Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
32 Cards in this Set
- Front
- Back
|
What are the characteristics of Pseudomonas aeruginosa?
|
gram-negative, aerobic however considered by many to be facultative anaerobe, rod-shaped, unipolar motility
opportunistic grape-like or tortilla-like odor |
|
|
What is the most important cell-surface polysaccharide in regards to P. aeruginosa?
|
Lipopolysaccharide
plays a key structural role in outer membrane integritiy as well as being an important mediator of host-pathogen interactions |
|
|
What is the pathogenesis of P. aeruginosa?
|
it is an opportunistic, nosocomial pathogen of immunocompromised individuals, typically infects the pulmonary tract, urinary tract, burns, wounds, and also causes other blood infections. SKIN INFECTIONS, Otitis EXTERNA
|
|
|
What is the virulence factor for P. aeruginosa?
|
virulence factor exotoxin A to ADP-ribosylate eukaryotic elongation factor 2 in the host cells much as the diphtheria toxin does.
without factor 2, eukarytoic cells cannot synthesize proteins and necorse |
|
|
What is the defense mechanism behind anitibiotic resistance of P. aeruginosa?
|
modification of a porin
|
|
|
What are a few antibiotics that have activity against P. aeruginosa?
|
aminoglycosides (gentamicin, amikacin, tobramycin) quinolones (ciprofloxacin, levofloxacin, and moxifloxacin); cephalosporins, polymyxins
|
|
|
What are the mechanisms of resistance that is used by P. aeuroginosa?
|
The low susceptibility is attributable to a concentrated action of multidrug efflux pumps with chromosomally-encoded antibiotic resistance genes and low permeability of the bacterial cellular envelops
acquired resistance either by mutation in chromosomally-encoded genes or by horizontal gene transfer of antibiotic resistance determinants |
|
|
What are the characteristics of Enterobacter cloacae?
|
gram-negative, facultatively-anaerobic, rod-shaped bacterium, peritrichous flagella
oxidase negative and catalase positive opportunistic bacteria |
|
|
What is fungal ecology?
|
distribution:fungi are everywhere
Energy source: ALL heterotrophs Soil: major source |
|
|
What is the basics of fungal structure?
|
molds: grow as filaments; septate hyphae, aseptate hyphae, reproduce by spores
yeasts: single-cell growth, reproduce by budding Dimorphism:mold (soil), yeast (tissue) |
|
|
What are the basics of a fungal cell wall?
|
multi-layered, polysaccharide subunits (mannans, glucans, chitin, protein fibrils)
|
|
|
What type of mycotic disease is Histoplasmosis?
|
it is a dimorphic fungi (grows as intracellular yeast in macrophages and mold in environment)
Histoplasma capsulatum |
|
|
Where is Histoplasmosis most prevalent?
|
Endemic in Mississippi and Ohio River valleys
(grows in bird poo, but does not infect them); does not infect cattle or birds |
|
|
How are canines usually infected with Histoplasmosis and what does it casuse?
|
inhalation of microconidia
respiratory disease, tends to disseminate to GI tract, can visualize intracellular yeast in tissue |
|
|
What is the pathology assoicated with Histoplasmosis?
|
tends to form granulomatous lesions, small intracellular yeast in macrophages, can have small miliary lesions
|
|
|
What is the fungus that causes Blastomycosis?
|
Blastomyces dermatitidis
|
|
|
Where is Blastomycosis typically found (distribution)?
|
moist soil
Wisconsin is endemic area- also Kentucky and Tennessee |
|
|
What is the pathogenesis of Blastomycosis?
|
inhaled-moist organic soild, hyperendemic areas; transforms into yeast, resistant to killing, respiratory disease can be mild or inapparent, disseminates to skin, eyes, and causes intense local inflammation
|
|
|
What is the pathology of Blastomycosis?
|
pyogranulomatous
broad-based budding yeast surrounded by inflammatory cells- PMN's |
|
|
What is the general pathogenesis of fungal diseases?
|
Systemic mycoses: virulent dimorphic pathogens (deep mycoses), opportunistic infections
Subcutaneous mycoses: sporotrichosis, mycetoma and others Cutaneous mycoses: Dermatophytes "Ringworm", Mycotoxicodes- ingestion of toxins |
|
|
What is the pathogen that causes coccidioidomycosis?
|
Coccidioides immitis which is endemic in southwestern US, San Juaquin Valley-- "Valley Fever"; Phoenix--"desert fever", MOST VIRULENT FUNGAL PATHOGEN
|
|
|
What are the fungal characteristics of coccidioidomycosis?
|
Dimorphic
hyphae, arthospores in sandy soil spherules, endospores in tissue |
|
|
What is the pathogenesis of coccidioidomycosis?
|
causes an initial pulmonary infection- disseminates to long bones (legs) and elsewhere
arthrospores inhaled, germinate into spherules in lung, spherules cleave internally into endospores granulomatous inflammation (macrophages, lymphocytes) can disseminate via lymphatic and bloodstream to other sites |
|
|
What is the etiologic agent of cryptococcosis?
|
encapsulated yeast Cryptococcus neoformans
cuases insidious meningitis, sometimes skin lesions (esp. in cats) |
|
|
What is the distribution and ecology of cryptococcosis?
|
found worldwide, not restricted to endemic areas; prefers to grow in pigeon droopings, which are high in creatinine, does not infect pigeons, dries out over time, loses capsule, easier to inhale
|
|
|
What is the disease sings seen in dogs and cats infected with cryptococcosis?
|
infection thought to usually initiate in the lung, disseminates to other sites, including CNS, skin and eyes
cats: perhaps secondary inoculation of skin? Horses: meningitis Cattle: mastitis |
|
|
What is the pathogenesis of cryptococcosis?
|
Thoguht that dessicated yeast are inhaled: innate defenses usually adequate, if large exposure, or weak CMI, infection progresses, capsular polysaccharide-forms in vivo
infection disseminates to CNS: develops slowly, few inflammatory cells in CSF, difficult to visualize yeast |
|
|
What is the virulence mechanisms and host defense of cryptococcosis?
|
capsule inhibits phagocytosis
capsular polysaccharide-induces T suppressor cells melainin-increases resistance to ROI anti-capsular Ab response- usually weak Ab will opsonize, increase killing by neutrophils and macrophages |
|
|
What are some common dermatophytes that cause dermatophytosis?
|
causes infections of keratinized epithelium: Microsporum, Trichophyton, and Epidermophyton
|
|
|
What is the pathogenesis of dermatophytosis?
|
incubation-enter hair follicules
spread- grow downward along hair shafts, invade zone of keratinization, arthrospores form as hairshaft grows upward, refractory period-hairs break, hyphae lost; involution: hairs return to normal; reinfection or recrudescence |
|
|
What is the host response to Dermatophytosis?
|
lesions can be very inflammatory, more severe inflammation, more likely that organism will be cleared
lots of inflammaotry cells (PMNs) exudate-lactoferrin etc. evidence of both humoral and cellular immune response |
|
|
What are the bacterial characteristics of Staphlyococcus intermedius?
|
gram-positive, round (cocci), form grape-like clusters
normally found on the skin and mm |
