Bacterial Diseases

Acute otitis media (AOM)Haemophilus influenzaeStreptococcus pneumoniaeMoraxella catarrhalis, othersEarache, possible effusion; may cause fever, nausea, vomiting, diarrheaOften a secondary infection; bacteria from respiratory tract become trapped in eustachian tube, cause infection
DiphtheriaCorynebacterium diphtheria (gram +)Pseudomembrane on throat, possibly leading to suffocation and deathInhalation of respiratory droplets or aerosols from infected person
Legionnaires diseaseLegionella pneumophila(gram )Cough, fever, muscle aches, headaches, nausea, vomiting, confusion; sometimes fatalInhalation of aerosols from contaminated water reservoirs
Pertussis (whooping cough)Bordetella pertussis(gram )Severe coughing with “whoop” sound; chronic cough lasting several months; can be fatal in infantsInhalation of respiratory droplets from infected person
Q feverCoxiella burnetiiHigh fever, coughing, pneumonia, malaise; in chronic cases, potentially fatal endocarditisInhalation of aerosols of urine, feces, milk, or amniotic fluid of infected cattle, sheep, goats
URI/Streptococcal pharyngitis, scarlet feverStreptococcus pyogenes(gram +)Fever, sore throat, inflammation of pharynx and tonsils (mucosal membranes of the pharynx are damaged by the release of a variety of exoenzymes and exotoxins by this pathogen), petechiae, swollen lymph nodes; skin rash (scarlet fever), strawberry tongueDirect contact, inhalation of respiratory droplets or aerosols from infected person
TuberculosisMycobacterium tuberculosis(acid-fast, high G + C, gram+, nonspore-forming rod)Formation of tubercles in lungs; rupture of tubercles, leading to chronic, bloody cough; healed tubercles (Ghon complexes) visible in radiographs; can be fatalInhalation of respiratory droplets or aerosols from infected person
Diseases of Respiratory Track caused by Bacteria


Acute otitis media is an infection of the middle ear, caused by several bacteria, including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. The infection can block the eustachian tubes, leading to otitis media with effusion.

Bacterial pneumonia results from infections that cause inflammation and fluid accumulation in the alveoli,  caused by S. pneumoniae or H. influenzae.

Mycoplasma pneumonia results from infection by Mycoplasma pneumoniae

Chlamydial pneumonia can be caused by three pathogens that are obligate intracellular parasites. Chlamydophila pneumoniae is typically transmitted from an infected person, whereas C. psittaci is typically transmitted from an infected bird. Chlamydia trachomatis, may cause pneumonia in infants.

Tuberculosis infection leads to the production of protective tubercles in the alveoli and calcified Ghon complexes that can harbor the bacteria for a long time.

In Tuerculosis, bacteria infects the alveolis & phagocytized by macrophages.  but M. tuberculosis can survive and multiply within these phagocytes due to presence of the waxy mycolic acid in their cell walls which protect them &  not eliminated by macrophages. the infection result into an inflammatory response and an accumulation of neutrophils and macrophages in the infected area of alveloi. In the alveoli  small round lesions called tubercles. Bacteria continue to be grow into the the tubercles and results in tissue damage and induction of apoptosis (programmed host-cell death) in a process called liquefaction. This creates air pocket, where the aerobic M. tuberculosis can grow and multiply. Tubercles may eventually rupture and bacterial cells can invade pulmonary capillaries; from there, bacteria can spread through the bloodstream to other organs, a condition known as miliary tuberculosis. The rupture of tubercles also facilitates transmission of the bacteria to other individuals via droplet aerosols that exit the body in coughs.

Eventually, most lesions heal to form calcified Ghon complexes. These structures are visible on chest radiographs and are a useful diagnostic feature. But even after the disease has apparently ended, viable bacteria remain sequestered in these locations. Release of these organisms at a later time can produce reactivation tuberculosis or secondary TB.

Q fever is caused by Coxiella burnetii bacteria, whose primary hosts are domesticated mammals (zoonotic disease).

Sequelae of S. pyogenes Infections (aggressively treated with antibiotics), Leads to acute rheumatic fever and acute glomerulonephritis.

Rheumatic fever is damage to and inflammation of the heart (carditis)Glomerulonephritis: an immune response to streptococcal antigens following pharyngitis and cutaneous infections.

Health Care-Associated Pneumonia: Klebsiella pneumoniae, Staphylococcus aureus

A pertussis infection :three distinct stages. The initial infection catarrhal stage, is relatively mild and unremarkable. The signs and symptoms may include nasal congestion, a runny nose, sneezing, and a low-grade fever. This stage is most infectious. Sec stage, paroxysmal stage, mucus accumulation leads to uncontrollable coughing spasms that can last for several minutes; whooping sound made is made during the paroxysmal stage. The paroxysmal stage can last for several weeks. A long 3rd stage convalescence stage, during which time patients experience a chronic cough that can last for up to several months.


PNEUMONIA:- Itis a term for infections of the lungs that lead to inflammation and accumulation of fluids and WBC in the alveoli. Pneumonia can be caused by bacteria, viruses, fungi, and other organisms, but most of the majority of pneumonias are bacterial in origin.

DiseasePathogenSigns and SymptomsTransmission
Chlamydial pneumoniaChlamydophila pneumoniaeC. psittaciChlamydia trachomatisBronchitis; mild to severe respiratory distressInhalation of respiratory droplets or aerosols from infected person (C. pneumoniae); exposure to infected bird (C. psittaci); exposure in the birth canal (Chlamydia trachomatis)
Haemophilus pneumoniaHaemophilus influenza(gram )Cough, fever or low body temperature, chills, chest pain, headache, fatigueInhalation of respiratory droplets or aerosols from infected person or asymptomatic carrier
Klebsiella pneumoniaKlebsiella pneumoniae, othersLung necrosis, “currant jelly” sputum; often fatalHealth care associated; bacteria introduced via contaminated ventilators, intubation, or other medical equipment
Mycoplasma pneumonia (walking pneumonia)Mycoplasma pneumoniaeLow fever, persistent coughInhalation of respiratory droplets or aerosols from infected person
Pneumococcal pneumoniaStreptococcus pneumoniae(gram +)Productive cough, bloody sputum, fever, chills, chest pain, respiratory distressDirect contact with respiratory secretions
Pseudomonas pneumoniaPseudomonas aeruginosaViscous fluid and chronic inflammation of lungs; often fatalHealth care associated; bacteria introduced via contaminated ventilators; also frequently affects patients with cystic fibrosis
Bacterial Diseases

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