Comparison of coccidioidal complement fixation and quantitative immunodiffusion serology at a reference laboratory

The incidence of coccidioidomycosis continues to increase. The diagnosis frequently relies on non-invasive diagnostic testing with immunodiffusion and complement fixation (CF) testing the current gold standard. A direct comparison of quantitative immunodiffusion and CF for IgG antibodies has not been previously reported. In a comparison of 368 samples, there was close concordance observed (360/368 = 97.8%) (P-value < .001). These tests can be considerably interchangeable in the reference laboratory setting.

Coccidioides spp. exposure among military working dogs in endemic regions of the United States

Coccidioidomycosis is a fungal disease in arid regions of the United States that is predicted to expand with climate change. Cases in military personnel and military working dogs (MWDs) impact personnel readiness and result in healthcare costs. To examine Coccidioides exposure among MWDs, 276 banked serum samples were retrieved from dogs housed in California, Texas, Arizona, New Mexico, Nevada, and Utah. Using gel immunodiffusion, six (2.1%) specimens were IgG-positive and three (1.1%) were equivocally IgM-positive. The IgG-positive samples were from Arizona (2 [prevalence 8.0%]) and California (4 [3.7%]). These data will guide future efforts to study MWDs as sentinels for human coccidioidomycosis.

Serologic Rebound after Stopping Azoles for Primary Pulmonary Coccidioidomycosis: A Case-Controlled Observational Study

BACKGROUND

We sought to characterize the outcomes of patients with primary pulmonary coccidioidomycosis whose post-treatment complement fixation (CF) titer increased by more than 2 dilutions (serologic rebound) after discontinuation of antifungal treatment.

METHODS

We conducted a retrospective chart review of patients with primary pulmonary coccidioidomycosis and identified immunocompetent, non-pregnant adults who received antifungal treatment and then experienced a serologic rebound after treatment discontinuation. We compared these to matched controls similarly treated who did not have serologic rebound.

RESULTS

Fifty-eight patients experienced serologic rebound. Thirty (52%) of these were associated with symptoms. Nine were associated with radiographic progression. The median time to serologic rebound was 3.5 months. Antifungal treatment was reinitiated in 37 (63.7%) patients. Four of the 58 (6.9%) with rebounded serology subsequently developed extra-thoracic dissemination. Compared with matched controls, patients with rebounded serology were more likely to have post-treatment symptoms, reinitiation of antifungal therapy, and a longer duration of clinical follow-up. However, they were not more likely to experience extra-thoracic dissemination.

CONCLUSION

Serological rebound, manifested in at least 2-dilution rise of CF titer following antifungal treatment of primary pulmonary coccidioidomycosis, was uncommon, but resulted in longer clinical follow-up. Continued monitoring of such patients is important to identify the patients who develop subsequent symptoms, as well as extra-thoracic dissemination.

Coccidioidomycosis: A Contemporary Review

Coccidioidomycosis, colloquially known as Valley Fever, is an invasive dimorphic fungal infection caused by Coccidioides immitis and C. posadasii. The fungi are found in the arid desert soils of the southwestern US, as well as in parts of Mexico and Central and South America. Acquisition is typically via inhalation of arthroconidia which become airborne after both natural (e.g., earthquakes, dust storms, and fires) and human-related events (e.g., military maneuvers, recreational activities, agriculture, and construction). The incidence of infection in increasing likely a result of both climatic and populational changes. Further, the recognized geographic distribution of Coccidioides spp. is expanding, as cases are being diagnosed in new areas (e.g., eastern Washington, Oregon, and Utah). Most coccidioidal infections are asymptomatic (60%); however, approximately one-third develop a pulmonary illness which is a leading cause of community-acquired pneumonia in highly endemic areas. Uncommonly (0.5–2% of cases), the infection disseminates to extrapulmonary locations (e.g., skin, bones/joints, and the central nervous system), and is most commonly seen among persons with cellular immunodeficiencies (e.g., transplant recipients, HIV, and pregnancy) and non-Caucasian races (especially African Americans and Filipinos). The diagnosis of coccidioidomycosis requires astute clinical suspicion and laboratory findings, including positive serology, cultures, and/or histopathology results. Treatment is warranted among persons with pneumonia who have risk factors for complicated disease and among those with extrapulmonary disease. Novel antifungals with improved fungicidal activity and rapidity of action with fewer side effects and drug interactions are needed. Preventive strategies (e.g., education regarding the disease, dust avoidance, mask wearing, including among select groups, antifungal prophylaxis, and surveillance laboratory testing) are advised for residents and travelers to endemic areas. Currently, no preventive vaccine is available. Coccidioidomycosis has been recognized for over a century, and an expanding wealth of knowledge has been gained regarding this emerging infectious disease which will be reviewed here.

Development of a Quantitative Antigen Assay to Detect Coccidioidal Chitinase-1 (CTS1) in Human Serum

Background

Coccidioidomycosis is often diagnosed with a collection of tests that rely on the patient's ability to mount an immune response to the fungus (antibody-based diagnostics), making diagnosis of this infection challenging. Here we present an antigen-based assay that detects and quantifies coccidioidal chitinase-1 (CTS1) in human serum.

Methods

An inhibition-based enzyme-linked immunoassay (ELISA) was developed that utilizes a monoclonal antibody specific for coccidioidal CTS1. CTS1 was quantified in commercial antigen preparations using recombinant CTS1 as a standard. Sera from 192 individuals from an endemic area were tested, which included 78 patients (40.6%) with proven or probable coccidioidomycosis.

Results

The quantity of CTS1 in diagnostic commercial antigen preparations from different suppliers varied. CTS1 antigenemia was detected in 87.2% of patients with proven or probable coccidioidomycosis. Specificity was determined to be 96.94% using serum from individuals who reside in the Phoenix, Arizona area who did not have coccidioidomycosis. Levels of CTS1 correlated with low- and high-titer serology from patients with a coccidioidomycosis diagnosis.

Conclusions

Since the CTS1 inhibition ELISA described in this report does not depend on the host immune response, it is a promising diagnostic tool to aid in diagnosis and disease monitoring of coccidioidomycosis.

Treatment for Early, Uncomplicated Coccidioidomycosis: What Is Success?

The care of primary pulmonary coccidioidomycosis remains challenging. Such infections produce a variety of signs, symptoms, and serologic responses that cause morbidity in patients and concern in treating clinicians for the possibility of extrapulmonary dissemination. Illness may be due to ongoing fungal growth that produces acute inflammatory responses, resulting in tissue damage and necrosis, and for this, administering an antifungal drug may be of benefit. In contrast, convalescence may be prolonged by other immunologic reactions to infection, even after fungal replication has been arrested, and in those situations, antifungal therapy is unlikely to yield clinical improvement. In this presentation, we discuss what findings are clinical indicators of fungal growth and what other sequelae are not. Understanding these differences provides a rational management strategy for deciding when to continue, discontinue, or reinstitute antifungal treatments.

Comparison of a Novel Rapid Lateral Flow Assay to Enzyme Immunoassay Results for Early Diagnosis of Coccidioidomycosis

BACKGROUND

Coccidioidomycosis (CM) is a common cause of community acquired pneumonia (CAP) where CM is endemic. Manifestations include self-limited pulmonary infection, chronic fibrocavitary pulmonary disease, and disseminated coccidioidomycosis (DCM). Most infections are identified by serological assays including enzyme-linked immunoassay (EIA), complement fixation (CF) and immunodiffusion (IMDF). These are time-consuming and take days to result, impeding early diagnosis. A new lateral flow assay (LFA, Sōna, IMMY, Norman OK) improves time-to-result to one hour.

METHODS

We prospectively enrolled 392 suspected CM patients, compared the LFA to standard EIA and included procalcitonin evaluation.

RESULTS

Compared to standard EIA, LFA demonstrates 31% sensitivity (95% CI of 20%-44%) and 92% specificity (95% CI of 88%-95%). Acute pulmonary disease (74%) was the most common clinical syndrome. Hospitalized patients constituted 75% of subjects, and compared to outpatients, they more frequently had ≥ 3 previous healthcare facility visits (p = 0.05), received antibacterials (p & 0.01) and had > 3 antibacterial courses (p & 0.01). Procalcitonin (PCT) was &0.25 ng/ml in 52 (83%) EIA+ patients, suggesting infection was not bacterial.

CONCLUSIONS

When CM is a possible diagnosis, LFA identified nearly a third of EIA+ infections. Combined with PCT &0.25 ng/ml, LFA could reduce unnecessary antibacterial use by 77%.

Current Concepts and Future Directions in the Pharmacology and Treatment of Coccidioidomycosis

Coccidioidomycosis remains a significant clinical problem with substantial morbidity and mortality. The vast majority of infections are asymptomatic and the need for early primary therapy remains controversial. The use of triazole antifungals has improved tolerability of therapy but concerns about acute and long-term toxicities among available agents limit their use. In addition, recent findings of decreased in vitro fluconazole susceptibility to as many as 37% of Coccidioides spp. isolates raises concerns regarding optimal therapy for these infections as fluconazole is commonly used for therapy including central nervous system disease. Thus, new agents from novel antifungal classes are currently in preclinical and clinical development aimed at reducing toxicity and improving outcomes of these serious infections.

Coccidioidomycosis Complement Fixation Titer Trends in the Age of Antifungals

Coccidioidomycosis is associated with a broad spectrum of illness severity, ranging from asymptomatic or self-limited pulmonary infection to life-threatening manifestations of disseminated disease. Serologic studies before the widespread availability of antifungals established current understanding of serologic kinetics and dynamics.

Coccidioidomycosis is associated with a broad spectrum of illness severity, ranging from asymptomatic or self-limited pulmonary infection to life-threatening manifestations of disseminated disease. Serologic studies before the widespread availability of antifungals established current understanding of serologic kinetics and dynamics. Chart histories and complement fixation (CF) titer trends were analyzed for 434 antifungal-treated coccidioidomycosis patients, who were classified by three infectious disease physicians as having either pulmonary uncomplicated coccidioidomycosis (PUC) (n = 248), pulmonary chronic coccidioidomycosis (PCC) (n = 64), disseminated coccidioidomycosis (DC) not including meningitis (n = 86), or coccidioidal meningitis (CM) (n = 36). The median maximal CF titers were 1:4 for PUC patients, 1:24 for PCC patients, 1:128 for DC patients, and 1:32 for CM patients. Approximately 25.4% of PUC patients, 6.2% of PCC patients, 2.3% of DC patients, and 8.3% of CM patients did not develop detectable titers during the study period. Maximal titers developed a mean of 31 days (95% confidence interval [CI], 13 to 50 days) after initial serologic positivity, with no significant differences between groups. Serologic recurrence occurred in 9% of PUC patients, 36% of PCC patients, 50% of DC patients, and 52% of CM patients. Median titer improvement rates were 91 days/dilution for PUC patients, 112 days/dilution for PCC patients, 136 days/dilution for DC patients, and 146 days/dilution for CM patients. Receiver operating characteristic (ROC) analysis revealed that CF testing retains moderate classification value for disseminated infections (area under the curve [AUC], 0.82 [95% CI, 0.78 to 0.87]) and complicated infections (AUC, 0.82 [95% CI, 0.77 to 0.86]). A suitable cutoff value for complicated infections is ≥1:32. Findings update serologic parameters that are relevant for clinical assessment of coccidioidomycosis patients in the triazole era.

Top Questions in the Diagnosis and Treatment of Coccidioidomycosis

Revised and greatly expanded treatment guidelines for coccidioidomycosis were published last year by the Infectious Diseases Society of America. We have selected 4 questions that commonly arise in the management of patients suspected of this disease and for which there remain divided opinions.

2016 Infectious Diseases Society of America (IDSA) Clinical Practice Guideline for the Treatment of Coccidioidomycosis

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. Infectious Diseases Society of America considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.Coccidioidomycosis, also known as San Joaquin Valley fever, is a systemic infection endemic to parts of the southwestern United States and elsewhere in the Western Hemisphere. Residence in and recent travel to these areas are critical elements for the accurate recognition of patients who develop this infection. In this practice guideline, we have organized our recommendations to address actionable questions concerning the entire spectrum of clinical syndromes. These can range from initial pulmonary infection, which eventually resolves whether or not antifungal therapy is administered, to a variety of pulmonary and extrapulmonary complications. Additional recommendations address management of coccidioidomycosis occurring for special at-risk populations. Finally, preemptive management strategies are outlined in certain at-risk populations and after unintentional laboratory exposure.

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.

Characteristics of patients with mild to moderate primary pulmonary coccidioidomycosis

In Arizona, USA, primary pulmonary coccidioidomycosis accounts for 15%-29% of community-acquired pneumonia. To determine the evolution of symptoms and changes in laboratory values for patients with mild to moderate coccidioidomycosis during 2010-2012, we conducted a prospective 24-week study of patients with primary pulmonary coccidioidomycosis. Of the 36 patients, 16 (44%) were men and 33 (92%) were White. Median age was 53 years, and 20 (56%) had received antifungal treatment at baseline. Symptom scores were higher for patients who received treatment than for those who did not. Median times from symptom onset to 50% reduction and to complete resolution for patients in treatment and nontreatment groups were 9.9 and 9.1 weeks, and 18.7 and 17.8 weeks, respectively. Median times to full return to work were 8.4 and 5.7 weeks, respectively. One patient who received treatment experienced disseminated infection. For otherwise healthy adults with acute coccidioidomycosis, convalescence was prolonged, regardless of whether they received antifungal treatment.

Evidence assessments and guideline recommendations in Lyme disease: the clinical management of known tick bites, erythema migrans rashes and persistent disease

Evidence-based guidelines for the management of patients with Lyme disease were developed by the International Lyme and Associated Diseases Society (ILADS). The guidelines address three clinical questions - the usefulness of antibiotic prophylaxis for known tick bites, the effectiveness of erythema migrans treatment and the role of antibiotic retreatment in patients with persistent manifestations of Lyme disease. Healthcare providers who evaluate and manage patients with Lyme disease are the intended users of the new ILADS guidelines, which replace those issued in 2004 (Exp Rev Anti-infect Ther 2004;2:S1-13). These clinical practice guidelines are intended to assist clinicians by presenting evidence-based treatment recommendations, which follow the Grading of Recommendations Assessment, Development and Evaluation system. ILADS guidelines are not intended to be the sole source of guidance in managing Lyme disease and they should not be viewed as a substitute for clinical judgment nor used to establish treatment protocols.

Recent advances in our understanding of the environmental, epidemiological, immunological, and clinical dimensions of coccidioidomycosis

Coccidioidomycosis is the endemic mycosis caused by the fungal pathogens Coccidioides immitis and C. posadasii. This review is a summary of the recent advances that have been made in the understanding of this pathogen, including its mycology, genetics, and niche in the environment. Updates on the epidemiology of the organism emphasize that it is a continuing, significant problem in areas of endemicity. For a variety of reasons, the number of reported coccidioidal infections has increased dramatically over the past decade. While continual improvements in the fields of organ transplantation and management of autoimmune disorders and patients with HIV have led to dilemmas with concurrent infection with coccidioidomycosis, they have also led to advances in the understanding of the human immune response to infection. There have been some advances in therapeutics with the increased use of newer azoles. Lastly, there is an overview of the ongoing search for a preventative vaccine.

Detection of microorganisms in granulomas that have been formalin-fixed: review of the literature regarding use of molecular methods

Granuloma is an organized aggregate of immune cells that under the microscope appear as epithelioid macrophages. A granuloma can only be diagnosed when a pathologist observes this type of inflammation under the microscope. If a foreign body or a parasite is not observed inside the granuloma, stains for acid-fast bacilli and fungi are ordered since mycobacteria and fungi are frequently the cause of this type of inflammation. It is calculated that 12 to 36% of granulomas do not have a specific etiology and many have wondered if with new molecular methods we could reduce this number. This paper will summarize the frequently known causes of granulomas and will present the recent literature regarding the use of molecular techniques on tissue specimens and how these have helped in defining causative agents. We will also briefly describe new research regarding formation and function of granulomas and how this impacts our ability to find an etiologic agent.

Clinical specificity of the enzyme immunoassay test for coccidioidomycosis varies according to the reason for its performance

The diagnosis of coccidioidomycosis relies heavily on serologic test results in addition to clinical history, physical examination, and radiographic findings. Use of the enzyme immunoassay (EIA) has increased because it is rapidly performed and does not require referral to a reference laboratory, as do complement fixation and immunodiffusion tests. However, interpretation of immunoglobulin M (IgM) reactivity by EIA in the absence of immunoglobulin G (IgG) reactivity has been problematic. We conducted a retrospective medical record review of all patients with such IgM reactivity at our institution to identify situations where the finding was more likely to be clinically specific for coccidioidal infection. From 1 January 2004 through 31 December 2008, a total of 1,117 patients had positive EIA coccidioidal serology or EIA IgM-only reactivity; of these, 102 patients (9%) had EIA IgM-only reactivity. Among the 102 patients with EIA IgM-only reactivity, 60 were tested to evaluate symptomatic illness, 13 for follow-up of previously abnormal serology, and 29 for screening purposes. Of the 102 patients, 80 (78%) had positive serologic findings by other methods or had positive culture or histology. Fifty-four (90%) of the 60 patients whose serology was performed to evaluate symptomatic illness had coccidioidal infection, whereas 13 (45%) of 29 patients whose serology was performed for screening purposes had coccidioidal infection. Of the 102 patients with isolated IgM reactivity by EIA, 12 later seroconverted to IgG and IgM reactivity. The use of EIA for screening in 29 asymptomatic persons was associated with unconfirmable results in 13 (45%). Although the majority of patients in our study with isolated IgM reactivity by EIA had probable or confirmed coccidioidomycosis, this result must be interpreted with caution for asymptomatic patients.

Serum (1->3)-β-D-glucan measurement in coccidioidomycosis

The serum (1→3)-β-d-glucan assay has emerged as an important diagnostic test for invasive fungal disease. The utility of this assay in coccidioidomycosis has not been previously studied. Using a cutoff value of ≥80 pg/ml, we found the sensitivity (43.9%), specificity (91.1%), positive predictive value (81.8%), and negative predictive value (64.1%) to be similar to those of the assay in diagnosing other invasive mycoses.