Histoplasmosis infection in patients with rheumatoid arthritis, 1998-2009

Background

Patients with rheumatic diseases including rheumatoid arthritis (RA) are at increased risk for infections related to both the disease and its treatments. These include uncommonly reported infections due to histoplasmosis.

Methods

Medical record review of all patients with a diagnosis of RA who developed new histoplasmosis infection in an endemic region between Jan 1, 1998 and Jan 30, 2009 and who were seen at Mayo Clinic in Rochester, Minnesota was performed.

Results

Histoplasmosis was diagnosed in 26 patients. Most patients were on combination therapies; 15 were on anti-tumor necrosis factor (anti-TNF) agents, 15 on corticosteroids and 16 on methotrexate. Most received more than 6 months of itraconazole and/or amphotericin treatment. Two patients died of causes unrelated to histoplasmosis. Anti-TNF treatment was restarted in 4/15 patients, with recurrence of histoplasmosis in one.

Conclusions

In this largest single center series of patients with RA and histoplasmosis in the era of immunomodulatory therapy, we found that most patients had longstanding disease and were on multiple immunomodulatory agents. Most cases were pulmonary; typical signs and symptoms of disease were frequently lacking.

Corrected version specificity of the latex test for cryptococcal antigen: a rapid, simple method for eliminating interference factors

An enzymatic method involving a protease (pronase) for the elimination of interference factors in the latex test for cryptococcal antigen was developed and compared with dithiothreitol treatment. The two were equivalent in their ability to remove interference factors; however, the enzymatic method generally yielded higher titers. The method is simple, requires only 20 min, and makes the latex test for cryptococcal antigen specific.

Pseudomycetoma caused by Microsporum canis in an immunosuppressed patient: a case report and review of the literature

BACKGROUND

A 65-year-old woman with a history of liver and kidney transplantation presented with a pruritic and tender rash of 2-year duration on her left knee.

METHODS

The patient had a physical examination, and multiple skin biopsies were performed.

RESULTS

Examination showed a cluster of dome-shaped, violaceous papules. A skin biopsy specimen showed multiple granules containing basophilic material within the superficial to mid dermis. The grains were embedded in an eosinophilic substance and surrounded by granulomatous inflammation. A Gomori methenamine silver stain showed abundant septate hyphae, and cultures grew colonies of Microsporum canis. A diagnosis of dermatophytic granuloma, or pseudomycetoma, was made. After considering the patient's immune status, a prolonged course of fluconazole was initiated.

CONCLUSION

Microsporum canis, a frequently encountered zoophilic dermatophyte associated with tinea capitis and tinea corporis, is rarely associated with a mycetoma-like presentation, grain formation, or systemic infection. The medical literature describes only six cases of M. canis causing mycetoma-like formations in immunocompromised and immunocompetent patients. This case report describes an unusual presentation of a common dermatophyte infection, and the literature review summarizes the importance of recognizing atypical presentations of dermatophyte infections. Such infections may warrant more aggressive treatment in immunocompromised patients.

Systemic histoplasmosis: a 15-year retrospective institutional review of 111 patients

To our knowledge, an institutional review of systemic histoplasmosis has not been conducted in the United States since the major outbreaks in Indianapolis in 1978-4982. We conducted a retrospective review of all patients with systemic histoplasmosis diagnosed at Mayo Clinic over a 15-year period. The case definitions employed were based on an international consensus statement by the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group (EORTC/IFICG) and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (MSG). One hundred eleven patients with systemic histoplasmosis were identified between January 1, 1991, and December 31, 2005. Of these, 78 patients had disseminated histoplasmosis and 55 patients had Histoplasma capsulatum fungemia. The mean age of patients was 55 years, 66% were male, and 98% were white. Fifty-nine percent of patients were immunocompromised. Fever was the most frequently reported symptom (63%), followed by respiratory complaints (43%) and weight loss (37%). The peripheral white blood cell count was <3000 cells/mm in 28%, hemoglobin was <10 g/dL in 29%, and platelet count was <150,000 cells/mm in 41% of patients. Liver enzymes were elevated (alanine aminotransferase >60 U/L in 39%, aspartate aminotransferase >60 U/L in 27%), alkaline phosphatase was >200 U/L in 55%, and albumin was <3.5 g/dL in 70%. Serologic and histopathologic examinations were each positive in 75% of cases, Histoplasma urine antigen screening was positive in 80%, and H. capsulatum was culture positive in 84%. Forty-seven percent of patients were sequentially treated with an amphotericin B-containing product followed by itraconazole, 31% received itraconazole alone, and 7% received an amphotericin B-containing product only. Another 13% of patients did not receive antifungal treatment, and the remaining 2% did not have treatment data available. Sixty percent of patients required hospitalization, and in hospital mortality was 6% with a median survival time of 61 days. The relapse rate was 9%, with a median relapse-free survival of 857 days. Systemic histoplasmosis should be suspected in patients who have lived in endemic areas with fever, bone marrow suppression, and elevated hepatic enzymes, particularly if they are immunocompromised. Evaluation including a combination of Histoplasma serologic screening, urine antigen assay, and fungal culture will secure the diagnosis in most cases.

Rhino-orbitocerebral mucormycosis caused by Apophysomyces elegans

Rhino-orbitocerebral mucormycosis (ROCM) caused by more common zygomycetes (e.g., Mucor) is known to cause rapidly fatal infections in immunocompromised patients. Apophysomyces elegans is an emerging zygomycete that has been reported to cause invasive cutaneous and rhino-orbitocerebral infections in immunocompetent individuals. Limited data exist describing the syndrome of ROCM caused by A. elegans. We describe a recent case and performed a comprehensive literature review to delineate the clinical characteristics of ROCM caused by A. elegans. Our case is a 50-year-old man with diabetes mellitus who presented with facial pain and right eye proptosis. Endoscopic sinus sampling revealed A. elegans. He was treated with liposomal amphotericin B and multiple debridements, with no disease on 1.5-year follow-up examination. Seven cases were identified on literature review, including the present case. Most patients (86%) were male, with a mean age of 40 years. Most patients (71%) did not have predisposing medical conditions. Three patients had predisposing head trauma. All presented with facial and/or periorbital pain. All had magnetic resonance imaging or computed tomography of the head showing intraorbital and/or sinus inflammation. Diagnosis was confirmed by histopathology and deep tissue culture in all cases. All patients required eye exenteration and extensive surgical debridement, in addition to intravenous amphotericin B. Six of the seven patients (86%) recovered. ROCM caused by A. elegans is rarely reported in the literature. Most such infections occurred in immunocompetent patients, often after facial trauma. Survival in ROCM caused by A. elegans is favorable in reported cases, with prompt surgical debridement and antifungal therapy.

A real-time polymerase chain reaction assay for detection of Pneumocystis from bronchoalveolar lavage fluid

Pneumocystis jiroveci is an important cause of pneumonia in immunocompromised individuals. This organism cannot be cultured, and therefore, diagnosis relies on microscopic identification of the organism using stains or antibodies. Although simple, these tests are insensitive and require expertise for accurate interpretation. We developed a real-time polymerase chain reaction (PCR) assay that provides sensitive and objective detection of Pneumocystis from bronchoalveolar lavage fluid. Primers and fluorescence resonance energy transfer probes were developed that target the cdc2 gene of P. jiroveci. Assay sensitivity is 6 copies of target per microliter of sample. No cross-reactivity occurs with other pathogens, and the PCR assay has a 21% increase in clinical sensitivity as compared with Calcofluor white staining. The real-time PCR assay provides a sensitive, rapid, and objective method for the detection of Pneumocystis from bronchoalveolar lavage fluid.

Multicenter evaluation of a Candida albicans peptide nucleic acid fluorescent in situ hybridization probe for characterization of yeast isolates from blood cultures

We evaluated aliquots from 244 clinical blood culture bottles that demonstrated yeasts on Gram stain using a Candida albicans peptide nucleic acid (PNA) fluorescent in situ hybridization (FISH) probe. The sensitivity, specificity, positive predictive value, and negative predictive value of the C. albicans PNA FISH test in this study were 99%, 100%, 100%, and 99.3%, respectively.

Influence of starch intake on growth and skeletal development of weanling horses1,2

Forty-four weanling horses were used in two experiments to evaluate the effect of starch intake on growth and skeletal development. In Exp. 1, the weanlings were fed either a grain-based, high-starch (31.1%, DM basis) concentrate or a by-product-based, low-starch (0.0%) concentrate with coastal bermudagrass (Cynodon dactylon) hay. Corn oil was used to equalize the energy concentration of the concentrates. The concentrate:hay ratio was 64:36 (as-fed basis), and intake was the same for both diets. Body weight gains were greater by the weanlings consuming the high-starch concentrate (0.81 vs. 0.67 kg/d; P = 0.01). Total body length gain also was greater for the weanlings consuming the high-starch concentrate (15.5 vs. 13.2 cm; P = 0.045). Other body measurements and bone mineral deposition were not influenced by diet or gender. At the end of the experiment, postprandial blood glucose concentrations suggested that the horses on the low-starch diet were less efficient in metabolizing blood glucose than were those that had been consuming the high-starch diets. In Exp. 2, the weanlings were fed either a high-starch (34.7%) or medium-starch (17.0%) concentrate plus coastal bermudagrass hay. Corn oil again was used to equalize the energy content of the medium-starch concentrate to that of the high-starch concentrate. The concentrate:hay ratio was 64:36 (as-fed basis), and the intake was the same for both diets. The diets did not influence rate of gain (0.75 kg/d; P = 0.98), body measurements (P = 0.11 to 0.93), or bone mineral deposition (P = 0.66). Animals on the medium-starch diet tended to have blood glucose concentrations that peaked earlier and were lower at later times than those consuming the high-starch concentrate. Bone osteochondrotic lesions were not related to the diet and were found to decrease during the course of the experiment for both the high-starch and the medium-starch diets (P = 0.006 and 0.016, respectively).

Mycobacterium parmense sp. nov

The isolation and identification of a novel, slow-growing, scotochromogenic, mycobacterial species is reported. A strain, designated MUP 1182T, was isolated from a cervical lymph node of a 3-year-old child. MUP 1182T is alcohol- and acid-fast, with a lipid pattern that is consistent with those of species that belong to the genus Mycobacterium. It grows slowly at 25-37 degrees C, but does not grow at 42 degrees C. The isolate was revealed to be biochemically distinct from previously described mycobacterial species: it has urease and Tween hydrolysis activities and lacks nitrate reductase, 3-day arylsulfatase and beta-glucosidase activities. Comparative 16S rDNA sequencing showed that isolate MUP 1182T represents a novel, slow-growing species that is related closely to Mycobacterium lentiflavum and Mycobacterium simiae. On the basis of these findings, the name Mycobacterium parmense sp. nov. is proposed, with MUP 1182T (=CIP 107385T=DSM 44553T) as the type strain.

Clinical and laboratory features of Mycobacterium porcinum

Recent molecular studies have shown Mycobacterium porcinum, recovered from cases of lymphadenitis in swine, to have complete 16S rDNA sequence identity and >70% DNA-DNA homology with human isolates within the M. fortuitum third biovariant complex. We identified 67 clinical and two environmental isolates of the M. fortuitum third biovariant sorbitol-negative group, of which 48 (70%) had the same PCR restriction enzyme analysis (PRA) profile as the hsp65 gene of M. porcinum (ATCC 33776(T)) and were studied in more detail. Most U.S. patient isolates were from Texas (44%), Florida (19%), or other southern coastal states (15%). Clinical infections included wound infections (62%), central catheter infections and/or bacteremia (16%), and possible pneumonitis (18%). Sequencing of the 16S rRNA gene (1,463 bp) showed 100% identity with M. porcinum ATCC 33776(T). Sequencing of 441 bp of the hsp65 gene showed four sequevars that differed by 2 to 3 bp from the porcine strains. Clinical isolates were positive for arylsulfatase activity at 3 days, nitrate, iron uptake, D-mannitol, i-myo-inositol, and catalase at 68 degrees C. They were negative for L-rhamnose and D-glucitol (sorbitol). Clinical isolates were susceptible to ciprofloxacin, sulfamethoxazole, and linezolid and susceptible or intermediate to cefoxitin, clarithromycin, imipenem, and amikacin. M. porcinum ATCC 33776(T) gave similar results except for being nitrate negative. These studies showed almost complete phenotypic and molecular identity between clinical isolates of the M. fortuitum third biovariant D-sorbitol-negative group and porcine strains of M. porcinum and confirmed that they belong to the same species. Identification of M. porcinum presently requires hsp65 gene PRA or 16S rRNA or hsp65 gene sequencing.

Purification and characterization of Mycobacterium tuberculosis KatG, KatG(S315T), and Mycobacterium bovis KatG(R463L)

Isoniazid, a first-line antibiotic used for the treatment of tuberculosis, is a prodrug that requires activation by the Mycobacterium tuberculosis enzyme KatG. The KatG(S315T) mutation causes isoniazid resistance while the KatG(R463L) variation is thought to be a polymorphism. Much of the work to date focused on isoniazid activation by KatG has utilized recombinant enzyme overexpressed in Escherichia coli. In this work, native KatG and KatG(S315T) were purified from M. tuberculosis, and KatG(R463L) was purified from Mycobacterium bovis. The native molecular weight, enzymatic activity, optical, resonance Raman, and EPR spectra, K(D) for isoniazid binding, and isoniazid oxidation rates were measured and compared for each native enzyme. Further, the properties of the native enzymes were compared and contrasted with those reported for recombinant KatG, KatG(S315T), and KatG(R463L) in order to assess the ability of the recombinant enzymes to act as good models for the native enzymes.

Emerging fungal diseases: the importance of the host

More yeasts and molds are now recognized to cause more human disease than ever before. This development is not due to a change in the virulence of these fungi, but rather to changes in the human host. These changes include immunosuppression secondary to the pandemic of HIV, the use of life-saving advances in chemotherapy and organ transplantation, and the use of corticosteroids and other immunosuppressive agents to treat a variety of diseases. Fungi that were once considered common saprophytes are now recognized as potential pathogens in these patients. This situation necessitates better communication than ever between the clinician, pathologist, and clinical mycologist to ensure the prompt and accurate determination of the cause of fungal diseases.

Mycobacterium celatum, an emerging pathogen and cause of false positive amplified mycobacterium tuberculosis direct test

Mycobacterium celatum is a recently described organism. Herein we describe a case of M. celatum lymphadenitis in an immunocompetent child and the first reported case of a M. celatum infection (lung abscess) in a transplant recipient. A literature review identified 19 other cases of M. celatum infection. Fifteen occurred in patients with the acquired immunodeficiency syndrome. Of these, nine were disseminated and six were localized (primarily to the lungs). The remaining 4 patients were immunocompetent and had localized infection (pneumonitis or lymphadenitis). Diagnosis of M. celatum infection can be challenging as M. celatum can cause false-positive results with the current version of the Amplified Mycobacterium tuberculosis Direct Test (Gen-Probe, San Diego, CA.). Definitive identification is available by DNA sequencing or high-performance liquid chromatography. M. celatum can cause infection in immunocompromised and immunocompetent hosts.

Experience with the MicroSeq D2 large-subunit ribosomal DNA sequencing kit for identification of filamentous fungi encountered in the clinical laboratory

Described herein is our experience with the MicroSeq D2 large-subunit rDNA sequencing kit for the identification of filamentous fungi encountered in the mycology laboratory at the Mayo Clinic. A total of 234 filamentous fungi recovered from clinical specimens were used in the evaluation. All were identified by using phenotypic characteristics as observed macroscopically and microscopically on any medium or a combination of media, which included Sabouraud's dextrose, inhibitory mold, cornmeal, Czapek-Dox, potato dextrose, and V8 juice agars; all isolates were sequenced using the MicroSeq D2 large-subunit rDNA sequencing kit. Of the of 234 isolates, 158 were correctly identified to the appropriate genus or genus and species by using nucleic acid sequencing. Sequences for 70 (29.9%) of the isolates (27 genera) were not included in the MicroSeq library. Of the 80 dematiaceous and 154 hyaline fungi sequenced, 65 and 51.2%, respectively, gave results concordant with those determined by phenotypic identification. Nucleic acid sequencing using the MicroSeq D2 large-subunit rDNA sequencing kit offers promise of being an accurate identification system; however, the associated library needs to include more of the clinically important genera and species.

Experience with the MicroSeq D2 large-subunit ribosomal DNA sequencing kit for identification of commonly encountered, clinically important yeast species

Experience with a MicroSeq D2 large-subunit (LSU) ribosomal DNA (rDNA) sequencing kit for identification of yeast species commonly encountered in the mycology laboratory at Mayo Clinic is described here. A total of 131 isolates of yeasts recovered from clinical specimens were included in the study. Phenotypic methods used for initial identification included germ tube formation, urease production, microscopic morphological features on cornmeal agar, and an API 20C AUX system; all isolates were sequenced using a MicroSeq D2 LSU rDNA sequencing kit. Nucleic acid sequencing identified 93.9% of the isolates to the correct genus and species. A total of 100 of the isolates (representing 19 species of Candida) were sequenced, and 98% gave results concordant with identifications made by the API 20C AUX system; distance scores ranged from 0 to 1.88%, with an average value of 0.23%. Candida dubliniensis was not included in the MicroSeq database and was identified as Candida albicans. A total of 32 isolates representing 9 other genera (including Cryptococcus, Filobasidium, Kloeckera, Malassezia, Pichia, Sporidiobolus, Rhodotorula, Zygosaccharomyces, and Trichosporon) were included, and 81.3% showed concordant results when phenotypic and sequencing results were compared. Most discrepancies were attributed to the lack of inclusion of the species in the MicroSeq or API 20C AUX database. The MicroSeq D2 LSU rDNA sequencing kit appears to be accurate and useful for the identification of yeasts that might be seen in a clinical laboratory.

Laryngeal sporotrichosis causing stridor in a young child

Fungal infections of the larynx are rare entities that must be considered in the differential diagnosis of the patient who presents with laryngeal symptoms. We present an unusual case of initially recurrent and then persistent stridor in a 19-month-old girl, unresponsive to 4 months of antibiotic and steroid therapy. Upon our laryngoscopic examination, the patient was noted to have an ulcerated, granulomatous process involving the larynx. She also had an erythematous papule on the left thigh. Fungal cultures of both sites grew Sporothrix schenckii. The patient was treated with systemic antifungal medications and had complete resolution of her symptoms. We discuss the pathophysiology and possible source of this unusual form of sporotrichosis, the first such case reported in a child. We emphasize the role of empiric steroid therapy in exacerbating and eventually enabling dissemination of the infection. We also review the manifestations of sporotrichosis infections of the head and neck. This case demonstrates the vital importance of careful diagnosis and proper treatment of stridor in children.

Evaluation of the MicroSeq system for identification of mycobacteria by 16S ribosomal DNA sequencing and its integration into a routine clinical mycobacteriology laboratory

An evaluation of the MicroSeq 500 microbial identification system by nucleic acid sequencing and the Mayo Clinic experience with its integration into a routine clinical laboratory setting are described. Evaluation of the MicroSeq 500 microbial identification system was accomplished with 59 American Type Culture Collection (ATCC) strains and 328 clinical isolates of mycobacteria identified by conventional and 16S ribosomal DNA sequencing by using the MicroSeq 500 microbial identification system. Nucleic acid sequencing identified 58 of 59 (98.3%) ATCC strains to the species level or to the correct group or complex level. The identification results for 219 of 243 clinical isolates (90.1%) with a distance score of <1% were concordant with the identifications made by phenotypic methods. The remaining 85 isolates had distance scores of >1%; 35 (41.1%) were identified to the appropriate species level or group or complex level; 13 (15.3%) were identified to the species level. All 85 isolates were determined to be mycobacterial species, either novel species or species that exhibited significant genotypic divergence from an organism in the database with the closest match. Integration of nucleic acid sequencing into the routine mycobacteriology laboratory and use of the MicroSeq 500 microbial identification system and Mayo Clinic databases containing additional genotypes of common species and added species significantly reduced the number of organisms that could not be identified by phenotypic methods. The turnaround time was shortened to 24 h, and results were reported much earlier. A limited number of species could not be differentiated from one another by 16S ribosomal DNA sequencing; however, the method provides for the identification of unusual species and more accurate identifications and offers the promise of being the most accurate method available.

In situ hybridization for the differentiation of Aspergillus, Fusarium, and Pseudallescheria species in tissue section

Identification of fungi in tissue sections can be difficult. In particular, species of Aspergillus, Fusarium, and Pseudallescheria all appear as septate, branched hyphae. However, their differentiation can have significant clinical implications, as the latter two groups are often resistant to commonly used antifungal agents. In situ hybridization may assist in rapidly distinguishing these organisms in the absence of available culture. Oligonucleotide DNA probes were directed against the 5S, 18S, or 28S rRNA sequences of three groups of fungi with a high degree of specificity for each. Probes were tested on 26 formalin-fixed, paraffin-embedded tissue specimens, each with culture-proven involvement by one of these organisms: Fusarium species, n = 12; Pseudallescheria boydii, n = 5; Aspergillus species, n = 9 ( probe set validated in an earlier study). Accuracy of both ISH and morphology was compared with culture. Morphologic examination (GMS and PAS) showed a greater sensitivity in detecting fungi (100%) as compared with in situ hybridization (84.6%). When detected, however, DNA probes allowed definitive identification of organisms. While there was no ability to distinguish between the three groups of organisms by morphologic features, ISH probes showed 100% positive predictive value (PPV, 19/19 organisms identified correctly). No cross-reactivity was observed when the probes were tested against other genera (100% specificity). Furthermore, the use of ISH allowed the detection of mixed fungal infections involving multiple organism types in two cases, demonstrating another advantage over morphology. In situ hybridization, directed against rRNA sequences, provides a rapid and accurate technique for distinguishing commonly encountered, nonpigmented filamentous fungi in histologic sections. While less sensitive than morphology, ISH is highly accurate and may help to distinguish between organisms that have similar or identical morphologic features by light microscopy.

Oxidative stress increases susceptibility of Mycobacterium tuberculosis to isoniazid

Isoniazid is a first-line antibiotic used in the treatment of infections caused by Mycobacterium tuberculosis. Isoniazid is a prodrug requiring oxidative activation by the catalase-peroxidase hemoprotein, KatG. Resistance to isoniazid can be obtained by point mutations in the katG gene, with one of the most common being a threonine-for-serine substitution at position 315 (S315T). The S315T mutation is found in more than 50% of isoniazid-resistant clinical isolates and results in an approximately 200-fold increase in the MIC of isoniazid compared to that for M. tuberculosis H37Rv. In the present study we investigated the hypothesis that superoxide plays a role in KatG-mediated isoniazid activation. Plumbagin and clofazimine, compounds capable of generating superoxide anion, resulted in a lower MIC of isoniazid for M. tuberculosis H37Rv and a strain carrying the S315T mutation. These agents did not cause as great of an increase in isoniazid susceptibility in the mutant strain when the susceptibilities were assessed by using the inhibitory concentration that causes a 50% decrease in growth. These results provide evidence that superoxide can play a role in isoniazid activation. Since clofazimine alone has antitubercular activity, the observation of synergism between clofazimine and isoniazid raises the interesting possibility of using both drugs in combination to treat M. tuberculosis infections.

In situ hybridization for the identification of filamentous fungi in tissue section

Identification of fungi in tissue sections can be difficult because of limited biopsy tissue with only a few organisms present, or mycelial elements may be the only forms present, rendering common organism types indistinguishable from one another. In situ hybridization may assist in the rapid and accurate identification of such fungi. In this study, DNA probes were directed against the 5S or 18S ribosomal RNA sequences of three groups of fungi with a high degree of specificity for each. Two of the three, Aspergillus and Zygomycetes species, are usually seen in tissue purely in their hyphal forms. The third, Candida species is seen less commonly as predominantly mycelial elements. Probes were tested on 61 formalin-fixed, paraffin-embedded tissue specimens, each with culture-proven involvement by one of these organisms (Candida species, n = 21; Aspergillus species, n = 27; Zygomycetes, n = 13). Accuracy of both in situ hybridization (ISH) and morphology, based on the examination of Grocott methanamine silver (GMS)- and periodic acid-Schiff (PAS)-stained slides, was compared with culture. The results showed that morphologic examination (GMS and PAS) showed a slightly greater sensitivity in detecting the presence of fungi (98%) compared with in situ hybridization (95%). DNA probes, however, were more accurate in correctly identifying those organisms present. Although ISH specific probes showed 97% positive predictive value (PPV), examination of GMS-and PAS-stained slides had an 86% PPV when compared with culture-based identification methods. These results show that ISH, directed against ribosomal RNA, provides a rapid and accurate technique for the identification of mycelial fungal organisms in histologic tissue sections. Its primary use lies in the ability to accurately distinguish between organisms that have similar or identical morphologic features by light microscopy.

Evaluation of Gen-Probe amplified mycobacterium tuberculosis direct test by using respiratory and nonrespiratory specimens in a tertiary care center laboratory

The performance of the Amplified Mycobacterium Tuberculosis Direct (AMTD) test (Gen-Probe Inc., San Diego, Calif.) was assessed in a large tertiary care mycobacteriology laboratory. Both acid-fast smear-positive and smear-negative respiratory and nonrespiratory clinical specimens were analyzed. From February 1998 to 4 October 2001, AMTD assays were performed on 391 respiratory specimens and 164 nonrespiratory specimens. The AMTD assay was compared to the "gold standard" of combined culture and clinical diagnosis. The overall sensitivity for all specimens, including those for which no smear result was available, was 91.2%. The overall sensitivities of the assay, including acid-fast smear-positive and -negative specimens, were 97.8 and 77.3% for respiratory and nonrespiratory specimens, respectively. The corresponding specificities for respiratory and nonrespiratory specimens were 99.1 and 98.5%, respectively. The overall specificity for all specimens was 98.9%. Positive and negative predictive values were 93.9 and 99.7% and 91.7 and 96.4% for respiratory and nonrespiratory specimens, respectively. The time saved by using the AMTD test for making a diagnosis of tuberculosis instead of using culture was 8.99 days. Inhibitors to the AMTD assay were found in 3.1% of respiratory specimens and 3.1% of nonrespiratory specimens. The assay, used in a general mycobacteriology laboratory setting, represents an important advance in improving the speed and accuracy of diagnosis in the management of patients with tuberculosis.

Sporotrichosis masquerading as pyoderma gangrenosum: case report and review of 19 cases of sporotrichosis

We present the case of a 59-year-old woman who had large ulcerations on her right leg that were diagnosed initially as pyoderma gangrenosum and treated with three immunosuppressive agents (cyclosporin, prednisone and azathioprine) for 6 months. Results of a biopsy at 6 months showed numerous cigar-shaped bodies consistent with Sporothrix schenckii; identification was confirmed by tissue culture. A retrospective review was performed for all cases diagnosed as sporotrichosis from tissue culture or biopsy specimens at the Mayo Clinic. Nineteen cases were identified. The present case was the only one in which fungal organisms were visible on histological examination. The present case emphasizes the importance of making a definitive histological diagnosis in unusual ulcer cases or in suspected cases of pyoderma gangrenosum before the initiation of immunosuppressive therapy. The large number of cigar-shaped bodies in the tissue is a rare finding in sporothrix infection and has been reported in only two cases previously.

Quantitative analysis of chondroitin sulfate isomers in intervertebral disk chondrocyte culture using capillary electrophoresis

Chondroitin sulfate (CS) isomers, 6-sulfate (CS6) and 4-sulfate (CS4), change their ratio to each other in cartilaginous tissues with aging. In this study, a quantitative measurement method of CS6 and CS4 was developed, using capillary electrophoresis (CE). Various buffer solutions, pH, and digestion times were studied, and the use of 0.1 M Tris-HCl at pH of 8.0 allowed the isolation of CS6 and CS4 from CS most efficiently when combined with chondrotinase ABC at a concentration of 1 mU/microg of the substrate during a 3 hr digestion period. Amounts of newly synthesized CS6 and CS4 in the intervertebral disk chondrocyte three-dimensional culture were quantified by this method after the proteoglycans were extracted by equilibrium density centrifugation.

Functional interaction between fluorodeoxyuridine-induced cellular alterations and replication of a ribonucleotide reductase-negative herpes simplex virus

G207 is an oncolytic herpes simplex virus (HSV) which is attenuated by inactivation of viral ribonucleotide reductase (RR) and deletion of both gamma(1)34.5 genes. The cellular counterparts that can functionally substitute for viral RR and the carboxyl-terminal domain of ICP34.5 are cellular RR and the corresponding homologous domain of the growth arrest and DNA damage protein 34 (GADD34), respectively. Because the thymidylate synthetase (TS) inhibitor fluorodeoxyuridine (FUdR) can alter expression of cellular RR and GADD34, we examined the effect of FUdR on G207 bioactivity with the hypothesis that FUdR-induced cellular changes will alter viral proliferation and cytotoxicity. Replication of wild-type HSV-1 was impaired in the presence of 10 nM FUdR, whereas G207 demonstrated increased replication under the same conditions. Combined use of FUdR and G207 resulted in synergistic cytotoxicity. FUdR exposure caused elevation of RR activity at 10 and 100 nM, whereas GADD34 was induced only at 100 nM. The effect of enhanced viral replication by FUdR was suppressed by hydroxyurea, a known inhibitor of RR. These results demonstrate that the growth advantage of G207 in FUdR-treated cells is primarily based on an RR-dependent mechanism. Although our findings show that TS inhibition impairs viral replication, the FUdR-induced RR elevation may overcome this disadvantage, resulting in enhanced replication of G207. These data provide the cellular basis for the combined use of RR-negative HSV mutants and TS inhibitors in the treatment of cancer.

Computed radiography

CR is a useful tool for the equine veterinarian and has many advantages. Its only major disadvantage is the initial cost, in dollars and time, for setup in one's practice. CR is already in use at several universities and private practices in the United States and around the world. In the future, as is the case with any computer-based technology, this modality should become more affordable and readily available to smaller practices. The potential of CR in veterinary medicine combined with saturation of the human market is driving the development of specialized software and algorithms for veterinary medicine.

In situ hybridization for the identification of yeastlike organisms in tissue section

The identification of yeast and yeastlike organisms in tissue sections can be very difficult. Biopsy tissues may be limited, with only occasional organisms present. In addition, several common species have overlapping histologic features. Deoxyribonucleic acid probes were designed to detect both the 18S and 28S ribosomal ribonucleic acid sequences of five fungal organisms with a high degree of specificity for each fungus. Each of these organisms--Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum, and Sporothrix schenckii--can be manifested histologically as round, yeastlike structures, often within a similar size range. Probes were tested against 98 archived, formalin-fixed, paraffin-embedded tissue specimens, each of which had culture-proved involvement by one of these organisms. Assessment of accuracy was based on the presence of yeastlike organisms in consecutive Grocott's methanemine silver (GMS)-stained tissue sections, and agreement with culture results. The results indicated that GMS had a greater overall sensitivity in detecting fungal organisms (95.9%) compared with in situ hybridization (ISH; 82.7%). ISH with oligonucleotide deoxyribonucleic acid probes, however, was more specific, with all species-specific probes yielding 100% specificity (compared with 96.2-100% specificity based on morphology alone). ISH also had a higher positive predictive value (100% in all cases) compared with GMS (83.3-100%). In addition, four cases with rare organisms present (4.1% of cases tested) were detected by ISH but not by GMS staining. These results show that ISH, directed against ribosomal ribonucleic acid, provides a rapid, accurate technique for the identification of yeastlike organisms in histologic tissue sections. Its primary strength lies in the ability to speciate organisms accurately that are too few or atypical to identify based solely on morphologic features.

Ramichloridium mackenziei brain abscess: report of two cases and review of the literature

We report two cases of brain abscesses caused by Ramichloridium mackenziei, a neurotropic dematiaceous fungus that seems to be geographically restricted to the Middle East. One of the patients had chronic myelomonocytic leukemia but did not receive any chemotherapeutic agents. The other patient was a normal host. Both cases had a fatal outcome despite aggressive antifungal therapy and surgical intervention. Herein, we review all previously described cases in the literature, and discuss the epidemiology, mycology and histopathology of this life-threatening organism.

Quantitative hepatobiliary scintigraphy in normal cats and in cats with experimental cholangiohepatitis

Quantitative hepatobiliary scintigraphy using 99mTc-mebrofenin was performed on eight normal cats and on the same cats after induction of experimental cholangiohepatitis by infection with the liver fluke Platynosomum concinnum. Hepatobiliary scintigraphy was performed 3 times at 10 weeks, 4 months and 6 months after infection. In addition, routine biochemical tests, hepatic ultrasound and ultrasound guided hepatic biopsy samples were obtained at the same time points, and the results compared with hepatobiliary scintigraphy. The normal hepatic extraction fraction was determined to be 85%, and the normal hepatic excretion half time (T 1/2) was 14 minutes. There was no significant change in scintigraphic parameters compared to pre-infection values at any time following infection with the liver fluke. No correlation between scintigraphic parameters and histologic scores was found; however, significant correlation was identified between parasite burden and histologic scores 6 months following infection. Despite the presence of severe multifocal histologic abnormalities, minimal clinical, biochemical and scintigraphic derangements were identified using this model of cholangiohepatitis. Based on this study, hepatobiliary scintigraphy appears to be an insensitive test for structural hepatobiliary abnormalities. The role of hepatobiliary scintigraphy in functional hepatobiliary abnormalities of the feline liver has not been determined.

Performance of five agar media for recovery of fungi from isolator blood cultures

We studied the recovery of 1,270 fungal isolates from 176,144 Isolator blood cultures (0.72% positive) on bacterial and fungal media, under routine and differing incubation conditions. Except with Histoplasma capsulatum, chocolate agar incubated for only 3 days proved to be an excellent medium for the recovery of fungi from the Isolator system.

Esophageal transit of capsules in clinically normal cats

OBJECTIVE

To evaluate the esophageal passage of capsules in clinically normal cats and determine the incidence of prolonged transit or entrapment.

ANIMALS

12 clinically normal adult cats.

PROCEDURE

Esophageal transit of barium sulfate-filled capsules was evaluated fluoroscopically. Each cat was examined 3 times (36 examinations). Esophageal transit times were classified as normal (< or = 30 seconds) or prolonged (> 30 but < or = 240 seconds). Capsules were considered entrapped when transit times were > 240 seconds.

RESULTS

Transit times were normal in 10 of the 36 (27.8%) examinations, whereas times were prolonged in 7 (19.4%) examinations. Capsules became entrapped in the midcervical region of the esophagus during 19 (52.8%) examinations. Following termination of each examination, cats with entrapped capsules were fed a small amount (0.5 to 1 ounce) of food; this resulted in passage of the capsule to the stomach.

CONCLUSIONS AND CLINICAL RELEVANCE

The possibility of medication-induced esophagitis should be considered when orally administering ulcerogenic drugs to cats. It is recommended that a small volume of food be given following medications to ensure complete esophageal clearance.

Ultrasonographic features of canine gastrointestinal pythiosis

Pythiosis is a chronic pyogranulomatous infection of the gastrointestinal tract or skin caused by the water borne pathogen Pythium insidiosum. The ultrasonographic features of nine dogs with gastrointestinal pythiosis are reported. The stomach, duodenum, jejunum or colon were affected. All dogs had thickening of the gastrointestinal wall and areas with obliteration of the normal layered appearance. In one dog an eccentric mass was found arising from the serosal surface of the wall of the colon with mild diffuse wall thickening. Regional lymph node enlargement was seen in seven of the nine dogs. One dog had invasion of the pancreas and signs compatible with extrahepatic biliary obstruction. When compared to previous reports of gastrointestinal neoplasia, the features of wall thickening, loss of layering and regional lymphadenopathy are not considered specific for gastrointestinal pythiosis. Histological examination of tissue specimens is required for diagnosis.

Radiographic and ultrasonographic evaluation of the normal feline postpartum uterus

The radiographic and ultrasonographic appearance of the normal involution process of the feline postpartum uterus has not been previously described. Six queens were examined to determine the normal radiographic and ultrasonographic appearance of the involuting postpartum uterus. Radiographic and ultrasonographic examinations were performed daily from days one through ten, then on days 12, 14, 18, 24, and 28 postpartum. Radiographically the mean total uterine thickness was 16.5 mm at day one postpartum. By day 14 the mean total uterine thickness was 10.5 mm and by day 24 postpartum the uterus was not radiographically visible. Ultrasonographically at day one postpartum the mean total uterine thickness was 16.6 mm and the mean uterine wall thickness was 2.7 mm. At day 14 postpartum the mean total uterine thickness was 6.2 mm and the mean wall thickness was 2.1 mm. At day 28 postpartum the uterus could still be identified ultrasonographically however individual wall layers were not discernable.

Thoracic vertebral chordoma in a domestic ferret (Mustela putorius furo)

A castrated adult male 1.0-kg domestic ferret (Mustela putorius furo) was referred for evaluation of a mass of >5 mo duration that was associated with the thoracic spine. The ferret had motor dysfunction and no conscious proprioception or pain perception in either hind limb. Segmental reflexes were present. Survey radiography, myelography, and magnetic resonance imaging showed a mass involving the ninth and 10 thoracic vertebrae and compressing the spinal cord. Decompressive surgery was performed, but clinical signs persisted. A diagnosis of chordoma was made using histopathology and immunohistochemistry. This is the first reported case of a chordoma involving the thoracic vertebrae in a domestic ferret.

Quantitative magnetic resonance imaging of the normal feline cranial abdomen

Magnetic resonance images of the cranial abdomen were acquired from 15 clinically normal cats. All cats had T1-weighted images, 8 cats had T2-images made and 7 cats had T1-weighted post Gd-DTPA images acquired. Signal intensity measurements for T1, T2, and T1 post contrast sequences were calculated for liver, spleen, gallbladder, renal cortex, renal medulla, pancreas, epaxial muscles, and peritoneal fat. On T1-weighted images the epaxial muscle had the lowest signal intensity, followed by renal medulla, spleen, renal cortex, pancreas, liver and fat, respectively. On T2-weighted images, epaxial muscle had the lowest signal intensity followed by liver, spleen, fat, and gallbladder lumen. Calculations of specific organ percent enhancement following contrast medium administration were made and compared with that reported in humans. A brief review of the potential clinical uses of MR in cats is presented.

Dynamic magnetic resonance imaging of the normal canine pituitary gland

The pituitary glands of six normal dogs were evaluated using dynamic magnetic resonance imaging. T1 weighted images were obtained every 13 seconds for three minutes of three contiguous slices through the pituitary gland following a bolus intravenous injection of gadolinium-DTPA. Contrast enhancement was seen initially in the region of the pituitary stalk at 52-65 seconds followed by uniform enhancement at 104-143 seconds post injection. This pattern of enhancement was seen in all subjects and is similar to that reported in humans.

Assessment of barium impregnated polyethylene spheres (BIPS) as a measure of solid-phase gastric emptying in normal dogs--comparison to scintigraphy

Barium impregnated polyethylene spheres (BIPS) are radiopaque markers used for investigation of a variety of gastrointestinal disorders. One proposed use of the small (1.5 mm) marker is quantitative assessment of solid-phase gastric emptying, which may offer a simple, inexpensive alternative to nuclear medicine studies. In this study the rate and pattern of gastric emptying of a radiolabeled meal containing 30 small BIPS was evaluated in normal dogs by simultaneous comparison of the radiopaque marker method and a scintigraphic method. Serial scintigraphic images and radiographs were obtained for 8 hours or until 95% of the markers had left the stomach. Emptying curves were constructed and statistical analyses performed. There were significant differences in gastric emptying times and lag phase characteristics between the BIPS and scintigraphic studies. These results indicate that in normal dogs there are differences in both the rate and the pattern of solid-phase gastric emptying of a radiolabeled meal as assessed by scintigraphy and the gastric emptying of small BIPS.

The diagnosis and incidence of allergic fungal sinusitis

OBJECTIVE

To reevaluate the current criteria for diagnosing allergic fungal sinusitis (AFS) and determine the incidence of AFS in patients with chronic rhinosinusitis (CRS).

METHODS

This prospective study evaluated the incidence of AFS in 210 consecutive patients with CRS with or without polyposis, of whom 101 were treated surgically. Collecting and culturing fungi from nasal mucus require special handling, and novel methods are described. Surgical specimen handling emphasizes histologic examination to visualize fungi and eosinophils in the mucin. The value of allergy testing in the diagnosis of AFS is examined.

RESULTS

Fungal cultures of nasal secretions were positive in 202 (96%) of 210 consecutive CRS patients. Allergic mucin was found in 97 (96%) of 101 consecutive surgical cases of CRS. Allergic fungal sinusitis was diagnosed in 94 (93%) of 101 consecutive surgical cases with CRS, based on histopathologic findings and culture results. Immunoglobulin E-mediated hypersensitivity to fungal allergens was not evident in the majority of AFS patients.

CONCLUSION

The data presented indicate that the diagnostic criteria for AFS are present in the majority of patients with CRS with or without polyposis. Since the presence of eosinophils in the allergic mucin, and not a type I hypersensitivity, is likely the common denominator in the pathophysiology of AFS, we propose a change in terminology from AFS to eosinophilic fungal rhinosinusitis.

Recurrent cutaneous melanoma of the head and neck

INTRODUCTION

Recurrent cutaneous melanoma is generally regarded as having an extremely poor prognosis, particularly when regional lymph nodes are involved. A few reports have documented long-term survival among those patients treated for regionally recurrent melanoma.

METHODS

This article reviews patients at our institution undergoing complete neck dissection for recurrent head and neck melanoma.

RESULTS

Twenty-six patients with locoregionally recurrent cutaneous melanoma of the head and neck underwent complete neck dissection with or without parotidectomy. Seventeen of these procedures were for clinically evident cervical lymphadenopathy, whereas 9 of the neck dissections were done electively. Fourteen of the 17 patients with clinical adenopathy were confirmed to have cervical lymph node metastases. Two of the 9 patients who underwent elective neck dissections had pathologic lymph nodes. At 5 years, 38% of the patients with isolated neck recurrences not also having concurrent primary site recurrence were alive without disease.

CONCLUSIONS

These results provide further evidence suggesting a benefit in the form of long-term survival or cure for patients receiving aggressive surgical treatment for resectable recurrent head and neck melanoma involving cervical lymphatics in the absence of distant metastases.