Pitfalls in immunoblot detection of Aspergillus antigens associated with invasive infection

Abstract

strains of 12 species or subspecies of Campylobacter, Helicobacter, and Arcobacter were isolated from 7,680 diarrhetic stool samples. Two hundred and fifty-five (13.8%) of these isolates were dependent on H2-enhanced microaerophilic growth conditions, an essential requirement of C. concisus, C. mucosalis, C. curvus, and C. rectus (7). All 255 clinical isolates plus isolate NCTC 12408 were positive for oxidase and nitrate reductase but were negative for catalase, indoxyl acetate, hippurate, and urease. Every isolate produced abundant H2S, detectable in triple sugar iron agar and often completely blackening lead acetate strips. Isolates tolerate 1% glycine but not 3.5% NaCl. These phenotypic characteristics are shared by C. concisus and C. mucosalis (7). C. mucosalis can be differentiated from C. concisus by its ability to grow at 25°C, its cephalothin sensitivity, and its dirty yellow colony color (6). The issue of growth of C. mucosalis at 25°C is controversial (6, 7). Almost all the clinical isolates, plus isolate NCTC 12408, did not grow at 25°C. Fifteen clinical isolates that were cephalothin sensitive (inhibitory zone sizes of up to 40 mm) and that had a dirty yellow colony color were selected. In other words, as defined by phenotypic criteria, these isolates were C. mucosalis. All 15 clinical isolates plus isolate NCTC 12408 were positive for both arylsulfatase and pyrazinamidase, which is characteristic of C. concisus and not C. mucosalis (1). High-stringency DNA-DNA hybridization studies were performed with theseprobes: C. mucosalis NCTC 1 1000T C. concisus NCTC 11485, C. curvus NCTC 11649T, and C. rectus NCTC 11489T. Isolate NCTC 12408 and all 15 clinical isolates reacted strongly with the C. concisus probe and did not react with any other probe. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2) confirmed that the 16 isolates were C. concisus. The phenotypic description of C. mucosalis isolates was based on only a few isolates (6). Isolate NCTC 12408 was characterized at NCTC by phenotypic, not molecular, methods as "C. mucosalis-like" (5a). As more and more clinical laboratories adopt filtration and H2-enhanced microaerophilic growth conditions, the problems of differentiating C. mucosalis and C. concisus and related species are becoming apparent. Molecular methods must be used for the precise identification of these underdetected pathogens.

Intracranial Fusariosis: A Novel Cause of Fungal Meningoencephalitis in a Dog

“…31 False negatives may also occur. 19,36,41 The serologic tests used in this case, however, screened for antibodies against A. fumigatus , A. terreus , A. niger , and A. flavus . Urinalysis and urine fungal cultures are often effective methods for diagnosing disseminated aspergillosis, 7 but in this case they were negative, further strengthening the case against aspergillosis.…”