GNR: Enterbacterales + Vibrionaceae Flashcards
Characteristics of Enterics
facultatively anaerobic GNRs, fermenters, metabolize glucose, oxidase negative, reduce nitrate, catalase positive
E. coli diseases
1 cause of UTIs, bacteremia, meningitis, and diarrhea
Which strains of E. coli cause gastrointestinal disease?
STEC (O157/non-O157), ETEC, EPEC, EIEC, and EAEC
Shiga toxin-producing E. coli symptoms/risks
mild diarrhea, hemorrhagic colitis (bloody diarrhea), or no symptoms; can develop hemolytic uremic syndrome (HUS), which can lead to kidney failure
Other strains of E. coli symptoms
ETEC: traveler’s diarrhea
EPEC: infantile diarrhea (<5 yrs)
EIEC: dysentery-like disease
EAEC: associated with chronic, persistent diarrhea
Which enterics are diarrheal pathogens (cause diarrheal disease whenever present)
Salmonella, Shigella, Yersinia enterocolitica/pseudotuberculosis, Campy jejuni/coli, Plesiomonas shigelloides, and Edwardsiella tarda
How is E. coli O157 differentiated from other E. coli strains?
E. coli O157 is sorbitol negative, so a special media with sorbitol can be used (Sorbitol MAC) where O157 will be clear
Shigella spp. diseases and symptoms
Shigellosis- invades the intestinal mucosa leading to abdominal pain, fever, watery diarrhea that can be bloody
Reactive arthritis/Reiter’s chronic syndrome- associated with serogroup B
Edwardsiella tarda diseases
uncommon cause of infections, but can cause diarrhea, wound infections, and bacteremia; associated with cold-blooded animals (snakes and turtles)
Which medical conditions increase the likelihood for a systemic infection caused by Edwardsiella tarda?
Patients with liver disease or conditions with iron overload; immunocompromised people can develop myonecrosis and liver abscesses in addition to systemic disease
Salmonella enterica diseases and symptoms
Gastroenteritis- food poisoning, causing nausea, vomiting, fever, abdominal pain, and diarrhea (usually self limiting)
Enteric fever- S. typhi (typhoid fever), S. paratyphi A/B (paratyphoid fever), or S. cholerasuis; fever, prostration, bacteremia, and organ failure
Other infections include bacteremia, osteomyelitis, meningitis, and endocarditis
Symptoms of Typhoid fever
More severe than the other enteric fevers; can have “rose spot” (red lesions on the abdomen) along with other enteric fever symptoms; blood is usually positive the first week, but stool and urine are more likely to be positive the second and third week
Citrobacter spp. diseases
UTIs, wound, respiratory, bacteremia, endocarditis, septicemia, meningitis, and brain abscesses
Enterobacter spp. diseases
associated with contaminated medical devices
Klebsiella spp. diseases
UTIs, respiratory (pneumonia), bloodstream; K. granulomatis is an STD
Symptoms of Klebsiella granulomatis infection
causes granuloma inguinale/donovanosis, leading to genital ulcers/painless lesion that bleed easily
How is a Klebsiella granulomatis infection diagnosed?
Need egg yolk growth factors to grow, so lesion scrapings are stained with Wright or Giemsa stain along with clinical manifestation for diagnosis; blue rods with prominent polar granules (safety pin)
Serratia marcescens diseases
causes healthcare infections and associated with medical devices and solutions; resistant to a lot of disinfectants
Pantoea agglomerans diseases
associated with traumatic injury from objects contaminated with soil
Hafnia alvei diseases
causes opportunistic infections and abscesses in the biliary tree
Which genera are included in the Proteeae group and what biochemical does this group have?
Proteus spp., Morganella spp., and Providencia; all three are positive for phenylalanine deaminase and lactose negative
Proteus spp. diseases
UTIs, wound infections, and ear infections; associated with diarrhea and sepsis
Morganella spp. diseases
associated with diarrhea
Providencia spp. diseases
associated with nosocomial infections, UTIs, and diarrhea in children
Yersinia pestis diseases and symptoms
causes plague (from rodents or infected fleas); bubonic plague- fever and swollen lymph nodes (buboes); pneumonic plague- infections of the respiratory tract from inhalation of droplets
Yersinia enterocolitica diseases and symptoms
causes enterocolitis and can mimic acute appendicitis because of mesenteric lymphadenitis
Yersinia pseudotuberculosis diseases and symptoms
rarely causes human disease; primarily found in rodents, rabbits, and wild birds
Appearance of E. coli on different agars
EMB: metallic green
MAC: pink
SS: pink
HEK: yellow-orange
XLD: yellow
Appearance of Klebsiella and Enterobacter on different agars
EMB: blue-black
MAC: pink
SS: pink
HEK: yellow-orange
XLD: yellow
Appearance of Shigella spp. on different agars
EMB: colorless
MAC: colorless
SS: colorless
HEK: green
XLD: red
Appearance of Salmonella spp. on different agars
EMB: colorless
MAC: colorless
SS: colorless w/ black center
HEK: green/blue w/ black center
XLD: red w/ black center
Appearance of Proteeae, Citrobacter, Serratia, and Hafnia on different agars
EMB: lavender or colorless
MAC: colorless to slightly pink
SS: colorless w/ or w/o black centers
HEK: green to salmon w/ or w/o black centers
XLD: red or yellow w/ or w/o black centers
E. coli biochemicals
Positive: lactose, ONPG, indole, methyl red, motile, lysine
Negative: VP, citrate, urea, H2S
TSI: A/AG-
Shigella spp. biochemicals
Positive: Methyl red
Negative: lactose, H2S, VP, citrate, arginine, lysine, ornithine, motility, urea
Indole variable
TSI: K/A-
Shigella sonnei vs other spp.
ONPG positive because it is a late lactose fermenter and it is ornithine positive
Salmonella spp. biochemicals
Positive: H2S, methyl red, citrate, lysine, ornithine, and motile
Negative: lactose, indole, VP, urea
TSI: K/AG+
Salmonella typhi biochemicals
Positive: H2S (slight), methyl red, motile, lysine
Negative: lactose, citrate, ornithine, VP, indole
TSI: K/A+ (no gas)
Edwardsiella tarda biochemicals
Positive: H2S, indole, methyl red, lysine, ornithine, motile
Negative: lactose, VP, citrate, arginine, urea
TSI: K/AG+
Citrobacter spp. biochemicals
Positive: ONPG, methyl red, citrate, motile
Negative: lysine, VP, urea
TSI: V/A and variable for gas and H2S
Citrobacter freundii vs Citrobacter braakii vs Citrobacter youngae vs Citrobacter koseri
C. freundii- indole negative, H2S positive, ornithine negative
C. braakii- indole negative, ornithine positive
C. youngae- ornithine negative, indole v
C. koseri- indole positive, ornithine positive
Klebsiella spp. biochemicals
Positive: gas, lysine, lactose, VP, citrate, urea
Negative: H2S, ornithine, nonmotile
TSI: A/AG-
Klebsiella pneumoniae vs Klebsiella oxytoca
K. pneumoniae is indole negative while K. oxytoca is indole positive
Enterobacter spp. biochemicals
Positive: gas, ornithine, VP, citrate, lactose, ONPG
Negative: H2S, indole, methyl red
TSI: A/AG-
Enterobacter aerogenes vs Enterobacter cloacae
E. aerogenes- lysine positive and arginine negative
E. cloacae- lysine negative and arginine positive
Serratia marcescens biochemicals
Positive: motile, ONPG, citrate, VP, lysine, ornithine, lactose, sucrose
Negative: H2S, indole, urea, gas, arginine
TSI: A/A
Proteus spp. biochemicals
Positive: urea, motile, H2S, methyl red, phenylalanine, gas
Negative: lactose, arginine, lysine, VP
TSI: K/AG+ or A/AG+ if sucrose positive strain
Proteus mirabilis vs Proteus vulgaris
P. mirabilis: indole negative, ornithine positive, citrate positive, sucrose negative, gelatin negative, maltose negative
P. vulgaris: indole positive, ornithine negative, citrate negative, sucrose positive, gelatin positive, maltose positive
P. mirabilis is also susceptible to ampicillin while vulgaris is resistant
Proteus hauseri and Proteus penneri specific biochemicals
P. hauseri: indole positive, ornithine negative, maltose positive
P. penneri: indole negative, ornithine negative, maltose negative
Providencia spp. biochemicals
Positive: indole, methyl red, citrate, phenylalanine, motile
Negative: lactose, H2S, VP, arginine, lysine, ornithine
TSI: V/A V-
Providencia specific spp. biochemicals
P. alcalifaciens: indole +, maltose +, urea -
P. heimbachae: indole -, urea -
P. rettgeri: indole +, urea +, maltose -
P. stuartii: indole +, urea v, maltose -
P. rustigianii: indole +, urea -, maltose -
Morganella morganii biochemicals
Positive: indole, urea, ornithine, methyl red, phenylalanine, motile
Negative: lactose, H2S, VP, citrate, arginine, lysine
TSI: K/AG-
Hafnia alvei biochemicals
Positive: citrate, motile, lysine, ornithine
Negative: indole, H2S, urea, arginine
TSI: K/AG-
Yersinia spp biochemicals
Positive: methyl red
Negative: oxidase, lactose, H2S, VP, citrate, lysine, arginine
TSI: based on spp.
- Y. entercolitica A/A-
- Y. pseuodotuberculosis K/A-
Yersinia pestis vs Yersinia enterocolitica vs Yersinia pseudotuberculosis biochemicals
Y. pestis: indole -, nonmotile, urea -, ornithine -, sucrose -, rhamnose -
Y. enterocolitica: indole v, motile, urea +, ornithine +, sucrose +, rhamnose -, ONPG +
Y. pseudotuberculosis: indole -, motile, urea +, ornithine -, sucrose -, rhamnose +
Yersinia enterocolitica vs Shigella sonnei vs Aeromonas spp.
Y. enterocolitica is urea positive, sucrose positive, rhamanose negative, and sorbitol positive
S. sonnei is urea negative, sucrose negative, rhamanose positive, and sorbitol negative
Aeromonas is oxidase positive
Plesiomonas shigelloides biochemicals
Positive: oxidase, motile, indole, ONPG, lysine, arginine, ornithine, methyl red, catalase, inositol
Negative: VP, H2S, urea, citrate, gas
TSI: A/A-
does not grow on amp containing agars
Raoultella spp. biochemicals
Positive: VP, ONPG, 10C growth
Negative: 44C growth
Raoultella ornithinolytica vs. R. planticola vs. R. terrigena
R. ornithinolytica- indole positive and ornithine positive
R. planticola- ornithine negative and indole variable
R. terrigena- indole negative and ornithine negative
How are Vibrio infections usually aquired?
Usually occur after raw fish consumption or wounds in contact with contaminated fish. Cases increase in warmer months
Which species are Vibrio causes endemic, epidemic, and pandemic cholera?
Vibrio cholerae, which has 2 biotypes (classical O1 and E1 Tor). E1 Tor caused the last pandemic while O1 caused the ones before it.
Vibrio cholerae diseases
causes both intestinal and extraintestinal infections. Gastroenteritis can be asymptomatic to fatal from dehydration; causes watery diarrhea (“rice water” diarrhea- colorless and contain mucus flecks). Extraintestinal infections include bacteremia, wound infections, and ear infections
Which toxins does Vibrio cholerae have?
Cholera toxin (CT): causes mucosal cells to hypersecrete water and electrolytes into the lumen of the GI tract leading to dehydration and watery diarrhea; does not penetrate the mucosal barrier so no blood
Zonula occludens toxin (ZOT): disrupts the tight junctions of the intestinal cells, decreasing tissue resistance
Toxin coregulated pili (TCP): allows bacilli to attach to mucosal cells for CT release
Which Vibrio species is associated with liver disease and raw oysters?
V. vulnificus causes septicemia and wound infections usually after handling raw oysters; it mainly affects those with liver disease due to the increased availability of iron
Which species of Vibrio is associated with infections following exposure to sea water?
V. alginolyticus causes ear and wound infections after exposure to sea water
General characteristics of Vibrio spp.
motile, oxidase positive, ferment glucose (except V. metschnikovii), all of nlf (except V. vulnificus), indole positive
Which species of Vibrio require only 0.5% NaCl to grow while other need a higher concentration?
V. cholerae and V. mimicus
Which agar should be used for Vibrio isolation and differentiation?
TCBS: species that ferment sucrose will be yellow while those that do not are green
Biochemicals for key Vibrio spp.
V. alginolyticus: ONPG -, ADH -, LDC +, ODC var, Sucrose +
V. cholerae: ONPG +, ADH -, LDC +, ODC +, Sucrose +, VP +, TSI: A/A-
V. parahaemolyticus: ONPG -, ADH -, LDC +, ODC +, Sucrose -, VP -, TSI: K/A-
V. vulnificus: ONPG var, ADH -, LDC +, ODC var, Sucrose -, only species that is salicin +, VP -, A/A-
What is the string test?
The string test is used to differentiate between Vibrio, Aeromonas, and Plesiomonas; organisms are emulsified in 0.5% sodium deoxycholate, which will lyse Vibrio cells. The lysed Vibrio cells will release DNA, which can be pulle dup into a string with a loop
Aeromonas spp. diseases
causes infections when contaminated food/water is ingested, disrupted skin is exposed to contaminated water, or traumatic inoculation of fish fins or fishing hooks; can cause gastroenteritis, septicemia, necrotizing fasciitis, bacteremia, pneumonia, conjunctivitis, wound infections, endocarditis, and osteomyelitis. Can lead to HUS and kidney disease
General Biochemicals for Aeromonas spp.
indole positive, oxidase positive, motile, often lactose or sucrose positive, does not grow in salt, ODC negative, Resistant to O/129, inositol negative, TSI: A/AG-
What has led to an increase in Aeromonas infections?
natural disasters such as flooding and tsunamis have led to an increase in infections; it is also associated with leech therapy
Which medias can be used for Aeromonas?
CIN w/ cefsulodin, Ampicillin blood agar (except for A. trota which is Susceptible to amp), Aeromonas agar (contains D-xylose to differentiate it from Yersinia and Citrobacter and Oxidase test can be done unlike CIN agar)
Which Aeromonas species in ADH negative?
A. veronii biovar veronii is the only negative species (biovar sorbia is positive)
Which Aeromonas species in ODC positive?
A. veronii biovar veronii is the only positive species (biovar sorbia is negative)
A. caviae biochemicals
Positive: esculin, salacin, and KCN
Negative: gas and VP
A. hydrophila biochemicals
Positive: esculin, salacin, gas, VP, and KCN
A. veronii biochemicals
Positive: gas and VP
Negative: esculin, salacin, and KCN
Helicobacter spp. diseases
H. pylori causes gastritis, peptic ulcer disease, and gastric cancer
Other helicobacters can cause proctocolitis, gastroenteritis, neonatal meningitis, skin rashes, and bacteremia
Helicobacter spp. biochemicals
All are oxidase +, catalase +, microaerophilic, grows at 37C, and motile
H. pylori: urease +, nitrate -, resistant to nalidixic acid
H. cinaedi: urease -, nitrate +, susceptible to nalidixic acid
H. fennelliae: urease -, nitrate -, susceptible to nalidixic acid
What tests can be done to identify H. pylori?
Urease tests- biopsy test where biopsy is incubated in Christensen’s urea medium for 2 hours (pink is +) or breath test where a patient drink a solution with 14C labeled urea and then 14CO2 is detected
Campylobacter spp. diseases
Febrile systemic disease, periodontal disease, and most commonly gastroenteritis (Campy jejuni is the most common bacterial enteric pathogen and causes infections during summer and early fall)
Biochemicals for select Campylobacter species
C. coli: NG at 25C and growth at 42C, hippurate -, H2S -, nitrate +, Resist cephalothin and Suscept Nalidixic acid
C. jejuni: NG at 25C and growth at 42C. hippurate +, H2S -, Resist cephalothin and Suscept Nalidixic acidC. fetus: growth at 25C and NG at 42C, hippurate -, H2S -, nitrate +, Suscept cephalothin and resist nalidixic acid
How are the subspecies of C. jejuni differentiated from each other?
C. jejuni sub. jejuni is nitrate positive while C. jejuni sub. doylei is negative
General characteristics of Campy spp.
seagull wing appearance on GS, oxidase positive, motile, catalase positive, urease -
