《微生物学》课程PPT课件讲稿（英文版）Lecture 14 Legionella

History American Legion Convention in 1976 in Philadelphia hotel Respiratory distress and fever 200 affected 34 died BIOL 533 Lecture 14

BIOL 533 2 Lecture 14 History • American Legion Convention in 1976 in Philadelphia hotel – Respiratory distress and fever – 200 affected – 34 died

History Six months after outbreak cdc isolated bacteria from post-mortum lung tissue Inoculated lung tissue into peritoneal cavity of guinea pigs After animal became ill, removed its spleen and injected tissue into fertilized chicken eggs (rickettsial methodology) BIOL 533 Lecture 14

BIOL 533 3 Lecture 14 History • Six months after outbreak, CDC isolated bacteria from post-mortum lung tissue – Inoculated lung tissue into peritoneal cavity of guinea pigs – After animal became ill, removed its spleen and injected tissue into fertilized chicken eggs (rickettsial methodology)

History Organism was thought to be unique, given new genus and species name Legionella pneumophila Epidemiological search revealed outbreak in same hotel two years earlier o Culture problems because organisms Do not grow on common laboratory media Do not readily stain BIOL 533 Lecture 14

BIOL 533 4 Lecture 14 History • Organism was thought to be unique, given new genus and species name: Legionella pneumophila – Epidemiological search revealed outbreak in same hotel two years earlier • Culture problems because organisms: – Do not grow on common laboratory media – Do not readily stain

Microbial Physiology and structure Family Legionellaceae One genus: Legione∥a 25 species and 42 serotypes Legionella pneumophila responsible for 85% of infections(serotype 1 most common) BIOL 533 Lecture 14

BIOL 533 5 Lecture 14 Microbial Physiology and Structure • Family Legionellaceae • One genus: Legionella – 25 species and 42 serotypes – Legionella pneumophila responsible for 85% of infections (serotype 1 most common)

Microbial Physiology and structure Species can be differentiated by DNA homology Cell wall fatty acids Biochemical testing Immunological serotyping BIOL 533 Lecture 14

BIOL 533 6 Lecture 14 Microbial Physiology and Structure • Species can be differentiated by: – DNA homology – Cell wall fatty acids – Biochemical testing – Immunological serotyping

Microbial Physiology and structure Morphology Gram rods(pleomorphic on artificial media) Do not stain well except with special silver stain Culture: do not grow in ordinary lab media, even though they are aerobic organisms Require high concentration of cysteine and are inhibited by sodium ions and aromatic compounds BIOL 533 7 Lecture 14

BIOL 533 7 Lecture 14 Microbial Physiology and Structure • Morphology – Gram— rods (pleomorphic on artificial media) • Do not stain well except with special silver stain – Culture: do not grow in ordinary lab media, even though they are aerobic organisms • Require high concentration of cysteine and are inhibited by sodium ions and aromatic compounds

Microbial Physiology and structure Media developed have Charcoal to absorb aromatic compounds Non-sodium ion buffer Antibiotics to suppress other organisms Dyes to make colonies visible on solid media BIOL 533 Lecture 14

BIOL 533 8 Lecture 14 Microbial Physiology and Structure • Media developed have: – Charcoal to absorb aromatic compounds – Non-sodium ion buffer – Antibiotics to suppress other organisms – Dyes to make colonies visible on solid media

Pathogenesis Encounter: aquatic, found in lakes and streams Large numbers in polluted water around power stations Can live in chlorinated drinking water Normally found in hot water tanks of buildings Get into pipes and multiply in sediment and accumulate over period of years Do not spread from person to person Sediment provides shelter as well as nutrition for other BIOL 533 bacteria that can supply cysteine Lecture 14

BIOL 533 9 Lecture 14 Pathogenesis • Encounter: aquatic; found in lakes and streams – Large numbers in polluted water around power stations – Can live in chlorinated drinking water – Normally found in hot water tanks of buildings • Get into pipes and multiply in sediment and accumulate over period of years – Do not spread from person to person – Sediment provides shelter as well as nutrition for other bacteria that can supply cysteine

Pathogenesis Entry, spread, and multiplication Entry: inhalation of organisms Incubation period: 2-10 days Initial host response: acute inflammatory response of aveoli and then bronchioles (similar to pneumococcal infection) Neutrophils accumulate followed by macrophage BIOL 533 Lecture 14

BIOL 533 10 Lecture 14 Pathogenesis • Entry, spread, and multiplication – Entry: inhalation of organisms • Incubation period: 2-10 days – Initial host response: acute inflammatory response of aveoli and then bronchioles (similar to pneumococcal infection) • Neutrophils accumulate followed by macrophage

Pathogenesis Different from pneumococcal infection Organisms located inside of macrophage Inhibit lysosomal fusion and acidification of phagocyte BIOL 533 Lecture 14

BIOL 533 11 Lecture 14 Pathogenesis – Different from pneumococcal infection • Organisms located inside of macrophage • Inhibit lysosomal fusion and acidification of phagocyte