Epidemiología de las micosis invasoras: un paisaje en continuo cambio

Bioaerosol emission characteristics and potential risks during composting: Focus on pathogens and antimicrobial resistance

In this study, we analyzed bioaerosol emission characteristics and potential risks of antimicrobial resistance (AMR) during composting using the impaction culture method and metagenomic sequencing. The results showed that the highly saturated water vapor in the emission gas mitigated particulate matter emission during the thermophilic period. About the bioaerosols, the airborne aerobic bacterial emissions were suppressed as composting enters the mature period, and the airborne fungi are usually present as single-cell or small-cell aggregates (< 3.3 µm). In addition, the microbial community structure in bioaerosols was stable and independent of composting time. Most importantly, the PM2.5 in bioaerosols contained large amounts of antibiotic resistance genes (ARGs), potential pathogens, and multidrug resistant pathogens, which were diverse and present in high concentrations. Among them, ARGs concentrations encoding 21 antibiotics ranged from - 4.50 to 0.70 ppm/m3 (Log10 ARGs). Among the 89 potential human pathogens detected, Escherichia coli, Salmonella enterica, Klebsiella pneumoniae, and Staphylococcus aureus were the only culturable potentially multidrug resistant pathogens carrying multiple ARGs encoding resistance at high concentrations (- 0.57 to 1.15 ppm/m3 (Log10 ARGs)), and were more likely to persist and multiply in oligotrophic environments. Our findings indicate that composting technology can transfer AMR from solid compost to gas phase and increase the risk of AMR transmission.

A Rare Case of Invasive Central Nervous System Aspergillus niger in a Previously Immunocompetent Patient After Corticosteroid Treatment for COVID-19

Aspergillus is a ubiquitous saprophyte found in air, soil, and organic matter. Humans inhale the spore form of the fungus, but manifestations of the disease are typically predominantly seen in immunocompromised patients. Invasive central nervous system (CNS) aspergillosis is even more uncommon, and epidemiological data is sparse, particularly in immunocompetent patients. We report the case of a 67-year-old previously immunocompetent female with no known comorbidities who was treated with corticosteroids for COVID-19 one month prior to admission for altered mental status (AMS). Subsequent imaging and biopsy demonstrated invasive CNS Aspergillus niger. Though a rare cause of AMS in immunocompetent patients, this report draws attention to the detrimental immunosuppressive effects of corticosteroid therapy in COVID-19.

A Case of Fungemia Caused by Postoperative Chronic Lumbar Intervertebral Disc Infection

Postoperative surgical site infection is one of the serious postoperative complications of spine surgery, especially fungal infections. Late-stage surgical site fungal infections often lack typical clinical symptoms and have a variable clinical presentation. In this case, the patient was a senior patient with usually only tolerable pain and discomfort, which was detected 2 years after the first surgery. Such cases are even rarer for fungal bloodstream infections caused by delayed postoperative chronic fungal osteomyelitis and deserve further study for early identification and intervention to minimize harm.

Retinoids in Fungal Infections: From Bench to Bedside

Retinoids-a class of chemical compounds derived from vitamin A or chemically related to it-are used especially in dermatology, oncohematology and infectious diseases. It has been shown that retinoids-from their first generation-exert a potent antimicrobial activity against a wide range of pathogens, including bacteria, fungi and viruses. In this review, we summarize current evidence on retinoids' efficacy as antifungal agents. Studies were identified by searching electronic databases (MEDLINE, EMBASE, PubMed, Cochrane, Trials.gov) and reference lists of respective articles from 1946 to today. Only articles published in the English language were included. A total of thirty-nine articles were found according to the criteria. In this regard, to date, In vitro and In vivo studies have demonstrated the efficacy of retinoids against a broad-spectrum of human opportunistic fungal pathogens, including yeast fungi that normally colonize the skin and mucosal surfaces of humans such as Candida spp., Rhodotorula mucilaginosa and Malassezia furfur, as well as environmental moulds such as Aspergillus spp., Fonsecae monofora and many species of dermatophytes associated with fungal infections both in humans and animals. Notwithstanding a lack of double-blind clinical trials, the efficacy, tolerability and safety profile of retinoids have been demonstrated against localized and systemic fungal infections.

COVID-19-associated invasive pulmonary aspergillosis in a tertiary care center in Mexico City

Invasive pulmonary aspergillosis (IPA) is a severe infection caused by aspergillus sp. that usually develops in patients with severe immunosuppression. IPA has been recently described in critically ill COVID-19 patients (termed as COVID-associated pulmonary aspergillosis, or CAPA) that are otherwise immunocompetent. In order to describe the characteristics of patients with CAPA, we conducted a retrospective cohort study in a tertiary care center in Mexico City. We included all patients with confirmed COVID-19 admitted to the intensive care unit that had serum or bronchoalveolar lavage galactomannan measurements. We used the criteria proposed by Koehler et al. to establish the diagnosis of CAPA. Main outcomes were the need for invasive mechanical ventilation (IMV) and in-hospital mortality. Out of a total of 83 hospitalized patients with COVID-19 in the ICU, 16 (19.3%) met the criteria for CAPA. All patients diagnosed with CAPA required IMV whereas only 84% of the patients in the non-IPA group needed this intervention (P = 0.09). In the IPA group, 31% (n = 5) of the patients died, compared to 13% (n = 9) in the non-CAPA group (P = 0.08). We conclude that CAPA is a frequent co-infection in critically ill COVID-19 patients and is associated with a high mortality rate. The timely diagnosis and treatment of IPA in these patients is likely to improve their outcome.

LAY SUMMARY

We studied the characteristics of patients with COVID-19-associated invasive pulmonary aspergillosis (CAPA). Patients with CAPA tended to need invasive mechanical ventilation more frequently and to have a higher mortality rate. Adequate resources for its management can improve their outcome.

Isolation of Candida auris in large hospitals in the Autonomous Community of Valencia; population-based study (2013-2017)

BACKGROUND

Candida auris is an emerging multidrug-resistant and highly virulent yeast that spreads easily among patients.

AIMS

To describe the characteristics of candidemia caused by C. auris in the southeast of Spain (Autonomous Community of Valencia - ACV) through a 5-year population-based study.

METHODS

An analysis of all the episodes of candidemia diagnosed in the ACV, with approximately 4,500,000 inhabitants, during 2013-2017, was done. Data were obtained from the Epidemiological Surveillance Valencian Network, a network that collects all the microbiological data from the hospitals in the study region.

RESULTS

Based on the records, 1.9% of the isolates recovered from the positive blood cultures (corresponding to 1789 patients) were yeasts. This implies an annual rate of 7.09 cases/100,000 inhabitants. Of the 23 yeast species isolated, Candida albicans was the most frequent (37.3%), showing a higher frequency than Candida parapsilosis (28.4%) and Candida glabrata (15.6%) (p<0.0001). It is remarkable the emergence of C. auris during 2016 and 2017, as this species became the fourth more prevalent in 2016 (9.2%), and the third in 2017 (15.7%). Fungemia was more common in hospitals with >500 beds (63.3% versus 36.7% in small hospitals) (p<0.0001), and C. auris was mostly isolated in large hospitals (8.5% versus 0.3%); its incidence was higher in autumn and among the age group of 65-84 years.

CONCLUSIONS

The information about the local epidemiology of candidemia is essential in order to decide the best empirical treatment approach. This study reports the novel presence of C. auris in large hospitals. This pathogen has usually resistance to several antifungals and causes severe fungemia, so the results of this work reveal the need to monitor the presence of this species systematically.

Prevalence and Antifungal Susceptibility of Pathogenic Yeasts in China: A 10-Year Retrospective Study in a Teaching Hospital

To determine the dynamic changes of pathogenic yeast prevalence and antifungal susceptibility patterns in tertiary hospitals in China, we analyzed 527 yeast isolates preserved in the Research Center for Medical Mycology at Peking University, Beijing, China, between Jan 2010 and Dec 2019 and correctly identified 19 yeast species by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and ribosomal DNA sequencing. Antifungal susceptibility testing was performed following a Sensititre YeastOne colorimetric microdilution panel with nine clinically available antifungals. The Clinical and Laboratory Standards Institute (CLSI)-approved standard M27-A3 (S4) and newly revised clinical breakpoints or species-specific and method-specific epidemiological cutoff values were used for the interpretation of susceptibility test data. In this study, although Candida albicans was the predominant single species, non-C. albicans species constituted >50% of isolates in 6 out of 10 years, and more rare species were present in the recent 5 years. The non-C. albicans species identified most frequently were Candida parapsilosis sensu stricto, Candida tropicalis, and Candida glabrata. The prevalence of fluconazole and voriconazole resistance in the C. parapsilosis sensu stricto population was <3%, but C. tropicalis exhibited decreased susceptibility to fluconazole (42, 57.5%) and voriconazole (31, 42.5%), and 22 (30.1%) C. tropicalis isolates exhibited wild-type minimum inhibitory concentrations (MICs) to posaconazole. Furthermore, fluconazole and voriconazole cross-resistance prevalence in C. tropicalis was 19 (26.1%). The overall prevalence of fluconazole resistance in the C. glabrata population was 14 (26.9%), and prevalence of isolates exhibiting voriconazole non-wild-type MICs was 33 (63.5%). High-level echinocandin resistance was mainly observed in C. glabrata, and the prevalence rates of isolate resistance to anidulafungin, micafungin, and caspofungin were 5 (9.6%), 5 (9.6%), and 4 (7.7%), respectively. Moreover, one C. glabrata isolate showed multidrug resistant to azoles, echinocandins, and flucytosine. Overall, the 10-year surveillance study showed the increasing prevalence of non-C. albicans species over time; the emergence of azole resistance in C. tropicalis and multidrug resistance in C. glabrata over the years reinforced the need for epidemiological surveillance and monitoring.

Candida albicans Adaptation on Simulated Human Body Fluids under Different pH

Candida albicans remains the most problematic of all Candida species, causing severe infections. Adaptation to different human body niches, such oral and urinary tracts, has been shown to be essential for survival and critical for virulence of C. albicans. Thus, the present work aimed to study the behaviour of C. albicans on simulated human body fluids (artificial saliva and urine) at different values of pH (pH 5.8 and 7) by determining its ability to develop two of the most important virulence factors: biofilms and filamentous forms. Under this study, it was demonstrated that C. albicans was able to grow as free cells and to develop biofilm communities composed of multiple cell types (yeast and elongated hyphal cells) on both simulated human body fluids and under different pH. It was interesting to note that the pH had little impact on C. albicans planktonic and biofilm growth, despite influencing the development of filamentous shapes in artificial saliva and urine. So, it was possible to infer that C. albicans presents a high plasticity and adaptability to different human body fluids, namely saliva and urine. These can be the justification for the high number of oral and urinary candidiasis in the whole world.

Application of 2'-OMethylRNA' Antisense Oligomer to Control Candida albicans EFG1 Virulence Determinant

Antisense oligomers and their analogs have been successfully utilized to silence gene expression for the treatment of many human diseases; however, the control of yeast’s virulence determinants has never been exploited before. In this sense, this work is based on the key hypothesis that if a pathogen’s genetic sequence is a determinant of virulence, it will be possible to synthesize a nucleic acid mimic based on antisense therapy (AST) that will bind to the mRNA produced, blocking its translation into protein and, consequently, reducing the pathogen virulence phenotype. EFG1 is an important determinant of virulence that is involved in the regulation of the Candida albicans switch from yeast to filamentous form. Thus, our main goal was to design and synthesize an antisense oligonucleotide (ASO) targeting the EFG1 mRNA and to validate its in vitro applicability. The results show that the anti-EFG1 2′-OMethylRNA (2′OMe) oligomer was able to significantly reduce the levels of EFG1 gene expression and of Efg1p protein translation (both approximately 60%), as well as effectively prevent filamentation of C. albicans cells (by 80%). Moreover, it was verified that anti-EFG1 2′OMe keeps the efficacy in different simulated human body fluids. Undeniably, this work provides potentially valuable information for future research into the management of Candida infections, regarding the development of a credible and alternative method to control C. albicans infections, based on AST methodology.