h Halicephalobus gingivalis (previously Micronema deletrix) is a free-living nematode known to cause opportunistic infections, mainly in horses. Human infections are very rare, but all cases described to date involved fatal meningoencephalitis. Here we report the first case of H. gingivalis infection in an Australian human patient, confirmed by nematode morphology and sequencing of ribosomal DNA. The implications of this case are discussed, particularly, the need to evaluate real-time PCR as a diagnostic tool.
CASE REPORTA 74-year-old lady from a regional town in the Eyre Peninsula of South Australia with a 4-day history of mental state deterioration, fever, and a loss of coordination was transferred to the Royal Adelaide Hospital. She was moderately immune suppressed by methotrexate and etanercept treatment for rheumatoid arthritis and had a history of diabetes. During the admission, her conscious state deteriorated rapidly, requiring mechanical ventilation and admission to the intensive care unit (ICU). Subsequently, she developed signs of brainstem involvement and exhibited a loss of corneal and gag reflexes. She was administered benzylpenicillin, ceftriaxone, and aciclovir for presumptive meningoencephalitis of bacterial or viral etiology. Cerebrospinal fluid (CSF) obtained by lumbar puncture demonstrated 280 ϫ10 6 polymorphonuclear leukocytes (PMN)/liter, 18 ϫ10 6 mononuclear lymphocytes/liter, elevated CSF protein of 1.59 g/liter, and CSF glucose of 3.3 mmol/ liter; aerobic and anaerobic bacterial culture results were negative, as were PCR results for Streptococcus pneumoniae, Neisseria meningitidis, herpes simplex virus, and varicella-zoster virus. CSF India ink stain and cryptococcal antigen lateral flow assay (Immy, Inc., Norman, OK, USA) results were negative. Magnetic resonance imaging (MRI) of the brain exhibited a left-predominant, asymmetrical meningeal enhancement in the frontoparietal cortex, without any detectable brainstem changes. Two days later, repeated lumbar punctures showed a marked elevation of PMN to 2,500 ϫ10 6 cells/liter and 34 ϫ10 6 mononuclear cells/liter, with no bacteria detected upon Gram staining. CSF stained with DiffQuick (Alere, Brisbane, Australia) showed 99% PMN with very few eosinophils. CSF protein was markedly elevated (5.46 g/liter), and CSF glucose was 1.3 mmol/liter. Microscopic examination of 100 l of unstained CSF was performed after centrifugation at 700 ϫ g for 10 min, but no amoebic trophozoites were detected. With a suspicion of parasitic infection, given the unexplained high PMN counts, the antimicrobial treatment strategy was changed to liposomal amphotericin B, sulfadiazine, pentamidine, and azithromycin to target protists such as amoebae and Toxoplasma gondii. CSF was subjected to PCR for Naegleria fowleri, Acanthamoeba sp., and Balamuthia mandrillaris, but all test results were negative. No anti-Strongyloides serum antibody (IgG) was detected in an enzyme-linked immunosorbent assay using somatic larval antigens from Strongyloides ratti (Bordier Affinity Pr...