Antimicrobial management of sepsis and septic shock

Blood culture diagnostics: a Nordic multicentre survey comparison of practices in clinical microbiology laboratories

OBJECTIVES

Accurate and rapid microbiological diagnostics are crucial to tailor treatment and improve outcomes in patients with severe infections. This study aimed to assess blood culture diagnostics in the Nordic countries and to compare them with those of a previous survey conducted in Sweden in 2013.

METHODS

An online questionnaire was designed and distributed to the Nordic clinical microbiology laboratories (CMLs) (n = 76) in January 2018.

RESULTS

The response rate was 64% (49/76). Around-the-clock incubation of blood cultures (BCs) was supported in 82% of the CMLs (40/49), although in six of these access to the incubators around the clock was not given to all of the cabinets in the catchment area, and 41% of the sites (20/49) did not assist with satellite incubators. Almost half (49%, 24/49) of the CMLs offered opening hours for ≥10 h during weekdays, more commonly in CMLs with an annual output ≥30 000 BCs. Still, positive BCs were left unprocessed for 60-70% of the day due to restrictive opening hours. Treatment advice was given by 23% of CMLs (11/48) in ≥75% of the phone contacts. Rapid analyses (species identification and susceptibility testing with short incubation), performed on aliquots from positive cultures, were implemented in 18% of CMLs (9/49). Compared to 2013, species identification from subcultured colonies (<6 h) had become more common.

CONCLUSIONS

CMLs have taken action to improve aspects of BC diagnostics, implementing satellite incubators, rapid species identification and susceptibility testing. However, the limited opening hours and availability of clinical microbiologists are confining the advantages of these changes.

Early warning of bloodstream infection in elderly patients with circulating microparticles

Background

The difficulty of early diagnosis of bloodstream infection in the elderly patients leads to high mortality. Therefore, it is essential to determine some new methods of early warning of bloodstream infection in the elderly patients for timely adjustment of treatment and improvement of prognosis.

Methods

Patients aged over 65 years with suspected bloodstream infections were included and divided into bloodstream infection (BSI) and non-bloodstream infection (non-BSI) groups based on blood culture results. The morphology of microparticles (MPs) was observed by using transmission electron microscopy, and the number of MPs was dynamically monitored by flow cytometry.

Results

A total of 140 patients were included in the study: 54 in the BSI group and 86 in the non-BSI group. Total MPs (T-MPs) ≥ 6000 events/µL (OR, 7.693; 95% CI 2.944–20.103, P < 0.0001), neutrophil-derived MPs (NMPs) ≥ 500 events/µL (OR, 12.049; 95% CI 3.574–40.623, P < 0.0001), and monocyte counts ≤ 0.4 × 10⁹/L (OR, 3.637; 95% CI 1.415–9.348, P = 0.007) within 6 h of fever were independently associated with bloodstream infection in the elderly patients. We also developed an early warning model for bloodstream infection in the elderly patients with an area under the curve of 0.884 (95% CI 0.826–0.942, P < 0.0001), sensitivity of 86.8%, specificity of 76.5%, positive predictive value of 70.8%, and negative predictive value of 89.8%.

Conclusion

The early warning model of bloodstream infection based on circulating T-MPs, NMPs, and monocyte counts within 6 h of fever in the elderly patients was helpful in early detection of bloodstream infection and therefore promptly adjustment of treatment plan.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00901-w.

Efficient Early Diagnosis of Sepsis Using Whole-Blood PCR-Reverse Blot Hybridization Assay Depending on Serum Procalcitonin Levels

Sepsis is one of the medical emergencies, and its early detection, within the first hours of development, and proper management improve outcomes. Molecular diagnostic assays using whole blood collected from patients with suspected sepsis have been developed, but the decision making is difficult because of the possibility of false positives, due to contamination. Here, we evaluated the performance of the reverse blot hybridization assay (REBA) Sepsis-ID test for the detection of sepsis-causing microorganisms using whole-blood samples. In addition, the concentrations of C-reactive protein (CRP) and procalcitonin (PCT) were determined to evaluate whether these biomarkers can provide criteria for performing REBA Sepsis-ID in clinical settings. For this study, EDTA-anticoagulated whole blood was simultaneously collected for REBA Sepsis-ID and blood culture from 440 patients with suspected sepsis, from January to October 2015. In addition, CRP and PCT concentrations were measured in 227 patients. The overall positive rates of REBA Sepsis-ID and blood culture were 16.6% (73/440) and 13.9% (61/440), respectively. The pathogen-positive rates of REBA Sepsis-ID and blood culture were 9.8% (43/440) and 9.5% (42/440), respectively. The areas under the receiver operating characteristic (AUROC) curves of PCT and CRP for predicting pathogen-positive results of REBA Sepsis-ID were 0.72 and 0.69, respectively. The PCT concentrations in the group of patients aged ≥50 years were significantly higher than those in the group aged <50 years. After adjusting for age, the PCT AUROC value was 0.77 for predicting pathogen-positive results of REBA Sepsis-ID. The optimal cutoff values of PCT concentrations for subsequent application of REBA Sepsis-ID were 0.12 ng/mL in all patients and 0.22 ng/mL in patients aged ≥50 years. Our observations showed that REBA Sepsis-ID using whole blood was advantageous for the early detection of sepsis-causing microorganisms, and the PCT concentration could be used to determine the necessity of using REBA Sepsis-ID in clinical settings. The application of REBA Sepsis-ID using whole blood, based on the PCT concentration, may contribute to a highly efficient detection of sepsis-causing microorganisms.

The diagnostic roles of neutrophil in bloodstream infections

Bloodstream infections remain a leading cause of death worldwide, despite advances in critical care and understanding of the pathophysiology and treatment strategies. No specific biomarkers or therapy are available for these conditions. Neutrophils play a critical role in controlling infection and it is suggested that their migration and antimicrobial activity are impaired during sepsis which contribute to the dysregulation of immune responses. Recent studies further demonstrated that interruption or reversal of the impaired migration and antimicrobial function of neutrophils improves the outcome of sepsis in animal models. In this review, we provide an overview of the associated diagnostic biomarkers involved neutrophils in sepsis, and discuss the potential of neutrophils as a target to specifically predict the outcome of sepsis.

Quinolones for sepsis. A protocol for a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis

BACKGROUND

Sepsis is a relatively common and deadly condition that constitutes a major challenge to the modern health care system. Quinolones are sometimes used in combination with beta-lactam antibiotics for sepsis, but no former systematic review has assessed the benefits and harms of quinolones in patients with sepsis.

METHODS

We will perform a systematic review with meta-analysis and trial sequential analysis including randomised clinical trials assessing the effects of quinolones as add on therapy to usual care in children and adults with sepsis. For the assessment of harms, we will also include quasi-randomised studies and observational studies identified during our searches for randomised clinical trials.

DISCUSSION

This systematic review will clarify if there is evidence to support quinolones being part of the standard treatment for sepsis.

Rapid Diagnostics for Blood Cultures: Supporting Decisions for Antimicrobial Therapy and Value-Based Care

Bacteremia and sepsis are critically important syndromes with high mortality, morbidity, and associated costs. Bloodstream infections and sepsis are among the top causes of mortality in the US, with >600 deaths each day. Most septic patients can be found in emergency medicine departments or critical care units, settings in which rapid administration of targeted antibiotic therapy can reduce mortality. Unfortunately, routine blood cultures are not rapid enough to aid in the decision of therapeutic intervention at the onset of bacteremia. As a result, empiric, broad-spectrum treatment is common-a costly approach that may fail to target the correct microbe effectively, may inadvertently harm patients via antimicrobial toxicity, and may contribute to the evolution of drug-resistant microbes. To overcome these challenges, laboratorians must understand the complexity of diagnosing and treating septic patients, focus on creating algorithms that rapidly support decisions for targeted antibiotic therapy, and synergize with existing emergency department and critical care clinical practices put forth in the Surviving Sepsis Guidelines.

Diagnosis of sepsis from a drop of blood by measurement of spontaneous neutrophil motility in a microfluidic assay

Current methods for the diagnosis of sepsis have insufficient precision, causing regular misdiagnoses. Microbiological tests can help diagnose sepsis but are usually too slow to have an impact on timely clinical-decision making. Neutrophils have high sensitivity to infections, yet measurements of neutrophil surface markers, genomic changes, and phenotype alterations have had only a marginal effect on sepsis diagnosis. Here, we report a microfluidic assay that measures the spontaneous motility of neutrophils in the context of plasma, in one droplet of blood. We measured the performance of the assay in two independent cohorts of critically ill patients suspected of sepsis. In the first cohort, we developed a machine-learning-based scoring system (sepsis score) that segregated patients with sepsis from those without sepsis. In the second cohort, we validated the sepsis score in a double-blinded, prospective case-control study. For the 42 patients across the two cohorts, the assay identified sepsis patients with 97% sensitivity and 98% specificity. The neutrophil assay could potentially be used to accurately diagnose and monitor sepsis in larger populations of at-risk patients.

Bloodstream Infections

Bacteremia and sepsis are conditions associated with high mortality and are of great impact to health care operations. Among the top causes of mortality in the United States, these conditions cause over 600 fatalities each day. Empiric, broad-spectrum treatment is a common but often a costly approach that may fail to effectively target the correct microbe, may inadvertently harm patients via antimicrobial toxicity or downstream antimicrobial resistance. To meet the diagnostic challenges of bacteremia and sepsis, laboratories must understand the complexity of diagnosing and treating septic patients, in order to focus on creating algorithms that can help direct a more targeted approach to antimicrobial therapy and synergize with existing clinical practices defined in new Surviving Sepsis Guidelines. Significant advances have been made in improving blood culture media; as yet no molecular or antigen-based method has proven superior for the detection of bacteremia in terms of limit of detection. Several methods for rapid molecular identification of pathogens from blood cultures bottles are available and many more are on the diagnostic horizon. Ultimately, early intervention by molecular detection of bacteria and fungi directly from whole blood could provide the most patient benefit and contribute to tailored antibiotic coverage of the patient early on in the course of the disease. Although blood cultures remain as the best means of diagnosing bacteremia and candidemia, complementary testing with antigen tests, microbiologic investigations from other body sites, and histopathology can often aid in the diagnosis of disseminated disease, and application of emerging nucleic acid test methods and other new technology may greatly impact our ability to bacteremic and septic patients, particularly those who are immunocompromised.

Pediatric patients who receive antibiotics for fever and neutropenia in less than 60 min have decreased intensive care needs

BACKGROUND

Antibiotic delivery to patients with fever and neutropenia (F&N) in <60 min is an increasingly important quality measure for oncology centers, but several published reports indicate that a time to antibiotic delivery (TTA) of <60 min is quite difficult to achieve. Here we report a quality improvement (QI) effort that sought to decrease TTA and assess associated clinical outcomes in pediatric patients with cancer and F&N.

PROCEDURE

We used Lean-Methodology and a Plan-Do-Study-Act approach to direct QI efforts and prospectively tracked TTA measures and associated clinical outcomes (length of stay, duration of fever, use of imaging studies to search for occult infection, bacteremia, intensive care unit (ICU) consultation or admission, and mortality). We then performed statistical analysis to determine the impact of our QI interventions on total TTA, sub-process times, and clinical outcomes.

RESULTS

Our QI interventions significantly improved TTA such that we are now able to deliver antibiotics in <60 min nearly 100% of the time. All TTA sub-process times also improved. Moreover, achieving TTA <60 min significantly reduced the need for ICU consultation or admission (P = 0.003) in this population.

CONCLUSION

Here we describe our QI effort along with a detailed assessment of several associated clinical outcomes. These data indicate that decreasing TTA to <60 min is achievable and associated with improved outcomes in pediatric patients with cancer and F&N.

Added value of multi-pathogen probe-based real-time PCR SeptiFast in the rapid diagnosis of bloodstream infections in patients with bacteraemia

The commercial multi-pathogen probe-based real-time PCR SeptiFast (SF) was evaluated as a rapid and complementing tool for the microbiological diagnosis of bloodstream infections (BSIs) in a series of 138 matched blood samples from 65 patients with bacteraemia, hospitalized in an intensive care unit, when antibiotics had already been administered. SF was positive in 32.6 % of the samples, whereas blood culture (BC) was positive in 21.7 % (P < 0.05). SF identified more pathogens (11 versus 5; specificity, 90.7 %) and reduced the time of aetiological diagnosis, with a mean of 16.3 versus 55.4 h needed for BC (P < 0.05). SF enabled appropriate pathogen-oriented therapy in 72 % (36/50) of the BSI group of patients on the basis of epidemiological data. According to our data, the use of SF provided important added value to BC, in terms of earlier aetiological diagnosis of BSIs, enabling pathogen-oriented therapy in patients receiving empirical antibiotic treatment.

Characteristics of surgical patients receiving inappropriate empiric antimicrobial therapy

BACKGROUND

Inappropriate antibiotics have been observed to result in an increased duration of antibiotic treatment and hospital length of stay, development of multidrug-resistant organisms, and mortality rate compared with appropriate antibiotic treatment. Few studies have evaluated independent risk factors associated with inappropriateness. The purpose of this study was to identify independent predictors of inappropriate, empiric antimicrobial therapy for the treatment of severe sepsis.

METHODS

This was a retrospective analysis of a prospectively maintained database of all surgical/trauma patients admitted to a tertiary care center from 1996 to 2007 and treated for sepsis. "Appropriate" empiric antibiotic treatment was determined by sensitivity testing. Demographics and comorbidities, infection sites, infection organisms, and outcomes between strata were compared. Differences in outcome were estimated using relative risk and 95% confidence intervals for correlated data.

RESULTS

A total of 2,855 patients (7,158 infections) were identified. Independent predictors of inappropriate, empiric antimicrobial therapy for the treatment of severe sepsis included site of infection and organism type. Severity of illness, age, medical conditions, and community versus health care-associated infections were not associated with inappropriate therapy. Although inappropriate empiric therapy was associated with a longer length of stay and duration of antimicrobial use, it did not result in higher mortality.

CONCLUSION

Our study observed that inappropriate empiric antibiotic selection is related to site of infection and pathogen. Other clinical variables do not appear to predict inappropriateness of antibiotic treatment. Efforts should be focused on early broad-spectrum therapy and more rapid microbiologic methods.

LEVEL OF EVIDENCE

Therapeutic/care management study, level II.

Combination of conventional blood cultures and the SeptiFast molecular test in patients with suspected sepsis for the identification of bloodstream pathogens

We evaluated performances of the molecular test SeptiFast (SF) for the detection of agents of bloodstream infection (BSI) in patients with suspected sepsis, the majority of them under antibiotic treatment and at high prevalence of HIV-1 infection (10.5%). Matched SF and blood culture (BC) samples (n=1186) from 1024 patients were studied. Two hundred fifty-one episodes of BSI out of 1144 were identified with the combined methods (22%). SF identified more episodes of BSI than BC: 206 versus 176 (χ(2)=7.008, P=0.0081) and a significantly higher number of Gram-negative bacteria than BC (77 versus 53, χ(2)=9.12; P=0.0025), as well as of polymicrobial infections (χ(2)=4.50, P=0.0339). In conclusion, SF combined with BC improved the diagnosis of sepsis, especially in immunocompromised patients.

The meta-genome of sepsis: host genetics, pathogens and the acute immune response

Severe infection and the patient response constitute sepsis. Here, we review the meta-genome (patient genetics, pathogen communities and host response) and its impact upon the outcome of severe sepsis. Patient genetics, both predisposition for infection and the subsequent response to infection are reviewed. The pathogen is discussed with particular emphasis upon the modern era of microbiome analysis and nucleic acid diagnostics. Finally, we discuss the host clinical and immune responses and present new data to suggest that the immune response is the key to understanding sepsis and improving a death rate of nearly 30%.

Fever and the rational use of antimicrobials in the emergency department

Any patient presenting to the emergency department (ED) with fever triggers consideration of the administration of an antimicrobial. Empiric antimicrobial therapy has become a cornerstone of treatment. Frequently, the decision to initiate empiric treatment needs to be made before the definitive diagnosis is known. In such cases, an organized approach is helpful. This article aims to provide a systems-based approach to prescribing antimicrobials to patients presenting to the ED with fever, while understanding the risk associated with overutilization. An understanding of the key considerations is needed to ensure that decisions are made well and appropriate treatment begins promptly.

Invasive candidiasis in intensive care units in China: a multicentre prospective observational study

OBJECTIVES

To describe the epidemiology, microbiology and management of invasive Candida infection (ICI) in intensive care units (ICUs) in China.

METHODS

A multicentre, prospective, observational study in 67 hospital ICUs across China. Patients were ≥18 years old with clinical signs of infection and at least one of the following diagnostic criteria: (i) histopathological, cytopathological or microscopic confirmation of yeast cells from a normally sterile site; (ii) at least one peripheral blood culture positive for Candida; and (iii) positive Candida culture from a normally sterile site. The China-SCAN study is registered with ClinicalTrials.gov (NCT T01253954).

RESULTS

ICI incidence was 0.32% (306 patients/96,060 ICU admissions) and median time between ICU admission and diagnosis was 10.0 days. Candida albicans was the most prevalent single isolate (41.8% of patients), although non-albicans species accounted for the majority of infections. Diagnostic confirmation was based solely on at least one positive blood culture in 290 (94.8%) cases. Treatment was initiated after diagnostic confirmation in 166/268 (61.9%) patients. Triazoles (62.7%) and echinocandins (34.2%) were the most commonly used antifungal agents; first-line therapy was typically fluconazole (37.7%). The median duration of antifungal therapy was 14 days. The mortality rate was 36.6% (112/306); the median time between diagnosis and death was 14.5 days. Mortality was higher in older individuals, those with solid tumours, those with recent invasive mechanical ventilation and those with a higher sequential organ failure assessment score at diagnostic confirmation. Susceptibility to first-line antifungals was associated with lower mortality than dose-dependent susceptibility or complete resistance (P=0.008).

CONCLUSIONS

More infections were caused by non-albicans than Candida albicans strains. The majority of patients were treated only after diagnostic confirmation, rather than empirically. First-line antifungal susceptibility was associated with lower mortality.

Time to effective antibiotic administration in adult patients with septic shock: a descriptive analysis

OBJECTIVE

To determine the median time to antibiotic administration following the onset of septic shock at our institution as well as the appropriateness of empiric therapy, sources of delay in antibiotic administration and the effect of delays on survival.

RESEARCH METHODOLOGY

Retrospective health record review of 55 patients with septic shock admitted to the intensive care unit (ICU) between July 1, 2008 and December 31, 2009.

SETTING

Nine-bed adult medical-surgical ICU within a 300-bed community acute care hospital.

MAIN OUTCOME MEASURES

Median time to antibiotic administration, appropriateness of empiric therapy, sources of delay in antibiotic administration.

RESULTS

The median (min,max) time to the initiation of antibiotics was determined to be 1.7 (0,31) hours. Only 34% (19/55) of patients received antibiotics within the recommended one hour. Empiric antibiotic therapy was determined to be appropriate in 91% (50/55) of patients. The median (min,max) time to administration of effective antibiotic therapy tended to be faster in the emergency room [1.1 (0,16) hours] compared to the ICU [2.3 (0,13)].

CONCLUSION

The median time to antibiotic administration at our institution following the onset of septic shock was longer than the evidence-based guideline recommendations of within one hour.

Early and adequate antibiotic therapy in the treatment of severe sepsis and septic shock

Severe sepsis and septic shock are conditions that pose difficult challenges to physicians and the health care system. In the past 10 years, a number of retrospective and prospective observational studies have shed light on the importance of a rapid and systematic approach to treatment of these conditions. A key component is early and appropriate use of antibiotics. Delay of even 6 h can dramatically increase hospital mortality. In addition, multivariate analyses have demonstrated that inappropriate initial antibiotics lead to worse outcomes. The treating physician can rapidly identify risk factors for initial inappropriate antibiotics at the bedside, such as recent antibiotic therapy or recent hospitalization. Organized antibiotic order sets have been shown to significantly improve timely appropriate antibiotic administration in septic patients. Finally, emerging laboratory data suggest that early in the course of septic shock, the pharmacokinetics of common broad spectrum antibiotics may be significantly altered due to increased volumes of distribution having dosing implications for antibiotics in septic shock.

Microbiology and antibiotic susceptibility of organisms in bile cultures from patients with and without cholangitis at an Asian academic medical center

PURPOSE

To review the epidemiology of microbial isolates from bile cultures taken from patients with and without cholangitis admitted to an Asian academic medical center in order to compare antimicrobial sensitivities and to make recommendations for empiric antimicrobial therapy of patients with cholangitis in the Philippines.

METHODS

Routine aerobic bile culture results and corresponding clinical abstracts of surgical patients admitted to an academic medical center over a three-year period were analyzed.

RESULTS

The series consisted of 125 patients, 77 with cholangitis (62%) and 48 (38%) without, which was determined according to the Tokyo Guidelines. Patients with cholangitis were significantly more likely to have positive bile cultures (p = 0.012). Gram-negative bacilli were the most common isolates in both patients with (94%) and patients without (95%) cholangitis. For both groups, Escherichia coli (36%) had greatest sensitivity to amikacin, cefepime, ceftriaxone, gentamicin, imipenem-cilastatin meropenem, and piperacillin-tazobactam; Klebsiella pneumoniae (16%) had greatest sensitivity to amikacin, cefepime, ceftriaxone, gentamicin, imipenem-cilastatin meropenem, and piperacillin-tazobactam; and Pseudomonas aeruginosa (12.5%) was most sensitive to cefepime, gentamicin, imipenem-cilastatin meropenem, and piperacillin-tazobactam.

CONCLUSIONS

Gram-negative bacilli (or Enterobacteriaceae) (E. coli, K. pneumoniae, P. aeruginosa, and Enterobacter cloacae) were the most common aerobic microbial isolates in bile cultures from patients with cholangitis in the Philippines. Their antimicrobial susceptibility patterns suggest that imipenem-cilastatin (sensitivity 100%), meropenem (100%), amikacin (90-100%), cefepime (75%-100%), ceftriaxone (75%-100%), gentamicin (67%-100%), and piperacillin-tazobactam (50%-100%) would be the most effective antimicrobials for both groups. However, the authors echo the caution from the Surgical Infection Society/Infectious Diseases Society of America against using aminoglycosides as empiric drugs when safer and equally effective regimens are available.

Interpreting culture and susceptibility data in critical care: perks and pitfalls

PROBLEM

The need for immediate, effective antimicrobial therapy in the critical care patient must be tempered by approaches which simultaneously minimize emergence of antimicrobial resistance. Ideally, therapy will successfully resolve clinical signs of infection, while eradicating infecting pathogens such that the risk of resistance is avoided. Increasing limitations associated with empirical antimicrobial choices direct the need for culture and susceptibility data as a basis of therapy. Even so, such in vitro data should be utilized within its limitations.

OBJECTIVES

To demonstrate the attributes and limitations of patient and population culture and susceptibility (pharmacodynamic) data in the selection of antimicrobial drugs and to demonstrate the design of individualized dosing regimens based on integration of pharmacodynamic (PD) and pharmacokinetic (PK) data.

DIAGNOSIS

Limitations in culture and susceptibility testing begin with sample collection and continue through drug selection and dose design. Among the challenges in interpretation is discrimination between pathogens and commensals. Properly collected samples are critical for generation of data relevant to the patient's infection. Data are presented as minimum inhibitory concentrations (MICs). The MIC facilitate selection of the most appropriate drug, particularly when considered in the context of antimicrobial concentrations achieved in the patient at a chosen dose. Integration of MIC data with key PK data yields the C(max):MIC important to efficacy of concentration-dependent drugs and T>MIC, which guides use of time-dependent drugs. These indices are then used to design dosing regimens that are more likely to kill all infecting pathogens. In the absence of patient MIC data, population data (eg, MIC(90)) may serve as a reasonable surrogate.

CONCLUSIONS

Properly collected, performed, and interpreted culture and susceptibility data are increasingly important in the selection of and design of dosing regimens for antimicrobial drugs. Integration of PK and PD data as modified by host and microbial factors supports a hit hard, exit fast approach to therapy that will facilitate efficacy while minimizing resistance.