Journal of Microbiology Immunology and Infection最新文献

Objectives: To explore factors significantly associated with plasma procalcitonin (PCT) concentration elevation among patients with monomicrobial Gram-negative bacteremia.

Methods: Sepsis patients hospitalized in intensive care units between 2020 and 2024 were eligible for this study. Their demographic characteristics, comorbidities, development of shock and disseminated intravascular coagulation, key laboratory data-including plasma C-reactive protein (CRP) and PCT concentrations-sonographic and radiographic findings, and septic workup results were collected. To determine the median PCT level, patients with monomicrobial Gram-negative bacteremia were stratified into two equal groups.

Results: Patients with bacteremia secondary to biliary tract infection (n = 24), urinary tract infection (UTI; n = 118), and primary source (n = 71), showed high proportions of Enterobacterales species as causative etiologies. A total of 358 patients with monomicrobial Gram-negative bacteremia were included in the final analysis. Patients with plasma PCT concentrations above the median value (20.2 ng/mL) did not exhibit higher mortality rates compared to those with concentrations below the median. Additionally, diabetes mellitus, UTI associated with hydronephrosis, and shock development were identified as independent predictors for markedly elevated plasma PCT concentrations among patients with monomicrobial Gram-negative bacteremia (odds ratio [OR], 1.66, 3.83, and 2.09; 95 % confidence interval [CI], 1.02-2.70, 1.64-8.93, and 1.25-3.50; P values, 0.043, 0.002, and 0.005, respectively). In contrast, the presence of Child-Pugh class C liver cirrhosis was a negative predictor of high plasma PCT concentrations (OR 0.35, 95 % CI 0.11-0.97, and P = 0.049).

Conclusions: This study recognized factors with significant impact on plasma PCT concentrations among patients with monomicrobial Gram-negative bacteremia.

Background: Hemodialysis (HD) patients with nasal Staphylococcus aureus carriage are at an increased risk of S. aureus infection.

Purpose: This study investigated the incidence of S. aureus bacteremia and associated mortality in HD patients receiving active screening and decolonization (ASD) program for nasal S. aureus carrier in a teaching hospital HD unit.

Methods: The ASD program was divided into five stages: 1: preintervention, 2: preparation, 3: intervention, 4: interruption, and 5: reintervention. Nasal screening was conducted every 3 months in stages 3 and 5. Patients colonized with S. aureus received decolonization with mupirocin to the nares and 4 % chlorhexidine gluconate body wash. S. aureus bacteremia and mortality were assessed. Whole-genome sequencing was conducted on S. aureus isolate in stage 3.

Results: In preintervention stage, the bacteremia incidence and mortality rate were 7.8 and 3.1 cases per 100 patient-years(PY). In the intervention stage, the incidence rate decreased to 1 case per 100 PY without mortality. In the reintervention stage, the incidence and mortality rates were 2.1 and 0.6 cases per 100 PY. The rates in stages 3, 4, and 5 were significantly lower than those in preintervention stage (p < 0.05). Genomic analysis of S. aureus isolates from stage 3 revealed genetically diversity. High-level mupirocin-resistant S. aureus isolates carrying mupA-bearing plasmids were identified.

Conclusions: ASD programs for S. aureus carrier may improve clinical outcomes in HD units. However, mupirocin resistance may emerge after decolonization, indicating a need for ongoing monitoring and alternative decolonization strategies.

Background: Microbes and their metabolites are implicated in respiratory diseases, including allergic rhinitis (AR); however, the interaction between the gut and respiratory tract and the role of microbes remains unclear. We investigated the gut and nasal microbiota variations between AR and control mice and their role in the bidirectional regulation of the gut-nasal axis.

Methods: We validated the OVA-induced establishment of an AR mouse model based on nasal symptoms and histopathology. The microbiota and metabolites in the feces and nasal lavage fluid were analyzed, and a correlation analysis was performed. Structural changes in the colonic and nasal mucosa were examined using electron microscopy, and ZO-1 and Claudin 1 protein expression was assessed using immunofluorescence and western blotting. RNA-seq identified changes in gene expression in the nasal mucosa. Mendelian randomization analysis was applied to exploit the causal relationship between gut microbiota, gut microbiota-derived metabolites and AR.

Results: AR mice exhibited aggravated nasal symptoms, local histological disruption, and inflammatory cell infiltration in the nasal mucosa and gut tissues, with significant changes in the microbiota and metabolites at both sites. Correlation analysis revealed that gut microbes influenced fecal and nasal lavage fluid metabolite changes and vice versa. AR mice also have impaired nasal mucosal and colonic interepithelial junctions, reduced ZO-1 and Claudin 1 expression, and upregulated immune-inflammatory pathways in the nasal mucosa.

Conclusion: The microbiota in the gut and nasal cavity interact bidirectionally, coordinating the gut-nasal axis and contributing to AR pathology. These findings provide insights for advancing AR research and management.

Background: Respiratory syncytial virus (RSV) is a leading cause of respiratory infections in infants and young children. The COVID-19 pandemic significantly disrupted global RSV epidemiology. This study aimed to investigate the impact of the pandemic on RSV epidemiology in northern Taiwan from 2018 to 2023.

Methods: We retrospectively enrolled children aged <5 years with positive RSV antigen tests from 2018 to 2023, dividing into four study periods based on the COVID-19 pandemic timeline: 2018-2019, 2020-2021, 2022, 2023.

Results: The number of RSV positive cases was 1155 in 2018-2019, 780 in 2020-2021, 784 in 2022, and 1116 in 2023. The proportion of RSV-positive children aged 2-5 years increased progressively from 23.9 % (2018-2019) to 52.0 % (2023) (P < 0.001). The mean age of infected children increased over time (P < 0.001). Among children under 2 years old, hospitalization rates declined from 82.0 % (2018-2019) to 68.1 % (2023) in subsequent intervals (P < 0.001). Compared to 2018-2019, seasonal peaks delayed by 2 months in 2020, absent in 2021, and delayed by 3 and 2 months in 2022 and 2023, respectively. The RSV seasonal peaks varied with shortened peaks during the COVID pandemic. ICU admission rates declined from 2.9 % to 1.9 % while mortality declined from 0.2 % to 0 %. Independent risk factors for severe disease included age under 3 months, bronchopulmonary dysplasia, congenital heart disease, cerebral palsy, neurodevelopmental disorders, and co-infection with Streptococcus pneumoniae.

Conclusions: The COVID-19 pandemic significantly altered the seasonality and clinical characteristics of RSV infections in northern Taiwan, likely due to the varying intensity of public health interventions.

Objectives: Vancomycin-resistant enterococcal bloodstream infections (VRE-BSIs) carry high mortality in patients with malignancy. While neutropenia is a known risk factor for mortality in patients with malignancy and BSI, its impact on the effectiveness of daptomycin and linezolid in VRE-BSI is not well defined.

Methods: We conducted a multicenter cohort study of hospitalized patients aged ≥18 years with malignancy and VRE-BSI between 2010 and 2021. Eligible patients received linezolid or high-dose daptomycin (≥8 mg/kg). Those with pneumonia or Enterococcus species other than E. faecium were excluded. Only the first VRE-BSI episode per patient was analyzed. The primary outcome was 14-day mortality, assessed using multivariable logistic regression.

Results: A total of 474 patients were included (linezolid, n = 90; daptomycin, n = 384); 128 (27.0 %) had neutropenia. The 14-day mortality was 32.9 % (156/474). Mortality was higher in neutropenic than non-neutropenic patients (45/128 [35.2 %] vs. 111/346 [32.1 %]; P = 0.005). Among neutropenic patients, mortality was 6/8 (75.0 %) with linezolid and 49/120 (40.8 %) with daptomycin; in non-neutropenic patients, mortality was 16/82 (19.5 %) and 85/264 (32.2 %), respectively. In multivariable analysis, linezolid use in neutropenic patients was associated with higher mortality (aOR 8.48; 95 % CI, 1.40-51.30; P = 0.02).

Conclusions: Neutropenia was associated with worse outcomes in patients with VRE-BSI, and linezolid-treated neutropenic patients showed higher mortality in this cohort. These findings should be interpreted cautiously given the small sample size and residual confounding. High-dose daptomycin may be considered, particularly in neutropenic patients, but confirmatory studies are needed.

Background: Interferon-gamma release assays (IGRAs) measure immune responses to pathogen-specific antigens such as tuberculosis. However, the assay hinges on a functional immune system. Whether IGRAs can be used to identify heart transplant candidates with impaired immunity and worse prognosis is not known.

Methods: From August 1st^, 2014 to August 31st^, 2018, all heart transplant candidates at a medical center in Taiwan who received an IGRA (QuantiFERON®-TB Gold In-Tube) during transplant evaluation to screen for latent tuberculosis infection were included. Inadequate immunity was defined as a response of <1 IU/ml of interferon-γ (IFN-γ) to the common mitogen in the positive control tube of the IGRA. Patients were followed until death or January 31st, 2019 for all-cause mortality and subsequent infections.

Results: A total of 103 patients were included, and 23 (22.3 %) had inadequate mitogen responses. After a median follow-up duration of 676 days (interquartile range [IQR] 387-1299), 34 (33.0 %) patients received a heart transplant and 23 (22.3 %) patients died. Forty-eight (46.6 %) patients developed infections, predominantly bacteremia (37.5 %). Those with inadequate mitogen responses had significantly higher rates of mortality (39.1 % vs. 17.5 %, p = 0.028) and infections (65.2 % vs. 41.3 %, p = 0.042). In the multivariate analysis, inadequate responses to mitogen were significantly associated with mortality and infections (hazard ratio [HR] 3.36, confidence interval [CI] 1.22-9.23, p = 0.019; HR 2.75, CI 1.18-6.40, p = 0.019).

Conclusions: Patients with heart failure and inadequate mitogen responses by IGRAs had a higher risk of mortality and infection. IGRAs may have a novel application in prognostication of heart transplant candidates.

Background: To compare diagnostic performances and accuracy of non-invasive specimens and bronchoalveolar lavage fluid (BALF) for diagnosing Pneumocystis pneumonia (PCP) in immunocompromised pneumonia patients.

Methods: A prospective study of 112 immunocompromised patients to evaluate P. jirovecii fungal loads in paired sputum and BALF from the same patients. Patients were classified as definite PCP, probable PCP, and non-PCP based on criteria blinded to qPCR results. Optimal diagnostic cut-offs were derived, and agreement between specimen types was analyzed.

Results: A BALF fungal load threshold of 2,613 DNA copies/μL demonstrated high sensitivity (82.6 %, 95 % CI: 62.9-93.0) and specificity (96.7 %, 95 % CI: 90.8-99.1) for PCP diagnosis. In sputum, a cut-off of 474 DNA copies/μL offered moderate sensitivity (65.2 %, 95 % CI: 44.9-81.2) and high specificity (89.0 %, 95 % CI: 80.9-93.9), enabling the exclusion of PCP in patients with low clinical suspicion. Fungal loads in sputum correlated well with BALF but showed greater variability in confirmed PCP cases, highlighting limitations for non-invasive diagnosis in high-risk patients.

Conclusion: Non-invasive fungal load in sputum provides a valuable tool for excluding PCP in immunocompromised pneumonia patients, potentially reducing the need for bronchoscopy.

Background: Multidrug-resistant Klebsiella pneumoniae (MDR-KP) leads global health concerns as an infectious agent due to many virulence factors, including biofilm formation. The growing urgency for alternative treatment strategies beyond antibiotics has renewed interest in bacteriophages. Pathogen evolution is dynamic and can lead to phage resistance.

Methods: Bacteriophages were isolated from environmental sources and screened against a panel of 280 MDR- K. pneumoniae clinical isolates (74 from 2018 to 2020 and 167 from 2022-23 and 39 environmental KP isolates). Phages were grouped by host range and DNA fingerprinting. Five candidate phages with unique and broad host coverage were selected for further characterization and genome sequencing.

Results: Five candidate phages exhibited diverse host range patterns, strong bacteriolytic activity and significant antibiofilm activity even at low multiplicity of infection. Whole genome sequencing analysis revealed phage KPØ6 to be a novel Taipevirus species with low intergenomic similarity to known phages, and it showed the broadest host range on isolates from the 2018-2020 panel. A significant rise in phage resistance among MDR-KP isolate panels of 2018-2020 and 2022-2023 was observed.

Conclusion: Lytic bacteriophages offer a promising alternative for tackling MDR-KP infections, especially within healthcare environments. The phages characterized in this study demonstrate strong potential for both biocontrol and therapeutic use against MDR-KP, including infections involving biofilms. However, the dynamic nature of bacterial evolution over five years reiterates the need to update phage banks.

Objectives: Diagnosing paediatric Community-Acquired Pneumonia (CAP) is challenging due to the difficulty in obtaining lung specimens. Studies suggest that the upper-airway density of Streptococcus pneumoniae is related to the risk and severity of CAP. We studied the association between S. pneumoniae and its density in the upper airways with CAP and its severity. Additionally, we examined the relationship between respiratory viral load and severe CAP.

Methods: Seven hundred fifteen children with radiologically confirmed CAP and 673 controls were enrolled over 11 years. Nasopharyngeal aspirates (NPA) were tested for 20 viruses and bacteria using semi-quantitative polymerase chain reaction (PCR). NPAs positive for S. pneumoniae were further analysed by quantitative PCR. Adjusted odds ratios (aORs) and 95 % confidence intervals (CIs) were calculated to assess the association between S. pneumoniae density and CAP and CAP severity.

Results: Fewer cases than controls were colonised with S. pneumoniae (culture: 37.6 % vs 51.9 %, p < .001; PCR: 55.3 % vs 69.1 %, p < .001), and the median density was lower (6.20 log¹⁰ copies/mL vs 6.62 log¹⁰ copies/mL, p < .001). No association was found between S. pneumoniae density and CAP severity. CAP severity was significantly associated with high Respiratory Syncytial Virus (RSV) load (aOR 2.26, 95 % CI 1.43-3.57, p < .001) or high Human Metapneumovirus (HMPV) load (aOR 4.32, 95 % CI 2.19-8.48, p < .001), adjusted by pneumococcal density, other pathogens, age, sex, comorbidities, prior antibiotics and season.

Conclusions: Detection and density of S. pneumoniae in the upper airways do not correlate with CAP presence or severity. High RSV and HMPV loads were linked to severe CAP.