Salmonella bacilli negative image recognized on Diff-Quik stain from pleural fluid cytology

Abstract

Understanding the significance of cytopathological tests in evaluating various infectious processes have become very essential nowadays, as it is a safe, fast, and cost-effective procedure. We present a case of a 52-year-old male with Salmonella empyema where the causative organisms were initially identified on cytology, and subsequently confirmed by microbiological culture. Diff-Quik stained smears showed many colorless, slender, fat short bacilli, which were visualized against the blue-gray background of the smear. These bacilli were identified both intracellularly inside the histiocytes and neutrophils cytoplasm as well as extracellularly in the smear background. We consider that this negative image represents the organism and its capsule creating an area that did not take the Diff-Quik stain. The patient was treated accordingly with suitable antibiotics. A brief discussion of this interesting finding in such a rare infection with pertinent literature review is presented.