Empiric treatment of healthcare-associated central nervous system infections in Denmark: do we need carbapenems?

BACKGROUND

Carbapenems are widely used for empiric treatment of healthcare-associated central nervous system (CNS) infections. We investigated the feasibility of a carbapenem-sparing strategy, utilising a third-generation cephalosporin (ceftriaxone or cefotaxime) (combined with vancomycin) for the empirical treatment of healthcare-associated CNS infections in Eastern Denmark.

METHODS

The departments of neurosurgery and neuro-intensive care at Copenhagen University Hospital Rigshospitalet. First, we analysed local microbiological data (1st January 2020-31st August 2022) to identify microorganisms non-susceptible to third-generation cephalosporin. Subsequently, we assessed all carbapenem prescriptions over a three-month period for their indication and justification.

RESULTS

In total, 25,247 bacterial cultures were identified, of which 2,563 CNS-related, were included in the analysis. The positivity rate was 10.5% (n = 257/2439) for cerebrospinal-fluid samples and 75.8% (n = 95/124) for brain parenchyma. CNS samples from five individual patients revealed bacteria non-susceptible to third generation cephalosporins (Enterobacter spp. (n = 3), Pseudomonas spp. (n = 2), Klebsiella spp. (n = 2), Citrobacter freundii (n = 1)). All five patients had been hospitalised for ≥10days at the time-point of antibiotic therapy. Out of 11,626 sets of blood cultures, a total of 10 individual patients had Gram-negative blood-stream infections with resistance to ceftriaxone and piperacillin/tazobactam. 140 days-of-therapy (32%) with carbapenem in 18 patients (36%) were definitively or possibly indicated according to guidelines, none were indicated for healthcare-associated CNS-infections.

CONCLUSION

An empiric treatment strategy relying on a third-generation cephalosporin appears suitable for healthcare-associated CNS infections at our tertiary hospital, serving a population of 2.6 million. However, in patients with prolonged hospitalization (≥10 days), immunosuppression, prior broad-spectrum antibiotic use, or history of resistant Gram-negative bacteria, empirical prescription of carbapenem may be needed.

Predicting the primary infection source of Escherichia coli bacteremia using virulence-associated genes

PURPOSE

To investigate the role of E. coli virulence-associated genes (VAGs) in predicting urinary tract infection (UTI) as the source of bacteremia in two distinct hospital populations, one with a large general catchment area and one dominated by referrals.

METHODS

E. coli bacteremias identified at Department of Clinical Microbiology (DCM), Hvidovre Hospital and DCM, Rigshospitalet in the Capital Region of Denmark from October to December 2018. Using whole genome sequencing (WGS), we identified 358 VAGs from 224 E. coli bacteremia. For predictive analysis, VAGs were paired with clinical source of UTI from local bacteremia databases.

RESULTS

VAGs strongly predicting of UTI as primary infection source of bacteremia were primarily found within the pap gene family. papX (PPV 96%, sensitivity 54%) and papGII (PPV 93%, sensitivity 56%) were found highly predictive, but showed low sensitivities. The strength of VAG predictions of UTI as source varied significantly between the two hospital populations. VAGs had weaker predictions in the tertiary referral center (Rigshospitalet), a disparity likely stemming from differences in patient population and department specialization.

CONCLUSION

WGS data was used to predict the primary source of E. coli bacteremia and is an attempt on a new and different type of infection source identification. Genomic data showed potential to be utilized to predict the primary source of infection; however, discrepancy between the best performing profile of VAGs between acute care hospitals and tertiary hospitals makes it difficult to implement in clinical practice.

Questioning risk compensation: pre-exposure prophylaxis (PrEP) and sexually transmitted infections among men who have sex with men, capital region of Denmark, 2019 to 2022

BackgroundPre-exposure prophylaxis (PrEP) effectively prevents HIV, but its association with sexually transmitted infections (STIs) has raised concerns about risk compensation, potentially impacting the expansion of PrEP programmes.AimWe examined the relationship between PrEP and the incidence of chlamydia, gonorrhoea and syphilis.MethodsIn this prospective cohort study, we compared STI rates before and after PrEP initiation among users in the capital region of Denmark (2019-2022), calculating incidence rate ratios adjusted for age and testing frequency (aIRR). To pinpoint when increases began, we plotted weekly STI rates, adjusting the timeline to correspond with PrEP initiation.ResultsThe study included 1,326 PrEP users with a median age of 35 years. The STI incidence rate per 100,000 person-years rose from 35.3 before to 81.2 after PrEP start, with an aIRR of 1.35 (95% CI: 1.18-1.56). Notably, this increase preceded PrEP initiation by 10-20 weeks. Specific aIRR for chlamydia, gonorrhoea and syphilis were 1.23 (95% CI: 1.03-1.48), 1.24 (95% CI: 1.04-1.47) and 1.15 (95% CI: 0.76-1.72), respectively. In subanalyses for anatomical sites aIRR was 1.26 (95% CI: 1.01-1.56) for rectal chlamydia and 0.66 (95% CI: 0.45-0.96) for genital gonorrhoea.ConclusionWe found a 35% increase in STI incidence associated with PrEP use. It started before PrEP initiation, challenging the assumption that PrEP leads to risk compensation. Instead, the data suggest that individuals seek PrEP during periods of heightened sexual risk-taking. Consequently, PrEP programmes should include sexual health consultations, STI testing, treatment and prevention strategies to prevent HIV and improve sexual health.

Pharmacokinetics of Locally Applied Antibiotic Prophylaxis for Implant-Based Breast Reconstruction

Importance

Antibiotic irrigation of breast implants is widely used internationally, but no clinical study has investigated the pharmacokinetics of antibiotic prophylaxis in the breast implant pocket.

Objectives

To evaluate how long locally applied gentamicin, cefazolin, and vancomycin concentrations in the implant pocket remain above the minimum inhibitory concentration (MIC) for the most common bacterial infections and to measure systemic uptake.

Design, Setting, and Participants

This prospective cohort study was performed at the Department of Plastic Surgery and Burns Treatment, Rigshospitalet, Copenhagen, Denmark, between October 25, 2021, and September 22, 2022, among 40 patients undergoing implant-based breast reconstruction who were part of the ongoing BREAST-AB trial (Prophylactic Treatment of Breast Implants With a Solution of Gentamicin, Vancomycin and Cefazolin Antibiotics for Women Undergoing Breast Reconstructive Surgery: a Randomized Controlled Trial). Patients were randomized to receive locally applied gentamicin, cefazolin, and vancomycin or placebo. Samples were obtained from the surgical breast drain and blood up to 10 days postoperatively.

Exposures

The breast implant and the implant pocket were irrigated with 160 μg/mL of gentamicin, 2000 μg/mL of cefazolin, and 2000 μg/mL of vancomycin in a 200-mL saline solution.

Main Outcomes and Measures

The primary outcome was the duration of antibiotic concentrations above the MIC breakpoint for Staphylococcus aureus according to the Clinical and Laboratory Standards Institute: gentamicin, 4 μg/mL; cefazolin, 2 μg/mL; and vancomycin, 2 μg/mL. Secondary outcomes included the time above the MIC for Pseudomonas aeruginosa and other relevant bacteria, as well as systemic uptake.

Results

The study included 40 patients (median age, 44.6 years [IQR, 38.3-51.4 years]; median body mass index, 23.9 [IQR, 21.7-25.9]) with a median number of 3 drain samples (range, 1-10 drain samples) and 2 blood samples (range, 0-6 blood samples). Vancomycin and cefazolin remained above the MIC for S aureus significantly longer than gentamicin (gentamicin, 0.9 days [95% CI, 0.5-1.2 days] for blood samples vs 6.9 days [95% CI, 2.9 to 10.9 days] for vancomycin [P = .02] vs 3.7 days [95% CI, 2.2-5.2 days] for cefazolin [P = .002]). The gentamicin level remained above the MIC for P aeruginosa for 1.3 days (95% CI, 1.0-1.5 days). Only cefazolin was detectable in blood samples, albeit in very low concentrations (median concentration, 0.04 μg/mL [range, 0.007-0.1 μg/mL]).

Conclusions and Relevance

This study suggests that patients treated with triple-antibiotic implant irrigation during breast reconstruction receive adequate prophylaxis for S aureus and other common implant-associated, gram-positive bacteria. However, the protection against P aeruginosa may be inadequate.

Emergence of linezolid-resistant Enterococcus faecium in a tertiary hospital in Copenhagen

Linezolid is used as first-line treatment of infections caused by vancomycin-resistant Enterococcus faecium. However, resistance to linezolid is increasingly detected. The aim of the present study was to elucidate the causes and mechanisms for the increase in linezolid-resistant E. faecium at Copenhagen University Hospital - Rigshospitalet. We therefore combined patient information on linezolid treatment with whole-genome sequencing data for vancomycin- or linezolid-resistant E. faecium isolates that had been systematically collected since 2014 (n=458). Whole-genome sequencing was performed for multilocus sequence typing (MLST), identification of linezolid resistance-conferring genes/mutations and determination of phylogenetically closely related strains. The collection of E. faecium isolates belonged to prevalent vancomycin-resistant MLST types. Among these, we identified clusters of closely related linezolid-resistant strains compatible with nosocomial transmission. We also identified linezolid-resistant enterococcus isolates not genetically closely related to other isolates compatible with de novo generation of linezolid resistance. Patients with the latter isolates were significantly more frequently exposed to linezolid treatment than patients with related linezolid-resistant enterococcus isolates. We also identified six patients who initially carried a vancomycin-resistant, linezolid-sensitive enterococcus, but from whom vancomycin-resistant, linezolid-resistant enterococci (LVRE) closely related to their initial isolate were recovered after linezolid treatment. Our data illustrate that linezolid resistance may develop in the individual patient subsequent to linezolid exposure and can be transmitted between patients in a hospital setting.

Vancomycin-resistant Enterococcus faecium: should we screen on admission?

Denmark has experienced an increase in the proportion of invasive vancomycin-resistant Enterococcus faecium (VRE) since 2002 (e.g. <4% in 2015, 7.1% in 2017 and 12% in 2018). At Rigshospitalet, we employ active screening at departments with high prevalence or in case of outbreaks. This includes the collection of rectal swabs specifically for VRE screening. Our purpose was to describe the carrier prevalence of vancomycin-resistant enterococci among acute patients admitted to the Neurointensive Care Unit, Department of Neuroanaesthesiology, Rigshospitalet, Copenhagen, Denmark (NICU). Between April 2018 and January 2019, we investigated 99 consecutive rectal swabs from patients admitted to NICU. The primary outcome was prevalence of VRE carriage. The median age was 64 years (range 23-87) and gender was equally distributed (Female = 47, Male = 46). 26 (28%) had previously been admitted within 179 days and 67 patients (72%) had no hospital admissions within 180 days prior to the admission to NICU. Of the 93 rectal swabs, 2 (2%, 95% CI 0.26-7.55%) were positive for vanA and none were positive for vanB. Routine screening of all patients at admission may be effective in hospital settings with high VRE prevalence, whereas the benefit of screening for VRE in hospitals with a low prevalence may be restricted to specific patient populations.

Synergy between Mecillinam and Ceftazidime/Avibactam or Avibactam against Multi-Drug-Resistant Carbapenemase-Producing Escherichia coli and Klebsiella pneumoniae

Background: Carbapenemase-producing Klebsiella pneumoniae and Escherichia coli have become a significant global health challenge. This has created an urgent need for new treatment modalities. We evaluated the efficacy of mecillinam in combination with either avibactam or ceftazidime/avibactam against carbapenemase-producing clinical isolates. Materials and methods: Nineteen MDR clinical isolates of K. pneumoniae and E. coli were selected for the presence of blaKPC, blaNDM, blaOXA or blaIMP based on whole-genome sequencing and phenotypic susceptibility testing. We tested the synergy between mecillinam and avibactam or ceftazidime/avibactam. We used time−kill studies in vitro and a mouse peritonitis/sepsis model to confirm the synergistic effect. We investigated avibactam’s impact on mecillinam´s affinity for penicillin-binding proteins with a Bocillin assay, and cell changes with phase-contrast and confocal laser scanning microscopy. Results: Mecillinam combined with ceftazidime/avibactam or avibactam substantially reduced MICs (from up to >256 µg/mL to <0.0016 µg/mL) for 17/18 strains. Significant log-CFU reductions were confirmed in time−kill and in vivo experiments. The Bocillin assay did not reveal changes. Conclusion: Mecillinam in combination with avibactam or ceftazidime/avibactam has a notable effect on most types of CPEs, both in vitro and in vivo. The mecillinam/avibactam combination treatment could be a new efficient antibiotic treatment against multi-drug-resistant carbapenemase-producing Gram-negative pathogens.

Early biomarker-guided prediction of bloodstream infection in critically ill patients: C-reactive protein, procalcitonin and leukocytes

Background

Bloodstream infections (BSIs) often lead to critical illness and death. The primary aim of this study was to determine the diagnostic accuracy of the biomarkers C-reactive protein (CRP), procalcitonin (PCT), and leukocyte count for the diagnosis of BSI in critically ill patients.

Methods

This was a nested case–control study based on the Procalcitonin And Survival Study (PASS) trial (n = 1200). Patients who were admitted to the intensive care unit (ICU) <24 hours, and not expected to die within <24 hours, were recruited. For the current study, we included patients with a BSI within ±3 days of ICU admission and matched controls without a BSI in a 1:2 ratio. Diagnostic accuracy for BSI for the biomarkers on days 1, 2, and 3 of ICU admission was assessed. Sensitivity, specificity, and negative and positive predictive values were calculated for prespecified thresholds and for a data-driven cutoff.

Results

In total, there were 525 patients (n = 175 cases, 350 controls). The fixed low threshold for all 3 biomarkers (CRP = 20 mg/L; leucocytes = 10 × 10⁹/L; PCT = 0.4 ng/mL) resulted in negative predictive values on day 1: CRP = 0.91; 95% CI, 0.75–1.00; leukocyte = 0.75; 95% CI, 0.68–0.81; PCT = 0.91; 95% CI, 0.84–0.96). Combining the 3 biomarkers yielded similar results as PCT alone (P = .5).

Conclusions

CRP and PCT could in most cases rule out BSI in critically ill patients. As almost no patients had low CRP and ∼20% had low PCT, a low PCT could be used, along with other information, to guide clinical decisions.

The vaginal microbiome following orally administered probiotic

INTRODUCTION

Here we present a longitudinal shotgun sequencing metagenomics study of 16 healthy, Danish women in the reproductive age. The aim of the study was to investigate whether lactobacilli, orally consumed, had any impact on the vaginal microbiome and its functional potential.

MATERIALS AND METHODS

The 16 women aged 19-45 years were recruited from Copenhagen, Denmark. One baseline vaginal sample (day 0) and two study samples (day 25-30 and day 55-60, respectively) were sampled. The vaginal samples were analyzed by shotgun metagenomics.

RESULTS

We detected 26 species in the vaginal microbiota of the 16 women, of which six belonged to the Lactobacillus genus. We observed three vaginal microbiome clusters mainly dominated by Gardnerella vaginalis, Lactobacillus iners or Lactobacillus crispatus. The oral probiotic had no detectable effect on either the composition or the functional potential of the vaginal microbiota.

DISCUSSION

Most of the study subjects (11 out of 16 women) exhibited only minor changes in the vaginal microbiome during the treatment with probiotics. Any compositional changes could not be associated to the probiotic treatment. Future studies may benefit from an increased number of participants, and administration of the probiotics during conditions with bacterial imbalance (e.g. during/after antibiotic treatment) or the use of different Lactobacillus spp. known to colonize the vagina.

The inflamed sputum in lower respiratory tract infection: l-lactate levels are correlated to neutrophil accumulation

Lower respiratory tract infections (LRTI) are common, but little is known about the response of biomarkers of inflammation in the lungs. Therefore, our primary aim was to compare the concentration of l-lactate to the concentration of neutrophils in sputum and systemic markers of infection. Because it is difficult to differentiate viral and bacterial infection on the basis of clinical presentation in LRTI, our secondary aim was to evaluate if l- and d-lactate may serve as markers of local inflammation as representatives of neutrophils and bacteria, respectively.

METHODS

Patients with acute LRTI were prospectively recruited. Sputum samples were collected and analysed for neutrophil count, l-lactate and d-lactate. We had data on pathogens from sputum cultures and polymerase chain reaction (PCR) (atypical bacteria, virus) and C-reactive protein (CRP) from blood.

RESULTS

In 44 sputum samples from 32 patients, the median (interquartile range (IQR)) sputum neutrophil granulocyte count was 0.615 × 10⁷  cells/mL (0.236-1.575). The sputum neutrophil granulocyte count was associated with sputum l-lactate (p = 0.011) and CRP (p = 0.018), but not with d-lactate (p = 0.177). There was a strong association between sputum d-lactate and l-lactate (p < 0.0001).

CONCLUSION

As l-lactate in sputum is closely correlated to sequestration of neutrophils in the lungs, l-lactate is a marker for local inflammation in LRTI and a potential biomarker in clinical management of LRTI. On expectorated sputum, d-lactate had no clinical relevance.

Does macrolide use confer risk of out-of-hospital cardiac arrest compared with penicillin V? A Danish national case-crossover and case-time-control study

INTRODUCTION AND OBJECTIVES

Macrolides have been associated with proarrhythmic properties, but the evidence is conflicting. We evaluated the risk of out-of-hospital cardiac arrest (OHCA) associated with specific macrolides in a retrospective study. Associations between specific macrolides and OHCA were examined by conditional logistic regression analyses in case-crossover and case-time-control models, using penicillin-V treatment as the comparative reference. From nationwide registries, we identified all OHCAs in Denmark from 2001 to 2010 and use of antibiotics.

ETHICS

The present study was approved by the Danish Data Protection Agency (Danish Data Protection Agency (ref.no. 2007-58-0015, local ref.no. GEH-2014-017, (I-Suite.nr. 02 735)).

PARTICIPANTS

We identified 29 111 patients with an OHCA. Of these, 514 were in macrolide treatment ≤7 days before OHCA and 1237 in penicillin-V treatment.

RESULTS

In the case-crossover analyses, overall macrolide use was not associated with OHCA with penicillin V as negative comparative reference (OR=0.90; 95% CI 0.73 to 1.10). Compared with penicillin-V treatment, specific macrolides were not associated with increased risk of OHCA: roxithromycin (OR=0.97; 95% CI 0.74 to 1.26), erythromycin (OR=0.68; 95% CI 0.44 to 1.06), clarithromycin (OR=0.95; 95% CI 0.61 to 1.48) and azithromycin (OR=0.85; 95% CI 0.57 to 1.27).Similar results were obtained using case-time-control models: overall macrolide use (OR=0.81; 95% CI 0.62 to 1.06) and specific macrolides (roxithromycin (OR=0.70; 95% CI 0.49 to 1.00), erythromycin (OR=0.67; 95% CI 0.38 to 1.18), clarithromycin (OR=0.75; 95% CI 0.41 to 1.39) or azithromycin (OR=1.17; 95% CI 0.70 to 1.95)).

CONCLUSION

The risk of OHCA during treatment with macrolides was similar to that of penicillin V, suggesting no additional risk of OHCA associated with macrolides.