Lesson 11 Flashcards
All ferment glucose
ENTEROBACTERICEAE
WHAT ARE THE TWO CATEGORIES OF MEMBERS OF FAMILY
ENTEROBACTERIACEAE?
- OPPORTUNISTIC PATHOGENS
- PRIMARY INTESTINAL PATHOGENS
WHAT ARE THE OPPORTUNISTIC PATHOGENS OF FAMILY ENTEROBACTERIACEAE?
Citrobacter
Enterobacter
Edwardsiella
Hafnia
Klebsiella
Proteus
Providencia
Serratia
Morganella
Ewingella
Plesiomonas
Often part of the normal intestinal flora
May produce serious extraintestinal opportunistic
infections
OPPORTUNISTIC PATHOGENS
WHAT ARE THE PRIMARY INTESTINAL PATHOGENS OF THE FAMILY ENTEROBACTERIACEAE?
Salmonella
Shigella
Yersinia
True pathogens / Overt pathogens
Not part of the normal intestinal flora
PRIMARY INTESTINAL PATHOGENS
It is a normal bowel inhabitant but its pathogenic
classification is somewhere between overt pathogens and
opportunistic pathogens
Escherichia coli
ENTEROBACTERICEAE: VIRULENCE AND ANTIGENIC
FACTORS
o Ability to colonize, adhere and invade tissues
o Production of toxins
o Presence of plasmids that mediate resistance to
antimicrobials
What are the antigens used for identifying different serological
groups of ENTEROBACTERICEAE?
- Somatic Antigen (O Ag)
- Flagellar Antigen (H Ag)
- Capsular Antigen (K Ag)
What type of atigen is located in the cell wall
and heat stable?
Somatic Antigen (O Ag)
This type of antigen is Heat labile
only
Flagellar Antigen (H Ag)
This type of Antigen is heat labile, Capsule K1 Antigen of E. coli
and Vi Antigen of Salmonella typhi
Capsular Antigen (K Ag)
This type of agar can be used
when suspecting enteric pathogens, it is preferred to use selective and differential media
Chocolate Agar Plate (CAP) or Blood Agar Plate (BAP)
On BAP, colonies may be haemolytic. It is usually what type of hemolytic?
β or non haemolytic
WHAT ARE THE SELECTIVE AND DIFFERENTIAL MEDIA FOR ISOLATION OF
ENTEROBACTERIACEAE?
- MCA
o Mac Conkey Agar - EMB
o Eosin Methylene Blue Agar - XLD
o Xylose Lysine Desoxycholate Agar - SSA
o Salmonella-Shigella Agar - HEA
o Hektoen-Enteric Agar - Sel-F Broth
° Selenite F Broth
WHAT ARE THE BIOCHEMICAL TESTS OF ENTEROBACTERICEAE?
▪ TSI / KIA
▪ Indole
▪ Citrate Utilization
▪ Urease Production
▪ Motility Test
▪ Decarboxylase Test
▪ ONPG
▪ LIA
▪ MR-VP Test
▪ PAD
▪ Nitrate Reduction Test
o Inhabitants of the intestinal tract
o Most ferment lactose
o Colonies on MCA resembles those of E. coli
GENUS CITROBACTER
GIVE ME THE GENUS AND SPECIES OF THE CITROBACTER
Citrobacter freundii
Citrobacter diversus
Citrobacter amaloniticus
Citrobacter koseri
Citrobacter braakii
What are the associated with infectious diseases acquired in hospital settings of Citrobacter freundii?
➢ UTI
➢ Pneumonia
➢ Intraabdominal abscess
➢ Endocarditis
➢ Septicemia
➢ Meningitis
➢ Brain abscess and neurologic complications
Colonial morphology may be easily mistaken for that of Salmonella
May harbor inducible AmpC genes that encode
resistance to ampicillin and first generation
cephalosporins
Citrobacter freundii
Causes nursery outbreaks of neonatal meningitis and
brain abscess
Citrobacter diversus
Frequently found in feces (not a causative agent of
diarrhea)
and Have been isolated from blood and wound
Citrobacter amalonaticus
Formerly Aerobacter
Frequently associated with health-care associated
infections
May harbour plasmids that encode multiple antibiotic
resistance genes
GENUS ENTEROBACTER
A /A
Lysine (-)
Ornithine (+)
Motility (+)
IMVC: –+ +
Enterobacter cloacae
Formerly Enterobacter agglomerans
Associated with outbreak of septicemia due to
contaminated IV fluids
Pantoea agglomerans
Formerly Enterobacter sakazakii
Pathogen associated with bacteremia, meningitis and
necrotizing colitis in neonates
Isolated from brain abscesses, respiratory and wound
infections
Cronobacter sakazakii
Found in respiratory samples
Rarely isolated from blood cultures
Enterobacter gergoviae
Now called, Klebsiella aerogenes
Lysine (+)
Enterobacter aerogenes
Isolated from blood, wound, sputum
Enterobacter hormaechei
GIVE ME THE GENUS AND SPECIES OF THE ENTEROBACTER
Enterobacter cloacae
Pantoea agglomerans
Cronobacter sakazakii
Enterobacter gergoviae
Enterobacter aerogenes
Enterobacter hormaechei
Enterobacter taylorae
Enterobacter amnigenus
Enterobacter asburiae
Enterobacter intermedius
GIVE ME THE GENUS AND SPECIES OF THE EDWARDSIELLA
Edwardsiella tarda
Edwardsiella hoshinae
GIVE ME THE GENUS AND SPECIES OF THE HAFNIA
Hafnia alvei
GIVE ME THE GENUS AND SPECIES OF THE KLEBSIELLA
Klebsiella pneumoniae
Klebsiella oxytoca
Klebsiella terrigena
Klebsiella group 47
Give me the subspecies of Klebsiella pneumoniae
Klebsiella pneumoniae ssp. ozaenae
Klebsiella pneumoniae ssp. pneumoniae
Klebsiella pneumoniae ssp. rhinoscleromatis
Give me the 2 Klebsiella group 47
Klebsiella ornithinolytica
Klebsiella planticola
GIVE ME THE GENUS AND SPECIES OF THE PROTEUS
Proteus vulgaris
Proteus mirabilis
Proteus penneri
GIVE ME THE GENUS AND SPECIES OF THE PROVIDENCIA
Providencia rettgeri
Providencia stuartii
Providencia alcalifaciens
Providencia rustigianii
GIVE ME THE GENUS AND SPECIES OF THE SERRATIA
Serratia marcescens
Serratia rubidea
Serratia liquefaciens
Serratia odorifera
Serratia ficaria
Serratia grimesii
Serratia proteamaculans
Serratia fonticola
Serratia plymuthica
GIVE ME THE GENUS AND SPECIES OF THE MORGANELLA
Morganella morganii
Morganella psychrotolerans
GIVE ME THE GENUS AND SPECIES OF THE EWINGELLA
Ewingella americana
GIVE ME THE GENUS AND SPECIES OF THE PLESIOMONAS
Plesiomonas shigelloides
GIVE ME THE GENUS AND SPECIES OF THE SALMONELLA
Salmonella typhosa/typhi
Salmonella cholerasuis
Salmonella enteritidis
Salmonella enterica
Salmonella bongori
GIVE ME THE GENUS AND SPECIES OF THE SHIGELLA
Shigella dysenteriae
Shigella flexnerii
Shigella boydii
Shigella sonnei
GIVE ME THE GENUS AND SPECIES OF THE YERSINIA
Yersinia pestis
Yersinia enterocolitica
Yersinia pseudotuberculosis
Yersinia intermedia
Yersinia kristensenii
Yersinia frederiksenii
Yersinia aldovae
Yersinia ruckeri
GIVE ME THE GENUS AND SPECIES OF THE ESCHERICHIA
Escherichia coli
Escherichia hermannii
Escherichia vulneris
Escherichia fergusonii
Escherichia blattae
o Infrequently encountered in the clinical laboratory as
cause of gastroenteritis
o Associated with water harboring fish and turtles and
rarely on humans
o Opportunistic pathogen to immunocompromised hosts
that may develop serious wound infections and
myonecrosis
GENUS EDWARDSIELLA
It is the only recognized human pathogen in Genus Edwardsiella
Edwardsiella tarda
o Formerly Enterobacter hafniae
o Associated with gastrointestinal linfections
o Resides in GIT of humans and animals
GENUS HAFNIA
o Inhabitants of then asopharynx and GIT
o Absence of motility distinguishes this species from
other members of Enterobacteriaceae family
° Associated with variety of infections including liver
abscess, pneumonia, septicaemia and UTI
GENUS KLEBSIELLA
Most commonly isolated species in the genus Klebsiella
Friedlander’s bacillus
All strains are resistant to ampicillin
Klebsiella pneumonia
CLINICAL INFECTIONS OF KLEBSIELLA PNEUMONIAE
➢ Lower RT infections in hospitalized patients, newborns,
elderly and seriously ill patients on respirators
➢ Wound infections
➢ UTI
➢ Bacteremia
➢ Nosocomial outbreaks in newborn nurseries
➢ Severe enteritis
➢ Septicemia
➢ Meningitis
Only indole (+) member of Klebsiella
Disease is similar to K. pneumoniae
Same strains carry a heat-labile cytotoxin which has
been isolated from patients who have developed a self-
limiting antibiotic associated hemorrhagic colitis
Klebsiella oxytoca
A Klebsiella group 47 which is an environmental organism which also cause UTI and wound infection
Klebsiella planticola
o Normal in habitants of GIT
o Actively motile at 37°C
o NLF
o Able to deaminate phenylalanine
o “Swarming” appearance on BAP
GENUS PROTEUS
Different Proteus strain swarm but does not
swarm with each other leaving a demarcation
line between them
DIENES PHENOMENON
Has same antigenic structure as Rickettsiae. Ag of some strains of this species can be used
to diagnose (Weil Felix Test: OX2, OX19 and
OXk)
Proteus vulgaris
Formerly Proteus vulgaris strain
A newly recognized species
Proteus penneri
o Biochemically similar to Proteus
o Normal inhabitants of GIT
o Most commonly associated with UTI
o Associated with nosocomial outbreaks
o No clear clinical association exists when these
organisms are isolated
GENUS PROVIDENCIA
Formerly Proteus rettgeri
Pathogen of urinary tract
Has caused occasional nosocomial outbreaks
Providencia rettgeri
Nosocomial outbreaks in burn units
Isolated from urine cultures
Providencia stuartii
Associated with gastroenteritis especially in children
Providencia alcalifaciens
o Colonizers and are known to cause pathogenic
infections in health care settings
o Opportunistic pathogens associated with nosocomial outbreaks
o Capable of survival under very harsh environmental conditions
o Resistant to many disinfectants
GENUS SERRATIA
Usually considered clinically important
Frequently found in hospital acquired infections of the
UT and RT
Also associated with bacteremic outbreaks in nurseries,
cardiac surgery and burn units
Serratia marcescens
A non-water soluble red pigment known as
PRODIGIOSIN
Also produces PRODIGIOSIN
Have also been isolated from human sources
Serratia rubidea
Have also been isolated from human sources
Serratia liquefaciens
Gives off a characteristic dirty, musty, pungent odor like potatoes
Serratia odorifera
What biogroup in Serratia odorifera that is Isolated from RT and Ornithine (+), Sucrose (+), may be
indole + (60%)
Biogroup 1
What biogroup in Serratia odorifera that is Isolated from RT
and Ornithine (-), Sucrose (-), may be
indole + (50%)
Biogroup 2
o Found ubiquitously throughout the environment
o Normal in habitants of GIT
o Often associated with stool specimens from patients with symptoms of diarrhea
o Commonly isolated in clinical laboratory, however its clinical significance has not been clearly defined
o Biochemically similar to Proteus
o Can cause UTI
o Has been implicated in post operative infections and other nosocomial infections
GENUS MORGANELLA
Formerly Proteus morganii
Morganella morganii
WHAT ARE THE TRIBE PROTEAE?
Genus Proteus
Genus Providencia
Genus Morganella
Has been identified from blood and wound isolates
Organism is biochemically inactive
Currently, no recommended identification scheme has been identified
GENUS EWINGELLA
This Genus now has been included in the family Enterobacteriaceae.
Fresh water in habitant
Can cause gastroenteritis, most frequently, in children
GENUS PLESIOMONAS
o Facultative anaerobe
o Motile
o Non-encapsulated
o NLF
o Motile with peritrichous flagella except for 2 species
o Isolated from intestines of humans and animals
GENUS SALMONELLA
ID of Genus Salmonella is primarily based on?
✓ Ability of organism to use citrate as the sole
source of carbon
✓ Ability of organism to use lysine as nitrogen
source in combination with H2S production
According to Kauffmann-White Antigenic Scheme
There are 2000 species of Salmonella
because of its antigenic type
According to Ewing
Proposed only 3 species
Eberth’s Bacillus
Salmonella typhosa / typhi
Standard test organism for determining the efficacy of disinfectants
Salmonella cholerasuis
- All other serotypes are defined as serotype of
Salmonella enteritidis - Salmonella typhimurium became Salmonella enteritidis serotype typhimurium
Salmonella enteritidis
WHAT ARE THE TWO PRIMARY SPECIES OF GENUS SALMONELLA?
i. Salmonella enterica (human pathogen)
ii. Salmonella bongori (animal pathogen)
What are the 6 subspecies of Salmonella enterica?
✓ Salmonella enterica subspecie enterica
✓ Salmonella enterica subspecie salamae
✓ Salmonella enterica subspecie arizonae
✓ Salmonella enterica subspecie diarizonae
✓ Salmonella enterica subspecie houtenae
✓ Salmonella enterica subspecie indica
What are the serogroups with unique vilurence properties of Salmonella enterica subspecie enterica?
➢ Salmonella typhi
➢ Salmonella paratyphi
➢ Salmonella choleraesuis
What are the serogroups with unique vilurence properties of Salmonella enterica subspecie enterica?
✓ Salmonella enterica subspecie enterica
➢ Further subdivided into serogroups with
unique virulence properties
➢ Salmonella typhi
➢ Salmonella paratyphi
➢ Salmonella choleraesuis
Most serious pathogens for humans causing
enteric fever
Salmonella enterica subspecie enterica
Formerly Arizona hinshawii
Associated with human infections acquired
from pet turtles, snakes and fish
Salmonella enterica subspecie arizonae
VIRULENCE FACTORS OF GENUS SALMONELLA
➢ Fimbriae for adherence
✓ Ability to traverse intestinal mucosa
➢ Enterotoxin
✓ Causes gastroenteritis
ANTIGENIC STRUCTURE
OF GENUS SALMONELLA
- Heat –Stable Somatic O Antigens
- Heat-Labile Flagellar H Antigens
- Heat-Labile Capsular K Antigens
Treatable with ethanol or acid
Heat-Labile Flagellar H Antigens
What are the two phases of Heat-Labile Flagellar H Antigens?
Phase 1/Specific Phase
Phase 2/Non-specific Phase
✓ Occur only in small number of
serotypes
✓ Agglutinate only with homogenous
antisera
✓ Determine the immunologic identity
of the particular serotype
Phase 1 / Specific Phase
✓ Occur among several strains
✓ React with heterogeneous antisera
✓ Shared by numerous serotypes
Phase 2 / Non-specific Phase
What are the Clinical infections of Genus Salmonella?
Gastroenteritis
Typhoid Fever
➢ Designated as Vi antigen (Virulent Ag)
➢ Found in S. typhi and few other strains
➢ Helps evade phagocytosis
➢ Most often blocks the O Ag during serologic typing
Heat-Labile Capsular K Antigens
➢ Results from ingestion of the organism through
contaminated food
➢ Strains associated are usually found in animals
(serotypes of S. enteritidis)
➢ Sources of infection poultry, milk, eggs and egg
products as well as handling pets
➢ Occurs when sufficient number of organism contaminate food that is maintained under inadequate refrigeration, thus allowing growth and multiplication of the organism
GASTROENTERITIS
What is the Infective Dose of Salmonella in Gastroenteritis?
10,000,000 bacteria
What are the antimicrobials of choice for salmonella?
Chloramphenicol
Ampicillin
Trimethoprim Sulfamethoxazole
➢ Enteric Fever caused by S. typhi
➢ Results from the ingestion of food contaminated with the organism originating from infected individuals as carriers
TYPHOID FEVER
What are the Clinical Features of Typhoid Fever?
✓ Prolonged fever
✓ Bacteremia
✓ involvement of RES (particularly liver, spleen,
intestines and mesentery)
✓ dissemination to multiple organs
✓ develops approximately 9-14 days after
ingestion of the organism depending on the
number of organisms ingested
➢ Caused by non-typhoidal Salmonella
➢ Characterized primarily by prolonged fever and
intermittent bacteremia
➢ Most commonly associated strains are; S. typhimurium, S. paratyphi A and B, S. cholerasuis
BACTEREMIA
Individuals who recover from the infection may harbour the organisms in the gallbladder which becomes the site
of chronic carriage
CARRIER STATE
- Very closely related to Escherichia, belongs to tribe
Escherichieae - All species can cause bacillary dysentery but vary in
epidemiology, mortality rate and severity of disease
produced - Highly communicable because of the low infective dose required to produce the disease
GENUS SHIGELLA
It is characterized by the presence of blood,
mucus and pus in the stool
✓ Occurs in an epidemic dimension
Dysentery
______ with shigellosis may transiently lose the reflexive closing of the anal canal with external pressure as from a cotton swab
Infants
The only reservoir of Shigella
Humans
WHAT ARE THE CLASSIFICATION OF SHIGELLA BASED ON MANNITOL FERMENTATION?
A. NON-MANNITOL FERMENTERS
B. MANNITOL FERMENTERS
- Dysentery Bacillus or Shiga’s Bacillus
- Very Infectious
Shigella dysenteriae
Two types of Toxin of Shigella dysenteriae
Exotoxin- neurotoxin
Enterotoxin- similar to cholera toxin
what Shigella species are Non-Lactose Fermenters?
Shigella flexnerii
Shigella boydii
Strong’s Bacillus
Shigella flexnerii
Boyd’s Bacillus or Newcastle-Menchester Bacillus (new name)
Shigella boydii
what are the two types of Mannitol Fermenters?
Non-Lactose Fermenters
Late Lactose Fermenters
Sonne Duval Bacillus or Sonne’s Bacillus
Shigella sonnei
Suspected strains that cannot be typed by serologic
methods should be referred to a ________ for further testing
reference laboratory
Remains the most virulent species with significant
morbidity and high mortality
Shigella dysenteriae
What are the COMPLICATIONS of Shigella dysenteriae?
➢ Obstruction in the intestines with marked abdominal dilatation possibly leading to toxic mega colon
➢ Bacteremia
➢ Seizures : may occur during Shigella strain infection
➢ HUS (Hemolytic Uremic Syndrome), exclusively
associated with S. dysenteriae type 1 shigellosis
Leading isolate in “GAY BOWEL SYNDROME”
Shigella flexneri
✓ Predominant isolate in the US followed by S. flexneri
✓ Infection is usually short
✓ Self-limiting disease characterized by fever and watery
diarrhea
Shigella sonnei
GENUS YERSINIA
was named after a French Microbiologist
and who isolated the plague bacillus 1894
Alexander Yersin
Microaerophilic
and Short Gram (-) coccobacillus
Genus Yersinia
A Causative agent of plague that shows intense staining at each end of the bacillius
referred to as ”bipolar staining” using Wayson Stain or Methylene Blue giving a “safety pin” appearance
Yersinia pestis
A life –threatening disease of rodents transmitted to
humans by bites of fleas
PLAGUE
This type of vector fleas that normally infest brown and black rats
Xenopsylla cheopsis
THREE (3) PLAGUE PANDEMIC
- Started near Egypt in 542 AD, ravaged Europe for 50 years, killing 100 M people
- Started in the 14thCentury –The Black Death, killing 25 M Europeans, ¼ of the population at that time
- Started in Burma in 1890’s and spread to many parts of the world
WHAT ARE THE FORMS OF PLAGUE?
A. BUBONIC PLAGUE / GLANDULAR PLAGUE
B. PNEUMONIC PLAGUE
C. SEPTICEMIC PLAGUE
➢ Usually results form the bite of an infected
insect vector
➢ Characteristic symptoms appear 2 –5 days
after infection
➢ Symptoms include high fever with painful
regional lymph nodes as buboes begin to
appear
BUBONIC PLAGUE / GLANDULAR PLAGUE
Occurs secondary to the bubonic plague
when organisms proliferate in the blood stream and respiratory tract
Fatality rate is high if patients remain untreated
90% mortality rate
PNEUMONIC PLAGUE
➢ 97-99% Mortality Rate
➢ Black Death – black purpuric lesions all over
the body called as “Generalized Schwartzman Phenomenon”
SEPTICEMIC PLAGUE
LABORATORY DIAGNOSIS OF A YERSINIA PESTIS
➢ Stained Smear
➢ Culture
➢ Transport Medium
➢ Animal Inoculation Test
➢ Fluorescent Antibody Test
Most commonly isolated species of the genus
Morphologically resembles other Yersinia species: g(-) coccobacilli, bipolar staining
Also grows on routine media, BAP, MCA
Has optimal growth temperature of 25°C –30°C
Motility is clearly noted at 25C but not at 35 C
Cold enrichment has provided better recovery
Yersinia enterocolitica
A selective medium to detect the presence of Yersinia enterocolitica
CIN Agar
Yersinia enterocolitica infection manifest in several forms
Acute Enteritis
Mesenteric Lymphadenitis
Arthritis
Erythema Nodosum
Appears as atypical looking plague bacillus
May be differentiated from Y. pestis by its motility at 18 C-22 C, production of urease and the ability to ferment rhamnose
Yersinia pseudotuberculosis
Yersinia pseudotuberculosis causes a disease characterized by caseous swelling called
pseudotubercles
Most significant species in the genus
Associated with GIT, UT, Meningeal (newborns), Wound and Bacteremic Infections
Most strains are motile
Possess both sex pili and adhesive fimbriae
Escherichia coli
FIVE MAJOR CATEGORIES OF DIARRHEAGENIC E. COLI
- Enteropathogenic E coli (EPEC)
- Enterotoxigenic E. coli (ETEC)
- Enteroinvasive E. coli (EIEC)
- Enterohemorrhagic E. coli (EHEC)
- Enteroaggregative/ Enteroadherent E. coli (EAEC)
TWO CATEGORIES OF EXTRAINTESTINAL E. COLI INFECTIONS
UROPATHOGENIC E. COLI (UPEC)
MENINGITIS/ SEPSIS-ASSOCIATED E.. COLI (MNEC)
OTHER EXTRAINTESTINAL E. COLI INFECTIONS
- BACTEREMIA
- Nosocomial Infections of other body sites
➢ coli atypical or enteric group ll
➢ Has been isolated from spinal fl
Escherichia hermannii
➢ Isolated from wound
➢ May also produce yellow pigmented colonies
(more than half of the strains)
Escherichia vulneris
➢ From scientist William Ferguso
➢ Multiple abscesses following a gunshot to the abdomen
Escherichia fergusonii
Has only been isolated from the intestine of
cockroach
Escherichia blattae
ANTIMICROBIAL SUSCEPTIBILITY TESTING GROUP A
✓ Ampicillin
✓ *Cefazolin
✓ Gentamicin
✓ Tobramycin
ANTIMICROBIAL SUSCEPTIBILITY TESTING GROUP B
✓ Amikacin
✓ Amoxicillin-clavulanate
✓ Ampicillin-Sulbactam
✓ Piperacillin-tazobactam
✓ Ticarcillin-clavulanate
✓ Cefuroxime
✓ Cefepime
✓ Cefoxitin
✓ Cefotaxime or Ceftriaxone
✓ Ciprofloxacin
✓ Levofloxacin
✓ Imipenem
✓ Meropenem
✓ Trimethoprim-sulfamethoxazole
ANTIMICROBIAL SUSCEPTIBILITY TESTING
GROUP C
✓ Aztreonam
✓ Ceftazidime
✓ Chloramphenicol
✓ Tetracycline
ANTIMICROBIAL SUSCEPTIBILITY TESTING
GROUP O
✓ Aztreonam
✓ Ceftazidime
✓ Chloramphenicol
✓ Tetracycline
GROUP O
✓ Cefamandole
✓ Cefoperazone
✓ Ceftizoxime
✓ Cefaclor
✓ Cefixime
✓ Cefpodoxime
✓ Kanamycin
✓ Netilmicin
✓ Streptomycin
✓ Doxycycline
✓ Minocycline
✓ Gatifloxacin
✓ Cinoxacin
✓ Nalidixic Acid
ANTIMICROBIAL SUSCEPTIBILITY TESTING
GROUP U
✓ *Cefazolin
✓ Lomefloxacin or
✓ Ofloxacin
✓ Norfloxacin
✓ Nitrofurantoin
✓ Trimethoprim
An adhesion known as ___________ is a major virulence factor of Enteropathogenic E coli (EPEC)
INTIMIN
For definitive ID, enteroinvasiveness must be
demonstrated:
a. Serenty Test – bioassay with a positive result of Keratoconjunctivitis in guinea pig
b. Monolayer cell cultures with Hep-2 cells
Also known as Verotoxin-Producing E. coli (VTEC) and Serotoxigenic E. coli (STEC)
Enterohemorrhagic E. coli (EHEC)
WHAT ARE THE TWO CYTOTOXINS OF Enterohemorrhagic E. coli (EHEC)?
a. Verotoxin I
➢ Serologically cross-reactive with Shiga toxin
b. Verotoxin II
➢ Not neutralized by the Ab to Shiga toxin
- Associated with diarrhea in both adults and infants in tropical and sub tropical climates
- Major cause of infant diarrhea in developing countries
- Major cause of “travellers diarrhea” among persons
from developed countries visiting third world countries
Enterotoxigenic E. coli (ETEC)
- Actual pathogenic mechanism is unknown
- Mode of transmission not well understood
Enteroaggregative/ Enteroadherent E. coli (EAEC)
Major cause of E. coli associated UTI
UROPATHOGENIC E. COLI (UPEC)
Causes neonatal meningitis resulting to high morbidity and moratlity
MENINGITIS/ SEPSIS-ASSOCIATED E.. COLI (MNEC)