Candida dubliniensis fungemia: the first four cases in North America

Risk factors and outcomes associated with community-onset and hospital-acquired coinfection in patients hospitalized for coronavirus disease 2019 (COVID-19): A multihospital cohort study

Background:

We sought to determine the incidence of community-onset and hospital-acquired coinfection in patients hospitalized with coronavirus disease 2019 (COVID-19) and to evaluate associated predictors and outcomes.

Methods:

In this multicenter retrospective cohort study of patients hospitalized for COVID-19 from March 2020 to August 2020 across 38 Michigan hospitals, we assessed prevalence, predictors, and outcomes of community-onset and hospital-acquired coinfections. In-hospital and 60-day mortality, readmission, discharge to long-term care facility (LTCF), and mechanical ventilation duration were assessed for patients with versus without coinfection.

Results:

Of 2,205 patients with COVID-19, 141 (6.4%) had a coinfection: 3.0% community onset and 3.4% hospital acquired. Of patients without coinfection, 64.9% received antibiotics. Community-onset coinfection predictors included admission from an LTCF (OR, 3.98; 95% CI, 2.34–6.76; P < .001) and admission to intensive care (OR, 4.34; 95% CI, 2.87–6.55; P < .001). Hospital-acquired coinfection predictors included fever (OR, 2.46; 95% CI, 1.15–5.27; P = .02) and advanced respiratory support (OR, 40.72; 95% CI, 13.49–122.93; P < .001). Patients with (vs without) community-onset coinfection had longer mechanical ventilation (OR, 3.31; 95% CI, 1.67–6.56; P = .001) and higher in-hospital mortality (OR, 1.90; 95% CI, 1.06–3.40; P = .03) and 60-day mortality (OR, 1.86; 95% CI, 1.05–3.29; P = .03). Patients with (vs without) hospital-acquired coinfection had higher discharge to LTCF (OR, 8.48; 95% CI, 3.30–21.76; P < .001), in-hospital mortality (OR, 4.17; 95% CI, 2.37–7.33; P ≤ .001), and 60-day mortality (OR, 3.66; 95% CI, 2.11–6.33; P ≤ .001).

Conclusion:

Despite community-onset and hospital-acquired coinfection being uncommon, most patients hospitalized with COVID-19 received antibiotics. Admission from LTCF and to ICU were associated with increased risk of community-onset coinfection. Future studies should prospectively validate predictors of COVID-19 coinfection to facilitate the reduction of antibiotic use.

New and Promising Chemotherapeutics for Emerging Infections Involving Drug-resistant Non-albicans Candida Species

Fungal infections are a veritable public health problem worldwide. The increasing number of patient populations at risk (e.g. transplanted individuals, cancer patients, and HIV-infected people), as well as the use of antifungal agents for prophylaxis in medicine, have favored the emergence of previously rare or newly identified fungal species. Indeed, novel antifungal resistance patterns have been observed, including environmental sources and the emergence of simultaneous resistance to different antifungal classes, especially in Candida spp., which are known for the multidrug-resistance (MDR) profile. In order to circumvent this alarming scenario, the international researchers' community is engaged in discovering new, potent, and promising compounds to be used in a near future to treat resistant fungal infections in hospital settings on a global scale. In this context, many compounds with antifungal action from both natural and synthetic sources are currently under clinical development, including those that target either ergosterol or β(1,3)-D-glucan, presenting clear evidence of pharmacologic/pharmacokinetic advantages over currently available drugs against these two well-known fungal target structures. Among these are the tetrazoles VT-1129, VT-1161, and VT-1598, the echinocandin CD101, and the glucan synthase inhibitor SCY-078. In this review, we compiled the most recent antifungal compounds that are currently in clinical trials of development and described the potential outcomes against emerging and rare Candida species, with a focus on C. auris, C. dubliniensis, C. glabrata, C. guilliermondii, C. haemulonii, and C. rugosa. In addition to possibly overcoming the limitations of currently available antifungals, new investigational chemical agents that can enhance the classic antifungal activity, thereby reversing previously resistant phenotypes, were also highlighted. While novel and increasingly MDR non-albicans Candida species continue to emerge worldwide, novel strategies for rapid identification and treatment are needed to combat these life-threatening opportunistic fungal infections.

First Reported Case of Candida dubliniensis Endocarditis Related to Implantable Cardioverter-Defibrillator

A 36-year-old male presented to the ED with acute chronic hyponatremia found on routine weekly lab work with one-week history of generalized weakness, confusion, nausea/vomiting, and diarrhea. The patient has nonischemic cardiomyopathy of unknown etiology diagnosed in his teens with an AICD device placed 8 years ago and receiving milrinone infusion 3 years ago via peripherally inserted central catheter (PICC) line. Two sets of blood cultures grew Candida dubliniensis. The patient was started on micafungin and the PICC line was removed and replaced with a central line. A transthoracic echocardiogram (TEE) showed findings consistent with AICD lead involvement. The patient was continued on treatment for fungal infective endocarditis and transferred to another hospital where he had successful AICD lead extraction. Blood cultures upon transfer back to our facility were positive for methicillin-sensitive Staphylococcus aureus (MSSA). This bacteremia was thought to be secondary to right-sided internal jugular (IJ) central line and resolved with line removal and initiation of intravenous (IV) cefazolin. The patient was discharged on IV cefazolin and IV micafungin. He had a LifeVest® until completion of his antibiotic course and a new AICD was placed.

In vitro Post-Antifungal Effect of Posaconazole and Its Impact on Adhesion-Related Traits and Hemolysin Production of Oral Candida dubliniensis Isolates

OBJECTIVE

Candidal adherence to denture acrylic surfaces (DAS) and oral buccal epithelial cells (BEC), formation of candidal germ tubes (GT), candidal cell surface hydrophobicity (CSH), and hemolysin production are important pathogenic traits of Candida. The antifungal drug-induced post-antifungal effect (PAFE) also impacts the virulence of Candida. Candida dubliniensis isolates are associated with the causation of oral candidiasis which could be managed with posaconazole. Thus far there is no evidence on posaconazole-induced PAFE and its impact on adhesion-related attributes and production of hemolysin by C. dubliniensis isolates. Hence, the PAFE, adhesion to DAS and BEC, formation of GT, CSH, and hemolysin production of 20 oral C. dubliniensis isolates after brief exposure to posaconazole was ascertained.

MATERIALS AND METHODS

The PAFE, adherence to DAS and BEC, formation of GT, candidal CSH, and hemolysin production were investigated by hitherto described in vitro assays.

RESULTS

The mean PAFE (h) induced by posaconazole on C. dubliniensis isolates was 1.66. Exposure to posaconazole suppressed the ability of C. dubliniensis to adhere to DAS, BEC, formation of candidal GT, candidal CSH and to produce hemolysin by a reduction of 44, 33, 34, 36, and 15% (p < 0.005 to p < 0.001), respectively.

CONCLUSION

Exposure of C. dubliniensis isolates to posaconazole for a brief period induced an antimycotic impact by subduing its growth in addition to suppressing pathogenic adherence-associated attributes, as well as production of hemolysin.

Candida dubliniensis abscess: A clinical case and a review of the literature

Candida dubliniensis infections are rare in the absence of prolonged immunocompromised status or intravenous drug abuse. We present a case of a C. dubliniensis soft tissue abscess in a patient with uncontrolled diabetes as his only immunocompromising risk factor, treated with surgical drainage and medical management.

Impact of Brief Exposure to Drugs with Antifungal Properties on the Susceptibility of Oral Candida dubliniensis Isolates to Lysozyme and Lactoferrin

OBJECTIVE

Lysozyme and lactoferrin have anti-candidal activity. Candida dubliniensis is associated with oral candidiasis. Candida infections are managed with nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole, and chlorhexidine. Candida species undergo a brief exposure to therapeutic agents in the mouth. There is no data on the influence of limited exposure to antimycotics on the sensitivity of C. dubliniensis to lactoferrin and lysozyme. Hence, this study observed the changes in the sensitivity of C. dubliniensis to anti-candidal action of lactoferrin and lysozyme after transitory exposure to sub-lethal concentrations of antifungals.

MATERIALS AND METHODS

After determination of the minimum inhibitory concentration (MIC), 20 C. dubliniensis isolates were exposed to twice the concentration of MIC of nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole, and chlorhexidine for 1 h. Drugs were removed by dilution and thereafter the susceptibility of these isolates to lysozyme and lactoferrin was determined by colony-forming unit quantification assay.

RESULTS

Exposure of C. dubliniensis to nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole, and chlorhexidine resulted in an increase in susceptibility to lysozyme by 9.45, 30.82, 30.04, 50.64, 55.60, and 50.18%, respectively (p < 0.05 to p < 0.001). Exposure of C. dubliniensis to nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole, and chlorhexidine resulted in an increase in susceptibility to lactoferrin by 13.54, 16.43, 17.58, 19.60, 21.32, and 18.73, respectively (p < 0.05 to p < 0.001).

CONCLUSION

Brief exposure to nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole, and chlorhexidine enhances the antifungal effect of lysozyme and lactoferrin on C. dubliniensis isolates in vitro.

Impact of short-term exposure of antifungal agents on hemolysin activity of oral Candida dubliniensis isolates from Kuwait and Sri Lanka

OBJECTIVE

Ability to produce hemolysin by Candida species is an important determinant of its pathogenicity. Candida dubliniensis is implicated in the causation of oral candidosis, which can be treated with polyene, echinocandin, and azole groups of antifungal agents as well as chlorhexidine. After oral application, however, the concentrations of these agents tend to decrease quickly to subtherapeutic levels due to the peculiarity of the oral environment. In this study, we have evaluated the effect of short-term exposure of sublethal concentrations of these drugs on hemolysin production by oral C. dubliniensis isolates obtained from two different geographical locale.

MATERIALS AND METHODS

Twenty C. dubliniensis oral isolates obtained from Kuwait and Sri Lanka were exposed to sublethal concentrations of nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole, and chlorhexidine for 1 h. Thereafter, the drugs were removed by dilution and the hemolysin production determined by a previously described plate assay.

RESULTS

Hemolysin production of these isolates was significantly suppressed with a percentage reduction of 17.09, 16.45, 17.09, 11.39, 8.23 and 12.03 following exposure to nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole, and chlorhexidine, respectively.

CONCLUSION

Brief exposure to sublethal concentrations of drugs with antifungal properties appears to reduce the pathogenic potential of C. dubliniensis isolates by suppressing hemolysin production.

Caspofungin-induced in-vitro post-antifungal effect and its impact on adhesion related traits of oral Candida dubliniensis and Candida albicans isolates

Adhesion to buccal epithelial cells (BEC) and denture acrylic surfaces (DAS), germ tube (GT) formation and cell surface hydrophobicity (CSH) are all virulence traits involved in the pathogenicity of Candida. Post-antifungal effect (PAFE) also have a bearing on pathogenicity and virulence of Candida. Candida dubliniensis is associated with oral and systemic candidosis, which can be managed with caspofungin. There is no published information on caspofungin-induced PAFE and its impact on adhesion traits of C. dubliniensis isolates. Thus, the purpose of this investigation was to determine the in vitro duration of PAFE on 20 C. dubliniensis isolates following transient exposure to caspofungin. Furthermore the impacts of caspofungin-induced PAFE on adhesion to BEC and DAS, GT formation and CSH of these isolates were also determined. After establishing the minimum inhibitory concentration (MIC) of caspofungin, C. dubliniensis isolates were exposed to sub-lethal concentrations (×3 MIC) of caspofungin for 1 hr. Thereafter the duration of PAFE, adhesion to BEC and DAS, GT formation and CSH were determined by previously described in-vitro assays. MIC (μg/mL) of C. dubliniensis isolates to caspofungin ranged from 0.004 to 0.19. Caspofungin-induced mean PAFE on C. dubliniensis isolates was 2.17 hr. Exposure to caspofungin suppressed the ability of C. dubliniensis isolates to adhere to BEC and DAS, form GT and CSH by 69.97%, 71.95%, 90.06% and 32.29% (P < 0.001 for all), respectively. Thus, transient exposure of C. dubliniensis isolates to caspofungin produces an antifungal effect not only by suppressing its growth but also by altering its adhesion traits.

In vitro postantifungal effect, adhesion traits and haemolysin production of Candida dubliniensis isolates following exposure to 5-fluorocytosine

The phenomenon of postantifungal effect (PAFE), which is the suppression of candidal growth following brief exposure to antifungal agents, is linked with candidal pathogenicity. Adhesion to buccal epithelial cells (BEC), germ tube (GT) formation and relative cell surface hydrophobicity (CSH) are all adhesion traits of candidal pathogenicity. Ability to produce haemolysin by Candida species is also a determinant of its pathogenicity. There is no information on either the PAFE or its impact on adhesion traits and haemolysin production of oral Candida dubliniensis isolates following exposure to 5-fluorocytosine (5-FC). Hence, the focus of this investigation was to research the in vitro PAFE, adhesion to BEC, GT formation, relative CSH and haemolysin production on 20 C. dubliniensis isolates following exposure to 5-FC. Following obtaining the minimum inhibitory concentration (MIC) of 5-FC, isolates of C. dubliniensis were exposed to sub-lethal concentrations (×3 MIC) of 5-FC for 1 h. After this brief exposure, the antimycotic was removed and PAFE, adhesion to BEC, GT formation, relative CSH and haemolysin production was determined by formerly described in vitro methods. MIC (μg/ml) of C. dubliniensis isolates to 5-FC ranged from 0.002 to 0.125. The mean PAFE (hours) elicited by 5-FC on C. dubliniensis isolates was approximately 1 h. Exposure to 5-FC suppressed the ability of C. dubliniensis isolates to adhere BEC, GT formation, relative CSH and haemolysin activity by a mean percentage reduction in 50.98%, 29.51%, 36.79% and 12.75% (P < 0.001 for all) respectively. Therefore, brief exposure of C. dubliniensis isolates to 5-FC appears to exert an antifungal effect by subduing its growth, adhesion traits as well as haemolysin production.

In vitro adhesion of oral Candida dubliniensis isolates to acrylic denture surfaces following brief exposure to sub-cidal concentrations of polyenes, azoles and chlorhexidine

OBJECTIVES

We aimed to investigate the effect of brief exposure to sub-cidal concentrations of nystatin, amphotericin B, ketoconazole, fluconazole and chlorhexidine gluconate on the adhesion of oral Candida dubliniensis isolates to the surface of acrylic dentures.

METHODS

After determining the minimum inhibitory concentration of each drug, 20 oral isolates of C. dubliniensis were exposed to sub-cidal concentrations of the drugs for 1 h. The drugs were then removed by dilution, and the adhesion of the isolates to denture acrylic strips was assessed by an in vitro adhesion assay.

RESULTS

Compared to the controls, exposure to nystatin, amphotericin B, ketoconazole, fluconazole and chlorhexidine gluconate suppressed the ability of C. dubliniensis isolates to adhere to acrylic denture surfaces with a reduction of 74.68, 74.27, 57.31, 44.57 and 56.53% (p < 0.001 for all drugs), respectively.

CONCLUSIONS

Brief exposure to sub-cidal concentrations of anti-mycotics suppressed the adhesion of C. dubliniensis oral isolates to acrylic denture surfaces.

Impact of brief and sequential exposure to nystatin, amphotericin B, ketoconazole, and fluconazole in modulating adhesion traits of oral Candida dubliniensis isolates

AIM

Candida adherence is implicated in the pathogenesis of oral candidosis. Adhesion to buccal epithelial cells (BEC), germ tube (GT) formation, and relative cell surface hydrophobicity (CSH) are colonization attributes of candidal pathogenicity. Candida dubliniensis (C. dubliniensis) is allied with recurrent oral candidosis, which can be treated with nystatin, amphotericin B, ketoconazole, and fluconazole. Due to the diluent effect of saliva and the cleansing effect of the oral musculature in the oral cavity C. dubliniensis isolates undergo brief and sequential exposure to antifungal agents during therapy. Thus, in the present study, we evaluated the adhesion to BEC, GT formation, and the CSH of oral isolates of C. dubliniensis following brief and sequential exposure to nystatin, amphotericin B, ketoconazole, and fluconazole.

METHODS

After determining the minimum inhibitory concentration (MIC) of the aforementioned drugs, 20 oral isolates of C. dubliniensis were briefly (1 h), and sequentially (10 days) exposed to subcidal concentrations of these drugs. Following drug removal, adhesion to BEC, GT formation, and CSH of these isolates were determined.

RESULTS

The percentage reduction of adhesion to BEC, GT formation, and CSH of the isolates following exposure to antifungal agents were as follows: nystatin: 53.55%, 33.98%, and 29.83% (P < 0.001); amphotericin B: 53.84%, 36.23%, and 28.97% (P < 0.001); ketoconazole: 37.43%, 20.51%, and 16.49% (P < 0.001); and fluconazole: 8.93% (P < 0.001), 1.6%, and 0.63% (P > 0.05).

CONCLUSIONS

Brief and sequential exposure of C. dubliniensis to antifungal agents would continue to wield an antifungal effect by altering its adhesion attributes, and elucidate possible pharmacodynamics by which antifungal agents might operate in modulating candidal adherence.

Post-antifungal effect and adhesion to buccal epithelial cells of oral Candida dubliniensis isolates subsequent to limited exposure to amphotericin B, ketoconazole and fluconazole

AIM

The post-antifungal effect (PAFE) of Candida and its adherence to oral mucosal surfaces are important determinants of candidal pathogenicity. Candida dubliniensis is allied with recurrent oral candidosis. Oral candidosis can be treated with amphotericin B, ketoconazole and fluconazole. There is no information on the PAFE and its impact on adhesion to oral buccal epithelial cells (BEC) of oral C. dubliniensis isolates. Therefore, the main objective was to reconnoiter the PAFE and adhesion to BEC of 20 C. dubliniensis isolates following brief exposure to aforementioned antimycotics.

METHODS

After determining the minimum inhibitory concentration (MIC), C. dubliniensis isolates were exposed to sub-lethal concentrations of these drugs for 1 h. Following subsequent drug removal, the PAFE and adhesion to BEC, was determined by a turbidometric method, and an adhesion assay, respectively.

RESULTS

Minimum inhibitory concentration (μg/mL) to amphotericin B, ketoconazole and fluconazole, ranged from 0.002 to 0.125, 0.002 to 0.012 and 0.016 to 0.38, respectively. Amphotericin B and ketoconazole induced mean PAFE (hours) were 2.21 and 0.6, respectively. Fluconazole failed to produce a detectable PAFE. Compared to controls, amphotericin B, ketoconazole and fluconazole suppressed the ability to adhere to BEC with a mean percentage reduction of 74.31%, 49.80% (P < 0.0001) and 29.36% (P < 0.05), respectively.

CONCLUSIONS

Brief exposure to sub-lethal concentrations of aforementioned drugs would exert an antifungal effect by modifying the growth and adhesion of C. dubliniensis isolates.

Candida dubliniensis endophthalmitis: five cases over 15 years

Background

Recent studies have shown that the recently identified organism Candida dubliniensis is less pathogenic than the more common Candida albicans. Due to its rare nature, C. dubliniensis has been previously reported as the causative organism in endophthalmitis in only three cases. We undertook a multicenter, retrospective, consecutive case series to describe the clinical features and outcomes of patients with culture-proven C. dubliniensis endophthalmitis. Medical records were reviewed for all patients with C. dubliniensis endophthalmitis on vitreous/aqueous cultures from June 1998 to June 2013 from all public hospitals throughout Queensland, Australia.

Results

Six eyes from five patients were identified - four males and one female aged from 21 to 55 years (mean 37 years). Four patients were intravenous drug users and four patients had hepatitis C. All five patients were treated with systemic antifungal therapy and intravitreal antifungal injections, and all required vitrectomy. Two eyes developed retinal detachment over the course of the endophthalmitis. Five eyes had visual outcomes of 20/60 or better, and one eye had a poor outcome with final visual acuity of hand movements only. There was no associated mortality, and no infected eyes required enucleation or evisceration.

Conclusions

C. dubliniensis endophthalmitis is a rare condition which occurs mainly in intravenous drug users and can occur in both HIV-positive and HIV-negative patients. Unlike C. albicans endophthalmitis, C. dubliniensis endophthalmitis has reasonable visual outcomes and does not appear to be associated with high mortality.

The postantifungal effect of nystatin and its impact on adhesion attributes of oral Candida dubliniensis isolates

The postantifungal effect (PAFE) has an impact on candidal pathogenicity. However, there is no information on either the PAFE or its impact on adhesion traits of oral Candida dubliniensis isolates. Oral candidosis can be treated topically with nystatin. Adhesion to buccal epithelial cells (BEC), germ tube (GT) formation and relative cell surface hydrophobicity (CSH) are all colonisation attributes of candidal pathogenicity. Hence, the main objective of this study was to investigate the in vitro PAFE on 20 C. dubliniensis isolates following exposure to nystatin. In addition, the impact of nystatin-induced PAFE on adhesion to BEC, GT formation and relative CSH of C. dubliniensis isolates were also evaluated. After determining the minimum inhibitory concentration (MIC) of nystatin, C. dubliniensis isolates were exposed to sublethal concentrations of nystatin for 1 h. Following this exposure, the drug was removed and PAFE, adhesion to BEC, GT formation and relative CSH were determined by a previously described turbidometric method, adhesion assay, germ tube induction assay and biphasic aqueous-hydrocarbon assay respectively. MIC (μg/ml) of C. dubliniensis isolates to nystatin ranged from 0.09 to 0.78. The nystatin-induced mean PAFE (hours) on C. dubliniensis isolates was 2.17. Compared with the controls, exposure to nystatin suppressed the ability of C. dubliniensis isolates to adhere BEC, GT formation and relative CSH by a mean percentage reduction of 74.45% (P < 0.0001), 95.92% (P < 0.0001) and 34.81 (P < 0.05) respectively. Hence, brief exposure of C. dubliniensis isolates to nystatin would continue to wield an antifungal effect by suppressing growth as well as its adhesion attributes.

Catheter-related fungemia caused by Candida dubliniensis

Infections caused by Candida dubliniensis in humans are rare and have never been reported in Taiwan. We report two cancer patients with catheter-related fungemia due to C. dubliniensis infection in Taiwan. The two isolates were confirmed to the species level using an oligonucleotide array system and sequence analysis, and both showed high in vitro susceptibilities to nine antifungal agents. The catheters were removed, and both patients responded well to antifungal treatment. Although this type of infection is rare, physicians should consider C. dubliniensis as one of the possible pathogens causing catheter-related infections in Taiwan.

The first Korean case of candidemia due to Candida dubliniensis

Candidemia due to uncommon Candida spp. appears to be increasing in incidence. C. dubliniensis has been increasingly recovered from individuals not infected with HIV. Identification of C. dubliniensis can be problematic in routine clinical practice due to its phenotypic resemblance to C. albicans. We report the first case of C. dubliniensis candidemia in Korea, which occurred in a 64-yr-old woman who presented with partial seizure, drowsiness, and recurrent fever. Germ-tube positive yeast that was isolated from blood and central venous catheter tip cultures formed smooth, white colonies on sheep blood agar and Sabouraud agar plates, indicative of Candida spp. C. dubliniensis was identified using the Vitek 2 system (bioMerieux, USA), latex agglutination, chromogenic agar, and multiplex PCR. The blood isolate was susceptible to flucytosine, fluconazole, voriconazole, and amphotericin B. After removal of the central venous catheter and initiation of fluconazole treatment, the patient's condition gradually improved, and she was cleared for discharge from our hospital. Both clinicians and microbiologists should be aware of predisposing factors to C. dubliniensis candidemia in order to promote early diagnosis and appropriate treatment.

Cell surface hydrophobicity of oral Candida dubliniensis isolates following limited exposure to sub-therapeutic concentrations of chlorhexidine gluconate

Candidal adhesion has been implicated as the initial step in the pathogenesis of oral candidiasis and cell surface hydrophobicity (CSH) has been implicated in adhesion to mucosal surfaces. Candida dubliniensis is an opportunistic pathogen associated with recurrent oral candidiasis. Chlorhexidine gluconate is by far the commonest antiseptic mouth wash prescribed in dentistry. At dosage intervals the intraoral concentration of this antiseptic fluctuates considerably and reaches sub-therapeutic levels due to the dynamics of the oral cavity. Hence, the organisms undergo only a limited exposure to the antiseptic during treatment. The impact of this antiseptic following such exposure on CSH of C. dubliniensis isolates has not been investigated. Hence, the main objective of this study was to investigate the effect of brief exposure to sub-therapeutic concentrations of chlorhexidine gluconate on the CSH of C. dubliniensis isolates. Twelve oral isolates of C. dubliniensis were briefly exposed to three sub-therapeutic concentrations of 0.005%, 0.0025% and 0.00125% chlorhexidine gluconate for 30 min. Following subsequent removal of the drug, the CSH of the isolates was determined by a biphasic aqueous-hydrocarbon assay. Compared with the controls, exposure to 0.005% and 0.0025% chlorhexidine gluconate suppressed the relative CSH of the total sample tested by 44.49% (P < 0.001) and 21.82% (P < 0.018), respectively, with all isolates being significantly affected. Although exposure to 0.00125% of chlorhexidine gluconate did not elicit a significant suppression on the total sample tested (7.01%; P > 0.05), four isolates of the group were significantly affected. These findings imply that exposure to sub-therapeutic concentrations of chlorhexidine gluconate may suppress CSH of C. dublinienis isolates, thereby reducing its pathogenicity and highlights further the pharmacodynamics of chlorhexidine gluconate.

Candida dubliniensis: an appraisal of its clinical significance as a bloodstream pathogen

A nine-year prospective study (2002–2010) on the prevalence of Candida dubliniensis among Candida bloodstream isolates is presented. The germ tube positive isolates were provisionally identified as C. dubliniensis by presence of fringed and rough colonies on sunflower seed agar. Subsequently, their identity was confirmed by Vitek2 Yeast identification system and/or by amplification and sequencing of the ITS region of rDNA. In all, 368 isolates were identified as C. dubliniensis; 67.1% came from respiratory specimens, 11.7% from oral swabs, 9.2% from urine, 3.8% from blood, 2.7% from vaginal swabs and 5.4% from other sources. All C. dubliniensis isolates tested by Etest were susceptible to voriconazole and amphotericin B. Resistance to fluconazole (≥8 µg/ml) was observed in 2.5% of C. dubliniensis isolates, 7 of which occurred between 2008–2010. Of note was the diagnosis of C. dubliniensis candidemia in 14 patients, 11 of them occurring between 2008–2010. None of the bloodstream isolate was resistant to fluconazole, while a solitary isolate showed increased MIC to 5-flucytosine (>32 µg/ml) and belonged to genotype 4. A review of literature since 1999 revealed 28 additional cases of C. dubliniensis candidemia, and 167 isolates identified from blood cultures since 1982. In conclusion, this study highlights a greater role of C. dubliniensis in bloodstream infections than hitherto recognized.

Candida dubliniensis endophthalmitis: first case in North America

To report an unusual case of endogenous fungal endophthalmitis due to Candida dubliniensis. Interventional case report of a 27-year-old immunocompetent male with loss of vision, dense vitritis, and chorioretinal infiltrates, who underwent a diagnostic pars plana vitrectomy. Microbiology cultures obtained by a diagnostic vitrectomy were positive for the growth of C. dubliniensis. This infectious process was then appropriately treated with intravitreal amphotericin B and systemic fluconazole with resolution of the endophthalmitis. Endogenous fungal endophthalmitis is a condition that can masquerade other more common causes of endophthalmitis. Atypical cases of endophthalmitis may benefit from diagnostic pars plana vitrectomy for prompt diagnosis and treatment.

Presence of Candida spp. in the oral cavity of heart transplantation patients

Candida spp. can lead to infections or even fungal sepsis particularly among immunocompromized individuals.

The first documented case of Candida dubliniensis leptomeningeal disease in an immunocompetent host

In June 2008, a 25-year-old man presented to the Royal Adelaide Hospital, Australia, with Candida dubliniensis leptomeningeal disease. On examination the patient had focal neurological deficits, both sensory and motor. He tested negative for HIV and had normal T cell subsets. The patient was treated with 6 weeks of intravenous liposomal amphotericin B and oral flucytosine, and had a full recovery.

Calcineurin controls drug tolerance, hyphal growth, and virulence in Candida dubliniensis

Candida dubliniensis is an emerging pathogenic yeast species closely related to Candida albicans and frequently found colonizing or infecting the oral cavities of HIV/AIDS patients. Drug resistance during C. dubliniensis infection is common and constitutes a significant therapeutic challenge. The calcineurin inhibitor FK506 exhibits synergistic fungicidal activity with azoles or echinocandins in the fungal pathogens C. albicans, Cryptococcus neoformans, and Aspergillus fumigatus. In this study, we show that calcineurin is required for cell wall integrity and wild-type tolerance of C. dubliniensis to azoles and echinocandins; hence, these drugs are candidates for combination therapy with calcineurin inhibitors. In contrast to C. albicans, in which the roles of calcineurin and Crz1 in hyphal growth are unclear, here we show that calcineurin and Crz1 play a clearly demonstrable role in hyphal growth in response to nutrient limitation in C. dubliniensis. We further demonstrate that thigmotropism is controlled by Crz1, but not calcineurin, in C. dubliniensis. Similar to C. albicans, C. dubliniensis calcineurin enhances survival in serum. C. dubliniensis calcineurin and crz1/crz1 mutants exhibit attenuated virulence in a murine systemic infection model, likely attributable to defects in cell wall integrity, hyphal growth, and serum survival. Furthermore, we show that C. dubliniensis calcineurin mutants are unable to establish murine ocular infection or form biofilms in a rat denture model. That calcineurin is required for drug tolerance and virulence makes fungus-specific calcineurin inhibitors attractive candidates for combination therapy with azoles or echinocandins against emerging C. dubliniensis infections.

A comparison of the antifungal activity of herbal toothpastes against other brands of toothpastes on clinical isolates of Candida albicans and Candida dubliniensis

OBJECTIVES

To evaluate the anti-Candida activity on Candida albicans and Candida dubliniensis species of 2 herbal and 7 other brands of toothpastes commonly used in Kuwait.

MATERIALS AND METHODS

Antifungal activity was determined by agar diffusion test on 65 isolates of C. albicans and 21 isolates of C. dubliniensis for each toothpaste. A uniform quantity of toothpaste was filled into wells punched into Sabouraud dextrose agar medium plates inoculated with the test isolates, incubated at 37°C; inhibition zone diameters were read after 24 h.

RESULTS

The mean inhibition zone diameters ranged between 12 and 23 mm for C. albicans and between 12 and 27 mm for C. dubliniensis. A herbal toothpaste brand manufactured in the Middle Eastern region (United Arab Emirates) consisting of many herbal ingredients compared to other brands was found to be the most active (p < 0.001) against both Candida species tested, which also demonstrated higher inhibitory activity against C. dubliniensis isolates compared to C. albicans.

CONCLUSIONS

The herbal toothpaste brand presented significant anticandidal activity over conventional toothpastes and may be useful in reducing the pathogenic potential of Candida species.

Prevalence of Candida dubliniensis among cancer patients in Kuwait: a 5-year retrospective study

Despite close genetic and phenotypic relationship of Candida dubliniensis with Candida albicans, its role in human disease is mostly restricted to oral colonisation, particularly among HIV-infected patients. The prevalence of C. dubliniensis in association with other disease conditions has been infrequently reported. In this study, we present data on the prevalence of C. dubliniensis among yeast species isolated from cancer patients over a 5-year period. A total of 1445 yeast isolates recovered from respiratory specimens, blood, urine and oral swabs were analysed. Candida dubliniensis isolates were provisionally identified by phenotypic methods and their identity was further confirmed by species-specific amplification and/or sequencing of internally transcribed spacer region of rDNA. Antifungal susceptibility for fluconazole was determined by Etest. The number of isolates identified as C. dubliniensis, C. albicans and other yeast species were 71 (4.9%), 862 (59.6%) and 512 (35%) respectively. All the C. dubliniensis isolates originated from respiratory (5.9%) or oral (3.2%) specimens with an overall prevalence of 4.9%, and were found to be susceptible to fluconazole. The isolation of C. dubliniensis from respiratory or oral specimens and not from blood or urine specimens suggests that this species has preference to colonise these sites of human body.

Multifocal osteomyelitis caused by Candida dubliniensis

Candida dubliniensis is an emerging fungal pathogen, especially in immunodeficient patients. We report what is to the best of our knowledge the first case of multifocal osteomyelitis following disseminated infection in a patient after haematopoietic stem cell transplantation. PFGE for typing of C. dubliniensis was developed and the necessity of long-term antifungal therapy is discussed.

Candida dubliniensis meningitis as delayed sequela of treated C. dubliniensis fungemia

We present a case of Candida dubliniensis meningitis that developed 2 months after apparently successful treatment of an episode of C. dubliniensis candidemia in a heart-lung transplant recipient in Australia. This case highlights the importance of follow-up in patients with candidemia or disseminated infection, especially in immunosuppressed patients.

[An update on Candida dubliniensis]

Eleven years ago, Irish authors, using molecular biology, demonstrated the existence of Candida dubliniensis, a new species of Candida close to Candida albicans. Initially isolated from AIDS patients with oral candidiasis, this species was detected, even in immunocompetent patients. Recently, with new, easy to implement identification tests (latex, immunochromatography), numerous epidemiological studies were undertaken. In most studies, C. dubliniensis was most often identified in the oral cavity. In the absence of HIV infection, the proportion C. dubliniensis/C. albicans ranged from 1 to 5% but it increased to 15-20% in case of HIV infection. It should be stressed that, from an experimental point of view, the acquisition of a secondary resistance to fluconazole is more quickly obtained with C. dubliniensis that with C. albicans, this resistance remains exceptionally observed in clinical observations.

Candida dubliniensis isolated from the sputum of a patient with end-stage liver cirrhosis

Candida dubliniensis is rare and very similar to C. albicans. To date, detailed clinical reports on C. dubuliniensis recovered from an immunocompromised patient have not been described in Japan. A 71-year-old man with end-stage liver cirrhosis had been treated for suppurative omarthritis due to methicillin-resistant Staphylococcus aureus (MRSA). Anti-MRSA agents and broad-spectrum antimicrobials but no antifungal agents had been administrated. C. dubliniensis, isolated from the sputum, was eliminated by selective digestive decontamination and supportive therapy. This case emphasizes the need to recognize this emerging Candida sp., C. dubliniensis in cases of opportunistic infection.

Evolution of antibody response and fungal antigens in the serum of a patient infected with Candida famata

The presence of fungal antibodies and antigens in the serum of a patient diagnosed in 1996 with acute zonal occult outer retinopathy caused by Candida famata infection was examined. Antibodies against C. famata increased until 1999–2000 when antifungal treatment was initiated. The antibodies were detected by ELISA and immunofluorescence analysis using C. famata. These antibodies were not immunoreactive against several Candida species tested. Positive immunofluorescence was obtained with IgM, but not IgA, IgG or IgE. Moreover, the IgM response disappeared several months after treatment with antifungal compounds, despite the fact that C. famata antigens were present in the blood. Finally, a sensitive test was developed to assay for the presence of C. famata antigens in serum based on the immunodetection of fungal antigens transferred to a nitrocellulose membrane and incubated with rabbit antibodies raised against C. famata. According to this method, the infection diminished with antifungal treatment.

Effect of farnesol onCandida dubliniensisbiofilm formation and fluconazole resistance

Candida dubliniensis and Candida albicans are dimorphic fungal species with a number of pathogenic capabilities, including biofilm formation, systemic infection and development of fluconazole resistance. In this study, the ability of farnesol to disrupt these virulence capabilities was investigated. Biofilm assessment and susceptibility studies indicated antifungal and antibiofilm properties for farnesol on both species with a disruptive effect on the cell membrane. Synergy testing of farnesol and fluconazole in resistant strains resulted in reversal of fluconazole resistance, indicating a potential application for farnesol as an adjuvant therapeutic agent.

Species Distribution and Antifungal Susceptibility Profile of Oral Candida Isolates from HIV-infected Patients in the Antiretroviral Therapy Era

In this study, we investigated the yeasts colonization of genus Candida, including C. dubliniensis, isolated of HIV-infected patients oral cavities and we accessed in vitro susceptibility pattern of the Candida isolates to four antifungal agents. Out of 99 patients investigated, 62 (62.6%) were colonized with yeasts. C. albicans was the prevailing species (50%). C. dubliniensis isolates were not recovered in our study. We verified that 8.1% of the yeasts isolated were resistant to fluconazole, 8.1% to itraconazole and 3.2% to voriconazole. The isolates demonstrated very low voriconazole MICs, in which 79% (49/62) presented values of 0.015 mug/ml. All Candida isolates were susceptible to amphotericin B. The results reported here showed that although C. albicans continues to be present in one-half of oral Candida carriage of HIV-infected patients, Candida non-albicans species are increasing among these patients. Besides, the findings of resistant isolates endorse the role of antifungal susceptibility testing whenever antifungal treatment with azoles is planned.

Evaluation of 5 new media containing extracts of seeds applied to Candida dubliniensis screening

Candida dubliniensis is a recently described pathogenic species that shares many phenotypic features with Candida albicans and so may be misidentified in microbiologic laboratories. The aim of this study is to find a useful and cost-effective method suitable for screening C. dubliniensis before proceeding to further identification. We examined the colony morphology and chlamydospore production of 26 C. dubliniensis isolates and 100 C. albicans isolates on the following 5 proposed media: sesame seed agar (SSA), rapeseed agar, canary grass seed agar, millet seed agar, and linseed agar (LA). The best results were obtained with SSA and LA because all 26 C. dubliniensis isolates showed rough colonies with peripheral hyphal fringes and abundant chlamydospores after 24 to 48 h of incubation at 25 degrees C. All C. albicans isolates (100%) showed smooth colonies without hyphal fringes or chlamydospores. These 2 media consist of new and simple tools for presumptive differentiation of C. dubliniensis from C. albicans.

Evaluation of amphotericin B interpretive breakpoints for Candida bloodstream isolates by correlation with therapeutic outcome

One hundred seven Candida bloodstream isolates (51 C. albicans, 24 C. glabrata, 13 C. parapsilosis, 13 C. tropicalis, 2 C. dubliniensis, 2 C. krusei, and 2 C. lusitaniae strains) from patients treated with amphotericin B alone underwent in vitro susceptibility testing against amphotericin B using five different methods. Fifty-four isolates were from patients who failed treatment, defined as death 7 to 14 days after the incident candidemia episode, having persistent fever of >or=5 days' duration after the date of the incident candidemia, or the recurrence of fever after two consecutive afebrile days while on antifungal treatment. MICs were determined by using the Clinical Laboratory Standards Institute (formally National Committee for Clinical Laboratory Standards) broth microdilution procedure with two media and by using Etest. Minimum fungicidal concentrations (MFCs) were also measured in two media. Broth microdilution tests with RPMI 1640 medium generated a restricted range of MICs (0.125 to 1 microg/ml); the corresponding MFC values ranged from 0.5 to 4 microg/ml. Broth microdilution tests with antibiotic medium 3 produced a broader distribution of MIC and MFC results (0.015 to 0.25 microg/ml and 0.06 to 2 microg/ml, respectively). Etest produced the widest distribution of MICs (0.094 to 2 microg/ml). However, none of the test formats studied generated results that significantly correlated with therapeutic success or failure.

In vitro activities of new and conventional antimycotics against fluconazole-susceptible and non-susceptible Brazilian Candida spp. isolates

The substantial increase in the rate of azole resistant Candida spp. yeast infections has become a serious treatment problem requiring new and more active antifungal agents. In this study, the in vitro activities of ravuconazole and albaconazole were compared with those of amphotericin B, flucytosine, itraconazole and fluconazole against 162 Brazilian isolates of Candida spp. from which 48 isolates had previously shown lower susceptibility or resistance to fluconazole. Ravuconazole susceptibility ranged from 84.6% (Candida albicans) to 100% for other species and albaconazole MIC(90) was < or =1.0 microg ml(-1) for all the species emphasising the potent activity of these triazoles. To our knowledge this is the first study evaluating the susceptibility of C. dubliniensis to albaconazole.

Molecular identification of Candida dubliniensis isolated from oral lesions of HIV-positive and HIV-negative patients in São Paulo, Brazil

Candida dubliniensis is a new, recently described species of yeast. This emerging oral pathogen shares many phenotypic and biochemical characteristics with C. albicans, making it hard to differentiate between them, although they are genotypically distinct. In this study, PCR (Polymerase Chain Reaction) was used to investigate the presence of C. dubliniensis in samples in a culture collection, which had been isolated from HIV-positive and HIV-negative patients with oral erythematous candidiasis. From a total of 37 samples previously identified as C. albicans by the classical method, two samples of C. dubliniensis (5.4%) were found through the use of PCR. This study underscores the presence of C. dubliniensis, whose geographical and epidemiological distribution should be more fully investigated.

Initial Candida dubliniensis isolate in Candida spp. positive haemocultures in Turkey between 2001 and 2004

Candida dubliniensis which was first recognized in 1995 can be easily misidentified because of its phenotypic similarities with Candida albicans. In this study blood samples of patients from various departments of Ankara University Medical Faculty between January 2001-June 2004 were investigated for the distribution of Candida spp. and the presence of C. dubliniensis. Culture positive 67 fungi were included to the study. Phenotypic tests such as chlamydospore formation, colony morphology on Staib agar, growth at 45 degrees C, carbohydrate assimilation profiles were investigated for identification and differentiation of C. dubliniensis from C. albicans. To confirm the results polymerase chain reaction were used for suspected C. albicans and C. dubliniensis isolates. Among 38 germ tube and chlamydospore forming isolates, 37 of them were found as C. albicans and one as C. dubliniensis. The incidence of C. dubliniensis in our hospital is still low, this is the first C. dubliniensis isolate as an agent of candidaemia reported from Turkey.

Azole susceptibility and resistance in Candida dubliniensis

Candida dubliniensis is a recently described species of pathogenic yeast that shares many phenotypic features with Candida albicans. It is primarily associated with oral colonization and infection in HIV-infected individuals. Isolates of C. dubliniensis are generally susceptible to commonly used azole antifungal agents; however, resistance has been observed in clinical isolates and can be induced by in vitro exposure. Molecular mechanisms of azole resistance in C. dubliniensis include increased drug efflux, modifications of the target enzyme and alterations in the ergosterol biosynthetic pathway.

Novel 5-flucytosine-resistant clade of Candida dubliniensis from Saudi Arabia and Egypt identified by Cd25 fingerprinting

DNA fingerprinting of Candida dubliniensis isolates using the species-specific probe Cd25 previously showed that this species consists of two distinct groups, termed Cd25 group I and Cd25 group II. The present study investigated the population structure of 30 C. dubliniensis oral isolates from Saudi Arabia and Egypt using Cd25 fingerprinting and rRNA gene internal transcribed spacer region-based genotyping. Cd25 fingerprinting analysis of these isolates revealed two distinct populations, the first of which consisted of 10 closely related genotype 1 isolates (average similarity coefficient [S(AB)] value, 0.86). The second population of 20 isolates was much more heterogeneous (average S(AB) value, 0.35) and consisted of two distinct subpopulations, one of which consisted of genotype 3 isolates (n = 13) and the other of genotype 4 isolates (n = 7). A mixed dendrogram generated from the fingerprint data from the 30 Saudi Arabian and Egyptian isolates, 5 Israeli isolates, and 51 previously characterized international isolates (32 of Cd25 group I and 19 of Cd25 group II) revealed the presence of three distinct main clades. The first corresponded to the previously described Cd25 group I and contained all the Saudi Arabian, Egyptian, and Israeli genotype 1 isolates mixed with international isolates. The second clade corresponded to the previously described Cd25 group II and contained three Israeli isolates, one genotype 2 isolate, one genotype 3 isolate, and a genotype 4 variant isolate, which were mixed with international isolates. The third clade has not been described before and consisted solely of the 20 Saudi Arabian and Egyptian genotype 3 and 4 isolates identified in this study and a previously described genotype 4 Israeli isolate. All 20 Cd25 group III isolates exhibited high-level resistance to 5-flucytosine (MIC > or = 128 microg/ml), whereas all Cd25 group I and Cd25 group II isolates tested (10 Saudi Arabian and Egyptian, 16 Israeli, and 24 international) were susceptible to 5-flucytosine (MIC < or = 0.125 microg/ml). The results of this study show for the first time the presence of a novel 5-flucytosine-resistant clade of C. dubliniensis (Cd25 group III) that is predominant among isolates from Saudi Arabia and Egypt and absent from a previously characterized international collection of 98 isolates from 15 countries.

Detection of Candida dubliniensis in oropharyngeal samples from human immunodeficiency virus infected and non-infected patients and in a yeast culture collection

The incidence of Candida dubliniensis in oropharyngeal swabs of 132 human immunodeficiency virus (HIV)-positive and 89 HIV-negative patients was determined. The samples were plated onto CHROMagar Candida medium and 82 strains, presumptively identified as C. albicans or C. dubliniensis, were further investigated (temperature test, chlamydoconidia production, specific primer PCR). In addition, 487 collection strains (isolated from clinical samples and previously identified as C. albicans on the basis of a positive germ tube test) were screened in order to identify C. dubliniensis isolates. Two C. dubliniensis strains were isolated from two HIV-positive patients without oral candidiasis. Candida dubliniensis was not isolated from 89 HIV-negative patients nor was it identified among the collection strains.

Phenotypic and molecular characterization of Candida dubliniensis isolates from clinical specimens in Kuwait

OBJECTIVE

This study was carried out to characterize Candida dubliniensis using phenotypic and molecular methods and to determine the occurrence of C. dubliniensis in clinical specimens in Kuwait.

MATERIALS AND METHODS

A total of 880 clinical specimens for isolation of fungi were processed according to standard procedures. Of these, 390 germ-tube-positive clinical isolates of Candida species were examined for rough colonies with hyphal fringes and chlamydospore production on simplified sunflower seed agar for their presumptive phenotypicidentification as C. dubliniensis. The identification of C. dubliniensis isolates was further confirmed by the Vitek 2 yeast identification system, semi-nested (sn) PCR amplification of high-copy rDNA and direct DNA sequencing of the internally transcribed spacer 2 (ITS2) region.

RESULTS

Of the 390 isolates of Candida species investigated, 12 were identified as C. dubliniensis, giving an overall occurrence of 3%. All the C. dubliniensis isolates formed rough colonies with hyphal fringes and abundant chlamydospores on sunflower seed agar, did not assimilate trehalose, lactate and alpha-methyl-D-glucoside, and were isolated from human immunodeficiency virus (HIV)-negative patients. Four C. dubliniensis isolates utilized D-xylose. The species-specific primer derived from the ITS2 sequence of C. dubliniensis and used together with the panfungal reverse primer in the reamplification step of the snPCR specifically amplified rDNA from reference and clinical C. dubliniensis isolates and not from C. albicans or other Candida species. The identity of two representative isolates was confirmed by DNA sequencing of the ITS2 region.

CONCLUSIONS

The identity of 12 C. dubliniensis isolates was first established by phenotypic characteristics and then by snPCR using species-specific primers derived from ITS2 sequences. The recovery of C. dubliniensis from HIV-negative patients from Kuwait reinforces the existing view that this novel yeast species has a worldwide distribution and its occurrence is not restricted to any particular immunocompromised population.