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Microbiology
Table of Contents
Unit 22 Overview: Respiratory System Infections
22.1 Anatomy and Normal Microbiota of the Respiratory Tract
22.2 Bacterial Infections of the Respiratory Tract
22.3 Viral Infections of the Respiratory Tract
22.4 Respiratory Mycoses

🦠microbiology review

22.2 Bacterial Infections of the Respiratory Tract

Citation:

Bacterial respiratory infections can wreak havoc on our airways. From strep throat to pneumonia and tuberculosis, these pathogens use clever tricks to colonize, invade, and evade our defenses. Understanding their strategies is key to fighting back.

Diagnosing these infections requires a mix of old-school and cutting-edge techniques. Cultures help identify the culprit, while serological tests detect our body's response. Molecular methods like PCR offer quick, precise results to guide treatment and track antibiotic resistance.

Bacterial Pathogens and Diseases of the Respiratory Tract

Key pathogens of respiratory infections

  • Strep throat
    • Caused by the bacterium Streptococcus pyogenes (Group A strep) which invades the throat and tonsils
    • Symptoms include severe sore throat, high fever, swollen lymph nodes in the neck, and white patches or streaks of pus on the tonsils
    • Treatment involves a course of penicillin or amoxicillin antibiotics to eliminate the infection and prevent complications (rheumatic fever)
  • Pneumonia
    • Bacterial pathogens that commonly cause pneumonia include Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus which infect the lungs
    • Symptoms of bacterial pneumonia include a productive cough with mucus, chest pain, high fever, difficulty breathing, and fatigue
    • Treatment consists of antibiotics such as amoxicillin or doxycycline to clear the infection along with supportive care measures (oxygen therapy, fluids)
  • Tuberculosis (TB)
    • Caused by the slow-growing bacterium Mycobacterium tuberculosis which primarily affects the lungs but can spread to other organs
    • Symptoms of active TB include a chronic cough lasting more than 3 weeks, fever, night sweats, unintended weight loss, and coughing up blood (hemoptysis)
    • Treatment requires a combination of antibiotics taken for 6-9 months, including isoniazid, rifampin, ethambutol, and pyrazinamide to effectively kill the bacteria

Bacterial colonization of respiratory tract

  • Adherence and colonization
    • Bacterial surface proteins called adhesins bind to specific receptors on respiratory epithelium, allowing the bacteria to attach and establish colonies
    • Examples of adhesins include the M protein of S. pyogenes and the pili of S. pneumoniae which facilitate adherence to throat and lung cells respectively
  • Invasion and spread
    • Certain bacterial pathogens can invade the epithelial cells or penetrate into the subepithelial tissues to cause more extensive infection
    • S. pneumoniae produces a toxin called pneumolysin which forms pores in cell membranes, leading to cell lysis and spread of the bacteria
  • Evasion of host defenses
    • Some respiratory bacteria have polysaccharide capsules that surround their cell wall and help resist phagocytosis by immune cells (S. pneumoniae, H. influenzae)
    • M. tuberculosis can survive inside macrophages by preventing the fusion of phagosomes with lysosomes, thus avoiding destruction by lysosomal enzymes
  • Induction of host inflammatory responses
    • Components of the bacterial cell wall, such as lipoteichoic acid, stimulate the production of inflammatory cytokines by host immune cells
    • Excessive inflammation in response to the bacterial infection contributes to tissue damage, fluid accumulation, and the symptoms of respiratory disease

Host defense mechanisms and bacterial strategies

  • Mucociliary clearance: The respiratory tract's first line of defense, where mucus traps pathogens and cilia move them out of the airways
  • Alveoli: These tiny air sacs in the lungs are crucial for gas exchange but can become sites of infection if bacteria overcome initial defenses
  • Biofilms: Some respiratory pathogens form these structured communities on surfaces, providing protection from host defenses and antibiotics
  • Antibiotic resistance: Bacteria can develop mechanisms to survive antibiotic treatment, complicating the management of respiratory infections

Diagnostics for respiratory pathogens

  • Culture methods
    • Considered the gold standard for diagnosing bacterial respiratory infections by isolating and identifying the causative pathogen
    • Samples of sputum, bronchoalveolar lavage fluid, or pleural fluid are cultured on selective media to grow the bacteria
    • Cultured isolates can be tested for antibiotic susceptibility to guide appropriate treatment
  • Serological tests
    • These tests detect antibodies produced by the patient's immune system against specific bacterial antigens in serum samples
    • Examples include the anti-streptolysin O (ASO) test for recent S. pyogenes infection and the tuberculin skin test for exposure to M. tuberculosis
    • Serological tests are useful for infections that have a delayed antibody response or when direct detection of the pathogen is difficult
  • Molecular techniques
    • Polymerase chain reaction (PCR) is a molecular method that amplifies specific bacterial DNA sequences from clinical samples for rapid and sensitive detection
    • Multiplex PCR assays can simultaneously detect multiple common respiratory pathogens, such as S. pneumoniae, H. influenzae, and Moraxella catarrhalis
    • The GeneXpert MTB/RIF assay is a PCR test that detects M. tuberculosis DNA and resistance to the antibiotic rifampin in sputum samples within 2 hours

Key Terms to Review (114)

Actinobacteria: Actinobacteria are a group of Gram-positive bacteria known for their high G+C content in their DNA. They play crucial roles in soil ecosystems, human health, and the production of antibiotics.
β-lactams: β-lactams are a class of broad-spectrum antibiotics that contain a β-lactam ring in their molecular structure. They work by inhibiting the synthesis of bacterial cell walls, leading to cell death.
A-B toxin: A-B toxins are a class of bacterial exotoxins consisting of two components: the A (active) subunit, which disrupts cell function, and the B (binding) subunit, which facilitates entry into host cells. These toxins are key virulence factors in several pathogenic bacteria causing respiratory infections.
A-B exotoxin: A-B exotoxins are a class of bacterial toxins composed of two subunits: the A subunit, which is enzymatically active, and the B subunit, which binds to host cell receptors. These toxins disrupt cellular functions and can cause severe damage to respiratory tissues.
Adhesins: Adhesins are surface structures on pathogens that allow them to adhere to host cells. They play a crucial role in the initial stages of microbial infection.
Adhesin: Adhesins are specialized proteins expressed by pathogens to attach to host cells. They play a crucial role in the initial stages of infection by binding to specific receptors on the host cell surface.
Acute glomerulonephritis: Acute glomerulonephritis is a rapid-onset inflammation of the glomeruli in the kidneys. It is often caused by immune responses to infections, including bacterial infections.
Acute otitis media: Acute otitis media is a rapid-onset infection of the middle ear, often caused by bacteria. It typically results in ear pain, fever, and hearing difficulties.
Alveoli: Alveoli are tiny air sacs located in the lungs where gas exchange occurs between the air and the blood. They play a critical role in respiration by allowing oxygen to enter the bloodstream and carbon dioxide to be expelled.
AOM: Acute Otitis Media (AOM) is a bacterial infection affecting the middle ear, often following an upper respiratory tract infection. It is characterized by ear pain, fever, and sometimes fluid drainage from the ear.
Autolysin: Autolysins are enzymes produced by bacteria that hydrolyze the components of their own cell walls, leading to cell lysis. They play a crucial role in bacterial cell growth, division, and pathogenesis.
BCG vaccine: The BCG vaccine is a live attenuated vaccine derived from Mycobacterium bovis, primarily used to prevent tuberculosis (TB). It is especially effective against severe forms of TB in children.
Bordet-Gengou medium: Bordet-Gengou medium is a specialized agar used to cultivate Bordetella pertussis, the bacterium responsible for whooping cough. It contains potato, blood, and glycerol to support bacterial growth.
Bordetella pertussis: Bordetella pertussis is a Gram-negative, aerobic coccobacillus that causes whooping cough, a highly contagious respiratory disease. It primarily infects the trachea and bronchi by producing toxins that paralyze the respiratory cilia.
Catarrhal stage: The catarrhal stage is the initial phase of whooping cough (pertussis) characterized by symptoms similar to a common cold, such as runny nose, sneezing, mild cough, and low-grade fever. This stage typically lasts for one to two weeks before progressing to more severe stages.
Carditis: Carditis is the inflammation of the heart or its surrounding tissues. It can be caused by bacterial infections that may originate from respiratory tract infections.
Cephalosporin: Cephalosporins are a class of β-lactam antibiotics that inhibit bacterial cell wall synthesis, effective against a broad spectrum of bacteria. They are commonly used to treat infections in the respiratory, digestive, and circulatory systems.
Chlamydophila pneumoniae: Chlamydophila pneumoniae is a species of bacteria that causes respiratory tract infections, including atypical pneumonia. It is an obligate intracellular pathogen affecting humans.
Chlamydophila psittaci: Chlamydophila psittaci is a Gram-negative bacterium that causes psittacosis, a zoonotic infectious disease primarily transmitted from birds to humans. It affects the respiratory system and can lead to severe pneumonia if untreated.
Chocolate agar: Chocolate agar is an enriched growth medium used for culturing fastidious bacteria, particularly those found in the respiratory tract. It contains lysed red blood cells, which provide necessary nutrients.
Collagenase: Collagenase is an enzyme produced by certain bacteria that breaks down collagen, a major structural protein in connective tissues. This enzymatic activity aids in the spread of infection by degrading host tissue barriers.
Corynebacterium diphtheriae: Corynebacterium diphtheriae is a Gram-positive, non-motile bacterium that causes diphtheria, a serious respiratory disease. It produces a potent exotoxin that inhibits protein synthesis in host cells.
Convalescence stage: The convalescence stage is the period of recovery following an illness or infection, where the patient regains strength and returns to normal health. Symptoms gradually diminish during this phase, but the pathogen may still be present.
Coxiella burnetii: Coxiella burnetii is a small, obligate intracellular bacterium that causes Q fever. It primarily infects the respiratory system of humans through inhalation of contaminated aerosols.
Cystic fibrosis: Cystic fibrosis (CF) is a genetic disorder that affects the respiratory and digestive systems, caused by mutations in the CFTR gene. It leads to thick, sticky mucus production, which obstructs airways and promotes bacterial infections.
Cytokines: Cytokines are small proteins released by cells, especially those of the immune system, that have a specific effect on interactions and communications between cells. They play crucial roles in regulating immune responses and inflammation.
Diphtheria toxin: Diphtheria toxin is a potent exotoxin produced by Corynebacterium diphtheriae that inhibits protein synthesis in host cells, leading to cell death. It is primarily responsible for the symptoms and severity of diphtheria infection.
Diphtheria: Diphtheria is a serious bacterial infection caused by Corynebacterium diphtheriae, affecting the mucous membranes of the respiratory tract. It produces a toxin leading to severe respiratory issues and can be fatal if untreated.
DPT vaccine: The DPT vaccine is a combination vaccine that protects against diphtheria, pertussis (whooping cough), and tetanus. It is crucial in preventing these serious bacterial infections, particularly in children.
DTaP: DTaP is a combination vaccine that protects against three serious bacterial infections: Diphtheria, Tetanus, and Pertussis (whooping cough). It is commonly administered to children as part of their routine immunization schedule.
Escherichia coli: Escherichia coli (E. coli) is a Gram-negative, rod-shaped bacterium commonly found in the intestines of warm-blooded organisms. While most strains are harmless, some can cause serious food poisoning and infections.
Erythrogenic toxin: Erythrogenic toxin is an exotoxin produced by certain strains of Streptococcus pyogenes. It is responsible for the rash in scarlet fever and can act as a superantigen, leading to an exaggerated immune response.
Ghon complexes: Ghon complexes are lesions found in the lungs of individuals infected with Mycobacterium tuberculosis. They consist of a calcified focus of infection and an associated lymph node.
Group B Streptococcus: Group B Streptococcus (GBS) is a type of bacterial infection that can cause serious respiratory tract infections, particularly in newborns and immunocompromised individuals. It is commonly found in the gastrointestinal and genitourinary tracts of healthy adults.
H. influenzae: Haemophilus influenzae (H. influenzae) is a gram-negative coccobacillus bacterium that can cause respiratory tract infections. It is particularly known for causing diseases such as pneumonia, epiglottitis, and meningitis.
Group A streptococci: Group A streptococci (GAS) are Gram-positive bacteria that commonly cause infections in the respiratory tract, such as pharyngitis and tonsillitis. They are known for their ability to produce toxins that contribute to disease severity.
Haemophilus influenzae: Haemophilus influenzae is a Gram-negative bacterium that can cause various infections, particularly in the respiratory tract. It is known for causing severe diseases such as meningitis and pneumonia, especially in young children and immunocompromised individuals.
Hydroxychloroquine: Hydroxychloroquine is an antimalarial drug that also exhibits anti-inflammatory and antiviral properties. It has been used in various treatments, including respiratory infections caused by bacteria and viruses.
Hyaluronidase: Hyaluronidase is an enzyme that breaks down hyaluronic acid, a component of the extracellular matrix. This activity facilitates the spread of pathogens through tissues.
Intubation: Intubation is the medical procedure of inserting a tube into the trachea to maintain an open airway, often essential during severe respiratory infections or surgeries. It ensures that patients receive adequate oxygenation and ventilation.
Klebsiella pneumoniae: Klebsiella pneumoniae is a Gram-negative, encapsulated bacterium that can cause severe infections, particularly in the lungs and urinary tract. It is known for its resistance to multiple antibiotics, making infections difficult to treat.
Lancefield: Lancefield classification is a system used to categorize certain types of bacteria, particularly streptococci, based on the carbohydrate composition of bacterial antigens found on their cell walls. This system is crucial for identifying pathogenic species and understanding their role in infections.
Legionnaires disease: Legionnaires' disease is a severe form of pneumonia caused by the bacterium Legionella pneumophila. It primarily affects the lungs and can be fatal if not treated promptly.
Legionella pneumophila: Legionella pneumophila is a Gram-negative bacterium that is the primary cause of Legionnaires' disease, a severe form of pneumonia. It thrives in aquatic environments and can infect humans through inhalation of contaminated water droplets.
Mantoux tuberculin skin test: The Mantoux tuberculin skin test is a diagnostic tool used to detect latent Mycobacterium tuberculosis infection. It involves the intradermal injection of purified protein derivative (PPD) and measuring the induration at the injection site after 48-72 hours.
Miliary tuberculosis: Miliary tuberculosis is a form of tuberculosis characterized by a wide dissemination into the human body and tiny nodules resembling millet seeds in the affected organs. It can affect multiple organ systems and is often diagnosed through imaging and laboratory tests.
Middle ear: The middle ear is an air-filled cavity within the temporal bone, situated between the outer ear and the inner ear. It contains three tiny bones (ossicles) that transmit sound vibrations from the eardrum to the inner ear.
Mucociliary escalator: The mucociliary escalator is a defense mechanism in the respiratory tract where mucus traps inhaled particles and cilia move them upwards towards the throat to be expelled or swallowed. This process helps keep the respiratory tract clear of pathogens and debris.
Mycobacterium tuberculosis: Mycobacterium tuberculosis is a pathogenic bacterial species in the Mycobacteriaceae family, responsible for causing tuberculosis (TB). It primarily affects the lungs but can also infect other parts of the body.
Mycoplasma pneumonia: Mycoplasma pneumonia is a type of bacterial infection that primarily affects the respiratory tract, leading to atypical pneumonia. It is caused by the bacterium Mycoplasma pneumoniae, which lacks a cell wall.
Otitis media with effusion (OME): Otitis media with effusion (OME) is an accumulation of fluid in the middle ear without signs of acute infection. It commonly occurs in children and can lead to hearing impairment if untreated.
Paroxysmal stage: The paroxysmal stage is a phase of pertussis (whooping cough) characterized by severe coughing fits. These episodes can cause difficulty breathing and often end with a high-pitched 'whoop' sound.
Penicillin: Penicillin is a group of antibiotics derived from Penicillium fungi. It is widely used to treat bacterial infections by inhibiting cell wall synthesis.
Pertussis: Pertussis, also known as whooping cough, is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. It is characterized by severe coughing fits that can last for weeks.
Pertussis toxin (PT): Pertussis toxin (PT) is a protein exotoxin produced by the bacterium Bordetella pertussis, which causes whooping cough. It interferes with normal cellular signaling, leading to increased mucus production and immune system disruption.
Phage conversion: Phage conversion is a process where a bacterium acquires new traits due to the integration of prophage DNA into its genome. This can result in changes such as increased virulence or antibiotic resistance.
Pneumococcal conjugate vaccine: The pneumococcal conjugate vaccine (PCV) is a vaccine designed to protect against Streptococcus pneumoniae, which can cause severe respiratory infections like pneumonia. It contains purified capsular polysaccharide antigens of the bacterium conjugated to a protein carrier to enhance immunogenicity in children.
Pleurisy: Pleurisy is the inflammation of the pleura, the membrane surrounding the lungs and lining the chest cavity, often caused by bacterial infections. It results in sharp chest pain that worsens during breathing.
Pneumolysin O: Pneumolysin O is a toxin produced by Streptococcus pneumoniae that can damage host cell membranes and disrupt immune responses. It plays a crucial role in the pathogenesis of pneumococcal diseases.
Pneumococcal polysaccharide vaccine: The pneumococcal polysaccharide vaccine (PPSV23) protects against 23 types of Streptococcus pneumoniae bacteria. It is primarily used to prevent infections like pneumonia, meningitis, and sepsis.
Pseudomembrane: A pseudomembrane is a layer of exudate resembling a membrane, which forms on mucous membranes during infections. It is commonly associated with bacterial infections like diphtheria.
Q fever: Q fever is a bacterial infection caused by Coxiella burnetii, which primarily affects the respiratory system. It can be transmitted to humans through inhalation of contaminated aerosols from infected animals.
Pseudomonas aeruginosa: Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen that can cause serious infections in humans. It is known for its resistance to antibiotics and ability to thrive in various environments.
Psittacosis: Psittacosis is a bacterial infection caused by Chlamydia psittaci, primarily transmitted to humans from birds. It can lead to respiratory symptoms such as fever, cough, and pneumonia.
Quellung reaction: The Quellung reaction is a biochemical reaction used to identify certain bacterial species, particularly Streptococcus pneumoniae, by causing their capsules to swell when exposed to specific antisera. It is commonly used in microbiology labs for typing capsulated bacteria.
Reactivation tuberculosis: Reactivation tuberculosis (TB) occurs when latent Mycobacterium tuberculosis infection becomes active again, usually due to weakened immunity. It primarily affects the lungs but can also impact other organs.
Rhinosinusitis: Rhinosinusitis is the inflammation of the nasal cavity and paranasal sinuses, typically caused by infections. It can be acute or chronic, affecting respiratory function and causing significant discomfort.
Rhinitis: Rhinitis is the inflammation of the nasal mucous membranes, often resulting in symptoms such as sneezing, nasal congestion, and runny nose. It can be caused by infections, allergens, or other irritants.
Rifampin: Rifampin is an antibiotic commonly used to treat bacterial infections, including tuberculosis and certain types of meningitis. It inhibits RNA synthesis by binding to the bacterial DNA-dependent RNA polymerase.
Scarlet fever: Scarlet fever is an infectious disease caused by the bacterium Streptococcus pyogenes, characterized by a red rash and high fever. It primarily affects children and can have serious complications if untreated.
Sequelae: Sequelae are the long-term consequences that follow an acute illness or infection. They can affect various organs and systems in the body even after the primary infection has been resolved.
Serum sickness: Serum sickness is a type III hypersensitivity reaction that occurs when the immune system reacts to proteins in antiserum derived from non-human sources. It commonly presents with symptoms such as fever, rash, joint pain, and swelling.
Sinusitis: Sinusitis is the inflammation or swelling of the tissue lining the sinuses, often caused by infections. It can be classified as acute, subacute, chronic, or recurrent based on its duration and frequency.
Streptococcal pharyngitis: Streptococcal pharyngitis, commonly known as strep throat, is an infection of the throat and tonsils caused by group A Streptococcus bacteria. It is characterized by a sore, scratchy throat and can lead to complications if untreated.
Streptococcus pyogenes: Streptococcus pyogenes is a Gram-positive bacterium responsible for various infections in humans. It is known for causing diseases such as strep throat, scarlet fever, and rheumatic fever.
Streptolysin: Streptolysin is a type of exotoxin produced by Streptococcus bacteria, particularly Group A Streptococcus. It plays a significant role in the pathogenesis of various respiratory infections.
Streptococcus pneumoniae: Streptococcus pneumoniae is a Gram-positive bacterium often found in the human respiratory tract, capable of causing diseases such as pneumonia, meningitis, and sinusitis. It exhibits virulence factors like a polysaccharide capsule that help it evade the immune system.
Streptococcal toxic shock syndrome (STSS): Streptococcal Toxic Shock Syndrome (STSS) is a severe illness caused by Streptococcus pyogenes, characterized by sudden onset of shock and organ failure. It often starts with respiratory tract infections and rapidly progresses to systemic involvement.
Streptokinase: Streptokinase is an enzyme produced by certain strains of streptococci bacteria. It functions by breaking down blood clots through the conversion of plasminogen to plasmin.
Strep throat: Strep throat is a bacterial infection caused by Streptococcus pyogenes, characterized by inflammation and pain in the throat. It is highly contagious and spreads through respiratory droplets.
Strawberry tongue: Strawberry tongue is a condition characterized by a red, bumpy appearance of the tongue, resembling the surface of a strawberry. It is often associated with certain bacterial infections, particularly those affecting the respiratory tract.
Staphylococcus aureus: Staphylococcus aureus is a Gram-positive bacterium commonly found on the skin and in the nasal passages. It can cause a range of infections from minor skin conditions to severe diseases like pneumonia and sepsis.
Tdap vaccine: The Tdap vaccine is a combination vaccine that protects against tetanus, diphtheria, and pertussis (whooping cough). It is typically administered to adolescents and adults to boost immunity against these bacterial infections.
Thallium acetate: Thallium acetate is a chemical compound used in microbiology for its selective toxicity towards certain bacterial species. It's often employed to isolate and study specific pathogens in respiratory tract infections.
Tubercles: Tubercles are small, rounded nodules that form in the lungs as a result of bacterial infections such as tuberculosis. These structures consist of aggregated immune cells attempting to contain the infection.
Tuberculosis: Tuberculosis (TB) is a contagious bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs but can spread to other organs.
Whooping cough: Whooping cough, also known as pertussis, is a highly contagious bacterial infection of the respiratory tract caused by Bordetella pertussis. It is characterized by severe coughing fits followed by a high-pitched 'whoop' sound during inhalation.
Warthin-Starry silver-precipitate procedure: The Warthin-Starry silver-precipitate procedure is a histological staining method used to detect certain bacteria in tissue samples, particularly those responsible for respiratory infections. It utilizes silver nitrate to stain the organisms, making them visible under a microscope.
Adhesins: Adhesins are specialized surface molecules found on the cells of many pathogens that enable them to attach to and infect host cells. They act as the 'sticky' components that facilitate the initial stages of pathogenesis by allowing the pathogen to bind to and invade the host's tissues.
Rifampin: Rifampin is a broad-spectrum antibiotic used to treat various bacterial infections. It is particularly effective against mycobacterial infections, such as tuberculosis, and is a key component in the treatment of these diseases. Rifampin's mechanism of action and its role in drug resistance and respiratory tract infections make it a crucial topic in the study of microbiology.
Cytokines: Cytokines are a diverse group of small proteins secreted by various cells, primarily immune cells, that act as signaling molecules to coordinate and regulate immune responses, inflammation, and other physiological processes. They play a crucial role in cellular defenses, pathogen recognition, inflammation, adaptive immunity, and various immune-related disorders and conditions.
Pneumolysin: Pneumolysin is a potent virulence factor produced by the bacterium Streptococcus pneumoniae, a leading cause of respiratory tract infections. It is a pore-forming toxin that disrupts host cell membranes, contributing to the pathogenesis of pneumococcal diseases.
Alveoli: Alveoli are the tiny, air-filled sacs located at the end of the respiratory tree within the lungs. They are the primary site of gas exchange, where oxygen is taken in and carbon dioxide is expelled, and are crucial for the respiratory system's normal function and microbiota.
Ethambutol: Ethambutol is a medication primarily used to treat tuberculosis (TB) infections. It works by inhibiting the synthesis of the bacterial cell wall, which is essential for the survival and growth of Mycobacterium tuberculosis, the causative agent of TB.
Pyrazinamide: Pyrazinamide is a first-line antibiotic drug used in the treatment of tuberculosis. It is particularly effective against dormant Mycobacterium tuberculosis bacteria, making it a crucial component of combination therapy for tuberculosis infections.
Tuberculin Skin Test: The tuberculin skin test, also known as the Mantoux test, is a diagnostic procedure used to detect the presence of tuberculosis (TB) infection in individuals. It is a widely used tool for screening and identifying individuals who have been exposed to the Mycobacterium tuberculosis bacteria, the causative agent of tuberculosis.
Mucociliary Clearance: Mucociliary clearance is a crucial defense mechanism in the respiratory system that helps remove foreign particles, microorganisms, and other harmful substances from the airways. It involves the coordinated action of mucus production and the beating of cilia, tiny hair-like projections on the surface of airway epithelial cells.
Sputum: Sputum refers to the mucus and other substances that are coughed up from the lower respiratory tract, including the lungs, bronchi, and trachea. It is an important indicator of respiratory health and can provide valuable information about underlying medical conditions.
Anti-streptolysin O: Anti-streptolysin O (ASO) is an antibody produced by the human body in response to an infection caused by the bacterium Streptococcus pyogenes, also known as group A Streptococcus (GAS). This antibody is commonly used as a diagnostic marker to detect and monitor streptococcal infections, particularly those affecting the respiratory tract.
GeneXpert MTB/RIF: GeneXpert MTB/RIF is a rapid molecular diagnostic test that can simultaneously detect the presence of Mycobacterium tuberculosis (MTB) and resistance to the antibiotic rifampicin (RIF) in a single test. It is a key tool in the diagnosis and management of tuberculosis, a major respiratory tract infection.
Hemoptysis: Hemoptysis is the medical term for coughing up blood or blood-tinged sputum from the respiratory tract. It is a symptom that can indicate an underlying respiratory or cardiovascular condition, and it is an important consideration in the context of bacterial infections of the respiratory tract.
Lipoteichoic acid: Lipoteichoic acid (LTA) is a major component of the cell wall of Gram-positive bacteria. It is a glycolipid that anchors the teichoic acid polymers to the bacterial cell membrane, contributing to the structural integrity and function of the cell wall.
Bronchoalveolar Lavage: Bronchoalveolar lavage (BAL) is a diagnostic procedure in which a saline solution is instilled into the lungs and then suctioned out to collect a sample of cells and other material from the alveoli and lower respiratory tract. This procedure is used to assess and diagnose various respiratory conditions, including bacterial infections of the lungs.
M Protein: The M protein is a surface protein found on the cell wall of certain bacteria, particularly Streptococcus pyogenes, which is the causative agent of streptococcal infections such as strep throat. The M protein is a critical virulence factor that enables the bacteria to evade the host's immune system and establish successful infections in the respiratory tract.
Pleural Fluid: Pleural fluid is a thin, lubricating liquid found in the pleural space, the area between the lungs and the chest wall. This fluid helps reduce friction and facilitate the smooth movement of the lungs during breathing.
Respiratory Epithelium: The respiratory epithelium is the specialized lining of the respiratory tract, which includes the nasal passages, trachea, bronchi, and alveoli. This epithelium plays a crucial role in the normal function and defense mechanisms of the respiratory system.
Isoniazid: Isoniazid is a first-line antibiotic medication used in the treatment and prevention of tuberculosis (TB) infections. It is a key component of the standard multidrug regimen for TB and works by inhibiting the synthesis of mycolic acids, which are essential components of the Mycobacterium tuberculosis cell wall.
Polysaccharide Capsules: Polysaccharide capsules are a type of bacterial cell surface structure that consists of a thick, gelatinous layer of complex carbohydrates surrounding the cell wall. These capsules are important for bacterial infections of the respiratory tract as they help the bacteria evade the host's immune defenses.
Moraxella catarrhalis: Moraxella catarrhalis is a Gram-negative, aerobic, diplococcus bacterium that is commonly found as part of the normal microbiota of the human upper respiratory tract. It is an opportunistic pathogen that can cause various respiratory tract infections in certain populations.
Group A Streptococcus (Group A Strep): Group A Streptococcus, also known as Streptococcus pyogenes, is a gram-positive bacterium that is a common cause of respiratory tract infections. It is a leading cause of throat infections, such as strep throat, as well as more severe invasive infections.
Antibiotic Resistance: Antibiotic resistance is the ability of bacteria and other microorganisms to withstand the effects of antibiotics, rendering these drugs ineffective in treating infections. This phenomenon is a growing global health concern that has significant implications across various aspects of microbiology, including prokaryote habitats, antimicrobial discovery and chemotherapy, and the treatment of bacterial infections.
Tuberculosis: Tuberculosis (TB) is a serious infectious disease caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs, but can also spread to other parts of the body. TB is a major global health concern, with significant implications in the context of cell theory, gram-positive bacteria, antimicrobial discovery, public health, and respiratory tract infections.
Pili: Pili, also known as fimbriae, are hair-like appendages that protrude from the surface of many bacterial cells. These thin, filamentous structures serve various functions in prokaryotic cells, including attachment, motility, and communication, and are closely associated with the unique characteristics of prokaryotes, their habitats, relationships, and the virulence factors of eukaryotic pathogens, as well as bacterial infections in the respiratory tract, digestive system, and nervous system.
Biofilms: Biofilms are complex communities of microorganisms, primarily bacteria, that adhere to surfaces and are encased in a self-produced extracellular matrix. These microbial communities exhibit unique characteristics and behaviors that distinguish them from free-floating, planktonic microbes.