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116 Cards in this Set
- Front
- Back
Obligate aerobes
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absolute requirement of oxygen to grow
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Obligate anaerobes
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grow only under conditions of high reducing intensity, oxygen is toxic
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Facultative anaerobes
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Grow under aerobic or anaerobic conditions
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Microaerophilic organisms
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Grow best under low oxygen intensity, high oxygen may be inhibitory
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Aerotolerant aerobes
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Can tolerate oxygen but do not use it metabolically
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Spore-forming, gram-positive, anaerobic bacilli
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Clostridium spp.
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Strict anaerobes die within _____ of oxygen exposure
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10 minutes
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Enzymes that protect against toxic effects of oxygen production
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catalase, superoxide dismutase and peroxidase
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Catalase
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breaks down hydrogen peroxide to water and oxygen, aerobic or facultative bacteria
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Peroxidase
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breaks down hydrogen peroxide to water and oxygen, aerotolerant anaerobes
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Phase 1 of anaerobe sensitivity to oxygen
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electrons used in metabolic processes diverted to reduction of molecular oxygen, bacteriostatic, reversible
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Phase 2 of anaerobe sensitivity to oxygen
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Killed by toxic substances (superoxide anion, hydrogen peroxide, hydroxyl radical) that accumulate during reduction of molecular oxygen, irreversible
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_________ can be added to anaerobic transport media to maintain a reduced environment
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Reducing agents like thioglycolate and L-cysteine
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________ is more important than maintaining a reduced environment when growing anaerobic organisms
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Excluding oxygen
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Most anaerobes that cause infection are also normal flora (T/F)
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True
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In the body, most environments hospitable to anaerobes have _______ present because _______.
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organisms capable of respiration, these organisms maintain an environment of little oxygen and low redox potential
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Most anaerobic infections are seen in abcesses and necrotizing tissues (T/F)
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True
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Brucella blood agar
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nonselective, used for isolation of any anaerobe, supplemented with vitamin K and hemin
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Bacteroides bile esculin agar
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Selective for presumptive ID of B. fragilis
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Phenylethyl alcohol sheep blood agar
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inhibits nonanaerobic gram-negative bacilli which might otherwise overgrow anaerobes
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Culture observations indicative of presence of anaerboes
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Foul odor, good growth on BBA plate, colonies on anaerobically incubated BBA plate but not on CO2 incubated SBA or CBA plate
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Anaerobic gram-negative non-spore forming bacilli are usually normal flora (T/F)
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True, sites include oropharynx, lower GI, vagina, cervix, urethra and external genitalia
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Bacteroides is the most frequently isolated gram-negative anaerobe in humans (T/F)
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True
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Is Bacteroides motile or nonmotile?
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Nonmotile
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What antibiotics does B. fragilis have resistance to?
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Kanamycin, colistin, vancomycin
It is also bile resistant (up to 20%) |
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Prevotella is usually isolated from _______
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the oral cavity, head/neck, lower respiratory and urogenital tracts
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What color pigment does Prevotella display on BBA and LKV?
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brown-black
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What color does Prevotella fluoresce under UV light on BBA or LKV?
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brick red
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Porphyromonas ferments which sugars?
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None, it is asaccharolytic
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Fusobacterium is what shape under the microscope?
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Fusiform with tapered ends. Long and spindle shaped.
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Colony morphology of Fusobacterium nucleatum
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Small, slightly convex colonies with ground-glass appearance
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Peptostreptococcus is considered normal flora on skin (T/F)
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True, it is also normal flora in the upper respiratory tract, intestinal and genitourinary tract
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Peptostreptococcus causes _______
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abcesses and necrotizing soft tissue infections
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Veilonella is involved in development of ______
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early periodontal disease as well as meningitis, endocarditis and osteomyelitis
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Veilonella morphology under microscope
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tiny, gram-negative diplococci
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Mobiluncus is motile or non-motile?
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motile
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Mobiluncus has what morphology under the microscope?
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gull-wing or curved rod
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Mobiluncus causes what illness?
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Vaginosis, usually associated with Gardnerella vaginalis
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Propionibacterium acnes is rarely a contaminant in blood cultures (T/F)
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False, this organism is a very common contaminant of anaerobic blood cultures
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Actinomycosis
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"Lumpy jaw"
characterized by painful abcesses in mouth, lungs or GI tract Purulent drainage from sinus cavities contains "sulfur granules" |
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Clostridium perfringens microscopic morphology
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Large, boxcar shaped rods, sometimes stain gram negative (even though they are gram positive)
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Infections associated with C. perfringens
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gas gangrene, septicemia, gangrenous cholecystitis, anaerobic pulmonary infection, food poisoning
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Gas gangrene (myonecrosis)
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Rapid invasion and liquefactive necrosis of the muscle with gas formation and symptoms of toxicity
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Food poisoning due to Clostridum perfringens is self-limiting (T/F)
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True, it is caused by an enterotoxin
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Clostridium difficile has a _______ appearance on CCFA
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yellow, ground-glass appearance
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CCFA
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cycloserine-cefoxitine-egg-fructose agar
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Clostridium difficile has what odor?
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Horse-stable
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Necrotizing bowel disease may be caused by ______
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Clostridium difficile
rarely, C. ramosum, C. septicum |
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_______ causes pseudomembranous colitis
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Clostridium difficile
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C. difficile produces ______, which causes _______ and _______ which causes _______ effects
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toxin A, fluid accumulation
toxin B, cytopathogenic |
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Botulism is ________
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a life-threatening neuroparalytic disease caused by the preformed heat-labile toxins of C. botulinum characterized by a descending paralysis
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Infant botulism is caused by ingesting ______ and causes _______
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spores, constipation followed by descending paralysis
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Tetanus is caused by _______
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a toxin released by C. tetani
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Tetanus is a _______ paralysis
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spastic
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The toxin released by C. tetani is _______. This toxin works by _______.
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tetanospasmin, blocking inhibitory impulses.
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Best samples for Clostridium
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tissue biopsy or aspiration, fecal specimens for C. dificile or C. botulinum
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Prereduced anaerobically sterilized media
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Anaerobic blood agar, Laked kanamycin-vancomycin blood agar, phenylethyl alcohol agar, Bacteroides bile esculin agar
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Anaerobic primary media should not be exposed to oxygen for _____
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48 hours
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Bacteroides urealyticus will grow in 20% bile (T/F)
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False, of the Bacteroides species, only B. fragilis will grow in 20% bile
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Fusobacterium is sensitive to _______
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kanamycin and colistin
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Veilonella is resistant to ______
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vancomycin
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If an anaerobic gram-positive cocci is resistant to metronidazole, it is probably _________
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anaerobic Streptococcus or Staphylococcus
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Clostridium difficile is lecithinase _______
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negative, all other Clostridia are positive
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Most anaerobes are susceptible to first-line antimicrobials (T/F)
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True, susceptibility testing is usually not necessary
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Definitive ID of an anaerobe is necessary for treatment if ______
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a pure culture is developed from a normally sterile site, a known resistant species is isolated or a severe infection is not responding to antibiotics
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Streptomyces produces several _______ that have been utilized in medicine
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antibiotics (70-85% of medically important)
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Streptomyces is introduced into the body by _________ and then spreads _______
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tissue trauma, subcutaneously
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Treatment for Streptomyces is _____ and _______
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antibiotics and surgery
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Streptomyces is an acid-fast organism (T/F)
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False, this organism is not acid-fast
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Streptomyces does NOT reduce nitrate to nitrite (T/F)
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True
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Actinomyces has colonies with margins that appear like a _______ or ______
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molar tooth, raspberry
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Actinomycosis may be transmitted human to human (T/F)
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False
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Treatment for Actinomyces
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surgical drainage, excise damaged tissue, long-term antibiotic therapy
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Acid-fast bacteria resist staining with basic dyes due to _______
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thick cell well with mycolic acid and high lipid content
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The acid-fast stain utilizes what dye?
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Carbol fuschin
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Mycobacteria are intracellular bacteria (T/F)
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True
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Mycobacteria grow very slowly due to __________. Growth can take from ________.
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highly hydrophobic surface. 2-60 days.
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Tuberculosis incidence rates correlate with what kind of conditions across the world?
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poor socioeconomic conditions
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Approximately ______ of the world's population is infected with M. tuberculosis
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1/3
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M. tuberculosis symptoms of pulmonary disease
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coughing (sometimes with sputum or blood), chest pains, weakness, weight loss, fever, night sweats
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Extrapulmonary tuberculosis is known as _______ and is more common in ______ and ________ patients
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miliary tuberculosis, children, HIV-infected
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Presumptive identification of tuberculosis is based on:
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Patient medical history, presenting symptoms, physical exam, X-ray and detection of acid-fast bacilli from sputum sample
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Definitive identification of M. tuberculosis is based on:
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Lack of growth in BACTEC-NAP
Reduction of nitrate to nitrite Growth in TCH Niacin accumulation Appearance of microcolonies with serpentine cords on Middlebrook 7H10 after 5-10 days Growth on Middlebrook or L-J medium |
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When pathogenic, mycobacteria other than tuberculosis cause _______ infections
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opportunistic
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Photochromogenic MOTT organisms produce pigments _______
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only in the light
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Scotochromogenic MOTT organisms produce pigments ______
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in both the dark and the light
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______ is the most commonly isolated Mycobacteria species in the US
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M. avian complex
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MAC is acquired by _______. It has a reservoir of ______ and ______.
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inhalation or ingestion, animals, water
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Mycobacterium leprae is transmitted by _____ or _______.
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inhalation, person-to-person contact
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M. leprae is considered highly contagious (T/F)
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False, this pathogen is not considered highly contagious
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Tuberculoid leprosy is a ______ infection that results in _____ lesions with ______ involvement.
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localized, skin, nerve
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In immunocompetent people, a _____ response is mounted to M. leprae and recovery is usually spontaneous
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cell-mediated
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The optimal growth temperature for M. leprae is _______
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30 degrees celsius
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Characteristics of Aerobic Actinomycetes
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Morphology similar to fungi, gram positive bacilli, branching, filamenteous hyphae
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Nocardia stains partially ______
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acid-fast
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Nocardia is a facultative ________ organism
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intracellular
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Norcardia grows at what temperature?
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Wide range 22-37 degrees celsius
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Where is Nocardia found in the environment?
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In soil, worldwide
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Nocardia infections are normally seen in what population?
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immunocompromised
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Principal routes of infection for Nocardia
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Pulmonary (usually asteroides) or cutaneous (usually brasiliensis)
Direct contact via soil inhalation or skin trauma (not human to human) |
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Mycetoma
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granulomatous infection of dermal and subcutaneous tissue that includes swelling, draining sinuses and granules
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Mechanisms of disease for Nocardia
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resists oxidative killing by SOD and catalase production leading to granuloma formation
iron-chelator known as nocobactin |
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Treatment for Nocardia
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drainage, surgery and antimicrobials (but not penicillin, this organism is resistant)
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Streptomyces are _____ and gram _____ bacilli
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aerobic, positive
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Nocardia reduces nitrate to nitrate (T/F)
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True; Nocardia reduces nitrate; streptomyces does not
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Describe gram stain, morphology and oxygen requirements for the genus Actinomyces
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Gram stain/morphology: Gram Positive bacilli
Oxygen requirements: facultative anaerobe |
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MAC organisms (do/do not) produce pigment
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Do not; MAC (M. avium and M. intracellulare) are nonphotochromagens
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Crohn's disease is associated with which bacterial species?
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M. paratuberculosis
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Differentiate tuberculoid and lepromatous leprosy?
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Tuberculoid: localized: skin lesions, nerve involvement; spontaneous recovery usually occurs
Lepromatous: More serious: lesions, symmetric nerve damage, loss of cartilage and facial deformity; disseminated infection with immunodepressed pt's - must be treated with multi-drug therapy |
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M. bovis is nitrate ____, niacin ____, and TCH ____ (positive/negative)
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M. bovis is nitrate, niacin and TCH negative
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Porphyromonas is sensitive to ____ and resistant to _____
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Sensitive: Vancomycin
Resistant: Kanamycin and colistin |
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Prevotella is sensitive to _____ and resistant to _____
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Sensitive: Colistin
Resistant: Kanamycin, vancomycin |
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Bilophila is urease ____ and nitrate ____
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positive; positive
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a positive reverse CAMP test is presumptively indicative of which species?
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Clostridium perfringens
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C. difficile (does/does not) fluoresce chartreuse on BBA under UV light
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Does
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Which two anaerobes cause infection but are not part of normal flora?
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C. botulinum
C. tetani |