Anti-Biofilm Effect of Hybrid Nanocomposite Functionalized with Erythrosine B on Staphylococcus aureus Due to Photodynamic Inactivation.

Resistant biofilms formed by Staphylococcus aureus on medical devices pose a constant medical threat. A promising alternative to tackle this problem is photodynamic inactivation (PDI). This study focuses on a polyurethane (PU) material with an antimicrobial surface consisting of a composite based on silicate, polycation, and erythrosine B (EryB). The composite was characterized using X-ray diffraction and spectroscopy methods. Anti-biofilm effectiveness was determined after PDI by calculation of CFU mL-1. The liquid PU precursors penetrated a thin silicate film resulting in effective binding of the PU/silicate composite and the PU bulk phases. The incorporation of EryB into the composite matrix did not significantly alter the spectral properties or photoactivity of the dye. A green LED lamp and laser were used for PDI, while irradiation was performed for different periods. Preliminary experiments with EryB solutions on planktonic cells and biofilms optimized the conditions for PDI on the nanocomposite materials. Significant eradication of S. aureus biofilm on the composite surface was achieved by irradiation with an LED lamp and laser for 1.5 h and 10 min, respectively, resulting in a 10,000-fold reduction in biofilm growth. These results demonstrate potential for the development of antimicrobial polymer surfaces for modification of medical materials and devices.

Synthesis and structure-activity relationship of berkeleylactone A-derived antibiotics.

Berkeleylactone A is a potent 16-membered macrolactone antibiotic, recently isolated from a coculture of Berkeley Pit Lake fungi. Although its antimicrobial activity has already been investigated, little is known about the structure-activity relationship. Based on our previous synthetic studies, a series of berkeleylactone A derivatives were synthesized and evaluated for their in vitro antimicrobial activities against methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MRSA) strains. Our data confirmed the essential role of the embedded conjugated system and suggest a reversible sulfa-protection of the Michael acceptor as a viable option. Structurally simplified achiral macrolactam 8 showed the best inhibitory activity against S. aureus L12 (MRSA) with MIC50 values of 0.39 µg mL-1, 8-fold lower than those of berkeleylactone A. These studies may be of value in the development of more advanced candidates for antibiotic applications.

Physico-Chemical Characterization and Antimicrobial Properties of Hybrid Film Based on Saponite and Phloxine B.

This research was aimed at the preparation of a hybrid film based on a layered silicate saponite (Sap) with the immobilized photosensitizer phloxine B (PhB). Sap was selected because of its high cation exchange capacity, ability to exfoliate into nanolayers, and to modify different surfaces. The X-ray diffraction of the films confirmed the intercalation of both the surfactant and PhB molecules in the Sap film. The photosensitizer retained its photoactivity in the hybrid films, as shown by fluorescence spectra measurements. The water contact angles and the measurement of surface free energy demonstrated the hydrophilic nature of the hybrid films. Antimicrobial effectiveness, assessed by the photodynamic inactivation on hybrid films, was tested against a standard strain and against methicillin-resistant bacteria of Staphylococcus aureus (MRSA). One group of samples was irradiated (green LED light; 2.5 h) and compared to nonirradiated ones. S. aureus strains manifested a reduction in growth from 1-log10 to over 3-log10 compared to the control samples with Sap only, and defects in S. aureus cells were proven by scanning electron microscopy. The results proved the optimal photo-physical properties and anti-MRSA potential of this newly designed hybrid system that reflects recent progress in the modification of surfaces for various medical applications.

The Contribution of Photodynamic Inactivation vs. Corsodyl Mouthwash to the Control of Streptococcus mutans Biofilms.

This work compared the inhibition effect of the commercially available mouthwash Corsodyl, containing 0.1% chlorhexidine digluconate, and photodynamic inactivation (PDI) employing methylene blue (MB) with irradiation from a red laser on 24-h biofilms formed by Streptococcus mutans strains on hydroxyapatite surfaces. The cytotoxicity of Corsodyl and MB was evaluated by Galleria mellonella surviving assay. The viability of biofilm cells after exposure to mouthwash and PDI was determined by counting colony-forming units. The inhibitory effect of antimicrobial agents was confirmed by confocal scanning laser microscopy. MB did not exhibit a cytotoxic effect on larval survival. Non-diluted Corsodyl slightly decreased the survival of larvae. Using our PDI parameters achieved better inhibition than with non-PDI, proving a significant effect on the eradication of S. mutans biofilms and therefore could be an appropriate supplement for the eradication of dental caries.

Activity of anti-CR3-RP polyclonal antibody against biofilms formed by Candida auris, a multidrug-resistant emerging fungal pathogen.

Fungal biofilm has remained a serious medical problem that complicates treatment of mycoses. In particular, once biofilms are formed, they display high levels of resistance against most common antifungals. Candida auris is currently considered as a serious emerging fungal pathogen frequently exhibiting high levels of resistance to antifungals. Recent studies have confirmed that C. auris shares similarity with Candida albicans in regards to virulence-associated proteins involved in adherence and biofilm development. Complement receptor 3-related protein (CR3-RP) is one of the key surface antigens expressed by Candida species during biofilm formation. Here, we have investigated the presence of this cell surface moiety on the surface of C. auris, as well as the potential of anti-CR3-RP polyclonal antibody (Ab) to inhibit biofilm formation by this emerging fungal pathogen. Using indirect immunofluorescence and ELISA, we were able to confirm the presence of CR3-RP in C. auris cells within biofilms. Further, not only anti-CR3-RP Ab was able to inhibit biofilm formation by multiple C. auris strains when added during the adherence phase, but it also demonstrated activity against C. auris 24-h pre-formed biofilms, which compared favorably to levels of inhibition achieved by treatment with current conventional antifungals fluconazole, amphotericin B, and caspofungin. Overall, our data demonstrate the presence of this antigen on the surface of C. auris and points to the potential of anti-CR3-RP Ab in eradication of biofilms formed by this novel fungal pathogen.

Synergy Over Monotherapy.

Pathogenic fungi, as an increasing global threat to human health, represent a sizable risk. However, significant attention should also be paid to the yeast biofilms. One promising strategy for combating resistant microbes, as well as fungal biofilms, is to extend the lifespan and efficacy of our currently employed drugs by using combination therapy. Since the application of combined therapy of fungal infections is currently accepted, we have decided to verify the efficacy of derivative H in combination with fluconazole on C. albicans biofilm. The main advantage of synergy over monotherapy lies in reducing or even completely preventing the induction of resistance of fungal cells. We have decided to verify the derivative H (1,4-dihydropyridine-2,3,5-tricarboxylate), an intermediate of nilvadipine synthesis, in the resistance of C. albicans to fluconazole. Therefore, we have focused on the influence of derivative H on the gene expression of the main C. albicans adhesin (ALS3), which is important for the tissue colonization during the infection process. Our results show that the newly synthesized derivative H had an impact on biofilm eradication. The effect of biofilm diminution could, therefore, be explained as derivative H preventing the adherence of C. albicans cells. This study supports even more the attractiveness of this substance as a potential agent that could be used in synergy with commonly used azoles to treat various fungal infections.

Up-Regulation of Antimicrobial Peptides Gallerimycin and Galiomicin in Galleria mellonella Infected with Candida Yeasts Displaying Different Virulence Traits.

Galleria mellonella has been described as a cheap and an easy-to-reproduce model for the study of fungal infections. We hypothesized that yeasts with higher virulence potential decrease survival and significantly trigger an immune response in G. mellonella through the regulation of innate immunity-related genes encoding antimicrobial peptides (AMPs) such as gallerimycin and galiomicin. Candida albicans SC5314 and Candida dubliniensis CBS 7987, selected because of their different virulence potential, were used for a killing assay followed by the determination of gene expression using qPCR. In vivo results confirmed a significantly (p = 0.0321) lower pathogenicity for C. dubliniensis than for C. albicans. Accordingly, the induction of C. dubliniensis AMPs was lower at all the selected time points post-infection (1 h, 24 h, 48 h). Moreover, we observed an extremely high regulation of the galiomicin gene compared to the gallerimycin one, suggesting a different role of the tested AMPs in protecting G. mellonella from candidiasis.

Employment of methylene blue irradiated with laser light source in photodynamic inactivation of biofilm formed by Candida albicans strain resistant to fluconazole.

A promising approach for the eradication of biofilm formed by the yeast Candida albicans seems to be photodynamic inactivation (PDI). This work presents a use of methylene blue (MB, 1 mM) irradiated with a red laser (output power 190 mW/cm2, wavelength 660 nm) for the eradication of a biofilm formed by the fluconazole-resistant (FLC-resistant) strain C. albicans CY 1123 compared to the standard strain C. albicans SC5314. The periods of irradiation corresponded to the fluence of 15, 23 and 57 J/cm2. Effectiveness of PDI was evident with following percentage of survived biofilm cells: 24.57, 23.46, and 22.29% for SC5314 and 40.28, 17.91, and 5.89% for CY 1123, respectively, compared to the samples without irradiation. Light and confocal laser scanning microscopy confirmed the effectiveness of PDI. However, the morphological form of C. albicans seems to play an important role as well, since prolonged duration of irradiation did not increase efficiency of PDI on C. albicans SC5314. An experiment with the yeast-to-hyphae transition revealed that the FLC-resistant strain expressed a markedly reduced capacity to form hyphae compared to SC5314. We summarized that PDI was effective on biofilm formed by the FLC-resistant strain, but resistance most likely did not play significant role in PDI. Additionally, we observed differences in susceptibility to PDI between biofilms composed of the mycelia and only of the yeasts, and finally, the employment of a laser in PDI enabled a decreasing period of irradiation while maintaining the high effectiveness of PDI.

Synergy between azoles and 1,4-dihydropyridine derivative as an option to control fungal infections.

With emerging fungal infections and developing resistance, there is a need for understanding the mechanisms of resistance as well as its clinical impact while planning the treatment strategies. Several approaches could be taken to overcome the problems arising from the management of fungal diseases. Besides the discovery of novel effective agents, one realistic alternative is to enhance the activity of existing agents. This strategy could be achieved by combining existing antifungal agents with other bioactive substances with known activity profiles (combination therapy). Azole antifungals are the most frequently used class of substances used to treat fungal infections. Fluconazole is often the first choice for antifungal treatment. The aim of this work was to study potential synergy between azoles and 1,4-dihydropyridine-2,3,5-tricarboxylate (termed derivative H) in order to control fungal infections. This article points out the synergy between azoles and newly synthesized derivative H in order to fight fungal infections. Experiments confirmed the role of derivative H as substrate/inhibitor of fungal transporter Cdr1p relating to increased sensitivity to fluconazole. These findings, plus decreased expression of ERG11, are responsible for the synergistic effect.

Humoral immune responses to Candida albicans complement receptor 3-related protein in the atopic subjects with vulvovaginal candidiasis. Novel sensitive marker for Candida infection.

In vitro evaluation of specific anti-Candida albicans sera antibodies based on synthetically prepared complement receptor 3-related protein (CR3-RP) mimicking the structure of native complement receptor 3 in a cohort of 72 patients with atopy and recurrent Candida vulvovaginitis (RVC) revealed effective humoral response against Candida CR3-RP. The most significant have been IgM and IgA isotype antibodies (33 and 47% positive cases, respectively). The quantitative evaluation of anti-CR3RP isotype antibodies was confronted with results of commercial ELISA anti-C. albicans antibodies diagnostics based on C. albicans cell wall mannan and ß-glucan antigens, the most significant correlation being observed with anti-CR3-RP IgM and anti-ß-D-glucan IgM (r(2) = 0.624) followed by isotype IgA (r(2) = 0.381). The immunogenicity and immunoreactivity of CR3RP antigen in RVC patients' sera had been evaluated with regard to the results reached by counterimmunoelectrophoresis and heterogeneous enzyme immunoassay. Obviously, synthetically prepared CR3-RP mimicking the Candida cell-wall-derived structure moiety represents a promising immunological tool not only for Candida serodiagnostics, but also prospectively for follow-up of targeted antifungal therapy and as promising Candida vaccine candidate.

Nanocomposite system with photoactive phloxine B eradicates resistant Staphylococcus aureus.

Nanomaterials modified with hybrid films functionalized with photoactive compounds can be an effective system to prevent and eradicate biofilms on medical devices. The aim of this research was to extend current knowledge on nanomaterial comprised of polyurethane (PU) modified with a nanocomposite film of organoclay with the functionalized photosensitizer (PS) phloxine B (PhB). Particles of the clay mineral saponite were, at first modified by octadecyltrimethylammonium cations to activate the surface for PhB adsorption. The colloids were filtered to get silicate films on polytetrafluoroethylene membrane filters, which were layered with a liquid mixture of PU precursors. The penetration of PU into the silicate formed a thin nanocomposite film. This nanomaterial demonstrated excellent effectiveness against methicillin-resistant S. aureus (MRSA) resistant to fluoroquinolones (L12 and S61, respectively). It showed more than 1000- and 10 000-fold inhibition of biofilm growth after irradiation with green laser compared to the unmodified PU material. Principal component analysis and multiple linear regression showed that the effectiveness of the nanomaterial was not influenced by virulence factors such as the expression of efflux pumps of the Nor family, the adhesin PIA encoded by the icaADBC operon or the robustness of the biofilms. However, the presence of organoclay, PhB and irradiation had a significant effect on the anti-biofilm properties of the nanocomposite. The anti-microbial properties of the material were strengthened after irradiation, because of high reactive oxygen species release (more than 14-fold compared to non-irradiated sample). Materials based on photoactive molecules can represent a worthwhile pathway towards the development of more complex nanomaterials applicable in various fields of medicine.

Galleria mellonella-A Model for the Study of aPDT-Prospects and Drawbacks.

Galleria mellonella is a promising in vivo model insect used for microbiological, medical, and pharmacological research. It provides a platform for testing the biocompatibility of various compounds and the kinetics of survival after an infection followed by subsequent treatment, and for the evaluation of various parameters during treatment, including the host-pathogen interaction. There are some similarities in the development of pathologies with mammals. However, a limitation is the lack of adaptive immune response. Antimicrobial photodynamic therapy (aPDT) is an alternative approach for combating microbial infections, including biofilm-associated ones. aPDT is effective against Gram-positive and Gram-negative bacteria, viruses, fungi, and parasites, regardless of whether they are resistant to conventional treatment. The main idea of this comprehensive review was to collect information on the use of G. mellonella in aPDT. It provides a collection of references published in the last 10 years from this area of research, complemented by some practical experiences of the authors of this review. Additionally, the review summarizes in brief information on the G. mellonella model, its advantages and methods used in the processing of material from these larvae, as well as basic knowledge of the principles of aPDT.

Comparative Analysis of Two Candida parapsilosis Isolates Originating from the Same Patient Harbouring the Y132F and R398I Mutations in the ERG11 Gene.

This work presents a comparative analysis of two clinical isolates of C. parapsilosis, isolated from haemoculture (HC) and central venous catheter (CVC). Both strains harboured Y132F and R398I mutations in the gene ERG11 associated with resistance to fluconazole (FLC). Differences between the HC and CVC isolates were addressed in terms of virulence, resistance to FLC, and lipid distribution. Expression of the ERG6 and ERG9 genes, lipid analysis, fatty acid composition, and lipase activity were assessed via qPCR, thin-layer chromatography/high-performance liquid chromatography, gas chromatography, and spectrophotometry, respectively. Regulation of the ERG6 and ERG9 genes did not prove any impact on FLC resistance. Analysis of lipid metabolism showed a higher accumulation of lanosterol in both the isolates regardless of FLC presence. Additionally, a decreased level of triacylglycerols (TAG) with an impact on the composition of total fatty acids (FA) was observed for both isolates. The direct impact of the ERG11 mutations on lipid/FA analysis has not been confirmed. The higher lipase activity observed for C. parapsilosis HC isolate could be correlated with the significantly decreased level of TAG. The very close relatedness between both the isolates suggests that one isolate was derived from another after the initial infection of the host.

Effect of Quorum Sensing Molecule Farnesol on Mixed Biofilms of Candida albicans and Staphylococcus aureus.

The natural bioactive molecule farnesol (FAR) is widely studied mainly for its antibiofilm and antimicrobial properties. In addition, it increases the effectiveness of some antimicrobial substances, which makes it interesting for the development of combined therapy. In the present work, the effect of FAR either alone or in combination with oxacillin (OXA) on mixed biofilms formed by clinically relevant pathogens, Candida albicans and Staphylococcus aureus, was studied. S. aureus isolates used for biofilm formation originated from blood cultures and central venous catheters (CVC) were characterized in terms of antimicrobial resistance. The minimal biofilm inhibitory concentration (MBIC50) for FAR of 48 h mixed biofilms formed by the C. albicans and methicillin-sensitive S. aureus (MSSA) was determined to be 125 µM, and for the mixed biofilms with methicillin-resistant S. aureus (MRSA) was determined to be 250 µM. Treatment of mixed biofilms with OXA (2 mg/mL) showed ≤4% inhibition; however, the combination of OXA (2 mg/mL) and FAR (300 µM) resulted in 80% inhibition of biofilms. In addition, planktonic cells of S. aureus exhibited an increased susceptibility to OXA, cefoxitin and kanamycin in the presence of FAR (150 and 300 µM). Scanning electron microscopy (SEM) micrographs confirmed patchy biofilm and lack of candidal hyphae in the samples treated with FAR and FAR/OXA in comparison to control and mixed biofilms treated only with OXA. Intriguingly, in a pilot experiment using fluorescence in situ hybridization (FISH), considerable differences in activity (as indicated by ribosome content) of staphylococcal cells were detected. While the activity rate of the staphylococci in mixed biofilms treated with FAR was high, no FISH-positive signal for staphylococcal cells was found in the biofilm treated with FAR/OXA.

Photodynamic Inactivation Effectively Eradicates Candida auris Biofilm despite Its Interference with the Upregulation of CDR1 and MDR1 Efflux Genes.

Candida auris, in recent years, has emerged as a dangerous nosocomial pathogen. It represents a challenge for effective treatment because of its multiresistance. Photodynamic inactivation (PDI) is a promising way to solve problems with a wide range of resistant microorganisms. This study aimed to use PDI for the eradication of C. auris biofilms. Moreover, the regulation of the CDR1, CDR2, and MDR1 resistance genes was studied. Experiments were performed on 24 h biofilms formed by three clinical isolates of C. auris in vitro. PDI was performed in the presence of the photosensitizer methylene blue (0.25 mM) and samples were irradiated with a red laser (λ = 660 nm, 190 mW/cm2) for 79, 120, and 300 s. To confirm the PDI effect, confocal laser scanning microscopy was performed after treatment. Effective PDI was achieved in all strains. The highest inhibition was observed after 300 s irradiation, with over 90% inhibition compared with the non-irradiated control sample. PDI was observed to upregulate the expression of the CDR1 gene, but mainly the MDR1 gene. Despite this observation, PDI significantly decreased the survival of C. auris biofilm cells and proved to have great potential for the eradication of problematic resistant yeasts.

Persistence and multi-ward dissemination of vancomycin-resistant Enterococcus faecium ST17 clone in hospital settings in Slovakia 2017-2020.

OBJECTIVES: Hospital vancomycin-resistant Enterococcus faecium (VREfm) were evaluated in term of resistance and phylogenetic relatedness to estimate the location and possible route of transmission of resistance determinants. METHODS: Hospital VREfm (n = 49) were collected in the northern part of Slovakia during 2017-2020. The collection was analysed for the presence of the van operon and 10 representatives were subjected to whole-genome sequencing using Illumina MiSeq platform. Obtained sequences were de novo assembled and the draft genome assemblies were analysed with respect to sequence type (ST), plasmid content, resistance and virulence genes, and the phylogenetic relatedness in single nucleotide polymorphisms (SNP). RESULTS: All strains possessed the vanA operon. Ten selected evaluated isolates belonged to the clinically relevant clonal complex (CC) 17 and carried the vanHAX gene cluster conferring vancomycin resistance on mobile genetic elements, except for the isolate M17773 carrying the vanHAX gene cluster chromosomally. All isolates encoded resistance to quinolones (gyrA and parC mutations) and aminoglycosides [aac(6')-aph(2'')]. Four isolates from different wards and patients belonging to ST17 were closely related (6-50 SNP), suggesting long-term persistence of VREfm ST17 in hospital settings. CONCLUSION: VREfm proved to harbour many genetic determinants of antimicrobial resistance. The plasmids carrying the vanA genes belonged to the conjugative broad-host families Inc18 and RepA_N, posing a threat to human health, especially in hospital settings. Moreover, four clinical isolates were phylogenetically related, pointing towards stable circulation of the ST17 VREfm clone in the hospital setting and underlining the necessity for continuous surveillance of glycopeptide-resistant pathogens.

Farnesol Boosts the Antifungal Effect of Fluconazole and Modulates Resistance in Candida auris through Regulation of the CDR1 and ERG11 Genes.

Candida auris is considered a serious fungal pathogen frequently exhibiting a high resistance to a wide range of antifungals. In this study, a combination of the quorum-sensing molecule farnesol (FAR) and fluconazole (FLU) was tested on FLU-resistant C. auris isolates (C. auris S and C. auris R) compared to the susceptible C. auris H261. The aim was to assess the possible synergy between FAR and FLU, by reducing the FLU minimal inhibitory concentration, and to determine the mechanism underlying the conjunct effect. The results confirmed a synergic effect between FAR and FLU with a calculated FIC index of 0.75 and 0.4 for C. auris S and C. auris R, respectively. FAR modulates genes involved in azole resistance. When FAR was added to the cells in combination with FLU, a significant decrease in the expression of the CDR1 gene was observed in the resistant C. auris isolates. FAR seems to block the Cdr1 efflux pump triggering a restoration of the intracellular content of FLU. These results were supported by observed increasing accumulation of rhodamine 6G by C. auris cells. Moreover, C. auris treated with FAR showed an ERG11 gene down-regulation. Overall, these results suggest that FAR is an effective modulator of the Cdr1 efflux pump in C. auris and, in combination with FLU, enhances the activity of this azole, which might be a promising strategy to control infections caused by azole-resistant C. auris.

Antimicrobial Resistance and Biofilms Underlying Catheter-Related Bloodstream Coinfection by Enterobacter cloacae Complex and Candida parapsilosis.

Biofilm-associated infections are a public health concern especially in the context of healthcare-associated infections such as catheter-related bloodstream infections (CRBSIs). We evaluated the biofilm formation and antimicrobials resistance (AMR) of Enterobacter cloacae complex and Candida parapsilosis co-isolated from a CRBSI patient. Antimicrobial susceptibility of central venous catheters (CVCs) and hemoculture (HC) isolates was evaluated, including whole genome sequencing (WGS) resistome analysis and evaluation of gene expression to obtain insight into their AMR determinants. Crystal violet assay was used to assess dual biofilm biomass and microscopy was used to elucidate a microorganism's distribution within biofilms assembled on different materials. Bacteria were multidrug-resistant including resistance to colistin and beta-lactams, likely linked to the mcr-9-like phosphoethanolamine transferase and to an ACT family cephalosporin-hydrolyzing class C beta-lactamase, respectively. The R398I and Y132F mutations in the ERG11 gene and its differential expression might account for C. parapsilosis resistance to fluconazole. The phenotype of dual biofilms assembled on glass, polystyrene and polyurethane depends on the material and how biofilms were initiated by one or both pathogens. Biofilms assembled on polyurethane were denser and richer in the extracellular polymeric matrix, and microorganisms were differently distributed on the inner/outer surface of the CVC.

Cdr2p contributes to fluconazole resistance in Candida dubliniensis clinical isolates.

The development of resistance to azole antifungals used in the treatment of fungal infections can be a serious medical problem. Here, we investigate the molecular mechanisms associated with reduced susceptibility to fluconazole in clinical isolates of Candida dubliniensis , showing evidence of the trailing growth phenomenon. The changes in membrane sterol composition were studied in the presence of subinhibitory fluconazole concentrations. Despite lanosterol and eburicol accumulating as the most prevalent sterols after fluconazole treatment, these ergosterol precursors still support growth of Candida isolates. The overexpression of ABC transporters was demonstrated by immunoblotting employing specific antibodies against Cdr1p and Cdr2p. The presence of a full-length 170 kDa protein Cdr1p was detected in two isolates, while a truncated form of Cdr1p with the molecular mass of 85 kDa was observed in isolate 966/3(2). Notably, Cdr2p was detected in this isolate, and the expression of this transporter was modulated by subinhibitory concentrations of fluconazole. These results suggest that C. dubliniensis can display the trailing growth phenomenon, and such isolates express similar molecular mechanisms like that of fluconazole-resistant isolates and can therefore be associated with recurrent infections.

Impact of Healthcare-Associated Infections Connected to Medical Devices-An Update.

Healthcare-associated infections (HAIs) are caused by nosocomial pathogens. HAIs have an immense impact not only on developing countries but also on highly developed parts of world. They are predominantly device-associated infections that are caused by the planktonic form of microorganisms as well as those organized in biofilms. This review elucidates the impact of HAIs, focusing on device-associated infections such as central line-associated bloodstream infection including catheter infection, catheter-associated urinary tract infection, ventilator-associated pneumonia, and surgical site infections. The most relevant microorganisms are mentioned in terms of their frequency of infection on medical devices. Standard care bundles, conventional therapy, and novel approaches against device-associated infections are briefly mentioned as well. This review concisely summarizes relevant and up-to-date information on HAIs and HAI-associated microorganisms and also provides a description of several useful approaches for tackling HAIs.