Bacterial Diseases of the Respiratory System
|Upper respiratory system|| 1) Diphtheria|
2) Streptococcal pharyngitis (strep throat)
3) Scarlet fever (not really upper respiratory but is a complication of strep throat which ends up in the respiratory system)
|Lower respiratory system|| 1) Pertussis (whooping cough)|
4) Atypical (walking) pneumonia
5) Legionella (Legionnaire's disease
|Diphtheria||-caused by Corynebacterium diphtheria|
-Gram positive, classified as a baccilus but it's really pleomorphic rod
-The bacterium must be infected with a virus to produe the toxin that causes the symptoms of the disease. Transmission is by cough produced droplets and fomites.
-Symptoms - slight fever, fatigue, sore throat, (very characteristic examples are next) bull neck and formation of psuedo membrane which is a thick grayish/white membrane over the soft pallet and tonsils
- the above symptoms are if the disease is treated quickly if not treated quickly it can cause death from the toxin by progressive organ failure
- Diagnosis based on symptoms of bull neck, treat quickly or death due to progressive organ failure caused by toxin will occur.
- Controlled by antibiotics, i.e. penicillin, cephalosporins, and antitoxin which is produced in horses
Prevent by immunizing. DPT vaccine - diphtheria, pertussis, tetnus
|Lysogenic conversion||is when a situational virus infects bacteria and provides some genetic information to make a toxin and the toxin causes symptoms of disease|
|Streptococcal pharyngitis (strep throat) - caused by Gram + coccus Streptococcus pyogenes||Gram positive coccus AKA group A Beta hemolitic strep|
-Group A pertains to having a marker molecule on cell for identifying purposes
-Beta hemolitic pertains to Beta hemolosis
-Transmitted by inhalation of respiratory secretions or possible organisms could be normal flora but not probable
-Symptoms - sore throat, swollen tonsils (maybe), swollen lympth nodes, fever. Middle ear infection is a common complication.
-Diagnosis- classic way is to swab back of the throat and look for evidence of beta-hemolysis or another way is the "instant strep test" (there are a # of these instant tests) process is the same, you have to swab the back of the throat for testing
-Treatment - penicillin is the drug of choice, some drug resistance is seen with this drug, erythromyacin is the 2nd choice, but NOT tetracycline due to bug resistance. There are 55 types of this bug!
-A common problem with Strep is middle ear infection AKA otitis media
|Scarlet fever - caused by Streptococcus pyogenes||-This is a complication of strep throat|
- a viral infected strain of Streptococcus pyogenes, these strains produce an Erythrogenic (red causing) toxin
-Transmission - inhalation of respiratory secretions
-Symptoms are typically red skin rash, due to an allergic reaction to toxin, high fever, tongue becomes spotted and swollen, a week later the red skin rash will peel, deafness is a possible complication.
-Treatment - penicillin, erythromyacin (same as strep throat)
|Pertussis (whooping cough) - caused by bordetella pertussis||Gram negative coccobacillus|
-Transmission - inhalation respiratory secretions, coughs, highly contagious, usually seen in unimmunized infants < 1 year old
-incubation 10 days
-Symptoms - mild cough, sneezing, inflamed throat at this point the upper symptoms - next 10-14days go to the lower system then severe cough (trouble inhaling) vomiting, sometimes the violence of the cough will crack ribs, lasts 2-3 weeks
-Treatment - erythromyacin, ampicillin, tetracycline, Immunize!! DPT vaccine
-patient will have partial immunity upon recovery of disease but if they do get it again it will be milder
|Tuberculosis - caused by Mycobacterium tuberculosis||Gram positive acid fast bacillus|
-Transmission - 75% of cases by inhalation of airborne droplets but you can get it from skin or GI tract
-historically this disease is associated with poverty, over crowding and now with AIDS
-incubation 2-6 weeks then we get into primary infection - microphages engulf bacteria then they actively multiply inside of the microphages, microphages move all over the body. at this point no symptoms are seen or mild flu like symptoms
-Primary infection by 2-6 weeks later infection a hypersensitive response occurs = allergic response - tuberbcles form at the sites of bacillarymulitiplication. in the lungs can be seen at this time - these tubercles become separated by us building walls around them and then the walls become calcified and then they are inactived because they are surrounded by calcified walls but if the patient is not healthy to start with then they will experience the following symptoms - necrosis of lung tissue, chronic fever, weight loss, night sweats, persistant cough which is blood tinged, at this point not uncommon to spread to other organs
-Diagnosis - PPD (purified protein derivative, Chest X-ray, Acid-fast stain sputum sample
-Vaccine - BCG vaccine (bacilli Calmette Guerin) not used in US
-Treatment - highly drug resistent organism - treatment will last 6-9 months to 2 years, they will be given
-adult tb is more common in men over 50 years of age classic with alcholism, malnutrition, and diabetics and almost always occur in lungs
-a coctail of drugs will be used - hard core drugs make the patient feel crappy - we can't really afford to hospitalize so we rely on the patient to continue taking the meds and they don't take it for the entire time so they get drug resistant (drugs used are Isoniazin, rifampin, ethambutol and others)
Reactivation (adult) tuberculosis - occurs most often in men after the age of 50. often associated with malnutrition, alcoholism, diabetes, and stress. occurs most often in lungs. lesions spread and necrosis of the tissue occurs.
Symptoms - chronic fever, weight loss, night sweats, cough
Active cases demonstrated by acid fast rods in sputum
T.B. test - intradermal injection of protein from M. tuberculosis called PPD (purified protein derivative)
(+) tst due to delayed hypersensitive response - Red, hardened area in 48-72 hours.
It indictes an active case, previous infection or the individual has been immunized against TB. Confirm with an acid-fast stain, chest xray or biopsy
BCG Vaccine (Bacille Calmette Guerin) used in Europe to prevent childhood cases of TB
Treatment - double or triple therapy for 6-9 months to help prevent development of resistant strains
Isoniazid, rifampin and others
|Pneumonia caused by Streptococcus pneumoniae||Gram positive coccus|
70% of bacterial pneumonias are caused by this bug. It may be normal flora of the upper respiratory tract, an immunocompromised host is the ideal candidate for this disease.
-vaccine Pneumococcal polysaccharide vaccine given to elderly and high risk patients
-transmission - possilby/likely normal flora in upper respiratory
-symptoms-fever, adema of lungs, fluid produced in lungs, which makes gas exchange difficult
-70% of cases will have spontaneous recovery in 5-7days if treatment is required then penicillin or erythramyacin will be used
|Atypical (walking pneumonia - caused by Mycoplasma pneumoniae (a bacterium with no cell wall)||lacks a cell wall so not gram positive or negative|
- slow grower
-incubation 2-3 weeks, ages most common 5-15 years old, found in close social groups like daycare
-inhalation or normal flora is not common
-symptoms fever, cough, edema of lungs, often self limiting (you recover without treatment) no immunity
-treatment - tetracycline, erythramyacin
|Pneumonia caused by Klebsiella pneumoniae|| Gram negative rod with a capsule.|
-transmission is normal flora, 5-10% of people are normal, common in nature ie soil, water, and on plants
-causes other things surgical wound infection, UTI's
-symptoms - same
-Diagnosis based on symptoms
-treatment - a million different
|Legionella (Legionnaire's disease) - caused by Legionella pneumophila||Gram negative rods. 1st isolated by CDC in 1/77. it was difficult to figure out what had caused the mysterious disease outbreak that occurred at the leionnaires convention that year becuase this bug cant be cultivated on microbiological media. it must be grown in an anmimal. they used guinea pigs. the bug is actually common in aquatic ecosystems.|
transmission - it was spread by a contaminated air conditioning system.
symptoms - 10 days after exposure - muscle and headache, high fever, cough, chest and abdominal pain, diarrhea and shortness of breath.
if untreated 15-30% of the infected die from pneumonia followed by shock. acute pneumonia is the most common pathology.
treatment - hospitilization is required, recovery in 1-2 weeks with erythromycin.