Gram - negative bacilli, non spore forming part 2 Flashcards
It is also known as the ―”plague bacillus”
Yersinia pestis
It is a class A bioterrorism agent
Yersinia pestis
It is the only enterobacterium that is transmitted to humans through the bite of an infected flea
yersinia pestis
It is the causative agent of the bubonic plague
yersinia pestis
It can be isolated on a routine culture media, and grows best at 25C to 30C
Yersinia pestis
Vector of Yersinia pestis
Xenopsylla cheopis (oriental rat flea)
Its reservoir is the rats
Yersinia pestis
Virulence factors of Yersinia pestis
Endotoxin, coagulase, and fibrinolysin
Microscopy: Short, plump rod with a bipolar body or a ―”closed safety pin” appearance
Yersinia pestis
Broth- Colonies have a ―stalactite-shaped‖ pattern
Yersinia pestis
It is a disease of the rodents that is caused by Yersinia pestis and is transmitted to humans
through flea bites
Plague
Humans may also acquire it by ingestion of contaminated animal tissues and inhalation of
contaminated airborne droplets
Plague
Once plague is inside the human body, the bacteria multiply in the?
blood and lymph
There are 2 forms of plague:
It results from the bite of infected flea
Bubonic plague
There are 2 forms of plague:
It is associated with high fever and painful inflammatory swelling of the axilla and
groin
Bubonic plague
There are 2 forms of plague:
It is acquired by close contact with infected individuals
Pulmonary plague
There are 2 forms of plague:
It occurs secondarily to bubonic plague
Pulmonary plague
It is the most commonly isolated species of Yersinia
Yersinia enterocolitica
It is the causative agent of enterocolitis or waterborne gastroenteritis
Yersinia enterocolitica
It is motile in SIM at 22C but not at 35C
Yersinia enterocolitica
It has been isolated from contaminated packed RBC units, and is thus considered as a blood
transfusion hazard
Yersinia enterocolitica
It has the ability to survive in cold temperatures
Yersinia enterocolitica
Its reservoirs are swines, dogs, cats, rabbits, and cows
Yersinia enterocolitica
Related infections: Appendicitis-like syndrome, arthritis, and erythema nodosum
Yersinia enterocolitica
Selective medium: Cefsulodin-irgasan-novobiocin (CIN) aga
Yersinia enterocolitica
Microscopy: Coccobacilli with bipolar bodies
Yersinia enterocolitica
CIN- Colonies exhibit a ―”bull‘s eye” appearance or dark red or burgundy centers with
transparent borders at 48 hours of incubation
Yersinia enterocolitica
It is a pathogen of the rodents, particularly guinea pigs
Yersinia pseudotuberculosis
It is motile in SIM at 18C to 25C but not at 35C
Yersinia pseudotuberculosis
Its reservoirs are farm and domestic animals (usually birds)
Yersinia pseudotuberculosis
It is the only oxidase-positive member of the Enterobacteriaceae
Plesiomonas shigelloides
Its motility is attributed to its polar flagella
Plesiomonas shigelloides
It has been associated with HIV-positive individuals with inflammatory bowel disease
Plesiomonas shigelloides
It has been associated with HIV-positive individuals with inflammatory bowel disease
Plesiomonas shigelloides
Mode of acquisition: Ingestion of undercooked seafood and contaminated water
Plesiomonas shigelloides
Vibriostatic test: O/129: Sensitive
Plesiomonas shigelloides
Microscopy: Straight bacilli which can occur singly, in pairs, in short chains, or filamentous
Plesiomonas shigelloides
o Inositol-brilliant green-bile salt agar: Colonies exhibit white or green to pink color for
other enterics
Plesiomonas shigelloides
The use of?? enhances the recovery of plesiomonads from
specimen
inositol-brilliant green bile agar
Decarboxylase test: Positive trio decarboxylase test
Plesiomonas shigelloides
The species of this genus have been isolated from cold-blooded and warm-blooded animals
Edwardsiella
Species of Edwarsiella
Edwardsiella tarda
stain that can be used to obseve the bipolar bodies of Y. pestis
Wayson stain
Optimal temperature of growth of Serratia and Yersinia?
1 to 5 degrees celsius
Optimal temperature of growth of Escherichia coli
40 degrees celsius
Rapid lactose fermenters:
Enterobacter, Eschericihia coli, Klebsiella
Late lactose fermenters:
Citrobacter freundii, Shigella sonnei, and Serratia
Non-lactose fermenters:
Citrobacter koseri, Edwardsiella, Morganella, Proteus,
Providencia, Slmonella, Shigella, and Yersinia
It contains bile salt, bromthymol-blue dye, alicin, lactose, and sucrose
The bile and dye inhibit the growth of other Gram-negative bacilli in the GIT and
promote the isolation of Salmonella and Shigella
Hektoen enteric agar (HEA)
pH indicator of hektoen enteric Agar
Bromthymol blue
H2S indicator of Hektoen Enteric Agar
Ferric ammonium citrate
Growth on HEA
Lactose Fermenter?
colonies exhibit a yellow color
Growth on HEA
Non-lactose fermenter
colonies exhibit a blue-green color
Growth on HEA
Non-enteric pathogens
-Colonies exhibit an orange to pinkish orange color
It is used for the isolation of Salmonella and Shigella species from heavily
contaminated specimens such as stool
Xylose-lysine deoxycholate (XLD) agar
pH indicator of XLD agar
Phenol red
H2S indicator of XLD agar
sodium thiosulfate and ferric ammonium sulfate
Growth on XLD agar shigella?
colonies exhibit a pink to red color
Growth on XLD agar salmonella?
colonies exhibit a pink to red color with black centers
Growth on XLD agar other enterobacteriaciae?
Colonies exhibit a yellow to red color
pH indicator of EMB?
eosin and methylene blue
result of EMB
Lactose fermenter?
Colonies of Escherichia coli exhibit a greenish metallic sheen while those of other exhibit purple color
Result of EMB Other coliforms
colonies exhibit a pink color
Salmonella-shigella agar contents that inhibits gram positive bacteria and some lactose fermenters that are found in stool specimens
Bile salts and Brilliant green dye
pH indicator of SSA
Neutral red
H2S indicator of SSA
Sodium thiosulfate and ferric ammonium citrate
Salmonella serotypin
Heat Labile antigen
Flagellar antigen
H antigen
Salmonella serotype typhi also produce what
Heat labile capsular polysaccharide V-antigen and carries the D serogroup
E. coli serotype that are most frequently associated with infantile diarrhea
E.coli O55, O111, O127
Salmonella-Shigella agar (SSA) - Colonies are pink or colorless with black centers
Salmonella
Salmonella-Shigella agar (SSA)-Colonies are pink or colorless without black centers
shigella
Salmonella-Shigella agar (SSA);H2S indicator
Sodium thiosulfate and ferric ammonium citrate