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Z - Micro 04
Micro 04
| Question | Answer |
|---|---|
| Most common cause of atypical pneumonia | Mycoplasma pneumoniae |
| Second most common cause of atypical pneumonia | Chlamydia pneumoniae |
| Newborn pneumonia | Chlamydia trachomatis |
| When treating for gonorrheal infection, what else should you also treat? | 50% of pts will be concurrently infected with both N. gonorrhea and Chl trachomatis so should empircally treat for both PLUS Ureaplasma urealyticum |
| Lactose fermenters | E.coli ferments, while Shigella and Salmonella do not |
| H2S production | Distinguishes between Shigella and Salmonella. Shigella does not, Salmonella does produce H2S. |
| EMB Agar | Methylene blue inhibits G+ bacteria; lactose fermenters = purple/black (enterics, NOT salmonella or shigella); E. coli = metallic green. |
| MacConkey agar | Bile salts inhibit G+ bacteria; lactose fermenters = pink/purple (enterics, E.coli, NOT salmonella or shigella) |
| H antigen | Flagella on bugs like E.coli and salmonella (not shigella) |
| Diarrhea with no cell invasion | E coli and V cholera; toxins in GI tract, but no inflammatory response |
| Diarrhea with GI EC invasion | EIEC, Shigella, Salmonella enteriditis; Bind and invade EC's --> release toxins inside EC's --> cells destroyed --> inflammatory response (fever) --> WBC's and RBC's in stool |
| Diarrhea with invasion of lymph nodes and bloodstream | Salmonella typhi, Yersinia enterocolitica, Campylobacter jejuni; Stool has WBC's and RBC's, systemic sx's (fever, headache, WBC elevation), lymph node enlargement, bacteremia |
| ETEC | Enterotoxigenic E coli. Heat Labile Toxin (LT), Heat Stabile Toxin (ST). Inhibit NaCl reabsorption; stimulate secretion of Cl and HCO3 --> water follows osmotic pull --> rice water diarrhea (like cholera, Campylobacter jejuni, and bacillus cereus, and Y |
| EHEC | Enterohemorrhagic E coli. Shiga-like toxin; inhibit 60S ribosomal unit --> inhibit protein synthesis --> EC death --> dead cells in stool and poor absorption --> diarrhea. Hemorrhagic colitis. |
| EIEC | Enteroinvasive E coli. Shiga-like toxin. Also invade EC's --> inflammatory response with WBC's and RBC's in stool |
| E coli 0157:H7 | EHEC in hamburger meat. Caused hemolytic uremic syndrome -- anemia, thrombocytopenia, renal failure. |
| red currant jelly sputum | Klebsiella pneumoniae |
| Yellow sputum | Staph aureus |
| UTI's in patients with Foley catheters | Klebsiella pneumoniae, Pseudomonas aeruginosa |
| Klebsiella pneumoniae pneumonia | Hospitalized pts and alcoholics |
| Motile and breaks down urea | Proteus mirabilis |
| Alkaline pH | Proteus mirabilis and Ureaplasma urealyticum - both split urea into NH3 and CO2 |
| Proteus antigens similar to which antigens? | Rickettsia |
| Produces bright red pigment | Serratia |
| Shigella | no flagella, does NOT ferment lactose (E coli does) or produce H2S (salmonella does) |
| Shigella dysentery strikes which populations? | Preshools and nursing homes. |
| Rose spots on belly | Typhoid fever - Salmonella typhi |
| Diagnosis of typhoid fever | Salmonella typhi found INSIDE monocytes (invades lymph nodes) |
| Mimics of appendicitis (RLQ pain) | Salmonella typhi (typhoid fever), Yersinia enterocolitica |
| Patients without spleens more susceptible to…. | Encapsulated bacteria: Salmonella, Haemophilus influenzae, |
| Those with sickle cell anemia prone to what type of infection? | Salmonella osteomyelitis (bone infection) |
| Food in fridge: can still get what? | Yersinia enterocolitica because it can grow in cold |
| Mechanism of cholera toxin | ADP ribosylation of GTP binding unit --> inc cAMP --> secretion of NaCl --> osmotic pull of water and electrolytes into GI tract |
| Mechanism of Shiga toxin | inactivate 60S ribosomal unit of intestinal EC's --> kills ECs --> dead EC's in stool --> poor absorption --> diarrhea |
| Burn victims | 1. Staph aureus, 2. Pseudomonas aeruginosa |
| wound dressings that smell like grape and look blue/green | P. aeruginosa, blue pigment - pyocyanin |
| CF patients | lungs infected with P. aeruginosa. Normally, P cleared by binding to CFTR channel. No CFTR channel in these patients, so no clearance. |
| Diabetic patients with foot ulcers | susceptible to osteomyelitis from P aeruginosa |
| IV drug users | Osteomyelitis from Pseudomonas aeruginosa in clavicle or vertebrae; R heart valve endocarditis from Pseudomonas aeruginosa and Staph aureus. |
| Contact lens wearers | Corneal infection from Pseudomonas aeruginosa |
| Which G- bacteria has no endotoxin? | Bacterioides fragilis (abscesses) |
| Periodontal disease, black pigment on blood agar | Bacterioides melaninogenicus |
| What does Haemophilus influenzae require for growth | Blood: X factor (Hematin), V factor (NAD+) |
| Ddx for painful genital ulcer | 1. Syphilis, 2. Herpes, 3. Chlamydia infxn. |
| What is difference between chancroid and syphilis? | Chancroid = Haemophilus ducreyi, painful ulcer, painful unilateral lymph node, pus. Syphilis/SyphiLESS = Treponema pallidum, painLESS ulcer, painLESS BILATERAL LN, no pus |
| What is difference between chancroid and herpes? | Chancroid = Haemophilus ducreyi, painful ulcer, painful unilateral lymph node, no systemic sx's. Herpes = Herpes simplex virus 1 and 2, start as blisters that pop (looks like ulcer), painful, Systemic sx's like myalgias and fevers |
| What is difference between chancroid and chlamydial infxn (lymphogranuloma venerum)? | Chancroid = Haemophilus ducreyi, painful ulcer, painful unilateral lymph node, at the same time. LGV = Chlamydia trachomatis, primary ulcer disappears before PAINLESS LNs enlarge. |
| female patient with pruritis of the labia, dysuria (burning on urination), fishy-smelling discharge | Gardnerella vaginalis - bacterial vaginitis |
| How to confirm bacterial vaginitis? | Clue cells: gardnerella vaginalis (G- pleomorphic bacilli) in EC cytoplasm |