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Journal of Clinical Microbiology, September 2004, p. 4403-4404, Vol. 42, No. 9
0095-1137/04/$08.00+0 DOI: 10.1128/JCM.42.9.4403-4404.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
Rapid Identification of Mycobacterium genavense with a New Commercially Available Molecular Test, INNO-LiPA MYCOBACTERIA v2
François Trueba,1* Michel Fabre,1 and Patrick Saint-Blancard2
Department of Clinical Microbiology,1
Department of Pathology, Percy Hospital, Clamart, France2
Received 14 December 2003/
Returned for modification 2 February 2004/
Accepted 24 February 2004

ABSTRACT
We report a rare mesenteric localized
Mycobacterium genavense infection in a severely immunocompromised human immunodeficiency
virus-infected patient. An INNO-LiPA MYCOBACTERIA v2 test was
performed directly on biopsy samples. This new molecular tool
could be used for simultaneous identification of mycobacterium
species from human specimens, but other studies are needed to
validate our first results.

CASE REPORT
A 39-year-old human immunodeficiency virus type 1 (HIV-1)-infected
homosexual man was referred to our hospital because of a 2-week
history of intermittent left lower quadrant abdominal pain and
constipation. The patient also noticed systemic symptoms, such
as weakness, anorexia, and massive weight loss (12 kg in the
last 2 months), without fever. There was no palpable mass on
abdominal examination. The complete blood count was within the
normal range. The erythrocytic sedimentation rate was 126 mm
in the first hour, and the C-reactive protein level was 85 mg/liter.
Laboratory studies were consistent with advanced immunodepression.
The patient had a significantly decreased number of circulating
CD4
+ T lymphocytes (27 cells/mm
3) and high HIV RNA levels in
plasma (235,000 copies/ml). An enhanced computed tomography
scan of the abdomen revealed a mesenteric mass with a hypodense
center and abdominal lymphadenopathy. The tumor, suspected to
be a lymphoma, was resected. The sample was processed by using
the
N-acetyl-
L-cysteine-sodium hydroxide decontamination procedure,
prior to testing by the Amplified Mycobacterium Tuberculosis
Direct test (Gen-Probe, San Diego, Calif.), and was analyzed
for the presence of inhibitors or interfering substances according
to the manufacturer's instructions (
4). The sample was stained
using the Ziehl-Neelsen method (
9). It was inoculated onto a
solid medium (Löwenstein-Jensen medium) and into a mycobacterial
growth indicator tube (
2). The inoculated culture media were
incubated for a maximum of 8 weeks. Histology of the clinical
specimen showed a macrophagic infiltration, and the Ziehl-Neelsen
stain revealed numerous acid-fast bacilli. No
Mycobacterium tuberculosis complex was identified by Amplified Mycobacterium
Tuberculosis Direct test of the tumor sample. An INNO-LiPA MYCOBACTERIA
v2 test (Innogenetics, Ghent, Belgium) was performed, and
Mycobacterium genavense was identified from sample and from liquid culture.
No stool specimens were tested. A positive growth in the mycobacterial
growth indicator tube 960 system was detected 2 months later.
The outcome was fatal in spite of anti-HIV tritherapy and treatment
with clarithromycin, ethambutol, and rifampin.
M. genavense is a nontuberculous mycobacterium and was first described in 1992 by Böttger et al. (1). It has been identified as a cause of disseminated disease in AIDS patients (6). M. genavense infection should be considered in the differential diagnosis of AIDS patients with CD4 cell counts below 100 cells/mm3 presenting with multiple large retroperitoneal and mesenteric lymph nodes or circumferential wall thickening of the proximal small bowel (3). Realini et al. found that the addition of a polymyxin B, amphotericin B, nalidixic acid, trimethoprim, and azlocillin (PANTA) antibiotic mixture to primary cultures impedes the in vitro growth of M. genavense (5). These bacteria grow poorly in vitro and were detected from liquid medium without the addition of PANTA 8 weeks after inoculation. Diagnosis was established using the new reverse hybridization multiple DNA probe assay INNO-LiPA MYCOBACTERIA v2. Biotinylated DNA material, obtained by means of a PCR amplification of the 16S to 23S rRNA polymorphic spacer region, is hybridized with 23 specific oligonucleotide probes immobilized as parallel lines on membrane strips. The addition of streptavidin labeled with alkaline phosphates and of a chromogenic substrate results in a purple-brown precipitate on hybridized lines (7). The mesenteric tumor biopsy sample had been decontaminated and directly tested without DNA extraction. The number of acid-fast bacilli in the sample and the substantial enlargement of the spectrum of species identifiable by INNO-LiPA MYCOBACTERIA v2 testing allowed us to detect M. genavense. The amplification product from the isolate detected by the test was sequenced. The DNA sequence was identical to the 16S to 23S spacer region sequence for M. genavense from GenBank (accession number Y14183), confirming the INNO-LiPA MYCOBACTERIA v2 result. Liquid medium culture was also tested 2 months after inoculation, and M. genavense was confirmed as the sole etiological agent. A recent evaluation of INNO-LiPA MYCOBACTERIA v2 revealed 100% sensitivity and specificity for the genus-specific probe. For the species-specific probes, the total specificity was 94.4% and the sensitivity was 100% (8). Despite the fact that mycobacterial identification from biopsy samples using INNO-LiPA MYCOBACTERIA v2 is not recommended by the manufacturer, our example demonstrates the role of this new molecular tool, performed on biopsy specimens, for the rapid and simultaneous identification of mycobacterium species. More relevant studies are needed to validate our findings.

FOOTNOTES
* Corresponding author. Mailing address: Percy Hospital, 101 avenue Henri Barbusse, 92141 Clamart cedex, France. Phone: 33 0141466321. Fax: 33 0141466457. E-mail:
f.trueba{at}wanadoo.fr.


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Journal of Clinical Microbiology, September 2004, p. 4403-4404, Vol. 42, No. 9
0095-1137/04/$08.00+0 DOI: 10.1128/JCM.42.9.4403-4404.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
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