Legionella is a facultative intracellular Facultative intracellular Yersinia spp./Yersiniosis, gram-negative bacilli Bacilli Shigella. Legionella does not grow on common culture media because it requires certain supplementation ( cysteine Cysteine A thiol-containing non-essential amino acid that is oxidized to form cystine. Synthesis of Nonessential Amino Acids and iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements). Legionella can be isolated on a buffered charcoal Charcoal An amorphous form of carbon prepared from the incomplete combustion of animal or vegetable matter, e.g., wood. The activated form of charcoal is used in the treatment of poisoning. Antidotes of Common Poisonings yeast Yeast A general term for single-celled rounded fungi that reproduce by budding. Brewers' and bakers' yeasts are saccharomyces cerevisiae; therapeutic dried yeast is yeast, dried. Mycology extract (BCYE) medium. The habitat for Legionella is aquatic systems including human-constructed reservoirs, such as cooling towers and hot water tanks. Transmission occurs primarily through inhalation of aerosolized water droplets Droplets Varicella-Zoster Virus/Chickenpox, causing pulmonary infection. Legionella pneumophila (L. pneumophila) accounts for the majority of human infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease. The clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor includes Legionnaires’ disease, atypical pneumonia Atypical pneumonia Mycoplasma, and Pontiac fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever. Diagnosis is by culture, urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination test, and/or polymerase chain reaction Polymerase chain reaction Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) ( PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR)). Fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones and macrolides Macrolides Macrolides and ketolides are antibiotics that inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit and blocking transpeptidation. These antibiotics have a broad spectrum of antimicrobial activity but are best known for their coverage of atypical microorganisms. Macrolides and Ketolides are the main treatments.
Last updated: 16 Feb, 2021
Gram-negative
bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology:
Most
bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology can be classified according to a lab procedure called
Gram staining
Gram staining
Bacteriology.
Bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology with cell walls that have a thin layer of
peptidoglycan
Peptidoglycan
Penicillins do not retain the crystal violet stain utilized in
Gram staining
Gram staining
Bacteriology. These
bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology do, however, retain the safranin counterstain and thus appear as pinkish-red on the stain, making them
gram negative
Gram negative
Bacteria which lose crystal violet stain but are stained pink when treated by gram’s method.
Yersinia spp./Yersiniosis. These
bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology can be further classified according to morphology (diplococci, curved rods,
bacilli
Bacilli
Shigella, and coccobacilli) and their ability to grow in the presence of oxygen (aerobic versus anaerobic). The
bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology can be more narrowly identified by growing them on specific media (
triple sugar iron
Triple sugar iron
Shigella (
TSI
TSI
Shigella) agar) where their
enzymes
Enzymes
Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules.
Basics of Enzymes can be identified (
urease
Urease
An enzyme that catalyzes the conversion of urea and water to carbon dioxide and ammonia.
Nocardia/Nocardiosis,
oxidase
Oxidase
Neisseria) and their ability to ferment lactose can be tested.
* Stains poorly on
Gram stain
Gram stain
Klebsiella
**
Pleomorphic
Pleomorphic
Bacteroides rod/coccobacillus
*** Require special transport media
A silver stain of L. pneumophila
Image: “Legionella Silver Stain” by William Cherry. License: Public domain.Pathogenesis of Legionella infection
The
bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology are opsonized by C3b (a cleaved component of C3) and are incorporated into the
macrophages
Macrophages
The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells.
Innate Immunity: Phagocytes and Antigen Presentation. Once inside the phagosome, the Legionella inhibits phagolysosomal fusion, which allows growth of the
bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology, producing degradative
enzymes
Enzymes
Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules.
Basics of Enzymes and toxins, eventually leading to
apoptosis
Apoptosis
A regulated cell death mechanism characterized by distinctive morphologic changes in the nucleus and cytoplasm, including the endonucleolytic cleavage of genomic DNA, at regularly spaced, internucleosomal sites, I.e., DNA fragmentation. It is genetically-programmed and serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
Ischemic Cell Damage of the infected cell. The destroyed cell releases the
bacteria
Bacteria
Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.
Bacteriology, spreading the infection to other cells.
Infection with Legionella is known as legionellosis.
Pontiac fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever | Legionnaires’ disease | |
---|---|---|
Infection rate | > 90% | < 5% |
Time of onset | Throughout the year | Sporadic Sporadic Selective IgA Deficiency cases or outbreaks Outbreaks Sudden increase in the incidence of a disease. The concept includes epidemics and pandemics. Influenza Viruses/Influenza in late summer and early autumn |
Incubation Incubation The amount time between exposure to an infectious agent and becoming symptomatic. Rabies Virus period | 1–2 days | 2–10 days |
Manifestations |
|
|
Resolution |
|
|
Mortality rate Mortality rate Calculated as the ratio of the total number of people who die due to all causes over a specific time period to the total number of people in the selected population. Measures of Health Status | < 1% | 15%–20% (if untreated) |
Legionella pneumophila: direct immunofluorescence staining with fluorescence-labeled antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions
Image: “Legionella Pneumophila IF” by CDC-PHIL. License: Public domain.Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests of a patient with L. anisa pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia: Image shows right base infiltrates (arrow).
Image: “PMC4956277_pone.0159726.g002” by Vaccaro L, Izquierdo F, Magnet A, Hurtado C, Salinas MA, Gomes TS, Angulo S, Salso S, Pelaez J, Tejeda MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction, Alhambra A, GĂłmez C, EnrĂquez A, Estirado E, Fenoy S, & Del Aguila C. License: CC BY 4.0.Various stages of Legionnaire’s disease in a 42-year-old man with severe
pneumonia
Pneumonia
Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy.
Pneumonia caused by L. pneumophila serogroup 11a
A: chest radiograph and B:
high-resolution CT
High-resolution CT
Imaging of the Lungs and Pleura at hospital admission; C and D: repeat
high-resolution CT
High-resolution CT
Imaging of the Lungs and Pleura of the chest a week after hospital admission