title: Not everything acid fast is Mycobacterium tuberculosis--a case report.
abstract: The Ziehl-Neelsen (ZN) stain is important in identifying organisms that are acid fast, principally Mycobacterium tuberculosis. However, decolorisation with a weaker acid concentration (for example 1% hydrochloric acid), often used in ZN staining in histology, can result in a wider variety of organisms appearing acid fast and can be a cause of misidentification. To illustrate this point, a patient is described with pulmonary nocardiosis who was misdiagnosed as having tuberculous empyema on pleural biopsy.
authors.affiliation: Department of Medical Microbiology, St Bartholomew's Hospital, London, UK.
authors.forename: E S
authors.initials: ES
authors.lastname: Olson
authors.forename: A J
authors.initials: AJ
authors.lastname: Simpson
authors.forename: A J
authors.initials: AJ
authors.lastname: Norton
authors.forename: S S
authors.initials: SS
authors.lastname: Das
mesh_terms: D000368:Aged; D004396:Coloring Agents; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D009617:Nocardia Infections / Q000175:diagnosis*; D009616:Nocardia asteroides / Q000302:isolation & purification*; D010994:Pleura / Q000382:microbiology*; D010995:Pleural Diseases / Q000175:diagnosis*; D014396:Tuberculosis, Pleural / Q000175:diagnosis
chemical_list: D004396:Coloring Agents