Gram Pos Bacilli Exam 2 Flashcards
What organisms are of interest in this section?
Bacillus, Corynebacterium, and Listeria
Which Bacillus species are not considered normal flora?
B. cereus, B. circulans, B. licheniformis, B. subtilis
Bacillus spp. characteristics?
Large, Gram + Rods
Produces spores
Most are motile, ferment glucose, catalase +
Bacillus anthracis general characteristics?
Gamma hemolysis Non-motile Encapsulated (inhibits phagocytosis) Produces endospores Disease of livestock **Causative agent of anthrax in humans**
ID for Bacillus anthracis?
Colonies- large, opaque, green-gray to white, tenacious
Ground glass appearance MEDUSSA HEAD
What is the BS level done on Bacillus anthracis for preliminary testing?
Level 2
Confirmative ID at reference labs are Level 3
What are the 3 human forms of anthrax?
Cutaneous-malignant pustule, typically not fatal.
Pulmonary or Woolsorter’s disease- inhale spores (rare-usually fatal).
Gastrointestinal- ingestion of contaminated meat (rarest form, fatal 25-60% of the time).
Anthrax is contagious or not contagious?
Not contagious from person to person
What is the treatment of anthrax?
Ciprofloxacin, Doxycycline
Resistant to penicillin
What is associated with Bacillus cereus? What is the preferred specimen?
Food poisoning
The food itself
ID for Bacillus cereus?
Lavender colonies with slight green tinge on SBAP
Beta hemolytic, catalase +, motile
Bacillus stearothermophilus is used for?
Control organism in autoclave effectiveness
List and describe the agents of bioterrorism.
Category A- highest risk to public health (Clostridium botulinum, Bacillus anthracis, Yersinia pestis).
Category B- have moderate to low mortality rates (Brucella spp.).
Category C- emerging pathogens.
What is Listeria and Corynebacterium characteristics?
Gram pos rods Catalase + Non-acid fast Non-spore forming Both are facultative anaerobes
What is the transportation of Listeria monocytogenes?
Ingestion of raw vegetables, contaminated dairy and food products.
Has been documented to cross the placenta from mother to the developing fetus.
What are the virulence factors of Listeria monocytogenes?
Listeriolysin O- pore forming capabilities. Has hemolytic and cytotoxic capabilities.
Internalin- induces phagocytosis (gets in cells).
Act A- induces cellular extensions on phagocytic cells that are infected with microbe. Helps spread microbe.
What are Listeria monocytogenes characteristics?
Beta hemolysis. White, smooth translucent. Bile esculin+
Gram pos rods to coccobacilli in pairs or chains. Don’t confuse with Group A or B beta-hemolytic Streptococci.
What is the incubation of Listeria monocytogenes?
30-35 degrees C
What is the treatment for Listeria monocytogenes?
Ampicillin
What is the presumptive ID for Listeria monocytogenes?
End over end tumbling motility.
Umbrella shaped motility pattern via stab in semi-solid agar.
If isolate small gram positive rod, catalase pos, with narrow zone of beta hemolysis, suspect L. monocytogenes.
How can L. monocytogenes can be differentiated from other Listeria spp.?
A positive CAMP test or Hippurate test
How to prevent Listeria monocytogenes spread?
Wash raw produce, don’t cut raw meats on wood cutting board with veggies, wash your hands, and keep fridge at 40 degrees F or lower.
General characteristics of Corynebacterium spp.?
Non-motile, non-acid fast, and pleomorphic
Resemble Chinese letters
Which Corynebacterium spp. is not considered normal flora?
C. diphtheriae
True/false? Diphtheriods are often considered normal flora and include C. diphtheriae.
False. Normal flora, but does NOT include C. diphtheriae
What does the “Chinese letters” appearance come from?
Irregular snapping during cell division
What is selective media that can be used for Corynebacterium spp.?
Loeffler’s Media
Cystine tellurite media- brown halo
Tinsdale agar- gray-brown halo
Which biotype is the most severe and virulent in Corynebacterium spp.?
Gravis type
Which organism has metachromatic granules?
Corynebacterium spp.
Methylene Blue stain allows for visualization.
What is the presumptive ID for C. diphtheriae?
Urease -, halo on Tinsdale agar, and non-motile
What vaccination can be used for the C. diphtheriae?
DTaP-children
Tdap-adolescents and adults
What organism is associated with struvite stone formation and a strong urease activity?
C. urealyticum
Which organism has the biggest risk factors for infection associated with catheters and prosthetic heart valves.
C. jeikeium
What is C. jeikeium resistant to? Drug of choice?
Resistant: penicillin and cephalosporins
Drug of choice: Vancomycin
Which organism is associated with localized red skin lesions (erysipeloid) and veterinary and meat handlers are most at risk?
Erysipelothrix rhusiopathiae
General characteristics for Erysipelothrix rhusiopathiae?
Gram positive, alpha to gamma hemolysis
Thread-like rods
Catalase -, non-spore forming, produces H2S on slant.
True/false? Lactobacillus spp. are normal flora of mouth, GI, and vagina.
True.
Usually contaminant
Which organism is the causative agent of clue cell formation (epithelial cells covered with adherent bacteria observed in vaginal smears)?
Gardnerella vaginalis
