Irregular non-spore forming rods part 1, L. Monocytogenes and Erysipelothrix rhusiopathiae Flashcards
What are the Pyogenic Cocci
Pyogenic – Pus forming
Staphylococcus
S. aureus
Streptococcus
S. pyogenes (Lancefield Group A)
S agalactiae (LG B)
S. pneumoniae
Enterococcus viridant group (LG D)
Neisseria Moraxella Kingella
What are the irregular non-spore forming rods?
Listeria genus
Corynebacteria genus
Lactobacillus genus
Erysipelothrix rusiopathiae
Main difference between:
L. monocytogenes
and
L ivanovii
L. monocytogenes -> human pathogen, animals can be carriers but it is not pathogenic in them.
L. ivanovii –> animal pahtogen
Listeria monocytogenes physical and culture characteristics, habitat, and transmission
Small Gram-positive rod (2uM long), with a single flagella, uniform shape
cultured on agar or blood agar
Facultative anaerobic and Facultative intracellular
Beta-hemolyzing
Catalase positive
CAMP positive
Cold and Salt tolerant
Tolerant to proteolytic eznymes, stomach acid, and bile salts
Serologic classification: Ia, Ib, IVb
Found in animals GI and in some human GI
Zoonotic transmission by eating contaminated food or soil, or getting it into an open wound (common in butchers or animal workers)
Can reporduce in cold temps and is salt resistant, so it can be in contaminated milk or other foods
Human to human transmission is oral or transplacental
Infects patients with impaired cell-mediated immunity (it is intracellular so humoral immunity is not important), elderly, and infants, Transplant patients AND Pregnant Women who are often asymptomatic
What is unique about L. monocytogenes motility?
Non-motile by flagella at 37C
At 20C (room temperature or refridgerated) it is motile by flagella and can also reproduce
Flagella based movement is oxygen dependen t, as demonstrated by the picture
Within the body at 37C It moves within the cells by causing actin polymerization, mediated by the ActA protein Comet tails, or Actin rockets.
During this process, it can pass from cell-to-cell while remaining intracellular the entire time.
It can survive phagocytosis, and once inside of an endo-lysosome, the low pH activates pore-forming enzymes, releasing the bacteria into the cytosol.
The normal treatment for L. monocytogenes
Prevention
Ampicillin and Gentamycin,
Broad spectrum penicillin and aminoglycoside a classic synergistic treatment Ampicillin damages the cell wall, allowing better penetration for the Gentamycin to inhibit RNA transcription
Alternative treatment, Erythromycin
Resistant to: Cephalosporins
Prevention: Don’t eat raw or partially cooked foods, soft cheese
L. monocytogenes
Antigens
Virulence factors
Antigens:
H-antigen-> Flagella
Hemolysin
Virulence Factors:
Flagella
Hemolysins
Listeriolysin (phagosome lysis)
Phospholipase (phagosome lysis)
ActA (Actin polymerization, rocket polymerization)
Internalins (internalin A and B allow it to attach to epithelial cells, eterocytes, and M-cells)
L. monocytogenes clinical diseases
Neonatal early onset disease:
Infection occurs in utero or transplacentally. Usually causes abortion or stillbirth.
Or premature birth with Granulomatosis Infantiseptica, severe infection with absecess and granulomas in multiple organs. High mortality
Neonatal late onset disease:
Acquired during birth or soon after.
Presents 2-3 weeks after birth as meningitis or meningoencephalitis with septicemia
Infections in pregnant women
Pregnant women are considered somewhat immunocompromise.
Cell-mediated immunity is worst in the 3rd trimester.
May be asymptomatic, or with non-specific flu/cold symptoms.
OR
Meningitis
Immunocompromised patients:
Meningitis
In healthy adults:
Asymptomatic or mild flu/cold
OR
Acute, self-limited gastroenteritis: fever, nasuea, headache, myalgia, arthralgia (muscle and joint pain)
Laboratory diagnosis of L. monocytogenes
CSF is usually negative for bacteria
Gram-positive intracellular rods, and in blood
Serology types Ia, Ib, and IVb are pathogenic
Catalase positive
Beta-hemolysing
CAMP positive (side note, Strep group B are also CAMP positive)
Erysipelothrix rhusiopathiae
Morphology, cultivation
Gram positive rods.
non-spore forming.
Irregularly shaped, some curved or squigly and some straight, some in chains.
Culture:
On blood agar, forms small transparent (clear/very pale whitish) colonies
No hemolysis
Breakdown the name Ersipelothrix rhusiopathiae
Erysipelo - Ersipeloid - similar to the Erysipelas lesions in pigs. In humans it means a painful violet/purple/red lesion of the hand. Does not form pus.
Erysipelothrix rhusiopathiae
Epedimiology and clinical disease
Diagnosis
Treatment and prevention
Found in many animals as hosts, but causes erysipelas in swine
Transmitted strictly from animals to humans, zoonotic, by direct innoculation into open cuts. Butchers, Fishers.
Diagnosis: Biopsy or aspirates from the lesion, staining and cultivation
Symptoms:Erysipeloid lesions, usually of the hands
In rare widespread infections causes endocarditis or septisemia
Treatment and prevention:
Is usually self resolving in a few weeks, but is faster with Peniccilin. Prevention is to vaccinate the swine or animals that the patient is working with, and to use gloves.
