Chp 22 Diseases of the Respiratory Tract

Streptococcal pharyngitis (Strep throat) and Scarlet fever
Symptoms/Diagnosis: Fever, pain, swollen tonsils, pustules and a “beefy” red appearance. Scarlet fever produces high fever and a red rash on the upper body. Isolates from throat cultures positive for
B-hemolytic streptococci.
Streptococcal pharyngitis (Strep throat) and Scarlet fever
Causative agent/Contributing factors: Streptococcus pyogenes may infect the pharynx or tonsils. Untreated infections may lead to rheumatic fever and glomerulonephritis.
Streptococcal pharyngitis (Strep throat) and Scarlet fever
Transmitted by direct and indirect contact, droplets, and fomites.

Prevention/Treatment: Penicillin and erythromycin

Diptheria
Symptoms/Diagnosis: Disease is characterized by sore throat, fever, malaise, and swelling of the neck. Blockage of the patients airway may occur due to a leather-like membrane that forms in the throat. Diptherial exotoxin causes interruption of protein synthesis leading to organ failure. The exotoxin is primarily responsible for the debilitating effects of the disease. Diagnosed by immunodiffusion tesing (Elek test).
Diptheria
Causative agent/Contributing factors: Corynebacterium diptheriae is the causative agent of disease. This bacterium often colonizes individuals who then become carriers.
Diptheria
Transmission is by respiratory route (droplets and fomites).

Prevention/Treatment: Vaccination with diptheria toxoid confers immunity (DPT shot). Erythromycin or penicillin are the drugs of choice for active cases.

Acute coryza (Common cold)
Symptoms/Diagnosis: Nasal and sinus congestion, runny nose, sore throat, coughing. Recovery time is from one to two weeks. Fever usually not seen. Complications include sinusitis, laryngitis, otitis media and bronchitis (especially in children).
Acute coryza (Common cold)
Causative agent/Contributing factors: Many types of viruses may cause colds (Rhinoviruses and Coronaviruses). This is why no specific vaccine has ever been produced. Colds are more prevalent during winter months probably due to increased time spent indoors. People over 60 yrs of age average about 1 cold/year while children average 3-4 colds/year. Transmission is thought to be primarily through indirect contact.
Acute coryza (Common cold)
Transmission: Self-inoculation with virus in droplets from suroundings.

Prevention/Treatment: Frequent hand washing can prevent colds. No specific cure available. Rest and hydration speeds recovery. Analgesics and antihistamines may relieve symptoms.

Bacterial pneumonias
Symptoms/Diagnosis: Fluid accumulation in the lungs, fever, chest pain, abnormal chest sounds and impairment of respiratory function, are indicative of bacterial pneumonia. Bacterial pneumonia frequently leads to fatal complications in hospitalized patients. Diagnosed by sputm cultures, symptoms, and serological testin. Incubation- days to weeks
Bacterial pneumonias
Causative agent/Contributing factors: There are 5 principle causative agents of bacterial pneumonias, these are: Streptococcus pneumoniae, Klebsiella pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila, Chlamydia psittaci.
Bacterial pneumonias
Transmission: Most of these pathogens are opportunistic, they may overgrow from normal flora, some transmitted by infected animals (birds), others found in building ventilation equipment.

Prevention/Treatment: Intensive therapy with the appropriate drug: Vancomycin for staph and strep, tetracycline for Chlamydia and Mycoplasma. Cephalosporins for Klebsiella and Hemophilus

Tuberculosis (Consumption)
Symptoms/Diagnosis: A chronic progressive infection of the lungs. Symptoms include: weight loss, coughing, rust-colored sputum, chest pains, malaise, night sweats. In advanced stages blood is coughed up and caseation is seen. “Tubercles” are seen on chest x-ray. Tuberculosis may invade the rest of the body (lymph, bones, brain). Screening and diagnosis is done by a variety of tests: tuberculin skin tests (PPD), Mantoux test, chest x-rays, acid-fast stain, and/or culture of microbe on Lowenstein-Jensen agar.
Tuberculosis (Consumption)
Causative agent/Contributing factors: Mycobacterium tuberculosis is the causative agent of the disease.
Tuberculosis (Consumption)
Transmission: droplets, aerosols and fomites. Contributing factors include smoking, old age, poor nutrition, overcrowded/unsanitary living conditions, substance abuse (alcoholism), diabetes and immunosupression (HIV)

Prevention/Treatment: Patients diagnosed with tuberculosis must undergo a strict regiment of long term antibiotic treatment. Drugs administered include: Isoniazid, ethambutol, rifampin, pyrazinamide, ciprofloxacin, and streptomycin. Drugs are often given in combination since resistant strains have been reported. Medicated patients are rendered non-contagious.

Pertussis (Whooping cough)
Symptoms/Diagnosis: Initially resembles a cold (runny nose, fever) then progresses to the paroxysmal stage where violent coughing is produced. This is due to bacterial toxins destroying the ciliary escalator in the trachea of the infected person. Sudden inhalation after coughing produces the characteristic “whooping” sound associated with the disease. Complications can be severe: tissue destruction, ruptured diaphragm, broken ribs, ruptured blood vessels. Incubation 6-20 days.
Pertussis (Whoppong cough)
Causative agent/Contributing factors: Bordetella pertussis is the causative agent.

Transmitted by inhalation of droplets or aerosols produced by an infected individual

Prevention/Treatment: An acellular pertussis vaccine is given to infants. Antibiotics can be given to destroy bacteria

Inhalational Anthrax
Symptoms/Diagnosis: Flu-like symptoms:sore throat, muscle aches, cough and malaise. Incubation is rapid (1-5 days). The infection may rapidly progress to respiratory distress, shock and death. Diagnosed by culturing bacterium, serological and DNA testing.
Inhalational Anthrax
Causative agent: Endospores of Bacillus anthracis

Transmission: via inhalation of spores present in dust, animal hides, or dispersed deliberately. 8,000-50,000 inhaled spores constitutes an infectious dose. Inhalational anthrax is non-communicable from person to person

Prevention/Treatment: Rapid and sustain administration of antibiotics such as ciprofloxacin, penicillin, erythromycin. Vaccine available but usually only given to military personnel.

Influenza
Symptoms/Diagnosis: Headaches, chills, fever, muscle aches. Influenza infections may lead to life-threatening complications in elderly patients (bronchitis, pneumonia). Incubation 7-10 days
Influenza
Causative agent/Contributing factors: The influenza virus is the causative agent of the flu. This is a RNA virus which may undergo antigenic shift. The virus may also infect horses, pigs, geese, ducks, chickens, and various bird species. New antigenic strains emerge yearly from china.
Influenza
Transmission: Aerosols, droplets from infected humans and animals. Self-inoculation of virus from surroundings.

Prevention/Treatment: Influenza vaccines must be given yearly to prevent disease. Epidemiological monitoring data is used to decide which vaccine should be produced. Medications may be administered to reduce the severity and duration of this disease: amantadine, rimantadine, oseltamivir, zanamivir

Severe Acute Respiratory Syndrome (SARS)
Symptoms/Diagnosis: high fever, headaches, body aches, coughing, pneumonia.

Causative agent/Contributing factors: SARS associated Coronavirus. 2-7 days for incubation.

Severe Acute Respiratory Syndrome (SARS)
Transmission: Droplets from infected individuals.

Prevention/Treatment: Limit travel during outbreaks, frequent hand-washing. Steroids and interferon therapy for infected individuals.

Respiratory Syncytial Virus (RSV)
Symptoms/Diagnosis: Typical symptoms of pneumonia (fever, wheezing, respiratory distress etc.). Fused cells (syncytia) are seen in sputum samples of infected individuals. Viral pneumonia can result in tracheobronchitis (croup)
Respiratory Syncytial Virus (RSV)
Causative agent/Contributing factors: in infants respiratory syncytial virus (paramyxovirus) is the most common cause (RSV). Especially prevalent in children under the age of 1 year. Common in late winter months. 4-6 days.

Transmission: Droplets and fomites from infected individuals.

Prevention/Treatment: Aerosol administration of ribavrin. Prevented by monoclonal vaccine (Synagis)

Hantavirus pneumonia
Symptoms/Diagnosis: acute onset pneumonia with high fever, chest pains, respiratory distress, hemorrhages, and high fatality rates. 14-30 days.

Causative Agent/Contributing factor: Hantavirus found in rodent droppings.

Hantavirus pneumonia
Transmission: infection occurs from accidental inhilation of dust or particles from rodent droppings.

Prevention/Treatment: careful decontamination of areas showing rodent feces. Chlorine bleach solution should be used prior to feces removal to kill viruses and minimize dust or aerosols. Infected patient will require hospitalization and intensive supportive care.

Histoplasmosis
Symptoms/Diagnosis: Poorly defined, but may resemble the onset of tuberculosis. Histoplasmosis is frequently seen among immunosuppressed individuals.
Histoplasmosis
Causative agent/Contributing factors: Histoplasma capsulatum, a dimorphic yeast.

Transmission: Inhalation of fungal spores found in soil and bird/bat droppings.

Prevention/Treatment: Itraconazole, amphotericin-B, or ketoconazole.

Pneumocystis pneumonia
Symptoms/Diagnosis: an opportunistic pneumonia often an indicator disease of the AIDS syndrome. Once rare, this disease is a major cause of mortality in the immunosuppressed population
Pneumocystis pneumonia
Causative agent/Contributing factor: Pneumocystis jirovecii an opportunistic fungus, which is part of the normal flora, is the cause of this disease.

Transmission: Inhalation of droplets containing fungus, overgrowth of pathogen in immunosuppressed individuals.

Prevention/Treatment: Trimethoprim-sulfamethoxazole

Categories: Microbiology