Coccidioidomycosis in persons infected with HIV-1

Musculoskeletal manifestations of lower-extremity coccidioidomycosis: a case series

Background: Coccidioidomycosis is a fungal infection endemic to the southwestern United States. Musculoskeletal manifestations are uncommon and seen in disseminated disease. While the involvement of the axial skeleton has been well described, the literature is limited on diseases involving the lower extremity. Methods: We identified three patients, at two regional academic medical centers in southern Arizona, who demonstrated different manifestations of osteoarticular coccidioidomycosis involving the lower extremity. Results: Case 1 is a 41-year-old male, with a history of HIV/AIDS and vertebral coccidioidomycosis, who presented with abscesses in the left hemipelvis and left proximal femoral osteomyelitis. He was treated with staged surgical debridement, including the use of amphotericin B impregnated beads. He remains on indefinite oral posaconazole suppression. Case 2 is a 46-year-old female, who presented with suspected right knee osteoarthritis. An MRI revealed septic arthritis and osteomyelitis. Necrotic bone was debrided, and synovial fluid cultures were positive for Coccidioides. She underwent a resection of the native knee joint with the insertion of an amphotericin B and voriconazole impregnated spacer. She continues oral itraconazole and awaits a total knee arthroplasty. Case 3 is a 76-year-old male, who presented with a draining right heel ulcer. Radiographs revealed bony destruction consistent with Charcot arthropathy. Irrigation and debridement revealed the gelatinous destruction of the talus and calcaneus, and cultures confirmed Coccidioides infection. A polymethyl methacrylate voriconazole spacer was placed. He subsequently underwent arthrodesis and remains on lifelong fluconazole. Conclusion: Lower-extremity osteoarticular coccidioidomycosis has various debilitating presentations that frequently mimic non-infectious etiologies. Treatment warrants surgical debridement, and prolonged antifungal therapy should be considered.

The mysterious desert dwellers: Coccidioides immitis and Coccidioides posadasii, causative fungal agents of coccidioidomycosis

The genus Coccidioides consists of two species: C. immitis and C. posadasii. Prior to 2000, all disease was thought to be caused by a single species, C. immitis. The organism grows in arid to semiarid alkaline soils throughout western North America and into Central and South America. Regions in the United States, with highest prevalence of disease, include California, Arizona, and Texas. The Mexican states of Baja California, Coahuila, Sonora, and Neuvo Leon currently have the highest skin test positive results. Central America contains isolated endemic areas in Guatemala and Honduras. South America has isolated regions of high endemicity including areas of Colombia, Venezuela, Argentina, Paraguay, and Brazil. Although approximately 15,000 cases per year are reported in the United States, actual disease burden is estimated to be in the hundreds of thousands, as only California and Arizona have dedicated public health outreach, and report and track disease reliably. In this review, we survey genomics, epidemiology, ecology, and summarize aspects of disease, diagnosis, prevention, and treatment.

Coccidioidomycosis in selected immunosuppressed hosts

After contracting coccidioidomycosis, persons with impaired cellular immunity are more likely than healthy persons to have severe infection, disseminated infection, and higher mortality rates. In this brief review, we summarize the clinical manifestations, diagnosis, treatment, and prevention of coccidioidomycosis in persons infected with human immunodeficiency virus (HIV), recipients of solid organ or hematopoietic stem cell transplants, and recipients of biologic response modifiers. Among individuals infected with HIV, a diagnosis of acquired immunodeficiency syndrome (AIDS) and a CD4 T-lymphocyte count <250 cells/μl were associated with more severe coccidioidomycosis, whereas less severe disease occurred among those with undetectable HIV-RNA and higher CD4 T-lymphocyte counts, indicating that controlled HIV viremia and improved cellular immune status are important in limiting disease. For transplant recipients whose immunosuppression typically peaks in the first 3 to 6 months and tapers thereafter, the greatest risk of acute coccidioidomycosis occurs 6 to 12 months after transplantation. Relapses of recent coccidioidomycosis may occur during ongoing immunosuppression when patients are not taking suppressive antifungal medication. Recipients of biologic agents, especially those that impair tumor necrosis factor α (TNF-α), may be at increased risk for poorly controlled coccidioidomycosis; however, the best way to prevent and treat such infections has yet to be defined.

Card9- and MyD88-Mediated Gamma Interferon and Nitric Oxide Production Is Essential for Resistance to Subcutaneous Coccidioides posadasii Infection

Coccidioidomycosis is a potentially life-threatening respiratory disease which is endemic to the southwestern United States and arid regions of Central and South America. It is responsible for approximately 150,000 infections annually in the United States alone. Almost every human organ has been reported to harbor parasitic cells of Coccidioides spp. in collective cases of the disseminated form of this mycosis. Current understanding of the mechanisms of protective immunity against lung infection has been largely derived from murine models of pulmonary coccidioidomycosis. However, little is known about the nature of the host response to Coccidioides in extrapulmonary tissue. Primary subcutaneous coccidioidal infection is rare but has been reported to result in disseminated disease. Here, we show that activation of MyD88 and Card9 signal pathways are required for resistance to Coccidioides infection following subcutaneous challenge of C57BL/6 mice, which correlates with earlier findings of the protective response to pulmonary infection. MyD88(-/-) andCard9(-/-) mice recruited reduced numbers of T cells, B cells, and neutrophils to the Coccidioides-infected hypodermis com pared to wild-type mice; however, neutrophils were dispensable for resistance to skin infection. Further studies have shown that gamma interferon (IFN-γ) production and activation of Th1 cells characterize resistance to subcutaneous infection. Furthermore, activation of a phagosomal enzyme, inducible nitric oxide synthase, which is necessary for NO production, is a requisite for fungal clearance in the hypodermis. Collectively, our data demonstrate that MyD88- and Card9-mediated IFN-γ and nitric oxide production is essential for protection against subcutaneous Coccidioides infection.

Clinically relevant drug-drug interactions between antiretrovirals and antifungals

INTRODUCTION

Complete delineation of the HIV-1 life cycle has resulted in the development of several antiretroviral drugs. Twenty-five therapeutic agents belonging to five different classes are currently available for the treatment of HIV-1 infections. Advent of triple combination antiretroviral therapy has significantly lowered the mortality rate in HIV patients. However, fungal infections still represent major opportunistic diseases in immunocompromised patients worldwide.

AREAS COVERED

Antiretroviral drugs that target enzymes and/or proteins indispensable for viral replication are discussed in this article. Fungal infections, causative organisms, epidemiology and preferred treatment modalities are also outlined. Finally, observed/predicted drug-drug interactions between antiretrovirals and antifungals are summarized along with clinical recommendations.

EXPERT OPINION

Concomitant use of amphotericin B and tenofovir must be closely monitored for renal functioning. Due to relatively weak interactive potential with the CYP450 system, fluconazole is the preferred antifungal drug. High itraconazole doses (> 200 mg/day) are not advised in patients receiving booster protease inhibitor (PI) regimen. Posaconazole is contraindicated in combination with either efavirenz or fosamprenavir. Moreover, voriconazole is contraindicated with high-dose ritonavir-boosted PI. Echinocandins may aid in overcoming the limitations of existing antifungal therapy. An increasing number of documented or predicted drug-drug interactions and therapeutic drug monitoring may aid in the management of HIV-associated opportunistic fungal infections.

Coccidioidomycosis: epidemiology

Coccidioidomycosis consists of a spectrum of disease, ranging from a mild, self-limited, febrile illness to severe, life-threatening infection. It is caused by the soil-dwelling fungi, Coccidioides immitis and C. posadasii, which are present in diverse endemic areas. Climate changes and environmental factors affect the Coccidioides lifecycle and influence infection rates. The incidence of coccidioidomycosis has risen substantially over the past two decades. The vast majority of Coccidioides infections occur in the endemic zones, such as California, Arizona, Mexico, and Central America. Infections occurring outside those zones appear to be increasingly common, and pose unique clinical and public health challenges. It has long been known that elderly persons, pregnant women, and members of certain ethnic groups are at risk for severe or disseminated coccidioidomycosis. In recent years, it has become evident that persons with immunodeficiency diseases, diabetics, transplant recipients, and prisoners are also particularly vulnerable.

Coccidioidomycosis incidence in Arizona predicted by seasonal precipitation

The environmental mechanisms that determine the inter-annual and seasonal variability in incidence of coccidioidomycosis are unclear. In this study, we use Arizona coccidioidomycosis case data for 1995-2006 to generate a timeseries of monthly estimates of exposure rates in Maricopa County, AZ and Pima County, AZ. We reveal a seasonal autocorrelation structure for exposure rates in both Maricopa County and Pima County which indicates that exposure rates are strongly related from the fall to the spring. An abrupt end to this autocorrelation relationship occurs near the the onset of the summer precipitation season and increasing exposure rates related to the subsequent season. The identification of the autocorrelation structure enabled us to construct a "primary" exposure season that spans August-March and a "secondary" season that spans April-June which are then used in subsequent analyses. We show that October-December precipitation is positively associated with rates of exposure for the primary exposure season in both Maricopa County (R = 0.72, p = 0.012) and Pima County (R = 0.69, p = 0.019). In addition, exposure rates during the primary exposure seasons are negatively associated with concurrent precipitation in Maricopa (R = -0.79, p = 0.004) and Pima (R = -0.64, p = 0.019), possibly due to reduced spore dispersion. These associations enabled the generation of models to estimate exposure rates for the primary exposure season. The models explain 69% (p = 0.009) and 54% (p = 0.045) of the variance in the study period for Maricopa and Pima counties, respectively. We did not find any significant predictors for exposure rates during the secondary season. This study builds on previous studies examining the causes of temporal fluctuations in coccidioidomycosis, and corroborates the "grow and blow" hypothesis.

Epidemiology of endemic systemic fungal infections in Latin America

Although endemic mycoses are a frequent health problem in Latin American countries, clinical and epidemiological data remain scarce and fragmentary. These mycoses have a significant impact on public health, and early diagnosis and appropriate treatment remain important. The target population for endemic disease in Latin America is mostly represented by low-income rural workers with limited access to a public or private health system. Unfortunately, diagnostic tools are not widely available in medical centers in Latin America; consequently, by the time patients are diagnosed with fungal infection, many are already severely ill. Among immunocompromised patients, endemic mycoses usually behave as opportunistic infections causing disseminated rather than localized disease. This paper reviews the epidemiology of the most clinically significant endemic mycoses in Latin America: paracoccidioidomycosis, histoplasmosis, and coccidioidomycosis. The burdens of disease, typically affected populations, and clinical outcomes also are discussed.

Coccidioidomycosis and tuberculosis coinfection at a tuberculosis hospital: clinical features and literature review

Tuberculosis (TB) and coccidioidomycosis can have similar clinical and radiologic presentations but require different treatments. Coinfection with TB and Coccidioides immitis is uncommonly reported and may be underdiagnosed in endemic areas.We performed a retrospective review of the medical records of all patients admitted to a TB referral hospital between 1995 and 2007, and selected all cases of TB and coccidioidomycosis coinfection in patients aged 18 years or older. All admitted patients had a diagnosis of TB and had sputum cultures for both pathogens. We reviewed clinical, laboratory, and radiologic features of the cases, and noted antimicrobial treatments received and outcomes.We identified 9 patients, of whom 7 (78%) were Hispanic. Most patients were male (8/9, 89%), and all were diagnosed with coccidioidomycosis after TB. Three (33%) patients had drug-resistant TB. Six patients had culture-positive TB at the time of the double diagnosis, and 2 patients developed active coccidioidomycosis during their hospital stay. Only 1 had human immunodeficiency virus/acquired immunodeficiency syndrome (HIV-AIDS) (CD4 count, 20 cells/mm). All but 2 patients were treated with antifungal agents. Two patients died, 1 of whom had AIDS. Radiologic studies were unable to distinguish between TB and coccidioidomycosis, except for a patient who developed a new air-fluid level in a previously stable cavity.TB and coccidioidomycosis coinfection should be suspected in coccidioidomycosis-endemic regions among patients with TB who fail to improve clinically or radiologically despite adequate, culture-directed therapy.

Diagnosis of coccidioidomycosis with use of the Coccidioides antigen enzyme immunoassay

BACKGROUND

We have previously shown antigenuria in patients with coccidioidomycosis through use of the Histoplasma antigen enzyme immunoassay (EIA), and now we have developed a specific Coccidioides antigen EIA.

METHODS

The Coccidioides EIA uses antibodies to Coccidioides galactomannan. The sensitivity of the Coccidioides and Histoplasma EIAs was evaluated in patients with more-severe coccidioidomycosis, and the specificity of these EIAs was evaluated in patients with nonfungal infections, in patients with other endemic mycoses, and in healthy individuals.

RESULTS

Among patients in the present study, antigenuria was detected in 70.8% of patients with coccidioidomycosis with use of the Coccidioides EIA and in 58.3% of patients with use of the Histoplasma EIA. Antigenuria was absent in 99.4% of healthy individuals, patients with nonfungal infections, and patients with noninfectious conditions. Cross-reactions with other endemic mycoses were observed in 10.7% of patients.

CONCLUSIONS

The Coccidioides EIA has potential to be useful in the rapid diagnosis of more-severe forms of coccidioidomycosis.