Time to blood culture positivity- an independent predictor of mortality in Streptococcus pyogenes bacteraemia

Efficacy of Ceftazidime-avibactam in treating Gram-negative infections: a systematic review and meta-analysis

INTRODUCTION

Ceftazidime-avibactam (CAZ-AVI) has emerged as a promising treatment option for Gram-negative infections, particularly those caused by CAZ-Non-Susceptible (NS) pathogens. This systematic review and meta-analysis aim to assess the efficacy and safety of CAZ-AVI in these challenging infections.

METHODS

We systematically queried EMBASE, Cochrane CENTRAL, and PubMed/Medline for studies published until September 15, 2024. Randomized Controlled Trials (RCTs) evaluating CAZ-AVI against Gram-negative infections were included. A meta-analysis was performed to calculate pooled odds ratios (OR) for both clinical and microbiological success.

RESULTS

A total of 146 studies were identified through database searches, leading to the inclusion of 17 studies. Among the efficacy studies for Gram-negative pathogens, there was no significant difference in clinical success rates for CAZ-AVI compared to comparators (pooled OR: 0.90, p = 0.22), and a non-significant increase in microbiological success was observed (pooled OR: 1.20, p = 0.41). In contrast, for CAZ-NS pathogens, six studies reported no significant difference in clinical cure rates (pooled OR: 0.77, p = 0.24), while four studies indicated a non-significant increase in microbiological cure rates (pooled OR: 1.83, p < 0.02).

CONCLUSIONS

This study suggests that CAZ-AVI is a viable option for treating Gram-negative infections, including CAZ-NS pathogens. While it has shown promising activity against these resistant pathogens, its clinical and microbiological success rates are comparable to other antibiotics in the overall analysis. However, CAZ-AVI may offer an advantage in managing resistant infections. These findings underscore the need to consider CAZ-AVI in treatment guidelines and emphasize the importance of antibiotic stewardship programs to optimize its use and prevent resistance. Ongoing monitoring of resistance patterns and patient outcomes is essential to ensure its long-term efficacy.

A mathematical model to estimate the probability of blood cultures positive for pyogenic streptococci

Aims

The aim of this study was to assess the possible use of time to positivity (TTP) of blood cultures (BCs) collected at the Emergency Department (ED) to estimate the probability of pyogenic streptococci versus other Gram positive cocci in pairs and chains, such as Streptococcus pneumoniae, other viridans group streptococci or enterococci.

Methods

All patients 18 years of age or older evaluated at the ED from whom BCs were collected and were positive for Gram positive cocci in pairs and chains at the microscopic examination, were included in the study. The BCs included were collected by venipuncture, were mono-microbial and were the first bottles that flagged positive in each set. Complete blood count requested simultaneously with BCs along with medical history taken by the ED physician were also evaluated.

Results

In our case series, all BCs positive for Gram positive cocci in pairs or chains at microscopic examination with a TTP ≤6.3 hours were consistent with a pyogenic streptococcus (100% specificity; 95% CI: 92.7-100). Consequently, a TTP ≤6.3 hours has a 100% positive predictive value (95% CI: 30.9-100). Conversely, no pyogenic streptococci were recovered from positive BCs with a TTP >12.6 hours. Therefore, as screening test, it has 100% sensitivity (95% CI: 77-100) and 100% negative predictive value (95% CI: 83.4-100). The binomial logistic regression model showed how as TTP increases, in BCs positive for Gram positive cocci in pairs and chains at the microscopic examination, the probability of a positive result for pyogenic streptococci decreases (odds ratio: 0.548; 95% confidence interval: 0.387-0.775; P=0.001).

Conclusions

The results of this study are an adjunctive tool to clinical aspects and fast microbiology laboratory tests to help assessing the likelihood of a positive blood culture for pyogenic streptococci.

Diagnostic and prognostic value of time to positivity in blood cultures. An opinion paper

Time to positivity (TTP) refers to the duration required for a microbiological culture test to indicate a positive result, marking the onset of detectable bacterial or fungal growth in the sample. Numerous variables, including patient characteristics, infection source, former antimicrobial therapy, blood sample volume, and sample transportation time can influence the value of TTP. Several studies have been conducted on bloodstream infections, whereas studies on the clinical significance of yeast TTP are quite limited in the literature. Furthermore, many studies are retrospective and have a small sample size. In this opinion paper, we have formulated some questions and attempted to provide answers based on the available literature and our perspective. The objective of this opinion paper is to summarise current knowledge based on the literature, aiming to offer a critical perspective, particularly on aspects with weaker evidence, which could guide future studies in this area. We believe that TTP of blood cultures appears to exhibit considerable potential and may prove to be a valuable tool in clinical practice for estimating patient mortality risk and guiding antimicrobial therapy choices. Topics discussed include the diagnostic and prognostic role of TTP in Gram-positive and Gram-negative bacteremias and in candidemias, and the significance of differential time to positivity (DTTP). In summary, our opinion is that, based on the available literature, it is not possible to determine whether TTP provides prognostic information, particularly concerning candidemia. Therefore, clinical decisions cannot be systematically based on this parameter.

Time-to-Positivity for Candida in Bloodstream Infections: Prognostic Implications for Mortality

Background Candida-associated catheter-related bloodstream infections (CRBSIs) present a significant challenge in clinical settings, particularly among patients with central venous catheters (CVCs). Time-to-positivity (TTP) of blood cultures, an indicator of fungal load, may provide insights into infection prognosis and severity. This study evaluates the role of TTP in Candida-associated bloodstream infections and its impact on patient outcomes. Materials and methods This cross-sectional observational study, conducted from July 2023 to June 2024 at Saveetha Medical College, involved collecting blood cultures from intensive care unit (ICU) patients with suspected candidemia. Blood cultures were processed using the BacT/ALERT 3D system (bioMérieux, Marcy l'Étoile, France), with TTP recorded for each Candida-positive culture. Species identification was performed using MALDI-TOF MS (Bruker Daltonics, Germany). Species-specific 30-day mortality was analyzed to assess the impact of TTP on survival. Results Of 7447 blood cultures from ICU patients, 2349 were positive, with a 2.42% prevalence of Candida sp. Among 57 candidemia patients, the median TTP for deceased patients was 24 hours, compared to 25 hours for survivors (p=0.001). C. auris exhibited the highest mortality rate (56.25%) with a median TTP of 16.5 hours, whereas C. albicans had no associated mortality and a median TTP of 28.5 hours. Shorter TTP was consistently associated with higher mortality across Candida species. Conclusion This study highlights the prognostic value of TTP in Candida-associated bloodstream infections, with shorter TTP correlating with higher mortality. The findings underscore the need for rapid diagnosis and aggressive treatment, particularly for high-risk species like C. auris and C. glabrata. Further research is needed to refine the clinical application of TTP and develop targeted treatment strategies.

Time to positivity is a risk factor for death among patients with bloodstream infections: a population-based cohort

OBJECTIVES

Studies examining time to positivity (TTP) of blood cultures as a risk factor for death have shown conflicting results. The study objective was to examine the effect of TTP on all-cause-30-day case-fatality among a population-based cohort of patients with bloodstream infections (BSI).

METHODS

A retrospective cohort study including all residents of Queensland, Australia with incident monomicrobial BSI managed in the publicly funded healthcare system from 2000 to 2019 was performed. Clinical, TTP and all-cause 30-day case-fatality information was obtained from state-wide sources.

RESULTS

A cohort of 88 314 patients was assembled. The median TTP was 14 hours, with 5th, 25th, 75th, and 95th percentiles of 4, 10, 20, and 53 hours, respectively. The TTP varied significantly by BSI aetiology. The 30-day all-cause case-fatality rate was 2606/17 879 (14.6%), 2834/24 272 (11.7%), 2378/20 359 (11.7%), and 2752/22 431 (12.3%) within the first, second, third, and fourth TTP quartiles, respectively (p < 0.0001). After adjustment for age, sex, onset, comorbidity, and focus of infection, TTP within 10 hours (first quartile) was associated with a significantly increased risk for death (odds ratio 1.43; 95% CI, 1.35-1.50; p < 0.001). After adjustment for confounding variables (odds ratio; 95% CI), TTP within the first quartile for Staphylococcus aureus (1.56; 1.41-1.73), Streptococcus pneumoniae (1.91; 1.49-2.46), β-hemolytic streptococci (1.23; 1.00-1.50), Pseudomonas species (2.23; 1.85-2.69), Escherichia coli (1.37; 1.23-1.53), Enterobacterales (1.38; 1.16-1.63), other Gram-negatives (1.68; 1.36-2.06), and anaerobes (1.58; 1.28-1.94) increased the risk for case-fatality.

DISCUSSION

This population-based analysis provides evidence that TTP is an important determinant of mortality among patients with BSI.

Predictors of Mortality of Streptococcal Bacteremia and the Role of Infectious Diseases Consultation: A Retrospective Cohort Study

BACKGROUND

Streptococcal bacteremia is associated with high mortality. Thia study aims to identify predictors of mortality among patients with streptococcal bacteremia.

METHODS

This retrospective study was conducted at the Lausanne University Hospital, Switzerland, and included episodes of streptococcal bacteremia among adult patients from 2015 to 2023.

RESULTS

During the study period, 861 episodes of streptococcal bacteremia were included. The majority of episodes were categorized in the Mitis group (348 episodes; 40%), followed by the Pyogenic group (215; 25%). Endocarditis was the most common source of bacteremia (164; 19%). The overall 14-day mortality rate was 8% (65 episodes). The results from the Cox multivariable regression model showed that a Charlson comorbidity index >4 (P .001; hazard ratio [HR], 2.87; confidence interval [CI]: 1.58-5.22), Streptococcus pyogenes (P = .011; HR, 2.54;CI: 1.24-5.21), sepsis (P < .001; HR, 7.48; CI: 3.86-14.47), lower respiratory tract infection (P = .002; HR, 2.62; CI: 1.42-4.81), and absence of source control interventions within 48 hours despite being warranted (P = .002; HR, 2.62; CI: 1.43-4.80) were associated with 14-day mortality. Conversely, interventions performed within 48 hours of bacteremia onset, such as infectious diseases consultation (P < .001; HR, 0.29; CI: .17-.48) and appropriate antimicrobial treatment (P < .001; HR, .28; CI: .14-.57), were associated with improved outcome.

CONCLUSIONS

Our findings underscore the pivotal role of infectious diseases consultation in guiding antimicrobial treatment and recommending source control interventions for patients with streptococcal bacteremia.

Increasing Rate of Fatal Streptococcus pyogenes Bacteriemia-A Challenge for Prompt Diagnosis and Appropriate Therapy in Real Praxis

Streptococcus pyogenes, group A streptococci (GAS) bacteriaemia, is a life-threatening infection with high mortality, requiring fast diagnosis together with the use of appropriate antibiotic therapy as soon as possible. Our study analysed data from 93 patients with GAS bacteraemia at the General University Hospital in Prague between January 2006 and March 2024. In the years 2016-2019 there was an increase in GAS bacteraemia. Mortality in the period 2006-2019 was 21.9%; in the period 2020-2024, the mortality increased to 41.4%, p = 0.08. At the same time, in the post-2020 period, the time from hospital admission to death was reduced from 9.5 days to 3 days. A significant predictor of worse outcome in this period was high levels of procalcitonin, >35.1 µg/L (100% sensitivity and 82.35% specificity), and lactate, >5 mmol/L (90.91% sensitivity and 91.67% specificity). Myoglobin was a significant predictor in both compared periods, the AUC was 0.771, p = 0.044, and the AUC was an even 0.889, p ≤ 0.001, respectively. All isolates of S. pyogenes were susceptible to penicillin, and resistance to clindamycin was 20.3% from 2006-2019 and 10.3% in 2020-2024. Appropriate therapy was initiated in 89.1%. and 96.6%, respectively. We hypothesise that the increase in mortality after 2020 might be due to a decrease in the immune status of the population.

The Epidemiological, Clinical, and Microbiological Features of Patients with Burkholderia pseudomallei Bacteraemia-Implications for Clinical Management

Patients with melioidosis are commonly bacteraemic. However, the epidemiological characteristics, the microbiological findings, and the clinical associations of Burkholderia pseudomallei bacteraemia are incompletely defined. All cases of culture-confirmed melioidosis at Cairns Hospital in tropical Australia between January 1998 and June 2023 were reviewed. The presence of bacteraemia was determined and correlated with patient characteristics and outcomes; 332/477 (70%) individuals in the cohort were bacteraemic. In multivariable analysis, immunosuppression (odds ratio (OR) (95% confidence interval (CI)): (2.76 (1.21-6.27), p = 0.02), a wet season presentation (2.27 (1.44-3.59), p < 0.0001) and male sex (1.69 (1.08-2.63), p = 0.02), increased the likelihood of bacteraemia. Patients with a skin or soft tissue infection (0.32 (0.19-0.57), p < 0.0001) or without predisposing factors for melioidosis (0.53 (0.30-0.93), p = 0.03) were less likely to be bacteraemic. Bacteraemia was associated with intensive care unit admission (OR (95%CI): 4.27 (2.35-7.76), p < 0.0001), and death (2.12 (1.04-4.33), p = 0.04). The median (interquartile range) time to blood culture positivity was 31 (26-39) hours. Patients with positive blood cultures within 24 h were more likely to die than patients whose blood culture flagged positive after this time (OR (95%CI): 11.05 (3.96-30.83), p < 0.0001). Bacteraemia portends a worse outcome in patients with melioidosis. Its presence or absence might be used to help predict outcomes in cases of melioidosis and to inform optimal clinical management.

Diagnosis behind the mask: A rare case of infected Charcot's spine

Charcot's spine is a very uncommon long-term complication of spinal cord injury. Infection of the spine is a common pathology, but infection of a Charcot's spine is rare and is challenging to diagnose, especially in differentiating between the Charcot defect and the osteomyelitis defect. Surgical reconstruction has to be extremely individualized. A 65-year-old man with a history of thoracic spinal cord injury with paraplegia 49 years ago was admitted to our hospital with high fever and aphasia. After a thorough diagnostic process, destructive Charcot's spine and secondary infection were diagnosed. This report additionally reviews the surgical management of secondary infected destructive lumbar Charcot's spine and follows the patient's recovery and postoperative quality of life.

Novel evidence on sepsis-inducing pathogens: from laboratory to bedside

Sepsis is a life-threatening condition and a significant cause of preventable morbidity and mortality globally. Among the leading causative agents of sepsis are bacterial pathogens Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes, along with fungal pathogens of the Candida species. Here, we focus on evidence from human studies but also include in vitro and in vivo cellular and molecular evidence, exploring how bacterial and fungal pathogens are associated with bloodstream infection and sepsis. This review presents a narrative update on pathogen epidemiology, virulence factors, host factors of susceptibility, mechanisms of immunomodulation, current therapies, antibiotic resistance, and opportunities for diagnosis, prognosis, and therapeutics, through the perspective of bloodstream infection and sepsis. A list of curated novel host and pathogen factors, diagnostic and prognostic markers, and potential therapeutical targets to tackle sepsis from the research laboratory is presented. Further, we discuss the complex nature of sepsis depending on the sepsis-inducing pathogen and host susceptibility, the more common strains associated with severe pathology and how these aspects may impact in the management of the clinical presentation of sepsis.

Infection or Contamination with Rothia, Kocuria, Arthrobacter and Pseudoglutamicibacter-a Retrospective Observational Study of Non-Micrococcus Micrococcaceae in the Clinic

Rothia, Kocuria, Arthrobacter, and Pseudoglutamicibacter are bacterial species within the family Micrococcaeae. Knowledge of human infections due to these bacteria is limited. This study aimed to examine features of infections caused by non-Micrococcus Micrococcaeae (NMM). Findings of NMM from blood cultures and other sterile cultures from 2012 to 2021 were identified from the records of the Department of Clinical Microbiology in Region Skåne, Lund, Sweden. Medical records were retrospectively reviewed. True infection was defined as having signs of infection, no other more likely pathogen, and no other focal infection, together with two positive blood cultures or one positive blood culture and an intravascular device. A total of 197 patients with findings of NMM in blood cultures were included. Among adult patients with bacteremia, 29 patients (22%) were considered to have a true infection. Adults with true infection were significantly more likely to have malignancy (69%), leukopenia (62%), and treatment with chemotherapeutics (66%) compared to patients with contaminated samples (24%, 3%, and 8%, respectively) (P < 0.001). A total of 31 patients had findings of NMM in other sterile cultures, and infections were considered true in joints (n = 4), a pacemaker (n = 1), and peritoneal dialysis fluid (n = 1). Infections due to NMM occur but are rare. Growth of NMM in blood cultures should be suspected to be a true infection mainly in immunocompromised patients.

Time to positivity of blood cultures in bloodstream infections with Streptococcus dysgalactiae and association with outcome

PURPOSE

Invasive infections with Streptococcus dysgalactiae predominantly occur in persons of older age with substantial morbidity and mortality. Time to positivity from blood cultures (TTP) has been shown to be a prognostic indicator in bloodstream infections caused by other beta-haemolytic streptococci. This study aimed to determine any possible association between TTP and outcome in invasive infections due to S. dysgalactiae.

MATERIALS AND METHODS

Episodes of S. dysgalactiae bacteraemia, that occurred during 2015-2018 in the Region of Skåne, Sweden, were identified through the laboratory database and retrospectively studied. Any association with TTP and the primary outcome, death within 30 days and the development of sepsis or disease deterioration within 48 hours from blood culturing as secondary outcomes were investigated.

RESULTS

Among the 287 episodes of S. dysgalactiae bacteraemia, 30-day mortality rate was 10% (n = 30). Median TTP was 9.3 h (interquartile range 8.0-10.3 h). Median TTP was statistically significantly shorter in patients who died within 30 days compared to surviving patients (7.7 vs 9.3 h, p = .001, Mann-Whitney U test). Short TTP(≤ 7.9 h) was still associated with 30-day mortality when adjusting for age, (OR 4.4, 95% CI 1.6-12.2, p = .004). Associations between secondary outcomes and levels of TTP were not observed.

CONCLUSION

TTP may be an important prognostic indicator for 30-day mortality in patients with bloodstream infections due to S. dysgalactiae.