Yeast-like filamentous fungi: Molecular identification and in vitro susceptibility study.

Yeast-like filamentous fungi, collected in Italy from 1985 to 2018, were submitted to molecular identification and antifungal susceptibility testings. Clinical isolates were identified as Magnusiomyces capitatus (28), M. clavatus (18), and Geotrichum candidum (2). M. clavatus was prevalent among blood isolates (18/24), M. capitatus among isolates from other biological materials. The intrinsic echinocandin resistance was confirmed. Both species had low minimum inhibitory concentrations (MICs) of itraconazole, posaconazole, and voriconazole, while M. clavatus had lower MIC of flucytosine and higher MIC of isavuconazole than M. capitatus. The intrinsic resistance of these species to echinocandins could be the reason of the recent increase of M. clavatus bloodstream infections.

CAND-LO 2014-15 study: changing epidemiology of candidemia in Lombardy (Italy).

PURPOSE: The aim of this study was to monitor recent changes in the epidemiology of candidemia and in the antifungal susceptibility profiles of Candida isolates in one Italian region (Lombardy) in 2014-2015 in comparison with two other studies performed in the same area in 1997-1999 and in 2009. METHODS: A laboratory-based surveillance was conducted in 11 microbiology laboratories. Identification of Candida isolates from 868 episodes and antifungal susceptibility testing (YeastOne) was performed locally. RESULTS: A progressive increase in the rate of candidemia up to 1.27/1000 admissions and 1.59/10,000 patient days was documented. In all the three surveys, Candida albicans remains the most frequently isolated species, ranging from 52 to 59 % of the etiology of BSIs. The epidemiological shift to the more resistant C. glabrata, observed between 1997-1999 and 2009 surveys, was not confirmed by our more recent data. The pattern of etiology of BSIs occurred in 2014-2015 overlaps that of the 90s. Acquired antifungal resistance is a rare event. No isolate had an amphoterin B minimal inhibitory concentration (MIC, mg/L) value higher than the epidemiological cutoff. All the echinocandin MIC distributions are typical for wild-type organisms except for those of two C. glabrata isolates. Fluconazole resistance declined from 24.9 % in the 2009 survey to 5.4 % in the recent one. CONCLUSIONS: Data from regional surveys may highlight the influence of therapeutic practices on the epidemiology of Candida BSIs and may optimize empirical therapies.

Clostridium difficile PCR Ribotype 018, a Successful Epidemic Genotype.

Clostridium difficile infection (CDI) became a public health problem for the global spreading of the so-called hypervirulent PCR ribotypes (RTs) 027 and 078, associated with increases in the transmission and severity of the disease. However, especially in Europe, several RTs are prevalent, and the concept of hypervirulence is currently debated. We investigated the toxin and resistance profiles and the genetic relatedness of 312 C. difficile strains isolated in a large Italian teaching hospital during a 5-year period. We evaluated the role of CDI-related antibiotic consumption and infection control practices on the RT predominance in association with their molecular features and transmission capacity. Excluding secondary cases due to nosocomial transmission, RT018 was the predominant genotype (42.4%) followed by RT078 (13.6%), while RT027 accounted for 0.8% of the strains. RT078 was most frequently isolated from patients in intensive care units. Its prevalence significantly increased over time, but its transmission capacity was very low. In contrast, RT018 was highly transmissible and accounted for 95.7% of the secondary cases. Patients with the RT018 genotype were significantly older than those with RT078 and other RTs, indicating an association between epidemic RT and age. We provide here the first epidemiological evidence to consider RT018 as a successful epidemic genotype that deserves more attention in clinical practice.

Epidemic MRSA clone ST22-IV is more resistant to multiple host- and environment-related stresses compared with ST228-I.

BACKGROUND: ST22-IV is a successful hospital-associated MRSA clone. Due to its known ability to replace other MRSA clones in hospitals, it became a dominant clone in Europe and beyond. So far, there are no studies investigating the relationship between the epidemiological success of MRSA clones and their capacity to withstand commonly encountered stresses. METHODS: We investigated the fitness of ST22-IV in comparison with the replaced clone ST228-I, evaluating its resistance to oxidative stress, autolytic activity, growth at high osmolarity and in acid and alkaline environments and survival under desiccation and heat shock. We also compared their phenotypic characteristics and examined the impact of antibiotic consumption on epidemiological success. RESULTS: Here we demonstrate that the dominance of ST22-IV is linked neither to changes in antibiotic consumption nor to acquisition of additional resistances over time. Strong α-haemolysin activity, the production of ß-haemolysin and the presence of an active agr could partly explain the virulence of ST22-IV previously observed in a murine model of pneumonia. Most importantly, we show that ST22-IV compared with ST228-I, besides retaining susceptibility to most antibiotics over time, has a superior capacity to survive under all stress conditions tested, which bacteria commonly face during their life cycle. CONCLUSIONS: Our results support our hypothesis that ST22-IV has a fitness advantage over ST228-I. This fitness advantage could have allowed ST22-IV to displace ST228-I without acquiring additional resistances and could help explain its epidemic success in hospital settings and its spread in Europe and beyond.

New role for human α-defensin 5 in the fight against hypervirulent Clostridium difficile strains.

Clostridium difficile infection (CDI), one of the most common hospital-acquired infections, is increasing in incidence and severity with the emergence and diffusion of hypervirulent strains. CDI is precipitated by antibiotic treatment that destroys the equilibrium of the gut microbiota. Human α-defensin 5 (HD5), the most abundant enteric antimicrobial peptide, is a key regulator of gut microbiota homeostasis, yet it is still unknown if C. difficile, which successfully evades killing by other host microbicidal peptides, is susceptible to HD5. We evaluated, by means of viability assay, fluorescence-activated cell sorter (FACS) analysis, and electron microscopy, the antimicrobial activities of α-defensins 1 and 5 against a panel of C. difficile strains encompassing the most prevalent epidemic and hypervirulent PCR ribotypes in Europe (012, 014/020, 106, 018, 027, and 078). Here we show that (i) concentrations of HD5 within the intestinal physiological range produced massive C. difficile cell killing; (ii) HD5 bactericidal activity was mediated by membrane depolarization and bacterial fragmentation with a pattern of damage peculiar to C. difficile bacilli, compared to commensals like Escherichia coli and Enterococcus faecalis; and (iii) unexpectedly, hypervirulent ribotypes were among the most susceptible to both defensins. These results support the notion that HD5, naturally present at very high concentrations in the mucosa of the small intestine, could indeed control the very early steps of CDI by killing C. difficile bacilli at their germination site. As a consequence, HD5 can be regarded as a good candidate for the containment of hypervirulent C. difficile strains, and it could be exploited in the therapy of CDI and relapsing C. difficile-associated disease.

Factors contributing to epidemic MRSA clones replacement in a hospital setting.

The mechanisms governing the epidemiology dynamics and success determinants of a specific healthcare-associated methicillin-resistant S. aureus (HA-MRSA) clone in hospital settings are still unclear. Important epidemiological changes have occurred in Europe since 2000 that have been related to the appearance of the ST22-IV clone. Between 2006 and 2010, we observed the establishment of the ST22-IV clone displacing the predominant Italian clone, ST228-I, in a large Italian university hospital. To investigate the factors associated with a successful spread of epidemic MRSA clones we studied the biofilm production, the competitive behavior in co-culture, the capacity of invasion of the A549 cells, and the susceptibility to infection in a murine model of acute pneumonia of the two major HA-MRSA clones, ST22-IV and ST228-I. We showed that persistence of ST22-IV is associated with its increased biofilm production and capacity to inhibit the growth of ST228-I in co-culture. Compared to ST228-I, ST22-IV had a significantly higher capacity to invade the A549 cells and a higher virulence in a murine model of acute lung infection causing severe inflammation and determining death in all the mice within 60 hours. On the contrary, ST228-I was associated with mice survival and clearance of the infection. ST22-IV, compared with ST228-I, caused a higher number of persistent, long lasting bacteremia. These data suggest that ST22-IV could have exploited its capacity to i) increase its biofilm production over time, ii) maintain its growth kinetics in the presence of a competitor and iii) be particularly invasive and virulent both in vitro and in vivo, to replace other well-established MRSA clones, becoming the predominant European clone.

Invasive fungal infections in the intensive care unit: a multicentre, prospective, observational study in Italy (2006-2008).

Critically ill patients admitted to intensive care units (ICU) are highly susceptible to healthcare-associated infections caused by fungi. A prospective sequential survey of invasive fungal infections was conducted from May 2006 to April 2008 in 38 ICUs of 27 Italian hospitals. A total of 384 fungal infections (318 invasive Candida infections, three cryptococcosis and 63 mould infections) were notified. The median rate of candidaemia was 10.08 per 1000 admissions. In 15% of cases, the infection was already present at the time of admission to ICU. Seventy-seven percent of Candida infections were diagnosed in surgical patients. Candida albicans was isolated in 60% of cases, Candida glabrata and Candida parapsilosis in 13%, each. Candida glabrata had the highest crude mortality rate (60%). Aspergillus infection was diagnosed in 32 medical and 25 surgical patients. The median rate was 6.31 per 1000 admissions. Corticosteroid treatment was the major host factor. Aspergillosis was demonstrated to be more severe than candidiasis as the crude mortality rate was significantly higher (63% vs. 46%), given an equal index of severity, Simplified Acute Physiology Score (SAPS-II). The present large nationwide survey points out the considerable morbidity and mortality of invasive fungal infections in surgical as well as medical patients in ICU.

Cross-reactivity of Fusarium spp. in the Aspergillus Galactomannan enzyme-linked immunosorbent assay.

Nine of 11 hematological patients with disseminated/deep-seated Fusarium infection tested at least twice for Aspergillus galactomannan (GM) had repeated positive results in the absence of Aspergillus isolation in culture. The centrifuged supernatants of 12 Fusarium isolates were tested by a GM enzyme-linked immunosorbent assay (EIA). All the isolates produced positive reactions when tested undiluted. These results show cross-reactivity of Fusarium spp. with Aspergillus GM that may constitute a drawback with respect to the specificity of the Platelia EIA.

Fatal vancomycin- and linezolid-resistant Enterococcus faecium sepsis in a child undergoing allogeneic haematopoietic stem cell transplantation for beta-thalassaemia major.

Recently vancomycin-resistant and sporadically linezolid-resistant Enterococcus species have been described in adults. We report what we believe to be the first case of a child with prolonged bone marrow aplasia following haematopoietic stem cell transplantation developing a fatal sepsis caused by Enterococcus faecium resistant to glycopeptides and linezolid.

Species distribution and in vitro antifungal susceptibility patterns of 75 clinical isolates of Fusarium spp. from northern Italy.

Fusarium isolates from 75 Italian patients were identified by molecular methods, and their susceptibilities to antifungals were tested in vitro. Fusarium verticillioides was the species most frequently isolated from deep-seated infections, and F. solani was the species most frequently isolated from superficial infections. F. solani isolates showed high azole MICs, while F. verticillioides isolates showed low posaconazole MICs.

Development and validation of a molecular method for the diagnosis of medically important fungal infections.

The increasing incidence of severe fungal infections highlights the need for rapid and precise identification methods in clinical mycology. The aim of this study was to develop and validate a culture-indipendent molecular approach that could allow the detection of fungal pathogens in clinical samples, with particular attention to the identification of drug-resistant Candida and Aspergillus species. A real-time multiplex PCR assay was developed using TaqMan probes specific for highly discriminating ITS sequences. In its multiplex format the assay showed a high specificity, clearly discriminating among different species, as well as a high sensitivity (20 CFU/1 mL sample), making it a potentially useful starting point for the development of a more complete molecular diagnostic assay.

Rapid molecular identification of fungal pathogens in corneal samples from suspected keratomycosis cases.

An increase in the incidence of fungal infections has highlighted the need for rapid and precise detection and identification methods in clinical mycology. This report describes the data obtained on corneal samples from 24 patients with suspected keratomycosis using a conventional cultural approach in parallel with PCR amplification and sequencing of the internal transcribed spacers (ITSs) of the rDNA regions. Using the cultural approach, seven samples (58.3 % of the 12 samples positive for an infectious pathogen) tested positive for a fungal aetiology, with final identification taking a mean time of more than 5 days. In two cases, diagnosis required 10 days. Using the ITS-based molecular approach, a direct diagnosis was obtained in only five of the seven fungus-positive cases (71.4 %) starting from the clinical samples, but identification was still possible in all seven cases within 24 h (by using 16 h cultures for the two remaining cases). Despite the less-than-optimal sensitivity when working directly on clinical samples, the obtained data indicate that the molecular strategy used in this study is a useful complement to the conventional diagnostic approaches used for keratomycosis and, in particular, allows precise and fast fungal identification, in response to the clinical requirements. Similar studies on larger panels of patients and on different clinical samples are required for further investigation of the clinical potential of ITS-based approaches in the diagnosis of mycotic infections.

Direct sequencing of Scedosporium apiospermum DNA in the diagnosis of a case of keratitis.

The present report describes the diagnostic strategy followed in a case of keratomycosis. Together with conventional methods, a molecular strategy that involved the direct sequencing of an amplified portion of the genome encompassing the internal transcribed spacer 1 and 2 regions and sequence analysis was used. The data highlight the diagnostic role of molecular techniques, in parallel with conventional methods, in the management of ocular infections of fungal aetiology.

Legionella infection risk from domestic hot water.

We investigated Legionella and Pseudomonas contamination of hot water in a cross-sectional multicentric survey in Italy. Chemical parameters (hardness, free chlorine, and trace elements) were determined. Legionella spp. were detected in 33 (22.6%) and Pseudomonas spp. in 56 (38.4%) of 146 samples. Some factors associated with Legionella contamination were heater type, tank distance and capacity, water plant age, and mineral content. Pseudomonas presence was influenced by water source, hardness, free chlorine, and temperature. Legionella contamination was associated with a centralized heater, distance from the heater point >10 m, and a water plant >10 years old. Furthermore, zinc levels of <100 microg/L and copper levels of >50 microg/L appeared to be protective against Legionella colonization [corrected]. Legionella species and serogroups were differently distributed according to heater type, water temperature, and free chlorine, suggesting that Legionella strains may have a different sensibility and resistance to environmental factors and different ecologic niches.