO Russian Sepsis Forum).

Conclusion. The guidelines reflect an interdisciplinary consensus of approaches to the diagnostics and antibiotic therapy of infections caused by multiresistant microorganisms. The provisions set forth should be used to decide on the strategy of empirical and etiotropic therapy of the most severe infections.

Follow-up blood cultures in Gram-negative bacilli bacteremia: are they needed for critically ill patients?

BACKGROUND

Gram-negative bacilli bacteremias (GNB-Bs) represent a major cause of morbidity and mortality in Intensive Care Unit (ICU) patients. Aim of this study was to investigate the role of follow-up blood cultures (FUBCs) and the clinical significance of persistent bacteremia (PB) in these settings.

METHODS

We retrospectively analyzed clinical data and outcome of GNB-Bs that occurred in ICU patients over a span of 1 year. In particular we sought information on development and clinical details of PB, defined as repeatedly positive FUBCs after ≥96 hours of appropriate antibiotic treatment and ≥48 hours after removal of endovascular devices.

RESULTS

Among 307 ICU patients, 69 (22.4%) developed 107 GNB-Bs. Of these, 78 (73%) could be eventually analyzed: 50 of 78 (64.1%) were non-PBs from 26 patients and 28 of 78 (35.9%) were PBs from 23 patients. Duration of fever and bacteremia, time to procalcitonin normalization and weaning from vasopressors were longer in episodes of PBs than non-PBs (P=0.04, P<0.001, P=0.02 and P=0.004, respectively). Primary bacteremia was more frequent in non-PBs than in PBs (29 of 50, 58% vs. 3/28, 10.7%, P=0.0001), whereas septic thrombus infection (STI) was the source of infection in 14 of 28 (50%). Finally, clinical features and 30-day mortality did not differ between patients with PB and those who developed only non-PB episodes.

CONCLUSIONS

Among our ICU patients, more than one third of GNB-Bs for which FUBCs were performed resulted PB. This condition is often associated with the presence of STI; therefore, FUBCs seem useful for the optimal management of GNB in this clinical setting.

Rapid multiplex detection of the resistance genes mecA, vanA and vanB from Gram-positive cocci-positive blood cultures using a PCR-dipstick technique

Introduction. Among the causative agents of bloodstream infections (BSIs), methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) are the key causative pathogens. Their rapid detection directly from Gram-positive cocci-positive blood culture specimens will promote timely treatment and help to implement effective infection control measures.Aim. We aim to develop a PCR-dipstick technique for the rapid detection of MRSA and VRE directly from positive blood culture specimens.Methodology. PCR-dipstick is a PCR-based multiplex detection technique where DNA-DNA hybridization is employed, and the results are interpreted with the naked eye. It was designed to target three drug resistance genes: mecA in MRSA and vanA/vanB in VRE from positive blood culture specimens. A total of 120 clinical isolates were used to evaluate the sensitivity and specificity of PCR-dipstick. Then, PCR-dipstick was examined for MRSA and VRE detection directly from positive blood cultures.Results. PCR-dipstick showed 100 % sensitivity and specificity in detecting mecA, vanA and vanB genes directly from bacterial colonies in comparison with multiplex PCR for genomic DNA followed by agarose gel electrophoresis. Further, it could differentially detect multiple resistant genes in pooled bacterial colonies (n=10). Ultimately, PCR-dipstick could detect MRSA and VRE in positive blood cultures in ~3 h.Conclusion. The results of the current study substantiate that PCR-dipstick can be used as an efficient detection system for MRSA and VRE directly from Gram-positive cocci-positive blood cultures. Its affordability and rapidity indicate that PCR-dipstick can be an effective tool for controlling nosocomial pathogens.

Novel Population Pharmacokinetic Model for Linezolid in Critically Ill Patients and Evaluation of the Adequacy of the Current Dosing Recommendation

Antimicrobial treatment in critically ill patients remains challenging. The aim of this study was to develop a population pharmacokinetic model for linezolid in critically ill patients and to evaluate the adequacy of current dosing recommendation (600 mg/12 h). Forty inpatients were included, 23 of whom were subjected to continuous renal replacement therapies (CRRT). Blood and effluent samples were drawn after linezolid administration at defined time points, and linezolid levels were measured. A population pharmacokinetic model was developed, using NONMEM 7.3. The percentage of patients that achieved the pharmacokinetic/pharmacodynamic (PK/PD) targets was calculated (AUC₂₄/MIC > 80 and 100% T_>MIC). A two-compartment model best described the pharmacokinetics of linezolid. Elimination was conditioned by the creatinine clearance and by the extra-corporeal clearance if the patient was subjected to CRRT. For most patients, the standard dose of linezolid did not cover infections caused by pathogens with MIC ≥ 2 mg/L. Continuous infusion may be an alternative, especially when renal function is preserved.

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.

Role of procalcitonin in predicting etiology in bacteremic patients: Report from a large single-center experience

BACKGROUND

Procalcitonin (PCT) is routinely used for an early recognition of severe infections and for promoting appropriate use of antibiotics. However, limited data correlating values of PCT with etiology of infection has been reported.

METHODS

During 2016, all positive blood cultures (BC) were retrospectively extracted in a 1100-beds Italian tertiary-care hospital. PCT and C-reactive protein (CRP) values were recorded within 24h from BC collection. Primary endpoint of the study was to investigate the correlation between PCT and CRP values and the occurrence of bloodstream infections (BSI) caused by bacteria or fungi.

RESULTS

During the study period, 1296 positive BC were included: 712 (54.9%) due to Gram-positive (GP), 525 (40.5%) due to Gram-negative (GN) strains, and 59 (4.6%) caused by fungi. Among GN isolates, enterobacteriaceae were reported in 453 (86.3%) cases. PCT values were higher in patients with GN etiology (26.1±14.2ng/mL) compared to GP (6.9±4.5) and fungi (3.3±2.4). Mean values for CRP in GN, GP, and fungi were not different. Receiver Operating Characteristic (ROC) curves showed an area under curve (AUC) of 0.71 for PCT and 0.51 for CRP among GN isolates; an AUC of 0.7 for PCT and 0.52 for CRP among enterobacteriaceae. Lower AUC for PCT were reported for GP and fungi.

CONCLUSIONS

PCT showed moderate performance in early detection (within 24h) of Gram-negative infections, especially those caused by enterobacteriaceae. Further prospective studies are mandatory to confirm these observations.