For the prevention of infectious diseases, knowledge about transmission routes is essential. In addition to respiratory, fecal–oral, and sexual transmission, the transfer of pathogens via surfaces plays a vital role for human pathogenic infections—especially nosocomial pathogens. Therefore, information about the survival of pathogens on surfaces can have direct implications on clinical measures, including hygiene guidelines and disinfection strategies. In this review, we reviewed the existing literature regarding viral, bacterial, and fungal persistence on inanimate surfaces. In particular, the current knowledge of the survival time and conditions of clinically relevant pathogens is summarized. While many pathogens persist only for hours, common nosocomial pathogens can survive for days to weeks under laboratory conditions and thereby potentially form a continuous source of transmission if no adequate inactivation procedures are performed.

Objectives: Interest in aspergillosis has increased over the past decades. An increase in the incidence of azole-resistant Aspergillus fumigatus strains has been reported; therefore, the need for novel therapeutic approaches is urgent. The formation of biofilms contributes to pathogen resistance. We investigated the biofilm formation capabilities of azole-resistant A. fumigatus and analysed the susceptibility of biofilms at various developmental stages to three antifungal agents. Methods: Biofilm formation of 19 clinical A. fumigatus strains (3 azole-susceptible and 16 azole-resistant strains) was determined by crystal violet staining and by an XTT assay over a period of 48 h. We measured antibiofilm activity of voriconazole, amphotericin B and olorofim. These agents were added before adhesion, after adhesion, after germination and to mature fungal biofilm. Antibiofilm activity was assessed in an XTT assay and in confocal laser scan microscopy. Additionally, a growth–kinetic assay with planktonic A. fumigatus was performed. Results: Each of the antifungal agents inhibited the metabolic activity of A. fumigatus biofilms when applied at early stages of biofilm formation. The mature biofilms were more resistant. Olorofim and voriconazole showed promising effects against A. fumigatus adhesion and germination, whereas the mature biofilm was not affected by treatment. In contrast, the biofilm of A. fumigatus showed amphotericin B susceptibility throughout the entire developmental process. The planktonic cells were susceptible to all three antifungal drug classes with an inhibition peak at 12 h after incubation. Conclusions: This is the first known study to demonstrate the antibiofilm activity of olorofim, voriconazole and amphotericin B against azole-resistant A. fumigatus.

The capability of Pseudomonas aeruginosa and Staphylococcus aureus to form biofilm on varying CI component materials differs in the presence and absence of bioactive glass (BAG). The application of BAG induces significant changes in biofilm morphology which can be visualized via scanning electron microscopy (SEM). Bacterial biofilm formation on medical devices, such as cochlear implants (CI), can lead to chronic infections. Interestingly, BAG of type S53P4 seems to be a promising tool for use in the reduction of biofilm development. Primarily, four bacterial species known to cause implant-related infections, P.aeruginosa (ATCC9027), S. aureus (ATCC6538), Staphylococcus epidermidis (ATCC12228) and Streptococcus pyogenes (ATCC19615) were analyzed regarding their capacity to form biofilm on CI components manufactured from three kinds of material: silicone, platinum and titanium. Subsequently, P. aeruginosa and S. aureus biofilms were visualized using scanning electron microscopy, comparing BAG-treated biofilm with non-treated biofilm. The four bacterial species presented biofilm-forming capabilities in a species and surface dependent manner. Metal CI components allowed for the greatest proliferation of biofilm. S. aureus and P. aeruginosa showed the highest rate of biofilm formation on polystyrene surfaces. For both species, SEM revealed altered biofilm morphology after treatment of S53P4 BAG. This study indicates that bacterial biofilm formation and structure on CI components is dependent on the surface composition, altering between metal and silicone surfaces. After application of BAG, changes in biofilm morphology on CI components were observed. These data highlight the impact of BAG on bacterial biofilm morphology.

This is the first study comparing three commercially available PCR assays for the detection of Aspergillus DNA from respiratory specimen of immunocompromised patients and the presence of cyp51A gene mutations. Bronchoalveolar lavages (BALs, N = 103) from patients with haematological/oncological underlying diseases were retrospectively investigated. The performance of three PCR assays, namely MycoGENIE^®Aspergillus fumigatus Real-Time PCR Kit (Adamtech), Fungiplex^®Aspergillus Azole-R IVD Real-Time PCR Kit (Bruker Daltonik GmbH) and AsperGenius^® (PathoNostics B.V.), were evaluated. All patients were categorised following current EORTC/MSG criteria, with exclusion of the PCR-results. From the 11 invasive pulmonary aspergillosis (IPA) probable samples, eight were detected with MycoGENIE^®, resulting in a sensitivity of 80% and a specificity of 73%. Furthermore, Fungiplex^® resulted in six positive BALs with a sensitivity of 60% and a specificity of 91% and AsperGenius^® in seven positive BAL samples, with a sensitivity of 64% and a specificity of 97%. No proven IPA was detected. One isolate showed phenotypically an azole-resistance, which was also detected in each of the tested PCR assays with the mutation in TR34. The here tested PCR assays were capable of reliably detecting A. fumigatus DNA, as well as differentiation of the common cyp51A gene mutations. However, evaluation on the AsperGenius^® assay revealed a low risk of false positive results.

Objectives: Patients with immunodeficiency or cystic fibrosis frequently suffer from respiratory fungal infections. In particular, biofilm-associated fungi cause refractory infection manifestations, linked to increased resistance to anti-infective agents. One emerging filamentous fungus is Lomentospora prolificans. Here, the biofilm-formation capabilities of L. prolificans isolates were investigated and the susceptibility of biofilms to various antifungal agents was analysed. Methods: Biofilm formation of L. prolificans (n = 11) was estimated by crystal violet stain and antibiofilm activity was additionally determined via detection of metabolically active biofilm using an XTT assay. Amphotericin B, micafungin, voriconazole and olorofim were compared with regard to their antibiofilm effects when added prior to adhesion, after adhesion and on mature and preformed fungal biofilms. Imaging via confocal laser scanning microscopy was carried out to demonstrate the effect of drug treatment on the fungal biofilm. Results: Antibiofilm activities of the tested antifungal agents were shown to be most effective on adherent cells whilst mature biofilm was the most resistant. The most promising antibiofilm effects were detected with voriconazole and olorofim. Olorofim showed an average minimum biofilm eradication concentration (MBEC) of 0.06 mg/L, when added prior to and after adhesion. The MBECs of voriconazole were ≤4 mg/L. On mature biofilm the MBECs of olorofim and voriconazole were higher than the previously determined MICs against planktonic cultures. In contrast, amphotericin B and especially micafungin did not exhibit sufficient antibiofilm activity against L. prolificans. Conclusions: To our knowledge, this is the first study demonstrating the antibiofilm potential of olorofim against the human pathogenic fungus L. prolificans.

Research into the cooperative pathogenicity of microbes in cystic fibrosis (CF) lungs is crucial for an understanding of the pathophysiology of infections and the development of novel treatment strategies. This study investigated the impact of the common CF-associated bacterial pathogen Pseudomonas aeruginosa on the black yeast Exophiala dermatitidis. It evaluated the planktonic growth, biofilm formation, morphology, and virulence of the fungus in the presence or absence of P. aeruginosa. It also determined the role of P. aeruginosa quorum-sensing (QS) molecules within these interactions, e.g., by using sterile culture filtrate and QS-deficient mutants. P. aeruginosa is known to inhibit the planktonic growth of E. dermatitidis. We found that fungal biofilm formation increased in the presence of P. aeruginosa after 24 h but is decreased significantly after 48 h. This effect was reversed when, instead of QS wild-type strains, ΔlasR, and ΔrhlR mutants were added to E. dermatitidis biofilm formation. The number and length of hyphae were substantially reduced when E. dermatitidis was co-cultivated with P. aeruginosa, but not when it was co-cultivated with the mutants. Experiments testing the virulence of E. dermatitidis in the greater wax moth Galleria mellonella showed a synergetic effect on larval killing when E. dermatitidis was injected together with P. aeruginosa culture filtrate. Survival rates were decreased when biofilm culture filtrate was added but not when planktonic culture filtrate was added. In summary, P. aeruginosa affects the growth, morphology, biofilm formation, and virulence of E. dermatitidis. N-acyl-L-homoserine lactone (AHL) QS molecules regulated factors that have been shown to contribute to the inhibition of the ability of E. dermatitidis to form filaments and biofilm.