Legionella/Legionellosis
Classification General Characteristics Legionella General characteristics: Structure: thin, pleomorphic rods/bacilli Gram stain: gram negative (poor Gram staining) Other stain(s): usually with silver stain Oxygen requirement: aerobic Invasion and replication in relation to host cell(s): facultative intracellular Enzyme(s): Catalase positive Oxidase positive (Legionella pneumophila (L. pneumophila)) Culture medium: grown on buffered charcoal yeast extract (BCYE) medium […]
Campylobacter
Classification General Characteristics Basic features General characteristics of Campylobacter species include: Clinically relevant species Epidemiology Pathogenesis Reservoirs Transmission Pathogenesis factors Clinical Presentation Gastroenteritis Complications (autoimmune) Prevention References
Bacteroides
Classification General Characteristics Basic features Gram-negative bacilli Pleomorphic: appear as either straight rods or coccobacilli 0.5–0.8 μm in diameter and 1.5–4.5 μm long Anaerobes, although tolerate exposure to oxygen Encapsulated Ferment carbohydrates: Including complex plant polysaccharides indigestible to the host Allows for commensal/symbiotic relationship between the bacteria and host Part of indigenous bacterial flora of […]
Leptospira/Leptospirosis
General Characteristics Leptospira Characteristics: A spirochete Structure: Spiral or shaped like a question mark Has hook-shaped ends (differentiates Leptospira from other spirochetes) Oxygen requirement: aerobic Gram stain: gram-negative (stains poorly) Other stain(s): silver stain Microscopy: Best visualized with dark field microscopy Fluorescent microscopy Culture: special media required Associated diseases (zoonosis): Leptospirosis (anicteric) Weil’s disease (icterohemorrhagic) […]
Mycoplasma
General Characteristics Pathogenesis Diseases Caused by Mycoplasma M. pneumoniae Pathology caused by the M. pneumoniae bacterium is varied; however, diagnosis and treatment are standard: Table: Compare and contrast Mycoplasma pneumonia with pneumococcal pneumonia Characteristics Mycoplasma pneumonia Pneumococcal pneumonia Type of pneumonia Atypical (interstitial) Typical (alveolar) Preceding pharyngitis Common Never Onset Gradual Sudden with chills Fever […]
Brucella/Brucellosis
General Characteristics of Brucella General characteristics Gram-negative coccobacilli Facultative intracellular Aerobic Requires carbon dioxide (CO2) Non-motile Unencapsulated Non-spore forming Oxidase and urease positive Require enriched media for culture growth (Thayer-Martin medium) Improved with blood or serum Optimum temperature: 35–37°C (95–98.6°F) Clinically relevant species B. melitensis B. abortus B. suis B. canis Epidemiology and Risk Factors […]
Virology
Definition Viruses are infectious, obligate intracellular parasites, composed of a nucleic acid core (deoxyribonucleic acid (DNA) or ribonucleic acid (RNA)) surrounded by a protein capsid; at times, viruses are also surrounded by an envelope derived from host cell membranes. Structure Basic structure consists of: Inner “machinery” that allows the virus to replicate within host cells […]
Lyme Disease
Overview Epidemiology Etiology Pathophysiology Clinical Presentation The incubation period for Lyme disease is 3–30 days (mean of 7 days). The clinical manifestations of Lyme disease are broken down into 3 stages: early localized disease, early disseminated disease, and late disease. Early localized disease Symptoms appear in 1–5 weeks and resolve in approximately 30 days. Early […]
Pseudomonas
Classification General Characteristics Gram-negative bacilli Encapsulated Motile: 1–3 motile flagella Obligate aerobe Oxidase positive Catalase positive Non-lactose fermenting Produces a blue-green pigment: due to pyocyanin and fluorescein production Produces a characteristic fruity, grape-like odor Clinically relevant species: Pseudomonas aeruginosa (P. aeruginosa) Pathogenesis Reservoir and transmission Reservoir: Ubiquitous in the environment Moist reservoirs: Sinks Respiratory and […]
Nocardia/Nocardiosis
Classification General Characteristics Nocardia Clinically relevant species Epidemiology Pathogenesis Reservoir and transmission Virulence Disease process Host risk factors Clinical Presentation Pulmonary nocardiosis Disseminated nocardiosis Cutaneous nocardiosis Diagnosis and Management Diagnosis Management Comparisons Actinomyces and Nocardia Table: Gram-positive, branching, filamentous rods that must be distinguished Differentiating factors Actinomyces Nocardia Oxygen requirement Anaerobic Aerobic Acid-fast stain Not […]