Diagnostic value and biological significance of antibody-coated bacteria in urine

Detection of antibody-coated Mucor in skin biopsy by direct immunofluorescence

Cutaneous mucormycosis may be caused by direct inoculation or hematogenous spread of mucormycetes in immunocompromised patients. Skin biopsy is characterized by a deep fungal infection with frequent angioinvasion. The fungal hyphae can usually be identified on H&E stain. We report a case of cutaneous angioinvasive mucormycosis in which the fungi were also visualized on direct immunofluorescence. A 57-year-old patient with relapsed myelodysplastic syndrome status-post allogeneic hematopoietic cell transplant, diabetes mellitus, and graft-versus-host disease presented with painful, palpable, dark-red to violaceous retiform purpuric plaques. Light microscopy of punch biopsy revealed numerous broad, ribbon-like, pauci-septate hyphae in the dermis with angioinvasion, consistent with mucormycosis. Direct immunofluorescence performed on a concurrent biopsy to exclude immune complex vasculitis showed smooth IgG, IgA (weak), IgM (faint), and C3 deposition on the hyphal structures, compatible with antibody-coated fungi. Tissue culture subsequently confirmed Mucor species. Although mucormycosis was readily diagnosable on routine light microscopy in this case, recognition of the unique phenomenon of antibody-coated fungi can be crucial when the invasive fungi are sparse or only present in the direct immunofluorescence specimen.

UTIs in small animal patients: part 1: etiology and pathogenesis

Understanding how urinary tract infections (UTIs) can occur and how to classify them can help the practitioner to make a plan for treatment. This review summarizes the etiology, pathogenesis, and host defense mechanisms associated with bacterial UTIs in dogs and cats. UTIs in Small Animal Patients: Part 2: Diagnosis, Treatment, and Complications will appear in the March/April 2013 issue of the Journal of the American Animal Hospital Association.

Antibody coated bacteria in urine of patients with recent spinal injury

Twenty patients with an acute spinal injury were prospectively studied to assess the clinical importance of antibody coated bacteria (ACB) in the urine and the association among the different bacterial species with a positive antibody coated bacteria test. Clinical urinary tract infection was associated with a positive ACB test on 45% of occasions. Three hundred and ninety nine urine samples containing 541 bacterial isolates were assessed for the presence of ACB; 13% were found to be positive and 87% negative for ACB; 67% of urines contained a single bacterial isolate. Pseudomonas aeruginosa was most commonly associated with clinical urinary tract infection, found in 25% of episodes, followed by Proteus mirabilis (17.5%), Klebsiella sp (12.5%), and Proteus morganii (10%). Providencia stuartii, however, was most commonly associated with a positive ACB test (found in 17%). Other bacteria associated with a positive ACB test included Klebsiella sp (14%), Acinetobacter sp (12.5%), Pseudomonas aeruginosa (12%), Citrobacter sp (11.5%). A positive ACB test is not to be expected from a patient with spinal injury who has a catheter in place, and the test may provide a useful guide to identify those patients with an invasive infection. It is doubtful that a decision to treat or not treat bacteriuria could rest on the identification of the bacterial species alone.