gram negative cell wall
thin peptidoglycan wall surrounded by outermembrane containing LPS
most G- rods are in the family
enterobacteriacea
G- rods are the most common cause of
diarrhea and UTIs
gram negative rods tend to be resistant to
penicillin and vancomycin
G- bacteria retain what part of the gram stain
safranin
klebsiella pneumoniae identifying features (6)
G-rodnon-motileencapsulatedrapid lactose fermenter
motility of klebsiella
non-motile, no flagellum
lactose fermenting status of klebsiella
RAPID lactose fermenter
klebsiella infects what kinds of hosts
immunocompromised- alcoholics- diabetics- nosocomial
infections associated with klebsiella pneumoniae
lobar pneumonialung abscessesUTIs (rare)liver abscesses
pneumonia in klebsiella infection
RED CURRANT JELLY sputumoften occurs after aspiration of GI contents
red currant jelly sputum
Klebsiella pneumoniae
pneumonia resulting from klebsiella infection often results from
aspiration of GI contents (alcoholics)
lung abscesses are usually caused by
mouth anaerobes
number one cause of UTIs
E. coli
number two cause of UTIs
s. saprophyticus
liver abscesses in klebsiella infection may result in patients with
underlying liver disease (alcoholics)
pt with long history of alcohol abuse, presenting with lobar pneumonia, liver abscesses, and a red currant jelly sputum
klebseilla pneumoniae
pathogenicity of E. coli
most non-pathogenic normal gut flora
selected virulence factors of pathogenic E coli species
fimbriae/pilicapsule with K antigen
K1 antigen
capsular antigen found on some strains of E. coli
capsulated status of E. coli
most are non-capsulatedsome strains have a capsule with K1 antigen
K1 antigen is found in 75% of
E. coli induced infant meningitis
role of K antigen
inhibit phagocytosis and complement activation
number one cause of pyelonephritis
E. coli
E. coli bacteremia/sepsis
rare, but would result from UTI typically if it occurs (secondary bacteremia)
infections associated with E. coli
UTI/pyelonephritisdysentery or water diarrheameningitis
lactose fermenting status of E. coli
RAPID lactose fermenter
major types of pathogenic E. coli
EIECEPECETECEHEC
which strains of E. coli cause bloody diarrhea
EIECEHEC
which strains of E. coli cause watery diarrhea
EPECETEC
enteroinvasive E. coli (EIEC)
Invades the intestinal mucosa cause necrosis, inflammation and bloody diarrhea
EIEC similarity to shigella
similar but NO TOXINS
which pathogenic strains of E. coli produce toxins
ETECEHEC
which pathogenic strains of E. coli do not produce toxins
EIECEPEC
which pathogenic strain of E. coli produces a shiga-like toxin
EHEC
which infection of a pathogenic strain of E. coli occurs mostly in children
EPECthink: P for pediatric
enteropathogenic E. coli (EPEC)
blunt vill prevents absorptionno toxin, no inflammation
EPEC causes
diarrhea, usually in children
which strains of E. coli do not cause inflammation
EPECETEC
ETEC
T = Traveler's diarrhea (watery)T = Two Toxins - labile and heat stable
toxins of ETEC
labile and heat stable
which pathogenic strain of E. coli is associated with traveling
ETEC
classic serotype of EHEC
O157:H7
EHEC grows on
sorbitol-macconkey
EHEC toxin
Shiga-like toxin
which pathogenic strain of E. coli invades host cells
EIEC
cause of bloody diarrhea in EIEC
invasion of ORGANISM
cause of bloody diarrhea in EHEC
shiga-like TOXIN (bacteria doesn't invade host cells)
EHEC infection may result from consumption of
undercooked beef
effects of EHEC shiga-like toxin
swelling of endothelium in GI vessels --> narrowing of lumen --> deposition of fibrin and platelets --> inflammation, necrosis, bleeding
hemolytic uremic syndrome caused by
EHEC
HUS occurs in
10% of EHEC infections
HUS is most often observed in
children
HUS triad
hemolytic anemiathrombocytopenia (petechiae of lower legs, ecchymosis, etc)acute renal failure (uremia)
HUS usually occurs how many days after dysentery in EHEC
5 to 7 days
enterobacter is and occasional cause of nosocomial
UTI
lactose fermenting status of enterobacter
RAPID lactose fermenting
virulence factor of enterobacter
extended spectrum beta lactamase
extended spectrum beta lactamase
enterobacter resistance factor
enterobacter is resistant to most
beta lactams- penicillin- cephalosporins- aztreonam
citrobacter
normal gut floraoccasional sepsis
citrobacter gram stain
G- rod
citrobacter lactose fermenting status
SLOW lactose fermenter
serratia gram stain
G- rod
serratia colonies
red colonies
red colonies on growth media
serratia
catalase of serratia
positive
serratia infections
nosocomialmay cause osteomyelitis in IV drug users
osteomyelitis in IV drug users
serratia
identifying characteristics of citrobacter (3)
G-rodslow lactose fermenter
identifying characteristics of serratia (4)
G-rodslow lactose fermentercatalase positive
lactose fermenters mnemonic (and what are they)
macConKEESCitrobacter (slow)Klebsiella (rapid)E. coli (rapid)Enterobacter (rapid)Serratia (slow)
types of salmonella (3)
typhoidal: s. typhinontyphoidal: s. enterica and enteriditis
non-typhoid strains of salmonella
S. entericaS. enteriditis
non-typhoidal strains of salmonella cause
enteritis
major shared identifying features of salmonella (4)
G-rodsencapsulatedmotile
capsule status of salmonella
encapsulated
motility of salmonella
motile (flagellated)
unique feature of immune response elicited by S. typhi
largely monocytic
H2S test
used to differentiate shigella from salmonellasalmonella turns media black
how to differentiate shigella from salmonella
TSI- salmonella produces H2S and turns media black
infection of S. enterica causes
INVASIVE gastroenteritis
symptoms of invasive gastroenteritis resulting from non-typhoidal (enterica) salmonella infection
N/V/C/bloody diarrhea
diarrhea in S. enterica infection
bloody
normal flora location for s. enterica
guts of reptiles, birds, mammals
s. enterica infection may occur following the ingestion of
contaminated eggs, poultry
if s. enterica disseminates through the blood, it may cause
osteomyelitis
symptoms of typhoid fever
fever, diarrhea, abdominal pain, headache+rose spots, pulse/temp dissociation
typhoid fever typically involves travel to
africa, asia, south america
classic presentation of salmonella typhi
rose spotspulse temperature dissociateosteomyelitis (if sickle cell)
number one cause of osteomyelitis in patients with sickle cell anemia
S. typhi
pt with sickle cell anemia and osteomyelitis
S. typhi
rose spots
s. typhisalmon color macules on trunk and abdomen
salmon colored macules on trunk and abdomen
S. typhi
pulse temperature dissociation
high fever with low pulse
shigella motility
non-motile
shigella stain
G-
identifying characteristics of shigella (3)
G-rodnon-motile
immune response illicited by shigella infection
largely PMNs
immune response in salmonella vs shigella
salmonella: monocytic shigella: PMN
what is invaded in salmonella enterica infection
GI mucosa
what is invaded in shigella infection
M cells of peyer's patches
invasion of peyer's patch M cells
shigella
H2S status salmonella
positive
H2S status shigella
negative
oxidase status of shigella
negative
lactose fermenting status of shigella
negative
major identifying characteristics of shigella (6)
G-rodnon-motilenon-lactose fermenteroxidase negativeH2S negative
how does shigella invade M cells
macropinocytosis
when shigella invades M cells, what is the result
apoptosis
how does shigella infection spread
CELL TO CELLNOT BLOODSTREAM
difference in spread of infection: salmonella vs shigella
salmonella: bloodstreamshigella: cell to cell
shigella toxin
shiga toxin
bacteria needed to cause disease in shigella infection
VERY low (roughly 10)
major identifying features of proteus (6)
G-rodurease positiveswarming phenotypenon-lactose fermenteroxidase negative
lactose fermenting status of proteus
negative
urease status of proteus
positive
swarming phenotype
proteus
bulls-eye on blood agar
proteus
proteus infection is associated with
struvite kidney stone formation
struvite kidney stone formation
proteus
major identifying features of pseudomonas aeruginosa (7)
G-rodobligate aerobewater lovingoxidase positivenon-lactose fermentingcapsulated
which G- rod loves water
P. aeruginosa
environmental preference of P. aeruginosa
aerobic (obligate)water
lactose fermenting status of P. aeruginosa
non-fermenting
oxidase status of P. aeruginosa
positive
P. aeruginosa colonies on media
fluorescent green
fluorescent green colonies on culture media
P. aeruginosa
pigment produced by P. aeruginosa
pyocyanin
odor of P. aeruginosa
grape like(think green grape colonies)
hot tub folliculitis
Pseudomonas aeruginosa
mnemonic for P. aeruginosa associated infections (and what are they)
BE PSEUDOBurnsEndocarditisPneumoniaSepsisExternal otitis (swimmer's ear)UTIDrug usersOsteomyelitis
which G- rod is known to cause swimmer's ear (otitis externa)
P. aeruginosa
pneumonia in P. aeruginosa infection especially prevalent in patients with
CF
most common cause of peptic ulcers
H. pylori
major identifying characteristics of Helicobacter pylori
G-rodmotikemicroaerophilicurease positive
environmental preference of H. pylori
microaerophile
H. pylori causes
peptic ulcersgastritis
urease status of H. pylori
positive
how does H. pylori survive in the acidic stomach
urease hydrolyzes urea to ammonia (alkaline)
test for H. pylori
urea breath test (labelled urea - detection of isotype)
method of legionella transmission
aerosol (NOT airborne)
legionella classically associated with
contaminated water in hotel a/c cooling tanks
gram staining of legionella
G- (doesn't stain well, use silver stain instead)
what stain is used for identification of legionella
silver stain
special culture requirement of legionella
buffered charcoal yeast extract- contains Fe and Cys for growth- contains antibiotics to inhibit growth of other species- silver dyes for contrast
classic infection of legionella
pneumonia in nursing homes resulting/contaminated AC tanks
what metabolic disturbance is associated with legionella infection
hyponatremia
diarrhea in legionella
watery
symptoms of legionella
severe pneumoniawatery diarrheaN/V/APhyonatremia
nursing home pt presenting with watery diarrhea, pneumonia, hyponatremia
legionella
mnemonic for bacteria that don't gram stain well (and what are they)
These Rascals May Microscopically Lack ColorTreponemaRickettsiaMycobacteria (mycolic acid)Mycoplasma (no cell wall)LegionellaChlamydia (no peptidoglycan, lacks muramic acid)
major identifying characteristics of Bacteroides (3)
G-Rodobligate anaerobe
bacteroides infections are usually
POLYMICROBIAL
infections associated with bacteroides fragilis
polymicrobial- peritonitis- intra-abdominal abscesses- lung abscesses
B. fragilis infections tend occur in junction with
E. coli/GNR infections
fecal leukocytes indicate
INVASIVE INFECTION --> bloody diarrhea
mucous/epithelial cells in fecal matter indicate
TOXIN mediated disease