False-positive galactomannan antigen testing in pulmonary nocardiosis.

Early diagnosis of invasive aspergillosis (IA) is facilitated by detection of galactomannan (GM) in serum and bronchoalveolar lavage fluid (BALF) using an enzyme-linked immunosorbent assay (ELISA). Although accurate, false positive results have been reported with these tests in numerous contexts. We report for the first time the occurrence of false positive GM ELISA due to nocardiosis, initially in a clinical sample of BALF from a patient with pulmonary nocardiosis, and subsequently corroborated by in vitro reactivity of 26% of tested isolates. Since patients at risk for IA are also at risk for nocardiosis, this finding has important clinical implications. LAY SUMMARY: Early diagnosis of aspergillosis has been facilitated by the routine use of antibody-based detection of galactomannan in various bodily fluids. We report for the first time the occurrence of false positive results of this assay in the context of nocardiosis.

Nocardiosis in patients with nephrotic syndrome: a retrospective analysis of 11 cases and a literature review.

OBJECTIVES: We evaluated the clinical manifestations and outcomes of nocardiosis, a rare opportunistic infection that occurs in patients with nephrotic syndrome. METHODS: The records of NS patients with nocardiosis in a single hospital during 2000-2019 were retrieved and studied in detail. RESULTS: Eleven patients were included. The mean time to develop nocardiosis after glucocorticoid therapy was 11.5 ± 14.8 months. Most patients had fever, elevated white blood cell counts and C-reactive protein, whereas procalcitonin levels were normal or slightly elevated in 91% (10/11) patients, except one patient suffered from septic shock. Nine patients were tested for CD4+ T-cell counts; of these, four patients had counts < 200 cells/µL. The most common site of nocardiosis involvement was lung (100%), followed by subcutaneous tissue (72.7%). Radiological findings for lungs in seven cases were characterized by isolated or scattered nodules and masses, usually located subpleural or close to the hilum. Positive smears of Nocardia were detected in 100% of samples of subcutaneous abscess and pleural fluid. Nine patients received oral trimethoprim-sulfamethoxazole, four of which received combined carbapenem, and the remaining two patients received carbapenem monotherapy. The long-term prognosis was excellent, with a treatment success rate of 100% in all patients. CONCLUSIONS: NS patients can develop immunodeficiency after treatment with glucocorticoid and immunosuppressants. In cases where patients develop systemic multiple abscesses, or lung images reveal isolated or scattered nodules and masses that are subpleural or close to the hilum, nocardial infection should be considered. Early diagnosis and specific treatment may improve patient outcomes.

Detection of high serum levels of ß-D-Glucan in disseminated nocardial infection: a case report.

BACKGROUND: ß-D-glucan (BDG) is a helpful diagnostic marker for many invasive fungal infections, but not for nocardiosis. Here, we reported the first case of nocardial infection with high serum level of BDG. CASE PRESENTATION: A 73-year-old man was hospitalized because of fever, headache, and appetite loss after 10 months of steroid and immunosuppressive therapy for cryptogenic organizing pneumonia. With a diagnosis of bacterial pneumonia, treatment with ampicillin/sulbactam was initiated. There was improvement on chest radiograph, but fever persisted. Further work-up revealed multiple brain abscesses on cranial magnetic resonance imaging (MRI). Serum galactomannan and BDG were elevated at 0.6 index and 94.7 pg/ml, respectively. Voriconazole was initiated for presumed aspergillus brain abscess. However, fever persisted and consciousness level deteriorated. Drainage of brain abscess was performed; based on the Gram stain and Kinyoun acid-fast stain, disseminated nocardiosis was diagnosed. Voriconazole was then shifter to trimethoprim/sulfamethoxazole. The presence of Nocardia farcinica was confirmed by the 16S rRNA gene sequence. Treatment course was continued; BDG level normalized after 1 month and cranial MRI showed almost complete improvement after 2 months. CONCLUSION: BDG assay is widely used to diagnose invasive fungal infection; therefore, clinicians should be aware that Nocardia species may show cross-reactivity with BDG assay on serum.

[Pulmonary nocardiosis with elevation of serum beta-D-glucan in a patient with polymyositis].

A 73-year-old woman with polymyositis, who had received corticosteroids and immune-suppressive agents, was admitted to our hospital because of general fatigue and severe cough. Chest X-ray film and CT scan showed a large tumor shadow in the left upper lobe and several ground-glass opacities (GGOs) scattered in both lungs. As the white blood cell and C-reactive protein levels were elevated, pnueumonia was suspected and antibiotics were administered. Subsequently, Nocardia spp. was cultured from the sputum and pulmonary nocardiosis was established. She gradually recovered after sulfamethoxazole-trimethoprim (ST) administration. The pretreatment serum beta-D-glucan level was highly elevated and decreased in parallel with clinical feature. In general, ST should be administered for 6 months to treat pulmonary nocardiosis in a compromised host. It is possible that P3-D-glucan may be a useful marker to treat pulmonary nocardiosis in patients with polymyositis.

Nocardia brasiliensis Modulates IFN-gamma, IL-10, and IL-12 cytokine production by macrophages from BALB/c Mice.

Interferon-gamma (IFN-gamma) is a critical cytokine involved in control of different infections. Actinomycetoma is a chronic infectious disease mainly caused by the bacterium Nocardia brasiliensis, which destroys subcutaneous tissue, including bone. Currently, the mechanism of pathogenesis in N. brasiliensis infection is not known. Here, we demonstrate that N. brasiliensis induced an IFN-gamma response in serum after 24 h of infection, while, in infected tissue, positive cells to IFN-gamma appeared in 2 early peaks: the first was present only 3 h after infection, then transiently decreased; and the second peak appeared 12 h after infection and was independent of interleukin-10. Resident macrophages produced an immediate IFN-gamma response 1 h after in vitro infection, and spleen-positive cells began later. The phase of growth of N. brasiliensis affected cytokine production, and exposure of macrophages to Nocardia opsonized with either polyclonal anti-Nocardia antibodies or anti-P61 monoclonal antibody led to a suppression of cytokine production. Our report provides evidence that N. brasiliensis as an intracellular bacterium modulates macrophage cytokine production, which helps survival of the pathogen. Modulation of these cytokines may contribute to pathogenesis once this bacterium is inside the macrophage.

Inmunoglobulinas en pacientes con actinomicetoma por Nocardia brasiliensis / Immunoglobulins in patients with Nocardia brasiliensis actinomycetoma

Considerando que algunos autores han reportado un aumento en la cantidad de algunas inmunoglobulinas en los pacientes con actinomicetoma, en este trabajo nos propusimos determinar diferencias en la producción de IgG1, IgG2, IgG3, IgG4 e IgM en 25 pacientes con actinomicetoma por Nocardia brasiliensis y 25 personas sanas provenientes de una zona endémica de micetoma. La determinación de inmunoglobulinas se realizó por medio de la técnica de ELISA. Para sensibilizar las placas se emplearon 6 antígenos de N. brasiliensis: un antígeno crudo denominado NB y cinco derivados del mismo (NB2, NB4, NB6, NB8 y NB10) separados por punto isoeléctrico. Los niveles de las cuatro subclases de IgG fueron mayores en los sueros de los pacientes que en el suero de los controles, con una diferencia máxima en IgG3 e IgG4; para esta última subclase, los seis antígenos fueron altamente reactivos. La concentración de IgM fue igual en ambos grupos. Es probable que como ocurre en otras infecciones, en la fisiopatogenia del actinomicetoma influya no sólo el aumento o deficiencia de una clase de inmunoglobulina, sino la relación que existe entre las diferentes subclases.

Considering that some authors have reported an increasing of some immunoglobulins in actinomycetoma patients, in this study we propose to determine differential production of IgG1, IgG2, IgG3, IgG4 and IgGM in 25 patients with actinomycetoma and 25 healthy individuals from a mycetoma endemic area. Immunoglobulins were determined by ELISA technique. To sensibilize the plates, six Nocardia brasiliensis antigens were used: a crude antigen denominated NB and five derivatives (NB2, NB4, NB6, NB8 and NB10) obtained by their isoelectric point. Results showed that all IgG subclasses were higher in the patients’ sera than in control sera, with a maximal difference to IgG3 and IgG4. To the latter subclass, six antigens were highly reactives. IgM levels were similar in both groups. As it occurs in other infections, in the actinomycetoma pathogenesis probably participate the increase or deficiency of a determined immunoglobulin class, as well as the relationship between different subclasses.

[Immunoglobulins in patients with Nocardia brasiliensis actinomycetoma]. / Inmunoglobulinas en pacientes con actinomicetoma por Nocardia brasiliensis.

Considering that some authors have reported an increasing of some immunoglobulins in actinomycetoma patients, in this study we propose to determine differential production of IgG1, IgG2, IgG3, IgG4 and IgGM in 25 patients with actinomycetoma and 25 healthy individuals from a mycetoma endemic area. Immunoglobulins were determined by ELISA technique. To sensibilize the plates, six Nocardia brasiliensis antigens were used: a crude antigen denominated NB and five derivatives (NB2, NB4, NB6, NB8 and NB10) obtained by their isoelectric point. Results showed that all IgG subclasses were higher in the patients' sera than in control sera, with a maximal difference to IgG3 and IgG4. To the latter subclass, six antigens were highly reactives. IgM levels were similar in both groups. As it occurs in other infections, in the actinomycetoma pathogenesis probably participate the increase or deficiency of a determined immunoglobulin class, as well as the relationship between different subclasses.

Diagnosis of nocardiosis by polymerase chain reaction: an experimental study in mice.

In this study, we have established a sensitive semi-nested polymerase chain reaction (PCR) for detection of Nocardia in clinical specimens by first amplifying a 422 bp DNA fragment from the groEL gene, followed by a second amplification of 342 bp DNA by targeting sequences internal to the first amplicon. The semi-nested PCR was evaluated in a murine model of nocardiosis for detection of Nocardia in blood and visceral organs. Healthy BALB/c mice were intravenously infected with 0.2 ml suspension of 2.9 x 10(5)/ml cfu of Nocardia asteroides and N. farcinica. Viable counts and seminested PCR were performed post-infection with samples of blood as well as lung, liver, spleen, kidney and brain at 5 minutes, 3 h, and then every 24 h for 3 days. Of the 20 blood samples tested, 15 (75%) were Nocardia positive by culture and 19 (95%) were positive by semi-nested PCR. Likewise, in case of N. asteroides infection, 46% organ samples were positive by culture and 58% by semi-nested PCR. The positivity of organ samples was higher with N. farcinica, 60% by culture and 72% by PCR, which may be attributed to its increased virulence as compared to N. asteroides. These results demonstrate that semi-nested PCR is a rapid and sensitive method for detection of Nocardia in blood and different visceral organs. The diagnostic application of this method provides an additional advantage over culture techniques, as PCR can also detect L-forms of Nocardia in clinical specimens, which otherwise fail to grow on routine isolation medium.

Pulmonary Nocardia otitidiscaviarum infection in a patient with chronic respiratory infection.

We report a case of pulmonary Nocardia (N.) otitidiscaviarum infection in a 76-year-old man with chronic respiratory infection. The patient responded poorly to intravenous imipenem and oral minocycline, but later improved after treatment with trimethoprim-sulfamethoxazole. Pulmonary infection with N. otitidiscaviarum should be considered in the differential diagnosis of chronic respiratory infections. Further studies are needed to evaluate the correlation between species and drug susceptibility.

Development of a serologic panel for the recognition of nocardial infections in a murine model.

A murine model was used to develop a sensitive and specific serologic test for clinical and subclinical infections caused by Nocardia. The following tests were used: (a) enzyme-linked immunosorbent assays (ELISAs) with culture filtrate and cytoplasmic extract antigens from Nocardia asteroides; (b) ELISA with N. asteroides trehalose dimycolate (cord factor); (c) indirect immunofluorescent antibody assay with whole cells of N. asteroides; and (d) Western-blot analysis for the 54 to 55-kD, 36-kD, and 62-kD proteins of N. asteroides. The sera from BALB/c mice, experimentally infected with nonlethal doses of three species of Nocardia, nine species of Mycobacterium, Rhodococcus equi, two species of Actinomadura, and two species of Streptomyces were tested using this panel. The serologic tests did, indeed, identify mice infected with nocardiae and could differentiate them from mice infected with the other actinomycetes, including mycobacteria.

[Pulmonary and cerebral nocardiosis in a patient infected with HIV]. / Nocardiose pulmonaire et cérébrale chez un patient infecté par le VIH.

We report a case of pulmonary and cerebral nocardiosis in a patient infected with HIV. On the basis of this observation, the authors review the frequency of nocardiosis during the course of an HIV infection and the diagnostic problems proposed, and finally the therapeutic difficulties encountered.

Disseminated Nocardia asteroides diagnosed by blood culture in a patient with disseminated histoplasmosis.

We describe herein a provocative case involving an immunosuppressed patient with disseminated Histoplasma capsulatum and also disseminated Nocardia asteroides, which was documented by multiple routine blood culture samples. Nocardia asteroides was isolated from 15 routine blood cultures using the nonradiometric blood culture system (Bactec NR-660, Becton Dickinson, Towson, Md). Several different species of the genus Nocardia proved to thrive in blood culture bottles (Bactec) when experimental inoculations were performed. The paucity of reports in the literature of disseminated nocardiosis with positive blood cultures has led us to consider cause for the apparent poor recovery of these organisms from blood culture media. We suggest that the media (Bactec) can successfully support growth of Nocardia species and that other variables, such as incubation times and subculture, should be considered to optimize isolation of this pathogen in blood culture systems.

Detection of metabolites by frequency-pulsed electron capture gas-liquid chromatography in serum and cerebrospinal fluid of a patient with Nocardia infection.

Serum (SR) and cerebrospinal fluid (CSF) from a patient suspected of having tuberculous meningitis were submitted to our laboratory for analysis by frequency-pulsed electron capture gas-liquid chromatography (FPEC GLC). The samples were tested for the presence of carboxylic acids, alcohols, hydroxy acids, and amines by methods described previously (C. C. Alley, J. B. Brooks, and D. S. Kellogg, Jr., J. Clin. Microbiol. 9:97-102, 1977; J. B. Brooks, C. C. Alley, and J. A. Liddle, Anal. Chem. 46:1930-1934, 1974; J. B. Brooks, D. S. Kellogg, Jr., M. E. Shepherd, and C. C. Alley, J. Clin. Microbiol. 11:45-51, 1980; J. B. Brooks, D. S. Kellogg, Jr., M. E. Shepherd, and C. C. Alley, J. Clin. Microbiol. 11:52-58, 1980). The results were different from previous FPEC GLC profiles of SR and CSF from patients with known tuberculous meningitis. Both the SR and CSF contained several unidentified compounds that were not previously detected in tuberculous meningitis or any of our other studies of body fluids. Nocardia brasiliensis was later isolated from the patient. Detection of these metabolites by FPEC GLC could prove to be useful for rapid diagnosis of Nocardia disease, and their identification will provide a better understanding of metabolites produced by Nocardia sp. in vivo.