Journal of medical microbiology最新文献

Background. Achromobacter xylosoxidans and Pseudomonas aeruginosa are two pathogens that cause persistent airway infections in individuals with cystic fibrosis (CF). The persistence of P. aeruginosa is partly due to a high capacity to form biofilms and the ability to exert antagonism against other bacteria. Loss of microbial diversity in conjunction with chronic P. aeruginosa colonization is strongly correlated with low lung function in CF. A. xylosoxidans and P. aeruginosa are frequently co-isolated in CF airway cultures. This study aims to investigate the reciprocal effects on growth inhibition and biofilm formation between P. aeruginosa and A. xylosoxidans in vitro.Method. Six isolates of A. xylosoxidans, isolated from three CF patients in early and late stages of a chronic infection, were cultured together with a CF isolate of P. aeruginosa. Biofilm formation was assessed using a microtiter assay and crystal violet staining. Quantitative PCR was used to quantify species proportions in biofilms. Growth curves were performed to compare planktonic growth rates.Results. Three A. xylosoxidans isolates, all of which were from early-stage infections, inhibited biofilm formation of P. aeruginosa. The inhibition was concentration-dependent and required the interaction of live bacteria during the early stages of biofilm development. The inhibitory effect was not caused by nutrient depletion of the planktonic cells. The selected A. xylosoxidans isolate had a stronger capacity to adhere to plastic surfaces compared to the P. aeruginosa isolate.Conclusions . A. xylosoxidans can inhibit P. aeruginosa biofilm formation in vitro. The observed effect requires active interactions between live cells during the attachment stage of biofilm formation, possibly due to differences in adhesion capacity.

The COVID-19 pandemic has significantly increased the complexity of managing burn patients, who are particularly susceptible to bacterial co-infections due to their compromised skin barriers and immune dysregulation. Toxin-producing bacteria, such as Staphylococcus aureus and Pseudomonas aeruginosa, pose severe risks by producing virulence factors that impair immune function, delay wound healing and exacerbate systemic inflammation. These challenges are amplified in the presence of SARS-CoV-2, as the viral-induced immune dysregulation and cytokine storms worsen clinical outcomes, leading to higher rates of morbidity and mortality. This review explores the interplay between viral and bacterial infections in burn patients during the COVID-19 pandemic, focusing on the role of bacterial toxins, including superantigens from S. aureus and exotoxins from P. aeruginosa in driving hyperinflammatory responses. These synergistic effects complicate treatment by increasing the likelihood of systemic complications, prolonged hospital stays and MDR infections. To address these challenges, we discuss innovative therapeutic strategies, including endotoxin adsorption therapy to reduce systemic inflammation, immunomodulatory treatments to control cytokine storms and bacteriophage therapy for targeting MDR pathogens. Advanced wound care techniques and rapid diagnostic tools, such as CRISPR-based molecular assays, are highlighted as essential for timely and effective intervention. This review underscores the urgent need for integrated approaches that combine targeted diagnostics, advanced therapeutics and robust infection control measures. These insights aim to improve outcomes for burn patients co-infected with bacterial pathogens and SARS-CoV-2, offering valuable guidance for future pandemic preparedness and burn care protocols.

Introduction . Campylobacter jejuni is the leading cause of bacterial gastroenteritis worldwide. Infections with C. jejuni can result in two different diarrhoeal manifestations in humans: watery diarrhoea or bloody/inflammatory diarrhoea.Hypothesis/Gap Statement. Currently, little is known about C. jejuni and/or host factors associated with the elicitation of these two distinct diarrhoeal manifestations. We hypothesize that these factors may include growth and metabolic trait differences between C. jejuni strains associated with watery diarrhoea and bloody/inflammatory diarrhoea.Aim. Using C. jejuni strains with a defined diarrhoeal manifestation in the neonatal piglet model, we aimed to assess differences in temperature-dependent growth rates, motility, biofilm production and carbon utilization between diarrhoeal manifestation groups.Methodology. Strains were initially assessed for 192 different carbon sources using phenotypic microarrays followed by specific carbon utilization, growth, motility and biofilm assays at 37 and/or 42 °C.Results. We found that at 37 °C, watery diarrhoea-associated C. jejuni strains grew significantly faster compared with bloody/inflammatory diarrhoea-associated C. jejuni strains. However, there was no significant growth difference at 42 °C between the groups, due to bloody/inflammatory diarrhoea-associated strains growing faster at 42 °C compared with 37 °C. Additionally, at 37 °C, we found that l-fucose utilization was significantly higher among watery diarrhoea-associated strains, while l-glutamine utilization was significantly higher among bloody/inflammatory diarrhoea-associated strains.Conclusion. The results indicate there are distinct metabolic adaptations between watery and/or bloody/inflammatory diarrhoea-associated C. jejuni strains particularly at 37 °C, which may be one of the factors associated with differing diarrhoeal manifestations.

Introduction. Nosocomial infections, particularly those caused by Gram-negative bacilli, indeed pose significant challenges in healthcare settings. Hospital staff can act as carriers of these infections, potentially transmitting them to patients and colleagues. Propolis, a natural resinous substance collected by honeybees, has shown promising antibacterial properties against various microorganisms, including Gram-negative bacteria like Escherichia coli and Klebsiella pneumoniae.Hypothesis/Gap Statement. Despite the documented antibacterial properties of propolis, limited research has evaluated its efficacy against clinical isolates from healthcare workers, particularly in Iran.Aim. To evaluate the in vitro effect of propolis on K. pneumoniae and E. coli isolated from the nose and nails of hospital personnel in Qazvin.Methodology. Fifty Gram-negative bacilli were isolated from the nose and nails of hospital personnel in Qazvin. An antibiotic sensitivity test was conducted using the disk diffusion method based on CLSI 2024 guidelines for various antibiotics. The most common isolated strain was analysed using enterobacterial repetitive consensus PCR (ERIC-PCR). Finally, the microbroth dilution method was used to assess the antibacterial effect of propolis on the isolated strains.Results. The most frequent pathogens were K. pneumoniae (66%) followed by E. coli (34%). Most of the isolates were sensitive to the majority of antibiotics tested, and the highest antibiotic resistance was observed in trimethoprim/sulfamethoxazole (55%), ceftazidime (32%) and tetracycline (26%). Extended-spectrum beta-lactamase production was found in 10% of isolates of all Gram-negative bacteria. Additionally, 24% of the strains were multidrug-resistant. ERIC-PCR analysis revealed high genetic diversity among K. pneumoniae strains, which were the most common strains isolated from personnel. The MIC of propolis for both K. pneumoniae and E. coli was 5%, and the minimum bactericidal concentration was 10% after culturing 100 µl on Mueller-Hinton agar.Conclusion. The present study showed that the isolates from the nose and nails of hospital personnel may pose a serious issue in the field of public health. These findings suggest that Iranian bee propolis has medicinal value as a natural product and was identified as an antimicrobial substance with positive effects on bacterial strains isolated from hospital personnel.

Antimicrobial resistance (AMR) is a real and current threat to public health, yet the role of vaccines in combating this crisis remains underutilized and under-recognized. This meeting report summarizes key insights from a multidisciplinary workshop convened by the Microbiology Society in February 2025, as part of the Knocking Out AMR initiative, bringing together 21 expert stakeholders across academia, industry, clinical and veterinary sectors and policy. The workshop explored how vaccines can reduce the burden of AMR by preventing infections, limiting antibiotic use and slowing resistance development. Discussions highlighted the need to strengthen the evidence base for vaccine-mediated AMR reduction, address policy and regulatory barriers and incentivize public-private collaboration in vaccine development. Participants called for AMR impact to be formally recognized in vaccine labelling and national immunization strategies, and for greater integration of vaccines into AMR action plans. The workshop also underscored the importance of One Health approaches, investment in research for both human and animal vaccines and the role of the microbiology community in driving change.

Introduction. Since 2005, the leading cause of death for western chimpanzees (Pan troglodytes verus) at Tacugama Chimpanzee Sanctuary (TCS) in Sierra Leone has been epizootic neurologic and gastroenteric syndrome (ENGS), associated with the bacterium Sarcina troglodytae (family Clostridiaceae).Gap Statement. The prevalence of S. troglodytae at TCS in clinically normal chimpanzees and the environment remains unknown, as does its distribution in other captive and wild chimpanzee populations and their environments across Africa.Aim. The aim of this study was to determine the distribution and prevalence of Sarcina bacteria in sanctuary and wild chimpanzee populations across Africa and to identify demographic and ecological risk factors for S. troglodytae in chimpanzees and the environment.Methodology. We conducted a prospective, multi-season epidemiological investigation of S. troglodytae in chimpanzees and the environment at TCS and a parallel study at a sanctuary in the Republic of Congo. We also describe the results of surveys of chimpanzees at a sanctuary in Uganda and wild chimpanzee populations in Sierra Leone and Uganda for S. troglodytae. In total, we tested 637 chimpanzee and environmental samples using a species-specific PCR for S. troglodytae and a pan-Sarcina PCR.Results. S. troglodytae was more prevalent in chimpanzees at TCS (n=60) during the dry season (96.7%) than during the rainy season (55.2%). Soil was the most common environmental source of the bacterium (54% dry season vs. 4.8% rainy season). Notably, we did not detect S. troglodytae in faecal samples from sanctuary chimpanzees in the Republic of Congo (n=79) or in wild chimpanzees in Sierra Leone (n=18). We did detect the bacterium in East African chimpanzees (n=84) but at low prevalence (2.6%-10.9%). In contrast, we found the genus Sarcina to be ubiquitous in all chimpanzee populations with a higher prevalence in sanctuary chimpanzees (93.1%-100%) than in wild chimpanzees (66.7%-68.4%).Conclusion. S. troglodytae is markedly more prevalent at TCS, the only location affected by ENGS, than at any other location tested, and soil is a likely reservoir of S. troglodytae. These findings strengthen the association between S. troglodytae and ENGS and have implications for sanctuary management and conservation of western chimpanzees.

Introduction. Mycoplasma genitalium, a small and slow-growing bacterium, has gained notoriety due to rapidly increasing rates of antibiotic resistance.Gap Statement. M. genitalium is difficult to culture, limiting efforts to understand its biology and the mechanisms of antimicrobial resistance.Aim. To understand factors that influence success in primary isolation of M. genitalium from clinical samples.Methodology. Neat urine or swabs (high vaginal and anal, in universal transport medium) were collected from patients with confirmed or suspected M. genitalium infections attending the Melbourne Sexual Health Centre. The specimens were stored at -80 °C prior to laboratory analysis. Initial diagnosis was by transcription-mediated amplification (TMA) assay, and samples subsequently testing positive by quantitative PCR (qPCR) were washed twice and inoculated into Vero cell monolayers with a selective antibiotic mixture (cycloheximide and Thayer-Martin Medium I). Cultures were incubated at 37 °C with 5% CO₂ for 8 weeks and observed daily, with qPCR used to monitor growth.Results. In total, 127 TMA-positive samples were subjected to qPCR, and M. genitalium genomic DNA (gDNA) was detected in 53.5% (68/127) of these samples. An isolate was obtained from 26.5% (18/68) of the gDNA-positive samples following co-culture with Vero cells. The isolation rate varied between sample types, with growth detected in 12.5% (3/24) of the high vaginal swabs and 37.5% (15/40) of the urine samples. No isolates were obtained from anal swabs. The proportion with a successful culture was influenced by the initial M. genitalium load in the sample, which translated into the inoculum size for the Vero cell monolayer. Isolation was unsuccessful with low inoculum (<2,000 genome equivalents, geq), partially successful (13.3%) with a moderate inoculum (2,500-9,500 geq) and highly successful (100%) in samples with a high inoculum (>10,000 geq).Conclusion. The initial bacterial load emerged as a critical determinant of isolation success. This emphasizes the importance of optimizing sample collection and M. genitalium isolation procedures.

Introduction. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS for rapid identification of risk group 3 (RG3) bacteria is impeded by the following two main limitations: (a) equipment and maintenance costs for instruments placed within containment and (b) lack of a validated inactivation protocol to move RG3 material to a lower containment level. A validated inactivation method would improve operations of public health laboratories by allowing safe triage of potential RG3 agents. Albeit a validated, zero-risk inactivation protocol is unlikely, scientific interrogation of methods to identify and mitigate procedural biosafety risks is vital for institutional risk assessment.Gap. To investigate the effect of a standard MALDI-TOF chemical extraction, hypothesized to alter cells, allowing passage through a filter and maintaining ability to replicate, this study paired visualization using a scanning electron microscope (SEM) with extended viability testing.Aim. This work is intended to support risk assessments for the removal of material from a containment laboratory for MALDI-TOF MS.Methodology. A standard set of Bacillus cereus and Bacillus anthracis vegetative and spore preparations was treated with a formic acid:acetonitrile extraction, with or without filtration, and plated on five types of media to monitor growth over 14 days. SEM images were taken of treated and untreated preparations, prior, during and after filtration across two filters. Reference beads provided accurate pore size measurements.Results. SEM demonstrated no difference in treated and untreated cells but did indicate the ineffectiveness of cellulose filters compared to PVDF filters. Growth was observed in preparations that did not include PVDF filtration, whereas all preparations (n=60) that included PVDF filtration were 100% non-viable. Although non-viability was observed, an important finding was the passage of 0.262 and 0.173 µm microspheres through the 0.1 µm PVDF filter. Growth of unfiltered preparations was detected between 1 and 7 days.Conclusions. This investigation demonstrates the value of interrogating materials used for bacterial inactivation, highlighting significant issues in the application of filters for exclusion purposes. Visual examination via SEM was key to providing evidence towards a low-risk inactivation method. These findings, with an understanding of limitations identified herein, can be used to inform risk assessments for the removal of RG3 bacteria from containment.