Phenotypic and molecular identification of Coccidioides posadasii in a patient evaluated for bilateral lung transplantation

BackgroundCoccidioidomycosis is an endemic fungal infection caused by Coccidioides immitis and Coccidioides posadasii. It can be particularly severe in transplant recipients that have a current or a previous coccidioidal infection. Fatal case of coccidioidomycosis has been described in this group of patients.AimsWe report a severe case of pneumonia caused by C. posadassi in a 29 year-old white woman that had been admitted to hospital as part of the evaluation for bilateral lung transplantation. The patient was a native and resident of Catamarca, Argentina. Molecular methodologies contributed to the species identification.MethodsClinical, laboratory records and microbiological tests were carried out to diagnose the infection and to identify C. posadasii.ResultsA fungus was isolated from BAL culture. Phenotypic characterization, specific PCR and experimental animal inoculation demonstrated the presence of C. posadasii. The patient responded well to amphotericin B deoxycholate. Lung transplantation was postponed.ConclusionsSpecific PCR can be an important alternative for the correct identification of C. immitis or C. posadasii in laboratories with implemented molecular biology tools. This case emphasizes the need for a systematic assessment in organ transplant units of patients inhabiting endemic areas of coccidioidomycosis.     

Coccidioides Endospores and Spherules Draw Strong Chemotactic,Adhesive, and Phagocytic Responses by Individual Human Neutrophils

Coccidioides spp. are dimorphic pathogenic fungi whose parasitic forms cause coccidioidomycosis (Valley fever) in mammalian hosts. We use an innovative interdisciplinary approach to analyze one-on-one encounters between human neutrophils and two forms of Coccidioides posadasii. To examine the mechanisms by which the innate immune system coordinates different stages of the host response to fungal pathogens, we dissect the immune-cell response into chemotaxis, adhesion, and phagocytosis. Our single-cell technique reveals a surprisingly strong response by initially quiescent neutrophils to close encounters with C. posadasii, both from a distance (by complement-mediated chemotaxis) as well as upon contact (by serum-dependent adhesion and phagocytosis). This response closely resembles neutrophil interactions with Candida albicans and zymosan particles, and is significantly stronger than the neutrophil responses to Cryptococcus neoformans, Aspergillus fumigatus, and Rhizopus oryzae under identical conditions. The vigorous in vitro neutrophil response suggests that C. posadasii evades in vivo recognition by neutrophils through suppression of long-range mobilization and recruitment of the immune cells. This observation elucidates an important paradigm of the recognition of microbes, i.e., that intact immunotaxis comprises an intricate spatiotemporal hierarchy of distinct chemotactic processes. Moreover, in contrast to earlier reports, human neutrophils exhibit vigorous chemotaxis toward, and frustrated phagocytosis of, the large spherules of C. posadasii under physiological-like conditions. Finally, neutrophils from healthy donors and patients with chronic coccidioidomycosis display subtle differences in their responses to antibody-coated beads, even though the patient cells appear to interact normally with C. posadasii endospores.     

Gene exchange between two divergent species of the fungal human pathogen,Coccidioides

The fungal genus Coccidioides is composed of two species, Coccidioides immitis and Coccidioides posadasii. These two species are the causal agents of coccidioidomycosis, a pulmonary disease also known as valley fever. The two species are thought to have shared genetic material due to gene exchange in spite of their long divergence. To quantify the magnitude of shared ancestry between them, we analyzed the genomes of a population sample from each species. Next, we inferred what is the expected size of shared haplotypes that might be inherited from the last common ancestor of the two species and find a cutoff to find what haplotypes have conclusively been exchanged between species. Finally, we precisely identified the breakpoints of the haplotypes that have crossed the species boundary and measure the allele frequency of each introgression in this sample. We find that introgressions are not uniformly distributed across the genome. Most, but not all, of the introgressions segregate at low frequency. Our results show that divergent species can share alleles, that species boundaries can be porous, and highlight the need for a systematic exploration of gene exchange in fungal species.     

Valley fever: danger lurking in a dust cloud

Coccidioides immitis and Coccidioides posadasii contribute to the development of Valley Fever. The ability of these fungal pathogens to evade the host immune system creates difficulty in recognition and treatment of this debilitating infection. In this review, we describe the current knowledge of Valley Fever and approaches to improve prevention, detection, and treatment.     

Proteogenomic Re‐Annotation of Coccidioides posadasii Strain Silveira

The aims of this study are to provide protein‐based evidence upon which to reannotate the genome of Coccidiodes posadasii, one of two closely related species of Coccidioides, a dimorphic fungal pathogen that causes coccidioidomycosis, also called Valley fever. Proteins present in lysates and filtrates of in vitro grown mycelia and parasitic phase spherules from C. posadasii strain Silveira are analyzed using a GeLC‐MS/MS method. Acquired spectra are processed with a proteogenomics workflow comprising a Silveira proteome database, a six‐frame translation of the Silveira genome and an ab initio gene prediction tool prior to validation against published ESTs. This study provides evidence for 837 genes expressed at the protein level, of which 169 proteins (20.2%) are putative proteins and 103 (12.3%) are not annotated in the Silveira genome. Additionally, 275 novel peptides are derived from intragenic regions of the genome and 13 from intergenic regions, resulting in 172 gene refinements. Additionally, we are the first group to report translationally active retrotransposon elements in a Coccidioides spp. Our study reveals that the currently annotated genome of C. posadasii str. Silveira needs refinement, which is likely to be the case for many nonmodel organisms.     

Update on the Epidemiology of Coccidioidomycosis

Coccidioidomycosis is an illness caused by the soil-dwelling, dimorphic fungi, Coccidioides immitis and Coccidioides posadasii, which are found primarily in niche ecological zones of the Western Hemisphere. The bulk of infections due to Coccidioides are found within the endemic areas of Arizona, California, Mexico, and Central America. Outcomes run the gamut from asymptomatic to a self-limited or even chronic pulmonary process, up to severe disseminated, and life-threatening disease. Patients at particular risk include the elderly, pregnant women, and members of certain ethnicities. Recent changes in the epidemiology and our overall understanding of coccidioidomycosis that pose a particular challenge to healthcare professionals include the rising incidence of disease, identification of infections thought to be acquired outside the previously described zones of endemicity, and the risks posed to the immunosuppressed population due to the increasing use of immunomodulatory pharmaceutical agents.     

How I Treat Coccidioidomycosis

Coccidioides immitis and C. posadasii are pathogenic dimorphic fungi responsible for causing coccidioidomycosis in the southwestern part of United States. Incidence of this disease continues to rise in endemic areas. Coccidioidomycosis starts as a respiratory illness and in less than 5 % of cases disseminates to other anatomic sites. Patient management requires careful periodic assessment. Some patients require no therapy, while others require antifungal medications for several months, or in some cases, indefinitely. Factors that influence the decision to treat include degree and duration of patient symptoms, radiographic findings, anti-complementary titers, immunosuppression and comorbidites. Cure for disseminated infection appears to be an unreachable goal with current treatments.     

Combining Forces - The Use of Landsat TM Satellite Imagery,Soil Parameter Information,and Multiplex PCR to Detect Coccidioides immitis Growth Sites in Kern County,California

Coccidioidomycosis is a fungal disease acquired through the inhalation of spores of Coccidioides spp., which afflicts primarily humans and other mammals. It is endemic to areas in the southwestern United States, including the San Joaquin Valley portion of Kern County, California, our region of interest (ROI). Recently, incidence of coccidioidomycosis, also known as valley fever, has increased significantly, and several factors including climate change have been suggested as possible drivers for this observation. Up to date details about the ecological niche of C. immitis have escaped full characterization. In our project, we chose a three-step approach to investigate this niche: 1) We examined Landsat-5-Thematic-Mapper multispectral images of our ROI by using training pixels at a 750 m×750 m section of Sharktooth Hill, a site confirmed to be a C. immitis growth site, to implement a Maximum Likelihood Classification scheme to map out the locations that could be suitable to support the growth of the pathogen; 2) We used the websoilsurvey database of the US Department of Agriculture to obtain soil parameter data; and 3) We investigated soil samples from 23 sites around Bakersfield, California using a multiplex Polymerase Chain Reaction (PCR) based method to detect the pathogen. Our results indicated that a combination of satellite imagery, soil type information, and multiplex PCR are powerful tools to predict and identify growth sites of C. immitis. This approach can be used as a basis for systematic sampling and investigation of soils to detect Coccidioides spp.     

Immunohistochemical Cross-Reactivity Between <Emphasis Type="Italic">Paracoccidioides</Emphasis> sp. from Dolphins and <Emphasis Type="Italic">Histoplasma capsulatum</Emphasis>

Paracoccidioidomycosis ceti is a cutaneous disease of cetaceans caused by uncultivated Paracoccidioides brasiliensis or Paracoccidioides spp. Serological cross-reactions between paracoccidioidomycosis ceti and paracoccidioidomycosis, paracoccidioidomycosis and histoplasmosis, and paracoccidioidomycosis and coccidioidomycosis have been reported before. The present study aimed to detect immunohistochemical cross-reaction between antibodies to Paracoccidioides sp. and Histoplasma capsulatum, and vice versa. Thirty murine sera, obtained from experimental infections of 6 isolates of H. capsulatum, were reacted with paraffin-embedded yeast-form cells of Paracoccidioides sp. derived from a case of paracoccidioidomycosis ceti in Japan. The murine sera were also reacted with human isolates of H. capsulatum yeast cells, with P. brasiliensis yeast cells, and with fungal cells of Coccidioides posadasii. Three dolphins’ sera from cases of paracoccidioidomycosis ceti, two human sera from patients with paracoccidioidomycosis, and a serum from a healthy person with a history of coccidioidomycosis were used in order to determine that the tested fungal cells reacted properly. Sera derived from mice infected with an isolate of H. capsulatum reacted positively against yeast cells of Paracoccidioides sp., yeast cells of P. brasiliensis, and fungal cells of C. posadasii, while those derived from other strains were negative. The present study recorded for the first time the cross-reaction between the yeast cells of H. capsulatum and antibodies against Paracoccidioides spp., the yeast cells of Paracoccidioides sp. and antibodies against H. capsulatum, the yeast cells of Paracoccidioides sp. and antibodies against Coccidioides sp., and fungal cells of C. posadasii and antibodies against Paracoccidioides spp.     

Blastomyces cerolytica (sp. n.) and its relation to Coccidioides

Summary In 1949 I discovered a yeast like fungus which was termedBlastomyces cerolytica. During the essay for exact determination of this fungus, it was found that it resemblesCoccidioides. Its yeast-like form is zymatic, malto-saccharasic. As organs of fructification aleurospores and chlamydospores were found, as well as asci containing hundreds af ascospores. It shows isogame heterothallism. It belongs to Taphrinales. A comparison between characteristics ofCoccidioides immitis andBlastomyces cerolytica is given. The diagnosis of this fungus concludes the investigation.

---

Resumé En 1949 nous avons découvert un champignon levuriforme, lequel nous avons nomméBlastomyces cerolytique. Il nous a paru d'être très semblable au genreCoccidioides. Son état levuriforme se comporte comme une levure zymatique et malto-saccharasique. Les formes asexuelles sont des aleurospores et des chlamydospores et les formes sexuelles des asques géants remplis de centaines d'ascospores. Il paraît être isogame hétérothallique. Il appartient à des Taphrinales. Une comparaison était mise en vue des caractéristiques deCoccidioides immitis et deBlastomyces cerolytique. Nous donnons aussi une diagnose pour ce champignon.

     

Subclinical Dissemination of Coccidioidomycosis in a Liver Transplant Recipient

Coccidioidomycosis is common in the southwestern United States, northern Mexico, and areas of South America. Coccidioides immitis and Coccidioides posadasii form arthroconidia that, if inhaled, can cause respiratory infection. Rarely, the organism disseminates throughout the body, causing disease in bones, lymph nodes, skin, joints, and brain in most severe cases. Certain populations are at higher risk for dissemination, including persons with compromised cellular immunity. This group includes patients with human immunodeficiency virus, patients undergoing immunosuppression for rheumatologic disorders, and patients receiving antirejection therapy after organ transplant. For patients undergoing a solid organ transplant in endemic areas, screening for past or present coccidioidal disease is completed pretransplantation. Those with known disease are given triazole therapy to prevent reactivation of disease posttransplantation. Usually, transplantation is postponed if the disease is active. We present a patient with known, active coccidioidomycosis who underwent successful liver transplant and later had subclinical posttransplantation peritoneal dissemination.     

Strategies to Combat Coccidioidomycosis: Are We Making Any Progress?

Coccidioidomycosis is caused by the dimorphic fungi Coccidioides immitis and Coccidioides posadasii. One of the endemic mycoses, this organism has been found solely in the semiarid to arid life zones of the southwestern United States, Mexico, and parts of Central America and South America. Clinical manifestations of disease vary greatly between patients and are largely dependent upon both the extent of exposure and the immune status of the host. The incidence of coccidioidomycosis continues to rise within the United States. Primary coccidioidal pneumonia accounts for close to 25% of all community-acquired pneumonia within endemic regions, reflecting the substantial burden of disease and health care costs associated with this infection. Although most patients with coccidioidomycosis resolve their initial infection without long-term complications, a minority of patients develop complications of disease ranging from asymptomatic pulmonary nodules to life-threatening disease such as meningitis. This review focuses on the epidemiology, clinical manifestations, spectrum of disease, and treatment options currently available for coccidioidomycosis.     

Primary Cutaneous Coccidioidomycosis in an Italian Nun Working in South America and Review of Published Literature

Coccidioidomycosis is a systemic disease caused by the dimorphic fungus Coccidioides, endemic in parts of the Southwestern USA and Central and South America. Two species, Coccidioides immitis and Coccidioides posadasii, were differentiated. Primary cutaneous coccidioidomycosis (PCC) has been reported rarely. An unusual case of PCC characterized by a persistent solitary lesion diagnosed in Italy in an immunocompetent Italian nun living in Argentina is described. The isolate was identified by sequence analysis as C. posadasii. Antibody screening was negative. A total of 39 cases of PCC have been reported in the literature. Infections occurred as a consequence of traumatic implantation in a natural setting in endemic areas or of accidental inoculation in laboratory workers. Importance of accurate investigation of travel history and of occupational hazards to laboratory workers is outlined.     

The Utility of <Emphasis Type="Italic">Coccidioides</Emphasis> Polymerase Chain Reaction Testing in the Clinical Setting

Coccidioidomycosis, the fungal infection caused by dimorphic Coccidioides sp., is typically diagnosed by histopathologic identification of spherules in affected secretions and tissues or by culture. These tests are reliable but time-intensive, delaying diagnosis and treatment. To evaluate a polymerase chain reaction (PCR) test developed to detect Coccidioides sp. in clinical specimens, we conducted a retrospective chart review of all patients (N = 145) who underwent Coccidioides PCR at our institution between April 27, 2007, and May 6, 2008, abstracting clinical, microbiologic, serologic, radiographic, treatment, and follow-up data. One hundred fifty-eight PCR tests (153 respiratory; 5 cerebrospinal fluid) produced 5 positive and 153 negative findings. Five of nine patients (56%) with confirmed or highly probable pulmonary coccidioidomycosis had a positive PCR on respiratory specimens, and four of nine (44%) had a positive culture. Among two patients with coccidioidal meningitis, none had a positive PCR, whereas Coccidioides sp. in fungal culture grew for one of two. Among six asymptomatic patients with probable coccidioidomycosis, none had a positive culture or PCR. Compared with culture of respiratory specimens, PCR demonstrated a sensitivity, specificity, positive predictive value, and negative predictive value of 75, 99, 60, and 99%, respectively. Coccidioides PCR appears accurate in identifying negative results, and its sensitivity is similar to that of fungal culture.     

Starter unit specificity directs genome mining of polyketide synthase pathways in fungi

Search of the protein database with the aflatoxin pathway polyketide synthase (PKS) revealed putative PKSs in the pathogenic fungi Coccidioides immitis and Coccidioides posadasii that could require partnerships with a pair of fatty acid synthase (FAS) subunits for the biosynthesis of fatty acid-polyketide hybrid metabolites. A starter unit:acyl-carrier protein transacylase (SAT) domain was discovered in the nonreducing PKS. This domain is thought to accept the fatty acid product from the FAS to initiate polyketide synthesis. We expressed the C. immitis SAT domain in Escherichia coli and showed that this domain, unlike that from the aflatoxin pathway PKS, transferred octanoyl-CoA four times faster than hexanoyl-CoA. The SAT domain also formed a covalent octanoyl intermediate and transferred this group to a free-standing ACP domain. Our results suggest that C. immitis/posadasii, both human fungal pathogens, contain a FAS/PKS cluster with functional similarity to the aflatoxin cluster found in Aspergillus species. Dissection of the PKS and determination of in vitro SAT domain specificity provides a tool to uncover the growing number of similar sequenced pathways in fungi, and to guide elucidation of the fatty acid-polyketide hybrid metabolites that they produce.     

Coccidioidomycosis and blastomycosis: Advances in molecular diagnosis

Clinical isolates of Coccidioides spp. and Blastomyces dermatitidis can be identified by chemiluminescent DNA probes and PCR assays targeting multicopy genes. In fixed tissue samples, cells of the two fungi are specified by in situ hybridization and PCR assays targeting 18S rDNA but sequencing of the products is mandatory. Nested PCR assays targeting genes encoding species- or genus-specific proteins like proline rich antigen of Coccidioides spp. and B. dermatitidis adhesin facilitate amplification of specific DNA from fixed tissue samples. The value of DNA amplification from native specimens of suspected cases of coccidioidomycosis or blastomycosis still needs to be determined.