Step 1 - Micro 3

denniskwinn's version from 2015-04-25 16:09


Question Answer
Anthraxgram+ spore forming rod. 2. Produces anthrax toxin 3. Cutaneous anthrax- contact - black eschar - can progress to bacteremia and death. 4. Pulm anthrax - inhalation of spores - flulike rapidly progress to fever, pulm hemorrhage, mediastinitis and shock
Black skin lesionsblack eschar (necrosis) surrounded by edematous ring - caused by lethal factor and edema factor of anthrax
Woolsorter’s diseaseinhalation of spores from contaminated wool
Produces a unique capsule containing D-Glutamate
Question Answer
Listeria monocytogenesintracellular (facultative) 2. Acquired by ingestion of unpasteurized milk/cheese and deli meats or by vaginal transmission during birth. 3. Forms actin rockets to move cell to cell 4. Only gram + with endotoxin - characteristic tumbling motility
Listeria can cause1. Amnionitis, septicemia, spotnaneous abortion 2. Granulomatous infantiseptica, neonatal meningitis, meningitis in immunocompromised pts, mild gastroenteritis in healthy individuals
Actinomyces vs. Nocardia1. Gram + rods forming long branching filaments resembling fungi 2. Actinomyces causes oral/facial abscesses that may drain through sinus tracts in skin 3. Nocardia causes pulm infection in immunocompromised pts 4. Sulfa for Nocardia, Penicillin for Actinomyces
Actinomyces israeli and txgram + anaerobe 2. Oral/facial abscesses that may drain through sinus tracts in skin 3. Normal oral flora 4. Treat with penicillin
Nocardia asteroides and txgram + and also weakly acid-fast aerobe in soil 2. Causes pulm infection in immunocompromised pts 3. Treat with sulfa
PPD+with current infection, past exposure or BCG vaccination
PPD-no infection or anergic (steroids, malnutrition, immunocompromise, sarcoidosis)
Primary TB infectioninfection with TB in nonimmune host (usually child) - Ghon complex (hilar nodes and lower lobes) or ghon focus (lower lobes alone)
Primary TB progression1. Heal by fibrosis - get immunity and hypersensitivity 2. Progressive lung disease (HIV malnutrition) can to death 3. Severe bacteremia - miliary tb -to death 4. Preallergic lymphatic or hematogenous dissemination→dormant tubercle bacilli inseveral organs →reactivation in adult life
Secondary TBpartially immune hypersenitized host gets reinfection
Extrapulmonary TB1. CNS (parenchymal tuberculoma or meningitis) 2. Vertebral body TB (Pott’s disease) 3. Lymphadenitis, Renal, GI - 4. Can occur from reactivation in adult life
Ghon complexTB granulomas with lobar and perihilar LN involvement - reflects primary infection or exposure
m. TuberculosisTB, often resistant to multiple drugs
m. Kanasiipulm TB-like
TB symptomsfever, night sweats, weight loss, hemoptysis
Avium-intracelluareoften resistant to multiple drugs: causes disseminated disease in aids.
Hansen’s disease (Leprosy)caused by M. Leprae - an acid fast bacillus that likes cool temperatures. 2. Two forms - lepromatous and tuberculoid 3. Lepromatous presents diffusely over skin and is communicable (failed CMI) 4. Tuberculoid is limited to a few hypoesthetic nodules 5. Resevoir in US = armadillos 6. Infects skin and superficial nerves
Hansen’s disease treatment Long term oral dapsone (toxicity is hemolysis and methemoglobinemia) - Alternate tx = rifampin and combination clofazimine and dapsone
Lactose fermenting enteric bacteriagrow pink colonies in MacConkeys = Citrobacter, Klebsiella, E. Coli, Enterobacter, Serratia
Penicillin and gram - bugsGram - bacilli are resistant to benxypenicillin G but may be susceptible to penicillin derivatives (ampicillin) - gram - outer membrane blocks penicillin G and vancomycin
Gonococci1. N. Gono 2. Ferment glucose only 3. No polysaccharide capsule, 4. No vaccine (rapid antigenic variation) 5. Sexually transmitted, 6. Causes gonorrhea, septic arthritis, neonatal conjunctivitis, PID
Meningococci1. N. Meningitidis 2. Ferment glucose and maltose 3. Polysaccharide capsule 4. Vaccine 5. Spread via Resp and oral secretions 6. Causes meningococcemia and meningitis, waterhouse-Friderichsen syndrome
H . Flu1. Epiglottitis (cherry red in kids), Meningitis, Otitis media and Pneumonia 2. Small gram - rod 3. Aerosol transmission 4. Most invasive disease is cause by capsular type B 5. Produces IgA protease 5. Culture on chocolate agar requires factors V and X 6. Does not cause the flu
Haemophilus influenzae txTreat meningitis with ceftriaxone, Rifampin prophylaxis in close contacts
Legionella pneumophila1. Legionnaires’ disease and Pontiac fever 2. Gram - rod (use silver stain) 3. Grow on charcoal yeast w/iron and cysteine. 4. Detected clinically by antigen in urine 5. Aerosol transmission from water source - no person to person transmission 6. Treat with erythromycin
Legionnaire’s disease sxsevere pneumonia and fever
Pontiac fever sxmild flulike syndrome
Pseudomonas aeruginosa associationsPub hosed - Pneumo (esp in CF), UTI, Burns and wounds, Hottub, Osteomyelitls, Sepsis (black skin lesions), External otitis (swimmer’s ear, malignant in diabetics),Drug use and Diabetic
Pseudomonas aeruginosaAerobic gram - rod, Non-lactose fermenting, oxidase +, Produces pyocyanin (blue-green pigment), grape-like odor,. Water source, produces endotoxin and exotoxinA(inactivates EF-2)
Pseudomonas aeuruginosa treatmentaminoglycodside plus extended-spectrum penicillin (Piperacillin, ticarcillin)
EnterobacteriaceaeE.coli, Salmonella, Shigella, Klebsiella, Enterobacter, Serratia, Proteus 2. Have somatic O antigen (polysaccharide of endotoxin) 3. Capsular (K) antigen related to virulence of bug 4. Flagellar (II) antigen found in motile species 5. Ferment glucose and are oxidase negative
EIEC1. Invades intestinal mucosa 2. Shiga-like toxin 3. Associated with Dysentary (microbe invades and toxin causes necrosis and inflammation)
EHEC1. Does not invade intestinal mucosa 2. Shiga-like toxin 3. Assoc w/ dysentary (toxin alone causes necrosis and inflammation)
ETEC1. Does not invade intestinal mucosa 2. Labile toxin/stable toxin 3. Assoc w/traveler’s diarrhea
EPEC1. Does not invade intestinal mucoas 2. No toxin produced - adheres to apical surface - flattens villi, prevents absorption 3. Diarrhea (usually in children)
Klebsiellaintestinal flora that causes pneumonia in alcoholics and diabetics when aspirated 2. Red currant jelly sputum 3. Also causes nosocomial UTIs - 4 As (aspiration pneumonia, Abscesses in lungs, Alcoholics, di-A-betics)
Salmonella vs. Shigella1. Both - non-lactose fermenters - both invade intestinal musoca and can causes blood diarrhea 2. Salmonella have flagella and can disseminate hematogenously and produce H2S 3. Salmonella sx may be prolonged w/antibiotic tx 4. Shigella more virulent than salmonella 5. Salmonella have animal resevoir 6. Shigella do not have flagella but can propel themselves while within a cell by actin polymerization 7. Transmission - food, fingers, feces, flies
Salmonella typhicauses typhoid fever - fever, diarrhea, headache, rose spots on abdomen - can remain in gallbladder chronically
Yersinia enterocoliticaUsually transmitted from pet feces (e.g. Puppies), contaminated milk, or pork. Outbreaks are common in day-care centers. Can mimic Crohn’s or appendicitis, especially in adolescents
H.pylori1. Causes gastritis and up to 90% of duodenal ulcers. 2. Risk for peptic ulcer, gastric adenocarcinoma and lymphoma. 3. Gram - rod 4. Urease + 5. Creates alkaline environment 6. Treat with triple therapy: 1. Metronidazole, bismuth and either tetracycline or amoxicillin. Or - metronidazole, omeprazole, clarithomycin
Spirochetes1. spiral shaped bacteria with axial filaments 2. Borrelia (big size), Leptospiria, Treponema 3. Borrelia - can be visualized using aniline dyes 4. Treponema visualized by dark-field microscopy
Leptospira interrogans1. Question mark-shaped bacteria found in water contaminated with animal urine 2. Flulike sx, fever, headache, abdominal pain, jaundice and photophobia with conjunctivitis. 3. Most prevalent in the tropics. 4. Causes weil’s disease = ictohemorrhagic leptospirosis
Weil’s disease1. Ictohemorrhagic leptospirosis (spirochete) 2. Severe form with jaundice and azotemia from liver and kidney dysfunction, fever, hemorrhage and anemia
Lyme disease1. Borrelia burgdorferi 2. Transmitted by tick Ixode 3. Presents with erythema chronicum migrans (expanding bull’s eyes) 4. Joints, CNS, heart
Lyme disease treatmentdoxycycline, ceftriaxone
3 stages of lyme disease1. Erythema chronicum migricans, flulike sx 2. Neurologic (bell’s palsy), Cardiac (AV nodal block) 3. Chronic monoarthritis and migratory polyarthritis
Treponemal disease1. Spirochetes 2. Pallidum causes syphillus, 3. Pertenue causes yaws; infection of skin, bone and joints→healing with keloids→severe limb deformities. Disease of tropics, not an STD but VDRI+
Primary syphilisPainless chancre
Secondary syphilisDisseminated disease with constitutional sx, maculopapular rash (palms and soles), condylomata lata.
Tertiary syphilisGummas (chronic granulomas) , aortitis (vasa vasorum destruction) , neurosyphilis (tabes dorsalis), Argyll robertson pupil - broad based ataxia, positive romberg, charcot joints, stroke without htn
Congenital syphilisSaber shins, saddle nose, CNVIII deafness, Hutchinson teeth, mulberry molars
Argyll robertson pupilconstricts with accomodation but is not reactive to light - assoc w/tertiary syphillis
VDRLtest for syphilis - positive in active infection and good chance of false positive
FTA-ABSspecific for treponemes, turns positive earliest in disease and remains positive longest. Most specific, earliest positive, remains positive longest
VDRL false positivesdetects nonspecific antibody that reacts with beef cardiolipin. Used to diagnose syphilis but many biologic fp including viral infection (mono, hep), some drugs, rheumatic fever, SLE, leprosy