Acid‐fast‐positive Legionella pneumophila: A possible pitfall in the cytologic diagnosis of mycobacterial infection in pulmonary specimens

Bentz, Joel S.; Carroll, Karen C.; Ward, John H.; Elstad, Mark R.; Cj, Marshall

doi:10.1002/(sici)1097-0339(200001)22:1<45::aid-dc12>3.3.co;2-p

Cited by 5 publications

(5 citation statements)

References 14 publications

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“…It is also likely that MIFs may have accounted for the positive acid-fast staining (retention of carbol fuchsin after an acidic wash) of Legionella spp. in sputum samples (8,37). While the MIF morphology is readily observed in protozoan hosts (9,57,65), it has not been conspicuous in macrophages.…”

Section: Discussionmentioning

confidence: 99%

Intracellular Growth of Legionella pneumophila Gives Rise to a Differentiated Form Dissimilar to Stationary-Phase Forms

Garduño

Garduño²,

Hiltz³

et al. 2002

Infect Immun

143

242

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When Legionella pneumophila grows in HeLa cells, it alternates between a replicative form and a morphologically distinct "cyst-like" form termed MIF (mature intracellular form). MIFs are also formed in natural amoebic hosts and to a lesser extent in macrophages, but they do not develop in vitro. Since MIFs accumulate at the end of each growth cycle, we investigated the possibility that they are in vivo equivalents of stationaryphase (SP) bacteria, which are enriched for virulence traits. By electron microscopy, MIFs appeared as short, stubby rods with an electron-dense, laminar outer membrane layer and a cytoplasm largely occupied by inclusions of poly-␤-hydroxybutyrate and laminations of internal membranes originating from the cytoplasmic membrane. These features may be responsible for the bright red appearance of MIFs by light microscopy following staining with the phenolic Giménez stain. In contrast, SP bacteria appeared as dull red rods after Giménez staining and displayed a typical gram-negative cell wall ultrastructure. Outer membranes from MIFs and SP bacteria were equivalent in terms of the content of the peptidoglycan-bound and disulfide bond cross-linked OmpS porin, although additional proteins, including Hsp60 (which acts as an invasin for HeLa cells), were detected only in preparations from MIFs. Proteomic analysis revealed differences between MIFs and SP forms; in particular, MIFs were enriched for an ϳ20-kDa protein, a potential marker of development. Compared with SP bacteria, MIFs were 10-fold more infectious by plaque assay, displayed increased resistance to rifampin (3-to 5-fold) and gentamicin (10-to 1,000-fold), resisted detergent-mediated lysis, and tolerated high pH. Finally, MIFs had a very low respiration rate, consistent with a decreased metabolic activity. Collectively, these results suggest that intracellular L. pneumophila differentiates into a cyst-like, environmentally resilient, highly infectious, post-SP form that is distinct from in vitro SP bacteria. Therefore, MIFs may represent the transmissible environmental forms associated with Legionnaires' disease.The genus Legionella is one of the most successful of all aquatic bacteria, consisting of over 40 named species, their numerous serogroups (7), and a collection of Legionella-like amoebal pathogens that usually exhibit an obligate intracellular lifestyle requiring a particular protozoan host (3). An obligate requirement for the amino acid cysteine (38), which cannot be substituted for by cystine (the oxidized form most commonly found in aerobic environments), conceivably limits members of the Legionella genus to an intracellular lifestyle (25,46) or to life in association with other microorganisms (46,56,63,66) that may constitute a source of cysteine. However, in a biofilm coculture model, persistence but not multiplication of legionellae could be strictly demonstrated, suggesting that natural growth may indeed require the intracellular environment of a protozoan host (52). Thus, the natural life cycle of Legionella most likely...

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Section: Discussionmentioning

confidence: 99%

Intracellular Growth of Legionella pneumophila Gives Rise to a Differentiated Form Dissimilar to Stationary-Phase Forms

Garduño

Garduño²,

Hiltz³

et al. 2002

Infect Immun

143

242

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“…3 Of note, certain species of Legionella are acid-fast positive and must be differentiated from mycobacterial organisms. 15 Occasionally, FNA (transbronchial or computed tomography guided) is performed for evaluation of parenchymal lung lesions when the differential diagnosis includes neoplasm versus infection. In these cases, the identification of bacterial organisms is much more meaningful than in sputum or bronchial washing and brushing samples, which are readily contaminated with bacterial from the upper aerodigestive tract.…”

Section: Bacterial Infectionsmentioning

confidence: 99%

Diagnosis of Infectious Diseases in the Lower Respiratory Tract: A Cytopathologist's Perspective

Baldassarri

Kumar

Baldassarri

et al. 2018

Archives of Pathology &Amp; Laboratory Medicine

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- The lower respiratory tract is subject to infection by a wide variety of infectious agents. Pathologists should be familiar with common organisms, including their general clinical characteristics, cytomorphologic features, differential diagnoses, and ancillary methods of detection. Above all, correlation with microbiologic and clinical information is necessary to make a confident diagnosis of infection.

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“…BAL for Legionella DNA (16S rRNA gene) by PCR, direct fluorescent antibody test, and culture may complement urine antigen testing(141). L. pneumophila may also stain acid-fast positive(142) Leptospirosis DAH may occur with minimal or no apparent abnormality on chest radiograph and with or without renal or hepatic involvement. No definitive data on differential cell count although histopathologic findings indicate relatively modest infiltration of alveolar spaces with monocytes and neutrophils.…”

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confidence: 99%

Bronchoalveolar lavage as a diagnostic procedure: a review of known cellular and molecular findings in various lung diseases

Davidson

Schwarz

et al. 2020

J Thorac Dis

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Bronchoalveolar lavage (BAL) is a commonly used procedure in the evaluation of lung disease as it allows for sampling of the lower respiratory tract. In many circumstances, BAL differential cell counts have been reported to be typical of specific lung disorders. In addition, more specific diagnostic tests including molecular assays such as polymerase chain reaction (PCR) or enzyme-linked immunosorbent assay, special cytopathologic stains, or particular microscopic findings have been described as part of BAL fluid analysis. This review focuses on common cellular and molecular findings of BAL in a wide range of lung diseases.Since the performance of the first lung irrigation in 1927, BAL has become a common and important diagnostic tool. While some pulmonary disorders have a highly characteristic signature of BAL findings, BAL results alone often lack specificity and require interpretation along with other clinical and radiographic details. Development of new diagnostic assays is certain to reinforce the utility of BAL in the future. Our review of the BAL literature is intended to serve as a resource to assist clinicians in the care of patients with lung disorders.

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Acid‐fast‐positive Legionella pneumophila: A possible pitfall in the cytologic diagnosis of mycobacterial infection in pulmonary specimens

Cited by 5 publications

References 14 publications

Intracellular Growth of Legionella pneumophila Gives Rise to a Differentiated Form Dissimilar to Stationary-Phase Forms

Intracellular Growth of Legionella pneumophila Gives Rise to a Differentiated Form Dissimilar to Stationary-Phase Forms

Diagnosis of Infectious Diseases in the Lower Respiratory Tract: A Cytopathologist's Perspective

Bronchoalveolar lavage as a diagnostic procedure: a review of known cellular and molecular findings in various lung diseases

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