LECT | ENTEROBACTERIACEAE Flashcards
- Gram negative bacilli and coccobacilli
- Oxidase negative
- Glucose fermenter
- Reduce nitrate to nitrite
- Motile at body temperatures
Enterobacteriacaea
members of Enterobacteriacaea family produce large, moist, gray colonies on what media
nonselective media
- Gram negative bacilli and coccobacilli
- Oxidase negative
- Glucose fermenter
- Reduce nitrate to nitrite
Enterobacteriacaea general characteristics
Enterobacteriaceae reside in
- gastrointestinal
- microbiota if confined to their natural environment (Salmonella, Shigella, and Yersinia)
Enterobacteriaceae may be divided into two broad categories:
- opportunistic pathogens
- primary pathogens.
often a part of the usual intestinal microbiota of both humans and animals
opportunistic pathogens
bacterias under UTI
- E. coli
- Proteus mirabilis
- Klebsiella penumoniae
bacterias under PNEUMONIA
Klebsiella pneumoniae
bacterias under BACTEREMIAS
- E. coli
- Proteus mirabilis
- Kiebsiella pneumoniae
bacterias under HOSPITAL ACQUIRED INFECTIONS
(Antiobiotic resistant genera)
- Citrobacter
- Enterobacter
- Serratia
bacterias under DIARRHEA
- Shigella spp.
- Salmonella spp.
- E,coli
(enterohemorrhagic [Shiga toxin
producing] enterotoxigenic, enteroinvasive, enteropathogenic, enteroadherent - Yersinia spp.
somatic antigen; — this is a heat- stable antigen located on the cell wall
O antigen
flagellar antigen; this is a heat- labile antigen found on the surface of flagella, structures responsible for motility
H antigen
capsular antigen; this is a heat- labile polysaccharide found only in certain encapsulated species
K antigen
capsular antigen of E coli
K1 antigen
capsular antigen of Salmonella enterica subsp. enterica serotype Typhi
Vi antigen
Leading cause of community acquired urinary tract infections
E. coli
Primary marker of E. coli
fecal contamination in water quality testing
Major cause of E. coli-associated community- acquired urinary tract infections
Major cause of E. coli-associated community- acquired urinary tract infections
E. coli strains that cause UTIs usually originate in the
large intestine as resident biota
E. coli strains that cause acute pyelonephritishave been shown to be the
dominant resident E. coli in the colon.
primary virulence factor (ability of E. coli to cause UTIs)
production of pili
pili allows uropathogenic strains to
adhere to epithelial cells and not be washed out with urine flow
other virulence factors contributing to the of uropathogenic E. coli characterized as hemolysins
Cytolysins
hemolysins; kill immune effector cells and inhibit phagocytosis and chemotaxis of certain white blood cells.
Cytolysins
allows the bacterial cell to chelate iron; free iron is generally unavailable within the host for use by bacteria.
Aerobactin
- Neonatal meningitis
- Test positive for the K1 antigen
Meninges/sepsis associated-E coli (MNEC)
Meninges/sepsis associated-E coli (MNEC) spread to the meninges from a blood infection and gain access to the (?), VIA (?)
central nervous system | via membrane-bound vacuoles
once Meninges/sepsis associated-E coli (MNEC) is inside the cell, it prevents
lysosomal fusion and gain access to the central nervous system.
five major categories of diarrheagenic E. coli:
- enterotoxigenic Escherichia coli (ETEC)
- enteroinvasive Escherichia coli (EIEC)
- enteropathogenic Escherichia coli (EPEC)
- enterohemorrhagic Escherichia coli (EHEC)
- enteroadherent Escherichia coli (EAEC)
- produces a heat-labile enterotoxin (LT) and a heat-stable enterotoxin (ST)
- associated with cases of traveler’s diarrhea.
enterotoxigenic Escherichia coli (ETEC)
mild, watery diarrhea; no blood nor leukocytes and abdominal cramping. usually with no vomiting or fever
traveler’s diarrhea
- Watery to bloody diarrhea–similar to Shigella
- RBC +, WBC+
enteroinvasive Escherichia coli
EIEC may produce a watery to bloody diarrhea as a result of
direct invasion of the epithelial cells of the colon similar to Shigella spp.
produce dysentery with direct penetration, invasion, and destruction of the intestinal mucosa.
EIEC
- attachment and effacement lesion in the
colon. - Prolonged (chronic), non bloody diarrhea;
vomiting; and fever, typically in infants or children
EPEC
- pediatric diarrhea, foodborne outbreaks, and diarrhea in HIV-infected and AIDS patients
- Stool are not bloody and do not contain
white blood cells - AggR gene
EAEC
causes stool to contains large amounts of mucus, but apparent blood is not present
EPEC
- Verocytotoxin-producing E. coli (VTEC)
- Hemorrhagic colitis.
- Hemolytic uremic syndrome (HUS) -
Escherichia coli O157:H7 & 0157:NM (nonmotile)
higa toxin-producing E. coli (STEC)
- The classification as aggregative results from the control of virulence genes associated with a global aggregative regulator gene.
- responsible for cellular adherence
AggR
bacteria causing Hemolytic uremic syndrome (HUS)
Escherichia coli O157:H7 & 0157:NM (nonmotile)
characterized by a hemolytic anemia and low platelet count, often results in kidney failure and death
Hemolytic uremic syndrome (HUS)
component of the lipopolysaccharide of the outer membrane
O antigen (156 serotypes)
specific flagellin associated with the STEC.
H antigen (56 serotypes)
carry a heat-labile cytotoxin, which has been isolated from patients who have developed a self- limiting antibiotic associated hemorrhagic colitis.
K. oxytoca
liver abscesses, pneumonia, septicemia, and urinary tract infections
Klebsiella spp
community-acquired pyogenic liver abscesses; hypervirulent phenotype(hvKP)
K.pneumoniae
have the ability to spread in healthy patients because of an intrinsic resistance to serum complement and the bactericidal effects of neutrophils
hvKP clinical variants
resistant to ampicillin
K. pneumoniae
demonstrate multiple antibiotic resistance patterns from the acquisition of multidrug-resistant plasmids with enzymes
K. pneumoniae
K. pneumoniae demonstrate multiple antibiotic resistance patterns from the acquisition of multidrug-resistant plasmids such as:
- carbapenemase
- ephalosporinases
containing Klebsiella organisms are increasingly isolated from community-acquired pyogenic liver abscesses worldwide and demonstrate a hypervirulent (hypermucoviscous) phenotype (hvKP).
K1 capsular clonal complex (CC23k1)
associated with severe pneumonia and bloodstream infections.
K1 capsular clonal complex (CC82k1)
- Visualized in scrapings of lesions stained with Wright or Giemsa stain
- Agent of Donovanosis or granuloma inguinale
Klebsiella granulomatis
Groups of organisms are seen within mononuclear endothelial cells
Klebsiella granulomatis
his pathognomonic entity is known as a Donovan body
Klebsiella granulomatis
Klebsiella granulomatis stains as a
blue rod with promi nent polar granules, giving rise to a “safety pin” appearance, surrounded by a large, pink capsule.
- One of the most commonly isolated health care–associated infections
- Associated with contaminated medical devices such as respirators and other medical instrumentation
- Organisms are also ingested from water, vegetable, and food products
Enterobacter spp
- Dysentery (acute inflammatory colitis & bloody diarrhea characterized by cramps, tenesmus, bloody & mucoid stools)
- Shigella sonnei may produce watery diarrhea
Shigello spp
acute inflammatory colitis & bloody diarrhea characterized by cramps, tenesmus, bloody & mucoid stools
Dysentery
- Infections are associated with consumption of contaminated food such as meat and dairy products
- Most infections with H. alvei are identified in patients with severe underlying disease (e.g., malignancies) or after surgery or trauma
HAFNIA ALVEI
- Often associated with stool specimens from patients with symptoms of diarrhea
MORGANELLA SPP.
- Caused gastroenteritis, most commonly in children
- An emerging enteric pathogen associated with food-and water-borne illness
Pleasiomonas shigelloides
a fresh water inhabitant that is trans mitted to humans by ingestion of contaminated water or by exposure of disrupted skin and mucosal surfaces
Plesiomonas shigelloides
- Often associated with urinary tract infections; however, isolated from wounds and ears.
- Associated with diarrhea and sepsis
Proteus spp.
easily identified by their classic “swarming”
appearance on culture media.
Proteus spp.
- Known for colonization and the cause of pathogenic infection in health care settings
- AmpC beta-lactamase
Serratia marcescens
resistant to ampicillin and first-generation ceph alosporins because of the presence of an inducible, chromosomal AmpC beta-lactamase.
Serratia spp.
- Salmonella serotype typhi: typhoid fever
- Salmonella serotype enteritidis: associated with infections acquired from the ingestion of eggs or chicken
Salmonella
acultative anaerobic, motile, gram-negative rods commonly isolated from the intestines of humans and animals.
Salmonella (all serotypes)
Serotypes are differentiated based on the characterization of
- heat-stable O antigen, included in the LPS
2, heat-labile H antigen flagellar protein - heat-labile Vi antigen, capsular polysaccharide.
Typhi associated with a severe disease is called
typhoid fever
the patient may present with a rash and appear confused
typhoid fever
The disease is transmitted person-to-person or through contaminated food and water.
typhoid fever
Diarrhea and vomiting are not associated with
typhoid fever.
- Serotyping is based on the somatic LPS O antigen
- Shigellosis –> dysentery with stools that contain blood or mucus
- S.dysenteriae 1: most severe form
SHIGELLA SPP.
produces the most severe forms of illness and may lead to hemolytic uremic syndrome (HUS)
S. dysenteriae 1
- most commonly transmitted by the bite of an infected flea resulting in bubonic plague.
- handling infected animals, inhaling infectious droplets, and ingestion of undercooked meat have also resulted in infections.
- Human-to-human transmission is possible with the pneumonic (respiratory) form of disease.
Y. pestis
found in the gastrointestinal tract of swine,
rodents, and dogs
Y.enterocolitica
found in a variety of wild and domesticated animals including rodents, birds, and rabbits
Y. pseudotuberculosis
