Journal of medical microbiology最新文献

Introduction. Bloodstream infections (BSIs) are one of the most serious infections investigated by microbiologists. However, the time to detect a BSI fails to meet the rapidity required to inform clinical decisions in real time.Gap Statement. Blood culture (BC) is considered the gold standard for diagnosing bloodstream infections. However, the time to blood culture positivity can be lengthy. Underpinning this is the reliance on bacteria replicating to a high concentration, which is necessary for the detection using routine blood culture systems. To improve the diagnosis and management of patients with BSIs, more sensitive detection methods are required.Aim. The study aimed to answer key questions addressing the delay in BSI detection and whether the time to BSI detection could be expedited using a Scattered Light Integrated Collection (SLIC) device.Methodology. A proof-of-concept study was conducted to compare the time to positivity (TTP) of Gram-negative BCs flagging positive on BacT/ALERT with an SLIC device. An SLIC device was utilized to compare the TTP of the most prevalent BSI pathogens derived from nutrient broth and BC, the influence of bacterial load on TTP and the TTP directly from whole blood. Additionally, the overall turnaround time (TAT) of SLIC was compared with that of a standard hospital workflow.Results. Most pathogens tested took significantly longer to replicate when derived from BC than from nutrient medium. The median TTP of Gram-negative BC on BacT/ALERT was 13.56 h with a median bacterial load of 6.4×10⁹ c.f.u. ml^-1. All pathogens (7/7) derived from BC at a concentration of 10⁵ c.f.u. ml^-1 were detectable in under 70 min on SLIC. Decreasing Escherichia coli BC concentration from 10⁵ to 10² c.f.u. ml^-1 increased the TTP of SLIC from 15 to 85 min. Direct BSI detection from whole blood on SLIC demonstrated a 76% reduction in TAT when compared with the standard hospital workflow.Conclusion. An SLIC device significantly reduced the TTP of common BSI pathogens. The application of this technology could have a major impact on the detection and management of BSI.

Introduction. Shiga toxin-producing Escherichia coli (STEC) infections are of public health concern as STEC can cause large national foodborne outbreaks of severe gastrointestinal disease, particularly in the young and elderly. In recent years, the implementation of PCR by diagnostic microbiology laboratories has improved the detection of STEC, and there has been an increase in notifications of cases of non-O157 STEC. However, the extent this increase in caseload can be attributed to the improved detection by PCR, or a true increase in non-O157 STEC infections, is unknown.Gap Statement. Epidemiological and microbiological data and analyses describing the trends in non-O157 STEC in England since the implementation of PCR are limited.Aim. Demographic, microbiological and clinical characteristics of non-O157 STEC from 8 years (2016-2023) of laboratory surveillance data were analysed to understand the recent trends in non-O157 serotypes and the incidence of disease in England.Methodology. All human isolates of STEC non-O157 detected between 2016 and 2023 were extracted from the laboratory surveillance system. Microbiological data were analysed and linked to clinical outcomes.Results. There was an almost 10-fold increase in diagnoses of non-O157 STEC from 2016 (n=297) to 2023 (n=2341). A total of 9378 isolates of non-O157 STEC were detected, comprising 338 different serotypes, and were linked to 9311 individuals. A higher proportion of non-O157 STEC cases were female (56%) and aged between 20 and 39 years (27%). The most common non-O157 serotypes were O26:H11 (16%), O146:H21 (12%), O91:H14 (11%), O128:H2 (6%), O145:H28 (5%) and O103:H2 (4%). STEC O26:H11 was more frequently reported in under 5s than any other age group (38%), whereas the other common serotypes were more frequently isolated from adults. Stx2a, which has been associated with greater disease severity, was detected in 18% of cases. Where clinical details were available, 27% of non-O157 cases were admitted to the hospital and 6% developed HUS. Cases of STEC O145:H28 reported a higher rate of hospitalisation than other non-O157 STEC cases. The serotypes most likely to be associated with progression to HUS were O26:H11 (9%) and O145:H28 (7%). STEC harbouring stx2f (19%), stx2a (11%) and stx2d (11%) were most frequently isolated from cases with HUS.Conclusion. The implementation of widespread PCR testing in England has facilitated better surveillance of STEC non-O157, with respect to establishing the true incidence and burden of disease of non-O157 STEC and monitoring the emergence of highly virulent strains.

Introduction. Ocular fungal infections are pathologies of slow progression, occurring mainly in the cornea, but can also affect the entire structure of the eyeball. The main aetiological agents are species of the genera Candida and Fusarium. Both diagnosis and treatment require speed and effectiveness. However, the currently available therapy basically consists of the use of azoles and polyenes, known for their low penetration into the ocular tissue and the associated toxicity.Hypothesis. Thus, new strategies to combat these infections are needed, such as the development of new antifungals or the use of associations.Aim. Thus, the compound PH151, derived from a promising class of 8-hydroxyquinolines, and natamycin, amphotericin B (AMB) and voriconazole (VRC), the main antifungals used in ocular antifungal therapy, were considered against Candida spp. and Fusarium spp.Methodology. The MICs of compound PH151 ranged from 1.0 to 16.0 µg ml^-1, according to CLSI protocols.Results. The association of PH151 with AMB and VRC showed a synergistic effect for more than 50% of the strains tested.Conclusion. Both the compound alone and its association (VRC-AMB-PH151) demonstrated promising potential as an antifungal agent in ocular infections, since the evaluated ocular toxicity profile was positive and the compounds presented low toxicity.

Introduction. Infections by carbapenemase-producing Pseudomonas aeruginosa (CP-Pa) are concerning due to limited treatment options. The emergence of multidrug-resistant (MDR) high-risk clones is an essential driver in the global rise of CP-Pa.Hypothesis/Gap Statement. Insights into the molecular epidemiology of CP-Pa are crucial to understanding its clinical and public health impact. Despite the low incidence of infections in Norway, global spread requires an understanding of regional dissemination patterns.Aim. This study aimed to investigate the phenotypic and genotypic characteristics of CP-Pa isolates in Norway and molecular epidemiology by utilizing available metadata.Methodology. The study collection comprised all verified CP-Pa isolated in Norway from 2006 to 2022 (n=67) obtained from clinical (75%; n=50) or screening samples (22%; n=15) or had no available information (3%; n=2). Phenotypic analyses included antimicrobial susceptibility testing against clinically relevant antipseudomonal antibiotics and comparative testing for carbapenemase production using three different methods (β-CARBA, IMI/IMD gradient test and Coris O.K.N.V.I RESIST-5). Whole-genome sequencing was performed to identify virulence factors, resistance determinants and genomic relatedness.Results. The isolates were categorized as MDR (n=39) encoding Verona integron-encoded metallo-β-lactamase (VIM) (n=28), New Delhi metallo-β-lactamase (NDM) (n=6), imipenemase metallo-β-lactamase (IMP) (n=4) or Guiana extended spectrum metallo-β-lactamase (n=1) carbapenemases or extensively drug-resistant (XDR; n=28) encoding VIM (n=11), NDM (n=9) or IMP (n=8) carbapenemases. CP-Pa numbers ranged from 1 to 7 annually, peaking at 17 in 2022. Most isolates (n=64) were associated with international travel or hospitalization abroad. Phylogenetic analyses identified nine clusters of closely related genomes, with one suspected case of domestic patient-to-patient transmission. Among 21 detected sequence types, several were global high-risk clones, including ST235 (n=12), ST111 (n=9), ST773 (n=9), ST253 (n=3), ST357 (n=3), ST395 (n=3), ST823 (n=3), ST233 (n=2), ST654 (n=2), ST260 (n=1) and ST308 (n=1), covering 72% of the Norwegian isolates. ST1047 (IMP-1) and ST773 (NDM-1) were associated with Ukrainian war victims. Carbapenemase detection rates for phenotypic tests were 88% (β-CARBA), 91% (IMI/IMD) and 94% (Coris) in our collection.Conclusion. The study highlights the low incidence yet high genomic diversity of CP-Pa in Norway and the dominance of high-risk clones linked to imports, contributing to the high proportion of XDR.

Introduction. Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans who have been in close contact with infected pigs or contaminated pork-derived products. There is currently no consensus on the universal virulence factors or markers that can differentiate pathogenic from non-pathogenic or commensal S. suis isolates.Gap statement. A diagnostic tool for serotyping and pathotyping of S. suis is required for active public health surveillance and the One-Health approach.Aim. To improve the former multiplex PCR to serotyping all 29 recognized 'true' serotypes and distinguish pathogenic pathotypes using primers targeting the capsule and ROK pathogenic marker genes.Methodology. Four sets of multiplex PCRs were modified and improved to detect all 29 recognized serotypes of S. suis and distinguish their pathogenic pathotypes using the ROK gene.Results. This multiplex PCR allowed for the simultaneous amplification of S. suis-specific, serotype-specific and pathogenic pathotypes from the DNA of each serotype in each reaction. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of the pathogenic ROK marker genes were 84.7% (625/738), 96.4% (423/439), 67.6% (202/299), 81.4% (423/520) and 92.7% (202/218), respectively. There was a significant (P-value <0.001), high positive likelihood ratio [2.9 with 2.5-3.5 of 95% confidence interval (CI)] and a significant odds ratio (55.1 with 31.6-95.9 of 95 % CI), which indicated that the ROK gene could be used as the pathogenic pathotype marker. No cross-reactions were observed with other bacterial species.Conclusion. This modified multiplex PCR was able to distinguish 29 well-known serotypes and predicted the pathogenic pathotypes of S. suis isolates from humans and pigs in a single assay. It is useful for One-Health surveillance of human and pig isolates of S. suis.

Introduction. Alcohol abuse can lead to significant cardiac injury, resulting in Alcoholic heart disease (AHD). The interplay between cardiac health and gut microbiota composition in the context of alcohol consumption is not well understood.Hypothesis. Shen Song Yang Xin (SSYX) capsule and amiodarone are common drugs used to treat alcoholic heart disease, but little is known about their microbial regulatory mechanisms in alcoholic heart disease.Aim. To investigate the effects of SSYX and amiodarone on cardiac injury and gut microbiota composition in a rat model of AHD induced by alcohol consumption.Methodology. We evaluated body weight, cardiac function, changes in gut morphology, and gut microbiota composition to assess the effects of SSYX and amiodarone on AHD.Results. Alcohol consumption significantly reduced body weight and aggravated cardiac fibrosis. However, SSYX attenuated fibrosis and improved cardiac function. SSYX also improved intestinal morphological changes caused by chronic alcoholism and activated the expression of ZO-1 and occludin, which are important in maintaining intestinal barrier function. The gut microbiota composition was altered in rats with AHD, with an increase in Actinobacteria abundance. Both SSYX and amiodarone affected the gut microbiota composition, and their effects were positively correlated. SSYX plays a protective role against heart injury caused by alcohol consumption. It improves cardiac function, intestinal morphological changes and gut microbiota composition.Conclusion. SSYX and amiodarone may have potential therapeutic options for AHD. Actinobacteria/Firmicutes ratio and the abundance of Christensenellaceae R7 group, norank_flachnospiraceae and Roseburia may serve as potential biomarkers for detecting alcoholic heart disease.

Introduction. Fungal infections caused by yeast have increased in recent decades, becoming a major threat to public health.Hypothesis/Gap Statement. Antifungal therapy represents a challenging problem because, in addition to presenting many side effects, fungal resistance has been increasing in recent years. As a result, the search for new therapeutic agents has advanced with the use of new technologies such as nanoparticles (NPs).Aim. Synthesize, characterize and evaluate the antifungal potential of naringenin (NAR)-stabilized silver NPs.Methodology. The biosynthesis of NPs was stabilized using the NAR molecule and an aqueous solution of silver nitrate. The characterization of silver nanoparticles (AgNPs) was performed using different methods, which include UV-visible spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy, zeta potential measurements and Fourier transform infrared (FTIR) spectroscopy. Antifungal activity was evaluated against clinical isolates of Candida albicans by determining the MIC and the minimum fungicidal concentration (MFC).Results. The AgNP NAR showed a colloidal appearance with an average size of 14.71 nm and zeta potential measured at -33.3 mV, indicating a highly stable suspension. XRD analysis confirmed the crystal structure. FTIR spectra showed the presence of several functional groups of plant compounds, which play an important role in the coating and bioreduction processes. The antifungal activity against C. albicans showed an MIC of 3.55 µg ml^-1 and an MFC of 7.1 µg ml^-1. According to the growth kinetic assay in 12 h, there was a reduction of ~50% (<3 log10). Furthermore, AgNP NAR did not show mutagenic potential.Conclusion. The AgNP NAR obtained presented ideal characteristics for biomedical applications, good stability and promising antimicrobial activity.

Staphylococcus epidermidis is frequently isolated during prosthetic joint infections (PJIs). Unlike Staphylococcus aureus, its internalization and persistence within cells are controversial. We aimed to determine whether internalization is involved in the pathophysiology of S. epidermidis PJIs. Adhesion and internalization of S. epidermidis PJI isolates have been studied using an in vitro model. Despite similar adhesion levels to the S. aureus SH1000 reference strain, S. epidermidis isolates had a low internalization in osteoblasts, synoviocytes and endothelial cells. Internalization of S. epidermidis is strain- and cell-type dependent. Our results do not support S. epidermidis internalization as a key factor in PJIs.

Introduction. Apolipoprotein E (ApoE), especially the ApoE4 isotype, is suggested to influence the severity of respiratory viral infections; however, this association is still unclear.Hypothesis. The presence of allele ε4 impacts the development of flu-like syndromes.Aim. This study aimed to evaluate the impact of the Apo E4 isoform on the severity and duration of flu-like syndromes, including the coronavirus disease COVID-19.Methodology. This study comprised 280 individuals presenting flu-like symptoms, all genotyped for ApoE isoforms. Data were collected on clinical course, comorbidities, nutritional status, biochemical and inflammatory markers, SARS-CoV-2 reverse transcription PCR results and disease severity (mild, moderate or severe) according to the World Health Organization criteria. The individuals were analysed as a whole and within subgroups based on the SARS-CoV-2-positive (COVID-19 group) or SARS-CoV-2-negative (flu-like syndrome group) test.Results. The frequency of the ε4 allele was similar across the whole population and in both the COVID-19 and flu-like syndrome subgroups (17 and 18%, respectively). No differences were seen in sex, age range, self-reported skin colour, body mass index (BMI), number of comorbidities, vaccination status, biochemical, cytokine and lipid profiles (except for total cholesterol) in the flu-like group when ε4 allele carriers and non-carriers were compared. In the COVID-19 group, the ε4 allele did not correlate with disease severity or duration, number of comorbidities or inflammatory biomarkers. While gender distribution was equal in the overall COVID-19 population, male gender strongly correlated with COVID-19 severity. Multivariate analysis showed that older individuals, male gender, higher BMI and the presence of comorbidities were linked to increased chances of developing moderate and severe disease. IL-4 was the only factor found to reduce the risk of severe COVID-19.Conclusion. The presence of one ɛ4 allele showed no association with the duration and severity of flu-like syndromes, including COVID-19. Nonetheless, SARS-CoV-2-positive individuals tend to be older men with a higher BMI and a tendency to be overweight or with obesity. Regarding COVID-19 severity, BMI, male sex and the number of associated comorbidities were the factors that increased the chance of developing a more severe form of COVID-19.

Introduction. Diagnosis of uveitis is challenging due to the multitude of possible pathogenies. Identifying infectious and non-infectious uveitis is of great clinical significance. Recently, metagenomic next-generation sequencing (mNGS) was used to detect infectious and non-infectious uveitis, but its efficacy has not been widely evaluated.Hypothesis. Compared with routine diagnostic tests (RDTs), mNGS is more effective in identifying infectious and non-infectious uveitis.Aim. To describe the microbiological diagnostic performance of mNGS in detecting infectious and non-infectious uveitis.Methodology. Patients with suspected infectious uveitis of uncertain pathogenesis were tested by mNGS and RDTs. Infectious and non-infectious uveitis were grouped according to the final diagnosis based on comprehensive analysis of the test results and the effect of therapy. The test results were used to assess the performance of mNGS in actual clinical practice.Results. Fifty-eight cases were enrolled in this project, including 32 cases of infectious uveitis and 26 cases of non-infectious uveitis. The sensitivity of mNGS was 96.88%, which was much higher than that of RDTs. The detected pathogenic micro-organisms included bacteria, fungi, viruses, Toxoplasma gondii and Bartonella. Consequently, mNGS showed a high negative predictive value (NPV) of 94.74%, indicating that an mNGS negative should be a true negative result most of the time, but a low positive predictive value (PPV) of 79.49%.Conclusions. mNGS showed extremely high sensitivity but low specificity, which increased the detection rate of infectious uveitis pathogens but might result in false positives. The excellent NPV suggested that the identification of non-infectious uveitis is of considerable clinical importance.