Gram-positive Bacterial Infections Research Articles

The evolutionary novelty of insect defensins: from bacterial killing to toxin neutralization

Insect host defense comprises two complementary dimensions, microbial killing-mediated resistance and microbial toxin neutralization-mediated resilience, both jointly providing protection against pathogen infections. Insect defensins are a class of effectors of innate immunity primarily responsible for resistance to Gram-positive bacteria. Here, we report a newly originated gene from an ancestral defensin via genetic deletion following gene duplication in Drosophila virilis, which confers an enhanced resilience to Gram-positive bacterial infection. This gene encodes an 18-mer arginine-rich peptide (termed DvirARP) with differences from its parent gene in its pattern of expression, structure and function. DvirARP specifically expresses in D. virilis female adults with a constitutive manner. It adopts a novel fold with a 310 helix and a two CXC motif-containing loop stabilized by two disulfide bridges. DvirARP exhibits no activity on the majority of microorganisms tested and only a weak activity against two Gram-positive bacteria. DvirARP knockout flies are viable and have no obvious defect in reproductivity but they are more susceptible to the DvirARP-resistant Staphylococcus aureus infection than the wild type files, which can be attributable to its ability in neutralization of the S. aureus secreted toxins. Phylogenetic distribution analysis reveals that DvirARP is restrictedly present in the Drosophila subgenus, but independent deletion variations also occur in defensins from the Sophophora subgenus, in support of the evolvability of this class of immune effectors. Our work illustrates for the first time how a duplicate resistance-mediated gene evolves an ability to increase the resilience of a subset of Drosophila species against bacterial infection.

YajC, a predicted membrane protein, promotes Enterococcus faecium biofilm Formation in vitro and in a rat endocarditis model

Abstract Biofilm formation is a critical step in the pathogenesis of difficult-to-treat Gram-positive bacterial infections. We identified that YajC, a conserved membrane protein in bacteria, plays a role in biofilm formation of the clinically relevant Enterococcus faecium strain E1162. Deletion of yajC conferred significantly impaired biofilm formation in vitro and was attenuated in a rat endocarditis model. Mass-spectrometry analysis of supernatants of washed ΔyajC cells revealed increased amounts in cytoplasmic and cell-surface located proteins, including biofilm-associated proteins, suggesting that proteins on the surface of the yajC mutant are only loosely attached. In Streptococcus mutans YajC has been identified in complex with proteins of two cotranslational-membrane-protein-insertion pathways; the Signal-Recognition-Particle (SRP)-SecYEG-YajC-YidC1 and the SRP-YajC-YidC2 pathway, but its function is unknown. In S. mutans mutation of yidC1 and yidC2 resulted in impaired protein insertion in the cell membrane and secretion in the supernatant. The E. faecium genome contains all homologous genes encoding for the cotranslational-membrane-protein-insertion pathways. By combining the studies in S. mutans and E. faecium, we propose that YajC is involved in the stabilization of the SRP-SecYEG-YajC-YidC1 and SRP-YajC-Yid2 pathway or plays a role in retaining proteins for proper docking to the YidC insertases for translocation in and over the membrane.

Novel biaryloxazolidinone derivatives with broad-spectrum antibacterial activity, favorable drug-like profiles and in vivo efficacy against linezolid-resistant Staphylococcusaureus

The emergence of multidrug-resistant bacteria along with a declining pipeline of clinically useful antibiotics has led to the urgent need for the development of more effective antibacterial agents to treat drug-resistant bacteria. We previously discovered compound OB-158 with potent antibacterial activity but exhibited poor oral bioavailability. Herein, a systematic structural optimization of OB-158 to improve pharmacokinetic profiles yielded 26 novel biaryloxazolidinone analogues, and their activities against Gram-positive S. aureus, multidrug resistant S. aureus and Enterococcus faecalis were evaluated. Remarkably, compound 8b was identified with potent antibacterial activity against S. aureus (MIC=0.06μg/mL), MSSA (MIC=0.125μg/mL), MRSA (MIC=0.06μg/mL), LRSA (MIC=0.125μg/mL) and LREFa (MIC=0.5μg/mL). Compound 8b was demonstrated as a promising candidate through druglikeness evaluation including metabolism in microsomes and plasma, Caco-2cell permeability, plasma protein binding, cytotoxicity, and inhibition of CYP450 and human monoamine oxidase. Notably, compound 8b displayed excellent PK profile with appropriate T1/2 of 1.49h, high peak plasma concentration (Cmax=2320ng/mL), high plasma exposure (AUC0-t=8310hng/mL), and superior oral bioavailability (F=68.1%) in Sprague-Dawley rats. Ultimately, in vivo efficacy of compound 8b in a mouse model of LRSA systemic infection was also demonstrated. Taken together, compound 8b represents a promising drug candidate for the treatment of linezolid-resistant Gram-positive bacterial strains infection.

Impact Of Pharmacist Led Therapeutic Drug Monitoring of Vancomycin in Pediatric Cancer Patients

Aim This study aimed to evaluate the dosing regimen and therapeutic drug monitoring of vancomycin in this patient population. Method The study included 100 pediatric patients (3 months to 15 years) with various gram-positive bacterial infections. All patients received the initial vancomycin dose of 15 mg/kg every 6 hours. The researchers evaluated the incidence of achieving desired trough levels with this dosing regimen. Results The results revealed that patients between 1.0 and 5.9 years of age were less likely to achieve the desired trough levels with the initial vancomycin dose. Consequently, dose adjustments were made for patients with sub-therapeutic trough levels. These adjustments involved a 25% increase in the vancomycin dose. Importantly, the study found that the higher vancomycin dosing did not have any harmful effects on kidney function in pediatric patients, and no significant adverse effects were observed. Conclusion The dosing regimen of 15 mg/kg every 6 hours was unlikely to achieve the desired trough concentrations in pediatric patients with complicated infections and oncological diseases. The study recommends dose adjustments for the treatment of different infections in this population to increase the likelihood of reaching therapeutic steady-state concentrations of vancomycin.

Linezolid-Associated Thrombocytopenia: Assessment of Risk Factors in Patients without Hemato-Oncologic Diseases.

Background: Linezolid is used for Gram-positive bacterial infections. Thrombocytopenia is one of its main adverse effects resulting from myelosuppression. Several studies have assessed risk factors that may increase the risk of this adverse effect. However, most studies included patients with hemato-oncologic diseases, which may confound such assessments. This study aimed to investigate risk factors for linezolid-associated thrombocytopenia in patients without hemato-oncologic diseases. Methods: This was a multicenter retrospective case-control study of adult patients treated with linezolid twice daily for ≥3 days. Patients with hemato-oncologic diseases, active dengue fever, active COVID-19, baseline platelet count <100 × 103/mm3, concurrent therapy with trimethoprim/sulfamethoxazole or valproic acid, and a recent platelet transfusion within 7 days were excluded. Thrombocytopenia was defined as a drop in platelet count below 100 × 103/mm3. Results: Out of 158 evaluated patients, 33 developed thrombocytopenia, indicating an incidence rate of 20.9%. Of all the risk factors assessed, creatinine clearance of <60 mL/min and bacteremia/infective endocarditis were significantly associated with linezolid-associated thrombocytopenia (adjusted odds ratios, 3.25 and 5.95; 95% CI 1.12-9.45 and 1.23-28.66; p = 0.031 and 0.026, respectively). End of therapy platelet counts were significantly lower in the cases than in the controls (79 vs. 243 × 103/mm3; p < 0.001). Similarly, the percentage of platelet count change was significantly different (-55.1% vs. -10.2%; p < 0.001). Conclusions: In our study, the incidence rate of linezolid-associated thrombocytopenia was 20.9%, and we found that patients with renal impairment and bacteremia may need close monitoring of platelet counts. Prospective studies are warranted to evaluate the potential need for renal dose adjustment.

Rational design of hemocompatible hydrogel microspheres towards pathogen-associated molecular patterns removal for Gram-positive bacteria-induced sepsis

Gram-positive bacterial infection towards sepsis is often difficult to treat due to the various virulence factors such as pore-forming toxins and the corresponding complex pathogenic mechanism. While the currently reported nanoparticles for eliminating toxins are difficult to be used for hemoperfusion due to the nanoscale size, the complex preparation process and poor hemocompatibility. Herein, we design poly (sulfobetaine methacrylate-co-diallyldimethylammonium)/red blood cell membrane (PSDR) hydrogel microspheres via precipitated droplets in-situ cross-linking polymerization as hemoperfusion adsorbents to attract bacteria and adsorb the released toxins simultaneously, providing a deep treatment of sepsis caused by Gram-positive bacteria through blood purification. The PSDR microspheres show excellent and rapid adsorption of bacterial toxins in the simulated perfusion with a 75.6 % removal efficiency in 10 min. Besides, the PSDR microspheres can prevent the cells in septic blood from destroying and activating by bacterial toxins. The rational design of PSDR hydrogel microspheres is expected to provide new solutions for the deep treatment of bacteria-induced sepsis.

Optimization of fermentation conditions and medium components for chrysomycin a production by Streptomyces sp. 891-B6

BackgroundChrysomycin A (CA) is a promising antibiotic for treatment of Gram-positive bacterial infections and cancers. In order to enhance CA yield, optimization of fermentation conditions and medium components was carried out on strain Streptomyces sp. 891-B6, an UV-induced mutant with improved CA titer compared with its wide-type marine strain 891.ResultsUsing one-way experiment, the optimal fermentation conditions for CA production in 1-L shake flask were obtained as follows: 12 days of fermentation time, 5 days of seed age, 5% of inoculum volume ratio, 200 mL of loading volume and 6.5 of initial pH. By response surface methodology, the optimal medium components determined as glucose (39.283 g/L), corn starch (20.662 g/L), soybean meal (15.480 g/L) and CaCO3 (2.000 g/L).ConclusionValidation tests showed that the maximum yield of CA reached 1601.9 ± 56.7 mg/L, which was a 60% increase compared to the initial yield (952.3 ± 53.2 mg/L). These results provided an important basis for scale-up production of CA by strain 891-B6.

A decade of neonatal sepsis in Stockholm, Sweden: Gram-positive pathogens were four times as common as Gram-negatives

PurposeTo assess Gram-positive bacterial (GPB) bloodstream infection (BSI) in neonates, covering incidence, morbidity, mortality, antimicrobial resistance patterns and biomarkers in Region Stockholm, Sweden between 2006 and 2016.MethodsA population-based retrospective epidemiological study including infants with GPB-BSI, admitted to the neonatal units at Karolinska University Hospital (KUH). Data were collected from patient records, the Swedish Neonatal Quality Register, the microbiological laboratory at KUH and the Swedish Public Health Agency.ResultsWe identified 357 infants with GPB-BSI, representing an incidence of 1.47/1000 live births (LB). Group B streptococcus (GBS) was the most common pathogen causing BSI in full-term infants and early-onset sepsis (EOS) (0.20/1000 LB), while coagulase-negative staphylococci (CoNS) were predominant in infants born very preterm and in late-onset sepsis (LOS) (0.79/1000 LB). There were no fatal GBS BSI cases, but 10.2% developed meningitis. The GPB case fatality rate was 9.5% and the sepsis fatality rate 2.8%. In GPB-BSI, 1/10 did not have an elevated C-reactive protein level. Staphylococcus aureus (S. aureus) BSI increased during the study period, but no methicillin or vancomycin resistant strains were found. The antimicrobial resistance (AMR) rate was highest in CoNS isolates.ConclusionGPB-BSI was four times more common than Gram-negative BSI in neonates but resulted in lower mortality rate. GBS was the most common pathogen in full-term infants and in EOS. CoNS was the most common pathogen in LOS and infants born very preterm, and the AMR rate was high in these isolates. The increasing trend of S. aureus BSI indicates a need of further investigation.

Conventional and unconventional T-cell responses contribute to the prediction of clinical outcome and causative bacterial pathogen in sepsis patients.

Sepsis is characterized by a dysfunctional host response to infection culminating in life-threatening organ failure that requires complex patient management and rapid intervention. Timely diagnosis of the underlying cause of sepsis is crucial, and identifying those at risk of complications and death is imperative for triaging treatment and resource allocation. Here, we explored the potential of explainable machine learning models to predict mortality and causative pathogen in sepsis patients. By using a modelling pipeline employing multiple feature selection algorithms, we demonstrate the feasibility of identifying integrative patterns from clinical parameters, plasma biomarkers, and extensive phenotyping of blood immune cells. While no single variable had sufficient predictive power, models that combined five and more features showed a macro area under the curve (AUC) of 0.85 to predict 90-day mortality after sepsis diagnosis, and a macro AUC of 0.86 to discriminate between Gram-positive and Gram-negative bacterial infections. Parameters associated with the cellular immune response contributed the most to models predictive of 90-day mortality, most notably, the proportion of T cells among PBMCs, together with expression of CXCR3 by CD4+ T cells and CD25 by mucosal-associated invariant T (MAIT) cells. Frequencies of Vδ2+ γδ T cells had the most profound impact on the prediction of Gram-negative infections, alongside other T-cell-related variables and total neutrophil count. Overall, our findings highlight the added value of measuring the proportion and activation patterns of conventional and unconventional T cells in the blood of sepsis patients in combination with other immunological, biochemical, and clinical parameters.

Dalbavancina como tratamiento antibiótico de consolidación en endocarditis infecciosa, infección de dispositivos de estimulación cardiaca y bacteriemia: experiencia clínica de 7 años

IntroductionDalbavancin (DBV), a novel lipoglycopeptide with activity against Gram-positive bacterial infections, is approved for the treatment of acute bacterial skin and skin structure infections. It has linear dose-related pharmacokinetics allowing a prolonged interval between doses. It would be a good option for the treatment of patients with Gram-positive cardiovascular infections. Material and methodsRetrospective analysis of patients with cardiovascular infection (bacteremia, implantable electronic device infection and infective endocarditis [IE]) treated with DBV at Hospital Clínico San Carlos (Madrid) for 7 years (2016-2022). Patients were divided into 2 study groups: 1) IE, and 2) bacteremia. Epidemiological, clinical, microbiological and therapeutic data were analyzed. ResultsA total of 25 patients were treated with DBV for cardiovascular infection. IE was the most common indication (68%), followed by bacteremia (32%) with male predominance in both groups (64 vs. 62%) and median age of 67,7 and 57,5 years, respectively. Hundred percent of blood cultures were positive to Gram-positive microorganisms (Staphylococcus spp., Streptococcus spp. or Enterococcus spp.) in both study groups. Previously to DBV, all patients received other antibiotic therapy, both in the group of IE (median: 80 days) as in bacteremia (14,8 days). The main reason for the administration of DBV was to continue intravenous antimicrobial therapy outside the hospital in both the EI group (n=15) and the bacteremia group (n=8). DBV was used as consolidation therapy in a once- or twice-weekly regimen. Microbiological and clinical successes were reached in 84% of cases (n=21), 76,4% in IE group and 100% in bacteremia group. No patient documented adverse effects during long-term DBV treatment. ConclusionDBV is an effective and safety treatment as consolidation antibiotic therapy in IE and bacteremia produced by Gram-positive microorganisms.

The effects of drug-drug interaction on linezolid pharmacokinetics: A systematic review.

Linezolid is a commonly used antibiotic in the clinical treatment of gram-positive bacterial infections. The impacts of drug interactions on the pharmacokinetics of linezolid are often overlooked. This manuscript aims to review the medications that affect the pharmacokinetics of linezolid. In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we queried the PubMed, Embase, and Cochrane Library for publications from database establishment to November 3, 2023, using the search terms: "Linezolid" and "interaction," or "interact," or "drug-drug interaction," or "co-treatment," or "cotreatment," or "combined," or "combination." A total of 24 articles were included. Among the reported medication interactions, rifampicin, levothyroxine, venlafaxine, and phenobarbital could reduce the concentration of linezolid; clarithromycin, digoxin, cyclosporine, proton pump inhibitors, and amiodarone could increase the concentration of linezolid, while aztreonam, phenylpropanolamine, dextromethorphan, antioxidant vitamins, and magnesium-containing antacids had no significant effects on linezolid pharmacokinetics. The ratio of mean (ROM) of linezolid AUC in co-treatment with rifampicin to monotherapy was 0.67 (95%CI 0.58-0.77) and 0.63 (95%CI 0.43-0.91), respectively, in 2 studies, and co-treatment with 500mg clarithromycin to monotherapy was 1.81 (95%CI 1.49-2.13). This systematic review found that numerous drugs have an impact on the pharmacokinetics of linezolid, and the purported main mechanism may be that linezolid is the substrate of P-glycoprotein. In clinical practice, it is prudent to pay attention to the changes in linezolid pharmacokinetics caused by interactions. Conducting therapeutic drug monitoring (TDM) is beneficial to improve efficacy and reduce adverse reactions of linezolid.

Hit-to-Lead Identification and Validation of a Triaromatic Pleuromutilin Antibiotic Candidate.

Herein, we report the hit-to-lead identification of a drug-like pleuromutilin conjugate 16, based on a triaromatic hit reported in 2020. The lead arose as the clear candidate from a hit-optimization campaign in which Gram-positive antibacterial activity, solubility, and P-gp affinity were optimized. Conjugate 16 was extensively evaluated for its in vitro ADMET performance which, apart from solubility, was overall on par with lefamulin. This evaluation included Caco-2 cell permeability, plasma protein binding, hERG inhibition, cytotoxicity, metabolism in microsomes and CYP3A4, resistance induction, and time-kill kinetics. Intravenous pharmacokinetics of 16 proved satisfactory in both mice and pigs; however, oral bioavailability was limited likely due to insufficient solubility. The in vivo efficacy was evaluated in mice, systemically infected with Staphylococcus aureus, where 16 showed rapid reduction in blood bacteriaemia. Through our comprehensive studies, lead 16 has emerged as a highly promising and safe antibiotic candidate for the treatment of Gram-positive bacterial infections.

Structural-based Study to Identify the Repurposed Candidates Against Bacterial Infections.

Microbial infections are mostly caused by Gram-positive as well as Gram-negative bacteria affecting millions of people worldwide. There is an urgent need to explore existing molecules or discover new chemical entities (NCEs) against bacterial infection. The main objective of the current investigation is to explore recently US-FDA- approved drugs (2019-2023) against various targets of Gram-positive and Gram-negative bacteria using high-performance computational studies. The current study aims to find out the potential drugs of recently US-FDA-approved drugs as repurposing candidates against bacterial infections. The targets of Gram-positive and Gram-negative bacteria were identified using literature studies whereas ligands were selected from the FDA-approved drug lists of the last 5 years. Further, the drugs and targets were prepared through the LigPrep and Protein Preparation Wizard modules of Schrödinger (release 2023-1) respectively. The GlideDock and Desmond modules of Schrödinger were used for the molecular docking study and molecular dynamics simulation respectively. A total of 202 drugs were found in the FDA lists which were approved in the last five years. Out of them, 77 drugs were selected for docking study based on their properties. A total of 21 drugs have shown energetically favored binding conformation of drugs in the active site of bacterial targets. The interaction of these drugs was studied in detail using molecular dynamics (MD) simulation. The MD simulation results have shown stable dynamic conformation of triclabendazole (anti-helminthic) with topoisomerase II of gram-negative bacteria whereas solriamfetol (for obstructive sleep apnea) has shown stable dynamic conformation in the active site of restriction endonuclease of gram-positive bacteria. The identified drugs can be repurposed against Gram-positive and Gramnegative bacterial infections. However, further experimental studies are required to confirm their antibacterial potential.

Dalbavancin real-life utilization among diabetic patients suffering from infections in Italy and Spain: The DALBADIA retrospective cohort study

ObjectivesTo retrospectively describe the patterns of use of dalbavancin for treating infections in diabetic patients in Italian and Spanish standard clinical practice. MethodsDALBADIA [NCT04959799] was a multicentre, observational, retrospective cohort study, conducted in Italy and Spain. The study enrolled 97 adults with type 1 or 2 diabetes mellitus, treated with dalbavancin as per standard clinical practice for a Gram-positive bacterial infection or the Gram-positive component of a mixed infection. ResultsDalbavancin was used to treat cellulitis (18/92 patients, 19.6%), followed by prosthetic joint infection (14 patients, 15.2%), endocarditis (13 patients, 14.1%), and primary bacteraemia (10 patients, 10.9%); 78/92 (84.8%) patients had Gram-positive infections only, and 14 (15.2%) had mixed infections. The most frequently isolated microorganisms were Staphylococcus aureus in 43 (55.8% of the patients with microbial isolation), 25.6% of which methicillin-resistant; Staphylococcus epidermidis in 13 (16.9%), 53.8% of which methicillin-resistant; Enterococcus faecalis in 11 (14.3%). The main reason for the dalbavancin choice was the intent to simplify the antibiotic regimen (81.5% of cases). A multidisciplinary team participated in the treatment choice process for 53 (57.6%) patients. Dalbavancin was given as first-line antibiotic in 34 (37.0%) patients and administered as one infusion in 32 (34.8%), and as two infusions in 39 (42.4%). In total, 57/62 (91.9%) eligible patients with available assessment were judged clinically cured or improved at the end of observation. ConclusionIn clinical practice, dalbavancin was used in diabetic patients to treat ABSSSIs and other difficult-to-treat infections with a favourable safety profile and a high rate of positive clinical responses.

Procalcitonin and C-reactive protein as diagnostic biomarkers in COVID-19 and Non-COVID-19 sepsis patients: a comparative study

BackgroundThis study aimed to assess and compare procalcitonin (PCT) and C-reactive protein (CRP) levels between COVID-19 and non-COVID-19 sepsis patients. Additionally, we evaluated the diagnostic efficiency of PCT and CRP in distinguishing between Gram-positive (GP) and Gram-negative (GN) bacterial infections. Moreover, we explored the associations of PCT with specific pathogens in this context.MethodsThe study included 121 consecutive sepsis patients who underwent blood culture testing during the COVID-19 epidemic. PCT and CRP were measured, and reverse transcriptase-polymerase chain reaction (RT-PCR) was employed for the detection of COVID-19 nucleic acid. The Mann-Whitney U-test was used to compare PCT and CRP between the COVID-19 and non-COVID-19 groups. Receiver operating characteristic (ROC) curves were generated to compare PCT and CRP levels in the GN group versus the GP group for assessing the diagnostic efficiency. The kruskal-Wallis H test was applied to assess the impact of specific pathogen groups on PCT concentrations.ResultsA total of 121 sepsis patients were categorized into a COVID-19 group (n = 25) and a non-COVID-19 group (n = 96). No significant differences in age and gender were observed between the COVID-19 and non-COVID-19 groups. The comparison of biomarkers between these groups showed no statistically significant differences. The optimal cut-off values for PCT and CRP in differentiating between GP and GN infections were 1.03 ng/mL and 34.02 mg/L, respectively. The area under the ROC curve was 0.689 (95% confidence interval (CI) 0.591–0.786) for PCT and 0.611 (95% CI 0.505–0.717) for CRP. The diagnostic accuracy was 69.42% for PCT and 58.69% for CRP. The study found a significant difference in PCT levels among specific groups of pathogens (P < 0.001), with the highest levels observed in Escherichia coli infections. The frequency of Staphylococcus spp. positive results was significantly higher (36.0%) in COVID-19 compared to non-COVID-19 sepsis patients (P = 0.047).ConclusionSepsis patients with COVID-19 revealed a significantly higher culture positivity for staphylococcus spp. than the non-COVID-19 group. Both PCT and CRP showed moderate diagnostic efficiency in differentiating between GP and GN bacterial infections. PCT showed potential utility in identifying E. coli infections compared to other pathogens.

Structure-Guided Design, Synthesis, and Antivirulence Assessment of Covalent Staphylococcus aureus Sortase A Inhibitors.

Sortase A (SrtA) is a membrane-associated cysteine transpeptidase required for bacterial virulence regulation and anchors surface proteins to cell wall, thereby assisting biofilm formation. SrtA is targeted in antivirulence treatments against Gram-positive bacterial infections. However, the development of potent small-molecule SrtA inhibitors is constrained owing to the limited understanding of the mode of action of inhibitors in the SrtA binding pocket. Herein, we designed and synthesized a novel class of covalent SrtA inhibitors based on the binding mode detailed in the X-ray crystal structure of the ML346/Streptococcus pyogenes SrtA complex. ML346 analog Y40 exhibited 2-fold increased inhibitory activity on Staphylococcus aureus SrtA and showed superior inhibitory effects on biofilm formation in vitro. Y40 protected Galleria mellonella larvae fromS. aureusinfections in vivo while minimally attenuating staphylococcal growth in vitro. Our study indicates that the covalent SrtA inhibitor Y40 is an antivirulence agent that is effective againstS. aureusinfections.

P06 The effect of ciprofloxacin prophylaxis during haematopoietic cell transplantation on infection episodes, exposure to treatment antimicrobials and antimicrobial resistance: a single-centre retrospective cohort study

Abstract Background Fluroquinolone prophylaxis during haematopoietic cell transplantation (HCT) remains contentious. Objectives To determine the effectiveness of ciprofloxacin prophylaxis across different HCT indications and its association with exposure to treatment antimicrobials and antimicrobial resistance. Methods All admission episodes for HCT (N=400) in a tertiary centre between January 2020 and December 2022 were studied. Allogeneic haematopoietic cell transplantation (allo-HCT) recipients received prophylaxis with ciprofloxacin during chemotherapy-induced neutropenia, while autologous haematopoietic cell transplantation (auto-HCT) recipients did not. Results Allo-HCT was performed for 43.3% (173/400) of patients, auto-HCT for 56.7% (227/400). Allo-HCT was associated with an average of 1.01 fewer infection episodes per 100 admission days (95% CI 0.62–1.40, P&amp;lt;0.001) compared with auto-HCT. In allo-HCT, the total exposure to all antimicrobials was higher (+24.8 days of therapy [DOT]/100 admission days, P&amp;lt;0.001), as was exposure to ciprofloxacin (+40.5 DOT/100 admission days, P&amp;lt;0.001). In contrast, exposure to meropenem (−4.5 DOT/100 admission days, P=0.02), piperacillin/tazobactam (−5.2 DOT/100 admission days, P&amp;lt;0.001), aminoglycosides (−4.5 DOT/100 admission days, P&amp;lt;0.001), glycopeptides (−6.4 DOT/100 admission days, P&amp;lt;0.001), was reduced. Enterobacteriaceae isolated during allo-HCT were more resistant to ciprofloxacin (65.5%, 19/29 versus 6.1%, 2/33, P&amp;lt;0.001), ceftriaxone (65.5%, 19/29 versus 9.1%, 3/33, P&amp;lt;0.001), and other antimicrobial classes. Vancomycin-resistant enterococci were more common in allo-HCT recipients (11%, 19/173 versus 0.9%, 2/227, P&amp;lt;0.001). Inpatient mortality during allo- and auto-HCT was 9.8% (17/173) and 0.4% (1/227) respectively (P&amp;lt;0.001). An invasive bacterial infection was documented in 31.3% (125/400) of cases. Allo-HCT patients were more likely to have an invasive Gram-positive bacterial infection (23.1% versus 12.8%, P=0.01), while a difference was not observed for invasive Gram-negative bacterial infections (19.7% versus 18.5%, P=0.77). Among auto-HSCT recipients, patients with germ cell tumours had the highest probability (P for trend 0.03) of recording an invasive bacterial infection (12/23, 52.2%, 95% CI 31.3–74) compared with other indication for auto-HCT. Conclusions Ciprofloxacin prophylaxis in allo-HCT was associated with fewer infection episodes and reduced exposure to treatment antimicrobials. Mortality in auto-HCT remained low. A significant burden of antimicrobial resistance was detected in allo-HCT recipients. HCT recipients due to germ cell tumours, not receiving ciprofloxacin prophylaxis, recorded the highest incidence of invasive bacterial infections and represent a possible target group for this intervention.

Clinical application of vancomycin TDM in ventilated patients with gastrointestinal cancer: a propensity-matched analysis.

Therapeutic drug monitoring (TDM) of vancomycin is widely recommended for clinical treatment. Due to the complexity of 24-h area under the curve (AUC) guided vancomycin monitoring in clinical practice, the vancomycin trough level remains the most common and practical method. The purpose of this study was designed to investigate the differences in the safety and efficacies of vancomycin TDM based on the two different monitoring methods, and further explore the clinical application of trough-guided vancomycin monitoring in patients with gastrointestinal cancer requiring mechanical ventilation. We included a total of 78 gastrointestinal cancer patients who required mechanical ventilation due to various diseases. All patients included in this study were aged 18years or older and were treated with intravenous vancomycin therapy for more than 2days due to documented or suspected Gram-positive bacterial infections, and have at least one available vancomycin plasma concentration. First, we compared the safety and efficacies of vancomycin TDM based on different monitoring methods as trough-guided monitoring or AUC-guided monitoring. Then, based on whether the initial vancomycin concentration achieving the target trough concentration (less than 48h), patients were divided into early and delayed groups, and the clinical factors were compared between them. The primary endpoints include the incidence of new-onset acute kidney injury (AKI) or renal replacement therapy (RRT), clinical success rate and 28-day all-cause mortality. Finally, the overall relationship between trough concentration and potential covariates is screened by univariate and multivariate analysis to explore potential information covariates. The research revealed that patients with gastrointestinal cancer exhibited significantly lower initial vancomycin trough concentrations (median [interquartile range (IQR)]: 6.90[5.28-11.20] mg/L). And there were no statistically significant differences in the safety and efficacies of vancomycin TDM based on the two different monitoring methods for the primary endpoint. Moreover, base on trough-guided vancomycin monitoring, the early group demonstrated a notably shorter duration of mechanical ventilation compared with the delayed group (χ2 = 4.532; p < 0.05; Fig.2E). Propensity score weighting further confirmed that the duration of mechanical ventilation (χ2 = 6.607; p < 0.05; Fig.2F) and duration of vasoactive agent (χ2 = 6.106; p < 0.05; Fig.2D) were significantly shorter in the early group compared with delayed group. Multivariate regression analysis revealed that Cystatin C (Cys-C) was the most important variable for vancomycin target trough achievement (odds ratio, 5.274; 95% CI, 1.780 to 15.627; p = 0.003). Trough-guided vancomycin monitoring is a simple and effective marker of TDM for ventilated patients with gastrointestinal cancer. Timely achievement of target trough concentrations for vancomycin can improve partial clinical outcomes in Gram-positive bacterial infections. Cys-C level is a potentially valuable parameter for predicting the vancomycin concentration.

Experience with dalbavancin use in various gram-positive infections within Aberdeen Royal Infirmary OPAT service

PurposeDalbavancin, approved in 2014 for Gram-positive acute bacterial skin and skin structure infections (ABSSSI), has pharmacokinetics enabling treatment with one or two doses. Dalbavancin might be useful in outpatient parenteral antibiotic therapy (OPAT) of deep-seated infections, otherwise requiring inpatient admission. We documented our experience with pragmatic dalbavancin use to assess its effectiveness for varied indications, on- and off-label, as primary or sequential consolidation therapy.MethodsPatients prescribed dalbavancin between 1 December 2021 and 1 October 2022 were screened for demographics of age, sex, Charlson comorbidity index (CCI), allergies, pathogens, doses of dalbavancin, other antibiotics administered and surgery. Where available, infection markers were recorded. The primary outcome was a cure at the end of treatment. Secondary outcomes included any adverse events and for those with treatment failures, response to salvage antibiotics.ResultsSixty-seven per cent of patients were cured. Cure rates by indication were 93% for ABSSSI, 100% for bacteraemia, 90% for acute osteomyelitis, 0% for chronic osteomyelitis, 75% for native joint septic arthritis and 33% for prosthetic joint infection. Most bone and joint infections that were not cured did not have source control, and the goal of treatment was suppressive. Successful suppression rates were greater at 48% for chronic osteomyelitis and 66% for prosthetic joint infections. Adverse events occurred in 14 of 102 patients.ConclusionThis report adds to clinical experience with dalbavancin for off-label indications whilst further validating its role in ABSSSI. Dalbavancin as primary therapy in deep-seated infections merits investigation in formal clinical trials.

A Review on the Use of Third-Generation Cephalosporins on Gram-Positive and Gram-Negative Bacteria Based on its Spectrum of Activity

This review explores the clinical usage of third-generation cephalosporins, a class of broad-spectrum antibiotics that are essential for treating gram-positive and gram-negative bacterial infections in a variety of infectious conditions. These antibiotics have bactericidal action by inhibiting the synthesis of bacterial cell walls. Among the well-known members of this class are cefoperazone, cefpodoxime proxetil, ceftibuten, ceftriaxone, cefotaxime, and ceftazidime. Inhibiting transpeptidase is the mechanism of action, which, in the case of gram-negative bacteria, results in cell lysis and death. Third-generation cephalosporins are used to treat a wide range of conditions, including meningitis, genitourinary tract infections, pneumonia, infections of the skin and soft tissues, and bone and joint infections. Each cephalosporin within this generation exhibits a distinct spectrum of activity. For instance, cefpodoxime proxetil acts against Staphylococcus aureus and Klebsiella pneumoniae, whereas cefixime acts against Streptococcus pneumoniae and Escherichia coli. Neisseria gonorrhoea and Pseudomonas aeruginosa are only two examples of the many gram-positive and gram-negative bacteria that ceftriaxone is active against. This review also highlights the synergistic effects of combining third-generation cephalosporins with other antibiotics, demonstrating their versatility in managing complex infections. Despite their effectiveness, third-generation cephalosporins may not be effective against Chlamydia trachomatis. Furthermore, careful consideration of each antibiotic's spectrum guides their specific use in treating conditions such as urinary tract infections, otitis media, bronchitis, and gynecologic infections. In conclusion, the comprehensive spectrum of action of third-generation cephalosporins makes them valuable in addressing a diverse array of bacterial infections. However, their use should be judicious, considering the evolving landscape of antibiotic resistance and the specific bacterial targets for optimal therapeutic outcomes.