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Meningitis due to enterotoxigenic Bacteroides fragilis
P Aucher1, J P Saunier, G Grollier
1Laboratoire de Microbiologie A, Centre Hospitalier Universitaire La Milètrie, Poitiers, France.
Abstract:
An enterotoxigenic strain of Bacteroides fragilis was the sole organism isolated from the cerebrospinal fluid of a two-and-a-half-month neonate who had a medullary-colonic fistula as part of a complex congenital malformation, but no brain abscess. A rapid latex particle agglutination test for detection of bacterial antigen was positive for Haemophilus influenzae type b, suggesting that Bacteroides fragilis and Haemophilus influenzae type b might share some capsular antigens. In order to determine the role of the enterotoxin with respect to virulence of the strain, antibodies to a 20 kDa protein were sought in the patient's serum, but Western blot of the culture supernatant revealed only antibodies to a 45 kDa bacterial protein. The patient was successfully treated with metronidazole and imipenem.
Insights
A rare case of Bacteroides fragilis meningitis in a neonate with congenital malformations highlights potential shared antigens with Haemophilus influenzae type b. The study investigated the role of enterotoxin in virulence, finding antibodies to a 45 kDa protein.
Area of Science:
- Neonatal meningitis
- Bacteriology
- Immunology
Background:
- Enterotoxigenic Bacteroides fragilis (ETBF) is a known cause of diarrhea, but rarely associated with invasive infections.
- Neonatal meningitis presents a significant challenge due to immature immune systems and complex congenital anomalies.
- Medullary-colonic fistula is a rare congenital malformation, potentially increasing susceptibility to infections.
Observation:
- A neonate with a complex congenital malformation, including a medullary-colonic fistula, presented with meningitis caused solely by ETBF.
- Cerebrospinal fluid analysis revealed ETBF, with no evidence of brain abscess.
- A latex particle agglutination test for bacterial antigen was positive for Haemophilus influenzae type b, suggesting potential cross-reactivity or shared antigens.
Findings:
- Western blot analysis of the ETBF culture supernatant did not reveal antibodies to a 20 kDa enterotoxin protein in the patient's serum.
- Antibodies to a 45 kDa bacterial protein were detected in the patient's serum, indicating an immune response to a different ETBF component.
- The absence of anti-enterotoxin antibodies suggests the enterotoxin may not have played a direct role in the virulence of this specific ETBF strain in the central nervous system.
Implications:
- This case expands the spectrum of invasive infections caused by ETBF, particularly in neonates with congenital anomalies.
- The positive test for Haemophilus influenzae type b antigen warrants further investigation into shared capsular antigens between ETBF and H. influenzae.
- Successful treatment with metronidazole and imipenem provides valuable clinical information for managing rare ETBF meningitis cases.