Listeria and Erysipelothrix

The aerobic, non-spore-forming, gram-positive rods 1) well-recognized human pathogens (e.g., Corynebacterium diphtheriae, Mycobacterium tuberculosis), 2) others are primarily animal pathogens that can cause human disease (e.g., Erysipelothrix rhusiopathiae, Rhodococcus equi) 3) opportunistic pathogens typically infecting hospitalized or immunocompromised patients (e.g., Corynebacterium jeikeium). Identification of the organisms in the laboratory Gram-positive rods that are uniform in shape include Listeria and Erysipelothrix The coryneform rods (which include the genus Corynebacterium) comprise a large group of irregularly shaped rods long-chain mycolic acids in their cell walls. : acid-fast stain was developed : Nocardia, Rhodococcus, Mycobacterium BOX 26-1. Listeria and Erysipelothrix Organism Historical Derivation Listeria Listeria, named after the English surgeon Lord Lister L. monocytogenes monocytum, a blood cell or monocyte; gennaio, produce (monocyte producing; membrane extracts stimulate monocyte production in rabbits, but this is not seen in human disease) Erysipelothrix Erythros, red; pella, skin; thrix, hair (thin, hairlike organism that produces a red or inflammatory skin lesion) E. rhusiopathiae rhusios, red; pathos, disease (red disease)

Listeria monocytogenes History - 1926: isolated form rabbits with mononucleosis - 1927: given its name to honor surgeon lord Lister - 1929: isolated from human with mononucleosis-like disease

Physiology and structure - short (0.4 to 0.5 × 0.5 to 2.0 μm) - nonbranching, gram-positive, - facultatively anaerobic rod - growth at a broad temperature range (1°C to 45°C) and in a high concentration of salt. - motile at room temperature - less so at 37°C, end-over-end tumbling motion : cold enrichment (growth 4oC) - weak β-hemolysis when grown on sheep blood agar plates. - bacteria are widely distributed in nature, - human disease is uncommon and is restricted to several well-defined populations: neonates, the elderly, pregnant women, and patients with defective cellular immunity. Gram-stain preparation showing L. monocytogenes in cerebrospinal fluid

Pathogenesis and Immunity Intracellular Growth - can grow macrophages, epithelial cells, cultured fibriblast - Entry : six or more leucine-rich proteins internalins (eg., InlA, InlB, InlC)  glycoprotein receptors (host cells) - bacterium escapes from host vacuole (phagolysosome) : activates exotoxin (listeriolysin O), two phospholipase C - Release into cytosol - Rapid division - Move to cell membrane (ActA) becomes encapsulated by short actin filaments facilitates movement to periphery with protrusion and then penetration to neighboring cells never exposed to humoral immunity Avoiding antibody-mediated clearance - β-hemolysin (listeriolysin O), phospholipase : produced by virulent strain only : oxygen labile : antigenic : disrupts phagolysosome

Cell-cell transmission Entry Internalins Escape Listeriolysin O Phospholipase C Fusion with another cell replication actin tail extrusion ActA

Susceptible host and source of listeriosis Healthy children and adults asymptomatic carriage Pregnant women septicemia neonatal disease Immunocompromized: meningitis Superinfections Food products Direct contact Environment Mammals Birds Fish Insect

Clinical diseases Neonatal Disease Mother has no symptomatic illness Two forms of neonatal disease 1) Early-onset disease (조기형 감염증) Granulomatosis infantiseptica - infection of fetus in utero - can lead to abortion, disease at birth (sepsis, pneumonia, fetal distress, seizures, rash, abscesses, and granulomas - High mortality rate 2) Late-onset disease (지연형 감염증) - acquired at or soon after birth - Exposure on vaginal delivery - can result in meningitis or meningo-encephalitis with sepsis within 2-3 weeks

Adult Disease - Normal adult are resistant - Common organism in HIV infected and other immunosuppressed patients : Gastroenteritis : Septicemia :Meningitis – patients with organ transplants, cancer - pregnant women Treatment, prevention, and control - Penicillin or ampicillin alone or in combination with gentamicin prevention and control are difficult : ubiquitous and most infections are sporadic avoid eating raw or partially cooked foods of animal origin, soft cheeses, and unwashed raw vegetables. A vaccine is not available, not evaluated prophylactic antibiotic therapy

Erysipelothrix rhusiopathiae PHYSIOLOGY AND STRUCTURE gram-positive, non-spore-forming, facultatively anaerobic rod distributed worldwide in wild and domestic animals. pleomorphic, with a tendency to form filaments as long as 60 μm ("hairlike") microaerophilic, preferring a reduced oxygen atmosphere and supplemented carbon dioxide (5% to 10%). grayish, α-hemolytic colonies on blood agar are observed after 2 to 3 days of incubation Animal disease-particularly in swine-is widely recognized, but human disease is uncommon. Catalase-negative, nonmotile Produce H2S

Diagnosis and treatment Erysipeloid - Occupational disease of meat and fish handlers - Caused by Erysipelothrix rhusiopathiae Diagnosis and treatment - Diagnosis : History and lesion : Culture of specimen - Treatment : Penicillin