Outbreak of fungemia due to Candida parapsilosis in a pediatric oncology unit

No-Touch Automated Disinfection System Based on Hydrogen Peroxide and Ethyl Alcohol Aerosols for Use in Healthcare Environments

Healthcare-related infections are sustained by various bacteria and fungi. In recent years, various technologies have emerged for the sanitation of healthcare-related environments. This study evaluated the effectiveness of a no-touch disinfection system that aerosolizes 5% hydrogen peroxide and 10% ethyl alcohol. After selecting an environment, the Total Bacterial Count and the Total Fungal Count in the air and on a surface of the room were determined to evaluate the effectiveness of the aerosolization system. In addition, sterile stainless-steel plates inoculated with S. aureus, P. aeruginosa, and Aspergillus spp. isolated from hospitalized patients and reference strains were used to evaluate the effectiveness of the system. For each organism, three plates were used: A (cleaned), B (not cleaned), and C (control). The A plates were treated with non-ionic surfactant and the aerosolization system, the B plates were subjected to the aerosolization system, and the plates C were positioned outside the room that was sanitized. Following sanitization, air and surface sampling was conducted, after which, swabs were processed for bacterial and fungal enumeration. The results showed that the air sanitization system had good efficacy for both bacteria and fungi in the air and on stainless-steel plates, particularly for the A plates.

Candidemia: Evolution of Drug Resistance and Novel Therapeutic Approaches

Candidemia and invasive candidiasis are the most common healthcare-associated invasive fungal infections, with a crude mortality rate of 25–50%. Candida albicans remains the most frequent etiology, followed by C. glabrata, C. parapsilosis and C. tropicalis. With the exception of a limited number of species (ie: C. krusei, C. glabrata and rare Candida species), resistance to fluconazole and other triazoles are quite uncommon. However, recently fluconazole-resistant C. parapsilosis, echinocandin-resistant C. glabrata and the multidrug resistant C. auris have emerged. Resistance to amphotericin B is even more rare due to the reduced fitness of resistant isolates. The mechanisms of antifungal resistance in Candida (altered drug-target interactions, reduced cellular drug concentrations, and physical barriers associated with biofilms) are analyzed. The choice of the antifungal therapy for candidemia must take into account several factors such as type of patient, presence of devices, severity of illness, recent exposure to antifungals, local epidemiology, organs involvement, and Candida species. The first-line therapy in non-neutropenic critical patient is an echinocandin switching to fluconazole in clinically stable patients with negative blood cultures and azole susceptible isolate. Similarly, an echinocandin is the drug of choice also in neutropenic patients. The treatment duration is 14 days after the first negative blood culture or longer in cases of organ involvement. An early removal of vascular catheter improves the outcome. The promising results of new antifungal molecules, such as the terpenoid derivative ibrexafungerp, the novel echinocandin with an enhanced half-life rezafungin, oteseconazole and fosmanogepix, representative of new classes of antifungals, are discussed.

Candidemia and its Risk Factors in Neonates and Children

Objectives: The present study was conducted to raise attention to the frequency of Candida spp. and evaluation of risk factors of candidemia in hospitalized neonates and children. Methods: Identification of Candida at species level was done using the PCR-RFLP method. The Candida albicans complex and Candida parapsilosis complex were differentiated using the HWP1 gene amplification and PCR-RFLP with NlaIII restriction enzyme, respectively. Results: Out of 75 blood culture specimens, 42 (84%) cases were positive for Candida spp. of whom 30 (71.42%) and 12 (28.57%) cases were female and male, respectively. Thirty-two (76%) candidemia were presented in pediatrics with 6 years up to 12 years, 10 (23.80%) in neonates of one month or less. In the present study, Candida parapsilosis (n =25; 59.52%) was the most prevalent isolated species followed by C. albicans (n =11; 26.19%), C. tropicalis (n =4; 9.52%), and Candida glabrata (n =2; 4.76%). Conclusions: According to potentially dangerous complications of bloodstream infection by Candida spp. in neonates and children, it is necessary to identify and eliminate the underlying conditions and risk factors of this disease.

Analysis of fungal bloodstream infection in intensive care units in the Meizhou region of China: species distribution and resistance and the risk factors for patient mortality

Background

Fungal bloodstream infections (FBI) among intensive care unit (ICU) patients are increasing. Our objective was to characterize the fungal pathogens that cause bloodstream infections and determine the epidemiology and risk factors for patient mortality among ICU patients in Meizhou, China.

Methods

Eighty-one ICU patients with FBI during their stays were included in the study conducted from January 2008 to December 2017. Blood cultures were performed and the antimicrobial susceptibility profiles of the resulting isolates were determined. Logistic multiple regression and ROC curve analysis were used to assess the risk factors for mortality among the cases.

Results

The prevalence of FBI in ICU patients was 0.38% (81/21,098) with a mortality rate of 36% (29/81). Ninety-eight strains of bloodstream-infecting fungi, mainly Candida spp., were identified from these patients. Candida albicans was most common (43%). Two strains of C. parapsilosis were no-sensitive to caspofungin, C. glabrata were less than 80% sensitive to azole drugs. Logistic multiple regression showed that age, serum albumin, APACHE II score, three or more underlying diseases, and length of stay in ICU were independent risk factors for mortality in FBI. ROC curve analysis showed that APACHE II scores > 19 and serum albumin ≤25 g/L were the best predictors of mortality.

Conclusion

Candida spp. predominated with high mortality rates among cases of FBI in ICU. Thus, clinical staff should enhance overall patient monitoring and concurrently monitor fungal susceptibility to reduce mortality rates.

Antifungal susceptibility of yeast bloodstream isolates collected during a 10-year period in Austria

BACKGROUND

Candida-associated infections put a significant burden on western healthcare systems. Development of (multi-)resistant fungi can become untreatable and threaten especially vulnerable target groups, such as the immunocompromised.

OBJECTIVES

We assessed antifungal susceptibility and explored possible influence factors of clinical Candida isolates collected from Austrian hospitals between 2007 and 2016.

METHODS

Thousand three hundred and sixty clinical Candida spp. isolated from blood cultures were subjected to antifungal susceptibility testing (AFST) in a liquid-handling aided continuous microdilution assay. We tested against fluconazole, voriconazole, posaconazole, itraconazole, isavuconazole, anidulafungin, caspofungin and micafungin according to EUCAST with additional recording of growth curves. We performed rigid quality control on each assay via growth curve assessment and included two standard reference strains. Minimal inhibitory concentrations (MIC) were quantified according to EUCAST guideline E.DEF 7.3.1, and susceptibility was evaluated using EUCAST clinical breakpoints.

RESULTS

The isolate collection consisted of Candida albicans (59%), C. glabrata (19%), C. parapsilosis (9%), C. tropicalis (5%) and C. krusei (3%) and few other Candida species and fungi (5%). During the observed time period, species abundance and antifungal resistance rates remained constant. Multi-resistance was rare and we found no single isolate which was resistant to both azoles and echinocandins. Within the antifungal resistance profile of our strain collection, we observed clusters along species boundaries.

CONCLUSIONS

Over the last decade, the distribution of Candida species and its level of antifungal resistance remained constant in Austria. Our data compare well with other European countries. Principal component analysis of the susceptibility profile of this collection revealed species-specific clusters and substantial intra-species variation, especially for C. glabrata.

An Azole-Resistant Candida parapsilosis Outbreak: Clonal Persistence in the Intensive Care Unit of a Brazilian Teaching Hospital

The incidence of candidemia by the Candida parapsilosis complex has increased considerably in recent decades, frequently related to use of indwelling intravascular catheters. The ability of this pathogen to colonize healthcare workers (HCW)' hands, and to form biofilm on medical devices has been associated with the occurrence of nosocomial outbreaks and high mortality rates. Fluconazole has been the leading antifungal drug for the treatment of invasive candidiasis in developing countries. However, azole-resistant C. parapsilosis isolates are emerging worldwide, including in Brazil. Few studies have correlated outbreak infections due to C. parapsilosis with virulence factors, such as biofilm production. We thus conducted a microbiological investigation of C. parapsilosis complex isolates from a Brazilian teaching hospital. Additionally, we identified a previously unrecognized outbreak caused by a persistent azole-resistant C. parapsilosis (sensu stricto) clone in the intensive care unit (ICU), correlating it with the main clinical data from the patients with invasive candidiasis. The molecular identification of the isolates was carried out by PCR-RFLP assay; antifungal susceptibility and biofilm formation were also evaluated. The genotyping of all C. parapsilosis (sensu stricto) was performed by microsatellite analysis and the presence of ERG11 mutations was assessed in the azole non-susceptible isolates. Fourteen C. parapsilosis (sensu stricto) isolates were recovered from patients with invasive candidiasis, eight being fluconazole and voriconazole-resistant, and two intermediate only to fluconazole (FLC). All non-susceptible isolates showed a similar pattern of biofilm formation with low biomass and metabolic activity. The A395T mutation in ERG11 was detected exclusively among the azole-resistant isolates. According to the microsatellite analysis, all azole non-susceptible isolates from the adult ICU were clustered together indicating the occurrence of an outbreak. Regarding clinical data, all patients infected by the clonal non-susceptible isolates and none of the patients infected by the susceptible isolates had been previously exposed to corticosteroids (p = 0.001), while the remaining characteristics showed no statistical significance. The current study revealed the persistence of an azole non-susceptible C. parapsilosis clone with low capacity to form biofilm over two years in the adult ICU. These results reinforce the need of epidemiological surveillance and monitoring antifungal susceptibility of C. parapsilosis isolates in hospital wards.

Risk factors and predictors of mortality of candidaemia among critically ill patients: role of antifungal prophylaxis in its development and in selection of non-albicans species

PURPOSE

The aim of the present study is to identify risk factors for development and predictors of mortality of candidaemia among critically ill patients.

METHODS

A 1:7 case-control study was conducted during a 4-year period (2012-2015) in a Greek Intensive Care Unit (ICU). Candidaemia was confirmed by positive blood cultures. All yeasts were identified using API 20C AUX System or Vitek 2 Advanced Expert System. Epidemiologic data were collected from the ICU computerized database and patients' chart reviews.

RESULTS

Fifty-three patients developed candidaemia with non-albicans species being the predominant ones (33 patients, 62.3%). Multivariate analysis found that prior emergency surgery, malignancy, hospitalization during summer months, prior septic shock by KPC-producing Klebsiella pneumoniae and number of antibiotics administered were independently associated with candidaemia, while, prior administration of azole was a protective factor. Non-albicans candidaemia was associated with number of antibiotics administered and prior administration of echinocandin. Mortality of 14 days was 28.3% (15 patients) and was associated with SOFA score upon infection onset and septic shock, while, appropriate empirical antifungal treatment was associated with better survival.

CONCLUSIONS

Prophylactic azole administration prevents development of candidaemia, while, echinocandin administration predisposes to non-albicans candidaemia. Empirical administration of an appropriate antifungal agent is associated with better survival.

[Update on invasive candidiasis in non-neutropenic critically ill adult patients]

Invasive candidiasis in non-neutropenic critically ill patients remains a challenge for clinicians due to its association with high morbidity and mortality rates, increased incidence, and health-care costs. It is well known that early diagnosis and treatment are associated with a better prognosis. For these reasons a thorough update has been performed in this setting focused on recent Spanish epidemiology, new predictive scores and microbiological tests such as mannan antigen, mannan antibodies, Candida albicans germ-tube antibodies or (1→3)-β-D-glucan detection, molecular techniques for the detection of fungal-specific DNA, advances in antifungal treatment and educational programs in Spain. An early diagnostic and therapeutic algorithm is proposed based on the combination of scores and microbiological test. The aim of this review is to provide physicians with the best information available in order to improve the prognosis of these patients.

Investigation of an unrecognized large-scale outbreak of Candida parapsilosis sensu stricto fungaemia in a tertiary-care hospital in China

A data analysis of yeast collections from the National China Hospital Invasive Fungal Surveillance Net (CHIF-NET) programme in 2013 revealed a sudden increase in the proportion of Candida parapsilosis complex isolates (n = 98) in one participating hospital (Hospital H). Out of 443 yeast isolates submitted to the CHIF-NET reference laboratory by Hospital H (2010–2014), 212 (47.9%) were identified as C. parapsilosis sensu stricto by sequencing analysis of the internal transcribed spacer region and D1/D2 domain of the 26S rRNA gene. Among the 212 C. parapsilosis sensu stricto isolates, 176 (83.0%) bloodstream-based isolates and 25 isolates from tip cultures of various vascular catheters from 25 patients with candidaemia, were subjected to microsatellite genotyping, and a phylogenetic relationship analysis was performed for 152 isolates. Among the 152 isolates, 45 genotypes (T01 to T45) were identified, and two prevalent genotypes (63.8%) were found: T15 (n = 74, 48.7%) and T16 (n = 23, 15.1%). These two main clones were confined mainly to three different wards of the hospital, and they persisted for 16–25 months and 12–13 months, respectively. The lack of proper coordination between the clinical microbiology laboratory and infection control staff as part of public health control resulted in the failure to timely identify an outbreak, which led to the wide and long-term dissemination of C. parapsilosis sensu stricto in Hospital H.

Development of fluconazole resistance in a series of Candida parapsilosis isolates from a persistent candidemia patient with prolonged antifungal therapy

Background

Candida parapsilosis was the most common species causing candidemia in the 2010 China Hospital Invasive Fungal Surveillance Net (CHIF-NET) database. Compared to Candida albicans, the description of azole resistance and mechanisms in C. parapsilosis is very limited. We report a patient with C. parapsilosis candidemia over several months, due to a probable intravascular source, who developed fluconazole resistance after prolonged treatment.

Case presentation

An 82 year-old male had a hospital admission of approximately 1.5 years duration. He was initially admitted with acute pancreatitis. Prior to succumbing to the illness, he developed candidemia and treated with three antifungal drugs for nearly 5 months, at suboptimal doses and without source control. Following treatment, 6 blood cultures were still positive for C. parapsilosis. The last 2 strains were resistant to fluconazole (MICs 32 μg/mL) and intermediate to voriconazole (MICs 0.5 μg/mL). Microsatellite multilocus analysis indicated that the 6 isolates from the patient belonged to a single genotype. The first 4 isolates were susceptible to fluconazole (MICs 2 μg/mL) and voriconazole (MICs 0.015-0.03 μg/mL), which were slightly higher than susceptible control strains from other patients. Overexpression of MDR1 genes were detected in the two resistant isolates, and this was associated with a homozygous mutation in MRR1 genes (T2957C /T2957C), with the amino acid exchange L986P.

Conclusions

This case corroborates that the resistant C. parapsilosis isolates can emerge in the setting of complicated infections and the extensive use of antifungal agents, emphasizing the need for standardizing and improving the antifungal treatment as well as source control in the treatment of infection diseases.

Candida Bloodstream Infections in Italy: Changing Epidemiology during 16 Years of Surveillance

Although considerable progress has been made in the management of patients with invasive fungal infections, Candida bloodstream infections are still widespread in hospital settings. Incidence rates vary geographically, often because of different patient populations. The aim of the present study was to describe the epidemiology of candidemia, to analyze the trend of species distribution, and to measure the in vitro susceptibility to antifungal drugs in a university Italian hospital from 1998 to 2013. The antifungal susceptibility for all Candida isolates was evaluated by broth microdilution assay (CLSI M27-A3 document). Of 394 episodes of candidemia, the average incidence was 3.06/10 000 admissions. C. albicans and non-albicans Candida species caused 44.2% and 55.8% of the episodes, respectively. C. parapsilosis (62.2%) was the most common non-albicans.   C. albicans predominated in almost all departments whereas C. parapsilosis was found in adult and paediatric oncohaematology units (34.8% and 77.6%, resp.). Overall, mortality occurred in 111 (28.2%) patients. Death occurred most often in intensive care units (47.1%) and specialist surgeries (43.7%). Most of the isolates were susceptible to antifungal drugs, but there was an upward trend for azole (P < 0.05). In conclusion, this study emphasizes the importance of monitoring local epidemiologic data and the diversity of patient groups affected.

Different scenarios for Candida parapsilosis fungaemia reveal high numbers of mixed C. parapsilosis and Candida orthopsilosis infections

Nosocomial fungal bloodstream infections (BSI) are increasing significantly in hospitalized patients and Candida parapsilosis has emerged as an important pathogen responsible for numerous outbreaks. The objective of this study was to evaluate C. parapsilosis sensu lato infection scenarios, regarding species distribution and strain relatedness. One hundred isolates of C. parapsilosis sensu lato derived from blood cultures and catheter tips were analysed by multiplex microsatellite typing and by sequencing D1/D2 regions of the ribosomal DNA. Our results indicate that 9.5 % of patients presented infections due to C. parapsilosis and Candida orthopsilosis, 57.1 % due to C. parapsilosis, 28.3 % due to C. orthopsilosis and 4.8 % due to Candida metapsilosis. Eighty per cent of the C. parapsilosis BSIs were due to a single strain that was also identified in the catheter, but in 10 % of the cases C. parasilosis was identified in the catheter but the BSI was due to C. orthopsilosis. There is a significant probability that C. parapsilosis isolates collected from the same patient at more than 3 months interval are of different strains (P = 0.0179). Moreover, several isolates were identified persistently in the same hospital, infecting six different patients. The incidence of polyfungal BSI infections with C. parapsilosis and C. orthopsilosis is reported herein for the first time, emphasizing the fact that the species identified in the catheter is not always responsible for the BSI, thus impacting the treatment strategy. The observation that strains can remain in the hospital environment for years highlights the possible existence of reservoirs and reinforces the need for accurate genotyping tools, such as the markers used for elucidating epidemiological associations and detecting outbreaks.

Comparative phenotypic analysis of the major fungal pathogens Candida parapsilosis and Candida albicans

Candida parapsilosis and Candida albicans are human fungal pathogens that belong to the CTG clade in the Saccharomycotina. In contrast to C. albicans, relatively little is known about the virulence properties of C. parapsilosis, a pathogen particularly associated with infections of premature neonates. We describe here the construction of C. parapsilosis strains carrying double allele deletions of 100 transcription factors, protein kinases and species-specific genes. Two independent deletions were constructed for each target gene. Growth in >40 conditions was tested, including carbon source, temperature, and the presence of antifungal drugs. The phenotypes were compared to C. albicans strains with deletions of orthologous transcription factors. We found that many phenotypes are shared between the two species, such as the role of Upc2 as a regulator of azole resistance, and of CAP1 in the oxidative stress response. Others are unique to one species. For example, Cph2 plays a role in the hypoxic response in C. parapsilosis but not in C. albicans. We found extensive divergence between the biofilm regulators of the two species. We identified seven transcription factors and one protein kinase that are required for biofilm development in C. parapsilosis. Only three (Efg1, Bcr1 and Ace2) have similar effects on C. albicans biofilms, whereas Cph2, Czf1, Gzf3 and Ume6 have major roles in C. parapsilosis only. Two transcription factors (Brg1 and Tec1) with well-characterized roles in biofilm formation in C. albicans do not have the same function in C. parapsilosis. We also compared the transcription profile of C. parapsilosis and C. albicans biofilms. Our analysis suggests the processes shared between the two species are predominantly metabolic, and that Cph2 and Bcr1 are major biofilm regulators in C. parapsilosis.

Candida species are among the most common causes of fungal infection worldwide. Infections can be both community-based and hospital-acquired, and are particularly associated with immunocompromised individuals. Candida albicans is the most commonly isolated species and is the best studied. However, other species are becoming of increasing concern. Candida parapsilosis causes outbreaks of infection in neonatal wards, and is one of the few Candida species that is transferred from the hands of healthcare workers. C. parapsilosis, like C. albicans, grows as biofilms (cell communities) on the surfaces of indwelling medical devices like feeding tubes. We describe here the construction of a set of tools that allow us to characterize the virulence properties of C. parapsilosis, and in particular its ability to grow as biofilms. We find that some of the regulatory mechanisms are shared with C. albicans, but others are unique to each species. Our tools, based on selectively deleting regulatory genes, will provide a major resource to the fungal research community.

Global trends in the distribution of Candida species causing candidemia

Only five species account for 92% of cases of candidemia (Candida albicans, C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei); however, their distribution varies in population-based studies conducted in different geographical areas. C. albicans is the most frequent species, but considerable differences are found between the number of cases caused by C. glabrata and C. parapsilosis. Studies from Northern Europe and the USA reported a high number of cases caused by C. glabrata, whereas studies from Spain and Brazil demonstrated a lower number of cases caused by C. glabrata and a higher number of cases attributed to C. parapsilosis. Globally, the frequency of C. albicans is decreasing, while that of C. glabrata and C. krusei is stable, and C. parapsilosis and C. tropicalis are increasing. Patient characteristics and prior antifungal therapy also have a considerable influence on the distribution and frequency of Candida spp., regardless of the geographical area. C. albicans is more frequent in patients aged up to 18 years, the frequency of C. parapsilosis decreases with age, and C. glabrata is more common in the elderly. Finally, the presence of horizontal transmission of Candida spp. isolates (reported mainly in patients from the adult medical and post-surgical ICU, patients from oncology-haematology units, and neonates) can affect species distribution.

Canadian clinical practice guidelines for invasive candidiasis in adults

Candidemia and invasive candidiasis (C/IC) are life-threatening opportunistic infections that add excess morbidity, mortality and cost to the management of patients with a range of potentially curable underlying conditions. The Association of Medical Microbiology and Infectious Disease Canada developed evidence-based guidelines for the approach to the diagnosis and management of these infections in the ever-increasing population of at-risk adult patients in the health care system. Over the past few years, a new and broader understanding of the epidemiology and pathogenesis of C/IC has emerged and has been coupled with the availability of new antifungal agents and defined strategies for targeting groups at risk including, but not limited to, acute leukemia patients, hematopoietic stem cell transplants and solid organ transplants, and critical care unit patients. Accordingly, these guidelines have focused on patients at risk for C/IC, and on approaches of prevention, early therapy for suspected but unproven infection, and targeted therapy for probable and proven infection.

Conserved and divergent roles of Bcr1 and CFEM proteins in Candida parapsilosis and Candida albicans

Candida parapsilosis is a pathogenic fungus that is major cause of hospital-acquired infection, predominantly due to growth as biofilms on indwelling medical devices. It is related to Candida albicans, which remains the most common cause of candidiasis disease in humans. The transcription factor Bcr1 is an important regulator of biofilm formation in vitro in both C. parapsilosis and C. albicans. We show here that C. parapsilosis Bcr1 is required for in vivo biofilm development in a rat catheter model, like C. albicans. By comparing the transcription profiles of a bcr1 deletion in both species we found that regulation of expression of the CFEM family is conserved. In C. albicans, three of the five CFEM cell wall proteins (Rbt5, Pga7 and Csa1) are associated with both biofilm formation and acquisition of iron from heme, which is an important virulence characteristic. In C. parapsilosis, the CFEM family has undergone an expansion to 7 members. Expression of three genes (CFEM2, CFEM3, and CFEM6) is dependent on Bcr1, and is induced in low iron conditions. All three are involved in the acquisition of iron from heme. However, deletion of the three CFEM genes has no effect on biofilm formation in C. parapsilosis. Our data suggest that the role of the CFEM family in iron acquisition is conserved between C. albicans and C. parapsilosis, but their role in biofilm formation is not.

Isolates from hospital environments are the most virulent of the Candida parapsilosis complex

Background

Candida parapsilosis is frequently isolated from hospital environments, like air and surfaces, and causes serious nosocomial infections. Molecular studies provided evidence of great genetic diversity within the C. parapsilosis species complex but, despite their growing importance as pathogens, little is known about their potential to cause disease, particularly their interactions with phagocytes. In this study, clinical and environmental C. parapsilosis isolates, and strains of the related species C. orthopsilosis and C. metapsilosis were assayed for their ability to induce macrophage cytotocixity and secretion of the pro-inflammatory cytokine TNF-α, to produce pseudo-hyphae and to secrete hydrolytic enzymes.

Results

Environmental C. parapsilosis isolates caused a statistically significant (p = 0.0002) higher cell damage compared with the clinical strains, while C. orthopsilosis and C. metapsilosis were less cytotoxic. On the other hand, clinical isolates induced a higher TNF-α production compared with environmental strains (p < 0.0001). Whereas the amount of TNF-α produced in response to C. orthopsilosis strains was similar to the obtained with C. parapsilosis environmental isolates, it was lower for C. metapsilosis strains. No correlation between pseudo-hyphae formation or proteolytic enzymes secretion and macrophage death was detected (p > 0.05). However, a positive correlation between pseudo-hyphae formation and TNF-α secretion was observed (p = 0.0119).

Conclusions

We show that environmental C. parapsilosis strains are more resistant to phagocytic host defences than bloodstream isolates, being potentially more deleterious in the course of infection than strains from a clinical source. Thus, active environmental surveillance and application of strict cleaning procedures should be implemented in order to prevent cross-infection and hospital outbreaks.

Candida parapsilosis: a review of its epidemiology, pathogenesis, clinical aspects, typing and antimicrobial susceptibility

The Candida parapsilosis family has emerged as a major opportunistic and nosocomial pathogen. It causes multifaceted pathology in immuno-compromised and normal hosts, notably low birth weight neonates. Its emergence may relate to an ability to colonize the skin, proliferate in glucose-containing solutions, and adhere to plastic. When clusters appear, determination of genetic relatedness among strains and identification of a common source are important. Its virulence appears associated with a capacity to produce biofilm and production of phospholipase and aspartyl protease. Further investigations of the host-pathogen interactions are needed. This review summarizes basic science, clinical and experimental information about C. parapsilosis.

Nosocomial infections in patients with cancer

Nosocomial infections are those that become evident 48 h or more after a patient is admitted for treatment in a hospital or in another health-care setting. These infections cause substantial morbidity and mortality in patients who are immunosuppressed. Over the past few decades, understanding of host vulnerability has improved and more rigorous management and infection-control practices have been adopted for treating susceptible populations. Despite efforts, outbreaks continue to occur. In this Review, we outline current knowledge of the incidence and microbiology of various nosocomial infections in patients with cancer-a large, immunosuppressed population.

Candidemia and candiduria in critically ill patients admitted to intensive care units in France: incidence, molecular diversity, management and outcome

OBJECTIVE

To determine the concomitant incidence, molecular diversity, management and outcome of nosocomial candidemia and candiduria in intensive care unit (ICU) patients in France.

DESIGN

A 1-year prospective observational study in 24 adult ICUs.

PATIENTS

Two hundred and sixty-two patients with nosocomial candidemia and/or candiduria.

MEASUREMENTS AND RESULTS

Blood and urine samples were collected when signs of sepsis were present. Antifungal susceptibility of Candida strains was determined; in addition, all blood and 72% of urine C. albicans isolates were analyzed by using multi-locus sequence type (MLST). The mean incidences of candidemia and candiduria were 6.7 and 27.4/1000 admissions, respectively. Eight percent of candiduric patients developed candidemia with the same species. The mean interval between ICU admission and candidemia was 19.0 +/- 2.9 days, and 17.2 +/- 1.1 days for candiduria. C. albicans and C. glabrata were isolated in 54.2% and 17% of blood and 66.5% and 21.6% of urine Candida-positive cultures, respectively. Fluconazole was the most frequently prescribed agent. In all candidemic patients, the prescribed curative antifungal agent was active in vitro against the responsible identified strain. Crude ICU mortality was 61.8% for candidemic and 31.3% for candiduric patients. Seventy-five percent of the patients were infected with a unique C. albicans strain; cross-transmission between seven patients was suggested in one hospital.

CONCLUSIONS

Candidemia is late-onset ICU-acquired infection associated with high mortality. No difference in susceptibility and genetic background were found between blood and urine strains of Candida species.

Development of a gene knockout system in Candida parapsilosis reveals a conserved role for BCR1 in biofilm formation

Candida parapsilosis is an important cause of candidiasis, yet few molecular tools are available. We adapted a recyclable nourseothricin resistance marker gene (SAT1) originally developed for use with C. albicans in order to generate gene knockouts from C. parapsilosis. We first replaced the promoters driving expression of the FLP recombinase and the SAT1 genes with the equivalent sequences from C. parapsilosis. We then used the cassette to generate a homozygous knockout of C. parapsilosis URA3. The ura3 knockouts have altered colony morphologies. We also knocked out both alleles of an ortholog of BCR1, a gene encoding a transcription factor known to be required for biofilm development in C. albicans. We show that C. parapsilosis BCR1 is necessary for biofilm development in C. parapsilosis and for expression of the cell wall protein encoded by RBT1. Our results suggest that there are significant similarities in the regulation of biofilms between the two species, despite the fact that C. parapsilosis does not generate true hyphae and that BCR1 regulates the expression of many hypha-specific adhesins in C. albicans.

Epidemiology, risk factors, and prognosis of Candida parapsilosis bloodstream infections: case-control population-based surveillance study of patients in Barcelona, Spain, from 2002 to 2003

Candida parapsilosis has emerged as an important yeast species causing fungemia. We describe the incidence and epidemiology of C. parapsilosis fungemia. Data from active population-based surveillance in Barcelona, Spain, from January 2002 to December 2003 were analyzed. We focused on 78 episodes of C. parapsilosis fungemia, and we compared them with 175 Candida albicans controls. C. parapsilosis accounted for 23% of all fungemias. The annual incidences were 1 episode per 10(5) patients, 1.2 episodes per 10(4) discharges, and 1.7 episodes per 10(5) patient days. All isolates but one (99%) were fluconazole susceptible. Seventy-two isolates (92%) were inpatient candidemias. Forty-two episodes (51%) were considered catheter-related fungemia, 35 (45%) were considered primary fungemia, and 3 (4%) were considered secondary fungemia. Risk factors for candidemia were vascular catheterization (97%), prior antibiotic therapy (91%), parenteral nutrition (54%), prior surgery (46%), prior immunosuppressive therapy (38%), malignancy (27%), prior antifungal infection (26%), transplant recipient (16%), neutropenia (12%), and prior colonization (11%). Multivariate analysis of the differential characteristics showed that the factors that independently predicted the presence of C. parapsilosis fungemia were neonate patients (odds ratio [OR], 7.5; 95% confidence interval [CI], 2.1 to 26.8; P = 0.002), transplant recipients (OR, 9.2; 95% CI, 1.9 to 43.3; P = 0.005), patients with a history of prior antifungal therapy (OR, 5.4; 95% CI, 1.8 to 15.9; P = 0.002), and patients who received parenteral nutrition (OR, 2.2; 95% CI, 1.09 to 4.6; P = 0.028). The overall mortality rate was lower than that associated with C. albicans candidemia (23% versus 43%; P < 0.01). In summary, C. parapsilosis was responsible for 23% of all candidemias and was more frequent in neonates, in transplant recipients, and in patients who received parenteral nutrition or previous antifungal therapy, mainly fluconazole. The mortality rate was lower than that associated with C. albicans fungemia.

Candida biofilm: a well-designed protected environment

Biofilms are colonies of microbial cells encased in a self-produced organic polymeric matrix and represent a common mode of microbial growth. Microbes growing as biofilm are highly resistant to commonly used antimicrobial drugs. Recently, microbial biofilms have gained prominence because of the increase in infections related to indwelling medical devices (IMD). Candida albicans, the pathogenic fungus which is a major cause of morbidity and mortality in blood stream infections, is the most common fungal pathogen isolated from patients with IMD-associated infections. Biofilm formation by Candida species is believed to contribute to invasiveness of these fungal species. We discuss experimental methods used to study fungal biofilms as well as the biology of biofilm formation by clinically relevant Candida species. Recent advances that are discussed in this review include the role of specific, differentially expressed genes and proteins, quorum sensing molecule in C. albicans biofilms, and the correlation between biofilm formation and fungal pathogenesis.

Could hospital patients' hands constitute a missing link?

The relationship between contamination of patients' hands and transmission of healthcare-associated infection has received only limited attention, but may represent a previously overlooked but potentially significant link in the chain of infection. This paper aims critically to review the literature to determine whether this possible epidemiological relationship is worthy of further consideration. Studies that have investigated the microbiology or hand hygiene behaviours of patients and other groups are examined to establish their limitations and implications for future practice and research. Examples of healthcare-associated infections where improving patient hand hygiene may have a favourable impact on transmission, and how this might be achieved within the context of current UK health service initiatives, are discussed. It is recommended that systematic studies of the role of patients' hands in the chain of hospital infection should be undertaken.