Unveiling the mechanism of action of acylated temporin L analogues against multidrug-resistant Candida albicans.

The increasing resistance of fungi to conventional antifungal drugs has prompted worldwide the search for new compounds. In this work, we investigated the antifungal properties of acylated Temporin L derivatives, Pent-1B and Dec-1B, against Candida albicans, including the multidrug-resistant strains. Acylated peptides resulted to be active both on reference and clinical strains with MIC values ranging from 6.5 to 26 µM, and they did not show cytotoxicity on human keratinocytes. In addition, we also observed a synergistic or additive effect with voriconazole for peptides Dec-1B and Pent-1B through the checkerboard assay on voriconazole-resistant Candida strains. Moreover, fluorescence-based assays, NMR spectroscopy, and confocal microscopy elucidated a potential membrane-active mechanism, consisting of an initial electrostatic interaction of acylated peptides with fungal membrane, followed by aggregation and insertion into the lipid bilayer and causing membrane perturbation probably through a carpeting effect.

Antibiotic and Nematocidal Metabolites from Two Lichen Species Collected on the Island of Lampedusa (Sicily).

The antibiotic and nematocidal activities of extracts from two coastal lichen species collected on Lampedusa Island (Sicily), Ramalina implexa Nyl. and Roccella phycopsis Ach., were tested. Methyl orsellinate, orcinol, (+)-montagnetol, and for the first time 4-chlororcinol were isolated from Roccella phycopsis. (+)-Usnic acid was obtained from Ramalina implexa. The crude organic extract of both lichen species showed strong antibiotic activity against some bacterial species and nematocidal activity. Among all the pure metabolites tested against the infective juveniles (J2) of the root-knot nematode (RKN) Meloydogine incognita, (+)-usnic acid, orcinol, and (+)-montagnetol had significant nematocidal activity, comparable with that of the commercial nematocide Velum® Prime, and thus they showed potential application in agriculture as a biopesticide. On the contrary, methyl orsellinate and 4-chlororcinol had no nematocidal effect. These results suggest that the substituent pattern at ortho-para-position in respect to both hydroxyl groups of resorcine moiety, which is present in all metabolites, seems very important for nematocidal activity. The organic extracts of both lichens were also tested against some Gram-positive and Gram-negative bacteria. Both extracts were active against Gram-positive species. The extract of Ramalina implexa showed, among Gram-negative species, activity against Escherichia coli and Acinetobacter baumannii, while that from Roccella phycopsis was effective towards all test strains, with the exception of Pseudomonas aeruginosa. The antimicrobial activity of (+)-usnic acid, methyl orsellinate, and (+)-montagnetol is already known, so tests were focused on orcinol and 4-chlororcinol. The former showed antibacterial activity against all Gram positive and Gram-negative test strains, with the exception of A. baumannii and K. pneumoniae, while the latter exhibited a potent antibacterial activity against Gram-positive test strains and among Gram-negative strains, was effective against A. baumannii and K. pneumonia. These results suggest, for orcinol and 4-chlororcinol, an interesting antibiotic potential against both Gram-positive and Gram-negative bacterial strains.

Do isolates from pharyngeal and rectal swabs match blood culture bacterial pathogens in septic VLBW infants? A pilot, cross-sectional study.

Serial body site swabbing is used to monitor horizontal spread of aggressive bacterial species in the neonatal intensive care unit (NICU). Since colonization/carriage is thought to precede systemic infection, one might expect to retrieve colonizing pathogens from blood cultures. This hypothesis, however, has not been fully investigated in very low birth weight (VLBW) infants that are at high sepsis' risk. The primary outcome was, in a population of VLBW infants with late-onset sepsis, the matching between blood culture results and pathogens isolated from rectal and nose/pharyngeal surveillance swabs in the preceding 2 weeks. The secondary outcomes were the site of swabbing and time interval from colonization to blood culture positivity. Out of 333 VLBW neonates, 80 (24%) were diagnosed with bacterial sepsis. In 46 (57%) neonates, the blood culture showed the same pathogen species cultured from a swab. Of these, 30 were isolated from infants with both body sites colonized with an average time interval of 3.5 days; 2/16 were isolated from rectal swabs and 14 /16 from nose/pharyngeal samples.Conclusion: Our data show a fair correspondence between bacteria colonizing the nasopharynx and/or the rectum and pathogens later isolated from blood cultures. This association depends on the swabbing site, number of sites, and pathogen species. Although these data constitute valuable results, they are not sufficient for providing the sole base of a thoughtful clinical decision. What is Known: • Body site's colonization may precede systemic infection. • Little is known on this mechanism in VLBW infants that are at higher sepsis' risk. What is New: •Colonizing bacteria partially correspond to pathogens of blood cultures in VLBW infants with sepsis. • Correspondence depends on swabbing site, number of sites, and pathogen species.

Novel temporin L antimicrobial peptides: promoting self-assembling by lipidic tags to tackle superbugs.

The rapid development of antimicrobial resistance is pushing the search in the discovering of novel antimicrobial molecules to prevent and treat bacterial infections. Self-assembling antimicrobial peptides, as the lipidated peptides, are a novel and promising class of molecules capable of meeting this need. Based on previous work on Temporin L analogs, several new molecules lipidated at the N- or and the C-terminus were synthesised. Our goal is to improve membrane interactions through finely tuning self-assembly to reduce oligomerisation in aqueous solution and enhance self-assembly in bacterial membranes while reducing toxicity against human cells. The results here reported show that the length of the aliphatic moiety is a key factor to control target cell specificity and the oligomeric state of peptides either in aqueous solution or in a membrane-mimicking environment. The results of this study pave the way for the design of novel molecules with enhanced activities.

Bacterial biofilm formation is variably inhibited by different formulations of antibiotic-loaded bone cement in vitro.

PURPOSE: The aim of the present study was to quantitatively assess biofilm growth on the surface of bone cements discs containing different antibiotics, including colistin and linezolid. Biofilms of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Staphylococcus epidermidis were grown on bone cement discs for 96 h. METHODS: Biofilm amounts were measured by confocal laser microscopy using live/dead staining and dedicated software at different time intervals (48, 72, and 96 h). RESULTS: Bone cement containing vancomycin was not effective at reducing MRSA biofilm formation 96 h following bacterial inoculation. At a comparable time interval, linezolid-, clindamycin-, and aminoglycoside-loaded cement was still active against this biofilm. At the 72- and 96-h observations, S. epidermidis biofilm was present only on tobramycin and gentamicin discs. P. aeruginosa biofilms were present on cement discs loaded with colistin at all time intervals starting from the 48-h observation, whereas no biofilms were detected on tobramycin or gentamicin discs. CONCLUSION: Bone cements containing different antibiotics have variable and time-dependent windows of activity in inhibiting or reducing surface biofilm formation. The effectiveness of bone cement containing vancomycin against MRSA biofilm is questionable. The present study is clinically relevant, because it suggests that adding the right antibiotic to bone cement could be a promising approach to treat periprosthetic infections. Indeed, the antibiofilm activity of different antibiotic-loaded bone cements could be preoperatively assessed using the current methodology in two-stage exchange procedures.

A rare case of infant sepsis due to the emm-89 genotype of Group A Streptococcus within a community-acquired cluster.

Invasive Group A Streptococcus disease is a severe and sometimes life-threatening infection with only few cases reported in literature. We describe the case of a 49-day-old male infant with invasive Group A Streptococcus infection characterized by acute otitis media and development of septicemia within a probably community-acquired cluster. The causative agent resulted to be a rare emm-89 genotype of Streptococcus pyogenes. Group A Streptococcus must be considered responsible for sepsis in newborns and young infants.

Development of a real-time PCR assay for the rapid detection of Acinetobacter baumannii from whole blood samples.

Acinetobacter baumannii is a multidrug-resistant pathogen associated with severe infections in hospitalized patients, including pneumonia, urinary and bloodstream infections. Rapid detection of A. baumannii infection is crucial for timely treatment of septicemic patients. The aim of the present study was to develop a specific marker for a quantitative polymerase chain reaction (PCR) assay for the detection of A. baumannii. The target gene chosen is the biofilm-associated protein (bap) gene, encoding a cell surface protein involved in biofilm formation. The assay is specific for A. baumannii, allowing its discrimination from different species of Acinetobacter and other clinically relevant bacterial pathogens. The assay is able to detect one genomic copy of A. baumannii, corresponding to 4 fg of purified DNA, and 20 colony-forming units/ml using DNA extracted from spiked whole blood samples.

Mitochondrial Malfunctioning, Proteasome Arrest and Apoptosis in Cancer Cells by Focused Intracellular Generation of Oxygen Radicals.

Photofrin/photodynamic therapy (PDT) at sub-lethal doses induced a transient stall in proteasome activity in surviving A549 (p53(+/+)) and H1299 (p53(-/-)) cells as indicated by the time-dependent decline/recovery of chymotrypsin-like activity. Indeed, within 3 h of incubation, Photofrin invaded the cytoplasm and localized preferentially within the mitochondria. Its light activation determined a decrease in mitochondrial membrane potential and a reversible arrest in proteasomal activity. A similar result is obtained by treating cells with Antimycin and Rotenone, indicating, as a common denominator of this effect, the ATP decrease. Both inhibitors, however, were more toxic to cells as the recovery of proteasomal activity was incomplete. We evaluated whether combining PDT (which is a treatment for killing tumor cells, per se, and inducing proteasome arrest in the surviving ones) with Bortezomib doses capable of sustaining the stall would protract the arrest with sufficient time to induce apoptosis in remaining cells. The evaluation of the mitochondrial membrane depolarization, residual proteasome and mitochondrial enzymatic activities, colony-forming capabilities, and changes in protein expression profiles in A549 and H1299 cells under a combined therapeutic regimen gave results consistent with our hypothesis.

Photodynamic and Antibiotic Therapy in Combination to Fight Biofilms and Resistant Surface Bacterial Infections.

Although photodynamic therapy (PDT), a therapeutic approach that involves a photosensitizer, light and O2, has been principally considered for the treatment of specific types of cancers, other applications exist, including the treatment of infections. Unfortunately, PDT does not always guarantee full success since it exerts lethal effects only in cells that have taken up a sufficient amount of photosensitizer and have been exposed to adequate light doses, conditions that are not always achieved. Based on our previous experience on the combination PDT/chemotherapy, we have explored the possibility of fighting bacteria that commonly crowd infected surfaces by combining PDT with an antibiotic, which normally does not harm the strain at low concentrations. To this purpose, we employed 5-aminolevulinic acid (5-ALA), a pro-drug that, once absorbed by proliferating bacteria, is converted into the natural photosensitizer Protoporphyrin IX (PpIX), followed by Gentamicin. Photoactivation generates reactive oxygen species (ROS) which damage or kill the cell, while Gentamicin, even at low doses, ends the work. Our experiments, in combination, have been highly successful against biofilms produced by several Gram positive bacteria (i.e., Staphylococcus aureus, Staphylococcus epidermidis, etc.). This original approach points to potentially new and wide applications in the therapy of infections of superficial wounds and sores.

Typing of Ochrobactrum anthropi clinical isolates using automated repetitive extragenic palindromic-polymerase chain reaction DNA fingerprinting and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry.

BACKGROUND: Ochrobactrum anthropi (O. anthropi), is a non-fermenting gram-negative bacillus usually found in the environment. Nevertheless, during the past decade it has been identified as pathogenic to immunocompromised patients. In this study, we assessed the usefulness of the automated repetitive extragenic palindromic-polymerase chain reaction (rep-PCR-based DiversiLab™ system, bioMèrieux, France) and of matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF MS) for typing of twentythree O. anthropi clinical isolates that we found over a four-months period (from April 2011 to August 2011) in bacteriemic patients admitted in the same operative unit of our hospital. Pulsed-field gel electrophoresis (PFGE), commonly accepted as the gold standard technique for typing, was also used. Analysis was carried out using the Pearson correlation coefficient to determine the distance matrice and the unweighted pair group method with arithmetic mean (UPGMA) to generate dendogram. RESULTS: Rep-PCR analysis identified four different patterns: three that clustered together with 97% or more pattern similarity, and one whose members showed < 95% pattern similarity. Interestingly, strains isolated later (from 11/06/2011 to 24/08/2011) displayed a pattern with 99% similarity. MALDI-TOF MS evaluation clustered the twentythree strains of O. anthropi into a single group containing four distinct subgroups, each comprising the majority of strains clustering below 5 distance levels, indicating a high similarity between the isolates. CONCLUSIONS: Our results indicate that these isolates are clonally-related and the methods used afforded a valuable contribution to the epidemiology, prevention and control of the infections caused by this pathogen.

Identification of Inquilinus limosus in cystic fibrosis: a first report in Italy.

Cystic fibrosis is a genetic disorder associated with a polymicrobial lung infection where classical pathogens and newly identified bacteria may interact. Inquilinus limosus is an a-proteobacterium recently isolated in the airways of cystic fibrosis patient. We report the first case in Italy of I.limosus isolation from the sputum sample of a cystic fibrosis patient. The patient is a 20-years-old man with cystic fibrosis, regularly attending the Regional Care Center for Cystic Fibrosis at the Federico II University Hospital of Naples. Microbiological culture methods detected a mu- coid gram negative bacillus in the patient's sputum sample. The isolate exhibited a distinct antimicrobial suscep- tibility profile with a high MIC for several drugs. The MALDI-TOF mass spectrometry analysis indicated the bac- terium isolated as I. limosus, confirmed by 16s rDNA sequence analysis. The described clinical case demonstrates how the bacterial biodiversity in the airways of cystic fibrosis patients is still underestimated. Cystic fibrosis lung represents an ecological niche suitable for growth of a wide variety of unusual bacteria not commonly associated with human diseases, such as I. limosus. Therefore further studies are needed to evaluate the epidemiology and clinical implications of I. limosus in the physiopathology of cystic fibrosis lung infection.

Antibacterial Metabolites Produced by Limonium lopadusanum, an Endemic Plant of Lampedusa Island.

Lampedusa, the largest island of the Pelagie archipelago, Sicily, Italy, has proven to be a rich source of plants and shrubs used in folk medicine. These plants, often native to the island, have been very poorly investigated for their phytochemical composition and biological potential to be translated into pharmacological applications. To start achieving this purpose, a specimen of Limonium lopadusanum, a plant native to Lampedusa, was investigated for the first time. This manuscript reports the results of a preliminary biological assay, focused on antimicrobial activity, carried out using the plant organic extracts, and the isolation and chemical and biological characterization of the secondary metabolites obtained. Thus 3-hydroxy-4-methoxybenzoic acid methyl ester (syn: methyl isovanillate, (1), methyl syringate (2), pinoresinol (3), erythrinassinate C (4) and tyrosol palmitate (5) were isolated. Their antimicrobial activity was tested on several strains and compound 4 showed promising antibacterial activity against Enterococcus faecalis. Thus, this metabolite has antibiotic potential against the drug-resistant opportunistic pathogen E. faecalis.

Corrigendum: Endometrial microbiota profile in in-vitro fertilization (IVF) patients by culturomics-based analysis.

[This corrects the article DOI: 10.3389/fendo.2023.1204729.].

Antiseptics' Concentration, Combination, and Exposure Time on Bacterial and Fungal Biofilm Eradication.

Background: This study aims to assess the activity of solutions containing povidone-iodine (PI) and hydrogen peroxide (H2O2) alone or combined on the biofilm of microbial species in the contest of periprosthetic joint infection (PJI). Methods: Different antiseptic solutions were tested on 2-day-old biofilms of Gram-positive and Gram-negative bacteria and fungi at 1 and 3 minutes of exposure. The efficacy of these solutions was evaluated by measuring the biofilm metabolic activity by methoxynitrosulfophenyl-tetrazolium carboxanilide (XTT) reduction assay. The anti-biofilm effect of 5% PI and 0.3% PI + 0.5% H2O2 was tested on a 5-day-old biofilm using colony-forming unit counts and an XTT reduction assay. Results: PI and H2O2 solutions showed concentration-dependent anti-biofilm activity except for E. faecalis. PI at 5% was the most active solution against the 2-day-old biofilm of all test microorganisms. The 0.3% PI + 0.5% H2O2 solution had a significant effect only at 3 minutes. The 5% PI and 0.3% PI + 0.5% H2O2 effect was evaluated on 5-day-old biofilms. PI at 5% produced a significant reduction in metabolic activity at both 1 and 3 minutes; 0.3% PI + 0.5% H2O2 caused a significant activity against all Gram-positive strains after 3 minutes, with a greater metabolic activity reduction than 5% PI. Conclusions: In the case of PJI caused by Gram-positive bacteria, 0.3% PI + 0.5% H2O2 could be used for wound irrigation for 3 minutes of exposure. In the case of PJI with a different etiological agent or PJI with an unknown etiology, it is advisable to use 5% PI for 1 minute of exposure.

Endometrial microbiota profile in in-vitro fertilization (IVF) patients by culturomics-based analysis.

Introduction: It is well recognized that the human uterus and adjoining tissues of the female reproductive tract exist in a non-sterile state where dysbiosis can impact reproductive outcomes. The endometrial microbiota is a part of this greater milieu. To date, it has largely been studied using 16S rRNA or metagenomics-based methodologies. Despite the known advantages of sequencing analysis, several difficulties have been noted including sample contamination and standardization of DNA extraction or sequencing. The aim of this study was to use a culturomics-based method to analyze the endometrial microbiota and correlate the results with ongoing pregnancy rates. Methods: A prospective cohort study was performed at the University of Naples from June 2022 to December 2022. Ninety-three patients undergoing an IVF cycle with single embryo transfer (ET) (fresh or frozen) were enrolled in the study. Following ET, the catheter tip was inserted into brain heart infusion (BHI) medium under sterile conditions for culture. After 24h and 48h of incubation the microorganisms in the colonies were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Results: Overall, 68 (73,92%) patients resulted positive for one or more microbes and 25 patients (26,08%) had no microbial growth. Across all participants, the four most important phyla were Firmicutes (87,76%), Proteobacteria (27,94%), Actinobacteria (10,29%) and Ascomycota (8,82%). Lactobacillus species, in particular, was significantly correlated with ongoing pregnancy rate (p=0,05). On the other hand, Staphylococcus subspecies (spp.) (p<0,05) and Enterobacteriaceae (p<0,001) were found to have a negative impact on the implantation rate. Discussion: Detection of bacteria by culturomics from catheter tips used for embryo transfer has been shown to be a reliable method to detect pathogen growth. Endometrial microbiota testing in clinical practice could certainly offer a means to further improve diagnosis and treatment strategies in IVF patients.

Invasive Fungal Infections in Hospitalized Patients with COVID-19: A Non-Intensive Care Single-Centre Experience during the First Pandemic Waves.

Invasive fungal infections (IFIs) represent a severe complication of COVID-19, yet they are under-estimated. We conducted a retrospective analysis including all the COVID-19 patients admitted to the Infectious Diseases Unit of the Federico II University Hospital of Naples until the 1 July 2021. Among 409 patients, we reported seven cases of IFIs by Candida spp., seven of Pneumocystis jirovecii pneumonia, three of invasive pulmonary aspergillosis, and one of Trichosporon asahii. None of the cases presented underlying predisposing conditions, excluding one oncohematological patient treated with rituximab. Ten cases showed lymphopenia with high rates of CD4+ < 200/µL. All cases received high-dose steroid therapy (mean duration 33 days, mean cumulative dosage 1015 mg of prednisone equivalent), and seven cases had severe COVID-19 disease (OSCI ≥ 5) prior to IFI diagnosis. The cases showed a higher overall duration of hospitalization (63 vs 24 days) and higher mortality rate (23% vs. 7%) compared with the COVID-19 patients who did not developed IFIs. Cases showed a higher prevalence of high-dose steroid therapy and lymphopenia with CD4+ < 200/µL, primarily due to SARS-CoV-2 infection and not related to underlying comorbidities. IFIs strongly impact the overall length of hospitalization and mortality. Therefore, clinicians should maintain a high degree of suspicion of IFIs, especially in severe COVID-19 patients.

Repurposing Selamectin as an Antimicrobial Drug against Hospital-Acquired Staphylococcus aureus Infections.

The emergence of multidrug-resistant strains requires the urgent discovery of new antibacterial drugs. In this context, an antibacterial screening of a subset of anthelmintic avermectins against gram-positive and gram-negative strains was performed. Selamectin completely inhibited bacterial growth at 6.3 µg/mL concentrations against reference gram-positive strains, while no antibacterial activity was found against gram-negative strains up to the highest concentration tested of 50 µg/mL. Given its relevance as a community and hospital pathogen, further studies have been performed on selamectin activity against Staphylococcus aureus (S. aureus), using clinical isolates with different antibiotic resistance profiles and a reference biofilm-producing strain. Antibacterial studies have been extensive on clinical S. aureus isolates with different antibiotic resistance profiles. Mean MIC90 values of 6.2 µg/mL were reported for all tested S. aureus strains, except for the macrolide-resistant isolate with constitutive macrolide-lincosamide-streptogramin B resistance phenotype (MIC90 9.9 µg/mL). Scanning Electron Microscopy (SEM) showed that selamectin exposure caused relevant cell surface alterations. A synergistic effect was observed between ampicillin and selamectin, dictated by an FIC value of 0.5 against methicillin-resistant strain. Drug administration at MIC concentration reduced the intracellular bacterial load by 81.3%. The effect on preformed biofilm was investigated via crystal violet and confocal laser scanning microscopy. Selamectin reduced the biofilm biomass in a dose-dependent manner with minimal biofilm eradication concentrations inducing a 50% eradication (MBEC50) at 5.89 µg/mL. The cytotoxic tests indicated that selamectin exhibited no relevant hemolytic and cytotoxic activity at active concentrations. These data suggest that selamectin may represent a timely and promising macrocyclic lactone for the treatment of S. aureus infections.

Multicenter study on the prevalence of colonization due to carbapenem-resistant Enterobacterales strains before and during the first year of COVID-19, Italy 2018-2020.

Background: Among multidrug-resistant (MDR) bacteria able to threaten human health, carbapenem-resistant Enterobacterales (CRE) have become a major public health threat globally. National and international guidelines point out the importance of active routine surveillance policies to prevent CRE transmission. Therefore, defining lines of intervention and strategies capable of containing and controlling the spread of CRE is considered determinant. CRE screening is one of the main actions to curb transmission and control outbreaks, outlining the presence and also the prevalence and types of carbapenemase enzymes circulating locally. Objective: The purpose of this study was to outline the epidemiology of CRE colonization in Italy, detecting CRE-colonized patients at admission and during hospitalization, before and during the first year of COVID-19. Materials and methods: A total of 11,063 patients admitted to seven different hospitals (Bologna, Catania, Florence, Genoa, Naples, Palermo, and Turin) in Intensive Care Units (ICU) and other wards (non-ICU) located in the North, Center, and South of Italy were enrolled and screened for CRE carriage at admission (T0) and during the first 3 weeks of hospitalization (T1-T3). The study spanned two periods, before (September 2018-Septemeber 2019, I observational period) and during the COVID-19 pandemic (October 2019-September 2020, II observational period). Results: Overall, the prevalence of CRE-colonized patients at admission in ICU or in other ward, ranged from 3.9 to 11.5%, while a percentage from 5.1 to 15.5% of patients acquired CRE during hospital stay. There were large differences between the I and II period of study according to the different geographical areas and enrolling centers. Overall, comparison of prevalence of CRE-positive patients showed a significant increased trend between I and II observational periods both in ICU and non-ICU wards, mostly in the Southern participating centers. KPC-producing Klebsiella pneumoniae was the most frequent CRE species-carbapenemase combination reported in this study. In particular, the presence of KPC-producing K. pneumoniae was reported in period I during hospitalization in all the CRE-positive patients enrolled in ICU in Turin (North Italy), while in period II at admission in all the CRE-positive patients enrolled in ICU in Catania and in 58.3% of non-ICU CRE-positive patients in Naples (both centers in South Italy). Conclusion: The prevalence of CRE in Italy highly increased during the COVID-19 pandemic, mostly in the Southern hospital centers. KPC-producing K. pneumoniae was the most frequent colonizing CRE species reported. The results of our study confirmed the crucial value of active surveillance as well as the importance of multicenter studies representing diverse geographical areas even in endemic countries. Differences in CRE colonization prevalence among centers suggest the need for diversified and center-specific interventions as well as for strengthening efforts in infection prevention and control practices and policies.

Ambroxol influences voriconazole resistance of Candida parapsilosis biofilm.

The ability to form biofilm on different surfaces is typical of most Candida species. Microscopic structure and genetic aspects of fungal biofilms have been the object of many studies because of very high resistance to antimycotic agents because of the scarce permeability of the external matrix and to the alterations in cell metabolism. In our study, 31 isolates of Candida parapsilosis, isolated from bloodstream infections, were tested for their ability to produce biofilm and were found to be good producers. The susceptibility to voriconazole, assayed by colorimetrical XTT assay, revealed a very elevated minimum inhibitory concentrations for sessile cells in comparison with planktonic ones. The addition of ambroxol, a mucolytic agent, increased the susceptibility of biofilm forming cells to voriconazole. Expression of the efflux pump genes CDR and MDR was analyzed in biofilms alone or treated with ambroxol, evidencing a role of ambroxol in the expression of genes involved in azole resistance mechanisms of C. parapsilosis biofilms. In conclusion, our data seem to encourage the use of different substances in combination with classical antimycotics, with the aim of finding a solution to the increasing problem of the resistance of biofilms formed on medical devices by nonalbicans Candida species.