Polymerase chain reaction in the diagnosis of invasive aspergillosis

Diagnosis of Infectious Diseases in the Lower Respiratory Tract: A Cytopathologist's Perspective

CONTEXT.—

Respiratory cytology continues to play an important role in the diagnosis of lower respiratory tract infections. Prompt, accurate diagnosis of causative organisms is of paramount importance, particularly in immunosuppressed patients. In addition, a rapidly expanding arsenal of ancillary testing is now available, aiding tremendously in organism identification.

OBJECTIVE.—

To provide an updated review on the cytomorphologic features of common organisms in lower respiratory tract infection. Relevant ancillary tests, differential diagnoses, and potential pitfalls of organism identification will also be discussed.

DATA SOURCES.—

Data for this review were gathered from PubMed searches of infectious diseases of the lower respiratory tract, especially related to the diagnoses.

CONCLUSIONS.—

The lower respiratory tract is subject to infection by a wide variety of infectious agents. Pathologists should be familiar with common organisms, including their general clinical characteristics, cytomorphologic features, differential diagnoses, and ancillary methods of detection. Above all, correlation with microbiologic and clinical information is necessary to make a confident diagnosis of infection.

How to treat fungal infections in ICU patients

Fungal infections represent a major burden in the critical care setting with increasing morbidity and mortality. Candidiasis is the leading cause of such infections, with C. albicans being the most common causative agent, followed by Aspergillosis and Mucormycosis. The diagnosis of such infections is cumbersome requiring increased clinical vigilance and extensive laboratory testing, including radiology, cultures, biopsies and other indirect methods. However, it is not uncommon for definitive evidence to be unavailable. Risk and host factors indicating the probability of infections may greatly help in the diagnostic approach. Timely and adequate intervention is important for their successful treatment. The available therapeutic armamentarium, although not very extensive, is effective with low resistance rates for the newer antifungal agents. However, timely and prudent use is necessary to maximize favorable outcomes.

Invasive fungal infections in the ICU: how to approach, how to treat

Invasive fungal infections are a growing problem in critically ill patients and are associated with increased morbidity and mortality. Most of them are due to Candida species, especially Candida albicans. Invasive candidiasis includes candidaemia, disseminated candidiasis with deep organ involvement and chronic disseminated candidiasis. During the last decades rare pathogenic fungi, such as Aspergillus species, Zygomycetes, Fusarium species and Scedosporium have also emerged. Timely diagnosis and proper treatment are of paramount importance for a favorable outcome. Besides blood cultures, several laboratory tests have been developed in the hope of facilitating an earlier detection of infection. The antifungal armamentarium has also been expanded allowing a treatment choice tailored to individual patients' needs. The physician can choose among the old class of polyenes, the older and newer azoles and the echinocandins. Factors related to patient's clinical situation and present co-morbidities, local epidemiology data and purpose of treatment (prophylactic, pre-emptive, empiric or definitive) should be taken into account for the appropriate choice of antifungal agent.

Invasive pulmonary aspergillosis in patients with COPD: a report of five cases and systematic review of the literature

BACKGROUND

There are increasing reports describing invasive pulmonary aspergillosis (IPA) in patients with chronic obstructive pulmonary disease (COPD) without the classic risk factors for this severe infection. The available literature on this association is based on case reports or small case series. The aim of this review is to systematically review these cases and describe the clinical features, diagnostic studies and outcome.

METHODS

We identified all the cases of IPA and COPD reported in the literature and had enough clinical information. We also included five cases of IPA in patients with COPD identified by the authors. These cases were systematically reviewed for clinical features, diagnostic studies and outcome.

RESULTS

There were 60 cases of IPA in patients with COPD identified from the literature. The total number of cases reviewed was 65. The mean age was 65.1 years, the mean FEV1 was 39% of predicted (n = 17, range 19-56%). Forty-nine patients were documented to be on systemic corticosteroids. The mean dose was 24 mg/day (range 15-65 mg/day). Five patients were only on inhaled corticosteroids and in 11 patients there was no documentation of corticosteroid therapy. The clinical and radiological findings were nonspecific. Thirteen patients had documented evidence of disseminated IPA. Sputum examination was positive for Aspergillus in 76% and bronchoscopy with bronchoalveolar lavage that was positive in 70%. The diagnosis of IPA was definite in 43 patients and probable in 22 patients. Forty-six patients were treated with anti-fungal therapy. Fifty-nine patients (91%) died with IPA.

CONCLUSION

Invasive pulmonary aspergillosis is an emerging serious infection in patients with COPD. The majority of these patients have advanced COPD and/or on corticosteroid therapy. The clinical and radiological presentation is nonspecific. High index of suspicion is necessary for the timely treatment of these patients.

Investigation of fungi in massive nasal polyps: microscopy, culture, polymerase-chain reaction, and serology

BACKGROUND

Although some clues exist about the causative relationship of fungi and chronic rhinosinusitis, the relationship of nasal polyps and fungi has not been enlightened. The purpose of this study was to determine whether a relationship exists between fungi and massive nasal polyps and to evaluate current available diagnostic techniques for detection of fungi.

METHODS

Thirty cases of massive nasal polyposis (NP) were evaluated prospectively for fungal evidence and were compared with 18 cases of concha bullosa based on direct microscopy, fungal culture, serology, polymerase chain reaction (PCR), and sequencing.

RESULTS

Fungal colonization was detected in 15 (50.0%) of the cases with massive NP, but only in 2 (11.1%) of the cases with concha bullosa. A significant difference was found between the study and the control groups in terms of fungal existence (p < 0.016). Direct microscopy was positive in 14 (46.7%) and 1 (5.6%) of the cases;fungal culture was positive in 8 (26.7%) and 4 (22.2%) of the cases; serology was positive in 9 (30.0%) and 2 (11.1%) of the cases; PCR was positive in 18 (60.0%) and 6 (33.3%) of the cases with massive NP and concha bullosa, respectively.

CONCLUSION

Fungal colonization was found to be more common in massive NP patients compared with the control group. According to our results, microscopy and PCR were most sensitive techniques for detection of fungi.

Evaluation of the role of real-time PCR in the diagnosis of invasive aspergillosis

Recently, two developments relating to the diagnosis of invasive aspergillosis (IA) have occurred. First, the standardisation of criteria for determining the category of this disease according to the European Organisation for Research and Treatment of Cancer/Mycosis (EORTC) Study Group consensus definitions has allowed comparison of results from different studies to be undertaken. The second development is the generation of PCR assays based on real-time technologies that are able to quantify Aspergillus DNA. In this review the benefits and limitations of these new published assays are compared with nested-PCR assays and enzyme immuno assays. Results from studies where these real-time assays have been used and patient's infections were classified according the EORTC definitions are examined. The effect of anti-fungal treatment is noted. The requirement for both international standards and a consensus protocol that is sensitive enough for IA diagnosis, particularly in blood, is discussed.