Pulmonary granuloma caused by Pseudomonas andersonii sp nov

Isolation and characterization of "Pseudomonas andersonii" from four cases of pulmonary granulomas and emended species description

"Pseudomonas andersonii" is a Gram-negative bacillus initially isolated from a granulomatous lung lesion. Novel species status has not been validated for this single strain. We report four additional cases of pulmonary granuloma involving P. andersonii and further characterize the organism. These patients had pulmonary nodules that were surgically resected and which grew P. andersonii on routine culture. Mycobacterium avium complex was concomitantly isolated in two cases, and fungal structures were identified histopathologically in two other cases. The five P. andersonii strains described to date were similar in growth characteristics, biochemical reactions, matrix-assisted laser desorption ionization-time of flight mass spectrometry protein profiles, and susceptibility to antimicrobial agents. Their 16S rRNA genes were 99.9 to 100% identical but less than 95.0% similar to those of all other known bacteria. The gyrA genes of these strains were 99.5 to 100% identical. These shared features illustrate P. andersonii as a unique and distinct bacterium and support the novel species status of the organism.

Disseminated subcutaneous nocardiosis caused by Nocardia farcinica diagnosed by FNA biopsy and 16S ribosomal gene sequencing

Nocardia is an infrequent but significant cause of infections in the immunocompromised host. Clinical syndromes are varied and ranges from pulmonary, disseminated, cutaneous, and CNS involvement. Here we describe a case of disseminated subcutaneous nodules in a patient with multiple myeloma caused by Nocardia farcinica. The diagnosis was made by FNA biopsy which revealed gram positive filamentous bacilli in background of acute inflammation on smears. This was confirmed by 16S ribosomal gene sequencing. Prompt identification of N. farcinica is important because of its intrinsic resistance to broad spectrum cephalosporins and high risk of dissemination.

Pathological diagnosis of granulomatous lung disease: a review

Granulomas in the lung are common diagnostic problems encountered by pathologists. They occur in a wide range of pulmonary conditions, ranging from common entities to uncommon ones and including both infections and non-infectious diseases. This review summarizes the main histological features that help distinguish various granulomatous lung diseases. It concentrates on the most important and common entities that may be encountered and emphasizes helpful features in the differential diagnosis.

First reported infections caused by three newly described genera in the family Xanthomonadaceae

Members of the family of Xanthomonadaceae are typically characterized as environmental organisms. With the exception of Stenotrophomonas maltophilia, these organisms are infrequently implicated as human pathogens. We describe three cases of central venous catheter-associated bloodstream infections caused by Dokdonella koreensis, Aquimonas voraii, and a Luteibacter sp., all newly named genera within the family Xanthomonadaceae. The three patients all had histories of underlying hematological disorders, presented with fever, and recovered fully following treatment. These isolates required 16S rRNA gene sequencing for identification and, unlike S. maltophilia, demonstrated susceptibility to most antibiotics tested. This report represents the first description of human infections caused by these organisms.

Fusobacterial brain abscess: a review of five cases and an analysis of possible pathogenesis

OBJECT

The cases of five patients with fusobacterial brain abscess are presented. The authors discuss their attempt to determine the pathogenesis.

METHODS

The clinical and microbiological features of five cases of fusobacterial brain abscess are reviewed. Isolates of 2031 Fusobacterium spp. and other anaerobes collected (1989-2002) at our institution were analyzed and compared for incidences and isolation sources. The findings were correlated with extensive literature on the subject. The five patients were men between 45 and 74 years of age. All experienced an insidious onset of the disease and probable hematogenous seeding of the organism(s). One patient had a monomicrobic Fusobacterium necrophorum abscess, whereas the others had polymicrobic F. nucleatum abscesses. Despite surgery and a regimen of antibiotic medications and dexamethasone, three patients experienced a paradoxical deterioration 3 days postoperatively that necessitated reevacuation of the lesion. The evacuants observed at that time contained numerous leukocytes but no microorganisms, suggesting intensified inflammation as the likely cause of deterioration. This explanation is supported by literature that fusobacteria strongly activate neutrophils. An analysis of the 2031 anaerobes from blood, wounds, and abscesses showed the considerable virulence of Fusobacterium spp., which were able to enter and/or sustain themselves in the blood circulation. This pattern was similar to that of Clostridium spp., but different from those of Peptostreptococcus spp., Bacteroides spp., and Prevotella spp., which were less invasive but more abundant.

CONCLUSIONS

Some fusobacterial brain abscesses may be associated with a paradoxical postoperative deterioration, which is probably due to intensified inflammation following treatment. The blood-borne dissemination and invasive behavior of fusobacteria likely initiate such a brain abscess, and further seeding of other synergic bacteria leads to a polymicrobic abscess.