Week 6 Flashcards
Where are non fermenters usually found
Ubiquitous in hospitals (dialysate fluids, nebulizers)
-they colonize pt
-resist chlorhexidine and QUATs treatment
-will be oxidizer
Alcaligenes
acenetobacter
achromobacter
elizabethking
What are a few characteristics of Non Fermenter GNB
-small GNB or GNCB
-non oxidizer or non CHO utilizer
-better in aerobic conditions - strict aerobe
How do we ID other GNB Non-Enterobacteriaceae through biochemical tubes
-non fermenter
-no TSI changes in butt or slant only . The no acid at the top means that it can use peptones and no change at the bottom because they are strict aerobes
-Oxidase positive but some arent
-non reactive in API after 24 hours must redo another 24
-resistant to 3rd generation cephalosporins, aminoglycosides, fluoroquinolones
how to see pigment for non fermenters
-take a swab from BA and then you can see it
yellow:
Elizabethkingia, Pseudomonas stutzeri (sometimes tan), Sphingobacterium
Violet:
Chromobacterium violaceum (weak fermenter0
Lavender :Stenotrophomonas maltophilia
Blue green: P aeruginosa
Wrinkled colonies: P. stutzeri, Burkholderia pseudomallei
Odor
Sweet: Alcaligenes faecalis, P. aeruginosa (also paws, or tortillas)
Which GNB are oxidase negative
Acinetobacter
Stenotrophomonas maltophilia
Burkholderia cepacia (w)
Which GNB are non motile
Acinetobacter
Elizabethkingia
Sphingobacterium
what type of org is Pseudomonas aeruginosa
Fluorescent Pseudomonad GroupClinically Significant NonFermenters (NF)
-most commonly isolated non fermentive GNB
-most common cause of nosocomial resp tract infections and is not affected by disinfectants
What clinical conditions can Pseudomonas aeruginosa cause
-bacteremia - poor outlook
-pulmonary disease especially in CF
-uti, wound infections or infections after a burn**
-menigitis is rare can happen in hospitalized syndrome
-hot tub syndrome
-nail bed infections from fake nails
-ear infections in swimmers
-keratitis endopharmitis - contact lens
where is Pseudomonas aeruginosa found
-moist places
-water
-soil
-vegetation
-hospital*** drain, faucet, hot tub
-respiratory equipment
-less common in mucous membranes of humans and animals
what are the virulence factors of Pseudomonas aeruginosa
-Pili
-Capsule
-flagella for motility
-Endotoxin (lipopolysaccharide)
-Exotoxins: proteases, hemolysins, lecithinase, elastase, DNAse, exotoxin A (blocks protein synthesis)
-Cystic fibrosis (CF) patients
Pseudomonas from CF patients are very mucoid and even more resistant to antibiotics
Can form a biofilm
different pseuod for people with CF vs people not with CF
What are lecithin
-brown fatty substance in plants or animals that was first isolated from egg yolk
in CF pt, Pseudomonas aeruginosa converts into mucoid phenotype by making alot of exopolysaccharide alginate. this affects biofilm causing it to be more resistant to tobramycin then a biofilm formed by a non mucoid strain
What is the CMI of Pseudomonas aeruginosa
-BA: BH, flat “football”-shaped, “elliptoid”; with metallic sheen
-MAC: NLF-May or may not have pigmentation
-Fruity grape-like odor
-Growth on cetrimide agar. Cetrimide: acts like a detergent inhibiting most bacteria; enhances production of the two pigments - dark green glow
Pigment production
Seen by naked eye; Wood’s lamp
SOME CAN BE MUCOID AND NH
can smell like tortillas
What the two pigments responsible for the green color of Pseudomonas aeruginosa
Pyoverdin:
-Fluorescent
-Yellow-green or yellow-brown
-Water soluble
Pyocyanin
-Non fluorescent
-Blue, water soluble
-Only produced by Pseudomonas aeruginosa
Pyoverdin + pyocyanin = characteristic green pigmentation
apyocyanogenic (non-pigmented) strains also common
What are the biochemical test results of Pseudomonas aeruginosa
sometimes the tube dont work because pseudo is aerobe and the tubes are anaerobe
-Oxidase positive
-Growth at 42°C -ONLY ONE
-TSI: NA/NC (doesn’t grow at the bottom)
-Growth on cetrimide
-ADH (arginine dihydrolase) +
-Oxidizer**
-Motile (single polar flagellum)**
-Nitrates to nitrogen gas**
-Citrate positive**
-ONPG negative**
-SIM: -/-/+ (at the top only since it needs O2)
-Vitek or API20E, API NE
how do you treat Pseudomonas aeruginosa
-very resistant because of its cell wall impermeability to antibacterial agents
-plasmid mediated resistance
semi synthetic penici, 3rd/4th gen cepha, amioglycosides, carbapenems, fluoroquinolones
What are Pseudomonas fluorescens and putida
-where are they found, growth temp
-what pigment do they produce
Part of the flourescent pseudomonad group
-Low virulence
-found in Respiratory specimens, urine, cosmetics, hospital equipment
-Can grow at 4°C, NOT at 42°C
-Linked to transfusion-associated septicemia
–Produce pyoverdin NOT pyocyanin
-Cannot reduce NO3 to nitrogen gas
-Xylose + = separates them from the other fluorescent Pseudomonads ****
-Gelatin hydrolysed= P. fluorescens + / P. putida -
What is Burkholderia cepacia - Clinically Significant NF
-used to be known as Pseudomonas cepacia, the phytopathogen caused onion bulb rot in plants, foot/jungle rot in humans
-like moist environments and can grow in fluids in hosp and disinfectants like QUATS. Contaminated fluid seed orgs through the hospital
-devastating in pp with CF
-isolated form nebulizers, irrigation fluids , mouthwash, nasal spray
why is Burkholderia cepacia clinically significant
-causes nosocomial infections
-UTI, pneumonia worse for pt with CF and granulomatous disease
-endocarditis in drug addicts
-dermatitis
-highly transmissible in CF pts
-can give a false culture positive if the disinfectant was contaminated
-not commonly found in pt who have proper immune functions
what is CF
Genetic disorder that leads to frequent bacterial -infection in the lung
-airway wall damage
-chronic obstructive lung disease
-Poor gas exchange in the lungs
-cardiac malfunction
if it is inherited
affects secretory glands and mucus sweat glands. Affects lungs, pancreas (clinical name for affecting this site: mucoviscidosis), liver, intestines
Death in CF patients with Burkholderia
What are biochemical IDs for Burkholderia
need heavy colong
-yellow pigment, non-wrinkled on BA
-Gram-negative bacilli
-Oxidase weak positive ** wait longer for reaction
-TSI: NA/NC **
-Oxidative
-Ornithine decarboxylase negative
-ONPG + ***
-Motile – polar flagella
-Nitrates: not reduced (60%), R to nitrites (40%)
-SIM: -/-/+ (at top)
-Citrate: pos (78%)
-Growth and fermentation on BCSA agar
what is BCSA agar
Burkholderia cepacia select agar. Contains CV, polymixin B, gentamicin and vancomycin to inhibit NRF. Contains sucrose and lactose and Phenol red indicator.
What are the Enterobacteriaceae?
family/order of organisms which all share SIX characteristics
Gram negative bacilli
Oxidase negative
Reduce nitrates to nitrites
Ferment carbohydrates
Facultative anaerobes
Grow on MacConkey agar
What is the treatment for Burkholderia cepacia
Resistant to most antimicrobials
Intrinsically resistant to aminoglycosides, polymyxins, many beta-lactams
-Ceftazidime, SXT
-Meropenem
What is Burkholderia mallei
-resp infections in horses - GLANDERS
-doesnt grow in the environment
-rate human transmission (zoonosis) vis skin abrasion
-severe lung infection
-endemic in other countries
-BIOTERRORIST AGENT - WW1
risk group 3
What is Burkholderia pseudomallei
-BIOTERRORISM
-causes meliodosis granulomatous pulmonary disease with lung lesions when you inhale or ingest organism
-endemic in water muddy areas SE asia, Mexico, N Australia
-ability to cause latent infection - vets were known as veit time bombs
–bipolar safety pin staining on GNB
-Wrinkled and dry
What is Acinetobacter species
two most common
habitat
-2ND most isolated non fermenter
-found as A. baumannii complex (very resistant)
and A. lwoffi
-found in nature water, soil and food and in hospital ventilators, humidifiers, catheters
-normal on skin, mucous membrane - pharynx and vagina
What is the clinical significance of Acinetobacter
-colonizer- opportunistic
-seasonal pneumonia in late summer, bronchitis
-it is insignificant if found in vaginal secretions, resp specimen
-because if its resistance need to see how pure it is , type of pt and if it was isolated anywhere else
A.. baumannii increasing resistance to carbapenems: eye infections, corneal ulcerations
What are the biochemical tubes ID for Acinetobacter
non fermenter
-Grows well on MAC; strict aerobe
-GNCB (short plump bacilli can be confused with cocci), similar to Moraxella may look gndc (can be confused with GC in vaginal smears)
-Oxidase negative (GC: oxidase positive)
-TSI: NA/NC
-Oxidizer ****
-Nitrate: Nitrates not reduced
-Non motile **
-Citrate: V (51% pos)
-SIM: -/-/-
-ONPG: neg
A. baumannii – Growth@42C can differieniate from A baumanni with oxidase and A lwoffi because its asaccharolytic
Acinetobacter differentiated from other non fermenters by its oxidase and motility reactions
COCCOID AND PLEOMORPHIC
How is Acinetobacter treated
A. baumannii very resistant; A. lwoffi more susceptible to antibiotics
Acinetobacter baumannii Infections Among Patients at Military
What is Stenotrophomonas maltophilia
-mostly in nature
-3RD most isolated Non Fermentative GNB
-not normal flora but can colonize pts especially those on antimicrobial therapy and also in CF pt
Why is Stenotrophomonas maltophilia clinically significant and where found
–nosocomial infections especially in central venous catheter
-bacteremia, wound , rare meningitis and UTI
-opportunistic
–mostly infect those immunocompromised or on AB for a long time
-multi resistant
-Cotrimoxazole (SXT) is most effective
What are the identifying characteristics of Stenotrophomonas maltophilia
non fermenter
-Yellow-tan pigment on TSA, purple-green halo on sheep blood agar
-MAC: NLF
-Ammonia-like odor
-Similar in characteristics to Pseudomonas but: Oxidase negative**** while pseudo is POS
-TSI: NA/NC
-Nitrate not reduced *
-Oxidizes glucose & maltose (strong)
-Grows at 42C
-Motile **
-Citrate: + (75%)
-SIM: -/-/+ (at the top)
-ONPG: + (70%)
-Catalase +, Gelatin hydrolysed, Lysine +
What is Alcaligenes
where is it found and isolated from
-NF on skin - rarely isolated same as faecalis
-normal in soil, water, pools, water in incubators, resp equipment
What are the identifying characteristics of Alcaligenes
non fermenter
-GNB looks alpha
-Strict aerobe
-May have fruity odor
-Nitrates reduced to nitrites **
-Oxidase positive
-Grows on MAC
-Asaccharolytic no reactions in OF
-Motile by peritrichous flagella
what is Achromobacter xylosoxidans
non fermenter on MAC
-Colonizes CF patients
-Resistant to many antimicrobials
-discoloration on BA
-Motile
-Strict aerobe
-Oxidase positive
What is Pasteurella GNB
-Zoonotic infection
-found in resp tract and GI of domestic and wild animals
-transmission through animal exposure
-opportunistic in cats and dogs part of NF but can cause abscesses through bites
P. multocida – from cat bites
P. canis – from dog bites
What is the clinical significance for Pasteurella and how is it treated
-the type that causes the most infections is P. multocida – from cat bites and it leads to pneumonia, bacteremia, arthritis and osteomyelitis
Treatment
SUS- Penci while other GNB are resistant
RESIS - Ery and Clinda
What are some Biochem indicators for Pasteurella
-Grows well on ordinary media ; NG on MAC**
-Small, translucent colonies with brown discoloration
-GNCB
-Oxidase + (may be slow)
-Catalase +
-TSI: A/Ag **
-Nitrate to nitrites
-Citrate: neg
-SIM: -/+/-
-O-F: F ***
-Easy identification Vitek, API 20E
What is Vibrio and where is it found
cause enteric disease
Family Vibrionaceae
Genus Vibrio
Species:
V. cholerae
V. parahemolyticus,
V. vulnificus
V. alginolyticus
Found
-aquatic environments
Brackish – more salinity than freshwater but not as much as salt water
Estuarine – coastal-free connection to open sea
-Like water temps over 20
-mostly in summer or warm climates
how is vibrio spread
-diarrheal disease due to undercooked fish or shellfish
-spread via contaminated water including pools
-poor hygiene/sanitation
-endemic to India and Bangladesh
-wounds in immunocompromised
Vibrio cholerae O1 (Asiatic or epidemic cholera) – El Tor biotype most virulent: most common strain,
What are the symptoms of vibrio
-need LARGE dose for illness
-severe diarrhea -rice water *** with mucus in it
-org produces enterotoxin (cholera toxin) which affects SI causing it to dump electrolytes and water which causes the diarrhea
-it overwhelms the GI tract absorptive ability
-AB can help to shorten diarrhea and reduce fluid loss
what is Vibrio parahemolyticus and its virulence
-2nd most common Vibrio in gastroenteritis
-#1 cause of summer diarrhea in US, Canada, Japan
-symptoms occur 24-48 hours after eating contaminated seafood like oysters
-sometimes you can have extra intestinal eye and wound infections
-Halophilic likes the coast because it likes salt to grow
Virulence: ?Kanagawa phenomenon
Organism produces heat stable hemolysin able to lyse human RBC in high salt mannitol medium
What is Vibrio vulnificus
where is it found
what can it cause and its risk factors
-Coastal areas including North America
-Wound infection, septicemia (50% mortality)
Cellulitis; rarely, necrotizing fasciitis & multiple organ failure
primary Septicemia from GIT after ingestion of seafood
-death in those with liver disease
Risk factors: patients with liver dysfunction and conditions leading up to increased serum levels of iron.
Patients with organism have a history of some type of traumatic aquatic wound that often presents as a cellulitis.
how does the lab ID Vibrio
-Medical history is very important
-BH on BA
-Curved GNB/“comma”-often seen in direct clinical specimen’s Gram smear); highly pleomorphic
-Motile: polar flagella (most), some peritrichous (V para –so is a bit “spready”)
-Facultative anaerobes (fermenters)
-MAC: NLF (but occ strains may be LF)
-Oxidase positive***
-Reduce nitrates to nitrites
-Citrate: V (50%+), SIM: -/+/+,
-O-F: Fermenter
-Salt loving (halophilic) - (most media OK)
-Vitek, API, Tube biochemicals
Polar sheathed flagella when grown in broth
Peritrichous unsheathed flagella when grown on solid media
What is Aeromonas
Aeromonas caviae
Aeromonas hydrophila
causes enteric disease
investigation based on history and symptoms
Aeromonas
-same as pseudo found in water or moist places sink, faucets and can cause nocosomial infections
-seasonal prefers warm months
Aeromonas caviae
-more common than A. hydrophilia
-gastrointestinal
Aeromonas hydrophilia
-septicemia
-cellulitis and wound infections -due to recent water traumatic exposure aka after tsunami
-UTI, liver, ear and endocarditis
-acute diarrhea similar to Campy and Shig
How will the lab ID Aeromonas
Similar to Enterobacteriaceae its facultative
-similar to vibiro
-MAC: LF or NLF; TSI: A/Ag or NA/A
-GNB (straight)
-Oxidase positive ** good indicator that it isnt Enterobacteriaceae
-Motile- single polar flagella
-O-F: Fermentative
-Most are indole +
-BH or NH
-Nitrate: reduced to nitrites
-SIM: -/+/+
-ONPG: pos
-Can be misidentified as Vibrio by some systems
-Does not grow in 6% NaCl differentiates between vibrio
What is Plesiomonas
where is it found and what does it infect
-from greek word Neighbour
-P. shigelloides only species
-Habitat: surface waters, soil
Commonly infects many warm blooded and cold blooded animals
Dogs, cats, pigs, vultures, turtles, snakes, lizards
What is the clinical significance of Plesiomonas
-Gastroenteritis -mild, watery diarrhea after ingestion of contaminated water or unwashed food
Uncooked seafood, traveler’s diarrhea
-(Few) Extra-intestinal infections
-Occupational exposure (animal contact)
-septicemia, neonatal meningitis, cellulitis, septic arthritis, acute cholecystitis
How does the lab ID Plesiomonas
-Short, rounded Gram negative bacilli
-Grows on BA, MAC ( most LF)
-Non-hemolytic on BA
-Oxidase positive
-Motile monotrichous or lophotrichous (1-5 polar flagella)
-Indole positive
-Fermentative (delayed)
-INO well on API +, Aeromonas – (differentiating)
-Does not grow in 6% NaCl
VIBRIO WILL GROW IN 6% NACL BUT AERO AND PLESI WILL NOT
What is Campylobacter
where is it found
what does it cause
what types are isolated
C. jejuni, C. coli, C. lari
-microaerophilic
-leading bacterial cause of gastroenteritis
-water, bloody diarrhea 2-5 days after ingestion
-uptake during summer bbq season - uncooked foods
found in
-GI tract of animals - farm animals
-reproductive organs of animals can cause animal abortions
what is the mode of transmission of Campylobacter
-needs low infective dose
-through contaminated milk, food or raw chicken, improperly pasteurized milk (outbreak)
-DOES NOT multiply in food
-through lab workers because of the low dose -easier to get
-enterotoxin and cytotoxin causes diarrhea
how does the lab ID Campylobacter
media, temps and incubation
-gram right from stool -direct because there is background staining
-motile- darting from side to side
-culture must be done in 2 hours of collection or needs to transported in Cary Blair medium
-microaerophilic 5% O2 or less must use a Campy pak to introduce CO2 and Nitrogen
-will grow at 42-43 or even body temp and incubate for 48-72 hours.
-need BAP, Campy-BAP, Skirrow’s or other selective medium (from stool specimens) which may contain horse blood and AB like vanco, trimethoprim, polymyxin, cephalothin, amphotericin B
What are the CMI and biochemical ID for Campylobacter
-NH, pinky-grey, “wet” or mucoid, spread along the streak lines (“puddles”)
Screening Tests
-Characteristic Gram stain -GULL WING GNB
-Oxidase positive
-Wet prep- motile –single, polar flagella (darting motility)
-HIPPURATE POSITIVE JEJUNI
-Some labs report C.jejuni/coli but important to identify species for epidemiological purposes (latex agglutination or hippurate hydrolysis)
-C. jejuni most commonly isolated
-lari is differeniated by jejuni because it is R to Nalidixic acid while jejuni is R
-no susceptibility because it is a self limiting infection
What is Helicobacter pylori
where is it found
-found in mucus secreting epithelial cells in stomach NOT INTESTINES causing gastritis, duodenal ulcer disease, gastroenteritis and can cause gastric carcinoma
How is Helicobacter pylori ID in the lab
what kind of methods
–microaerophilic
-Urease breath test where CO2 is released if present , collect breath samples in an hour
-Ingest labeled urea - detected in urine
-Serology mostly for epidemiological studies , ELISA for IgG and latex agglutination
-AG detection in stool
-Endoscopy and culture -INVASIVE with gastric biopsies, aspirates, brushing. Make sure sample is kept in saline and must be sent to lab in 3 hours but can be 5 if kept at 4 degrees
what is the CMI for Helicobacter pylori
-Small, gray, translucent, weak beta-hemolysis
-Gram: pale staining, curved Gram negative bacteria “gull-wing” and “U” shapes
-Oxidase +, catalase +, rapid urease +
-can also be stained using acridine orange
-plate on BHI and Skirrows media with vac, poly B and Trimeth and incubate at body temp for 3-5 because it is a slow grower
What the two groups of GNB
Group 1- Oxidative or asaccharolytic, oxidase + (most) and nitrates reduced to nitrites, to nitrogen gas or not at all’ NON FERMENTER
Group 2- Fermentative but oxidase positive
how can GNB be ID through O/F test and oxidase test
O/F test: most nonfermenters (oxidative or no action)
Oxidase test: oxidase + and its fermenter its NOT Enterobacteriaceae
Useful preliminary test
Although some may be oxidase neg – they will differ in other tests typical of Enterobacteriaceae
TEST FROM BAP OR CHOC ONLY NOT MAC because the sugars interfer
how do we ID GNB that are not Enterobacteriaceae
on gram and TSI
Gram Stain
Most are similar to Enterobacteriaceae
Some GNCB - Acinetobacter, Pasturella
Some curved or comma-shaped - Campylo
TSI
-Enterobacteriaceae & fermenters: A/A or NA/A
-Oxidative and Nonfermenters: NA/NA or NA/NC (no change or no reaction) good indicator that its not an Enterobacteriaceae might be oxidative or asycrolotic
-First clue that you are dealing with a nonfermenter
Rarely produce H2S
how do we ID GNB that are not Enterobacteriaceae
on MAC and BA
MAC-NG or ppt
Blood Agar
- pigmented Elizabethkingia and P aeruginosa
Most grow well on BA but some require supplements (e.g. Campylobacter, Helicobacter)
how do we ID GNB that are not Enterobacteriaceae
through Nitrate and Motility
ALL Enterobacteriaceae reduce nitrates to nitrites
Nitrate test
These organisms may:
Not reduce nitrates
Reduce nitrates beyond nitrites to gas
Reduce nitrate to nitrites
Motility test
-Often strict aerobes - stab motility (e.g. SIM) useless as organism cannot grow further down
-May see spreading across top (from liquid on surface of media)
-Wet prep more reliable test of motility because it helps to determine motility if strict aerobe or facultative
What is a flagella stain
-Motile Enterobacteriaceae are peritrichous - flagella surrounding
-“Other gnb” bacteria more often one or more polar flagella (one or more on one end, or one on each end)
-Location and number is frequently diagnostic
75% of all nonfermenters will be identified as
Pseudomonas aeruginosa (60% of nonfermenters isolated)
Acinetobacter spp.
Stenotrophomonas maltophilia
Campylobacter - number 1 stool pathogen
