Invasive infections due to Candida krusei: report of ten cases of fungemia that include three cases of endophthalmitis

Pichia kudriavzevii (Candida krusei): A systematic review to inform the World Health Organisation priority list of fungal pathogens

In response to the growing global threat of fungal infections, in 2020 the World Health Organisation (WHO) established an Expert Group to identify priority fungi and develop the first WHO fungal priority pathogen list (FPPL). The aim of this systematic review was to evaluate the features and global impact of invasive infections caused by Pichia kudriavzevii (formerly known as Candida krusei). PubMed and Web of Science were used to identify studies published between 1 January 2011 and 18 February 2021 reporting on the criteria of mortality, morbidity (defined as hospitalisation and length of stay), drug resistance, preventability, yearly incidence, and distribution/emergence. Overall, 33 studies were evaluated. Mortality rates of up to 67% in adults were reported. Despite the intrinsic resistance of P. kudriavzevii to fluconazole with decreased susceptibility to amphotericin B, resistance (or non-wild-type rate) to other azoles and echinocandins was low, ranging between 0 and 5%. Risk factors for developing P. kudriavzevii infections included low birth weight, prior use of antibiotics/antifungals, and an underlying diagnosis of gastrointestinal disease or cancer. The incidence of infections caused by P. kudriavzevii is generally low (∼5% of all Candida-like blood isolates) and stable over the 10-year timeframe, although additional surveillance data are needed. Strategies targeting the identified risk factors for developing P. kudriavzevii infections should be developed and tested for effectiveness and feasibility of implementation. Studies presenting data on epidemiology and susceptibility of P. kudriavzevii were scarce, especially in low- and middle-income countries (LMICs). Thus, global surveillance systems are required to monitor the incidence, susceptibility, and morbidity of P. kudriavzevii invasive infections to inform diagnosis and treatment. Timely species-level identification and susceptibility testing should be conducted to reduce the high mortality and limit the spread of P. kudriavzevii in healthcare facilities.

A Case of Central Venous Catheter-Related Candida parapsilosis Fungemia Evolved to Disseminated Infection in a Neutropenic Patient with Blast Crisis of Chronic Myeloid Leukemia

Central venous catheter-related infections are of particular importance in onco-hematological patients. Candida parapsilosis is generally reported as a mild pathogen, however it is able to effectively colonize intravascular devices and potentially give rise to sustained fungemias. Here we report a case of invasive, potentially lethal C. parapsilosis disseminated infection in a neutropenic patient affected by chronic myeloid leukemia with blast crisis. We underline the importance of removing the central venous catheter as potential source of infection as soon as possible during the course of candidemia, and not replacing it with other polyurethan intravascular devices, which pose a risk for the maintenance of the fungemia despite the administration of the best antifungal therapy available.

Quantification of Oral Candidal Carriage Rate and Prevalence of Oral Candidal Species in HIV Patients with and Without Highly Active Antiretroviral Therapy

BACKGROUND

Most documents review decrease in the prevalence of HIV related oral lesions to the tune of 10-50% following the advent of HAART. However long term use of HAART on oral health status of HIV infected subjects is poorly documented. Also antifungal agents can effectively treat mucosal candidiasis. However their use can lead to colonization with less susceptible strains among normal susceptible strains.

AIMS AND OBJECTIVES

To know the candidal carriage rate (i.e. presence/absence of candidal growth), candidal density(CFUs/ml) & species variations (species diversity) in HIV positive individuals with and without highly active anti-retroviral therapy (HAART), attending the regional voluntary Counselling and Confidential Testing Centre (VCCTC).

MATERIALS AND METHODS

The study population were categorized into 3 groups. Method followed were Germ tube test, Chlamydospore formation test, CHROM-Agar test.

RESULTS

Quantification comparison study of candidal carriage rate, density with detection of various candidal species in the oral cavity of HIV-positive individuals with and without HAART therapy was conducted.

CONCLUSION

HIV positive individuals with HAART therapy treatment prooved higher candidal carriage rate and lower density than Non-HAART category.

Prevalence of different fungal species in Saliva and Swab samples of patients undergoing Radiotherapy for Oral Cancer

Oral cancer is one of the leading causes of morbidity and mortality globally. There is a lack of studies on the growth of different Candida species in swab pre and post-radiotherapy. Hence, this study aimed to determine different Candida species in the oral cavity of patients who undergo radiotherapy. The study included 50 patients with oral cancer scheduled to undergo radiotherapy. Both saliva and swab samples were collected from all the patients before and after two- and six weeks of starting the radiotherapy. Similar inoculation was performed using the salivary swabs and incubated aerobically at 37°C for 48h. After 48h, culture plates were removed from the incubator and observed for the growth of different fungal species based on the color of the colonies. The culture of samples from patients with oral cancer resulted in the growth of 68% of Candida species in saliva and 44% in swab before initiating radiation. Unlike baseline findings, Candida albicans were identified in a higher number in swab samples (44%) than saliva (24%) post two weeks of radiotherapy. All saliva samples were positive to candida species, in which Candida albicans shows high prevalence (24%). After six weeks of radiotherapy, in the swab, 30% of samples were positive for Candida albicans, and 18% of samples were positive for non-albicans species. Before radiotherapy, at two weeks and six weeks of radiotherapy, saliva samples showed a higher prevalence of Candidal species compared to swab samples. The combination of other Candida species was also higher in saliva samples compared to swab samples during radiotherapy.

Update on Candida krusei, a potential multidrug-resistant pathogen

Although Candida albicans remains the main cause of candidiasis, in recent years a significant number of infections has been attributed to non-albicans Candida (NAC) species, including Candida krusei. This epidemiological change can be partly explained by the increased resistance of NAC species to antifungal drugs. C. krusei is a diploid, dimorphic ascomycetous yeast that inhabits the mucosal membrane of healthy individuals. However, this yeast can cause life-threatening infections in immunocompromised patients, with hematologic malignancy patients and those using prolonged azole prophylaxis being at higher risk. Fungal infections are usually treated with five major classes of antifungal agents which include azoles, echinocandins, polyenes, allylamines, and nucleoside analogues. Fluconazole, an azole, is the most commonly used antifungal drug due to its low host toxicity, high water solubility, and high bioavailability. However, C. krusei possesses intrinsic resistance to this drug while also rapidly developing acquired resistance to other antifungal drugs. The mechanisms of antifungal resistance of this yeast involve the alteration and overexpression of drug target, reduction in intracellular drug concentration and development of a bypass pathway. Antifungal resistance menace coupled with the paucity of the antifungal arsenal as well as challenges involved in antifungal drug development, partly due to the eukaryotic nature of both fungi and humans, have left researchers to exploit alternative therapies. Here we briefly review our current knowledge of the biology, pathophysiology and epidemiology of a potential multidrug-resistant fungal pathogen, C. krusei, while also discussing the mechanisms of drug resistance of Candida species and alternative therapeutic approaches.

ESCMID* guideline for the diagnosis and management of Candida diseases 2012: non-neutropenic adult patients

This part of the EFISG guidelines focuses on non-neutropenic adult patients. Only a few of the numerous recommendations can be summarized in the abstract. Prophylactic usage of fluconazole is supported in patients with recent abdominal surgery and recurrent gastrointestinal perforations or anastomotic leakages. Candida isolation from respiratory secretions alone should never prompt treatment. For the targeted initial treatment of candidaemia, echinocandins are strongly recommended while liposomal amphotericin B and voriconazole are supported with moderate, and fluconazole with marginal strength. Treatment duration for candidaemia should be a minimum of 14 days after the end of candidaemia, which can be determined by one blood culture per day until negativity. Switching to oral treatment after 10 days of intravenous therapy has been safe in stable patients with susceptible Candida species. In candidaemia, removal of indwelling catheters is strongly recommended. If catheters cannot be removed, lipid-based amphotericin B or echinocandins should be preferred over azoles. Transoesophageal echocardiography and fundoscopy should be performed to detect organ involvement. Native valve endocarditis requires surgery within a week, while in prosthetic valve endocarditis, earlier surgery may be beneficial. The antifungal regimen of choice is liposomal amphotericin B +/- flucytosine. In ocular candidiasis, liposomal amphotericin B +/- flucytosine is recommended when the susceptibility of the isolate is unknown, and in susceptible isolates, fluconazole and voriconazole are alternatives. Amphotericin B deoxycholate is not recommended for any indication due to severe side effects.

Isolation, identification, and carriage of candidal species in PHLAs and their correlation with immunological status in cases with and without HAART

AIMS AND OBJECTIVES

To know the prevalence of Candidal colonization, and to isolate and know the Candidal species prevalent in the oral cavity from the oral rinse samples collected from the individuals attending to the Voluntary Counseling and Confidential Testing Center (VCCTC) and the antiretro-viral therapy (ART) Center at Government General Hospital, Guntur, Andhra Pradesh, South India.

MATERIALS AND METHODS

The study group consisted of 50 HIV negative asymptomatic individuals (Group I); 50 HIV positive individuals (people living with HIV AIDS [PLWHA's]), who are naïve to antiretro-viral therapy (direct walk-in clients of VCCTC) (Group II); and 50 HIV positive individuals with CD4+ count less than 250 and who are started on highly active anti retroviral therapy (HAART) (Group III). Routine mycological tests for the isolation of pure cultures of Candida and also the speciation procedures were done.

RESULTS

In the study group, 53 (Group I=11; Group II=23; Group III=19) were culture positive. The prevalence of Candida was comparatively high in the age range between 41-50 years in Group II; 51-60 years, in Group III. A male predominance was observed in the Group I (M:F=16:6) and Group III (M:F=20:18), with a slight female predominance in the Group II (F:M=24:22). The overall culture positivity was 35.3%. Candida albicans was the highest prevalent species (47.17% of the isolates). A comparison of the culture positivity with the CD(4) counts of the study subjects was statistically highly significant. A pair wise comparison of the culture positivity with that of the colony forming units/mL from the subjects showed a high significance between Group I and Group II, and between Group I and Group III.

CONCLUSION

Candidal infections in immuno compromised patients are often severe, rapidly progressive, and difficult to treat and such patients have a definitive risk of developing oral candidiasis wherein, even the members of the normal oral flora may become pathogenic. Candida albicans is the common isolate. Nonalbicans species are also emerging as opportunistic pathogens. In view of this changing pattern, it is strongly recommended that species identification can help in much better treatment strategies, and thus, gain a good control over the disease. The findings of this study would be helpful in any further studies which, if done prospectively on a larger cohort, can be confirmatory.

Clinical practice guidelines for the management of candidiasis: 2009 update by the Infectious Diseases Society of America

Guidelines for the management of patients with invasive candidiasis and mucosal candidiasis were prepared by an Expert Panel of the Infectious Diseases Society of America. These updated guidelines replace the previous guidelines published in the 15 January 2004 issue of Clinical Infectious Diseases and are intended for use by health care providers who care for patients who either have or are at risk of these infections. Since 2004, several new antifungal agents have become available, and several new studies have been published relating to the treatment of candidemia, other forms of invasive candidiasis, and mucosal disease, including oropharyngeal and esophageal candidiasis. There are also recent prospective data on the prevention of invasive candidiasis in high-risk neonates and adults and on the empiric treatment of suspected invasive candidiasis in adults. This new information is incorporated into this revised document.

Early diagnosis of candidiasis in non-neutropenic critically ill patients

OBJECTIVE

To determine a method for the early diagnosis of candidiasis in non-neutropenic critically ill patients in order to reduce mortality.

METHODS

A prospective study in non-neutropenic critically patients in whom Candida spp. were detected, was made in an intensive care unit (ICU) during an 8-year period from 3389 patients admitted. A diagnostic and therapeutic protocol was designed. Invasive candidiasis was defined according to dissemination and multifocality.

RESULTS

Candida spp. were found in 145 cases (4.3%): 120 (83%) were considered as invasive candidiasis and 25 as colonisation (17%). The hospital mortality was 46% (67/145). A post-mortem study was carried out in 54% (36/67) of hospital deaths. Candida albicans was the most frequently isolated species (87%), followed by Candida glabrata (18%). There were 24 candidemias and three cases of endophtalmitis. Digestive and respiratory samples and non-C. albicans yeasts were risk factors for invasive candidiasis. The mortality rate was related statistically to invasive candidiasis and inversely to the appropriate antifungal treatment.

CONCLUSIONS

Invasive candidiasis is related to digestive and respiratory samples and to the presence of non-C. albicans species. A simpler definition of invasive candidiasis in non-neutropenic critically ill patients will permit more rapid and accurate specific antifungal therapy.

Pneumonia due to Candida krusei

A case of post-transplantation pneumonia due to Candida krusei is reported. A 42-year-old man was admitted 28 days after heart transplantation with cough, pleuritic pain and fever. A chest computed tomograph showed multiple alveolar infiltrates bilaterally. He received broad-spectrum antibiotics, fluconazole for oral candidiasis, and cotrimoxazole for possible Pneumocystis carinii. A short-lived period of improvement was followed by respiratory failure. Cultures of bronchial washings grew C. krusei and C. albicans. The infection was documented by histology and culture obtained by transthoracic aspiration. Treatment with amphotericin B was initiated, but the patient died. Histology and culture of a pulmonary specimen, obtained immediately post mortem, further documented the infection with C. krusei.

Yeast-like microorganisms in eye infections

The proportion of yeast species involved in eye infections in 11 patients was examined. The presence of yeast organisms as causative agents of endophthalmitis was found in corneal smears (n = 4), conjunctival swabs (4), and vitreous fluid (3). Altogether 5 strains of Candida albicans, 2 strains of C. krusei and one strain each of C. guilliermondii, C. parapsilosis, C. tropicalis and Cryptococcus neoformans were isolated from the clinical material. The hematogenic origin of endophthalmitis was proved in 7 cases on the basis of positive blood samples and in 2 cases by the isolation of yeasts from the tip of an intravenous catheter. Endophthalmitis-supporting risk factors such as indwelling intravenous catheters, prolonged use of broad-spectrum antibiotics and chemotherapy, surgical intervention, diabetes mellitus, and malignancy were observed in the patients.

Non-albicans Candida spp. causing fungaemia: pathogenicity and antifungal resistance

Non-albicans Candida (NAC) species cause 35-65% of all candidaemias in the general patient population. They occur more frequently in cancer patients, mainly in those with haematological malignancies and bone marrow transplant (BMT) recipients (40-70%), but are less common among intensive care unit (ITU) and surgical patients (35-55%), children (1-35%) or HIV-positive patients (0-33%). The proportion of NAC species among Candida species is increasing: over the two decades to 1990, NAC represented 10-40% of all candidaemias. In contrast, in 1991-1998, they represented 35-65% of all candidaemias. The most common NAC species are C. parapsilosis (20-40% of all Candida species), C. tropicalis (10-30%), C. krusei (10-35%) and C. glabrata (5-40%). Although these four are the most common, at least two other species are emerging: C. lusitaniae causing 2-8% of infections, and C. guilliermondii causing 1-5%. Other NAC species, such as C. rugosa, C. kefyr, C. stellatoidea, C. norvegensis and C. famata are rare, accounting for less than 1% of fungaemias in man. In terms of virulence and pathogenicity, some NAC species appear to be of lower virulence in animal models, yet behave with equal or greater virulence in man, when comparison is made with C. albicans. Mortality due to NAC species is similar to C. albicans, ranging from 15% to 35%. However, there are differences in both overall and attributable mortality among species: the lowest mortality is associated with C. parapsilosis, the highest with C. tropicalis and C. glabrata (40-70%). Other NAC species including C. krusei are associated with similar overall mortality to C. albicans (20-40%). Mortality in NAC species appears to be highest in ITU and surgical patients, and somewhat lower in cancer patients, children and HIV-positive patients. There is no difference between overall and attributable mortality, with the exception of C. glabrata which tends to infect immunocompromised individuals. While the crude mortality is low, attributable mortality (fungaemia-associated mortality) is higher than with C. albicans. There are several specific risk factors for particular NAC species: C. parapsilosis is related to foreign body insertion, neonates and hyperalimentation; C. krusei to azole prophylaxis and along with C. tropicalis to neutropenia and BMT; C. glabrata to azole prophylaxis, surgery and urinary or vascular catheters; C. lusitaniae and C. guilliermondii to previous polyene (amphotericin B or nystatin) use; and C. rugosa to burns. Antifungal susceptibility varies significantly in contrast to C. albicans: some NAC species are inherently or secondarily resistant to fluconazole; for example, 75% of C. krusei isolates, 35% of C. glabrata, 10-25% of C. tropicalis and C. lusitaniae. Amphotericin B resistance is also seen in a small proportion: 5-20% of C. lusitaniae and C. rugosa, 10-15% of C. krusei and 5-10% of C. guilliermondii. Other NAC species are akin to C. albicans-susceptible to both azoles and polyenes (C. parapsilosis, the majority of C. guilliermondii strains and C. tropicalis). Therefore, 'species directed' therapy should be administered for fungaemia according to the species identified-amphotericin B for C. krusei and C. glabrata, fluconazole for other species, including polyene-resistant or tolerant Candida species (C. lusitaniae, C. guilliermondii). In vitro susceptibility testing should be performed for most species of NAC in addition to removal of any foreign body to optimize management.

In vitro activity of nystatin compared with those of liposomal nystatin, amphotericin B, and fluconazole against clinical Candida isolates

We investigated the in vitro activity of nystatin and liposomal nystatin against 103 Candida isolates to determine the effect of both time and medium on MICs. We also compared the nystatin MICs with those of amphotericin B and fluconazole. Testing was performed in accordance with the National Committee for Clinical Laboratory Standards M27-A microdilution methodology with RPMI 1640, RPMI 1640 supplemented with glucose to 2% (RPMI-2), and antibiotic medium 3 supplemented with glucose to 2% (AM3). While nystatin MICs were similar to or slightly lower than liposomal nystatin MICs in RPMI 1640 and RPMI-2, they were markedly higher than liposomal nystatin MICs in AM3. Use of AM3 and determination of the MIC after 24 h of incubation provided a slightly wider range of liposomal nystatin MICs (0.06 to >16 microg/ml). Under these conditions, the MICs at which 90% of isolates were inhibited of nystatin and liposomal nystatin were 2 and 1 microg/ml, respectively. Nystatin and liposomal nystatin in general showed good activity against all Candida spp. tested. Although the MICs of nystatin and liposomal nystatin tended to rise in parallel with the amphotericin B MICs, nystatin and liposomal nystatin MICs of 1 to 2 and 0.5 to 1 microg/ml, respectively, were obtained for seven and six, respectively, of nine isolates for which amphotericin B MICs were >or=0.25 microg/ml. No correlation between fluconazole and nystatin or liposomal nystatin MICs was observed. As amphotericin B MICs of >or=0.25 microg/ml correlate with in vitro resistance, these results suggest that liposomal nystatin might have activity against some amphotericin B-resistant isolates. In vivo testing in animal models is required for clarification of this issue.

Prospective study of fungaemia in a single cancer institution over a 10-y period: aetiology, risk factors, consumption of antifungals and outcome in 140 patients

Over a 10-y period (1989-99) we prospectively evaluated all patients with fungaemia among 16,555 admissions (21,004 blood cultures) at a national cancer referral institution in the Slovak Republic. A prospective protocol was completed on 140 patients with fungaemia, which was then analysed in terms of aetiology, clinical characteristics, potential risk factors and outcome. The most frequently isolated organism was C. albicans, in 75 patients (52.9%), followed by non-albicans Candida spp. in 45 patients (32.1%). Non-Candida spp. yeasts represented 16 episodes in 16 patients (11.4%). Moulds caused 4 episodes in 4 patients (3.6% of all fungaemias) and all were caused by Fusarium spp. Mucositis (p = 0.025), > or = 3 positive blood cultures (p = 0.02), acute leukaemia (p = 0.00001), neutropenia (p = 0.0015), quinolone prophylaxis (p < 0.000005) and breakthrough fungaemia (p = 0.004) during prophylaxis with fluconazole (p = 0.03) and itraconazole (p = 0.005) were significantly more associated with non-Candida than C. albicans spp. Furthermore, attributable mortality was higher in the subgroup of non-Candida than C. albicans spp. (50.0 vs. 18.7%, p < 0.02). The only independent risk factor for inferior outcome was antifungal therapy of < 10 d duration (odds ratio 2.1, 95% confidence interval, p < 0.001). Aetiology, neutropenia and mucositis were not independent risk factors for higher mortality in multivariate analysis; however, they were risk factors for inferior outcome in univariate analysis (p < 0.05-0.005).

[Nosocomial fungemias in a general hospital. Epidemiology and prognostic factors. Prospective study 1993-1998]

BACKGROUND

Nosocomial fungemias are infections with a high mortality rate. In last years the incidence of these infections has increased probably because of the growing population of immunocompromised patients who undergo aggressive diagnostic and therapeutic techniques.

OBJECTIVE

To know the epidemiologic characteristics, risk factors, clinical features and prognosis of fungemia.

PATIENTS AND METHODS

We prospectively evaluated all the patients with proven fungemia in our center during a 5 year-period. After finishing antifungal treatment a minimum follow-up of 1 month was carried out. Fungal isolation and identification were performed by standard tests.

RESULTS

During the period of study we evaluated 81 patients with an episode of nosocomial fungemia. Global incidence was 0,9 episodes per thousand admitted patients. Candida albicans was the more frequently isolated species (n=53), followed by C. parapsilosis (n=11), C. tropicalis (n=6) and C. glabrata (n=5). Most of the patients had a central intravenous line and were on parenteral nutrition therapy. All of them previously received at least one course of broad-spectrum antibiotics. Overall mortality was 49,6%. A worst prognosis was significantly associated with: age over 65 years, surgical procedures during present admission, leucocytosis, shock, and delay in antifungal treatment.

CONCLUSIONS

Fungal bloodstream infection incidence is high in our environment. It is associated with a high mortality rate, specially in patients in whom the beginning of antifungal treatment was delayed. A higher clinical suspicion index may improve the poor outcome in these patients.

Longitudinal 10-year prospective survey of fungaemia in Slovak Republic: trends in etiology in 310 episodes. Slovak Fungaemia study group

A 10-year prospective survey of fungaemia in the Slovak Republic, involving 31 microbiology laboratories and 71 hospitals, was conducted from 1989-1998 (10 years): 310 fungaemias were analyzed for etiology, clinical characteristics, therapy, and outcome. C. albicans was responsible for 191 (61.6%) fungaemias, non-albicans Candida spp. (NAC) for 97 (31.3%), non-Candida yeasts for 18 (5.8%) and moulds (Fulsarium spp.) for four fungaemias. The most frequent NAC isolated from blood cultures were C. parapsilosis--30 (9.7%), C. krusei--18 (5.8%), C. tropicalis--14 (4.5%), and C. glabrata--10 (3.2%). Secular trends in etiology showed a sustaining decrease of C. albicans (from 100% in 1989 to 50.7% in 1998) and increase of NAC (from 0% in 1989-1990 to 46.3% in 1998). Non-Candida yeasts and moulds showed a stable proportion during the investigated period. There were statistically significant differences in etiology of fungaemia various subgroups of patients: non-albicans Candida spp. was significantly more frequent observed among subgroups of patients with pancreatitis and coma (53.3% vs. 31.3%, p < or = 0.02) and less frequently in the subgroup of neonates (15.0% vs. 31.3%, p < or = 0.006). Vice versa, C. albicans appeared more frequently in neonates (85%).

Retrospective study of candidemia in patients with hematological malignancies. Clinical features, risk factors and outcome of 76 episodes

A retrospective study of 76 episodes of candidemia in 73 patients with underlying hematological malignancy, from 1988 until 1997, has been conducted to evaluate the clinical characteristics and to ascertain the variables related to the onset and the outcome of candidemia. The most frequent malignancy was acute myeloid leukemia (29 episodes). Candidemia developed mainly during aplasia in patients refractory to chemotherapy (42%). In 65 episodes (86%) the patients were neutropenic (ANC <1 x 10(9)/l) before the candidemia diagnosis for a median time of 13 d, and in 53 episodes (70%) at microbiological diagnosis of candidemia ANC was <1 x 10(9)/l. Candida albicans was the most frequently isolated etiologic agent (31 episodes), but C. non-albicans species sustained the majority of candidemia. Seventeen candidemias developed during azoles prophylaxis. One month after the diagnosis of candidemia, 26 patients died. In 19 cases, death was attributable to candidemia. The case-control study demonstrated, at univariate analysis, that the colonization with Candida. spp. (p=0.004), antimycotic prophylaxis (p=0.01), presence of central venous catheter (p=0.01), neutropenia (p=0.002), and the use of glycopeptide (p=0.0001) increased the risk of candidemia. Using multivariate regression analysis only colonization with Candida spp. and the previous therapy with glycopeptide were associated with a significantly increased risk. Acute mortality, expressed by a cumulative probability of survival at 30 d from diagnosis of candidemia, was 0.67 (95% C.I. 0.55-0.77) and was significantly reduced in patients with neutrophils <1 x 10(9)/l when compared to those with neutrophils >1 x 10(9)/l (p at Mantel-Cox=0.029). Overall cumulative probability of survival at 1 yr was 0.38 (95% C.I. 0.27-0.49) and only the treatment with Amfotericin B significantly reduced the risk of death.

Nosocomial Candida krusei fungemia in cancer patients: report of 10 cases and review

The risk factors, therapy and outcome of ten cases of fungemia due to Candida krusei, appearing during the last 10 years in a single national cancer institution, are analyzed. Univariate analyses did not find any specific risk factors in comparison to 51 Candida albicans fungemias appearing at the same institution and with a similar antibiotic policy. Association with prior fluconazole prophylaxis was not confirmed because only one case appeared in a patient previously treated with fluconazole. However, attributable and crude mortality due to C. krusei fungemias was higher than for C. albicans fungemia. The authors review 172 C. krusei fungemias published within the last 10 years to compare with the incidence, therapy and outcome of C. krusei fungemia from our cancer institute.

Antifungal activity of voriconazole (UK-109,496), fluconazole and amphotericin B against hematogenous Candida krusei infection in neutropenic guinea pig model

Voriconazole (UK-109,496) is a new triazole with in vitro activity against a wide spectrum of fungi including yeasts intrinsically resistant to fluconazole such as Candida krusei. In this study the efficacy of voriconazole was compared to amphotericin B and fluconazole in a neutropenic guinea pig model of hematogenously disseminated C. krusei infection. In guinea pigs, neutropenia was established by using cyclophosphamide (intraperitoneally, i.p., 100 mg/kg on day 1 and 4), and dexamethasone (orally, 2 mg/kg/day, for 8 days). Neutropenic guinea pigs were infected with 0.5 ml of yeast cell suspension (1 x 10(8) CFU) intravenously. Challenged animals were treated with antifungals starting 1 h postinfection for 7 days. The animals were divided into five groups: untreated control, amphotericin B (1 mg/kg i.p. on alternate days), fluconazole (20 mg/kg orally twice daily), and voriconazole (two groups: 5 and 10 mg/kg orally twice daily) groups. Guinea pigs were sacrificed 1 day after the last treatment. Brain, liver, and kidneys were removed and weighed, tissues were homogenized and fungal burden determined by serial quantitative counts. Voriconazole at dosages of 5 or 10 mg/kg b.i.d. was shown to be significantly more efficacious than either amphotericin B or fluconazole in eradicating C. krusei from brain, liver and kidney tissue. These data indicate that voriconazole could be efficacious for the treatment of infections caused by fluconazole-resistant Candida, such as C. krusei.

Mechanism of fluconazole resistance in Candida krusei

The mechanisms of fluconazole resistance in three clinical isolates of Candida krusei were investigated. Analysis of sterols of organisms grown in the absence and presence of fluconazole demonstrated that the predominant sterol of C. krusei is ergosterol and that fluconazole inhibits 14alpha-demethylase in this organism. The 14alpha-demethylase activity in cell extracts of C. krusei was 16- to 46-fold more resistant to inhibition by fluconazole than was 14alpha-demethylase activity in cell extracts of two fluconazole-susceptible strains of Candida albicans. Comparing the carbon monoxide difference spectra of microsomes from C. krusei with those of microsomes from C. albicans indicated that the total cytochrome P-450 content of C. krusei is similar to that of C. albicans. The Soret absorption maximum in these spectra was located at 448 nm for C. krusei and at 450 nm for C. albicans. Finally, the fluconazole accumulation of two of the C. krusei isolates was similar to if not greater than that of C. albicans. Thus, there are significant qualitative differences between the 14alpha-demethylase of C. albicans and C. krusei. In addition, fluconazole resistance in these strains of C. krusei appears to be mediated predominantly by a reduced susceptibility of 14alpha-demethylase to inhibition by this drug.

Epidemiology of infectious complications in cancer patients

Patients with underlying malignancies are at risk for a wide array of infectious diseases that cause significant morbidity and mortality. To develop a clear etiologic understanding of the infectious agents involved first requires a knowledge of the factors that predispose to infection. Neutropenia is clearly the single most important risk factor for infection in the cancer patient. However, a variety of both host and treatment-associated factors act together to predispose these patients to opportunistic infections. Approaching the individual malignancies with a knowledge of the underlying risk factors helps logically guide diagnosis and therapy. The astute clinician must also be aware of new and emerging infections in this patient population. As new pathogens are discovered and established pathogens become increasingly drug resistant, they will continue to present challenges for physicians caring for these patients in the years ahead.

Antifungal prophylaxis during neutropenia and immunodeficiency

Fungal infections represent a major source of morbidity and mortality in patients with almost all types of immunodeficiencies. These infections may be nosocomial (aspergillosis) or community acquired (cryptococcosis), or both (candidiasis). Endemic mycoses such as histoplasmosis, coccidioidomycosis, and penicilliosis may infect many immunocompromised hosts in some geographic areas and thereby create major public health problems. With the wide availability of oral azoles, antifungal prophylactic strategies have been extensively developed. However, only a few well-designed studies involving strict criteria have been performed, mostly in patients with hematological malignancies or AIDS. In these situations, the best dose and duration of administration of the antifungal drug often remain to be determined. In high-risk neutropenic or bone marrow transplant patients, fluconazole is effective for the prevention of superficial and/or systemic candidal infections but is not always able to prolong overall survival and potentially selects less susceptible or resistant Candida spp. Primary prophylaxis against aspergillosis remains investigative. At present, no standard general recommendation for primary antifungal prophylaxis can be proposed for AIDS patients or transplant recipients. However, for persistently immunocompromised patients who previously experienced a noncandidal systemic fungal infection, prolonged suppressive antifungal therapy is often indicated to prevent a relapse. Better strategies for controlling immune deficiencies should also help to avoid some potentially life-threatening deep mycoses. When prescribing antifungal prophylaxis, physicians should be aware of the potential emergence of resistant strains, drug-drug interactions, and the cost. Well-designed, randomized, multicenter clinical trials in high-risk immunocompromised hosts are urgently needed to better define how to prevent severe invasive mycoses.

Rapid identification and fingerprinting of Candida krusei by PCR-based amplification of the species-specific repetitive polymorphic sequence CKRS-1

A PCR method was developed to identify and fingerprint Candida krusei isolates simply and rapidly. The primer pair Arno1 and Arno2 was designed to amplify the polymorphic species-specific repetitive sequence CKRS-1 (C. krusei repeated sequence 1) that we identified in the nontranscribed intergenic regions (IGRs) of rRNA genes in C. krusei LMCK31. The specificity, sensitivity, reproducibility, and fingerprinting ability of the PCR assay were evaluated. Amplification products were obtained from all 131 C. krusei isolates studied. No other yeast species of medical importance (n = 26), including species similar to C. krusei, species of pathogenic filamentous fungi, or a variety of pathogenic bacteria, yielded a PCR product with these primers. This PCR assay allowed for the identification of C. krusei in less than 6 h. The PCR assay was sensitive enough to detect as little as 10 to 100 fg of C. krusei-purified DNA and proved to be reproducible. Since amplification products varied both in number and in molecular weight according to the strains, PCR patterns allowed strains to be distinguished. To ascertain the epidemiological usefulness of this PCR fingerprinting, the patterns of the 131 isolates were compared. A total of 95 types which corresponded to 95 independent strains were delineated (discriminatory power = 1 with n = 95). Comparison of the results of PCR fingerprinting and those of fingerprinting with the CkF1,2 probe showed that they concurred. In addition, this work yields insights into the mechanisms involved in generating polymorphisms in the IGRs of C. krusei. Since this method is simpler and faster than established identification and genotyping methods of this important pathogenic species, it is a critical improvement for clinical microbiology laboratories relevant not only to diagnosis but also to epidemiology.

Clinical and laboratory diagnosis of invasive candida infection in neutropenic patients

Cancer patients, especially those with acute leukaemia, represent a group that has the greatest risk for deep fungal infection. Almost no cases were seen before the advent of modern chemotherapy, and prior to the availability of antibacterial agents, less than 5% of patients with acute leukaemia died of fungal infection. These infections are now responsible for 40% or more of the deaths at some institutions. Candida species continues to be the most common fungal pathogen. Rapid and specific diagnosis of invasive candiosis enabling early effective therapy is therefore an important measure for reducing mortality in patients. Here the current status of clinical and laboratory diagnosis of invasive candida infection in neutropenic patients is discussed and recommendations made as to future development programmes.

Strain variation among and antifungal susceptibilities of isolates of Candida krusei

Candida krusei is an emerging pathogen that is well known for its propensity to develop resistance to fluconazole and other azoles. Despite the potential clinical significance of C. krusei, little is known of its epidemiology and genetic diversity as defined by the newer DNA-based typing methods. We investigated the genotypic diversity and antifungal susceptibility of 67 clinical isolates from 44 patients and 5 health care workers from six different medical centers. Strain delineation was performed by restriction endonuclease analysis of genomic DNA (REAG) with the restriction enzyme HinfI followed by conventional electrophoresis. The susceptibility of the isolates to the antifungal agents amphotericin B, flucytosine, fluconazole, and itraconazole was determined by methods recommended by the National Committee for Clinical Laboratory Standards. The MICs at which 90% of the isolates were inhibited ranged from 1.0 microgram/ml for itraconazole to 64 micrograms/ml for fluconazole. In general, isolates from a given patient, or epidemiologically related isolates from a single institution, were identical by molecular typing methods. Epidemiologically unrelated isolates were distinctly different by the REAG typing method employed. These data document the genetic diversity and antifungal susceptibility of clinical isolates of C. krusei.

Species-specific identification of Candida krusei by hybridization with the CkF1,2 DNA probe

The species specificity of the Candida krusei DNA fingerprinting probe CkF1,2 has been investigated. A total of 149 pathogenic and nonpathogenic fungal and bacterial DNAs were screened with CkF1,2. The probe was cold labeled with peroxidase, and its specificity was assessed by using Southern blot, dot blot, and colony blot hybridization. Its sensitivity was determined by dot blot hybridization. The CkF1,2 probe proved to be species specific. It hybridized with DNA for the 112 C. krusei strains studied, whereas it failed to hybridize under low-stringency conditions to 37 DNAs from 27 different yeast species, including Candida albicans, Candida glabrata, Candida norvegensis, Candida inconspicua, Candida tropicalis, Candida valida, Candida zeylanoides, and Yarrowia lipolytica, as well as DNAs from the filamentous fungi and bacteria tested. However, CkF1,2 hybridized strongly with DNA of the yeast species Issatchenkia orientalis, the putative ascogenous perfect state of C. krusei. Amounts as small as 60 to 120 ng of C. krusei target DNA were detected by dot blot hybridization with CkF1,2. It permitted the direct screening of colony blots for early identification. The CkF1,2 probe has potential value as a diagnostic reagent for identifying C. krusei.

Catheter-related complications of cancer therapy

Although the management of CVC-related infection appears complex and at times the literature seems to be contradictory, simple guidelines can direct the clinician in a stepwise fashion. Knowledge of the pathogenesis of each organism and the immune status of the host is crucial to decide whether catheter removal or retention is indicated. For example, in general, GNB bacteremia does not immediately prompt catheter removal in a neutropenic patient but does in a nonneutropenic host because of the gastrointestinal source of the former and a primary catheter source in the latter. In summary, as more CVCs are inserted in patients undergoing chemotherapeutic, antimicrobial, transfusional, and nutritional supportive care, novel approaches to prevention and treatment of the associated infectious complications inherent with such devices are needed. A multifaceted approach from impregnated catheters to local catheter-site antisepsis was reviewed. We may find, however, that as simple handwashing between patients is crucial to infection control, so too is a trained catheter-care team using total barrier precautions and ensuring proper local catheter maintenance critical to preventing CVC-related infections.

Emerging fungal infections in cancer patients

The increasing number of reports in cancer patients that describe unusual or new fungal pathogens in severe systemic infections may be due, in part, to new treatment regimens but also to increased recognition of clinical disease by physicians and unusual organisms by microbiologists. Identification of these pathogens requires specialized expertise but the diagnosis may often be too late to permit effective therapeutic intervention. An unfortunate limitation of current antifungal agents is their limited efficacy in the heavily immunosuppressed, even when the drugs show good activity in vitro. Infections with Candida spp., and non-Candida yeasts and moulds are often disseminated and are frequently fatal in patients with severe immunosuppression. Therapeutic outcomes could be improved with more precise and rapid diagnostic procedures, standardized treatments for each pathogen and improved therapeutic agents. Liposomal amphotericin B formulations, new azole antifungals, more aggressive surgery and haemopoietic growth factors may improve the poor outcome that currently occurs with many of those infections.

Treatment and Control of Colonization in the Prevention of Nosocomial Infections

Patients frequently develop nosocomial infections that are caused by normal flora colonizing the patient at the time of admission, or by exogenous pathogens that are acquired and subsequently colonize the patient after admission to the hospital. To prevent nosocomial infections, a variety of strategies have been used either to prevent colonization from occurring, to eradicate colonizing organisms, or to prevent the progression from colonization to infection. These strategies include implementation of infection control measures designed to prevent acquisition of exogenous pathogens, eradication of exogenous pathogens from patients or personnel who have become colonized, suppression of normal flora, prevention of colonizing flora from entering sterile body sites during invasive procedures, microbial interference therapy, immunization of high-risk patients, and modification of antibiotic utilization practices. Because strategies that require widespread use of antimicrobial agents to suppress or eradicate colonizing organisms tend to promote emergence of multidrug-resistant pathogens, greater emphasis should be given to those strategies that prevent colonization from occurring or employ techniques other than administration of prophylactic antibiotics to eradicate colonization. Restricting inappropriate use of antibiotics should reduce the frequency with which patients become colonized and infected with multidrug-resistant organisms.

Targeting fungi: a challenge

Invasive fungal infections are more commonly identified in various categories of patients, mainly in cancer patients but also in those undergoing organ transplantation, patients in intensive care units, and those with AIDS. There is a great need to increase the awareness of practitioners who are still underestimating the morbidity and mortality relating to invasive fungal infections, and to stress the economic burden for the society and healthcare systems of invasive fungal infections. The list of fungal pathogens causing life-threatening complications has also increased recently, with the emergence of unusual fungi being more frequently identified in such settings. Early diagnosis of invasive fungal infections is still a major challenge for the clinician at the bedside. Identification of state-of-the-art management is also a difficult task for the clinical scientist involved in the assessment of optimal strategies to prevent and to treat those invasive fungal infections, although major progress has occurred in the last 5 years with the development of new, safe, and effective antifungal agents. Empiric therapy remains a very controversial issue that should be further investigated in high-quality clinical trials. Overall, clinical research in this difficult field requires independent and objective analysis; only large multicenter clinical trials can address these critical issues and rapidly provide convincing results leading to a better prognosis of patients with invasive fungal infections. These complications still represent too often an obstacle to successful control of severe underlying diseases. Clinical research on the appropriate ways to target fungi will not only define state-of-the-art management but also identify ineffective or redundant treatments. Such an approach will make a substantial contribution to the care of the high-risk patients within the next decade and will preserve our capacity for medical excellence.

Efficacy of itraconazole in treating AIDS-associated infections due to Candida krusei

Candida krusei is an emerging pathogen, both in HIV negative immunocompromised patients and in HIV seropositive patients. Its onset appears to be due, at least in part, to the use of fluconazole. In HIV positive patients, a long term prophylactic use of fluconazole may select some less pathogenic Candida species, as C. krusei, that may determine persistent oral candidiasis and emerge as systemic pathogen. Itraconazole appears efficacious in treating AIDS-associated C. krusei infections.

SCH 51048, a new antifungal triazole active against hematogenous Candida krusei infections in neutropenic mice

Candida krusei is increasingly recognized as an opportunistic pathogen in immunocompromised patients and is inherently resistant to fluconazole. We tested the in vivo efficacy of SCH 51048, an investigational antifungal triazole, in experimental hematogenous murine infection caused by two C. krusei isolates and compared its activity with those of amphotericin B and fluconazole. CF1 mice were immunosuppressed with cyclophosphamide and cortisone acetate and were challenged intravenously with infecting inocula of each C. krusei isolate. Treatment with SCH 51048 (50 or 100 mg/kg of body weight per day orally) or amphotericin B (2 mg/kg/day intraperitoneally) significantly prolonged the survival of infected mice and significantly reduced fungal titers in the kidneys (P < or = 0.05). Treatment with fluconazole (100 mg/kg/day orally) had no effect. Both dosages of SCH 51048 were as effective as amphotericin B in improving survival, but the higher dosage was significantly (P < or = 0.05) better in reducing the fungal burden in the kidneys of infected animals. A dose-dependent response was observed with SCH 51048 treatment, especially in organ clearance. Our results indicate that SCH 51048 is the first triazole that has in vivo activity against experimental infection with C. krusei and deserves further evaluation.

Ultrastructure of circulating immune complexes isolated from the blood plasma of patients suffering from infectious diseases

An original procedure which permits to isolate circulating immune complexes (CIC) from the blood plasma in a form of a dense pellet was developed. This procedure was applied for the ultrastructural analysis of CIC isolated from blood of healthy blood donors and patients suffering from Yersinia enterocolitica (YE) and Yersinia pseudotuberculosis (YP) infections. The here reported method of CIC isolation from blood plasma permitted to visualize CIC electronmicroscopically as amorphous masses of low, middle, and high electron density with inclusions of cell debris. In contrast to CIC of healthy blood donors, CIC of infected patients contained various bacteria and fungiformic structures. For the first time, this method made possible an ultrastructural demonstration of bacterial destruction outside of phagocytes in vivo. This method also permits to visualize and identify bacteria in cases of lingering forms of infection when hemoculture tests fail. Therefore, electronmicroscopic examination of CIC preparations from the blood plasma might be a very informative indicator of bacteriemia in the course of an infection process and serve as an indicator of therapeutic effects. In lingering forms of an infection process, ultrastructural analysis of CIC preparations can be of prognostic value and serve as an indicator of therapeutic effects. This method might be also advantageous as an additional test for the exposure of latent bacterial persistence in diagnostically complicated cases.

Typing of Candida krusei clinical isolates by restriction endonuclease analysis and hybridization with CkF1,2 DNA probe

The use of restriction endonuclease analysis and Southern hybridization with our new CkF1,2 DNA probe, cold labeled with peroxidase, for the typing of Candida krusei isolates has been investigated. Fifty-five clinical samples isolated from forty-five patients hospitalized in eight centers, one environmental strain, and two reference strains were evaluated. Patterns were analyzed by a computer-assisted method and compared by numerical analysis. Clearer and less ambiguous patterns were obtained by restriction with endonuclease HinfI. It generated 9 to 14 (average, 11) well-separated fragments in the range of 6.5 to 2.0 kb. Both their numbers and sizes varied greatly among the strains studied. The CkF1,2 probe hybridized with one to seven fragments of HinfI patterns. A total of 48 distinct types were distinguished among the 58 strains studied. HinfI and CkF1,2 patterns showed similarities of less than 83 and 75% for unrelated strains and more than 91 and 100% for related strains, respectively. The methods showed 100% typeability, 98% reproducibility, and a discriminatory power of 1. C. krusei isolates from each patient were distinct, whether from one hospital or from different hospitals. Multiple isolates from the same patient were identical, both over time and at different anatomic sites. An endogenous origin is suggested for the colonizing and infecting isolates among the 45 patients. The CkF1,2 probe enhanced discrimination of the strains and provided a definitive comparison for strain identity. Genetic linkages between isolates were assessed at the subspecies level, and 12 clusters were delineated. A typing scheme is proposed for epidemiological studies of C. krusei.

Oral azole drugs as systemic antifungal therapy

The oral azole drugs--ketoconazole, fluconazole, and itraconazole--represent a major advance in systemic antifungal therapy. Among the three, fluconazole has the most attractive pharmacologic profile, including the capacity to produce high concentrations of active drug in cerebrospinal fluid and urine. Ketoconazole, the first oral azole to be introduced, is less well tolerated than either fluconazole or itraconazole and is associated with more clinically important toxic effects, including hepatitis and inhibition of steroid hormone synthesis. However, ketoconazole is less expensive than fluconazole and itraconazole--an especially important consideration for patients receiving long-term therapy. All three drugs are effective alternatives to amphotericin B and flucytosine as therapy for selected systemic mycoses. Ketoconazole and itraconazole are effective in patients with the chronic, indolent forms of the endemic mycoses, including blastomycosis, coccidioidomycosis, and histoplasmosis; itraconazole is also effective in patients with sporotrichosis. Fluconazole is useful in the common forms of fungal meningitis--namely, coccidioidal and cryptococcal meningitis. In addition, fluconazole is effective for selected patients with serious candida syndromes such as candidemia, and itraconazole is the most effective of the azoles for the treatment of aspergillosis.

Candidemia: current epidemiologic characteristics and a long-term follow-up of the survivors

All consecutive patients with positive blood culture for Candida species over a 6-year period were evaluated to define recent epidemiologic characteristics of candidemia, and to assess the prevalence of late complications. We encountered 106 cases; medical records were available for 99 of them. The rate of candidemia was increasing until 1990, after which it declined. C. albicans was the most common species, but in the last 2 years, C. tropicalis and C. parapsilosis were emerging. Overall mortality rate was 54.5% without significant variation during the study period. Antifungal therapy was withheld in 24/99 cases (24.2%). Decision to withhold treatment was taken in 19/59 cases (32.2%) before the availability of fluconazole in 1990, compared with 5/40 cases (12.5%) afterward (p < 0.05). Follow-up was possible in 35 instances for an average period of 17.1 months (range: 1-48 months); 7 of these individuals, all with transient candidemia, were untreated. None of the survivors developed late complications. These findings demonstrate that candidemia appears to be declining since 1990, with a noticeable decrease in the prevalence of C. albicans but an increase in that of C. tropicalis and C. parapsilosis, that fewer patients are left untreated since fluconazole became available, and that the risk of late complications among the survivors is low.