Canadian Journal of Infectious Diseases & Medical Microbiology最新文献

Background: Occult hepatitis B virus infection (OBI) refers to the detection of HBV DNA in blood or liver tissue in individuals who test negative for hepatitis B surface antigen (HBsAg), excluding the early phase of acute HBV infection. This hidden form of infection represents a substantial but frequently underestimated risk to blood transfusion safety, particularly in settings with limited resources. In Ethiopia and other low-income countries, routine screening of blood donors often depends solely on HBsAg tests, which may overlook symptom-free carriers with low viral loads. This study was conducted to estimate the prevalence of OBI among HBsAg-negative blood donors and to assess its potential contribution to undetected HBV transmission in central Ethiopia.

Methods: Five hundred and eighty-two plasma samples from HBsAg-negative donors were analyzed. Initial screening for anti-Hepatitis B core antibodies (anti-HBc) was carried out using an enzyme-linked immunosorbent assay (ELISA). Samples that tested positive for anti-HBc were then analyzed for HBV DNA using the Abbott m2000 automated real-time polymerase chain reaction (RT-PCR) system. At the same time, information on sociodemographic characteristics and potential clinical risk factors for HBV exposure was obtained through structured questionnaires. Data were analyzed with SPSS Version 21, and statistical significance was considered at a p value of less than 0.05.

Results: In this study, screening of 582 blood donors who were negative for HBsAg revealed that 135 (23.2%) donors, or nearly one-quarter, showed evidence of previous HBV exposure through anti-HBc reactivity. Subsequent molecular testing (PCR) identified a small proportion of these individuals carrying HBV DNA, confirming occult infection. Viral loads in all confirmed cases were low. Older donors, particularly those above 35 years of age, demonstrated a markedly higher rate of anti-HBc positivity. Overall, the occurrence of OBI was estimated at 1.7%, or approximately 17 cases for every 1000 blood donations, highlighting a critical gap in the current HBV screening protocol.

Conclusion: The findings demonstrate that a notable number of blood donors in central Ethiopia carry occult HBV infection, equivalent to 17 cases per 1000 donations. This indicates a concealed yet important risk of HBV transmission through blood transfusion. These results underscore the need to enhance donor screening protocols by incorporating both anti-HBc testing and nucleic acid testing (NAT) to improve transfusion safety and prevent the spread of undetected HBV.

Pulmonary infections remain a significant global health burden, particularly in immunocompromised individuals and patients with chronic respiratory or systemic diseases. Conventional microbiological tests (CMTs), though widely used, often have limited sensitivity and delayed results, especially in polymicrobial or atypical infections. This study evaluated the diagnostic performance of nanopore targeted sequencing (NTS) in 284 patients with suspected lower respiratory tract infections at Chifeng Municipal Hospital, using CMTs and clinical diagnosis as references. NTS demonstrated markedly higher sensitivity (91.85%) compared to CMTs (74.81%), with substantial improvements in detecting fungal (81.7%) and mixed infections (99.65%). A total of 259 pathogens were detected. Among them, bacteria were the most frequently identified pathogens (69.5%), followed by fungi (15.44%) and viruses (14.28%). Pathogen distribution varied by clinical subgroup, such as community-acquired pneumonia and chronic obstructive pulmonary disease, reflecting infection heterogeneity. Patients with hypertension (HBP) showed a higher incidence of fungal and mixed infections than non-HBP patients. NTS was particularly effective in detecting opportunistic pathogens in the HBP group, suggesting an association between cardiovascular comorbidity and altered pathogen susceptibility.

Background: To date, there is a lack of research on the clinical characteristics and cytokine profiles in children with influenza A following COVID-19 infection.

Methods: Children with influenza A lower respiratory tract infection who were hospitalized in the Department of Pediatrics of the Affiliated Hospital of Southwest Medical University from March 15 to April 15, 2023, were divided into mild and severe groups according to their symptoms, followed up on the COVID-19 infection status by telephone, and selected those who had been infected with COVID-19 for comparison of clinical characteristics and cytokines.

Results: An analysis of influenza A case in children with prior SARS-CoV-2 infection revealed that the proportion of previous infection was significantly higher in the severe group compared to the mild group. Univariate analysis indicated significant differences between the two groups in the incidence of convulsions, concurrent or secondary bacterial infections, white blood cell (WBC) count, lymphocyte percentage (L%), neutrophil percentage (N%), and interferon-induced protein-10 (IP-10) (all P < 0.05). Binary logistic regression and receiver operating characteristic (ROC) curve analysis identified IP-10 and WBC as independent risk factors for severe influenza A following SARS-CoV-2 infection, the combination of IP-10 and WBC demonstrated high diagnostic accuracy for disease severity.

Conclusion: IP-10 and WBC count serve as diagnostic biomarkers for severe influenza infection following SARS-CoV-2 infection, and their combination significantly enhances diagnostic performance.

Background: Most evidence on ventilator-associated pneumonia (VAP)-related and ventilator-associated tracheobronchitis (VAT)-related mortality comes from general ICU settings, with limited data on critically ill cancer patients. This study aimed to characterize the microbiological profile and resistance patterns in an oncology hospital and evaluate their impact on 14-day mortality.

Methods: We conducted a retrospective analysis of VAP and VAT cases in an oncology ICU in Brazil (Jan-Dec 2024), assessing bacterial frequency, multidrug-resistant organisms (MDRO), and mortality. Multivariate analysis was used to identify the variables significantly associated with mortality.

Results: Among 85 ICU patients, tracheobronchitis was more frequent (59%) than pneumonia (41%). Most were male (61%) with a median age of 62 years and had solid tumors (85%), mainly in the lungs and neck. Of 109 samples, P. aeruginosa (27%), K. pneumoniae (20%), and S. maltophilia (17%) were the most common pathogens. MDRO was particularly high in A. baumannii (82%). Overall, 14-day mortality was 55%. MDR was not associated with mortality (p = 0.3), but VAP (OR 4.20, p = 0.004) and infections with positive blood culture (OR 5.38, p = 0.023) were independently associated with mortality.

Conclusion: This study provides valuable insights into the microbiological profile of patients with VAP and VAT in an oncological ICU and its impact on mortality. Mortality was not associated with MDR, possibly reflecting the high baseline risk from underlying conditions. However, patients with positive blood cultures had significantly higher mortality, suggesting a more invasive disease.

Purpose: Although studies have described the clinical characteristics of norovirus enteritis (NoVE) associated with convulsions, research on its molecular epidemiology remains limited. Therefore, this study aimed to investigate both the clinical manifestations and genotypic features of NoVE complicated by convulsions.

Methods: NoVE children admitted to our hospital between November 2021 and May 2022 were divided into NoVE complicated with convulsion group and NoVE group. Then, we screened the risk factors of NoVE complicated with convulsion based on multivariate regression analysis. The stool samples were collected, followed by amplification of VP1 sequences of GI and GII and phylogenetic analysis of VP1 in both groups.

Results: Logistic regression analysis showed that elevated serum CK-MB levels and fever were independent risk factors for convulsions in NoVE patients, while a lower frequency of diarrhea was an independent protective factor. GII.3 genotype was merely detected in 12 NoVE samples (14.81%) and was detected in 5 (15.19%) NoVE with convulsion samples. The GII.4 genotype was detected in 28 (84.85%) samples of the NoVE with convulsion group and 69 (85.19%) samples from the NoVE group.

Conclusions: Elevated serum CK-MB concentration, fever, and frequency of diarrhea were independent influencing factors for NoVE complicated by convulsions.

Although the number of yearly occurrences of malaria has significantly decreased in recent years, malaria remains one of the major public health issues in Cameroon. A deeper understanding of how the various alleles of the malaria parasite's genes move in the field between the two sexes and between seasons, as well as knowledge of malaria parasite genetic diversity in different malaria-endemic locations, would be necessary for the development of a successful malaria elimination strategy. This study aimed to evaluate the genetic diversity of the Msp1 and Msp2 genes of Plasmodium falciparum in Bamenda, North West Region of Cameroon, identify the alleles of the Msp1 and Msp2 genes that are associated with severe malaria, and determine how the alleles of the Msp1 and Msp2 genes are distributed between sexes and seasons. Blood samples were collected on Whatman's filter paper from those who had malaria caused by P. falciparum as determined by microscopy and rapid diagnostic tests. DNA from P. falciparum was isolated using the Chelex technique. Using nested PCR, the Msp1 Block 2 and Msp2 Block 3 genes were genotyped. The Msp1 Block 2 gene was genotyped in a total of 281 samples. For Msp1 Block 2 genes, all the family-specific alleles were present (RO33, K1, and MAD20). At 44.7% frequency, RO33 was the most prevalent allele, while K1 was linked to severe malaria. The Msp2 Block 3 gene was genotyped in a total of 194 samples. For Msp2 Block 3 genes, all of the family-specific alleles were present (3D7 and FC27). With 56.7%, 3D7 was the most prevalent. There was an association between the Msp2 Block 3 gene alleles and sex (χ² = 8.856, p = 0.012). No Msp1 Block 2 or Msp2 Block 3 allele was more prevalent in any specific season. These results would be useful in assessing the efficacy of malaria prevention measures implemented in Bamenda as well as in selecting and designing malaria prevention measures that are suitable for implementation in Bamenda, North West Region of Cameroon.

Introduction: Diarrheal diseases remain a major public health concern, causing over two million deaths annually in developing countries. Diarrheagenic Escherichia coli, particularly enterotoxigenic strains, are a leading cause of gastrointestinal infections in humans and animals. Poultry can act as a reservoir for pathogenic E. coli, facilitating transmission to humans via contaminated food or water. This study aimed to isolate and characterize bacteriophages targeting E. coli pathotypes from poultry, with the goal of controlling gastrointestinal infections and reducing the risk of zoonotic transmission.

Methods: ETEC strains were isolated from poultry with colibacillosis and confirmed by LT and ST toxin genes. Their antibiotic resistance and biofilm formation were evaluated. Bacteriophages were isolated from wastewater, and their host range, morphology, growth characteristics, lytic activity, and stability under different temperatures and pH were assessed.

Result: The isolated ETEC strain exhibited a multidrug-resistant phenotype and strong biofilm formation. The bacteriophage was highly specific for this strain, showing no lysis of other bacteria, and was classified as belonging to the Autographiviridae family by TEM analysis. One-step growth experiments revealed a latent period of 0-10 min and a burst size of 93 PFU/cell. Lytic activity was effective at MOIs of 10 and 100, and the phage remained stable under typical environmental and physiological conditions, suggesting its potential applicability in poultry.

Conclusion: The isolated phage demonstrates high specificity, lytic activity, and stability, indicating its potential as an alternative or adjunct to antibiotics for controlling MDR ETEC in poultry. Further studies are warranted to evaluate its safety and efficacy under in vivo conditions.

Acinetobacter baumannii is a critical nosocomial pathogen recognized by the WHO as a top-priority threat due to its extensive drug resistance, particularly in carbapenem-resistant Acinetobacter baumannii (CRAB) strains. According to recent CDC reports, CRAB is one of the most urgent causes of hospital-acquired infections, driving longer hospital stays, higher costs, and mortality. This pathogen employs multiple resistance mechanisms, including efflux pumps, porins like OmpA, making it highly difficult to treat. Resistance is further shaped by β-lactamases, integrons, and mobile genetic elements. The emergence of MDR, XDR, and PDR strains signals the looming postantibiotic era, where conventional therapies are increasingly ineffective. While several reviews have provided in-depth analyses of individual mechanisms and some comprehensive overviews, this work provides a broad overview of resistance strategies and genetic determinants, including tet(A/B), cmlA, and mdfA. Importantly, we also highlight emerging alternatives such as novel emergent phage therapy (NEPT), which proactively counters antiphage resistance and nanoparticles (CNPs), which resensitize resistant isolates and enhance antibiotic efficacy. By combining mechanistic insights with emerging interventions, this review provides a comprehensive perspective on CRAB resistance and highlights research priorities for mitigating its global threat.

Background: Corynebacterium striatum (C. striatum) is an emerging opportunistic pathogen. Its role in pathogenicity can be difficult to determine and requires careful analysis of laboratory results and clinical symptoms. This research aims to investigate the clinical characteristics and risk factors of C. striatum infection in normally sterile body fluids and urine.

Methods: A retrospective study was conducted in the Affiliated Hospital of North Sichuan Medical College in China. The study included 50 patients infected with C. striatum and 70 cases with non-C. striatum infections from January 2018 to December 2023. Clinical data were analyzed, and independent risk factors for C. striatum infection were identified using chi-square tests and multivariate logistic regression.

Results: Patients in the C. striatum group were primarily distributed in the intensive care unit (ICU), neurosurgery, and nephrology departments. Most had a history of severe underlying diseases (80%), invasive procedures (84%), and antibiotic use (74%). The highest detection rate of C. striatum was 0.45% in 2018. Compared with the non-C. striatum infection group, the C. striatum infection group showed a longer duration of invasive procedures, more days of antibiotic use, and a higher number of antibiotics used (p < 0.05). Logistic regression analysis identified them as independent risk factors for C. striatum infection in normally sterile body fluids and urine.

Conclusion: Patients with severe conditions requiring multiple invasive procedures and prolonged treatment with multiple antibiotics may be more susceptible to C. striatum infection in normally sterile body fluids and urine. Clinicians should be aware of these risk factors to help prevent and manage C. striatum infections more effectively.