英文ppt课件bacterialand viral

Bacterial and Viral Infections -Pulmonary Pathology Lab 1- Robert Allan, MD Bacterial and Viral Infections Lab Case based exercises to reinforce concepts of lecture Group work is encouraged Case #1 55 year old male with a past medical history of hypertension presents with a one week history of cough with green sputum, fever and malaise. He smokes 1 pack a day and has so for 20 years. A chest x-ray shows an infiltrate in the left lower lobe. What is the most likely diagnosis? - PNEUMONIA Case #1- Smoker with pulmonary infiltrate and fever What category of pneumonia does this most likely fall into? - COMMUNITY ACQUIRED ACUTE PNEUMONIA What are the most likely organisms responsible? Streptococcus pneumoniae Haemophilus influenzae Moraxella catarrhalis Staphylococcus aureus Case #1 Healthy male with pulmonary infiltrate and fever What host condition may have contributed to the development of this and how? - Smoking. This leads to the impairment of the mucociliary apparatus which helps to clear organisms from the lungs What should be done next to determine therapy? - Culture of blood, sputum and/or bronchoalveolar lavage fluid. Case # 2 24 year old female college student with no significant past medical history presents with a two week history of malaise, minimal cough, body aches. Some of her friends have been sick with similar symptoms. What general category does this presentation most likely fit into? - COMMUNITY ACQUIRED ATYPICAL PNEUMONIA. Case #2- College student with malaise Name three organisms that may cause this ? -Mycoplasma pneumonia -Chlamydia pneumonia -Viral pneumonia (influenza or other viruses) Case # 3 67 year old with hypertension, coronary artery disease, chronic obstructive pulmonary disease (COPD) presents with a four-day history of marked fatigue, increased shortness of breath, and body aches. She does not report a fever. She is concerned because she was going to go on a Winter cruise in two weeks time. She states that last year she got some shots for “something” but this year she didnt get any because it “kinda hurt”. She does not smoke. What diagnoses are you considering in this patient? -PNEUMONIA. -Congestive heart failure (CHF) may also give you shortness of breath and fatigue, not typically body aches but this could also be excluded (for example measuring BNP) Case #3- 67 year old with malaise, SOB Does the absence of fever exclude any diagnoses under consideration? - No. Both bacterial and viral pneumonias may have an absence of fever so this should not limit the differential diagnosis. This paradoxical absence of fever may be seen in the very old. What should be done next? -Chest x-ray -Gram stain, Culture of the sputum, laboratory studies to rule out viral infection Case #3- 67 year old with malaise, SOB The chest x-ray shows scattered bilateral homogeneous opacities- the radiologist favors that this represents an atypical or viral pneumonia. A rapid test enzyme-linked immunosorbent assay (ELISA) for influenza virus on nasal secretions is positive, bacterial cultures do not grow pathogenic organisms A diagnosis of influenza is made, supportive care is provided Case # 4 The 67 year old woman from Case# 3 returns to clinic five days later with complaints of fever, shortness of breath and thick sputum that is red-brown in color. She states that she was feeling better and then the symptoms “changed” and she felt much worse. What should you be concerned about? - Secondary bacterial pneumonia occurring after Influenza virus pneumonia Case # 4- The 67 year old returns List mechanisms that contribute to the development of secondary bacterial pneumonias following viral infections (how does it impair the host defenses)? - Viral infection damages the mucociliary escalator, impairs the production of mucus thus weakening host defenses. Case #4- The 67 year old returns The sputum was sent for culture which grew out a bacterial organism, a gram stain of this culture is shown above, what is the result, what is the most likely organism? -Gram positive cocci in clusters, Staphylococcus aureus Case #4- The 67 year old returns What does the gram stain show below? -Gram positive cocci in pairs and short chains If this sputum gram stain was from a patient with community acquired acute pneumonia, what is the most likely organism? -Streptococcus pneumoniae Case #4- The 67 year old returns Regarding Staph aureus and Strep pneumoniae: -Which is/are gram positive? -Staphylococcus aureus and Strep pneumoniae are both gram positive - Which occurs in clusters? -Staphylococcus aureus - Which organism has a thick polysaccharide capsule? -Streptococcus pneumoniae - Which organism has a vaccine available for high risk individuals? -Streptococcus pneumoniae - Name two groups that are considered high risk for Strep. pneumoniae? -Elderly and those without a spleen (remember asplenia is a risk for infection with encapsulated organisms) Case # 5 A 55 year old male presents with a very high fever (102 F) of seven days duration, slight cough, feeling woozy and “out of it”. A chest x-ray showed bilateral infiltrates- the radiologist says it is not specific for any organism but consistent with pneumonia. Sputum gram stain did not reveal any infectious organisms. The patient has seen his family doctor three days ago who gave him a cephalosporin antibiotic but he has not been feeling any better. In this patient with community acquired acute pneumonia what should you be concerned about? -Viral pneumonia, bacterial pneumonia including unusual organisms and secondary bacterial pneumonia -The severity of the presentation would be unusual for the atypical pneumonias Case # 5- High fever, pneumonia You obtain additional history. None of his family or close contacts have been sick. He works as a haberdasher (tailor). He has not had any unusual exposures. He reports that two weekends ago he was working in his garden installing a water fountain that draws water from a creek behind his house. He adds that he used the fountain as a mister to keep him cool. Now what should you be concerned about? -Legionella pneumonia -The diagnosis was established by a urine antigen test (tests for the presence of a protein from Legionella that is excreted in the urine). Legionella characteristically causes a high fever and mental status changes. It does not respond to antibiotics typically used to treat community pneumonia such as cephalosporins or penicillins because it is an intracellular organisms (FYI I will not test on treatments) Case # 6- Cough with sputum A 58 year old male with history of smoking, COPD presents with shortness of breath, cough, thick sputum and low grade fever. A chest x-ray was preformed which is shown. The radiologist says that there are multiple patchy opacities. Right lung with multiple opacities Case # 6- Cough with sputum A virtual lung lobectomy is performed (this does not exist but I needed to somehow incorporate gross images without killing him off) and the lung tissue looks like: - What pattern of pneumonia does the radiographic and pathologic features best fit? -Bronchopneumonia Case # 6- Cough with sputum Histologic sections of the virtual lobectomy show the following: - What pattern of pneumonia does the pathologic features best fit? -Bronchopneumonia. This one is a little bit tricky. The structure in the middle of the image is an airway. Note the inflammatory cell infiltrate is largely centered around the airway with minimal involvement of the surrounding alveoli. Case # 6- Cough with sputum Higher magnification of the virtual lobectomy shows the following: - What is the predominant cell type within the infiltrate? -These are neutrophils. Remember they are also called polymorphonuclear leukocytes. They typically have multiple lobated nuclei. They are involved in processes characterized by acute inflammation such as pneumonias. Case # 7 A 65 year old male presents with fever, cough, shortness of breath, malaise and sputum production. He is previously healthy with a remote history of smoking. A chest x-ray was preformed with the following result: What does the chest x-ray show? -Dense consolidation in the right middle lobe Case # 7- 65 year old with dense consolidation A virtual autopsy was performed (again I didnt want to knock the patient off) and the right middle lobe of the lung is shown. Compared to the more normal appearing lung (at top), this area is firm to palpation. What is the pattern of pneumonia? -Lobar pneumonia involving the right middle lobe Case # 7- 65 year old with dense consolidation Virtual histologic sections from the right middle lobe are shown (inset is higher magnification) What is the pattern of pneumonia? -Acute lobar pneumonia the alveoli are filled with neutrophils Case # 8 A 10 month old has increased difficulty in feeding and becomes increasingly fussy. Initially the symptoms consisted of runny nose and nasal congestion but after five days the child develops cough, dyspnea and wheezing. There is a low grade fever. The child was the product of a term pregnancy and has received scheduled vaccinations including the HIB (Hemophilius influenza B vaccine). What does the chest x-ray show? -Bilateral fine infiltrates Case # 8- Baby got cough A virtual tissue biopsy was performed on the lung. The result is shown below. What is the most likely diagnosis? Respiratory syncytial virus (RSV)- the #1 cause of bronchiolitis and pneumonia in children under 1. A rapid ELISA based test that utilizes a nasopharyngeal swab is available and widely used to diagnose RSV. Case #8- Baby got cough What time of year is does this particular organism tend to strike? -Winter A friend of the childs family tells them that they saw on Oprah that after you get this infection, the child will be protected from getting it again. Is this true, would Oprah ever lie? -No. You can get re-infected with RSV again though the symptoms are generally milder the second time around (probably develop partial immunity) Case # 9 A 48 year old who appears malnourished presents with high fever, cough, sputum and a dense infiltrates and a cavitary lesion (cystic space with air-fluid level) on chest x-ray. When asked when this started he says that he doesnt remember. He states that he drinks a few beers on the weekends. He lives in a homeless shelter. Outside of the room a companion of the patient tells you that he drinks hard liquor “all the time” and that recently he was found passed out on the street outside of the shelter. What do you think the chest x-ray findings mean? - The presence of dense consolidation of the lung indicates pneumonia. The cavitary lesion with an air-fluid level means that there is an fluid filled abscess cavity in the lung. Case # 9- Drinker with pneumonia What is/are the primary risk factors for the development of pneumonia in this patient? - Heavy drinking and malnutrition How do these contribute to the development of pneumonia? - Alcohol consumption alters the mental status and may impair the swallow reflex along with a loss of consciousness which may allow the aspiration of oral bacteria Case # 10 A 46 year old with a history of intravenous drug use and multiple unprotected sexual partners pre