Microbiology GAME TIME Respiratory C. Diptheriae: look for less than 5yrs of age, pseudomembrane, gram positive bacilli, and it has a toxoid vaccine for prevention. Bronchiolitis in adults can mimic pertussis or TB in adults. TB: what do you need to overcome the infection? Cell-mediated immunity. Legionairres – anytime you see air-conditioners or humidifiers. CMV – two cases you will see this is if newborn has pneumonia (acquired from mother) or immunosuppression (owl-eye cells). Chest X-ray: If you see median to lateral interstitial infiltration and always unilateral, its mycoplasma pneumonia (to diagnose, you use cold agglutinin test, b/c these antibodies precipitate at 4 degrees celcius). If you see interstitial infiltration ALWAYS bilateral, its usually aspiration pneumonia caused by RSV. If you see median to lateral with bi-fissure, that’s Klebsiella. If you see lateral to median with patchy infiltration, its Aspergillosis (cavity will already have been present). If you see opaque, dense, and its hard to differentiate bronchial trees, its mycobacterium tuberculosis (TB will show lower lobe to upper lobe) Know differences between: typical vs. atypical and nosocomial vs. community acquired. Know age groups, manifestations, and etiological agents for both things. Ex. Strep pneumoniae in lobar pneumonia will be in lower lobe, and will not reach upper lobe, but in atypical, it will spread to different parts. Know the first two organisms that cause each. Nosocomial pneumonia – you’ll see it in a case where person renal failure, abdominal surgery, head trauma, or any underlying lung disease; and then 40 hours later you’ll have the infection. Difference between viral vs. bacterial: In bacterial, cytokines are released along with fluid accumulation, and in viral, there is no fluid production. Diagnose b/w pneumonia and bronchitis/bronciolitis: Pneumonia will have production cough, initial fever may not be present, chest x-ray will not show opacities. Bronchitis will show dry cough with fever and chills and chest x-ray will show opaque bronchial tree. Cavities: TB or aspergilosis – know the structure for diagnosis. Aspergilosis – branching, septate hyphae with vesicle. Diff b/w bronchitis in healthy patient and one with underlying lung disease: Healthy patient – persists for a few days. Underlying lung disease patient – will persist for a long time, need to treat very fast, can lead to pneumonia. Do most cases of tracheobronchitis resolve on their own or are antibiotics usually required? Treat with broad spectrum antibiotics b/c if you don’t it can lead to pneumonia. The tracheobronchitis is an airway infection, so it can be treated easily b/c it is not attached to pharyngeal wall or has not gone deep into the lungs. If you have an organism, you need to know if its toxin mediated or enzyme mediated; and you need to know the gram stain and culture and how that looks. Pneumonia: H. influenza – No growth on blood agar, growth on chocolate agar (b/c of the X and V factors), pleiomorphic, and gram negative bacilli. Strep. Pneumoniae – capsular swelling (process is negative staining) will be positive. Chlamydia – gram stain (no bacteria), culture will be negative, cell culture will show intracytoplasmic inculsion bodies. H. influenza is more common than Strep. Pneumonia in causing bronchitis. H. Influenza: Know the two glycoprotein spikes (hemagglutinin and neuraminidase) which are on the outside. Inside is where you see RNP. Antigenic drift – frequent change in antigenic structure that causes epidemics. Antigenic shift – there will be a change in the antigenic structure that will last for a long time (pandemic causing). Know the vaccines (Hib). (slide 29 in Pneumonia) Know the different ways invaders avoid normal defense mechanisms. Pharyngitis: Why is important to distinguish Strep pharyngitis from other forms of the disease? 90% of pharyngitis cases are viral, so complications after treatment are much more severe (Ex. Rhematic Fever, glomerulonephritis). Aspergillosis: It is a type of chronic pneumonia. The manifestations happen over a period of 1 to 2 months. (Last case in Pneumonia slide show – slide 140) – This is a case of aspiration pneumonia caused by Stenotrophomonas. What do you do? You give antibiotics for GI infection. Stenotrophomonas is GI infection that lodges into the lungs, hence why it is aspiration. Common causes for aspiration pneumonias are GI enterobacteria. GI Tract Why are anti-emetics and anti-diarrheal not given to children? B/c in the case of dysentery it will complicate conditions. In dysentery and EHEC, they are invasive; so you need to give anti-biotics. Hep A is considered GI infection because it is feco-oral transmission; whereas B and C are serum hepatitis spread through blood transfusions. For infections of teeth (dental caries), the organism is Strep mutans. Generalized Manifestations: Know the difference b/w diarrhea and dysentery based what you see in microscopy. Peptic ulcers: H. pylori – comma shaped, most potent for urease test. Camp. Jejuni – also comma shaped, but will be negative urease. Also know the type of ulcer each of these two bacteria causes to distinguish. Duodenal ulcers – Giardiasis. Gasteroenteritis: Bacterial: for all these, know the morphology, culture, and manifestations. EHEC – Shigella – blood and mucous stools. Salmonella – incubation time is 6-48 hours. Ex. Case will say that “16 hours ago, so ate some shit, so now she’s fucked up”. Camp. Jejuni – urease negative and bloody diarrhea with ulcers. Viral: Rotovirus – small children, 0 to 2 years. Food-borne infections: Staph. aureus, Salmonella, E. Coli. For all three of these, know the incubation times and food materials that you find them in. Bac. Cereus – Chinese fried rice. Vibrio parahemolyticus – shell fish/oysters. Foor-borne Hepatitis: Hep A and Hep E are feco-oral and are the ones that will be in the food. For Hep A, B, and C, know the graph and what serological markers to look for. A – feco-oral transmission, its not a virus, and its considered GI. Blood-borne Hepatitis: B, C, D. Know the structure of the virus, transmission, graphs, serological markers, vaccinations, and know that D will not be without B. (Ex. Case where patient was infected with B ten years prior, and now has symptoms; he prolly has D). Eye Infections Conjunctivitis: Bacterial: Chlamydia is the number one cause, H. ducreyi is the second cause. Viral: Adenovirus is number one, and other causes are due to secondary infections. Onchocerca volvulus: this is also called “River blindness”; it is a parasitic eye infection. Ecanthameoba: it is a protozoal parasite; the one that chills in the contact lens. There are things called tric agents (Trachoma Inclusion conjunctivitis). They have different serotypes (look up). Zoonotics Brucellosis: know the morphology, culture, manifestations; this is also called Undulant Fever. Anthrax: look at slides and know manifestations; also called Woolsorters Disease. Q Fever: know manifestations, diagnosis. Leptosporiasis: morphology, manifestations, and diagnosis. SDL Topics One question on each of these topics; student presentations will suffice: Otitis Parotitis Aspergillosis Cystic Fibrosis Vibrio parahemolyticus Giardiasis Pseudomembranous colitis Levinson Questions are needed to be looked at. Especially the “All are true except …. “ Extra Notes: Cryptosporiodosis (parasite) – this is a GI infection that happens in immunocrompromised patients. T. soleum – causes cysticercosis. Know incubation times for Staph, Salmonella, Bacillus cereus, Camp jejuni, and Vibrio genus. Hep: know what happens at what stage on the diagnostic graphs. Ex. This patient was treated for HepB five years ago (so it is a chronic case), what markers will you see? HBe antigen.
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