Diagnóstico microbiológico de la bacteriemia y la fungemia: hemocultivos y métodos moleculares

Clinical significance of inflammatory markers for evaluating disease severity of mixed-pathogen bloodstream infections of both Enterococcus spp. and Candida spp

Objective

In recent decades, there has been a notable increase in the morbidity and mortality rates linked to bacteremia and candidemia. This study aimed to investigate the clinical significance of inflammatory markers in assessing the disease severity in critically ill patients suffering from mixed-bloodstream infections (BSIs) due to Enterococcus spp. and Candida spp.

Methods

In this retrospective research, patients diagnosed with BSIs who were admitted to the intensive care unit (ICU) during the period of January 2019 to December 2022 were analyzed. The patients were divided into two groups: a mixed-pathogen BSI group with both Enterococcus spp. and Candida spp., and a single-pathogen BSI group with only Enterococcus spp. The study examined the differences in inflammatory marker levels and disease severity, including Acute Physiology and Chronic Health Evaluation (APACHE) II scores, duration of ICU stay, and 30-day mortality, between the two groups. Furthermore, we sought to scrutinize the potential associations among these aforementioned parameters.

Results

The neutrophil-to-lymphocyte ratios (NLRs) and levels of plasma C-reactive protein (CRP), interleukin (IL)-6, IL-8, and tumor necrosis factor-α (TNF-α) in the mixed-pathogen BSI group were higher than those in the single-pathogen BSI group. Spearman's rank correlation analysis showed that NLRs and plasma CRP and IL-6 levels were positively correlated with disease severity in the mixed-pathogen BSI group. Further, the levels of plasma IL-8 and TNF-α were also positively correlated with ICU stay duration and 30-day mortality. In multivariate analysis, plasma CRP and IL-6 levels were independently associated with 30-day mortality.

Conclusion

Mixed-pathogen BSIs caused by Enterococcus spp. and Candida spp. may give rise to increased NLRs and plasma CRP, IL-6, IL-8, and TNF-α levels in comparison to BSI caused by Enterococcus spp. only, thus leading to elevated disease severity in critically ill patients.

Antibiotic use and outcome in patients with negative blood cultures, a new target population for antimicrobial stewardship interventions: A prospective multicentre cohort (NO-BACT)

OBJECTIVES

To evaluate the appropriateness of antimicrobial treatment and the risk factors for mortality in patients with negative blood cultures (BC), in order to evaluate whether this population would be a suitable target for antimicrobial stewardship (AMS) interventions.

METHODS

A multicentre prospective cohort study of patients with negative BC in three Spanish hospitals between October 2018 and July 2019 was performed. The main endpoints were the appropriateness of antimicrobial treatment (evaluated by two investigators according to local guidelines) and 30-day mortality. Cox-regression was performed to estimate the association between variables and 30-day mortality.

RESULTS

Of 1011 patients in whom BC was obtained, these were negative in 803 (79%) and were included; 30-day mortality was 9% (70 patients); antibiotic treatment was considered inappropriate in 299 (40%) of 747 patients evaluated at day 2, and in 266 (46%) of 573 at day 5-7. The variables independently associated with increased risk of 30-day mortality were higher age (HR 1.05; 95% CI 1.03-1.07), neoplasia (HR 2.73; 95% CI 1.64-4.56), antibiotic treatment in the 48 h prior to BC extraction (HR 2.06; 95% CI 1.23-3.43) and insufficient antibiotic coverage at day 2 after BC obtainment (HR 2.35; 95% CI 1.39-4.00). Urinary, catheter and biliary sources of infection were associated with lower risk (HR 0.40; 95% CI 0.20-0.81).

CONCLUSIONS

Antimicrobial treatment is frequently inappropriate among patients with negative BC; insufficient antibiotic coverage at day 2 was associated with mortality. These results suggest that patients with negative BC are a suitable population for AS interventions.

SUMMARY

Antimicrobial treatment in patients with negative blood culture was frequently inappropriate, and inappropriate coverage at day 2 was associated with increased risk of death. These data support the consideration of this population as a potential target for antimicrobial stewardship interventions.

Ultrafast detection of β-lactamase resistance in Klebsiella pneumoniae from blood culture by nanopore sequencing

Aim: This study aimed to assess the ultra-fast method using MinION™ sequencing for rapid identification of β-lactamase-producing Klebsiella pneumoniae clinical isolates from positive blood cultures. Methods: Spiked-blood positive blood cultures were extracted using the ultra-fast method and automated DNA extraction for MinION sequencing. Raw reads were analyzed for β-lactamase resistance genes. Multilocus sequence typing and β-lactamase variant characterization were performed after assembly. Results: The ultra-fast method identified clinically relevant β-lactamase resistance genes in less than 1 h. Multilocus sequence typing and β-lactamase variant characterization required 3-6 h. Sequencing quality showed no direct correlation with pore number or DNA concentration. Conclusion: Nanopore sequencing, specifically the ultra-fast method, is promising for the rapid diagnosis of bloodstream infections, facilitating timely identification of multidrug-resistant bacteria in clinical samples.

Usefulness of the 5MPB-Toledo model to predict bacteremia in patients with urinary tract infections in the emergency department

OBJECTIVE

To analyze the usefulness of a new predictive model of bacteremia (5MPB-Toledo) in patients treated for urinary tract infection (UTI) in the emergency department (ED).

METHODS

Prospective and multicenter observational cohort study of the blood cultures (BC) ordered for patients with UTIs in 65 Spanish ED from November 1, 2019, to March 31, 2020. The predictive ability of the model was analyzed with the area under the Receiver Operating Characteristic curve (AUC-ROC). The diagnostic performance was calculated with the chosen cut-off point for sensitivity, specificity, positive predictive value, and negative predictive value.

RESULTS

A total of 1,499 blood cultures were evaluated. True cases of bacteremia were confirmed in 277 (18.5%). The remaining 1,222 cultures (81.5%) were negative. Ninety-four (6.3%) were considered contaminated. The model's area under the ROC curve was 0.937 (95% CI, 0.926-0.949). The prognostic performance with a model's cut-off value of ≥5 points achieved 97.47% (95% CI, 94.64-98.89) sensitivity, 76.68% (95% CI, 74.18-79.00) specificity, 48.65% (95% CI, 44.42-52.89) positive predictive value and 99.26% (95% CI, 98.41-99.67) negative predictive value.

CONCLUSION

The 5MPB-Toledo score is useful for predicting bacteremia in patients with UTIs who visit the ED.

Risk factors for ophthalmologic involvement and ocular findings in patients diagnosed with fungemia in a high-complexity hospital in the city of Medellín, Colombia

PURPOSE

To describe the demographic clinical characteristics and to identify the risk factors of patients diagnosed with fungemia and secondary intraocular involvement.

METHODS

Retrospective cohort of 97 patients diagnosed with fungemia and with or without involvement of the posterior segment. Demographic, clinical and ophthalmological variables were identified to establish the risk of retinal seeding.

RESULTS

An incidence of ocular involvement of 22.68% was obtained and no clear risk factor was found for subsequent showings in patients with fungemia. A risk trend was only found in patients with diabetes with an OR: 2.85; CI 95%: (0.80-10.12) and history of HIV with an OR: 2.29 CI95%: (0.85-6.12).

CONCLUSIONS

In this first cohort carried out in Colombia according to our search, findings were obtained that agree with those of other authors worldwide, where there is no evidence of a decrease in incidence compared with older studies and the absence of risk factors for the compromise of the posterior pole in patients with fungemia.KEY MESSAGESSystematic fundus evaluation by an ophthalmologist in patients with candidaemia is a recommended practice based on low-quality evidence.The identification of real risk factors for retinal compromise in fungemia would allow us to be more selective with the population to be evaluated.Fungemia generally occurs in critically ill patients, where access and availability of ophthalmology evaluation are a resource that is not always available.

Validation of a predictive model for bacteraemia (MPB5-Toledo) in the patients seen in emergency departments due to infections

OBJECTIVE

To validate a simple risk score to predict bacteremia (MPB5-Toledo) in patients seen in the emergency departments (ED) due to infections.

METHODS

Prospective and multicenter observational cohort study of the blood cultures (BC) ordered in 74 Spanish ED for adults (aged 18 or older) seen from October 1, 2019, to February 29, 2020. The predictive ability of the model was analyzed with the area under the Receiver Operating Characteristic curve (AUC-ROC). The prognostic performance for true bacteremia was calculated with the cut-off values chosen for getting the sensitivity, specificity, positive predictive value and negative predictive value.

RESULTS

A total of 3.843 blood samples wered cultured. True cases of bacteremia were confirmed in 839 (21.83%). The remaining 3.004 cultures (78.17%) were negative. Among the negative, 172 (4.47%) were judged to be contaminated. Low risk for bacteremia was indicated by a score of 0-2 points, intermediate risk by 3-5 points, and high risk by 6-8 points. Bacteremia in these 3 risk groups was predicted for 1.5%, 16.8%, and 81.6%, respectively. The model's area under the receiver operating characteristic curve was 0.930 (95% CI, 0.916-0.948). The prognostic performance with a model's cut-off value of ≥5 points achieved 94.76% (95% CI: 92.97-96.12) sensitivity, 81.56% (95% CI: 80.11-82.92) specificity, and negative predictive value of 98.24% (95% CI: 97.62-98.70).

CONCLUSION

The 5MPB-Toledo score is useful for predicting bacteremia in patients attended in hospital emergency departments for infection.

Blood culture-negative infective endocarditis: a worse outcome? Results from a large multicentre retrospective Spanish cohort study

BACKGROUND

To assess the impact of blood cultures negative infective endocarditis (BCNIE) on in-hospital mortality.

METHODS

Prospective multicentre study with retrospective analysis of a Spanish cohort including adult patients with definite IE. Cardiac implantable devices infection were excluded. Comparisons between blood cultures positive and BCNIE groups were performed to analyse in-hospital mortality.

RESULTS

1001 cases were included of which 83 (8.3%) had BCNIE. Alternative microbiological diagnosis was achieved for 39 (47%) out 83 cases. The most frequent identifications were: Coxiella burnetii (11; 28.2%), Tropheryma whipplei (4; 10.3%), Streptococcus gallolyticus (4;10.3%) and Staphylococcus epidermidis (3; 7.7%). Surgery was performed more frequently in BCNIE group (57.8 vs. 36.9%, p < .001). All-cause in-hospital mortality rate was 26.7% without statistical difference between compared groups. BCNIE was not associated to worse mortality rate in Cox regression model (aHR = 1.37, 95% CI 0.90-2.07, p = .14). Absence of microbiological diagnosis was also not associated to worse in-hospital prognosis (aHR = 1.62, 95% CI 0.99-2.64, p = .06).

CONCLUSIONS

In our cohort, BCNIE was not associated to greater in-hospital mortality based in multivariate Cox regression models. The variables most frequently associated with mortality were indicated but not performed surgery (aHR = 2.48, 95% CI 1.73-3.56, p < .001), septic shock (aHR = 2.24, 95% CI 1.68-2.99, p < .001), age over 65 years (aHR = 1.88, 95% CI 1.40-2.52, p < .001) and complicated endocarditis (aHR = 1.79, 95% CI 1.36-2.37, p < .001).

A bacteraemia risk prediction model: development and validation in an emergency medicine population

OBJECTIVE

Design a risk model to predict bacteraemia in patients attended in emergency departments (ED) for an episode of infection.

METHODS

This was a national, prospective, multicentre, observational cohort study of blood cultures (BC) collected from adult patients (≥ 18 years) attended in 71 Spanish EDs from October 1 2019 to March 31, 2020. Variables with a p value < 0.05 were introduced in the univariate analysis together with those of clinical significance. The final selection of variables for the scoring scale was made by logistic regression with selection by introduction. The results obtained were internally validated by dividing the sample in a derivation and a validation cohort.

RESULTS

A total of 4,439 infectious episodes were included. Of these, 899 (20.25%) were considered as true bacteraemia. A predictive model for bacteraemia was defined with seven variables according to the Bacteraemia Prediction Model of the INFURG-SEMES group (MPB-INFURG-SEMES). The model achieved an area under the curve-receiver operating curve of 0.924 (CI 95%:0.914-0.934) in the derivation cohort, and 0.926 (CI 95%: 0.910-0.942) in the validation cohort. Patients were then split into ten risk categories, and had the following rates of risk: 0.2%(0 points), 0.4%(1 point), 0.9%(2 points), 1.8%(3 points), 4.7%(4 points), 19.1% (5 points), 39.1% (6 points), 56.8% (7 points), 71.1% (8 points), 82.7% (9 points) and 90.1% (10 points). Findings were similar in the validation cohort. The cut-off point of five points provided the best precision with a sensitivity of 95.94%, specificity of 76.28%, positive predictive value of 53.63% and negative predictive value of 98.50%.

CONCLUSION

The MPB-INFURG-SEMES model may be useful for the stratification of risk of bacteraemia in adult patients with infection in EDs, together with clinical judgement and other variables independent of the process and the patient.

[Usefulness of the 5MPB-Toledo model to predict bacteremia in patients with community-acquired pneumonia in the Emergency Department]

OBJECTIVE

To analyse a new risk score to predict bacteremia in the patients with Community-acquired Pneumonia (CAP) in the emergency departments.

METHODS

Prospective and multicenter observational cohort study of the blood cultures ordered in 74 Spanish emergency departments for patients with CAP seen from November 1, 2019, to March 31, 2020. The predictive ability of the model was analyzed with the area under the Receiver Operating Characteristic curve (AUC-ROC). The prognostic performance for true bacteremia was calculated with the chosen cut-off for getting the sensitivity, specificity, positive predictive value and negative predictive value.

RESULTS

A total of 1,020 blood samples wered cultured. True cases of bacteremia were confirmed in 162 (15.9%). The remaining 858 cultures (84.1%) wered negative. And, 59 (5.8%) were judged to be contaminated. The model´s area under the receiver operating characteristic curve was 0.915 (95% CI, 0.898-0.933). The prognostic performance with a model´s cut-off value of ≥ 5 points achieved 97.5% (95% CI, 95.1-99.9) sensitivity, 73.2% (95% CI, 70.2-76.2) specificity, 40.9% (95% CI, 36.4-45.1) positive predictive value and 99.4% (95% CI, 99.1-99.8) negative predictive value.

CONCLUSIONS

The 5MPB-Toledo score is useful for predicting bacteremia in the patients with CAP seen in the emergency departments.

Validation of a predictive model for bacteraemia (MPB5-Toledo) in the patients seen in emergency departments due to infections

OBJECTIVE

To validate a simple risk score to predict bacteremia (MPB5-Toledo) in patients seen in the emergency departments (ED) due to infections.

METHODS

Prospective and multicenter observational cohort study of the blood cultures (BC) ordered in 74 Spanish ED for adults (aged 18 or older) seen from from October 1, 2019, to February 29, 2020. The predictive ability of the model was analyzed with the area under the Receiver Operating Characteristic curve (AUC-ROC). The prognostic performance for true bacteremia was calculated with the cut-off values chosen for getting the sensitivity, specificity, positive predictive value and negative predictive value.

RESULTS

A total of 3.843 blood samples wered cultured. True cases of bacteremia were confirmed in 839 (21.83%). The remaining 3.004 cultures (78.17%) were negative. Among the negative, 172 (4.47%) were judged to be contaminated. Low risk for bacteremia was indicated by a score of 0 to 2 points, intermediate risk by 3 to 5 points, and high risk by 6 to 8 points. Bacteremia in these 3 risk groups was predicted for 1.5%, 16.8%, and 81.6%, respectively. The model's area under the receiver operating characteristic curve was 0.930 (95% CI, 0.916-0.948). The prognostic performance with a model's cut-off value of ≥ 5 points achieved 94.76% (95% CI: 92.97-96.12) sensitivity, 81.56% (95% CI: 80.11-82.92) specificity, and negative predictive value of 98.24% (95% CI: 97.62-98.70).

CONCLUSION

The 5MPB-Toledo score is useful for predicting bacteremia in patients attended in hospital emergency departments for infection.

Incidence of Bacteremia Consequent to Different Endoscopic Procedures in Dogs: A Preliminary Study

Endoscopic procedures are widely used in veterinary medicine, and their role in producing transient bacteremia is debatable. The growing issue of antibiotic resistance requires the correct use of antibiotics, avoiding their administration when not strictly necessary. Studies highlighting post-endoscopy bacteremia in veterinary medicine are extremely rare and often involve very few animals. This study describes the results from 74 owned dogs, brought to the Veterinary Teaching Hospital of the Department of Veterinary Medical Science of the University of Bologna, for the purpose of undergoing an endoscopic procedure. Two blood samples were taken from each dog, one before and one after the procedure, in order to assess the incidence of bacteremia linked to endoscopic procedures. Eight dogs were tested positive at the second blood culture with an Incidence Risk (IR) of 10.8%. No statistical differences were found by comparing positive and negative blood cultures with respect to sex, age, weight and anesthesia duration. In addition, no difference was found between airway and digestive tract procedures. The present findings showed that the probability of developing bacteremia after an endoscopic procedure was quite low, and additional studies confirming this are certainly recommended as well as the evaluation of categories of patients potentially considered at risk.

[Predictive factors of bacteraemia in the patients seen in emergency departments due to infections]

Objetivos

Analizar los factores predictivos de bacteriemia en los pacientes atendidos en el servicio de urgencias (SU) por un episodio de infección.

Pacientes y métodos

Estudio observacional, retrospectivo, descriptivo y analítico de todos los hemocultivos extraídos en un SU en los pacientes adultos (≥ 18 años) atendidos por infección desde el 1-1-2018 hasta el 1-7-2018. Se realizó seguimiento durante 30 días. Se analizaron 38 variables independientes (epidemiológicas, de comorbilidad, funcionales, clínicas y analíticas) que pudieran predecir la existencia de bacteriemia. Se realizó un estudio univariado y multivariante mediante regresión logística.

Resultados

Se incluyeron 1.425 episodios de hemocultivos extraídos. De ellos se consideraron como bacteriemias verdaderas 179 (12,6 %) y como HC negativos 1.246 (87,4 %). Entre los negativos, 1.130 (79,3%) no tuvieron crecimiento y 116 (8,1%) se consideraron contaminados. Cinco variables se asociaron de forma significativa como predictoras de bacteriemia verdadera: procalcitonina (PCT) sérica ≥ 0,51 ng/ml [odds ratio (OR): 4,52; intervalo de confianza (IC) al 95%: 4,20-4,84; p <0,001], temperatura > 38,3°C [OR: 1,60; IC al 95%: 1,29-1,90; p <0,001], presión arterial sistólica (PAS) < 100 mmHg [OR: 3,68; IC al 95%: 2,78-4,58; p <0,001], shock séptico [OR: 2,96; IC al 95%: 1,78-4,13; p <0,001] y la existencia de neoplasia [OR: 1,73; IC al 95%: 1,27-2,20; p <0,001].

Conclusiones

. Existen varios factores disponibles tras una primera valoración en el SU, entre ellos la PCT sérica, la temperatura, la hipotensión con/sin criterios de shock séptico y la existencia de neoplasia, que predicen la existencia de bacteriemia verdadera.