Enzymatic characterization of Nocardia spp. and related bacteria by API ZYM profile

Characterization of 62 isolates belonging to the genus Nocardia and related bacteria was obtained by using the API ZYM system. The difference in enzymatic profile should allow a relatively efficient, low-cost means to identify aerobic actinomycetes of clinical significance.

Actinomycosis and other bronchopulmonary infections with bacterial granules

Pulmonary infections with formation of bacterial granules are rare. We reviewed the clinical and pathologic data from 18 cases diagnosed using surgical specimens in our department during the last 10 years. Three clinicopathologic forms were observed: endobronchial infections complicating tuberculous sequelae or bronchiectases (n = 7), tumor-like lesions (n = 8), and diffuse pneumonia (n = 3). The two latter forms contrasted with the former by a male predominance, association with general debilitating conditions and inflammatory syndrome, and pathologically by smaller granules often located in parenchymal abscesses or excavations. The pathologic examination of the bacteria forming the granules permitted the diagnoses of actinomycosis (n = 10), botryomycosis (n = 7), or nocardiosis (n = 1). The latter case corresponded to an endobronchial infection. Both actinomycosis and botryomycosis were encountered in every clinicopathologic form. At present, pulmonary actinomycosis and related infections rarely seems to present with chest wall invasion. On the contrary, purely endobronchial forms represented a large proportion of our cases. Cultures are often difficult and the clinical appearance is not specific. However, pathologic examination with special stains must indicate the type of involved microorganism.

Infections caused by Rhodochrous

Organisms conforming to "rhodochrous taxon" were isolated from three immunocompromised patients, suggesting a pathogenic role for the organisms. The organisms are partially acid-fast, gram-positive catalase positive rods which form orange or red colonies aerobically in three or four days on Sabouraud, Mueller-Hinton and Middlebrook 7H-10 agars. They are differenitated from Nocardia by morphology and ability to degrade ethylene glycol in 7H-10 media. Two of these clinical isolates and a reference strain were injected intraperitoneally into guinea pigs, half of which received methylprednisolone intramuscularly beginning three days prior to inoculation. Steroid-treated animals exhibited clinical illness, diffuse peritonitis and recovery of inoculated organisms whereas one of three nonsteroid-treated animals exhibited a localized abscess without recovery of organisms. This study suggests that rhodochrous may be pathogenic under conditions of immune compromise.

Nocardia jiangxiensis sp. nov. and Nocardia miyunensis sp. nov., isolated from acidic soils

The taxonomic positions of two soil actinomycetes, strains 117T and 43401T, provisionally assigned to the genus Nocardia were determined in a polyphasic study. The organisms were found to have phenotypic properties typical of members of the genus Nocardia, and formed a distinct branch in the Nocardia 16S rRNA gene tree. It was evident from the phylogenetic data that the isolates were most closely, albeit loosely, associated with the type strains of Nocardia nova and Nocardia pseudobrasiliensis. However, all four of these organisms were readily distinguishable from one another using DNA–DNA relatedness and phenotypic data. It is evident from the genotypic and phenotypic data that the two isolates should be recognized as novel species of the genus Nocardia. It is proposed, therefore, that strains 117T (=CGMCC 4.1904T=JCM 12860T) and 43401T (=CGMCC 4.1905T=JCM 12861T) be classified in the genus Nocardia as the type strains of Nocardia miyunensis sp. nov. and Nocardia jiangxiensis sp. nov., respectively.

Novel method for rapid identification of Nocardia species by detection of preformed enzymes

The purpose of the present study was to devise a method for the identification of Nocardia species that is more technically simple, accurate, and rapid than current standard methods of identification. We focused on a commercial bacteria identification system that contained chromogenic test substrates. Two MicroScan products were selected for use in the study on the basis of their content of chromogenic and conventional substrates. They were the Rapid Anaerobe Identification and the HNID panels. A total of 85 strains of Nocardia representing five species were used in the study. All isolates were identified as Nocardia species by the use of standard methods. The beta-naphthylamide-labeled substrate L-pyrrolidonyl-beta-naphthylamide (PYR), the nitrophenyl-labeled substrate p-nitrophenyl-alpha-D-mannopyranoside (MNP), and indoxyl phosphate were found to be useful for identification purposes. N. farcinica and N. nova were the only species positive for PYR, whereas N. brasiliensis was the only species that hydrolyzed MNP. All strains of N. brasiliensis, N. otitidiscavarium, and N. farcinica were positive for indoxyl phosphate, whereas strains of N. nova and N. asteroides sensu stricto were always negative. Agreement between the standard and enzymatic identification methods was 100%. In summary, detection of preformed enzymes appears to be a simple and reproducible method for the identification of Nocardia spp.

Clinical and clinical laboratory aspects of nocardial infection

It is nearly 100 years since Noeard described bovine farcy, a granulomatous disease of cattle characterized by abscesses, sinus tracts and pulmonary disease (Nocard, 1888). This was the first disease due toNocardiaspecies described. Since that time our knowledge of the role of the nocardiae in human veterinary diseases, of the epidemiology of these diseases, and their diagnosis and treatment, has enlarged rapidly. This paper attempts to give an overview of our current understanding of these diseases.

Nocardia coubleae sp. nov., isolated from oil-contaminated Kuwaiti soil

Two bacterial isolates from Kuwaiti soil contaminated by crude oil were analysed by using a polyphasic taxonomic approach. The isolates, designated OFN N11 and OFN N12T, were shown to have molecular, chemical and morphological properties typical of members of the genus Nocardia. Based on a multigenic approach that included 16S rRNA, hsp65 and sod gene sequencing, these novel isolates formed a monophyletic clade within the genus Nocardia. The closest species was Nocardia ignorata (with 99.4 %, 99.5 %, 98.6 % gene sequence similarity to the 16S rRNA, hsp65 and sod genes, respectively). The novel isolates could be distinguished phenotypically from the type strains of recognized species of the genus Nocardia. The novel isolates were not related to the type strain of N. ignorata in DNA–DNA hybridization experiments (26 % relatedness). On the basis of these genotypic and phenotypic data, the two isolates appear to represent a novel species, for which the name Nocardia coubleae sp. nov. is proposed. The type strain is OFN N12T (=DSM 44960T=CIP 108996T).

Isolation and genetic characterization of Nocardia seriolae from snubnose pompano Trachinotus blochii in Vietnam

A total of 480 cage-cultured fish were collected from 4 coastal provinces in central Vietnam to investigate the causative agent of nocardiosis. Fish displayed unique characteristics such as paleness and lethargy and exhibited haemorrhages and ulcers on the skin. Prominent white nodules varying in size were observed in the spleen, kidney, and liver. Furthermore, histopathological sections showed typical granulomatous lesions in these organs. Using the Ziehl-Neelsen staining method, isolated bacteria exhibited acid-fast, bead-like filament morphology when cultured in brain-heart infusion medium or Ogawa medium. Phylogenetic analysis of 16S rDNA confirmed that the isolated bacterium was Nocardia seriolae. This study demonstrates for the first time an outbreak of N. seriolae in snubnose pompano in central Vietnam.

Severe keratitis due to Nocardia farcinica

Keratitis due to Nocardia farcinica occurred in a 49-year-old female after inappropriate cleaning of her semipermeable rigid contact lenses with basin-stored water during a holiday in France. N. farcinica was differentiated from Nocardia asteroides by its growth at 45 degrees C, acid production from rhamnose, its opacification of Middlebrook 7H10 agar, and its marked degree of resistance to all cephalosporins, aminoglycosides, tetracyclins, macrolides, and trimethoprim-sulfamethoxazole. To the best of our knowledge, this is the first reported case of human N. farcinica keratitis, confirming that this microorganism can be responsible for serious human disease.

Fatal pulmonary Nocardia farcinica infection

Nocardia farcinica infections are rare and potentially life threatening. Identification is based on growth at 45 degreesC, opacification of Middlebrook 7H10 agar, and resistance to antibiotics. We describe a case of fatal pulmonary N. farcinica infection in a patient with pneumoconiosis that was diagnosed by culture of sputum onto selective media.

Dual color fluorescence in situ hybridization (FISH) assays for detecting Mycobacterium tuberculosis and Mycobacterium avium complexes and related pathogens in cultures

Two rapid dual color fluorescence in situ hybridization (FISH) assays were evaluated for detecting M. tuberculosis and related pathogens in cultures. The MN Genus-MTBC FISH assay uses an orange fluorescent probe specific for the Mycobacterium tuberculosis complex (MTBC) and a green fluorescent probe specific for the Mycobacterium and Nocardia genera (MN Genus) to detect and distinguish MTBC from other Mycobacteria and Nocardia. A complementary MTBC-MAC FISH assay uses green and orange fluorescent probes specific for the MTBC and M. avium complex (MAC) respectively to identify and differentiate the two species complexes. The assays are performed on acid-fast staining bacteria from liquid or solid cultures in less than two hours. Forty-three of 44 reference mycobacterial isolates were correctly identified by the MN Genus-specific probe as Mycobacterium species, with six of these correctly identified as MTBC with the MTBC-specific probe and 14 correctly as MAC by the MAC-specific probe. Of the 25 reference isolates of clinically relevant pathogens of other genera tested, only four isolates representing two species of Corynebacterium gave a positive signal with the MN Genus probe. None of these 25 isolates were detected by the MTBC and MAC specific probes. A total of 248 cultures of clinical mycobacterial isolates originating in India, Peru and the USA were also tested by FISH assays. DNA sequence of a part of the 23S ribosomal RNA gene amplified by PCR was obtained from 243 of the 248 clinical isolates. All 243 were confirmed by DNA sequencing as Mycobacterium species, with 157 and 50 of these identified as belonging to the MTBC and the MAC, respectively. The accuracy of the MN Genus-, MTBC-and MAC -specific probes in identifying these 243 cultures in relation to their DNA sequence-based identification was 100%. All ten isolates of Nocardia, (three reference strains and seven clinical isolates) tested were detected by the MN Genus-specific probe but not the MTBC- or MAC-specific probes. The limit of detection for M. tuberculosis was determined to be 5.1x10⁴ cfu per ml and for M. avium 1.5x10⁴ cfu per ml in liquid cultures with the respective MTBC- and MAC-specific probes in both the MN Genus-MTBC and MTBC-MAC FISH assays. The only specialized equipment needed for the FISH assays is a standard light microscope fitted with a LED light source and appropriate filters. The two FISH assays meet an important diagnostic need in peripheral laboratories of resource-limited tuberculosis-endemic countries.

First Clinical Isolates of Nocardia carnea, Nocardia elegans, Nocardia paucivorans, Nocardia puris and Nocardia takedensis in Japan

Five aerobic actinomycete strains isolated from patients in Japan were assigned provisionally to the genus Nocardia based on morphological and physiological characteristics. The five strains, IFM 10481, IFM 0668, IFM 0901, IFM 0583 and IFM 0342, were not classified into any Nocardia species reported as infectious agents in Japan. Therefore, they were studied further to determine their specific taxonomic positions. Detailed chemotaxonomic and physiologic characterization and 16S rDNA sequence data of the five strains showed that they belonged to respective species of Nocardia carnea, N. elegans, N. paucivorans, N. puris and N. takedensis. This is the first isolation report of these five Nocardia species from patients in Japan.

Pulmonary nocardiosis after lung transplantation: CT findings in 7 patients and review of the literature

OBJECTIVE

The purpose of this study is to review reported radiographic clues to the diagnosis of pulmonary nocardiosis, as well as to describe and illustrate the high-resolution computed tomography findings of 7 patients with pulmonary nocardiosis after lung transplantation.

CONCLUSIONS

Computed tomography findings of pulmonary nocardiosis after lung transplantation consist predominantly of nodules and cavitary lesions without any significant zonal or anatomic distribution. The diagnosis of pulmonary nocardiosis requires a high index of suspicion, as presenting symptoms are nonspecific, initial visualization is often not possible with routine stains, and identification requires prolonged cultures.

Molecular diagnosis of Nocardia farcinica from a cerebral abscess

Histopathology and special stains of a brain biopsy specimen from a 42-year-old man revealed numerous gram-positive bacilli arranged in branching filaments, suggesting Nocardia infection. Antibiotic therapy with trimethoprim-sulfamethoxazole markedly decreased the abscess size, and the patient improved. DNA was analyzed from formalin-fixed sections of the cerebral abscess by a 16S ribosomal DNA polymerase chain reaction assay demonstrating the presence of either Nocardia farcinica or N otitidiscaviarum. A species-specific polymerase chain reaction assay confirmed N farcinica as the etiologic agent.

Oerskovia xanthineolytica: a new pathogen in bone marrow transplantation

A 53-year-old woman with non-Hodgkin lymphoma underwent an autologous bone marrow transplant (BMT). Incomplete reconstitution necessitated the use of a long-term central venous catheter. One year after BMT she presented with fever. Echocardiography revealed vegetations on the tricuspid valve. Gram-positive rods grown from blood cultures and catheter tip were identified as Oerskovia xanthineolytica. We report the first case of native valve endocarditis caused by this organism.

Chemical characterization of organisms isolated from leprosy patients

CHEMICAL ANALYSES OF THE CELL WALLS OF ORGANISMS ISOLATED IN VARIOUS PARTS OF THE WORLD FROM CASES OF LEPROMATOUS AND TUBERCULOID LEPROSY MAKE POSSIBLE THEIR ASSIGNMENT TO ONE OF THE THREE GENERA: Corynebacterium, Mycobacterium, or Propionibacterium. One, bacterium 22M, remains unassigned. The combined chemical and enzymatic properties attributed to leprosy bacilli freshly harvested from lepromata are found collectively, but not individually, in these three genera.

An improved screening technique for isolation of Nocardia species from sputum specimens

Three selective isolation media and the paraffin baiting technique were compared with conventional culture (Sabouraud dextrose agar without antibiotic supplement) for the ability to grow and detect nocardiae from simulated sputum specimens. Modified Thayer-Martin medium, incorporating vancomycin, colistin, nystatin and trimethoprim as selective agents, produced the highest recovery rate and with the greatest suppression of normal respiratory tract flora. A clinical evaluation using a screening programme devised for a busy diagnostic microbiology laboratory was performed on 1600 sputum specimens. Inoculating sputum on modified Thayer-Martin medium and extending the initial incubation period of 3 days at 35 degrees C under 10% carbon dioxide to a further 3 weeks at room temperature in a candle jar, led to the diagnoses, which otherwise would have been missed, of pulmonary nocardiosis in 3 patients and pulmonary infections due to Neisseria meningitidis, Pseudomonas cepacia, and Serratia marcescens in a further 22 patients.

Nocardial brain abscess: observation of treatment strategies and outcome in Switzerland from 1992 to 1999

BACKGROUND

Brain abscesses caused by Nocardia spp. are rare, but life-threatening infections that are notoriously difficult to diagnose and treat and which occur mainly in immunocompromised patients. Standard treatment guidelines are not available.

METHODS

A systematic search for nocardial brain abscesses from 1992 to 1999 was conducted in Switzerland for the comparison of clinical presentation, treatment strategies and outcome.

RESULTS

Seven cases were found, for which data of six were available. In 4/6 patients antimicrobial therapy led to a decrease in the size of abscesses. Four of six patients died. The cause of death was likely due to underlying co-morbidities, rather than the nocardial infection.

CONCLUSION

The finding that treatment was different in each case underscores the lack of therapeutic guidelines.

The characterization of oil-degrading microorganisms from lubricating oil contaminated (scale) soil

AIMS

To isolate and characterize oil-degrading microorganisms from contaminated (scale) soil.

METHODS AND RESULTS

Oil-degrading microorganisms were isolated from enrichment cultures of scale soil. Each isolate was identified using 16S rDNA gene and oil degradability was determined on both unused and used lubricating oil. The weight of the extracted remaining oil revealed that most isolates degraded unused lubricating oil more than used lubricating oil. Chemical composition of oil analysed by TLC-FID and GC-MS demonstrated that Nocardia simplex W9 degraded used oil the best, and resulted in a decrease in saturates, aromatics and resins to 52.46, 38.13 and 18.81%, respectively.

CONCLUSIONS

Nocardia simplex W9 is the best degrader, among all the isolates, on both used and unused lubricating oil.

SIGNIFICANCE AND IMPACT OF THE STUDY

The presence of Nocardia simplex W9 in scale soil enables iron to be recycled by biodegradation.

Disseminated Nocardia brasiliensis infection with septic arthritis

An unusual case of disseminated Nocardia brasiliensis infection is presented. The patient, who had been receiving chronic dexamethasone therapy for 4 years, had pneumonia and septic arthritis of the left knee due to N. brasiliensis. To our knowledge, this is the first report from the United States of a synovial joint infection with this organism. Disseminated disease due to N. brasiliensis is infrequently reported; it is most often seen in the immunocompromised patient and is often unresponsive to therapy.

Pneumonia caused by Nocardia nova and Aspergillus fumigatus after cardiac transplantation

Nocardia nova, a newly established species of the Nocardia asteroides complex, has recently been characterized as a human pathogen. This report of a case of pneumonia caused by Nocardia nova and Aspergillus fumigatus in a patient after cardiac transplantation is the first reported infection caused by Nocardia nova following its detailed description. Accurate identification and susceptibility testing of the Nocardia nova isolate allowed successful oral therapy with clarithromycin when therapy with sulfisoxazole was not tolerated.

In vitro spheroplast and L-form induction within the pathogenic nocardiae

Six strains of Nocardia asteroides, two strains of N. caviae, and two strains of N. braziliensis were grown in medium supplementted with glycine, lysozyme, D-cycloserine, glycine plus lysozyme, and glycine plus D-cycloserine. It was shown that three strains of N. asteroides, and two strains of N. caviae, readily formed spheroplasts and/or protoplasts when grown in the presence of glycine plus either lysozyme or D-cycloserine. This process was studied by both phase contrast microscopy and electron microscopy. The induced cultures were then plated on hypertonic medium for the isolation of L-forms. It was shown that the organisms differed greatly in their ability to produce spheroplasts and subsequently grew as L-forms or transitional-phase variants.

Misidentification of Mycobacterium peregrinum, the causal organism of a case of bacteremia and automatic implantable cardioverter defibrillator-associated infection, due to its unusual acid-fast staining characteristics

We report an unusual case of Mycobacterium peregrinum bacteremia and infection of an automatic implantable cardioverter defibrillator that was originally misidentified as a Nocardia sp. due, in part, to its partially acid-fast staining characteristic, morphology, and odor. The misdiagnosis had a direct effect on patient care, though the patient was subsequently successfully treated.