Fungal Infections in the ICU

Current Utilization of Antifungal Agents for Intra-abdominal Infections Categorized by Patient Risk Factors During Surgical Procedures: A Literature Review

The high morbidity and mortality rates associated with invasive fungal infections have led to the overutilization of empiric antifungal therapies. With increasing antibiotic resistance, the careful consideration of prophylactic or empiric antifungal use is critical. The purpose of this review is to evaluate the available literature regarding the current practice of utilizing antifungal agents for intra-abdominal infections based on specific surgical procedures and patient risk factors. Relevant articles were identified through a comprehensive literature search of several databases using the keywords antifungal agents, postoperative period, preoperative care, surgical procedures, and intra-abdominal infections. Only articles that evaluated the use of empiric antifungals for suspected or confirmed intra-abdominal infections and surgical procedures were included in this review. Based on the available literature, antifungal prophylaxis is appropriate in patients who meet the criteria for high-risk invasive candidiasis, kidney or liver transplant recipients, severely-immunocompromised patients with perforated peptic ulcer, peritonitis, and patients on peritoneal dialysis who are failing on a therapeutic antibiotic regimen. We acknowledge that the evidence for using antifungal therapy empirically for all surgical procedures is lacking, and the following review is based on available literature and current guidelines.

Invasive Pulmonary Aspergillosis: Not Only a Disease Affecting Immunosuppressed Patients

Fungal infections have become a common threat in Intensive Care Units (ICU). The epidemiology of invasive fungal diseases (IFD) has been extensively studied in patients severely immunosuppressed over the last 20-30 years, however, the type of patients that have been admitted to hospitals in the last decade has made the healthcare system and ICU a different setting with more vulnerable hosts. Patients admitted to an ICU tend to have older age and higher severity of disease. Moreover, the number of patients being treated in ICU are often immunosuppressed as a result of the widespread use of immunomodulatory agents, such as corticosteroids, chemotherapy, and biological agents. The development of Invasive Pulmonary aspergillosis (IPA) reflects a different clinical trajectory to affected patients. The increasing use of corticosteroids would probably explain the higher incidence of IPA especially in critically ill patients. In refractory septic shock, severe community-acquired pneumonia (SCAP), and acute respiratory distress syndrome (ARDS), the use of corticosteroids has re-emerged in order to decrease unacceptably high mortality rates associated with these clinical conditions. It is also pertinent to note that different reports have used different diagnosis criteria, and this might explain the different incidence rates. Another layer of complexity to better understand current IPA data is related to more aggressive acquisition of samples through invasive respiratory examinations.

Growth of Aspergillus fumigatus in Biofilms in Comparison to Candida albicans

Biofilm formation during infections with the opportunistic pathogen Aspergillus fumigatus can be very problematic in clinical settings, since it provides the fungal cells with a protective environment. Resistance against drug treatments, immune recognition as well as adaptation to the host environment allows fungal survival in the host. The exact molecular mechanisms behind most processes in the formation of biofilms are unclear. In general, the formation of biofilms can be categorized roughly in a few stages; adhesion, conidial germination and development of hyphae, biofilm maturation and cell dispersion. Fungi in biofilms can adapt to the in-host environment. These adaptations can occur on a level of phenotypic plasticity via gene regulation. However, also more substantial genetic changes of the genome can result in increased resistance and adaptation in the host, enhancing the survival chances of fungi in biofilms. Most research has focused on the development of biofilms. However, to tackle developing microbial resistance and adaptation in biofilms, more insight in mechanisms behind genetic adaptations is required to predict which defense mechanisms can be expected. This can be helpful in the development of novel and more targeted antifungal treatments to combat fungal infections.

Epidemiology of Candida isolates from Intensive Care Units in Colombia from 2010 to 2013

BACKGROUND

The frequency of Candida isolates as a cause of hospital infections has risen in recent years, leading to high rates of morbidity and mortality. The knowledge of the epidemiology of those hospital acquired fungal infections is essential to implement an adequate antifungal therapy.

AIMS

To describe the epidemiology of Candida infections in Intensive Care Units (ICUs) from a surveillance network in Colombia.

METHODS

Information was collected from the microbiology laboratories of 20 tertiary healthcare institutions from 10 Colombian cities using the Whonet® software version 5.6. A general descriptive analysis of Candida species and susceptibility profiles focusing on fluconazole and voriconazole was completed between 2010 and 2013, including a sub-analysis of healthcare associated infections (HAIs) during the last year.

RESULTS

Candida isolates made up 94.5% of the 2680 fungal isolates considered, with similar proportions for Candida albicans and non-C. albicans Candida species (48.3% and 51.7%, respectively). Among the latter, Candida tropicalis (38.6%) and Candida parapsilosis (28.5%) were the most frequent species. Of note, among the blood isolates C. albicans was not the main species. Most of the species isolated were susceptible to fluconazole and voriconazole. From the HAIs reported, 25.5% were caused by Candida; central line-associated bloodstream infection was the most common HAI (58.8%). There were no statistically significant differences regarding length of hospital stay and device days among HAIs.

CONCLUSIONS

In ICUs of Colombia, non-C. albicans Candida species are as frequent as C. albicans, except in blood samples where non-C. albicans Candida isolates predominate. Further studies are needed to evaluate Candida associated risk factors and to determine its clinical impact.

Invasive aspergillosis in intensive care unit patients in Iran

We assessed the intensive care unit (ICU) patients for Invasive aspergillosis (IA) with culture and non-culture based diagnostic methods from Iran. Thirty-six ICU patients with underlying predisposing conditions for IA were enrolled in the study. Sixty eight Bronchoalveolar lavage (BAL) samples were collected by bronchoscope twice a weekly. BAL samples were analyzed by microscopic examination, fungal culture and galactomannan (GM) detection. The Platelia Aspergillus GM EIA was used to quantify GM indices. Samples with a BAL GM index > or = 1 were considered as positive for GM. Patients were classified as having probable or possible IA. Out of 36 suspected patients to IA, 36.1% of cases showed IA which were categorized as: 4 cases of possible IA and 9 of probable IA. 76.2% of BAL samples were positive for GM. From 13 patients with IA, 11 (84.6%) had at least one positive BAL GM index. Of these patients, 9 (81.8%) showed probable IA. The main underlying predisposing conditions were neutropenia (53.8%) and COPD (30.8%). Our study has indicated that COPD must be considered as one of the main predisposing condition for occurrence of aspergillosis in ICU patients. Our data have also revealed that GM detection in BAL samples play a significant role to IA diagnosis.

Targeting UDP-galactopyranose mutases from eukaryotic human pathogens

UDP-Galactopyranose mutase (UGM) is a unique flavin-dependent enzyme that catalyzes the conversion of UDP-galactopyranose(UDP-Galp) to UDP-galactofuranose (UDP-Galf). The product of this reaction is the precursor to Galf, a major component of the cell wall and of cell surface glycoproteins and glycolipids in many eukaryotic and prokaryotic human pathogens. The function of UGM is important in the virulence of fungi, parasites, and bacteria. Its role in virulence and its absence in humans suggest that UGM is an ideal drug target. Significant structural and mechanistic information has been accumulated on the prokaryotic UGMs; however, in the past few years the research interest has shifted to UGMs from eukaryotic human pathogens such as fungi and protozoan parasites. It has become clear that UGMs from prokaryotic and eukaryotic organisms have different structural and mechanistic features. The amino acid sequence identity between these two classes of enzymes is low, resulting in differences in oligomeric states, substrate binding, active site flexibility, and interaction with redox partners. However, the unique role of the flavin cofactor in catalysis is conserved among this enzyme family. In this review, recent findings on eukaryotic UGMs are discussed and presented in comparison with prokaryotic UGMs.

Invasive Aspergillus infections in hospitalized patients with chronic lung disease

BACKGROUND

Although invasive pulmonary aspergillosis (IPA) is more prevalent in immunocompromised patients, critical care clinicians need to be aware of the occurrence of IPA in the nontraditional host, such as a patient with chronic lung disease. The purpose of this study was to describe the IPA patient with chronic lung disease and compare the data with that of immunocompromised patients.

METHODS

The records of 351 patients with Aspergillus were evaluated in this single-center, retrospective study for evidence and outcomes of IPA. The outcomes of 57 patients with chronic lung disease and 56 immunocompromised patients were compared. Patients with chronic lung disease were defined by one of the following descriptive terms: emphysema, asthma, idiopathic lung disease, bronchitis, bronchiectasis, sarcoid, or pulmonary leukostasis.

RESULTS

Baseline demographics were similar between the two groups. Patients with chronic lung disease were primarily defined by emphysema (61%) and asthma (18%), and immunocompromised patients primarily had malignancies (27%) and bone marrow transplants (14%). A higher proportion of patients with chronic lung disease had a diagnosis of IPA by bronchoalveolar lavage versus the immunocompromised group (P < 0.03). The major risk factors for IPA were found to be steroid use in the chronic lung disease group and neutropenia and prior surgical procedures in the immunocompromised group. Overall, 53% and 69% of chronic lung disease and immunocompromised patients were cured (P = 0.14); 55% of chronic lung patients and 47% of immunocompromised patients survived one month (P = 0.75).

CONCLUSION

Nontraditional patients with IPA, such as those with chronic lung disease, have outcomes and mortality similar to that in the more traditional immunocompromised population.

Evaluation of intravenous voriconazole in patients with compromised renal function

Background

Incorporation of the solubilizing excipient, sulfobutylether-β-cyclodextrin (SBECD), in the intravenous (IV) formulation of voriconazole has resulted in the recommendation that this formulation be used with caution in patients with creatinine clearances (Cl_cr) < 50 mL/min. This study evaluated the safety of IV voriconazole compared with two other IV antifungals not containing SBECD in patients with compromised renal function.

Methods

A total of 128 patients aged 11–93 years who had a baseline Cl_cr < 50 mL/min between January 1, 2007 and December 31, 2010 were identified from a database of a university-affiliated inpatient healthcare system; of these, 55 patients received caspofungin, 54 patients received fluconazole, and 19 patients received voriconazole. Changes in serum creatinine (S_cr) and Cl_cr levels while on therapy were compared with baseline values and between groups.

Results

The groups had similar characteristics apart from the larger proportion of females that received fluconazole. Baseline S_cr was higher in those receiving caspofungin, but maximal increases of S_cr and decreases in Cl_cr were greatest for the fluconazole group. Acute kidney injury (AKI), assessed by RIFLE criteria, was more frequent in the fluconazole vs. the caspofungin group (p < 0.01); incidence of AKI in the voriconazole group was not significantly different than found in the other two groups. The infecting organism was a predictor of AKI and formulation with SBECD was not.

Conclusions

Treatment of fungal infections in patients with compromised renal function with an SBECD-containing antifungal agent was not associated with AKI in clinical practice. Since the infecting organism was associated with AKI, decision on which antifungal to use should be determined by susceptibilities to the organism and not the incorporation of SBECD in the IV formulation.

Frequency of decreased susceptibility and resistance to echinocandins among fluconazole-resistant bloodstream isolates of Candida glabrata

The echinocandin class of antifungal agents is considered to be the first-line treatment of bloodstream infections (BSI) due to Candida glabrata. Recent reports of BSI due to strains of C. glabrata resistant to both fluconazole and the echinocandins are of concern and prompted us to review the experience of two large surveillance programs, the SENTRY Antimicrobial Surveillance Program for the years 2006 through 2010 and the Centers for Disease Control and Prevention population-based surveillance conducted in 2008 to 2010. The in vitro susceptibilities of 1,669 BSI isolates of C. glabrata to fluconazole, voriconazole, anidulafungin, caspofungin, and micafungin were determined by CLSI broth microdilution methods. Fluconazole MICs of ≥64 μg/ml were considered resistant. Strains for which anidulafungin and caspofungin MICs were ≥0.5 μg/ml and for which micafungin MICs were ≥0.25 μg/ml were considered resistant. A total of 162 isolates (9.7%) were resistant to fluconazole, of which 98.8% were nonsusceptible to voriconazole (MIC > 0.5 μg/ml) and 9.3%, 9.3%, and 8.0% were resistant to anidulafungin, caspofungin, and micafungin, respectively. There were 18 fluconazole-resistant isolates that were resistant to one or more of the echinocandins (11.1% of all fluconazole-resistant isolates), all of which contained an acquired mutation in fks1 or fks2. By comparison, there were no echinocandin-resistant strains detected among 110 fluconazole-resistant isolates of C. glabrata tested in 2001 to 2004. These data document the broad emergence of coresistance over time to both azoles and echinocandins in clinical isolates of C. glabrata.

Aspergillus biofilms: clinical and industrial significance

The biofilm phenotype is an increasingly important concept in mycological research. Recently, there has been a developing interest in whether Aspergillus species are truly able to form biofilms or not. Industrial mycologists have long been aware of biofilms and their benefit in fermentation processes, whereas clinically their role is uncertain. This review provides an update on the impact that Aspergillus biofilms have medically and industrially, and will discuss biofilm development, and our current understanding of its molecular basis. The role of exopolymeric substance and how this substance relates to antimicrobial recalcitrance will also be discussed.

Update on invasive mycoses by filamentous fungi in critically ill patients

The present article is an update of the literature on invasive fungal infections caused by filamentous fungi in critically ill patients. A multidisciplinary group of Spanish physicians with an interest in these infections organized a joint session and selected the most important papers produced lately in the field. Each article was analyzed and discussed by one of the members of the panel. Studies from the fields of causative microorganisms, epidemiology, and diagnosis are discussed; including the assessment of different strategies for the early identification and treatment of patients at risk of fungal infections by filamentous fungi in the intensive care unit setting.

Management of fungal infections in the intensive care unit: a survey of UK practice

BACKGROUND

Candida species are a common cause of nosocomial bloodstream infection. Such infections commonly affect patients in the intensive care unit (ICU) and carry a high mortality. There are published guidelines for the management of fungal infections, but there are no data on the usual management of invasive Candida infections in UK ICUs.

METHODS

An electronic survey was sent by email to a representative clinician in 236 ICUs, over 90% of units in the UK. Questions related to the institution of empirical therapy and to the management of proven candidaemia.

RESULTS

There were 72 responses. A minority of units follow a policy regarding the management of these infections but the involvement of microbiologists is usual. Empirical therapy is used in 85.9% of units, often for patients perceived to be at high risk. Fluconazole is the most commonly used antifungal agent, both for empirical therapy and for the treatment of proven candidaemia. For candidaemic patients, 73.9% of ICUs frequently or always remove central venous catheters within 48 h, while 15.1% frequently or always arrange ophthalmology review.

CONCLUSIONS

Management of fungal infections is relatively consistent among responding units. However, recent developments in the field have not yet been incorporated into standard practice. Adherence to published guidelines could be improved, potentially reducing morbidity and mortality from these common infections.

IL-23 and IL-17A, but not IL-12 and IL-22, are required for optimal skin host defense against Candida albicans

IL-23 and Th17 cells play important roles in host defense against systemic infections with extracellular bacteria and fungi, although their roles in immunity against localized skin infections are less well defined. Here, the contributions of IL-23 and Th17 cytokines in host defense against cutaneous Candida albicans infection were evaluated. Mice deficient in IL-23 or IL-17A demonstrated delayed healing and decreased IL-17A production after skin infection with C. albicans compared with wild-type mice or mice deficient in IL-12 or IL-22. Histologic examination revealed epidermal hyperplasia overlying infected dermis four days postinoculation in wild-type mice. In IL-23-deficient mice, fungal burden was greater in skin, neither IL-17A nor IL-22 mRNAs were expressed postinfection, and these mice demonstrated only minimal epidermal hyperplasia. Exogenous recombinant IL-17A injected at the site of skin infection promoted more rapid healing of candidiasis in both wild-type mice and mice deficient in IL-23 and IL-12. Taken together, these results demonstrate that IL-23 and IL-17A, but not IL-12 and IL-22, are required for optimal host defense against cutaneous candidiasis. In addition, recombinant IL-17A may serve as a potential therapy to enhance healing in individuals with chronic cutaneous candidiasis.

Risk factors and outcomes of fungal ventricular-assist device infections

BACKGROUND

Infection is a common complication of ventricular-assist devices (VADs) and is associated with rehospitalization, thromboembolic events, VAD malfunction, delay in heart transplantation, and a high mortality rate. The objectives of this study were to investigate the frequency of fungal VAD infections and assess various risk factors and their effects on mortality as compared with bacterial VAD infections.

METHODS

We conducted a retrospective chart review of patients with infected VADs at a single tertiary care center. The frequency, risk factors, and outcomes of fungal versus bacterial VAD infections were compared.

RESULTS

Of the 300 patients who received a VAD, 108 (36%) developed VAD infection, including 85 bacterial and 23 fungal infections. Most common bacterial causes of infection were Staphylococcus aureus, coagulase-negative staphylococci, enterococci, and Pseudomonas aeuruginosa. The most common fungal etiologic agent was Candida albicans. Only the use of total parenteral nutrition was associated with the development of a fungal VAD infection in multivariate analysis (odds ratio, 6.95; 95% confidence interval, 1.71-28.16; P=.007). Patients who experienced fungal VAD infection were less likely to be cured (17.4% vs 56.3%; P=.001) and had greater mortality (91% vs 61%; P=.006), compared with those who experienced bacterial VAD infection.

CONCLUSIONS

Fungi were responsible for approximately one-fifth of VAD infections and were associated with a mortality rate of 91%. Restriction of total parenteral nutrition use is essential in decreasing the rate of fungal VAD infection. Trials are needed for investigating the use of echinocandins or lipid formulations of amphotericin B for prevention and/or treatment of fungal VAD infection.

Respiratory Infections

Until recently, conventional culture techniques and immunofluorecence assays were considered the gold standard for the detection of respiratory viruses, even though results are mostly available too late or lacked specificity and sensitivity. These methods are now widely replaced with appropriate DNA- and RNA-based amplification techniques, in particular real time PCR amplification, for the detection of an extended number of agents responsible for acute respiratory infections. Real-time PCR offers rapid results, efficiencies in work flow and a reduced risk of false positive results due to contamination. As a result, better patient management or reduction of unnecessary antibiotic administration will be possible leading to enhanced efficiencies in health care. In applying molecular methods to diagnostic use, the laboratory can optimise its diagnostic strategy by applying a combination of real-time amplification tests for respiratory viruses and the non-viral respiratory bacterial pathogens. However this must be done within a context of resource availability, technical expertise available and clinical utility. It seems certain that molecular microbiology will continue to develop, leading to further applications in diagnostic technology, thereby improving our understanding of disease processes and enhancing our knowledge of the pathogens responsible.