We evaluated whether the likelihood of developing invasive candidiasis (IC) differed depending upon the anatomic site of
Candida colonization in 182 surgical intensive care unit (SICU) patients who ...participated in a randomized trial of fluconazole to prevent candidiasis. We also determined the impact of
Candida colonization of different anatomic sites on all-cause SICU and hospital mortality. A total of 2851 surveillance fungal cultures collected from 5 anatomic sites were analyzed. There was a statistically significant difference in the frequency of IC comparing patients with and without urinary (13.2% versus 2.8%,
P = .02), respiratory (8.0% versus 1.2%,
P = .04), and rectum/ostomy (8.4% versus 0%,
P = .01) colonization. Patients with negative rectum/ostomy cultures and patients with both negative urine and respiratory tract cultures did not develop IC. Candiduria detected at any time in the SICU was independently associated with SICU mortality (odds ratio, 2.86; 95% confidence interval, 1.05–7.74). Surveillance fungal cultures of particular anatomic sites may help differentiate patients at higher risk of developing IC from those at low risk.
Filamentous fungal infections have recently increased because of the increasing numbers of immunocompromised hosts. In this study, we evaluated DNA sequencing of the D1/D2 region of the large subunit ...of the 28S ribosomal RNA gene and the internal transcribed spacer (ITS) region using SmartGene (SG; SmartGene Inc., Raleigh, NC) for the identification of a broad range of commonly encountered filamentous fungi. The SG proofreaders were used to upload, align, and edit fragments, and the resultant sequences were interpreted using the quality-controlled SG database. The results were compared with reference identifications using conventional phenotypic methods or ITS DNA sequences obtained from GenBank if phenotypic identifications were inconclusive. A total of 146 clinical isolates were included in this study, representing 49 different genera. The overall agreements of the D1/D2 and the ITS sequencing methods to reference identification were 97.2% (95% CI, 93.1% to 98.9%) and 97.7% (95% CI, 92.8% to 99.4%), respectively. Of the 146 isolates, 18 (12.3%) did not amplify using the ITS universal primers after repeated attempts and, therefore, could not be sequenced using this target. Correct identification was achieved for 100% (95% CI, 97.4% to 100%) of the isolates when applying both the D1/D2 and ITS targets. In summary, DNA sequencing using SG software provides a rapid, accurate, and reliable tool for the identification of filamentous fungi in a clinical laboratory.
A cross-sectional study was conducted to assess the prevalence and microbiology of oral infection due to fluconazole-resistant Candida in patients with AIDS. Oral swab specimens for fungal cultures ...were obtained from 100 consecutive outpatients with CD4 lymphocyte counts of <200/mm3. At least one fungal organism demonstrating in vitro resistance to fluconazole (minimum inhibitory concentration, ⩾8μg/mL) was isolated from 26 (41%) of 64 patients for whom cultures were positive. When fluconazole-resistant C. albicans was isolated, in vitro resistance correlated with clinical thrush. None of 10 patients from whom only non-albicans species of Candida were isolated had active thrush. The patients from whom fluconazole-resistant Candida albicans was isolated had lower CD4 cell counts (median, 9/mm3), a greater number of treated episodes of thrush (median, 4.5), and a greater median duration of prior fluconazole treatment (231 days) than did patients from whom fluconazole-susceptible C. albicans was isolated (median CD4 cell count, 58/mm3 P = .004; median number of treated episodes of thrush, 2.0 P = .001; and median duration of prior fluconazole treatment, 10 days P = .01; respectively). In a multivariate analysis, the number of episodes and duration of fluconazole therapy were independent predictors of resistance.
Infection Control surveillance revealed an abnormally high number of sputum samples growing Mycobacterium fortuitum from a single ward that houses the human immunodeficiency virus service. We ...investigated the outbreak using a retrospective case-control study and molecular epidemiology. A total of 47 patients were identified with ⩾1 sputum sample that grew M. fortuitum. No significant demographic or clinical variables were found to be associated with colonization. Environmental investigation demonstrated that the M. fortuitum isolated from patients was identical to the ice machine isolates by pulsed-field gel electrophoresis. Fortunately, there has been no evidence of progressive pulmonary disease developing in our patients after ⩾6 months of follow-up. All cases were thought to represent transient colonization and not infection. The ice machine was disconnected and cleaned successfully with vinegar and then bleach. Only when a 0.5-µm filter was installed were no further patients colonized or water cultures found to be positive.
To investigate an outbreak of aspergillosis in a leukemia and bone marrow transplant (BMT) unit and to improve environmental assessment strategies to detect Aspergillus.
Epidemiological investigation ...and detailed environmental assessment.
A tertiary-care university hospital with a 37-bed leukemia and BMT unit
Leukemic or BMT patients with invasive aspergillosis identified through prospective surveillance and confirmed by chart review.
We verified the diagnosis of invasive fungal infection by reviewing medical charts of at-risk patients, performing a case-control study to determine risk factors for infection, instituting wet mopping to clean all floors, providing N95 masks to protect patients outside high-efficiency particulate air (HEPA)-filtered areas, altering traffic patterns into the unit, and performing molecular typing of selected Aspergillus flavus isolates. To assess the environment, we verified pressure relationships between the rooms and hallway and between buildings, and we compared the ability of large-volume (1,200 L) and small-volume (160 L) air samplers to detect Aspergillus spores.
Of 29 potential invasive aspergillosis cases, 21 were confirmed by medical chart review. Risk factors for developing invasive aspergillosis included the length of time since malignancy was diagnosed (odds ratio OR, 1.0; P=.05) and hospitalization in a patient room located near a stairwell door (OR, 3.7; P=.05). Two of five A. flavus patient isolates were identical to one of the environmental isolates. The pressure in most of the rooms was higher than in the corridors, but the pressure in the oncology unit was negative with respect to the physically adjacent hospital; consequently, the unit acted essentially as a vacuum that siphoned non-HEPA-filtered air from the main hospital. Of the 78 samples obtained with a small-volume air sampler, none grew an Aspergillus species, whereas 10 of 40 cultures obtained with a large-volume air sampler did.
During active construction, Aspergillus spores may have entered the oncology unit from the physically adjacent hospital because the air pressure differed. Guidelines that establish the minimum acceptable pressures and specify which pressure relationships to test in healthcare settings are needed. Our data show that large-volume air samples are superior to small-volume samples to assess for Aspergillus in the healthcare environment.
The goal of this study was to determine the factor(s) explaining our inability to detect Candida dubliniensis. When germ tube-positive yeasts were tested for C. dubliniensis, no C. dubliniensis was ...detected; however, 58 C. dubliniensis strains were detected when germ tube-negative Candida albicans strains were tested further. Since all 58 C. dubliniensis strains detected were germ tube negative, these data implied that false-negative germ tube tests occurred with germ tube solution (GTS; Remel, Lenexa, KS). All 41 known C. dubliniensis strains tested were negative with GTS, whereas 40 were positive with rabbit serum (RS; Sigma-Aldrich, St. Louis, MO). Results for C. albicans were equivalent in GTS and RS. In conclusion, GTS cannot be used for the detection of C. dubliniensis, and switching from yeast to hyphae in C. dubliniensis is more restricted than in C. albicans.
Trichosporon species are an emerging cause of infection, particularly among transplant recipients. We report what we believe to be the first case of successful management of disseminated Trichosporon ...mucoides infection with orally administered fluconazole in a heart and kidney transplant recipient.
Little is known about the relationships between metabolic activity and fungal biomass or time of incubation for medically important fungal pathogens. Understanding these relationships may be ...especially relevant for rapidly growing organisms, such as zygomycetes. A range of inocula of five clinical isolates of zygomycetes (one each of Rhizopus oryzae,Rhizopus microsporus, Cunninghamella bertholletiae, Mucor circinelloides and Absidia corymbifera) were incubated for 6, 8, 12, 24 and 48 h, after which hyphal mass was assessed spectrophotometrically and metabolic activity was measured using various concentrations of XTT and menadione. Both linear regression and the Boltzmann sigmoid model were used and compared for description of relationships between metabolic activity, biomass and time of incubation. Modeling was further applied to eleven additional zygomycete isolates. The relationships of biomass or metabolic activity as a function of time of incubation were well described with the Boltzmann sigmoid model. The latter was superior to linear regression in describing the relationship between metabolic activity and fungal biomass. For all isolates of zygomycetes, increases in metabolic activity preceded increases in biomass. Inter-species differences in growth patterns were observed, with Rhizopus microsporus and Mucor spp. reaching the plateau of growth earlier compared to other species. These findings on the temporal relationship and inter-species differences of hyphal growth and metabolic activity for zygomycetes may be useful in the design and interpretation of in vitro studies of these emerging pathogens.
Exposure to Aspergillus fumigatus is linked with respiratory diseases such as asthma, invasive aspergillosis, hypersensitivity pneumonitis, and allergic bronchopulmonary aspergillosis. Molecular ...methods using quantitative PCR (qPCR) offer advantages over culture and optical methods for estimating human exposures to microbiological agents such as fungi. We describe an assay that uses lyticase to digest A. fumigatus conidia followed by TaqMan qPCR to quantify released DNA. This method will allow analysis of airborne A. fumigatus samples collected over extended time periods and provide a more representative assessment of chronic exposure. The method was optimized for environmental samples and incorporates: single tube sample preparation to reduce sample loss, maintain simplicity, and avoid contamination; hot start amplification to reduce non-specific primer/probe annealing; and uracil-N-glycosylase to prevent carryover contamination. An A. fumigatus internal standard was developed and used to detect PCR inhibitors potentially found in air samples. The assay detected fewer than 10 A. fumigatus conidia per qPCR reaction and quantified conidia over a 4-log10 range with high linearity (R2 >0.99) and low variability among replicate standards (CV=2.0%) in less than 4 h. The sensitivity and linearity of qPCR for conidia deposited on filters was equivalent to conidia calibration standards. A. fumigatus DNA from 8 isolates was consistently quantified using this method, while non-specific DNA from 14 common environmental fungi, including 6 other Aspergillus species, was not detected. This method provides a means of analyzing long term air samples collected on filters which may enable investigators to correlate airborne environmental A. fumigatus conidia concentrations with adverse health effects.
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