Yersinia Flashcards
Yersinia sp
Non lactose fermenting gram neg rods
Motile (except Y. pestis, which causes plague)
Yersinia enterocolitica and psudotuberculosis
Zoonosis found in intestinal tract of wild mammals, birds, and domestic mams (commensals/reservoir for infection which can lead to food poisoning and diarrheal disease). Bird may act as amplifier host bc they shit everywhere and transfer organism mechanically. Both grow in wide temp range (4-42o)
enterocolitica causes sporadic abortion in ewes, gastroenterocolitis in humans, and sub clinical enteric infections in pigs and wild animals
Psudotuberculosis- humans enterocolitis or mesenteric lymphadonitis, sporadic abortion in cow, sheep and goat, and enteritis in young animals (sub clinical common in older) and mesenteric lymphadenitis causing severe abdominal pain which presents as appendicitis in farm animals. Also, common in caged birds and rodents, causing septicemia and massive number of deaths in pet stores
Yersinia pestis
In endemic areas, wild rodents are important reservoirs of infection. Fleas, esp Oriental rat flea transmit the infection to man and other animals
Cats more likely to show signs of infection bc eat rodents
Y. ruckeri
Causes perioral haemorrhagic inflammation in fish
Yersinia pathogenesis
Pathogenic enteric yersinia invade M cells of peyers patches and prevent phagocytosis
Virulence on plasmid and chromosomal factors which are required to survive and inhibit phagocytosis
Y. enterocolitica nd pseudotuberculosis are enhanced by yops (type 3 secretion system) which interfere with normal function of host phagocytic cells
Allows extracellular bac to adhear to surcafe of host cells and secrete/inj bac effector proteins (yops) into cytosol to disable/alter function. In GI mucosa, back precent phago and replicate in mesenteric lymph nodes and can develop necrotioc lesions and neutrophil infiltration
Y clinical infections
Pseudotb generally subclinical, but enteric disease common in farmed animals in Oz/NZ. Septicemia occurs in lab rodents and get from other rodents or contaminated food. In birds, overcrowding, sudden death , feather ruffling, and necrotic foci in liver at PM are common.
Cause diarrhea and weight loss, leads to emaciation and death. Some die suddenly of septicemia. Bc rapid onset, sometimes cant treat
Y. enterocolitica is primarily a human enteric pathogen, wild and domestic animals act as reservoirs. Pig is natural revisor for serotype 03 biotype 4- humans
Y diagnosis
Histo exam of intestinal lesion
Culture
Plate on Mac for growth at 37 or 22- non lac fermenting
Cold enrichment (grow at 4 for a few days, bc most cant survive on that)
Serotyping
Plague
Caused by y. pestis
3 biotypes
Zoonotic infection transmitted by rodents transferred by fleas (Urban and Sylvatic cycle)
Endemic to Africa, Asia, and parts of USA
Some sp are more susceptible then others, prairie dog is really susceptible
Y. pestis clinical infection
can infect both dogs and cats in endemic areas, but cats are particularly susceptible bc eat rodents
Cats with pneumonic plague are a source of human infection through aerosol generation and should be euth. Human infection can be acquired through cat scratches, bits, and fleas from infected cats
Plague syntromes in man
Bubonic- fever, painful lymphadenopathy (LN swell and rupture pus)
Sypticaemic- fever, hypotension (from pus to blood) w/wo bubo
Pneumonic- cough, haemoptysis, w/wo bubo (blood to lung)
Meningitis- fever, nuchal rigidity usually w/ bubo
Virulence factors of y. pestis
F1 antigen (Fraction 1)- plasmid encoded capsule to prevent opsinisation
HPI- Fe acquisition
Ymt- plasmid pro, phospolipase D required for survival in flea midgut
Hms locus- required for efficient transmission to sub q site. With out, will replicate in midgut, but cant lodge in proventriculus for transmission
Pla- plasmid encoded and essential to disseminate from sub q site to LN or bloodstream
Y. pestis diagnosis
Specimens sent to specialised labs Giemsa stain- bipolar rods Culture DFA test Passive haemagglutination on paired samples from infected cats. Rising titer suggests active infection
Y pestis treatment and control
Cats suspected to be positive should be kept in isolation
IV tetracycline or chloramphenicol for bubonic
In endemic areas, dogs/cats should be routienly treated for fleas
Rodent control
Effective human and animal based surveillance avoid sick/dead animals Avoid endemic/outbreak areas Vaccination (military) Insect repellents Isolate human cases/contact
Pseudomonas aeruginosa and Burkholderia sp
Gram neg rods
Obligate aerobes
Oxidise carbs (non fermentative), but Oxidase and catalase positive
Motile by one or more polar flagella ( B. mallei no motile)
Grow well on mac
Pseudomonas aeruginosa
Opportunistic pathogen- Mink seem to be very suceptable
Causes mastitis in cow- associated with contaminated water for washing mam glands, and intrammamary antibiotic insertion
Fleece rot in sheep- associated with prolonged rainfall, causing suppurative dermatitis and pyocyanin pigment production which discolors the wool
Dog/cat olitis externa
Captive reptiles- necrotic stomatitis (severe mouth infection)
Environmental organism and found on skin, mucous membs, and feces
