Listeria (ch 21) PDF Study Guide

Read Quiz Comprehensive Study on Listeria monocytogenes Overview Listeria monocytogenes is a significant pathogen, affecting both animals and humans with a high risk to certain populations through contam...

Read Quiz Comprehensive Study on Listeria monocytogenes Overview Listeria monocytogenes is a significant pathogen, affecting both animals and humans with a high risk to certain populations through contaminated food products. This comprehensive guide synthesizes various perspectives on Listeria monocytogenes, addressing its characteristics, pathogenesis, epidemiology, clinical manifestations, laboratory diagnosis, and measures for treatment, prevention, and control. Key Characteristics Morphology and Physiology Gram-positive rods: Listeria monocytogenes appears as short Gram- positive rods arranged in pairs or short chains. Facultative anaerobes: Capable of surviving with or without oxygen. Temperature Range: Grows at a broad temperature range, exhibiting weak beta hemolysis and salt tolerance. Motility: Motile at room temperature. Intracellular Pathogen: Capable of living inside host cells. Pathogenesis and Immunity Infection Mechanism https://www.studocu.com/en-us/notes 12/4/24, 7 11 PM Page 1 of 4 :  Survival Tactics: Survives stomach acids, enzymes, and bile salts. Cell Entry: Adheres to E-cadherin via Internalin A (InlA) and enters the cells. Phagolysosome Escape: Utilizes listeriolysin O and phospholipases to escape the phagolysosome. Cellular Movement: Manipulates the host cell's cytoskeleton and moves to neighboring cells using actin as a propeller through the bacterial protein ActA. Epidemiology Distribution Widely distributed in the environment and feces from mammals, birds, fish, and insects. Estimated 2,500 infections annually in the US. High-Risk Populations Neonates, the elderly, pregnant women, and immunocompromised individuals are at high risk. Outbreaks Significant Outbreaks: The 2011 outbreak was the second deadliest in the US with 147 infections and 33 deaths across 28 states. Recent Statistics: Between January 2010 and January 2015, ten patients were infected across four states, with three deaths in Kansas reported by the CDC. Clinical Diseases Neonatal Disease Early Onset: Transmitted transplacentally leading to severe outcomes. Late Onset: Acquired after birth, causing meningitis and septicemia. https://www.studocu.com/en-us/notes 12/4/24, 7 11 PM Page 2 of 4 :  In Healthy Adults Often asymptomatic or presents mild influenza-like illness. Invasive Infections: Meningitis is the most common form associated with invasive disease. Laboratory Diagnosis Diagnostic Techniques Gram Stain: Although not detectable in cerebrospinal fluid (CSF), it grows on conventional media. Tests: CAMP test and nucleic acids tests, including pulsed-field gel electrophoresis for epidemiological tracking. Treatment, Prevention, and Control Treatment Antibiotics: Most antibiotics are bacteriostatic; however, trimethoprim- sulfamethoxazole is bactericidal. Prevention and Control Combatting Listeria monocytogenes is challenging due to its ubiquitous nature. Regular monitoring of food products and strict hygiene standards are essential in preventing outbreaks. This guide aims to provide a thorough and in-depth understanding of Listeria monocytogenes, suitable for academic and study purposes. It covers essential aspects ranging from the pathogen's biological characteristics to their public health implications. https://www.studocu.com/en-us/notes 12/4/24, 7 11 PM Page 3 of 4 :  https://www.studocu.com/en-us/notes 12/4/24, 7 11 PM Page 4 of 4 :