Aerobes - Exam 8 Flashcards
What type of anaerobe is described?
Can handle brief exposure to O2 and does not grow well at RT
Obligate anaerobe
What type of anaerobe is described?
Incapable of growth after O2 exposure.
Strict obligate anaerobe
What type of anaerobe is described?
Can grow in low O2 concentrations; most clinically significant anaerobes fall under this category.
Moderate obligate anaerobe
What type of anaerobe is described?
Limited or scant growth in normal CO2 conditions.
Aerotolerant
What type of anaerobe is described?
Grows with or without O2.
Facultative anaerobe
What is an exogenous anaerobe?
An anaerobe that is not part of the normal flora that is causing disease.
What is an endogenous anaerobe?
Normal flora that has spread away from its normal site and is causing infection.
What are three recommended specimen types for anaerobes?
Blood, bone marrow, and aspirated material
What are three not recommended specimen types for anaerobes?
Throat swabs, vaginal swabs, and voided urine
When is testing for anaerobes necessary?
When the patient is suffering from a serious infection, recurring infections, and/or has a positive blood culture.
What are 4 ways that anaerobic bacteria may be collected and transported?
In a blood culture bottle with a syringe, in a syringe, in a Port-a-Cul tube, and/or in a vacutainer specimen collector.
What are the two ways that a vacutainer ensures O2 is not present?
There is a catalyst that precipitates O2 as H20 and a O2 detector that will present a color change in the presence of O2
What is CDC blood agar and what is it used for?
CDC blood agar contains vitamin K and hemin and is used for recovering anaerobic bacteria.
What is PEA agar and what is it used for?
PEA agar is phenylethyl alcohol agar and is used to recover gram positive organisms and inhibit gram negatives and swarming proteus - aerobically!
What is CDC KV agar and what is it used for?
It is CDC agar with added kanamycin and vancomycin to inhibit the growth of facultative aerobic organisms - anaerobically!
What is BBE agar and what is it used for?
BBE agar is Bacteroides Bile Esculin agar. Contains gentamicin and 20% bile. It is used to test for esculin hydrolysis and is useful for recovering Bacteroides species along with some species of the Fusobacterium and Enterococcus.
What is egg yolk agar and what is it used for?
Egg yolk agar has the components to test for the utilization of lipase, lecithinase, and proteolysis. It is used for recovering Fusobacterium, Clostridium and Prevatella.
Note: lipase breaks down fats to create an oil on the agar surface
What does enriched thioglycolate broth contain?
glucose, hemin and vitamin K
What does a CCFA agar plate contain? What organism has a distinct appearance on this agar? Why is it used for this organism?
Cyclosporine, cefoxitin, and fructose. C. diff appears yellow on the agar - the agar helps inhibit intestinal flora.
What are three methods of anaerobic incubation?
Anaerobic jar, gas pack pouch, and anaerobic chamber
What are 5 macroscopic observations that may be made for anaerobic cultures?
Foul odor, blood present, black or necrotic tissue, sulfur granules and purulence
What might you do differently when gram staining an anaerobic organism?
Leave the safranin on for longer
What is the CDC KV plate specifically good for recovering?
Gram negative anaerobes
What are some clues you may have an anaerobic bacteria on agar?
Pitting, crumb-like colonies, brown/black colonies with brick red fluorescence, molar tooth colonies, double zone of hemolysis, and swarming of the plate
What must the diameter be for the SPS disc test to be considering sensitive?
> or = to 12mm
Organism ID: Gram negative bacilli with rounded ends, grows on 20% bile, and is resistant to V, K and C.
Bacteroides fragilis group
Organism ID: Gram negative pleomorphic bacilli with a fried egg colony morphology, grows on 20% bile, and is indole and lipase negative.
Fusobacterium mortiferum
Organism ID: Gram negative pleomorphic bacilli (short and plump) with a fried egg colony morphology, grows on 20% bile and is indole variable.
Fusobacterium varium
Organism ID: Gram negative pleomorphic, knob shaped bacilli, umbonate colony morphology, 20% bile growth is variable, indole and lipase are positive.
Fusobacterium necrophorum
Organism ID: Gram negative spindle-shaped bacilli, breadcrumb-like colony morphology, growth on 20% bile is negative, indole is positive and the agar has started to green when bringing it into aerobic conditions.
Fusobacterium nucleatum
Organism ID: Gram negative bacilli, obligate anaerobe, the colony is pitting the agar and is small and translucent, negative for growth on 20% bile, urease positive, nitrate reductase positive, resistant to V.
Bacteroides ureolyticus
Organism ID: Gram negative bacilli, black/brown colonies with brick red fluorescence, asaccharolytic, grows on 20% bile, indole positive, resistant to K and C.
Porphyromonas
Organism ID: Gram negative bacilli, black/brown colonies with brick red fluorescence, moderately saccharolytic, resistant to V and K, C variable.
Prevotella
Organism ID: Gram positive bacilli, club shaped with some branched and unbranched, has a rough, molar tooth colony morphology, forms sulphur granules, grows best anaerobically, nitrate reductase positive, and esculin hydrolysis positive.
Actinomyces israelii
Organism ID: Gram positive bacilli, smooth or rough colony types that becomes tan with age, aerotolerant, nitrate reductase positive, urease positive, and esculin hydrolysis variable.
Actinomyces naeslundii
Organism ID: Gram positive bacilli, develops a red color of the CDC agar after time, is aerotolerant and microaerophilic, is nitrate reductase positive.
Actinomyces odontolyticus
Organism ID: Gram positive bacilli, aerotolerant, catalase positive, urease positive, and nitrate reductase positive.
Actinomyces viscous
Organism ID: Gram positive bacilli - small, strict obligate anaerobe, biochemically inactive.
Actinomyces meyeri
Organism ID: Gram positive bacilli that look like birds in flight, small white colonies, grows better anaerobically, indole positive, catalase positive, nitrate reductase positive.
Propionibacterium acnes
Organism ID: Gram positive bacilli that appear small and stubby, small grey, translucent colonies (very slow growth - pinpoint at 3 days), catalase positive, indole variable, nitrate reductase positive, and resistant to C.
Eubacterium lentum
Organism ID: Gram positive bacilli that appear forked at the ends, aerotolerant, microaerophilic, negative for indole, catalase and nitrate reductase, positive for esculin hydrolysis.
Bifidobacterium dentium
Organism ID: Gram positive bacilli that form long chains, appears alpha hemolytic, aerotolerant and microaerophilic, catalase negative.
Lactobacillus spp.
Organism ID: Gram positive cocci, sweet and putrid odor, obligate anaerobe, indole negative, nitrate reductase negative, sensitive to SPS disc.
Peptostreptococcus anaerobius
Organism ID: Gram negative cocci (looks like an over decolorized staph), catalase variable, resistant to V.
Veillonella spp.
Organism ID: Spore forming Gram positive bacilli (chubby, long rods that look like Bacillus), double zone of hemolysis on plate, does not grow on 20% bile, aerotolerant, lecithinase positive, reverse CAMP positive, Nagler test positive, resistant to C.
Clostridium perfringens
Organism ID: Spore forming Gram positive bacilli, medusa head colonies, will also swarm plate within 24-48 hours, positive for esculin hydrolysis.
Clostridium septicum
Organism ID: Spore forming Gram positive bacilli, has a distinct “barnyard” smell and may grow yellow on CCFA, this organism is ID’d using direct detecting EIA methods
Clostridium difficile
Organism ID: Spore forming Gram positive bacilli with subterminal spores, the gram stain is indicative and it is further ID’d using serological methods.
Clostridium botulinum
Organism ID: Spore forming Gram positive bacilli with terminal spores (“tennis rackets”), will swarm on CDC, is lecithinase negative and lipase negative.
Clostridium tentani
