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
It causes bacteremic outbreaks in nurseries, cardiac surgery units, and burn units
A few strains of this species are late lactose fermenters
Biochemical test: (+) urease, gelatinase and ONPG; (-) arabinose fermentation
Serratia marcescens
The species of this genus are isolated from urine, wound, and ear infections
Proteus
The species can infect the proximal kidney tubules and can cause acute glomerulonephritis,
particularly in patients with UTI in catheterixation
Proteus
The species are rapid urease producers; the urease that they produce splits urea in urine,
raises urine pH, and encourages renal stone formation
Proteus
Human pathogens of Proteus
P. mirabilis and P. vulgaris
Common isolate of proteus
P. mirabilis
Culture: MAC-Colonies are clear and colorless; exhibit a “swarming phenomenon”; and have a
“burnt-chocolate” or “burnt-gunpowder” odor
Proteus
IMVic: -+/vv
K/A, (+) gas, (+) H2S
P. mirabilis
IMVic:++/-v
K/A, (+/-) gas, (+) H2S
P. vulgaris
Lysine iron agar reaction: R/A
Proteus
The species of this genus are the cause of nosocomial outbreaks involving burn units
Culture: MAC-Colonies are clear and colorless
Providencia
IMViC reactions: ++/-+
LIA reaction: R/A
TSIA reaction: k/A, (-) gas, (-) H2S
Providencia
It is a pathogen of the urinary tract
It also causes diarrheal disease among travelers
It is mostly resistant to antimicrobial agents
Providencia rettgeri
It is found in cosocomial outbreaks in burn units
It is also mostly resistant to antimicrobial agents
Providencia stuartii
It is most commonly found in the feces of children with diarrhea
Providencia alcalifaciens
The species of this genus have the same biochemical reaction as those of P. vulgaris, except
that the latter is citrate-negative
Morganella
PAD test: Positive
IMViC reaction: ++/- -
LIA reaction: R/A
TSIA reaction: K/A, (+) gas, (-) H2S
Morganella
The species of this genus produce colonies in MAC agar that are similar to those of E.coli and
have a biochemical resemblance to those of Salmonella
Citrobacter
IMViC reaction:C. koseri
+ + - +
IMViC reaction: C. freundii
- +
It can be isolated in diarrheal stool cutures
Citrobacter freundii
It produces group 1 cephalosporinase
Citrobacter freundii
It causes outbreaks of neonatal meningitis and brain abscess in nursery units
Citrobacter koseri (formerly C. diversus)
The species of this genus are the most pathogenic enterobacteria that cause enteric fever and
acute gastroenteritis to humans
Salmonella
They are not part of the large intestine microbiota
They inhabit the GIT of humans and animals
Salmonella
Mode of acquisition: Ingestion of contaminated animal food products or improperly cooked
poultry, milk, eggs, and dairy; and direct human contact
Salmonella
Virulence factors of Salmonella
: Fimbrae and enterotoxin
Antigenic structure of Salmonella:
for serologic grouping
Somatic O and flagellar H
Antigenic structure of Salmonella:
antiphagocytic
Vi antigen
The main etiologic agent of enteric fever is
Salmonella serotype typhi
The etiologic agents of paratyphoid fever are
Salmonella serotype Paratyphi A, B, and C, and
Salmonella serotype Choleraesuis
Fever that is from Ricketssia, lice, mice, ticks, and flea
Typhus Fever
Fever that is from Salmonella typhi, and food poisoning
Typhoid Fever
It is named after the town of Bongor in Chad, Africa where it was isolated from a host lizard in
1966
Salmonella bongori
It can also be isolated from other cold-blooded animals aside from lizards
Salmonella bongori
All species of Salmonella are motile except for
Salmonella serotype Pullorum and Salmonella serotype
Gallinarum
All species of Salmonella produce gas except for
Salmonella serotype Gallinarum and Salmonella serotype
Typhi
All species of Salmonella produce H2S except
Salmonella serotype Paratyphi A
It is one of the most common forms of poisoning
Gastoenteritis
Gastroenteritis is most commonly cause by what type of Salmonella?
Salmonella enterica subsp. enterica
Salmonella outbreak in the US in 2009 came from contaminated
peanut butter crackers
Salmonella serotype Typhimurium
Sources of infection: Poultry products, milk, and handling of pets
Gastroenteritis
Infective dose of gastroenteritis
10^6 bacteria
It is a febrile disease that develops from eating contaminated food prepared by infected
individuals or carriers
Enteric fever (Typhoid fever)
Causative agent of Enteric Fever
Salmonella enterica subsp. enterica serotype typhi
Causes of outbreaks: Improper sewage disposal, poor sanitation, and lack of clean water
source
Enteric fever (Typhoid fever)
Symptoms:Malaise, anorexia, myalgia, and severe frontal headache
Enteric fever (Typhoid fever)
Complication: Necrosis in the gallbladder and Peyer‘s patches
Enteric fever (Typhoid fever)
The hallmark of its infection is the appearance of “rose spots” during the second week of fever
Enteric fever (Typhoid fever)
The site of long-term carriage of enteric fever
Gall Bladder
It occurs with and withour extraintestinal infection that is caused by non-typhoidal Salmonella
species
Bacteremia
It is characterized by prolonged fever and intermittent bacteremia.
Bacteremia
causative agents of Bacterimia
Salmonella serotype typhimurium, salmonella serotype paratyphi and salmonella serotype choleraesius
Specimens for Salmonella Identification:
First week of infection
Blood
Specimens for Salmonella Identification:
Second to third week of infection
Stool
Specimens for Salmonella Identification:
Third week of infection
Urine
The species of this genus are closely related to those of Escherichia
Shigella
These species are non-motile, intracellular pathogens that multiply within the cells of the
intestinal epithelium
Shigella
Most of the species can cause bacillary dysentery
Shigella
The most virulent specie of shigella is
Shigella dysenteriae
Shigella specie that causes gay bowel syndrome
Shigella flexneri
Antigenic structure of Shigella
Somatic O
All species of shigella does not produce gas from glucose except for?
Shigelle flexneri
All species are mannitol fermenters except for?
Shigella dysenteriae
True or False: All species of Shigella does not decarboxylate lysine?
True
All species of Shigella do not decarboxylate ornithine except for
Shigella sonnei
It is a specie of shigella that is a late lactose fermenter and has positive reaction with ONPG test
Shigella sonnei
It is the most virulent of the shigella specie and causes bacillary dysentery
Shigella dysenteriae
Virulence factor of Shigella dysenteriae
Shiga toxin
The infection from this shigella is self-limiting, and usually characterized by fever and watery
diarrheaig
Shigella sonnei
Shigella that has one serotype as opposed to the other species, which have several serotypes
Shigella sonnei
It is an infection that is most commonly caused by S. dysenteriae type I
Bacillary dysentery
It is highly communicable because of the low infective dose that is required to produce the
disease
Bacillary dysentery
s characterized by acute inflammatory colitis and bloody diarrhea
Bacillary dysentery
In young children, rectal prolapse occurs due to the excessive straining
Bacillary dysentery
Complications: Ileus, seizure, and hemolytic uremic syndrome
Bacillary dysentery