Thomas Richard Rogers

Fungal pathogens and the infections they cause are notoriously understudied and underrepresented in public health surveillance programs. Recent initiatives, such as that of the Joint Programming Initiative on Anti-Microbial Resistance (JPIAMR), recognize these gaps and have supported the development of a fungal surveillance resistance network. The International Fungal Network for One-Health Resistance Surveillance: Antifungal Resistance (INFORM-AFR) network sought to enhance understanding of existing surveillance programs, with the ultimate goal of developing standardized fungal surveillance strategies that enable international comparisons. A survey was conducted involving mycology reference centers or public health institutes (n = 15) from 12 countries, each responsible for nationwide or regional surveillance programs on fungal infections or pathogens. The ongoing programs were heterogenous, not only in terms of the epidemiological focus of surveillance (pathogen vs disease based), but also in relation to the mycological procedures used (identification and antifungal susceptibility testing methods). Funding dedicated to surveillance was variable and often lacked long-term stability, resulting in suboptimal surveillance data in many centers and limiting the generation of accurate and consistent knowledge. With the expanding number of fungal disease cases and increasing reports of antifungal resistance, we strongly advocate for improved integration of fungal infections into nationwide health surveillance programs as well as international standardization.

Invasive fungal disease (IFD) is a recognised and potentially life-threatening complication of chronic graft-versus-host disease (cGVHD) and its treatment. Invasive aspergillosis (IA), most often due to the species Aspergillus fumigatus, is the leading IFD in this setting. IA can occur during the early weeks following allogeneic haematopoietic stem cell transplantation (HSCT) coinciding with profound neutropenia, but increasingly, cases of IA occur after engraftment, coinciding with the occurrence of cGVHD. Immunomodulatory treatments of cGVHD can impair innate immune responses to inhaled Aspergillus conidia, increasing the risk of developing IA. Here, in a pilot study, we present an analysis of the phenotypic characteristics (phagocytic efficiency, fungal killing, and cytokine release) of circulating monocytes derived from patients with cGVHD compared to healthy volunteers. We found that there was no statistically significant difference in their ability to phagocytose A. fumigatus conidia, and while there was a trend in their reduced ability to kill conidia, this was not significant when compared to the ability of volunteers’ monocytes to do so. Although we could not demonstrate in this small cohort of patients with cGVHD that monocytes may be a factor in the increased susceptibility to IA, further investigation of larger numbers of study subjects is warranted so that in vitro biomarkers may be developed for immune responses to Aspergillus in patients with cGVHD.

Clostridioides difficile (C. difficile), once considered a predominantly nosocomial pathogen, is increasingly implicated in community-acquired infections (CA-CDIs). This study investigates the prevalence, ribotypes, and antimicrobial susceptibility of C. difficile in Irish pork products and abattoirs, with a focus on the potential public health implications. A total of 180 retail pork products and 150 pig carcase swabs from three abattoirs were examined, alongside 30 environmental lairage samples. The C. difficile isolates were characterised through ribotyping and tested in terms of antimicrobial susceptibility. No C. difficile was isolated from the retail pork, while the carcase swabs yielded a low recovery rate (0.66%). However, the lairage areas were contaminated with C. difficile (33%), and six different ribotypes were identified, including the clinically relevant RT078. The ribotypes exhibited susceptibility to the antibiotics used to treat C. difficile infection (CDI) (fidaxomicin, vancomycin, and metronidazole) but showed resistance to tetracycline (9%) and ciprofloxacin (100%). These findings align with the international findings on antimicrobial resistance in C. difficile and suggest that strict EU food safety standards could mitigate retail pork contamination risks. Nevertheless, the environmental exposure during slaughtering and handling processes presents potential transmission risks for workers.

This meta-analysis examines the comparative diagnostic performance of polymerase chain reaction (PCR) for the diagnosis of Pneumocystis pneumonia (PCP) on different respiratory tract samples, in both human immunodeficiency virus (HIV) and non-HIV populations. A total of 55 articles met inclusion criteria, including 11 434 PCR assays on respiratory specimens from 7835 patients at risk of PCP. QUADAS-2 tool indicated low risk of bias across all studies. Using a bivariate and random-effects meta-regression analysis, the diagnostic performance of PCR against the European Organisation for Research and Treatment of Cancer–Mycoses Study Group definition of proven PCP was examined. Quantitative PCR (qPCR) on bronchoalveolar lavage fluid provided the highest pooled sensitivity of 98.7% (95% confidence interval [CI], 96.8%–99.5%), adequate specificity of 89.3% (95% CI, 84.4%–92.7%), negative likelihood ratio (LR⁻) of 0.014, and positive likelihood ratio (LR⁺) of 9.19. qPCR on induced sputum provided similarly high sensitivity of 99.0% (95% CI, 94.4%–99.3%) but a reduced specificity of 81.5% (95% CI, 72.1%–88.3%), LR⁻ of 0.024, and LR⁺ of 5.30. qPCR on upper respiratory tract samples provided lower sensitivity of 89.2% (95% CI, 71.0%–96.5%), high specificity of 90.5% (95% CI, 80.9%–95.5%), LR⁻ of 0.120, and LR⁺ of 9.34. There was no significant difference in sensitivity and specificity of PCR according to HIV status of patients. On deeper respiratory tract specimens, PCR negativity can be used to confidently exclude PCP, but PCR positivity will likely require clinical interpretation to distinguish between colonization and active infection, partially dependent on the strength of the PCR signal (indicative of fungal burden), the specimen type, and patient population tested. This graphical abstract is also available at Tidbit: https://tidbitapp.io/tidbits/pcr-on-respiratory-tract-specimens-of-immunocompromised-patients-to-diagnose-pneumocystosis-pcp-a-systematic-review-and-meta-analysis-89aa7a50-efbc-4ebb-8f20-c17d207e8d8e?utm_campaign=tidbitlinkshare&utm_source=ITP

Aspergillus fumigatus has been found to coinfect patients with severe SARS-CoV-2 virus infection, leading to COVID-19-associated pulmonary aspergillosis (CAPA). The CAPA all-cause mortality rate is approximately 50% and may be complicated by azole resistance. Genomic epidemiology can help shed light on the genetics of A. fumigatus causing CAPA, including the prevalence of resistance-associated alleles. We present a population genomic analysis of 21 CAPA isolates from four European countries with these isolates compared against 240 non-CAPA A. fumigatus isolates from a wider population. Bioinformatic analysis and antifungal susceptibility testing were performed to quantify resistance and identify possible genetically encoded azole-resistant mechanisms. The phylogenetic analysis of the 21 CAPA isolates showed that they were representative of the wider A. fumigatus population with no obvious clustering. The prevalence of phenotypic azole resistance in CAPA was 14.3% (n = 3/21); all three CAPA isolates contained a known resistance-associated cyp51A polymorphism. The relatively high prevalence of azole resistance alleles that we document poses a probable threat to treatment success rates, warranting the enhanced surveillance of A. fumigatus genotypes in these patients. Furthermore, potential changes to antifungal first-line treatment guidelines may be needed to improve patient outcomes when CAPA is suspected.

This overview of reviews (i.e., an umbrella review) is designed to reappraise the validity of systematic reviews (SRs) and meta-analyses related to the performance of Aspergillus PCR tests for the diagnosis of invasive aspergillosis in immunocompromised patients. The methodological quality of the SRs was assessed using the AMSTAR-2 checklist; the quality of the evidence (QOE) within each SR was appraised following the GRADE approach. Eight out of 12 SRs were evaluated for qualitative and quantitative assessment. Five SRs evaluated Aspergillus PCR on bronchoalveolar lavage fluid (BAL) and three on blood specimens. The eight SRs included 167 overlapping reports (59 evaluating PCR in blood specimens, and 108 in BAL), based on 107 individual primary studies (98 trials with a cohort design, and 19 with a case−control design). In BAL specimens, the mean sensitivity and specificity ranged from 0.57 to 0.91, and from 0.92 to 0.97, respectively (QOE: very low to low). In blood specimens (whole blood or serum), the mean sensitivity ranged from 0.57 to 0.84, and the mean specificity from 0.58 to 0.95 (QOE: low to moderate). Across studies, only a low proportion of AMSTAR-2 critical domains were unmet (1.8%), demonstrating a high quality of methodological assessment. Conclusions. Based on the overall methodological assessment of the reviews included, on average we can have high confidence in the quality of results generated by the SRs.

The aim of this study was to characterize C. difficile isolates from the farm, abattoir, and retail outlets in Ireland in terms of ribotype and antibiotic resistance (vancomycin, erythromycin, metronidazole, moxifloxacin, clindamycin, and rifampicin) using PCR and E-test methods, respectively. The most common ribotype in all stages of the food chain (including retail foods) was 078 and a variant (RT078/4). Less commonly reported (014/0, 002/1, 049, and 205) and novel (RT530, 547, and 683) ribotypes were also detected, but at lower frequencies. Approximately 72% (26/36 tested) of the isolates tested were resistant to at least one antibiotic, with the majority of these (65%; 17/26) displaying a multi-drug (three to five antibiotics) resistant phenotype. It was concluded that ribotype 078, a hypervirulent strain commonly associated with C. difficile infection (CDI) in Ireland, was the most frequent ribotype along the food chain, resistance to clinically important antibiotics was common in C. difficile food chain isolates, and there was no relationship between ribotype and antibiotic resistance profile.

Aspergillus fumigatus is the most commonly isolated fungus in chronic lung diseases, with a prevalence of up to 60% in cystic fibrosis patients. Despite this, the impact of A. fumigatus colonisation on lung epithelia has not been thoroughly explored. We investigated the influence of A. fumigatus supernatants and the secondary metabolite, gliotoxin, on human bronchial epithelial cells (HBE) and CF bronchial epithelial (CFBE) cells. CFBE (F508del CFBE41o⁻) and HBE (16HBE14o⁻) trans-epithelial electrical resistance (TEER) was measured following exposure to A. fumigatus reference and clinical isolates, a gliotoxin-deficient mutant (ΔgliG) and pure gliotoxin. The impact on tight junction (TJ) proteins, zonula occludens-1 (ZO-1) and junctional adhesion molecule-A (JAM-A) were determined by western blot analysis and confocal microscopy. A. fumigatus conidia and supernatants caused significant disruption to CFBE and HBE TJs within 24 h. Supernatants from later cultures (72 h) caused the greatest disruption while ΔgliG mutant supernatants caused no disruption to TJ integrity. The ZO-1 and JAM-A distribution in epithelial monolayers were altered by A. fumigatus supernatants but not by ΔgliG supernatants, suggesting that gliotoxin is involved in this process. The fact that ΔgliG conidia were still capable of disrupting epithelial monolayers indicates that direct cell–cell contact also plays a role, independently of gliotoxin production. Gliotoxin is capable of disrupting TJ integrity which has the potential to contribute to airway damage, and enhance microbial invasion and sensitisation in CF.

The study demonstrates the improved sensitivity of the Ultra compared with the Xpert, particularly in smear negative TB disease, for both pulmonary and extrapulmonary samples in a low TB incidence setting. Cycle threshold (Ct) value for both assays was found to positively correlate with time to TB culture positivity, suggesting that Ct and semiquantitative results could be used as indicators of sample MTBC bacillary burden, and thus, perhaps, of transmission potential.

The increasing incidence and changing epidemiology of invasive fungal infections continue to present many challenges to their effective management. The repertoire of antifungal drugs available for treatment is still limited although there are new antifungals on the horizon. Successful treatment of invasive mycoses is dependent on a mix of pathogen-, host- and antifungal drug-related factors. Laboratories need to be adept at detection of fungal pathogens in clinical samples in order to effectively guide treatment by identifying isolates with acquired drug resistance. While there are international guidelines on how to conduct in vitro antifungal susceptibility testing, these are not performed as widely as for bacterial pathogens. Furthermore, fungi generally are recovered in cultures more slowly than bacteria, and often cannot be cultured in the laboratory. Therefore, non-culture-based methods, including molecular tests, to detect fungi in clinical specimens are increasingly important in patient management and are becoming more reliable as technology improves. Molecular methods can also be used for detection of target gene mutations or other mechanisms that predict antifungal drug resistance. This review addresses acquired antifungal drug resistance in the principal human fungal pathogens and describes known resistance mechanisms and what in-house and commercial tools are available for their detection. It is emphasized that this approach should be complementary to culture-based susceptibility testing, given the range of mutations, resistance mechanisms and target genes that may be present in clinical isolates, but may not be included in current molecular assays.