1. Listeria

2. Erysipelothrix

1. Corynebacterium

2. Propionibacterium

3. Mycobacterium (Acid-fast)

4. Actinomycetes, Nocardia

motility: end-over-end tumbling @ 20-25*C (NOT 37*C) in liquid medium OR umbrella motility in agar medium (from tumbling motility test)

non-fastidious

dx: culture from blood, CSF, placenta, & amniotic fluid

ubiquitous saprophyte (humans are only accidental hosts)

transmission: foodborne pathogen (person->person trans NOT common)

can penetrate placenta barrier

1.transcriptional regulator => change from saprophyte --> human pathogen

*highly coordinated 

2.motility: actin & flagella-mediated

3.adherence

4.internalin (InlA, InlB, & InlC): helps L cross BBB & feto-placental barrier

5.listeriolysin (LLO): *most important* pore forming toxin; helps rupture endosomes to release L -> cytosol AND translocation of 2 listerial phospholipases (lyse endosomes)

Listeria monocytogenes

once L. monocytogenes enters the cell, it never leaves (mostly an intracellular life cycle: listerial ActA helps actin nucleation --> build a tail --> filaments move through cytoplasm & propel listeria intra-/inter-cellularly --> de-polymerize/turnover)

1. gastroenteritis: more severe in compromised CMI patients

2. bacteremia: assoc w/ fever, chills, myalgia, arthralgia

3. meningitis: 5-10% community-acquired; meningeal sign uncommon; neutrophils NOT elevated (be/c CMI/T cell response is most important)

*meningoencephalitis: most common manifestation of listeriosis in adults & childrens

dangerous

100% transmission to fetus

women usually bacteremic

common complication: premature delivery & stillbirth

acquisition: in-utero

fatality: 50%

causes: granulomatosis infantiseptica

most common in: liver, lung, kidney, brain, spleen, & skin

acquisition: shortly after birth (from mother/other babies in nursery)

may cause: meningoencephalitis 

Erysipelothrix rhusiopathiae

no spores

non-motile

skin biopsy: usually negative

acquisition by occupational exposure (butchers, poultry workers)

erysipeloid

septicemic diseases

high G/C content in chrom

short chain mycolic acid

non acid-fast rods

no capsule

colonizes URT

most important pathogen: C. diphtheria

humans are the only host (anyone recovering/latent/carrying can transmit)

diphtheria toxin (Dtx): produced w/o Fe; two effects (endocytosis & inhibit protein syn)

most prominent toxicity: heart & kidney; local cytotoxicity => "pseudomembrane" mostly in pharynx

massive edema of submandibular/paratracheal region => tonsillar swelling

associated w/: foul breath, thick speech & stridous breathing

infections: 1. nasopharyngeal diphtheria: mucosal ulcers covered w/ PM; may lead to airway obstruction

2. cutaneous diphtheria: lesions covered by PM; *greater risk of transmission than nasal

toxigenic: 1. septicemic diphtheria: toxin travels via circ to dist organs => paralysis & CHF

confirmation: req culture

white colonies on blood agar

black colonies on blood tellurite agar

presentation:

severe pharyngitis, dark pharyn PM cannot removed w/o blood, difficult swallowing, resp compromised, signs of systemic disease (incl. myocarditis)

normal skin flora

=> erythrasma (chronic superficial infection of intertriginous regions; incr freq in tropical areas; usually asymptomatic)

produces propionic acid and => acne vulgaris

gram+ ANAEROBIC

resembles Corynebacterium (morphologically, however it is not toxigenic)