15168745
First Report of Ventriculoperitoneal Shunt Infection due to Cyberlindnera fabianii
Fungal infections in the central nervous system (CNS) are associated with significant morbidity and death. Transient fungemia in immunocompetent patients without any other risk factors for fungemia has been suggested as a possible mechanism that may lead to serious fungal ventriculoperitoneal (VP) shunt infections, but evidence is lacking. The clinical spectrum, diagnosis, and optimal therapy of Cyberlindnera fabianii infections remain to be determined. We describe the first case of CNS infection due to C. fabianii that occurred in an immunocompetent adult with a VP shunt. Spontaneous translocation with yeast that is not part of the normal gastrointestinal flora in the setting of ingestion of multiple servings of a fermentation product was the likely source from which Cyberlindnera fabianii gained entrance into the VP shunt system, causing meningitis in this patient. The authors conclude that, in view of the high morbidity associated with yeast infection of the CNS, long-term antifungal therapy should be strongly considered in cases where the VP shunt cannot be completely removed. Transient fungemia may lead to invasive disease in an immunocompetent host with VP shunt, even in the absence of any other risk factors for fungemia and even after remote placement of the VP shunt.
17262404
Candida Infections of Medical Devices
SUMMARY The number of indwelling medical devices is escalating, and an increasing proportion of device-related infections are being caused by Candida spp. Candida spp. produce biofilms on synthetic materials, which facilitates adhesion of the organisms to devices and renders them relatively refractory to medical therapy. Management of device-related Candida infections can be challenging. Removal of the infected device is generally needed to establish cure of Candida infections of medical devices. However, since the pathogenesis of Candida bloodstream infection is complicated, more studies are necessary to determine the role of catheter exchange in patients with both gastrointestinal tract mucositis and indwelling catheters. The medical and economic impact of these infections is enormous.
21794329
Candidal infections of ventriculoperitoneal shunts
Although ventriculoperitoneal (VP) shunt infection is a common complication of shunt procedures, fungal infection is considered to be rare. In the present study, we performed retrospective analysis of six cases in which candida infection occurred. In all these six cases, VP shunt was performed in children for hydrocephalus and the onset of symptoms varied between seven days to one month after the surgical procedure was performed. The commonest clinical signs and symptoms were fever (100%), vomiting (100%), and altered sensorium (50%). The commonest isolate was Candida albicans (66.66%) followed by Candida parapsilosis and Candida glabrata in one case each. All the patients were successfully treated with Amphotericin B and there was no mortality recorded.
23587131
Meningitis caused by Candida species: an emerging problem in neurosurgical patients.
Three cases of candida meningitis were encountered in a 3-year period in our hospital; all occurred in neurosurgical patients. We describe these three cases and review the 15 cases of neurosurgery-related candida meningitis previously reported in the English-language literature. Data regarding these 18 patients formed the basis for our review. Most patients with candida meningitis had recently received antibacterial agents, and it is notable that 50% of patients suffered from antecedent bacterial meningitis. The CSF analysis revealed neutrophilic pleocytosis that was indistinguishable from that of bacterial meningitis. The overall mortality was 11%. Administration of amphotericin B combined with flucytosine appeared to be the best therapeutic approach for candida meningitis.
37745991
Candida albicans shunt infection.
Seven cases of successfully treated Candida albicans cerebrospinal fluid shunt infections are reported. Treatment consisted of shunt removal and intravenous Amphotericin B in all cases and intraventricular Amphotericin B in 4 cases. Serious underlying medical illness, recent antibiotic therapy, indwelling intravascular and/or Foley catheters, coincident candidiasis and low birth weight prematurity are major risk factors for candida shunt infection. Candida shunt infection appears to occur by either contamination at the time of shunt placement or by hematogenous dissemination.
20486529
Genome Sequence of the Yeast Cyberlindnera fabianii (Hansenula fabianii)
ABSTRACT The yeast Cyberlindnera fabianii is used in wastewater treatment, fermentation of alcoholic beverages, and has caused blood infections. To assist in the accurate identification of this species, and to determine the genetic basis for properties involved in fermentation and water treatment, we sequenced and annotated the genome of C. fabianii (YJS4271).
21087427
Phylogenetic relationships among species of Pichia, Issatchenkia and Williopsis determined from multigene sequence analysis, and the proposal of Barnettozyma gen. nov., Lindnera gen. nov. and Wickerhamomyces gen. nov.
Relationships among species assigned to the yeast genera Pichia, Issatchenkia and Williopsis, which are characterized by the ubiquinone CoQ-7 and inability to utilize methanol, were phylogenetically analyzed from nucleotide sequence divergence in the genes coding for large and small subunit rRNAs and for translation elongation factor-1alpha. From this analysis, the species separated into five clades. Species of Issatchenkia are members of the Pichia membranifaciens clade and are proposed for transfer to Pichia. Pichia dryadoides and Pichia quercuum are basal members of the genus Starmera. Williopsis species are dispersed among hat-spored taxa in each of the remaining three clades, which are proposed as the new genera Barnettozyma, Lindnera and Wickerhamomyces. Lineages previously classified as varieties of Pichia kluyveri, 'Issatchenkia'scutulata, Starmera amethionina and 'Williopsis'saturnus are elevated to species rank based on sequence comparisons.
22698749
Identification of Candida fabianii as a cause of lethal septicaemia
Infections caused by rare fungal species of low pathogenic potential become increasingly common in hospital settings. The identification of these species presents a major challenge for the clinical mycology laboratory. We describe a case of fatal septicaemia caused by Candida fabianii. The use of common biochemical approaches led to misidentification of the isolate as Candida utilis. Sequencing of the internal transcribed spacer regions (ITS1 and ITS2) allowed unequivocal species identification.
25476890
Infection in a neonate caused by Pichia fabianii: importance of molecular identification.
Pichiafabianii, an uncommon yeast species recovered from clinical specimens, was documented as the cause of an infection in a 5-week-old female twin delivered at 25 and 3/7 weeks. She developed respiratory distress syndrome and necrotizing enterocolitis. At the time of the infection, she was febrile, thrombocytopenic, and still was requiring minimal ventilatory support. Blood cultures drawn on two consecutive days were positive for a germ tube negative yeast. Phenotypic methods including carbohydrate fermentations and assimilations (API 20C AUX) did not identify the yeast. Sequencing of D1/D2 domain of the large subunit rDNA was performed in one laboratory and sequencing a subunit of D2 performed in a second laboratory identified the yeast as P. fabianii. The organism was susceptible in vitro to amphotericin B, fluconazole and 5-fluorocytosinc. The patient responded to amphotericin B and removal of her vascular catheter. This case illustrates that there are an increasing number of fungi that may be pathogenic. Phenotypic tests may fail to identify them, emphasizing the need for commercially available, molecular based assays for identification.
8058702
Pichia fabianii blood infection in a premature infant in China: case report
BackgroundInvasive fungal infections caused by uncommon fungi have increased in recent years. Hospitalized low-birth-weight infants are at high risk for neonatal fungal infections. Pichia fabianii is a rare pathogen causing blood infection, which has reportedly caused only 4 cases of fungemia and 1 case of endocarditis worldwide. Here, we describe the first case of a P. fabianii blood infection in a premature infant in China.Case presentationOn July 28th, a low-birth-weight (LBW, 1760 g) female infant born at 33+4 weeks of gestation was admitted to the pediatric intensive care unit with mild neonatal asphyxia. Until August 2nd, a mechanical respirator was used to assist respiration under the Continuous Positive Airway Pressure (CPAP) model. The baby had an increased body temperature and a fever. To prevent infection, Ceftriaxone Sodium (CS) was administered intravenously for three days, after which Cefepime was administered until August 13th. Chest X-rays showed suspected plaque-like shadows in the right lung. Blood cultures twice tested positive for fungal infection caused by Candida pelliculosa (recognized as Pichia fabianii later), which is first mis-identified by commercial kit. Hence, intravenous fluconazole was administered. However, cultures of other body fluids (e.g., urine, feces and sputum) tested negative for fungal infection. Routine tests and biochemistry of cerebrospinal fluid (CSF) were normal. Latex agglutination of Cryptococcus neoformans and fungi cultures in the CSF were also negative. After 14 days of intravenous fluconazole, blood was re-cultured, the result of which was negative. On August 30th, intravenous fluconazole was suspended. On Sep 3rd, the infant left the hospital in good health.ConclusionsThis is the first case of a blood infection caused by P. fabianii in a LBW premature female infant in China. Risk factors for fungal infection include premature birth, as well as mechanical invasive operation and antibacterial drug usage. Whether such risk factors necessitate prophylactic use of antifungal drugs is an important question that has yet to be fully addressed. Additionally, the pathogen P. fabianii collected in this study was resistant to amphotericin B (AMB) and itraconazole (ITR). With the exception of the azole-resistant endocarditis case, all other cases have not demonstrated such a resistance. Finally, commercial biochemical methods used in routine practice are limited in their ability to identify P. fabianii. Molecular genetic based methods are imperative for identification of uncommon fungal species from disseminated infections.
39667846
Lindnera (Pichia) fabianii blood infection after mesenteric ischemia.
Lindnera (Pichia) fabianii (teleomorph of Candida fabianii) is a yeast species rarely involved in human infections. This report describes the first known human case of a Lindnera fabianii blood infection after mesenteric ischemia. The 53-year-old patient was hospitalized in the intensive care unit after a suicide attempt and was suffering from a mesenteric ischemia and acute renal failure. Lindnera fabianii was recovered from an oropharyngeal swab, then isolated from stool and urine samples before the diagnosis of the blood infection. Caspofungin intravenous treatment was associated with a successful outcome. Final unequivocal identification of the strain was done by sequencing the internal transcribed spacer (ITS) region, and regions of 18S rDNA gene and of the translation elongation factor-1α gene. Until our work, the genomic databases did not contain the complete ITS region of L. fabianii as a single nucleotide sequence (encompassing ITS1, the 5.8S rDNA and ITS2), and misidentification with other yeast species, e.g., Lindnera (Pichia) mississippiensis, could have occurred. Our work demonstrates that the usual DNA barcoding method based on sequencing of the ITS region may fail to provide the correct identification of some taxa, and that partial sequencing of the EF1α gene may be much more effective for the accurate delineation and molecular identification of new emerging opportunistic yeast pathogens.
25742957
Catheter-related bloodstream infection by Lindnera fabianii in a neutropenic patient.
Lindnera (Pichia) fabianii (Candida fabianii teleomorph) is a yeast species that is an uncommon cause of invasive human infections. This report describes what we believe to be the first human case of a catheter-related L. fabianii bloodstream infection in a neutropenic patient. The Clinical and Laboratory Standards Institute guidelines do not offer antifungal breakpoints in this neutropenic case and empirical chemotherapy was considered. Sharing our experience, we will discuss the choice of an effective antifungal agent in this uncommon clinical situation.
53491273
Cyberlindnera fabianii in the neonatal and paediatric intensive care unit: case reports
Introduction:
The number of infections due to uncommon yeast species is gradually increasing worldwide. In cases of high-risk paediatric patients, Cyberlindnera fabianii has been identified as the causal agent in a number of countries. In fact, we have recently reported the first proven occurrence, to the best of our knowledge, of this species as a causal agent of fungaemia in three neonatal patients in a Croatian hospital.
Case presentation:
We report here six new instances of clinically manifested bloodstream and urinary tract infections caused by Cyberlindnera fabianii in five high-risk neonates and one child, during a 5-year period (2008–2012) in the aforementioned Croatian hospital. In addition, we have provided an account of their treatment strategy and the outcome, and the susceptibility profiles of 44 isolates of Cyberlindnera fabianii to amphotericin B, flucytosine, triazoles and echinocandins. Furthermore, we have described a novel molecular method suitable for the rapid and specific diagnosis of this species.
Conclusion:
Our findings demonstrated: (i) the pathogenic activities of Cyberlindnera fabianii species in high-risk children; (ii) that administering fluconazole either prophylactically or therapeutically yielded no results in 50 % of the patients; (iii) that substituting fluconazole by liposomal amphotericin B or caspofungin managed to resolve sepsis in the remaining 50 % of patients; (iv) that, according to the examined sequences, all of the Cyberlindnera fabianii isolates were found to be identical independent of their source or study period; and (v) the existence of a higher proportion of non-susceptible isolates of Cyberlindnera fabianii for echinocandins (especially micafungin) compared with the other tested antifungals.
13770385
Monitoring and impact of fluconazole serum and cerebrospinal fluid concentration in HIV‐associated cryptococcal meningitis‐infected patients
Objectives The aim of the present study was to assess fluconazole pharmacokinetic measures in serum and cerebrospinal fluid (CSF); and the correlation of these measures with clinical outcomes of invasive fungal infections.
1754119
Comparison of Inhibitory Mold Agar to Sabouraud Dextrose Agar as a Primary Medium for Isolation of Fungi
ABSTRACT Clinical specimens cultured on two selective fungal media, inhibitory mold agar (IMA) and Sabouraud dextrose agar (SDA), were compared with respect to recovery of fungi. Of the 840 fungal isolates recovered, 69.3% grew on both IMA and SDA; 24.9% grew only on IMA; and 5.8% grew only on SDA, showing that IMA is superior (P = 0.003).
32570917
Identification of Medically Important Yeast Species by Sequence Analysis of the Internal Transcribed Spacer Regions
ABSTRACT Infections caused by yeasts have increased in previous decades due primarily to the increasing population of immunocompromised patients. In addition, infections caused by less common species such as Pichia, Rhodotorula, Trichosporon, and Saccharomyces spp. have been widely reported. This study extensively evaluated the feasibility of sequence analysis of the rRNA gene internal transcribed spacer (ITS) regions for the identification of yeasts of clinical relevance. Both the ITS1 and ITS2 regions of 373 strains (86 species), including 299 reference strains and 74 clinical isolates, were amplified by PCR and sequenced. The sequences were compared to reference data available at the GenBank database by using BLAST (basic local alignment search tool) to determine if species identification was possible by ITS sequencing. Since the GenBank database currently lacks ITS sequence entries for some yeasts, the ITS sequences of type (or reference) strains of 15 species were submitted to GenBank to facilitate identification of these species. Strains producing discrepant identifications between the conventional methods and ITS sequence analysis were further analyzed by sequencing of the D1-D2 domain of the large-subunit rRNA gene for species clarification. The rates of correct identification by ITS1 and ITS2 sequence analysis were 96.8% (361/373) and 99.7% (372/373), respectively. Of the 373 strains tested, only 1 strain (Rhodotorula glutinis BCRC 20576) could not be identified by ITS2 sequence analysis. In conclusion, identification of medically important yeasts by ITS sequencing, especially using the ITS2 region, is reliable and can be used as an accurate alternative to conventional identification methods.
39483407
New Heterothallic species of Hansenula
As the genusHansenula is at present constituted,H. fabianii appears to be the first species of its phylogenetic line to have become independent of trees and bark beetles. It is also the last species of its line to occur in nature with the haploid, or basic, number of chromosomes. So near is it to the diploid level of evolution that a sporulation medium rich in malt extract favors the development of diploid vegetative cells in the period between conjugation of opposite sexes and the onset of sporulation. The diploid form is easily isolated from the mixture and, as long as sporulation is prevented, may be kept in pure state. Media that favor vegetative development of the species favor its occurrence as haploid vegetative cell.H. fabianii is most closely related toHansenula subpelliculosa Bedford, which occurs in nature as the diploid form. Both species have been isolated almost exclusively as contaminants of fermentations, and both have been used industrially in Oriental fermentations to make alcoholic beverages or foods.
43009024
Evaluation of sporulation media for yeasts obtained from pathological material.
Summary
Non-pathogenic perfect yeasts isolated from clinical material are sometimes erroneously identified as species of imperfect genera, such as Candida, because sporulation studies have not been made. Such misidentified isolates may be regarded as pathogens.
The sporulation characteristics of two haploid mating strains of Hansenula anomala and three homothallic strains of Saccharomyces cerevisiae of indifferent sporing quality were examined, by comparing clonally related isolates derived from single vegetative cells, or from ascospores. The haploid strains produced spores only after mating. The media tested were sodium acetate agar, Gorodkowa agar, and V8 agar, and two temperatures of incubation, 23°C and 30°C, were used.
All subcultures of S. cerevisiae spored within 25 days on sodium acetate agar, and sporing occurred more rapidly at 23°C; 67 per cent. spored at 5 days. Subcultures of H. anomala spored within 3 days. This medium is therefore recommended for use in diagnostic laboratories in the investigation of yeast isolates that cannot be identified readily as to genus or species.
206787886
Evaluation of a Short, On-Plate Formic Acid Extraction Method for Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry-Based Identification of Clinically Relevant Yeast Isolates
ABSTRACT This report describes a short, on-plate formic acid (FA) extraction method for the identification of clinical yeast isolates using matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI-TOF MS). A total of 41.1% (78/190) and 63.7% (121/190) of yeasts were identified using species log score thresholds of >2.0 and >1.9, respectively. Overall, 97.4% (185/190) of yeasts were identified in combination with conventional FA extraction.
16191628
Pichia anomala (Candida pelliculosa) Fungemia in a Patient with Sickle Cell Disease
This case report discusses a patient with sickle cell disease who presented with fungemia from Pichia anomala (teleomorph: Candida pelliculosa). The organism was identified as P. anomala by MALDI-TOF VITEK mass spectrometry and VITEK 2 yeast identification card. Pichia anomala should be considered in sickle cell patients with recurrent fungemia.
31209641
Fermentation characteristics of yeasts isolated from traditionally fermented masau (Ziziphus mauritiana) fruits.
Yeast strains were characterized to select potential starter cultures for the production of masau fermented beverages. The yeast species originally isolated from Ziziphus mauritiana (masau) fruits and their traditionally fermented fruit pulp in Zimbabwe were examined for their ability to ferment glucose and fructose using standard broth under aerated and non-aerated conditions. Most Saccharomyces cerevisiae strains were superior to other species in ethanol production. The best ethanol producing S. cerevisiae strains, and strains of the species Pichia kudriavzevii, Pichia fabianii and Saccharomycopsis fibuligera were tested for production of flavor compounds during fermentation of masau fruit juice. Significant differences in the production of ethanol and other volatile compounds during fermentation of masau juice were observed among and within the four tested species. Alcohols and esters were the major volatiles detected in the fermented juice. Trace amounts of organic acids and carbonyl compounds were detected. Ethyl hexanoate and ethyl octanoate were produced in highest amounts as compared to the other volatile compounds. S. cerevisiae strains produced higher amounts of ethanol and flavor compounds as compared to the other species, especially fatty acid ethyl esters that provide the major aroma impact of freshly fermented wines. The developed library of characteristics can help in the design of mixtures of strains to obtain a specific melange of product functionalities.
35234359
Molecular identification of yeast species associated with 'Hamei'--a traditional starter used for rice wine production in Manipur, India.
In Manipur state of North-Eastern India, wine from glutinous rice using traditional solid state starter called 'Hamei' is particularly interesting because of its unique flavour. A total of 163 yeast isolates were obtained from fifty four 'Hamei' samples collected from household rice wine preparations in tribal villages of Manipur. Molecular identification of yeast species was carried out by analysis of the restriction digestion pattern generated from PCR amplified internal transcribed spacer region along with 5.8S rRNA gene (ITS1-5.8S-ITS2). Seventeen different restriction profiles were obtained from the size of PCR products and the restriction analysis with three endonucleases (Hae III, Cfo I and Hinf I). Nine groups were identified as S. cerevisiae, Pichia anomala, Trichosporon sp., Candida tropicalis, Pichia guilliermondi, Candida parapsilosis, Torulaspora delbrueckii, Pichia fabianii and Candida montana by comparing this ITS-RFLP profile with type strains of common wine yeasts, published data and insilico analysis of ITS sequence data available in CBS yeast database. ITS-RFLP profile of eight groups was not matching with available database of 288 common wine yeast species. The most frequent yeast species associated with 'Hamei' were S. cerevisiae (32.5%), P. anomala (41.7%) and Trichosporon sp. (8%). The identity of major groups was confirmed by additional restriction digestion of ITS region with Hind III, EcoRI, Dde I and Msp I. The genetic diversity of industrially important S. cerevisiae group was investigated using Pulsed Field Gel Electrophoresis (PFGE). Although most of the 53 strains of S. cerevisiae examined were exhibited a common species specific pattern, a distinct degree of chromosomal length polymorphism and variable number of chromosomal DNA fragments were observed with in the species. Cluster analysis showed seven major karyotypes (K1-K7) with more than 83% similarity. The karyotype pattern K1 was the most frequent (67.9%) among the strains from different samples. Other karyotypes K2-K7 were very unique with less than 80% similarity. Finally using mitochondrial DNA restriction analysis (mt-DNA RFLP), S. cerevisiae strains belonging to the major karyotype K1 were distinctly differentiated with highly polymorphic bands by Hinf I and Hae III endonucleases.
3797351
Saccharomyces cerevisiae fungemia: an emerging infectious disease.
BACKGROUND
Saccharomyces cerevisiae is well known in the baking and brewing industry and is also used as a probiotic in humans. However, it is a very uncommon cause of infection in humans.


METHODS
During the period of 15-30 April 2003, we found 3 patients with S. cerevisiae fungemia in an intensive care unit (ICU). An epidemiological study was performed, and the medical records for all patients who were in the unit during the second half of April were assessed.


RESULTS
The only identified risk factor for S. cerevisiae infection was treatment with a probiotic containing Saccharomyces boulardii (Ultralevura; Bristol-Myers Squibb). This probiotic is used in Europe for the treatment and prevention of Clostridium difficile-associated diarrhea. The 3 patients received the product via nasograstric tube for a mean duration of 8.5 days before the culture result was positive, whereas only 2 of 41 control subjects had received it. Surveillance cultures for the control patients admitted at the same time did not reveal any carriers of the yeast. Strains from the probiotic capsules and the clinical isolates were identified as S. cerevisiae, with identical DNA fingerprinting. Discontinuation of use of the product in the unit stopped the outbreak of infection. A review of the literature identified another 57 cases of S. cerevisiae fungemia. Overall, 60% of these patients were in the ICU, and 71% were receiving enteral or parenteral nutrition. Use of probiotics was detected in 26 patients, and 17 patients died.


CONCLUSIONS
Use of S. cerevisiae probiotics should be carefully reassessed, particularly in immunosuppressed or critically ill patients.
3958886
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.
35809773
Candida infection of the central nervous system following neurosurgery: a 12-year review
BackgroundCandida infection of the central nervous system (CNS) following neurosurgery is relatively unusual but is associated with significant morbidity and mortality. We present our experience with this infection in adults and discuss clinical characteristics, treatment options, and outcome.MethodsAll episodes of Candida isolated from the central nervous system were identified by searching our laboratory database. Review of the cases was performed by means of a retrospective chart review.ResultsEleven episodes of Candida CSF infection following neurosurgery were identified over a 12-year period. Candida albicans was the predominant species isolated (n = 8, 73%). All infections were associated with foreign intracranial material, nine with external ventricular drains (82%), one with a ventriculoperitoneal shunt, one with a lumbar drain, and one with Gliadel wafers (1,3-bis [2-chloroethyl]-1-nitrosurea). Fluconazole or liposomal amphotericin B were the most common anti-fungal agents used. The mortality rate identified in our series was 27%.ConclusionsCandida infection following neurosurgery remains a relatively rare occurrence but one that causes significant mortality. These are complex infections, the management of which benefits from a close liaison between the clinical microbiologist and neurosurgeon. Prompt initiation of antifungal agents and removal of infected devices offers the best hope of a cure.
25189146
Cryptococcal ventriculoperitoneal shunt infection
The standard treatment of hydrocephalus is placement of a ventriculoperitoneal (VP) shunt. While infection is a common complication, rarely are fungal organisms implicated. Cryptococcus neoformans has been reported in only nine cases of shunt infection to our knowledge. The timing from shunt placement to symptom onset varies widely from 10 days to 15 months. We present a patient who developed a cryptococcal infection of his VP shunt more than two decades following shunt placement.