Canadian Journal of Infectious Diseases & Medical Microbiology最新文献

Chronic wounds and prosthetic joint infections are difficult to treat and are associated with a high burden of disease and economic cost. The rise of antibiotic resistance and the understanding of biofilm formation has inflamed an already challenging situation. Bacteriophage therapy has been used throughout the last century to treat bacterial infections. However, in the last 10 years, there has been a resurgence in phage therapy as a novel innovative treatment for nonhealing wounds. This mini systemic review assesses relevant clinical studies, case series and trials over 5 years associated with safety, treatment and success rates of phage therapy concerning nonhealing and prosthetic joint infections. A search of PubMed, Web of Science, Cochrane and Clinical Trials.gov databases resulted in 3151 studies, 27 met the criteria, and a total of 152 bacterial infections were treated from 130 individuals. Most common pathogen isolated in wounds was P. aeruginosa, and S. aureus was mostly associated with prosthetic joint infections. Treatment modalities differed across studies, adverse effects were limited, and success rate was deemed to be 91%.

Background: Burn patients are more likely to get healthcare-associated infections (HAIs). The current study aimed to investigate the characteristics of HAI and mortality risk factors among burn patients admitted to a tertiary center in Iran. Methods: A retrospective study was conducted in 2021 on burn patients who developed HAI after hospitalization in a tertiary center in Ahvaz, Iran. The records of patients admitted and managed between March 2019 and March 2020 were reviewed. Statistical analysis was carried out using IBM SPSS Version 26, with p < 0.05 considered statistically significant. Results: Of the 1,659 admitted patients, 395 (23.8%) developed HAI during the study period. After excluding patients with incomplete medical records and those with fungal or viral infections, 363 patients remained. The majority of these cases occurred in male patients. The most common type of HAI was burn wound infection (56.2%). Patients were mainly affected by Gram-negative bacteria, Pseudomonas aeruginosa (39.7%), while the most common Gram-positive bacteria was Staphylococcus epidermididis (9.6%). The most common antibiotic resistance among P. aeruginosa-infected patients was reported against imipenem, followed by gentamicin and ciprofloxacin; however, the mentioned organism was mainly sensitive to colistin. Gender, age, bloodstream infection (BSI), ventilator-associated infection (VAI), ICU admission, and total burned surface area (TBSA) resulted in 3.585, 1.028, 2.222, 7.469, 5.278-, and 1.031 times higher mortality rates, respectively. Conclusion: Female gender, advanced age, BSI, VAI, and ICU admission are risk factors for HAI. These findings emphasize the need for focused infection prevention and management to improve high-risk burn patient survival.

Malarial and bacterial coinfections in low-income countries are a serious cause of morbidity and mortality, necessitating coadministration of antibiotics and antimalarials. This study investigated the relationship between malaria infection and bacterial drug resistance in malaria and nonmalaria patients on consultation at the Dschang Regional Hospital. A follow-up study was carried out from October 2020 to December 2021 on 127 malaria and 174 nonmalaria patients having enteric infections. Clinical and haematological parameters were measured using standard methods. CD4 and CD8 cells were determined using flow cytometry. Enteric bacteria pathogens were isolated from stool, and antimicrobial and antimalarial profiles were determined using agar diffusion and microdilution methods, respectively. Significant reduction of RBCs, WBCs, CD4, CD8, granulocytes, monocytes and platelets was seen in coinfected patients compared to monoinfected participants (p ≤ 0.0491). E. coli was the main pathogenic bacteria isolated from the digestive tract of coinfected patients (40.63%) and monoinfected patients (59.37%). E. coli showed a high level of resistance to AMX (57.69%) and CDA (61.54%) in coinfected patients compared to 55.26% and 41.67%, respectively, in monoinfected patients. Quinine (53[50.00%]; 6[42.86%]) presented a minimal inhibitory concentration (MIC) of 32 μg/mL on the bacteria isolates from coinfected and monoinfected patients, respectively, while Artemether 89 (83.96%), Maloxine 5 (3.94%) and Surquina 250 (39.37%) presented a MIC of 64 μg/mL on bacterial isolates of coinfected and monoinfected patients. E. coli showed high resistance against AKI (45.93%), AMX (43.75%) and ERY (59.37%) in malaria patients who were under antimalarial drugs compared to malaria patients who were not under malaria drugs (29.68%, 34.37% and 32.81%, respectively). This study highlights that antimalarial drugs might certainly have an influence on the acquisition and emergence of bacterial resistance in the case of malaria bacterial coinfection, and therefore, adequate management and planning effective control programmes might certainly go a long way to reduce the rate of morbidity and mortality.

Background: The presence of bacteria in the blood of healthy individuals remains controversial. This study explored the comprehensive bacterial profiles and specific biomarkers in different components of healthy Chinese blood donors. Methods: A total of 5230 whole blood (WB) specimens were collected. Among them, 5200 random samples were pooled into 26 mixed samples for bacterial profile analysis. The remaining 30 random samples were divided into 4 groups based on components: WB, plasma, red blood cells (RBCs), and buffy coat (BC). Subsequently, the amplicons of the bacterial 16S rDNA V3-V4 fragments were sequenced to measure the diversity and composition of the bacteria using next-generation sequencing. Results: The bacterial DNAs in the blood primarily originated from the Proteobacteria phylum. A total of 301 species of bacterial DNA were found in blood specimens, with 46 species being present among all groups. A significantly higher abundance of bacterial DNA was found in the plasma and RBCs compared to those in BC and WB. However, the plasma and RBC groups showed significantly higher species diversity and richness compared to the BC and WB groups. In addition, the WB group had a significantly different community structure and composition compared to the plasma and RBC groups but was similar to the BC group. Conclusion: The presence of bacterial DNA fragments was confirmed in blood from healthy Chinese donors. The bacterial DNA fragments enriched in plasma showed the highest diversity, followed by RBC, WB, and BC. These results provide a foundation for further research on the microbiome in the blood of healthy individuals.

[This corrects the article DOI: 10.1155/2001/547516.].

Objective: Bloodstream infections (BSIs) caused by Listeria monocytogenes are linked to high mortality of the patients. Case-specific details related to this disease and causative strains in different districts remain to be characterized.

Methods: In this study, medical data of BSIs admitted to West China Hospital from October 2017 to March 2023 were retrieved from the hospital information system. The in vitro antimicrobial susceptibility testing and whole-genome sequencing were performed for L. monocytogenes strains isolated from blood specimens. The genetic relationship of these strains with those in public databases was also analyzed.

Result: The in-hospital mortality of L. monocytogenes BSIs was 25.7% (9/35). The changes in consciousness and elevated serum C-reactive protein (CRP) level were found to be the differential factors of L. monocytogenes BSIs (P < 0.05). All the 27 strains studied were susceptible to ampicillin, meropenem, and erythromycin. Only 22.2% of them were susceptible to trimethoprim-sulfamethoxazole. The Listeria pathogenicity islands 1 (LIPI-1), truncated LIPI-2, and multiple virulence-related genes outside the LIPIs were determined from these strains. Also, 12 sequence types (STs) and 12 clonal complexes (CCs) were identified and classified into clonal lineages I (9/27, 33.3%) and lineages II (18/27, 66.7%), demonstrating genetic differences with the strains in the database. ST451/CC11 (5/27, 18.5%) and ST8/CC8 (4/27, 14.8%) were the common genotypes.

Conclusions: The consciousness change and elevated serum CRP level were found to be the differential factors of L. monocytogenes BSIs. Considering the high virulence of the strains, it is needed to pay more attention to the dissemination of the predominant genotype.

Exploring drug susceptibility is a critical endeavor in the scientific community, setting the stage for advancements in understanding and combating various pathogens. Candida kefyr has emerged as a significant pathogen, particularly affecting immunocompromised individuals with hematologic malignancies and HIV/AIDS conditions. This study aimed to assess the antifungal susceptibility profile of Candida kefyr isolates obtained from clinical samples and dairy products. A total of 134 Candida kefyr yeast isolates were retrieved from three distinct groups: (1) healthy individuals (n = 41), (2) patients (n = 24) including hematologic malignancy (n = 9), HIV/AIDS (n = 7), and diabetes (n = 8), (3) dairy products (milk, yogurt, and cheese, n = 69) stored at -70°C in the Shiraz University of Medical Science. All Candida kefyr isolates were previously identified using conventional and molecular methods. Susceptibility to antifungal drugs, including caspofungin, fluconazole, itraconazole, voriconazole, and amphotericin B, was determined using the microdilution method following CLSI-M27-A3 protocols, with results interpreted according to CLSI-M27-S4 guidelines. The study emphasizes the clear variation in antifungal susceptibility testing of Candida kefyr strains when compared across different groups, including patients, healthy people, and dairy products. According to the results, across all groups, a high minimum inhibitory concentration of fluconazole is evident, and healthy individuals show the highest minimum inhibitory concentration geometric means (4.0681). Also, 79.1% of the isolates were wild type to amphotericin B, with the lowest minimum inhibitory concentration compared to other antifungals tested. This suggests that amphotericin B was more effective against Candida kefyr. These findings showed fewer susceptibilities of Candida kefyr to both triazole and echinocandin classes of antifungal agents. Additionally, it is noteworthy that individuals without medical conditions exhibited higher minimum inhibitory concentration rates to these antifungal agents in comparison to those with underlying health conditions. Consequently, timely diagnosis and appropriate therapeutic interventions emerge as imperative in the effective management of candidiasis cases.

Salmonella is the main bacterial pathogen that causes foodborne disease, particularly in developing countries. Nontyphoidal Salmonella (NTS) include Enteritidis and Typhimurium as the most prevalent strains which are one of the significant causes of acute gastroenteritis in children. Therefore, identifying the most predominant serovars, types of common contaminated food, and paying attention to their antibiotic resistance are the main factors in the prevention and control strategy of salmonellosis. This study was undertaken to evaluate the prevalence rate of serovars, the biofilm formation, antimicrobial resistance (AMR) status, and phenotypic virulence factors of Salmonella strains isolated from diarrhea samples in some cities of Iran. A total of 40 (10.41%) Salmonella isolates were recovered from 384 diarrhea samples processed and the most common serovar was Salmonella serovar Typhimurium (82.5). Also, all isolates belonging to serovar Typhimurium showed more virulence factors compared to other serovars. The isolates showed a high resistance rate to ampicillin (95%) and nalidixic acid (87.5%), while a low resistance rate was found for chloramphenicol (2.5%). Moreover, significant variances in the capacity of biofilm formation were found between different Salmonella serotypes. The resistance of NTS to extant choice drugs is a potential public health problem. Constant monitoring of AMR pattern and virulence profile of NTS serovars is suggested for the prevention of salmonellosis in humans.

Klebsiella pneumoniae is a pathogen that commonly causes hospital-acquired infections. Bacterial biofilms are structured bacterial communities that adhere to the surface of objects or biological tissues. In this study, we investigated the genome homology and biofilm formation capacity of ESBL-producing K. pneumoniae. Thirty ESBL-producing K. pneumoniae isolates from 25 inpatients at Ruijin Hospital, Shanghai, were subjected to pulsed-field gel electrophoresis (PFGE) to estimate genomic relatedness. Based on the chromosomal DNA patterns we obtained, we identified 21 PFGE profiles from the 30 isolates, eight of which had high homology indicating that they may have genetic relationships and/or potential clonal advantages within the hospital. Approximately 84% (21/25) of the clinical patients had a history of surgery, urinary tract catheterization, and/or arteriovenous intubation, all of which may have increased the risk for nosocomial infections. Biofilms were observed in 73% (22/30) of the isolates and that strains did not express type 3 fimbriae did not have biofilm formation capacity. Above findings indicated that a high percentage of ESBL-producing K. pneumoniae isolates formed biofilms in vitro and even though two strains with cut-off of PFGE reached 100% similarity, they generated biofilms differently. Besides, the variability in biofilm formation ability may be correlated with the expression of type 3 fimbriae. Thus, we next screened four ESBL-producing K. pneumoniae isolates (Kpn5, Kpn7, Kpn11, and Kpn16) with high homology and significant differences in biofilm formation using PFGE molecular typing, colony morphology, and crystal violet tests. Kpn7 and Kpn16 had stronger biofilm formation abilities compared with Kpn5 and Kpn11. The ability of above four ESBL-producing K. pneumoniae isolates to agglutinate in a mannose-resistant manner or in a mannose-sensitive manner, as well as RNA sequencing-based transcriptome results, showed that type 3 fimbriae play a significant role in biofilm formation. In contrast, type 1 fimbriae were downregulated during biofilm formation. Further research is needed to fully understand the regulatory mechanisms which underlie these processes.

The emergence of hypervirulent strains of Acinetobacter baumannii poses a significant threat in intensive care units (ICU). This study aimed to molecularly characterize hypervirulent A. baumannii strains isolated from ICU patients with respiratory infections. Six strains were isolated from ICU patients over one month. Isolates were identified by phenotypic characterization biochemical properties and 16s RNA sequencing. Antibiotic susceptibility testing was conducted followed by resistance genes detection by PCR. MLST, and PFGE were employed to analyse clonal relationships among strains. Plasmid replicon typing and plasmid transmission frequencies were determined. The isolated strains exhibited diverse clinical manifestations, including acute respiratory distress syndrome (ARDS). Antibiotic susceptibility testing revealed multidrug-resistance phenotype. Molecular analysis revealed a complex genetic landscape of antibiotic resistance genes, including ESBLs and carbapenemases, as well as virulence genes such as ompA, csuE, and exoS. The multiple sequence types indicating genetic diversity among the strains as ST1512, ST622, and ST149 (each type two isolates). Plasmid characterization revealed the presence of diverse replicon types associated with multidrug resistance. This study provides comprehensive insights into the phenotypic, molecular, and epidemiological characteristics of hypervirulent A. baumannii outbark in ICU.