Candidal antigen detection in pulmonary candidiasis

Candida pneumonia with severe clinical course, recovery with antifungal therapy and unusual pathologic findings: A case report

BACKGROUND

Candida is frequently isolated from the respiratory tract and usually reflects airway colonization. True Candida pneumonia is rare. Our aim is to document a case of Candida pneumonia confirmed by cultures, molecular techniques, and surgical lung biopsy, and to highlight a previously unreported pathologic manifestation of this infection.

CASE SUMMARY

A 59-year-old man with a history of chronic obstructive pulmonary disease (COPD) presented with dry cough, low-grade fever, and progressive dyspnea. He was eventually diagnosed with sarcoidosis based on bilateral lung infiltrates and granulomas in a transbronchial biopsy. His condition worsened after immunosuppression, prompting surgical lung biopsy, which revealed suppurative granulomas containing Candida albicans, confirmed by cultures and polymerase chain reaction. Despite multiple episodes of respiratory failure and a prolonged course in intensive care, he recovered fully after antifungal therapy and is currently alive with COPD-related dyspnea 3 years after his initial presentation.

CONCLUSION

Candida can rarely cause clinically significant pneumonia in adults, and should be considered in the differential diagnosis of suppurative granulomas in the lung.

Candida and the paediatric lung

Although systemic candidosis is common in hospitalised children, Candida involvement of lung parenchyma is rare and usually perceived only at autopsy. The purpose of this article was to review the evidence regarding lung involvement in Candida infections, with special attention to paediatric patients. Primary Candida pneumonia is rare and usually associated with aspiration of oropharyngeal contents. The majority of cases of Candida pneumonia are secondary to haematological dissemination of Candida organisms from a distant site, usually the gastrointestinal tract or the skin. The diagnosis of pulmonary candidosis is difficult because there is no specific clinical or radiological presentation. In addition, the presence of Candida in sputum or other respiratory specimens mostly represents contamination. A definitive diagnosis of Candida pneumonia requires histopathologic proof of lung invasion in association with inflammation. Children can also be affected by pulmonary allergic reactions caused by Candida species. Treatment of Candida pneumonia is essentially the same as for candidaemia. Preliminary evidence suggests that patients with severe asthma sensitised to Candida species may also benefit from antifungal drugs.

Fungal Infections

The incidence of invasive fungal infections has increased dramatically over the past two decades, mostly due to an increase in the number of immunocompromised patients.1–4 Patients who undergo chemotherapy for a variety of diseases, patients with organ transplants, and patients with the acquired immune deficiency syndrome have contributed most to the increase in fungal infections.5 The actual incidence of invasive fungal infections in transplant patients ranges from 15% to 25% in bone marrow transplant recipients to 5% to 42% in solid organ transplant recipients.6,7 The most frequently encountered are Aspergillus species, followed by Cryptococcus and Candida species. Fungal infections are also associated with a higher mortality than either bacterial or viral infections in these patient populations. This is because of the limited number of available therapies, dose-limiting toxicities of the antifungal drugs, fewer symptoms due to lack of inflammatory response, and the lack of sensitive tests to aid in the diagnosis of invasive fungal infections.1 A study of patients with fungal infections admitted to a university-affiliated hospital indicated that community-acquired infections are becoming a serious problem; 67% of the 140 patients had community-acquired fungal pneumonia.8

Subacute primary Candida lung abscess

A case of primary subacute Candida lung abscess is described. The most reliable way to diagnose a rare pulmonary disease is to perform an open lung biopsy. A review of the literature suggests that the diagnosis of a primary subacute abscess due to Candida albicans in vivo is unique.

Community-acquired Staphylococcus epidermidis endocarditis complicated by splenic disease 9 years after aortic valve replacement

We describe here a case of Staphylococcus epidermidis prosthetic aortic valve endocarditis 9 y after valve replacement. Surprisingly, the microorganism was community-acquired, highly virulent and associated with splenic disease. The patient recovered following emergency valve replacement and prolonged antibiotic therapy. Splenectomy was not required.

Reactivity of fungal organisms in tissue sections using anti-mycobacteria antibodies

Sixty-four cases of deep fungal infections diagnosed using PAS or silver stains and 18 control cases of sarcoidosis, M. tuberculosis and M. leprae infection were stained using commercial polyclonal antibody raised against M. paratuberculosis (MP), M. Duvalii (MD), and Bacillus Calmette-Guerin (BCG). Nine of 13 cases of sporotrichosis stained positively using anti-MP antibody only; 13 of 14 cases of histoplasmosis stained with anti-BCG, anti-MD, and anti-MP; seven cases of cryptococcosis had only focal staining of rare individual organisms within masses of negative organisms; seven of eight cases of coccidioidomycosis stained predominantly with anti-BCG and anti-MP; eight cases of aspergillus had focal (1 to 5% of organisms) staining of hyphae with anti-BCG and anti-MD; and four of 12 cases of Candida infection showed focal nonspecific staining with both antibodies and nonimmune serum. Control cases of sarcoidosis exhibited no staining with any of the three antibodies, whereas cases of mycobacterial infection showed staining of bacilli and intracellular debris with all three antibodies.

Prospective evaluation of a Candida antigen detection test for invasive candidiasis in immunocompromised adult patients with cancer

PURPOSE

Serologic tests to detect invasive candidiasis generally have been unreliable. We prospectively evaluated the clinical utility of a new, promising commercial latex particle agglutination test (i.e., Cand-Tec, Ramco Laboratories, Inc., Houston, Texas). This assay detects Candida antigens in serum.

PATIENTS AND METHODS

We examined the reliability of Cand-Tec to diagnose invasive candidiasis in 142 consecutive in-patients intensively treated with chemo-radiation therapy. Serum samples were collected at admission and then weekly, until the patients' death or hospital discharge. Evaluation for clinical utility was done using various reference titers. Twenty-nine patients had invasive candidiasis whereas 113 patients did not have documented invasive candidal infections.

RESULTS

At a titer of 1:8, the Cand-Tec test had sensitivity of 38%, specificity of 90%, positive predictive value of 50%, and negative predictive value of 85%. Weekly use of the Cand-Tec test did not improve early detection of invasive candidiasis, providing only a mean interval of 0.4 day from the first positive Cand-Tec result to a definitive diagnosis of invasive candidiasis by blood culture, tissue biopsy, or autopsy. In addition, surveillance cultures from the oropharynx or stool were not helpful in identifying those patients who would develop an invasive fungal infection.

CONCLUSION

In the context of current clinical management strategies for suspected fungal infection, the Candida antigen detection assay (Cand-Tec) is not a reliable method for diagnosis of deep candidiasis in neutropenic patients. Until better methods of early detection are available, patients at high risk for the development of invasive candidiasis should continue to receive empiric antifungal agent therapy.

Detection of Candida sp. mannan antigen by indirect ELISA-inhibition. In vitro crossed reactivity among mannans obtained from C. albicans A, C. albicans B, and C. tropicalis

We have obtained mannans from four Candida species: C. albicans A, C. albicans B and C. tropicalis; anti-mannan sera against C. albicans A, C. albicans B and C. tropicalis were obtained by immunizing rabbits subcutaneously with the respective yeast extract. The efficacy of these sera in reacting with mannans obtained from three Candida sp. has been proven by indirect ELISA-inhibition. Any of three immune sera can be used to detect mannan antigen from the three Candida sp. tested. This confirms the existence of crossed reactivity and the possibility of detecting mannan antigen in serum from patients infected by different Candida sp., although we had only one immune serum and one Candida mannan.

Mycobacterial antigen detection by immunohistochemistry in pulmonary tuberculosis

A preliminary diagnosis of tuberculosis can be established by the detection of acid-fast bacilli (AFB) and confirmed by culture of the microorganism. To evaluate an alternative method of diagnosis, the distribution of mycobacterial antigens in lung tissue specimens was characterized by an indirect peroxidase-antiperoxidase method and was compared to the detection of AFB by Ziehl-Neelsen stain. Histologic specimens were obtained from 59 hospital patients. Of nine patients with mycobacterial disease, seven had antigen detected in tissue. In two patients with tuberculous pneumonia, the distribution of mycobacterial antigens was approximately the same as that of AFB. In contrast, in four patients with caseating pulmonary granulomas, clumps of mycobacterial antigens were demonstrated in necrotic areas of the granulomas where there were few or no AFB. In one patient with Mycobacterium intracellulare infection, cross-reactive antigens stained weakly. Antigen was not found in tissue from two patients; one had miliary lung granulomas, and the second had mediastinal lymph node granulomas. Mycobacterial antigens were not detected in specimens from 50 control patients with nonmycobacterial diseases. On the basis of this study of 59 cases, immunohistochemical detection of microbial antigens appears to be useful for establishing the mycobacterial etiology of caseating pulmonary granulomas.

Identification and molecular weight characterization of antigens from Candida albicans that are recognized by human sera

Antigenic components in the cytoplasmic extract of Candida albicans were examined after fractionation by concanavalin A-Sepharose and DEAE-Sephacel ion-exchange chromatography. Fractions from the DEAE column were tested by fused rocket immunoelectrophoresis for their reactivity with antibodies in the sera of 20 patients with disseminated candidiasis. Three groups of fractions (regions A, B, and C) from the DEAE column were defined by their reactivity with these sera. Immunoblot analysis with 20 human sera identified 18 antigenic components in regions A, B, and C. Region A contained nine antigens, region B contained four antigens, and region C contained five antigens. Region A contained an antigen with an apparent molecular weight of 48,000 that was recognized by 7 of 10 sera from patients with disseminated candidiasis. Immunoprecipitation experiments with labeled proteins from region A and 51 human sera also demonstrated the presence of a major antigen whose apparent molecular weight is 48,000 to 52,000. The 48- to 52-kilodalton protein is an abundant protein in region A and is the most frequently recognized protein by antibodies in the sera of patients with disseminated candidiasis. Patients with disseminated candidiasis had significantly higher levels of antibody (immunoglobulin G) (P less than 0.001) directed against the 48- to 52-kilodalton protein than did patients with noninvasive forms of candidiasis, patients with other fungal infections, or normal, healthy persons.

Antigenemia detected in human coccidioidomycosis

To advance the serological diagnosis of coccidioidomycosis, a radioimmunoassay was developed to detect an antigen of Coccidioides immitis and evaluated with serum samples from patients and controls. The assay antigen was fractionated from a culture filtrate of C. immitis cells by Sephacryl S300 gel chromatography. The assay used preliminary acid-heat extraction to dissociate serum-bound antigen and staphylococcal protein A as an absorbent. Antigenemia was detected in five (56%) of nine patients with coccidioidomycosis. Three of four negative tests occurred with sera from patients who had already received antifungal chemotherapy. Antigenemia was not detected in 106 control patients and normal donors. One false-positive reaction was observed in a patient with histoplasmosis. In all nine patients with active coccidioidomycosis, anti-C. immitis antibodies were detected during the initial evaluation or in the follow-up. In summary, an immunoassay for C. immitis antigenemia was developed; antigenemia was detected in five (56%) of nine patients with active coccidioidomycosis and a positive test indicated active or persistent disease.