Section I– Microbiology By Nada Sajet
directly onto media for isolation of fungi.
fluids. For microscopic examination, cytocentrifugation should be used to prepare Gram-stained
acid-fast stain for mycobacteria can also be performed.
periodic acid-Schiff (PAS) staining in addition to Gram stain. Either 10% KOH or calcofluor white is
recommended for visualization of fungal elements from a wet preparation.
Bone: Clotted bone marrow aspirates or biopsies must be homogenized or ground to release trapped
fungal, or parasitic agents. With respect to obtaining specimens from patients suspected of having
Section I– Microbiology By Nada Sajet
useful for directing antibiotic therapy for better clinical outcome.
assays were able to detect a majority of prosthetic joint infections. Atkins
diagnostic sensitivity for infection.
suspension for bacteriologic and mycobacterial cultures.
prereduced anaerobic plates and broth with material from the bone.
samples should also be sent to surgical pathology for histologic examination.
center from surface colonization (growth only at the edge).
certain systemic fungi and mycobacteria.
should be examined by direct fluorescent antibody test for Legionella spp.
Section I– Microbiology By Nada Sajet
Infections of the Lower Respiratory System:
bronchi and bronchioles and then into the alveolar spaces where gas exchange occurs.
extends past the nasopharynx and oropharynx to the trachea and then into the lungs.
exchange structures of the respiratory tract.
the heart and lungs, has three partitions separated from one another by pleura.
mainly by the esophagus, trachea, large blood vessels, and heart.
Pathogenesis of the respiratory tract:
Microorganisms primarily cause disease by a limited number of pathogenic mechanisms. Because these
cause disease (pathogenicity) but also on the human host’s ability to prevent the infection.
organisms from entering the bronchi and gaining access to the
and oropharynx help prevent colonization by pathogenic organisms of the upper respiratory tract.
Section I– Microbiology By Nada Sajet
well as production of bacteriocins and metabolic products that are toxic to invading organisms.
healthy persons, are listed in Table(1).
Under certain circumstances and for unknown reasons, these colonizing organisms can cause disease—
respiratory epithelium (e.g., from smoking).
presence or quantity of white blood cells.
contamination with normal flora should be definitively identified and reported to the clinician.)
( Table 1) Organisms Present in the Nasopharynx and Oropharynx of Healthy Humans:
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