True or false. Atypical pneumonia is caused by a pathgogen other than Streptococcus pneumoniae or can be considered a primary pnemonia that did not involve an initiating viral infection.
A 76 year-old male presents to your office with complaints of coughing up purulent sputum, feelings of "tightness" in the chest and having difficulty breathing. X-rays confirm fluid build-up in the lungs. You have the patient to give you a sputum sample and exam it under a microscope. You find PMNs and gram+ lancet-shaped diplococci. What is the diagnosis and what is the pathogen that is most likely involved?
C. Pneumonia; Streptococcus pneumoniae (most common causative agent for pneumonia in the elderly)
A 27 year-old HIV patient comes into your office complaining of malaise, a terrible cough with productive purulent sputum, feelings of "suffocation", and tightness in their chest. You ask the patient to give you a sputum sample which, when cultured, grows on blood agar, is alpha-hemolytic, is susceptible to Optochin and is bile soluble. What is the diagnosis and what pathogen is most likely involved?
B. Pneumonia; Streptococcus pneumoniae (commonly seen in young, HIV patients)
What virulence factors are involved in the evasion of the immune system and tissue damage in lower respiratory tract infections caused by Streptococcus pneumoniae?
A man brings his 2-year old son into your office with concerns that the young boy might have the flu. The father tells you that his son has been lethargic and has been coughing up nasty "green" stuff. He goes on to tell you that he doesn't believe that his son has been vaccinated because his wife has a fear of them and thinks that they cause Autism. You collect a sputum sample from the boy and exam it under a microscope. You find small, gram- coccobacillary rods. You culture the sample and find that the organisms only grow on chocolate agar with the presence of X and V factors. This confirms your diagnosis. What is the diagnosis and what pathogen is most likely involved?
B. Haemophilus influenzae
A 4-year old presents in your office with acute epiglottis and pneumonia. You take a swab of the epiglottis and exam it under a microscope. You find small, gram- coccibacillary organisms with a polysaccharide capsule. What is the diagnosis and most likely pathogen involved?
D. Atypical pneumonia; Haemophilus influenzae
A 55-year old man with a history of smoking and heavy alcohol use, comes into your office and presents with pneumonia-like symptoms. He tells you that the symptoms began shortly after taking a trip to Chicago where he and his family went fishing out on Lake Michigan and even jumped in for a quick swim. You ask him to give you a sputum sample to test under a microscope but no organisms are found. As a last resort you aspirate his lungs. Upon examination of the tissue specimen you find organisms multiplying inside phagocytes and "coiling phagocytosis". What organims are the likely cause of this man's infection?
C. Legionella pneumophila
What 2 syndromes are caused by Legionella pneumophila?
True or false. Legionella pneumophila does not gram stain well and requires amino acids, L-cysteine and ferric ions to grow in media.
What 3 organisms are gram- and are coccobacillary-shaped?
What 2 pathogens cause "walking pneumonia"?
An 18-year old college student who just started school a few weeks ago and lives in a dormitory, comes into your office presenting with acute atypical pneumonia. You collect a sputum sample for examination, but it fails to show any organisms. You then attempt to culture the sputum, but the organisms are taking too long to grow. Finally, you perform a serodiagnostic test and detect circulating antibodies to a particular pathogen. Which pathogen is it?
C. Mycoplasma pneumoniae
A 10-year girl is brought into your office by her mother who says her daughter claims she hasn't been feeling well and seems to have pneumonia-like symptoms, but has not had to miss school. You suspect that she may have a "walking pneumonia" caused by Chlamydia pneumonia, because it is very common in schoolchildren and young adults. To confirm the diagnosis, which of the following would be the best way to clinically identify the causative agent?
What are the 3 most common lower respiratory tract infections caused by Staphylococcus aureus? How would you clinically ID this organism in the lab?
Sputum, lung abscess aspirate, or blood culture are positive for gram+ cocci in clusters and the organisms are catalase and coagulase positive
What are the 2 most important virulence factors involved in lower respiratory tract infections caused by Mycobacterium tuberculosis?
disseminated TB - infection of liver, spleen,kidney, bone, meninges
reactivation TB -
Which skin test is used for the detection of TB?
DTH test - reaction to purified protein derivative (PPD)
What response is involved in TB infection?
cell-mediated immunity response
A 43-year old woman comes into your office presenting with significant muscle wasting and fever. She complains of a chronic productive cough with bloody sputum. You collect a sputum sample to view under a microscope. You gram stain the sample. It appears to be gram-, but it's difficult to tell because it stains poorly. An acid-fast bacillus stain appears to be more successful. Upon further examination, there are no spores present. You want to confirm you diagnosis with a culture, but the organisms are growing too slowly. Instead, you take an X-ray of the patient's chest and find a tubercle granuloma in her right lung. What is the diagnosis and the pathogen most likely responsible for the infection?
A. Mycobacterium tuberculosis
A woman brings her 15-year son, who is a cystic fibrosis patient, into your office. She is concerned that her son's condition is worsening. The last antibiotics that were prescribed for him were uneffective. She goes on to tell you that he had recently been diagnosed with a Staphylococcus aureus infection a few months ago. Soon after this infection, her son developed cystic fibrosis. You take a sample of the boy's sputum to exam it under a microscope. You find gram- rods. What is the most likely pathogen involved?
C. Pseudomonas aeruginosa (primary infection of S. aureus puts young patients at an increased risk for developing cystic fibrosis caused by pseudomonas aeruginosa)
A sputum sample from a cystic fibrosis patient has been cultured. Gram- rods grow under aerobic conditions, have a greenish-blue pigment and are oxidase+. What is the most likely organism?
C. Pseudomonas aeruginosa
What 6 organisms (that we've learned about thus far) are oxidase+?
What are the most important virulence factors involved in Pseudomonas aeruginosa infection of the lower respiratory tract?
adhesins - binds to asialGM1
alginate and elastase - tissue damage
exotoxin A - ADP-ribosylation of elongation factor 2 (similar to diptheria toxin)
A cancer patient who has been in the hospital for the last week, presents with chronic bronchitis. You take an X-ray of the patient's chest and see a "fungus ball" in their pulmonary cavity. Alarmed by the findings, you decide to aspirate one of the lungs to confirm the diagnosis. Upon examination of the aspirate you find septate hyphae with conidia. There does not appear to be any dimorphic forms. What pathogen is most likely involved in this infection?
D. Aspergillus spp.
Which 3 fungi have dimorphic growth phases? (think: H.B.I.C.!)
A few days ago, a 27-year old man returned from a trip to the Mississippi River Valleys with his family. During his visit, he did a lot of hiking through soil and other terrain. He is now experiencing pneumonia-like symptoms and comes to see you in your office. You take a sample of his sputum to test for presence of organisms, but there are none. You then decide to take an X-ray of his chest. It shows a granuloma. To confirm the diagnosis you take a blood sample and culture it on a Sabouraud agar plate. You tell the patient that you will follow up with him, because it could take a few weeks to get the results of the culture growth. In the meantime, you examine some of the blood sample under a microscope to find tuberculate macroconidia in dimorphic growth phases. The diagnosis has been confirmed. Your patient is infected with what pathogen?
A. Histoplasma capsulatum
What serologic test can be used to ID Histoplasma capsulatum?
DTH skin test
What is the most important virulence factor involved in Histoplasma capsulatum infection of the lower respiratory tract?
ability to grow inside of macrophages and survice oxidative bursts
True or false. Blastomyces dermatitidis has the capicity to grow inside of macrophages, similar to Histoplasma capsulatum.
False, Blastomyces dermatitidis is extracellular.
A patient has developed necrosis and fibrosis of their right arm and it is becoming disfiguring. They report having visited Florida over the weekend. You take a biopsy of the lesion and exam it under a microscope. Large yeast cells with broad buds are visible. What is the most likely pathogen involved?
C. Blastomyces dermtitidis
True or false. Blastomyces dermatitidis and Coccidioides immitis are too "big" to be taken up by macrophages.
What is the invasive form of Coccidioides immitis?
A 23-year old female has just returned from a family visit to Arizona a few days ago. She comes into your office complaining of cough, chest pain and myalgia. You take a biopsy of her lungs and examine a histological section. It is highly populated with spherules. Some have even burst and are releasing endospores. Lastly, you perform a skin test on her and she has a DTH reaction to antigens of a particular organism. What is the mystery pathogen?
D. Coccidioides immitis
True or false. The inflammatory response to C. immitis infection is accompanied by granuloma formation.
An AIDS patient comes into your office with a CD count of 150 cells/mm^3 and presents with pneumonia-like symptoms. You take an X-ray of their chest and find lesions outside of the lungs. The alveoli are also filled with desquamated cells, organisms, monocytes and fluid. They have a "foamy appearance". There are also diffuse alveolar infiltrates visible on the X-ray. A sputum sample is not useful in identifying organisms, so you take a biopsy of the lung tissue and stain it using Giemsa. Cysts and trophs become visible. What is the most likely pathogen involved?
B. Pneumocystis jirovecii (PCP)
If an AIDS patient presents with a low grade fever, a nonproductive cough, shortness of breath, a rapid breathing rate, has blue skin or decreased oxygen, what is the most likely diagnosis based on these symptoms?