Gram Positive Rods and Aerobic Actinomycetes 9/4/15 Flashcards
Describe the key identifying characteristics of Bacillus anthracis.
- Spore-forming
- Gram Positive Rods
- Aerobe
- Non-motile (unlike other Bacilli)
-Non-hemolytic
-Susceptible to penicillin, ciprofloxacin, and doxycycline (when possible terrorist origin)
What bacterial strain can be identified by the following characteristics:
- Non-spore forming
- Gram positive rod
- Beta-hemolytic (like Group B strep)
- Catalase POSITIVE
- Tumbling motility (motile at RT only) = Umbrella motility
Listeria monocytogenes
Describe key identifying characteristics of Erysipelothrix rhusiopathiae.
-Pleomorphic Gram + rods
-Form long filaments (Hair-like)
-Fac anaerobes
-Slow growth (2-3 days)
-Small, grayish, alpha hemolytic colonies
-Catalase NEGATIVE
- non-motile
- weakly fermentative
-Produces H2S on triple sugar iron agar (TSI): turns the media BLACK
What bacterial strain is identified by the following characteristics:
- Pleomorphic Gram positive rods
- Resemble Chinese “letters”: V’s and X’s
- Fac anaerobes
- Small white non-hemolytic colonies
Corynebacterium diphtheriae
-Commonly called “diphtheroids”
Describe key identifying characteristics of Arcanobacterium hemolyticum.
- Non-spore forming
- Gram Positive Rods
- Formation = irregular, club-shaped/curved
- Catalase NEGATIVE
- Beta-hemolytic (similar to Group A strep)
What bacterial strain is identified by the following characteristics:
- Gram + Rods
- Partially acid fast (stains pink)
- Mycolic acid in cell wall
- Strict aerobe
- Nocardia
- Organism in the Actinomycetes group
Describe the epidiology and clinical presentation of infections caused by B. anthracis.
- Anthrax = “coal”
- Category A biothreat agent
- Inoculation, 2. Ingestion and 3. Inhalation (bio weapon):
- Cutaneous:
- Inoculation, 2. Ingestion and 3. Inhalation (bio weapon):
-
Painless papule (20% mortality)
2. GI Anthrax: - Ulcers, nausea, vomiting, malaise, bloody diarrhea (100% mortality)
3. Inhalation: Fever, edema, enlargement of mediastinal lymph nodes (widening of mediastinum see on chest Xray)
What bacterial species is associated with the following epidemiology:
- Plants, meats, dairy contaminated with water/animal feces
- Undercooked and unpasteurized foods (“raw milk”)
- Soft cheeses, veggies, cold cuts contaminated
Listeria monocytogenes
Describe the epidemiology and clinical presentation of infections caused by Erysipelothrix rhusiopathiae.
-Colonization high in swine and turkeys
- Human infection acquired from animals, primarily occupational:
- butchers
- meat processors
- farmers
- fish handlers, etc.
- Cutaneous infections
- Erysipeloid infections:
- localized skin infection, on hands
- appears violaceous with a raised edge
- suppuration uncommon (different from streptococcal erysipelas)
- Septicemic infections:
- Uncommon
- Usually present with endocarditis
- Treatment: PCN is DOC
What bacterial species is associated with the following epidemiology and clinical presentation:
- Almost always non-pathogenic skin flora
- Also colonizes: Upper Respiratory Tract, GI Tract and Urogenital Tract
- Infection transmitted by respiratory droplets/direct contact with cutaneous infection
- Pharyngitis with patchy exudates on tonsils, uvula, soft palate
-Tough gray pseudomembrane = respiratory obstruction and suffocation
Corynebacterium diphtheriae
Describe epidem. and clinical presentation of A. hemolyticum infection.
- Isolated mostly from young adults
- Symptomatic pharyngitis, fever, occ. cutaneous rash
- Some with pseudomembranes on pharynx/tonsils, submandibular lymphadenopathy
- Also isolated from wounds, abscesses and blood of pts with septicemia and endocarditis
What bacterial species is associated with the following epidemiology and clinical presentation:
- Pulmonary diseases
- Cutaneous infections
- CNS infections (brain abscesses)
- Exogenous infections acquired by inhalation (pulm) or traumatic (cutaneous) introduction
- Immunocompetent pts: chronic pulmonary disease
- Immunocompromised pts: T-cell deficiencies
Nocardia spp.
What bacterial species is associated with the following clinical presentation:
- Neonates: disseminated abscesses and granulomas in multiple organs, meningitis with septicemia
- Elderly: Influenza-like illness with or without gastroenteritis
- Pregnant women/pts with cell-mediated immune defects: bacteremia with hypotension and meningitis
L. monocytogenes
What are treatment and prevention options of Listeria monocytogenes infections?
- PCN or ampicillin +/- gentamycin
- Resistant to cephalosporins
- High risk ppl should avoid eating raw/partially cooked foods, soft cheeses, and unwashed fruits and veggies
What are possible treatment options for Nocardia spp?
Sulfonamides and proper wound care
Explain why pts with defects in cellular immunity are susceptible to infections with L. monocytogenes?
The bacterium has the ActA gene = uses host cell actin to move into adjacent cells without exposure to the immune system in serum
Name 2 aerobic gram + rods that can cause food poisoning.
- Bacillus cereus
- Listeria monocytogenes
List the diseases associated with Nocardia, Rhodococcus, and Tropheryma.
- Pulmonary, CNS, Cutaneous infections
- Pulmonary, opportunistic infections
- Whipple’s Disease (systemic, GI disease)
