Rods Flashcards
Regular Rods
Listeria. Erysipelothrix
Irregular rods
Corynebacterium. Actinomycetes. Mycobacterium. Propionibacterium. Nocardia
Charac. Listera monocytogenes
Small, Gram (+) coccobacilli in pairs. Can grow in refridgerator. Foodborne mortality.
L. monocytogenes Virulence
Can penetrate placental barrier, withstands proteases/acid/bile, Mediated by PrfA. LLO
Listeriolysin
A cholesterol dependent cytolysin. Helps to rupture endosomes/releasing Listeria. If has more cytotoxic LLO, listeria is less virulent
Motility of L. monocytogenes
Flagella-mediated (only respiratory). Actin-mediated (helps to spread in host)
Adherence of L. monocytogenes
Bacterial alpha-D-galactose binds E-cadherin of intestinal cells
Internalin (Inl A/B/C)
Promotes bacterial endocytosis. Helps Listera cross BBB and feto-placental barriers
What helps listeria build a tail?
Listerial ActA helps with the actin nucleation
Immunity towards listeria
Cell mediated. NO ANTIBODIES
Listeria in healthy adults
Gastroenteritis (about 48 hrs after) for about 2-3 days
Listeria in pregnant women
100% risk of vertical transmission to fetus. Can cause premature delivery and still birth
Listeria and neonates
Early onset: High mortality, Granulomatosis infantiseptica. Late onset: meningoencephalitis
What is cultures to find Listeria?
Blood, CSF, placents, amniotic fluid
Positive tests for Listeria
Catalase and CAMP test
End to end tumbling motility
Caused by Listeria in liquid medium. Creates umbrella motility in agar medium
Charac. Erysipelothrix Rhusiopathiae
Pleomorphic. Gram (+) rod. Slow growing
Epidemiology of E. rhusiopathiae
Veterinary pathogen (swine and turkey). Occupational exposure
What causes erysipeloid in humans?
E. Rhusiopathiae
Erysipeloid
Localized cutaneous lesion. Painful/Pruritic but usually self limiting
Identification of E. rhusiopathiae
Gram (+). Not fastidious but grows slow (need at least a week before considered negative). Neg catalase/motility
How to distiguish E. rhusiopathiae from L. monocytogenes
Listeria is catalase (+) and motil
Corynebacterium
Short, mycolic acids. Non-acid fast irregular rods. Colonizes skin and URT
Most important virulence factor of c. diphtheriae
Diphtheria toxin (DTx)
What makes DtxR important to C. diphtheriae?
It’s an iron sensor bc it is an iron dependent production bacteria
Effect of Diphtheria toxin
inhibition of protein synthesis. Leads to pseudomembrane. Typically toxic in kidneys and heart. Is irreversible once in the cell. One toxin cal inactivate all ribosomes in the cell
Nasopharyngeal diphtheria
Sore throat/fever. Neck edema in adv stages. Mucosal ulcer may be present. Larger pseudomembrane=poorer prognosis. PM cannot be removed. Resp difficulty. Myocarditis
Cutaneous Diptheria
Punched-out ulcerative lesion with necrotic sloughing or PM
Septicemic diphtheria
Toxin reaches distant organs via circulation. Cause cause fatal heart failure and polyneuritis.
ID of C. diphtheriae
White on blood agar. Black on blood tellurite agar.
Corynebacterium minutissimum
Gram (+). Normal in skin flora. Infects inter-triginous regions. Invades upper 1/3 of stratum corneum. Causes Erthrasma
Erythrasma
Worldwide disease. More in tropical areas. Usually presents with dark skin discoloration
Propionibacterium Acnes
Gram (+) anaerobic rod. Produces propionic acid. Non-toxigenic.
Epidemiology of P. Acnes
Common in pilosebaceous glands. Skin changes in puberty increases bacterial growth.
Main cause of acne vulgaris
Propoinibacterium acnes
