Candida/Staphylococcal Polymicrobial Intra-Abdominal Infection: Pathogenesis and Perspectives for a Novel Form of Trained Innate Immunity

Modulation of myeloid-derived suppressor cell functions by oral inflammatory diseases and important oral pathogens

The oral cavity presents a diverse microbiota in a dynamic balance with the host. Disruption of the microbial community can promote dysregulation of local immune response which could generate oral diseases. Additionally, alterations in host immune system can result in inflammatory disorders. Different microorganisms have been associated with establishment and progression of the oral diseases. Oral cavity pathogens/diseases can modulate components of the inflammatory response. Myeloid-derived suppressor cells (MDSCs) own immunoregulatory functions and have been involved in different inflammatory conditions such as infectious processes, autoimmune diseases, and cancer. The aim of this review is to provide a comprehensive overview of generation, phenotypes, and biological functions of the MDSCs in oral inflammatory diseases. Also, it is addressed the biological aspects of MDSCs in presence of major oral pathogens. MDSCs have been mainly analyzed in periodontal disease and Sjögren's syndrome and could be involved in the outcome of these diseases. Studies including the participation of MDSCs in other important oral diseases are very scarce. Major oral bacterial and fungal pathogens can modulate expansion, subpopulations, recruitment, metabolism, immunosuppressive activity and osteoclastogenic potential of MDSCs. Moreover, MDSC plasticity is exhibited in presence of oral inflammatory diseases/oral pathogens and appears to be relevant in the disease progression and potentially useful in the searching of possible treatments. Further analyses of MDSCs in oral cavity context could allow to understand the contribution of these cells in the fine-tuned balance between host immune system and microorganism of the oral biofilm, as well as their involvement in the development of oral diseases when this balance is altered.

Candida-induced granulocytic myeloid-derived suppressor cells are protective against polymicrobial sepsis

IMPORTANCE

Polymicrobial intra-abdominal infections are serious clinical infections that can lead to life-threatening sepsis, which is difficult to treat in part due to the complex and dynamic inflammatory responses involved. Our prior studies demonstrated that immunization with low-virulence Candida species can provide strong protection against lethal polymicrobial sepsis challenge in mice. This long-lived protection was found to be mediated by trained Gr-1+ polymorphonuclear leukocytes with features resembling myeloid-derived suppressor cells (MDSCs). Here we definitively characterize these cells as MDSCs and demonstrate that their mechanism of protection involves the abrogation of lethal inflammation, in part through the action of the anti-inflammatory cytokine interleukin (IL)-10. These studies highlight the role of MDSCs and IL-10 in controlling acute lethal inflammation and give support for the utility of trained tolerogenic immune responses in the clinical treatment of sepsis.

Critical appraisal beyond clinical guidelines for intraabdominal candidiasis

BACKGROUND

Regardless of the available antifungals, intraabdominal candidiasis (IAC) mortality continues to be high and represents a challenge for clinicians.

MAIN BODY

This opinion paper discusses alternative antifungal options for treating IAC. This clinical entity should be addressed separately from candidemia due to the peculiarity of the required penetration of antifungals into the peritoneal cavity. Intraabdominal concentrations may be further restricted in critically ill patients where pathophysiological facts alter normal drug distribution. Echinocandins are recommended as first-line treatment in guidelines for invasive candidiasis. However, considering published data, our pharmacodynamic analysis suggests the required increase of doses, postulated by some authors, to attain adequate pharmacokinetic (PK) levels in peritoneal fluid. Given the limited evidence in the literature on PK/PD-based treatments of IAC, an algorithm is proposed to guide antifungal treatment. Liposomal amphotericin B is advocated as first-line therapy in patients with sepsis/septic shock presenting candidemia or endophthalmitis, or with prior exposure to echinocandins and/or fluconazole, or with infections by Candida glabrata. Other situations and alternatives, such as new compounds or combination therapy, are also analysed.

CONCLUSION

There is a critical need for more robust clinical trials, studies examining patient heterogeneity and surveillance of antifungal resistance to enhance patient care and optimise treatment outcomes. Such evidence will help refine the existing guidelines and contribute to a more personalised and effective approach to treating this serious medical condition. Meanwhile, it is suggested to broaden the consideration of other options, such as liposomal amphotericin B, as first-line treatment until the results of the fungogram are available and antifungal stewardship could be implemented to prevent the development of resistance.

Myeloid-derived suppressor cells and pulmonary hypertension

Pulmonary hypertension (PH) is a chronic pulmonary vascular disorder characterized by an increase in pulmonary vascular resistance and pulmonary arterial pressure. The detailed molecular mechanisms remain unclear. In recent decades, increasing evidence shows that altered immune microenvironment, comprised of immune cells, mesenchymal cells, extra-cellular matrix and signaling molecules, might induce the development of PH. Myeloid-derived suppressor cells (MDSCs) have been proposed over 30 years, and the functional importance of MDSCs in the immune system is appreciated recently. MDSCs are a heterogeneous group of cells that expand during cancer, chronic inflammation and infection, which have a remarkable ability to suppress T-cell responses and may exacerbate the development of diseases. Thus, targeting MDSCs has become a novel strategy to overcome immune evasion, especially in tumor immunotherapy. Nowadays, severe PH is accepted as a cancer-like disease, and MDSCs are closely related to the development and prognosis of PH. Here, we review the relationship between MDSCs and PH with respect to immune cells, cytokines, chemokines and metabolism, hoping that the key therapeutic targets of MDSCs can be identified in the treatment of PH, especially in severe PH.

Efficacy of Candida dubliniensis and Fungal β-Glucans in Inducing Trained Innate Immune Protection Against Inducers of Sepsis

Fungal-bacterial intra-abdominal infections (IAI) can lead to sepsis with significant morbidity and mortality. We have established a murine model of Candida albicans (Ca) and Staphylococcus aureus (Sa) IAI that results in acute lethal sepsis. Prior intraperitoneal or intravenous inoculation with low virulence Candida dubliniensis (Cd) confers high level protection against lethal Ca/Sa IAI and sepsis. Protection via Cd immunization is associated with decreased pro-inflammatory cytokines and mediated by Gr-1⁺ putative myeloid-derived suppressor cells (MDSCs) representing a novel form of trained innate immunity (TII). The objective of these studies was to determine the extent of Cd-mediated TII against sepsis of broad origin and explore the potential of fungal cell wall components as abiotic immunogen alternatives to induce TII, including zymosan depleted of TLR2 activity (d-zymosan), or purified preparations of β-glucan. Immunized mice were challenged 14 days post-immunization with a lethal array of live or abiotic inducers of sepsis, including Ca/Sa, Ca/Escherichia coli (Ca/Ec), LPS or untreated zymosan. Results showed that live Cd immunization was protective against sepsis induced by Ca/Ec and zymosan, but not LPS. Similar to protection against Ca/Sa, survival was dependent on Gr-1+ cells with no role for macrophages. Among the fungal cell wall compounds as immunogens, immunization with d-zymosan and an alkali-treated form of β-glucan also resulted in significant protection against sepsis induced by Ca/Sa or Ca/Ec, but not LPS sepsis. Again, there was a strong dependence on Gr-1+ cells for protection with one exception, an added role for macrophages in the case of protection induced by alkali-treated β-glucan. Overall, these results demonstrate that immunization with Cd as well as abiotic fungal cell components are capable of Gr-1+ cell-mediated trained innate immune protection against sepsis of broad microbial origin. In addition, abiotic β-glucans represent potential alternatives to live Cd for protection against lethal polymicrobial sepsis.

Revisiting the potential role of BCG and MMR vaccines in COVID-19

Despite the development and deployment of effective COVID-19 vaccines, many regions remain poorly covered. Seeking alternative tools for achieving immunity against COVID-19 remains to be of high importance. "Trained immunity" is the nonspecific immune response usually established through administering live attenuated vaccines and is a potential preventive tool against unrelated infections. Evidence regarding a possible protective role for certain live attenuated vaccines against COVID-19 has emerged mainly for those administered as part of childhood vaccination protocols. This review summarizes the relevant literature about the potential impact of Bacille Calmette-Guérin (BCG) and measles, mumps and rubella (MMR) vaccines on COVID-19. Existing available data suggest a potential role for BCG and MMR in reducing COVID-19 casualties and burden. However, more investigation and comparative studies are required for a better understanding of their impact on COVID-19 outcomes.

Role of myeloid derived suppressor cells in sepsis

Sepsis is a serious and menacing organ dysfunction that occur due to dysregulated response of the host towards the infection. This organ dysfunction may lead to sepsis with intense cellular, metabolic and circulatory dysregulation, multiple organ failure and high mortality. Lymphopenia is observed in two-third of sepsis patients and a significant depletion of lymphocytes occurs in non-survivors compared to sepsis survivors. Myeloid derived suppressor cells (MDSCs) gave new insights into sepsis-associated lymphopenia. If MDSC expansion and its tissue-infiltration persist, it can induce significant pathophysiology including lymphopenia, host immunosuppression and immune-paralysis that contributes to worsened patient outcomes. This review focuses on MDSCs and its subsets, the role of MDSCs in infection, sepsis and septic shock.

Enhanced Virulence of Candida albicans by Staphylococcus aureus: Evidence in Clinical Bloodstream Infections and Infected Zebrafish Embryos

Coinfection with Candida and Staphylococcus results in higher mortality in animal studies. However, the pathogenesis and interplay between C. albicans and S. aureus in bloodstream infections (BSIs) is unclear. This study determines the clinical features and outcomes of mixed C. albicans/S. aureus (CA/SA) BSIs and biofilm formation on pathogenesis during coinfection. Demographics and outcomes for mixed BSIs and monomicrobial candidemia were compared. Compared to 115 monomicrobial C. albicans BSIs, 22 patients with mixed CA/SA BSIs exhibited a significantly higher mortality rate and shorter survival time. In vitro and in vivo biofilm analysis showed that C. albicans accounted for the main biofilm architecture, and S. aureus increased its amount. Antibiotic tolerance in S. aureus, which adhered to Candida hyphae observed by scanning electron microscope, was demonstrated by the presence of wild-type C. albicans co-biofilm. Upregulation in exotoxin genes of S. aureus was evidenced by quantitative RT-PCR when a co-biofilm was formed with C. albicans. Mixed CA/SA BSIs result in a higher mortality rate in patients and in vivo surrogate models experiments. This study demonstrates that the virulence enhancement of C. albicans and S. aureus during co-biofilm formation contributes to the high mortality rate.

Metabolic Adaptations During Staphylococcus aureus and Candida albicans Co-Infection

Successful pathogens require metabolic flexibility to adapt to diverse host niches. The presence of co-infecting or commensal microorganisms at a given infection site can further influence the metabolic processes required for a pathogen to cause disease. The Gram-positive bacterium Staphylococcus aureus and the polymorphic fungus Candida albicans are microorganisms that asymptomatically colonize healthy individuals but can also cause superficial infections or severe invasive disease. Due to many shared host niches, S. aureus and C. albicans are frequently co-isolated from mixed fungal-bacterial infections. S. aureus and C. albicans co-infection alters microbial metabolism relative to infection with either organism alone. Metabolic changes during co-infection regulate virulence, such as enhancing toxin production in S. aureus or contributing to morphogenesis and cell wall remodeling in C. albicans. C. albicans and S. aureus also form polymicrobial biofilms, which have greater biomass and reduced susceptibility to antimicrobials relative to mono-microbial biofilms. The S. aureus and C. albicans metabolic programs induced during co-infection impact interactions with host immune cells, resulting in greater microbial survival and immune evasion. Conversely, innate immune cell sensing of S. aureus and C. albicans triggers metabolic changes in the host cells that result in an altered immune response to secondary infections. In this review article, we discuss the metabolic programs that govern host-pathogen interactions during S. aureus and C. albicans co-infection. Understanding C. albicans-S. aureus interactions may highlight more general principles of how polymicrobial interactions, particularly fungal-bacterial interactions, shape the outcome of infectious disease. We focus on how co-infection alters microbial metabolism to enhance virulence and how infection-induced changes to host cell metabolism can impact a secondary infection.

Trained Innate Immunity Induced by Vaccination with Low-Virulence Candida Species Mediates Protection against Several Forms of Fungal Sepsis via Ly6G+ Gr-1+ Leukocytes

We recently discovered a novel form of trained innate immunity (TII) induced by low-virulence Candida species (i.e., Candida dubliniensis) that protects against lethal fungal/bacterial infection. Mice vaccinated by intraperitoneal (i.p.) inoculation are protected against lethal sepsis following Candida albicans/Staphylococcus aureus (Ca/Sa) intra-abdominal infection (IAI) or Ca bloodstream infection (BSI). The protection against IAI is mediated by long-lived Gr-1⁺ leukocytes as putative myeloid-derived suppressor cells (MDSCs) and not by prototypical trained macrophages. This study aimed to determine if a similar TII mechanism (Gr-1⁺ cell-mediated suppression of sepsis) is protective against BSI and whether this TII can also be induced following intravenous (i.v.) vaccination. For this, mice were vaccinated with low-virulence Candida strains (i.p. or i.v.), followed by lethal challenge (Ca/Sa i.p. or Ca i.v.) 14 days later, and observed for sepsis (hypothermia, sepsis scoring, and serum cytokines), organ fungal burden, and mortality. Similar parameters were monitored following depletion of macrophages or Gr-1⁺ leukocytes during lethal challenge. The results showed that mice vaccinated i.p. or i.v. were protected against lethal Ca/Sa IAI or Ca BSI. In all cases, protection was mediated by Ly6G⁺ Gr-1⁺ putative granulocytic MDSCs (G-MDSCs), with no role for macrophages, and correlated with reduced sepsis parameters. Protection also correlated with reduced fungal burden in spleen and brain but not liver or kidney. These results suggest that Ly6G⁺ G-MDSC-mediated TII is induced by either the i.p. and i.v. route of inoculation and protects against IAI or BSI forms of systemic candidiasis, with survival correlating with amelioration of sepsis and reduced organ-specific fungal burden. IMPORTANCE Trained innate immunity (TII) is induced following immunization with live attenuated microbes and represents a clinically important strategy to enhance innate defenses. TII was initially demonstrated following intravenous inoculation with low-virulence Candida albicans, with protection against a subsequent lethal C. albicans intravenous bloodstream infection (BSI) mediated by monocytes with enhanced cytokine responses. We expanded this by describing a novel form of TII induced by intraperitoneal inoculation with low-virulence Candida that protects against lethal sepsis induced by polymicrobial intra-abdominal infection (IAI) via Gr-1⁺ leukocytes as putative myeloid-derived suppressor cells (MDSCs). In this study, we addressed these two scenarios and confirmed an exclusive role for Ly6G⁺ Gr-1⁺ leukocytes in mediating TII against either IAI or BSI via either route of inoculation, with protection associated with suppression of sepsis. These studies highlight the previously unrecognized importance of Ly6G⁺ MDSCs as central mediators of a novel form of TII termed trained tolerogenic immunity.

Oral Epithelial Cells Distinguish between Candida Species with High or Low Pathogenic Potential through MicroRNA Regulation

Oral epithelial cells monitor microbiome composition and initiate immune response upon dysbiosis, as in the case of Candida imbalances. Candida species, such as C. albicans and C. parapsilosis, are the most prevalent yeasts in the oral cavity. Comparison of healthy oral epithelial cell responses revealed that while C. albicans infection robustly activated inflammation cascades, C. parapsilosis primarily activated various inflammation-independent pathways. In posttranscriptional regulatory processes, several miRNAs were altered by both species. For C. parapsilosis, the dose of yeast cells directly correlated with changes in transcriptomic responses with higher fungal burdens inducing significantly different and broader changes. MicroRNAs (miRNAs) associated with carbohydrate metabolism-, hypoxia-, and vascular development-related responses dominated with C. parapsilosis infection, whereas C. albicans altered miRNAs linked to inflammatory responses. Subsequent analyses of hypoxia-inducible factor 1α (HIF1-α) and hepatic stellate cell (HSC) activation pathways predicted target genes through which miRNA-dependent regulation of yeast-specific functions may occur, which also supported the observed species-specific responses. Our findings suggest that C. parapsilosis is recognized as a commensal at low doses by the oral epithelium; however, increased fungal burden activates different pathways, some of which overlap with the inflammatory processes robustly induced by C. albicans IMPORTANCE A relatively new topic within the field of immunology involves the role of miRNAs in innate as well as adaptive immune response regulation. In recent years, posttranscriptional regulation of host-pathogenic fungal interactions through miRNAs was also suggested. Our study reveals that the distinct nature of human oral epithelial cell responses toward C. parapsilosis and C. albicans is possibly due to species-specific fine-tuning of host miRNA regulatory processes. The findings of this study also shed new light on the nature of early host cell transcriptional responses to the presence of C. parapsilosis and highlight the species' potential inflammation-independent host activation processes. These findings contribute to our better understanding of how miRNA deregulation at the oral immunological barrier, in noncanonical immune cells, may discriminate between fungal species, particularly Candida species with high or low pathogenic potential.

Myeloid cell dynamics correlating with clinical outcomes of severe COVID-19 in Japan

An expanded myeloid cell compartment is a hallmark of severe coronavirus disease 2019 (COVID-19). However, data regarding myeloid cell expansion have been collected in Europe, where the mortality rate by COVID-19 is greater than those in other regions including Japan. Thus, characteristics of COVID-19-induced myeloid cell subsets remain largely unknown in the regions with low mortality rates. Here, we analyzed cellular dynamics of myeloid-derived suppressor cell (MDSC) subsets and examined whether any of them correlate with disease severity and prognosis, using blood samples from Japanese COVID-19 patients. We observed that polymorphonuclear (PMN)-MDSCs, but not other MDSC subsets, transiently expanded in severe cases but not in mild or moderate cases. Contrary to previous studies in Europe, this subset selectively expanded in survivors of severe cases and subsided before discharge, but such transient expansion was not observed in non-survivors in Japanese cohort. Analysis of plasma cytokine/chemokine levels revealed positive correlation of PMN-MDSC frequencies with interleukin 8 (IL-8) levels prior to the cell expansion, indicating the involvement of IL-8 on recruitment of PMN-MDSCs to peripheral blood following the onset of severe COVID-19. Thus, our data indicates that transient expansion of the PMN-MDSC subset results in improved clinical outcome. Thus, this myeloid cell subset may be a predictor of prognosis in cases of severe COVID-19 in Japan.

Targeting pathogenic fungi, bacteria and fungal-bacterial biofilms by newly synthesized quaternary ammonium derivative of pyridoxine and terbinafine with dual action profile

Many pathogenic bacteria and microscopic fungi form rigid polymicrobial biofilms this way enhancing their resistant to treatment. A series of novel pyridoxine-based quaternary ammonium derivatives of terbinafine characterized by both antifungal and antibacterial activities was designed. The leading compound named KFU-127 exhibits promising antifungal and antibacterial activities against various bacteria and micromycetes in both planktonic and biofilm-embedded forms demonstrating MIC values comparable with those of conventional antifungals and antimicrobials. Similar to other antiseptics like benzalkonium chloride and miramistin, KFU-127 is considerably toxic for eukaryotic cells that limits is application to topical treatment options. On the other hand, KFU-127 reduces the number of viable biofilm-embedded bacteria and C. albicans by 3 orders of magnitude at concentrations 2-4 times lower than those of reference drugs and successfully eradicates S. aureus-C. albicans mixed biofilms. The mechanism of antimicrobial action of KFU-127 is bimodal including both membrane integrity damage and pyridoxal-dependent enzymes targeting. We expect that this bilateral mechanism would result in lower rates of resistance development in both fungal and bacterial pathogens. Taken together, our data suggest KFU-127 as a new promising broad spectrum topical antimicrobial capable of one-shot targeting of bacterial and fungal-bacterial biofilms.

Could an Unrelated Live Attenuated Vaccine Serve as a Preventive Measure To Dampen Septic Inflammation Associated with COVID-19 Infection?

We propose the concept that administration of an unrelated live attenuated vaccine, such as MMR (measles, mumps, rubella), could serve as a preventive measure against the worst sequelae of coronavirus disease 2019 (COVID-19). There is mounting evidence that live attenuated vaccines provide nonspecific protection against lethal infections unrelated to the target pathogen of the vaccine by inducing "trained" nonspecific innate immune cells for improved host responses against subsequent infections. Mortality in COVID-19 cases is strongly associated with progressive lung inflammation and eventual sepsis. Vaccination with MMR in immunocompetent individuals has no contraindications and may be especially effective for health care workers who can easily be exposed to COVID-19. Following the lead of other countries conducting clinical trials with the live attenuated Mycobacterium bovis BCG (BCG) vaccine under a similar concept, a clinical trial with MMR in high-risk populations may provide a "low-risk-high-reward" preventive measure in saving lives during this unprecedented COVID-19 pandemic.

Candida Biofilms: An Update on Developmental Mechanisms and Therapeutic Challenges

Fungi of the genus Candida are important etiological agents of superficial and life-threatening infections in individuals with a compromised immune system. One of the main characteristics of Candida is its ability to form highly drug tolerance biofilms in the human host. Biofilms are a dynamic community of multiple cell types whose formation over time is orchestrated by a network of transcription regulators. In this brief review, we provide an update of the processes involved in biofilm formation by Candida spp. (formation, treatment, and control), as well as the transcriptional circuitry that regulates its development and interactions with other microorganisms. Candida albicans is known to build mixed species biofilms with other Candida species and with various other bacterial species in different host niches. Taken together, these properties play a key role in Candida pathogenesis. In addition, this review gathers recent studies with new insights and perspectives for the treatment and control of Candida biofilms.

Applying the Host-Microbe Damage Response Framework to Candida Pathogenesis: Current and Prospective Strategies to Reduce Damage

Disease is a complex outcome that can occur as a result of pathogen-mediated damage, host-mediated damage or both. This has led to the revolutionary concept of the damage response framework (DRF) that defines microbial virulence as a function of host immunity. The DRF outlines six scenarios (classes) of host damage or beneficial outcomes, depending on the microbe and the strength of the immune response. Candida albicans is uniquely adapted to its human host and can exist as either a commensal, colonizing various anatomical sites without causing notable damage, or as a pathogen, with the ability to cause a diverse array of diseases, ranging from mucosal to invasive systemic infections that result in varying levels of microbe-mediated and/or host-mediated damage. We recently categorized six different forms of candidiasis (oropharyngeal, hematogenous, intra-abdominal, gastrointestinal, denture stomatitis, and vulvovaginitis) into independent DRF classes, supporting a contemporary view of unique mechanisms of pathogenesis for these Candida infections. In this review, we summarize the evidence for the pathogenesis of these various forms of candidiasis in the context of the DRF with the further intent to provide insights into strategies to achieve a level of host response or outcome otherwise, that limits host damage.

Sanguinarine Inhibits Mono- and Dual-Species Biofilm Formation by Candida albicans and Staphylococcus aureus and Induces Mature Hypha Transition of C. albicans

Previous studies have reported that sanguinarine possesses inhibitory activities against several microorganisms, but its effects on mono- and dual-species biofilms of C. albicans and S. aureus have not been fully elucidated. In this study, we aimed to evaluate the efficacy of sanguinarine for mono- and dual-species biofilms and explore its ability to induce the hypha-to-yeast transition of C. albicans. The results showed that the minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC90) of sanguinarine against C. albicans and S. aureus mono-species biofilms was 4, and 2 μg/mL, respectively, while the MIC and MBIC90 of sanguinarine against dual-species biofilms was 8, and 4 μg/mL, respectively. The decrease in the levels of matrix component and tolerance to antibiotics of sanguinarine-treated mono- and dual-species biofilms was revealed by confocal laser scanning microscopy combined with fluorescent dyes, and the gatifloxacin diffusion assay, respectively. Meanwhile, sanguinarine at 128 and 256 μg/mL could efficiently eradicate the preformed 24-h biofilms by mono- and dual-species, respectively. Moreover, sanguinarine at 8 μg/mL could result in the transition of C. albicans from the mature hypha form to the unicellular yeast form. Hence, this study provides useful information for the development of new agents to combat mono- and dual-species biofilm-associated infections, caused by C. albicans and S. aureus.

Candida albicans and Staphylococcus Species: A Threatening Twosome

Candida albicans and Staphylococcus species are, respectively, the most common fungal and bacterial agents isolated from bloodstream infections, worldwide. Moreover, it has been shown that 20% of all C. albicans bloodstream infections are polymicrobial in nature, with Staphylococcus epidermidis and Staphylococcus aureus being the first and third most common co-isolated organisms, respectively. These species are part of the commensal microbial flora but can cause hospital-acquired infections with an extreme ability to inhabit diverse host niches, especially in immunocompromised patients. They are well known for their ability to form persistent biofilms in the host or on abiotic surfaces such as indwelling medical devices. Interactions within these biofilm communities can lead to increased virulence, drug tolerance, and immune evasion. This can ultimately impact morbidity and infection outcome, often leading to an increased mortality. Therefore, characterizing the interactions between these species could lead to the development of novel therapeutic approaches that target polymicrobial infections. In this mini review, we briefly highlight the current knowledge and most recent insights into the complex interspecies interactions of C. albicans with Staphylococcus bacteria.