Gram-Negative Bacilli, Non-spore forming Flashcards
All members are non-encapsulated except for
Klebsiella and Enterobacter
Most of them are present in the intestinal tract as commensal microbiota except for
Plesiomonas, Salmonella, Shigella, and Yersinia
Some organisms like? may grow at 1C to 5C
Serratia and Yersinia
Biochemical test: (+) catalase; (-) oxidase except for
Plesiomonas shigellosis
They are not present as commensal microbiota of the human GIT
Overt/True Pathogens
They are acquired through ingestion of contaminated food or water
Overt/True Pathogens
Their presence in specimens is considered as very significant
e: E.coli, Citrobacter, Enterobacter, Klebsiella, Proteus, and Serratia
2.
Example of Overt/True Pathogen
Salmonella, Shigella, and Yersinia pestis
They are part of the intestinal microbiota of both humans and animals
They generally do not initiate disease in healthy, uncompromised human host
Oppurtunistic Pathogens
They may produce serious extraintestinal infection outside their normal body sites
They produce significant virulent factors
Opportunistic pathogens
Examples of Oppurtunistic pathogens are
: E.coli, Citrobacter, Enterobacter, Klebsiella, Proteus, and Serratia
heat-stable; located in the cell wall; used for E.coli and Shigella serotyping
Somatic O antigen
- heat-labile; found in the flagellum; used for Salmonella serotyping
Flagellar H antigen-
-heat-labile polysaccharide; found as K1 antigen of E.coli and Vi antigen of
S. entrica subsp. enterica serotype typh
Capsular K antigen
It may inhabit the female genital tract, although it is a microbiota of the large intestine
Escherichia coli
It is a primary indicator of fecal contamination in water purification
It is the leading cause of nosocomial urinary tract infection
Escherichia coli
It has both the sex pili and adhesive fimbrae
Escherichia coli
EMB-Colonies exhibit a greenish metallic sheen
Escherichia coli
IMViC- ++/–
TSIA reaction: A/A (acidic slant/acidic butt), (+) gas, (-) hydrogen sulfide or H2S
Escherichia coli
Pili that permit gastrointestinal colonization, Heat- Labile and Heat-stable enterotoxins that mediate secretion of water and electrolytles into the bowel lumen
Enterotoxigenic E.coli
Virulence factors uncertainm but organism invades enterocytes lining the large intestine in a manner nearly identical to shigella
Enteroinvasice E.coli
Bundle-forming pilus, intimin and other factors that mediate organism attachment to mucosal cells of the small bowel, resulting in changes in cell surface
Enteropathogenic E.coli
Toxin similar to Shiga toxin produced by Shighella dysenteriae. Most frequently associates with certain serotypes such as E.coli O157:H7
Enterohemorrhagic E.coli
Probably involves bindin by Pili, ST-like and hemolysin-like toxins, actual pathogenic mechanism is unkown
Enteroaggregative E.coli
It is formerly called E.coli atypical or enteric group II
It has been isolated from CSF, wounds, blood
Escherichia hermanii
Culture: Colonies have yellow pigmentation
Escherichia hermanii
The species of this genus are usually found in the GIT of humans and animals
Culture: MAC-Colonies exhibit pink color
Klebsiella
It is the causative agent of community-acquired pneumonia; afflicted patients cough up “currant
jelly-like” sputum
Klebsiella pneumonia subsp. Pneumonia (Friedlander‘s bacillus)
t is the frequent cause of lower respiratory tract infections among hospitalized patients and in
immunocompromised hosts such as newborns, elderly patients, and patients on respirators
Klebsiella pneumonia subsp. Pneumonia (Friedlander‘s bacillus)
Virulence factor: Polysaccharide capsule
Culture: MAC-colonies exhibit a pink color and are mucoid (LF)
Klebsiella pneumonia subsp. Pneumonia (Friedlander‘s bacillus)
Differential test for Klebsielle pneumoniae
String Test
Neufeld-Quellung test is for?
Presence of Capsule
IMViC reactions: –/++
It is the causative agent of community-acquired pneumonia; afflicted patients cough up ―currant
jelly-like‖ sputum
Klebsiella pneumonia subsp. Pneumonia (Friedlander‘s bacillus)
Enterobacter Lysine decarboxylase test: Positive except for?
Enterobacter cloacae and Enterobacter gergoviae
IMViC reaction: –/++
TSIA reaction: A/A. (+) gas, (-) H2S
Enterobacter
It is found in respiratory samples and is rarely isolated from blood cultures
Enterobacter gergoviae
It has been isolated with osteomyelitis following traumatic wounds
Enterobacter cancerogenus (formerly E. taylorae)
It is formerely known as Enterobacter sakazakii
Cronobacter sakazakii
It is found as a contaminant of powdered infant formula
Cronobacter sakazakii
It is isolated from individuals with brain abscess, and respiratory and wound infcetions
Cronobacter sakazakii
Culture:
o MAC-Colonies exhibit a pink color
o BHIA-Colonies exhibit a yellow pigmentation
o IMViC reaction:–/++
o TSIA reaction: A/A, (+) gas, (-) H2S
Cronobacter sakazakii
It is formerly known as Enterobacter agglomerans
It causes nosocomial outbreaks of septicemia due to contamination of IV fluids
Pantoea agglomerans
It causes nosocomial outbreaks of septicemia due to contamination of IV fluids
Pantoea agglomerans
IMViC reaction: - v/+ v
TSIA reaction: K/A, (-) gas, (-) H2S
Serratia
The species in this group are opportunistic pathogens that are usually associated with
nosocomial outbreaks
The species are resistant to a wide range of antibiotics
Serratia
Culture: MAC- Colonies are clear and colorless. Some strains may show a slow or late lactose
fermentation
Biochemical test: (+) DNAse, gelatinase, lipase, and ONPG
serratia
IMViC reaction: –/++
TSIA reaction: K/A, (+) gas, (-) H2S
Serratia
has a musty and pungent odor or a ―”rotten potato-like” odor
Serratia odorifera
ferments arabinose and exhibits growth in a culture medium with KCN
Serratia liquefaciens