Candida colonization in mechanically ventilated patients

Critically ill patients with COVID-19 show lung fungal dysbiosis with reduced microbial diversity in Candida spp colonized patients

Background

The COVID-19 pandemic has intensified interest in how the infection affects the lung microbiome of critically ill patients and how it contributes to acute respiratory distress syndrome (ARDS). We aimed to characterize the lower respiratory tract mycobiome of critically ill patients with COVID-19 in comparison to patients without COVID-19.

Methods

We performed an internal transcribed spacer 2 (ITS2) profiling with the Illumina MiSeq platform on 26 respiratory specimens from patients with COVID-19 as well as from 26 patients with non–COVID-19 pneumonia.

Results

Patients with COVID-19 were more likely to be colonized with Candida spp. ARDS was associated with lung dysbiosis characterized by a shift to Candida species colonization and a decrease of fungal diversity. We also observed higher bacterial phylogenetic distance among taxa in colonized patients with COVID-19. In patients with COVID-19 not colonized with Candida spp., ITS2 amplicon sequencing revealed an increase of Ascomycota unassigned spp. and 1 Aspergillus spp.–positive specimen. In addition, we found that corticosteroid therapy was frequently associated with positive Galactomannan cell wall component of Aspergillus spp. among patients with COVID-19.

Conclusion

Our study underpins that ARDS in patients with COVID-19 is associated with lung dysbiosis and that an increased density of Ascomycota unassigned spp. is present in patients not colonized with Candida spp.

Host factors and clinical outcomes of Candida colonization in critically ill patients

This study aimed to describe factors and outcomes associated with Candida colonization of critically ill patients. This was a cross-sectional study conducted over 2 weeks in the intensive care unit (ICU) of a tertiary care hospital at the Texas Medical Center, Houston, TX. All Candida samples were prospectively collected with demographic and clinical data collected retrospectively. We examined 48 patients, 32 (67%) were colonized with Candida spp; 25 (52.1%) patients were isolated with Candida albicans and 18 (37.5%) were isolated with a non-albicans species, mostly commonly Candida glabrata. A multivariate analysis identified proton pump inhibitor administration at admission to ICU [odds ratio 5.66; 95% confidence interval 1.12-28.5] as associated with colonization. Patients colonized with Candida had a significantly longer length of ICU and hospital stays (7.6 ± 6.6 vs. 4.2 ± 2.6 days, P = 0.01 and 14.9 ± 12.9 vs. 7.5 ± 6.7 days, P = 0.02, respectively). Clonality testing between C. albicans and C. glabrata strains identified indistinguishable strains among the patient cohort. These data provide additional information on Candida colonization in critically ill patients.

Risk factors of Candida colonization in the oropharynx of patients admitted to an intensive care unit

OBJECTIVES

Candida colonization is an important precursor for candidiasis. However, there is little information about its risk factors in critically ill patients. We aimed to identify risk factors for oropharyngeal Candida colonization in critically ill patients.

PATIENTS, MATERIALS AND METHODS

This is a prospective observational study of 110 patients admitted to a medical intensive care unit (MICU). Oropharyngeal swabs were obtained on day one and day four. Characteristics of patients colonized with Candida species at admission or not colonized were compared. In addition, patients becoming colonized during their ICU stay were compared to patients who did not.

RESULTS

Independent risk factors for a positive Candida sample at the time of admission were: a history of proton pump inhibitor (PPI) use before admission (OR: 5.24, 95% CI: 1.36-20.19), the presence of diabetes mellitus (OR: 2.84, 95%CI: 1.02-7.92) and a lower BMI (OR: 0.9, 95% CI: 0.84-0.97). Chronic kidney disease was associated with a decreased frequency of Candida colonization (OR: 0.26, 95% CI: 0.01-0.46). No independent risk factors could be identified for patients who gained Candida during their ICU hospitalization. Patients with Candida colonization frequently had abnormal oral bacterial flora.

CONCLUSIONS

Diabetes mellitus, PPI use and a lower BMI are risk factors for Candida colonization in critically ill patients being admitted to the MICU.

Time-related increase of staphylococci, Enterobacteriaceae and yeasts in the oral cavities of comatose patients

BACKGROUND/PURPOSE

The composition of oral microbiota in comatose patients remains uncertain. Some pulmonary pathogens may be found in dental biofilms or as part of the saliva microbiota. It is supposed that some pneumopathogenic microorganisms may overgrow in the mouths of comatose patients and spread to their lungs.

METHODS

The oral colonization dynamics of staphylococci, Enterobacteriaceae and yeasts in nine comatose patients (group 1), and in 12 conscious patients that brushed their teeth at least twice a day (group 2) was evaluated. Both groups were followed up for 7 days after hospitalization. Daily samples of saliva were obtained, dispersed and plated on selective culture media and colony forming units of each microbial group were obtained.

RESULTS

For patients in group 1, the counts of total viable bacteria, staphylococci, Enterobacteriaceae and yeasts progressively increased in a time-dependant manner. For the conscious patients of group 2, there was no increase.

CONCLUSION

It would appear that concomitant consciousness and brushing teeth are determinants in controlling the selected pneumopathogen counts in resting saliva. The increase in microbial counts in comatose patients is understandable because these microorganisms could spread to the lungs.

Viral colonization in intubated patients: initial pathogen pattern and follow-up

INTRODUCTION

Colonization of the lower respiratory tract is an independent risk factor for ventilator-associated pneumonia. Little is known about the frequency of viral colonization on intubation and during mechanical ventilation.

METHODS

Overall, 65 eligible intubated patients with no initial signs of pulmonary infection were studied over a period of up to 7 days. Tracheobronchial aspirates were taken: (i) within 48 h after intubation; and (ii) when clinical signs of nosocomial tracheobronchitis were present, before extubation, or after 7 days. Presence of respiratory viruses was investigated using quantitative polymerase chain reaction.

RESULTS

Patients were 67 +/- 11 years old and had been in hospital for 5.1 +/- 8.4 days when intubated (major cause for intubation: cardio-pulmonary resuscitation 25/65, 38%). The average Acute Physiology and Chronic Evaluation II score was 27.3 +/- 4.9. Microbiology detected Candida spp. (17/65; 26%) and Staphylococcus aureus (methicillin sensitive: 11/65; 17%; methicillin resistant: 3/65; 5%) and only few respiratory viruses (4/65, 6%). Thirty-eight percent of the samples (25/65) were sterile. At the given endpoints, 27/65 (42%) patients were available for follow-up and only one aspirate became positive for respiratory syncytial virus (RSV).

CONCLUSIONS

After endotracheal intubation, fungi, but not viruses were most frequently isolated. Only one patient acquired RSV, therefore colonization with respiratory viruses does not seem to play a major role early after intubation.

[Recurrent Candida sepsis with prolonged respiratory failure and severe liver dysfunction]

Systemic mycoses, especially pulmonary diseases and septicemia are observed increasingly at intensive care units. Essential risk factors for development of candidosis are the expanded use of antibiotics and immunocompromised patients, caused either as a result of a severe underlying disease or iatrogenically induced after organ transplantation. Candida albicans is the most frequent pathogen in microbiological findings. Blood cultures are only positive in massive fungemia. We report a 50-year-old patient with recurrent Candida-septicemia: rupture of the distal esophagus after dilatation because of cardiac achalasia with mediastinal emphysema and mediastinitis. Severe acute respiratory distress syndrome after aspiration with septic shock and acute renal failure at the beginning. Long-term mechanical ventilation, continuous renal replacement therapy and multifarious antibiotic therapy. Early microbiological samples of several positive blood cultures and bronchoalveolar lavages revealed the presence of Candida albicans. In the further clinical course, detection of Pseudomonas species in bronchoalveolar lavages and Staphylococci as well as Enterococci in a number of positive blood cultures. Later on development of a severe liver dysfunction with test results that showed an intrahepatic cholestasis. Because of coagulation failure commencement of artificial liver support with the MARS-system (molecule adsorbent recirculating system). Decrease of high bilirubin levels was accompanied by improvement of clinical condition of the patient. In the following course, repeated severe systemic infections with phases of septicemia or rather septic shock and detection of Candida in several positive blood cultures and bronchoalveolar lavages. In each case increasing bilirubin levels with signs of intrahepatic cholestasis and each time improvement with antimycotic therapy (voriconazol, caspofungin and fluconazol). The patient showed more and more signs of immunodeficiency in the sequel. The clinical appearance of candidosis is manifold. Systemic Candida infections are frequent in patients with immunodeficiency. A recurrent Candida septicemia with prolonged respiratory failure and severe liver dysfunction in form of cholestatic hepatosis, that improved several times with antimycotic therapy in combination with evidence based intensive care measures and artificial organ support is a comparatively rare event.

In vitro susceptibility of yeasts isolated from patients in intensive care units to fluconazole and amphotericin B during a 3-year period

Fungal infections have increased dramatically in recent years and candidemia is a major risk factor for morbidity and mortality in intensive care units (ICUs). Candidemia has been considered to be a nosocomial infection that is strongly associated with neutropenia, recent surgery or presence of intravascular lines, and previous colonization is an independent risk factor. We evaluated the in vitro efficacy of fluconazole and amphotericin B against yeasts isolated from various clinical specimens of colonized or infected patients treated in the ICUs of the Institute of Cardiology, Istanbul University. A total of 1397 ICU patients were treated at the Institute of Cardiology between January 2000 and December 2002. A total of 117 yeasts isolated from 97 patients were included in this study. These ICU patients were hospitalized for a mean of 29 days. All yeasts were identified by conventional methods and using the API (20C AUX, ID 32C) system (Bio Meriéux, France). Susceptibility to fluconazole and amphotericin B was evaluated using the E-test (AB Biodisk, Solna, Sweden). The most commonly isolated yeast was Candida albicans (72.6%), followed by Candida tropicalis (16.2%), Candida kefyr, Candida krusei, Candida parapsilosis, Trichosporon mucoides and Geotrichum spp. Fluconazole and amphotericin B MIC90 values were 0.75 microg/ml; 0.19 microg/ml and 1 microg/ml; 0.38 microg/ml for C. albicans and C. tropicalis, respectively. All Geotrichum spp. were found to be susceptible-dose dependent (SDD) (MIC=16-32 microg/ml) to fluconazole. Two C. albicans, two C. tropicalis, one C. krusei and one Geotrichum spp. had a MIC value of > or = 0.38 microg/ml for amphotericin B. The rate of colonization was 3.36% (47/1397). Only 10 (0.71%) patients out of a total of 1397 developed candidemia during the period of the investigation. Of these, 7 (70%) were caused by non-albicans Candida spp.

Nanoscale investigation of pathogenic microbial adhesion to a biomaterial

Microbial infections of medical implants occur in more than 2 million surgical cases each year in the United States alone. These increase patient morbidity and mortality, as well as patient cost and recovery time. Many treatments are available, but none are guaranteed to remove the infection. In many cases, the device infections are caused by the adhesion of microbes to the implant, ensuing growth, pathogenesis, and dissemination. The purpose of this work is to examine the initial events in microbial adhesion by simulating the approach and contact between a planktonic cell, immobilized on an atomic force microscope (AFM) cantilever, and a biomaterial or biofilm substrate. The two model microbes used in this study, Candida parapsilosis (ATCC 90018) and Pseudomonas aeruginosa (ATCC 10145), were chosen for both their clinical relevance and their ease of acquisition and handling in the laboratory setting. Attractive interactions exist between C. parapsilosis and both unmodified silicone rubber and P. aeruginosa biofilms. Using C. parapsilosis cells immobilized on AFM cantilevers with a silicone substrate, we have measured attractive forces of 4.3 +/- 0.25 nN in the approach portion of the force cycle. On P. aeruginosa biofilms, the magnitude of the attractive force decreases to 2.0 +/- 0.40 nN and is preceded by a 2.0-nN repulsion at approximately 75 nm from the cell surface. These data suggest that C. parapsilosis may adhere to both silicone rubber and P. aeruginosa biofilms, possibly contributing to patient morbidity and mortality. Characterization of cell-biomaterial and cell-cell interactions allows for a quantitative link between the physicomechanical and physicochemical properties of implant materials and the nanoscale interactions leading to microbial colonization and infection.

Recent advances in the epidemiology, prevention, diagnosis, and treatment of fungal pneumonia

Although pneumonia caused by fungi is not a common occurrence in the general population, disease in an enlarging immunocompromised population is encountered with increasing frequency. Fungal pneumonias are most frequently caused by Aspergillus spp., dimorphic fungi and Cryptococcus neoformans. Recent studies have identified risk factors of thrombocytopenia, environmental events (such as construction or renovation) and immunosuppressive drug therapies as being specific risk factors for invasive fungal disease in select patient populations. Diagnostic strategies to detect circulating antigens and polymerase chain reaction based detection systems have been explored to improve identification prior to the progressive advanced disease. Advances in prophylactic strategies include increased use of aerosolized formulations of amphotericin B, usually in conjunction with new and old systemic antifungal agents. Despite recent published guidelines for treatment of fungal pneumonia based on etiology, mortality remains high in some infections with advanced disease. Caspofungin, a new echinocandin antifungal, has recently been approved by the US Food and Drug Administration for the treatment of invasive Aspergillus infections in patients unresponsive to or unable to receive amphotericin B. A triazole antifungal, voriconazole, has shown promise in phase III clinical trials in patients with refractory fungal infections and is expected to be available in early 2002. Other echinocandin and triazole antifungals are under development in attempts to provide improved effective therapy for fungal pneumonia.