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68 Cards in this Set
- Front
- Back
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Common characteristics of NFB
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- Non-fermentative bacillus
- Large pleiomorphic GNR's - Grow well on SBA - Mainly non fastidious - Cause opportunistic infections in compromised hosts, and nosocomial infections - Clinical sources are wounds, UTI, blood, CSF |
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Oxidase Pos NFB's
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- Pseudomonas
Alcaligenes Chryseobacterium |
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Oxidase Neg NFB's
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Strenotrophomonas
Acinetobacter |
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Top 3 clinical NFB isolates
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1- Psuedomonas aeruginosa
2- Acinetobacter spp. 3- Strenotrophomonas maltophilia |
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O/F media components
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1% glucose
1% maltose 0.2% peptones (important because NFB prefer peptones) Bromthymol blue |
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Purpose of O/F media
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Oxidation of sugars produces small amounts of acid that bromthymol blue detects
This test is designed to tell you if organism is: oxidizer = saccharolytic (uses aerobic respiration) non-oxidizer = non-saccharolytic or fermenter= enteric (you messed up) |
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When and why would you do an oxidase sweep
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- Do it when you suspect a GNR on an SBA or MAC
- done to detect oxidase positive NFB specifically Pseudomonas, and to a lesser extent Alcaligenes, and Chryseobacterium |
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Pseudomonas aeruginosa infections
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- Infection of burn patients (causes green color)
- causes nosocomial urinary tract infections - causes infection in 80-90% of cystic fibrosis patients - causes necrotizing skin rash from hot tub |
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Worry's about burn patients and infectious organisms
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- If patient survives 3-4 days after burn the big concern is skin infections from;
1- Pseudomonas aeruginosa 2- S. aureus (especially MRSA) -Flowers are not allowed in burn ward because P. aeruginosa is common is soil and plants |
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What causes CF and what areas of the body does it affect
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Caused by gene mutation inherited from parents
- affects sweat and mucus glands which affect the intestines and lungs - the mutation stops the production of protein that is responsible for moving chloride ions across cell membranes |
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What is the CF gene
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CFTMR- cystic fibrosis transmembrane regulator
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P. aeruginosa and CF
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80-90% of CF patients have P. aeruginosa infections of the lungs
- Recurring P. aeruginosa infections and the inflammation that accompanies it gradually damage the lungs, causing respiratory failure, which is the leading cause of death among CF patients |
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Why is P. aeruginosa a serious nosocomial pathogen
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1) well adapted to harsh environment. Will survive long periods of time in dust or plain distilled water
2) Prevalence. Ubiquitous in soil and dust and will reappear in a place that may have been sterile a few hours previously 3) Highly resistant to anti-microbials. has a mutation in the cell wall porin proteins 4) Once established in tissue it is extremely difficult to eradicate |
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P. aeruginosa pigment producer and colors
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1- Pyocyanin- gives green color on mac and produces a oil slick sheen at 48 hrs
2- Fluroescein- light brown color 3- Pyorubin- light brown |
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P. aeruginosa characteristics
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- SBA- large flat, mucoid ground glass, Beta hemolytic
- oxidizer, glucose pos, maltose neg - grape or corn tortilla odor ( 2- amino acetophenone produces this smell) |
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Virulence factors of P. aeruginosa
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- adhesins
- alginate production - exotoxin A - Exoenzyme S - Elastolytic activity - Phopholipase C - Pyocyanin - Antibody resistance |
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Explain adhesins
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Mediate attachment to host epithelial cells( pili and nonpilus adhesins), enhance pili adherence (production of neuraminidase)
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Explain alginate production
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Forms mucoid layer that protects bacteria form phagocytosis and facilitates adherence to host cells
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Explain exotoxin A
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Inhibits host protein synthesis and produces tissue damage
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explain exoenzyme S
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inhibits host protein synthesis and interferes with phagocytic killing
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Explain elastolytic activity
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degrades elastin, with direct damage to lung tissue and vessels
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Explain phospholipase C
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Mediates tissue damage
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Explain pyocyanin
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mediates tissue damage through production of toxic oxygen radicals
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Other significant species of Puedomonas
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1- Pseudomonas fluorescens (no growth at 42 C where P. aeruginosa does grow at 42 C
2- Burkholderia cepacia- most often associated with pneumonia in CF patients 3- Pseudomonas stutzeri- very wrinkled colonies |
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Acinetobacter characteristics
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- Mac lac neg, produces purple pigment
- oxidase neg, catalase pos - A. baumii is glucose pos maltose neg - A. lwoffi is glucose neg and maltose variable - non-motile |
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Strenotrophomonas characteristics
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3rd most common NFB
- growth on MAC - oxidase neg, catalase pos - Glucose pos, maltose pos |
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Alcaligenes characteristics
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- Growth on MAC, dry feathery colonies
- Oxidase pos, catalase pos - Non-oxidizer - glucose neg, maltose neg - Sweet apple smell |
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Chryseobacterium characteristics
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- Poor to no growth on MAC
- oxidase pos, catalase pos - O/F rxns variable |
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Why is O/F media used instead of the slant of a TSI to detect oxidation by NFB
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- O/F media has a much more sensitive pH indicator
- NFB's cant oxidize the lactose or sucros on the slant, so the 0.1% glucose in TSI is used up quickly and the slant reverts to K - The lower % of peptones keeps the small amount of acids produced by the oxidation from being overshadowed by the breakdown of peptones |
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List the Fastidious GNR genera
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Haemophilus
Bordetella Campylobacter Legionella Pasteurella Eikenella Bartonella |
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Fastidious GNR characteristics
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- Won't grow on MAC, bile inhibits it
- Tiny gram negative pleiomorphic rods - Fastidious bacteria |
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Areas where H. influenzae is normal flora
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- Upper respiratory tract
- conjuctiva |
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Virulence factors of H. influenzae
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- Capsule (H antigen) 6 capsule serotypes A-F
- IgA protease, cleaves secretory IgA |
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Vaccines for H. influenzae
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HIB vaccine
Capsular material of Type B |
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Explain how organism aquired its name
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During an epidemic isolated small GNR was found in the lungs of patients who died from influenza
- this was H. influenzae which is a sequela disease |
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Explain X and V factors
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X= hemin
V= NAD+ |
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Organisms that require X and V
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H. influenzae and H. haemolyticus
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Organisms that require only X
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H. ducreyi (STD causes chancroid)
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Organisms that require only V
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H. parainfluenzae
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Organisms that dont require X or V
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H. aphrophilus
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X and V plating media
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Meuller hinton agar on Kirby bauer plate
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List the infections and diseases associated with Haemophilus spp.
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Pneumonia
Croup (baby trachea and bronchi) Meningitis (H. influenzae type B) Septicemia EPIGLOTTITIS (about the only organism that causes this) eye and ear infections |
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Cause of pink eye
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H. influenzae biotype aegypticus and S. aureus
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Causes of otitis media
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#1- H. influenzae
#2- S. pneumoniae #3- Morhaxella catharallis |
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Explain the satellite phenomenon and organisms involved
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H. influenzae can't grow on SBA because V factor is not available
-X factor is available in the SBA due to some lysed RBC's -H. influenzae can grow in proximity to 1) S. aureus 2) S. pneumoniae 3) Neissieria spp. - These organisms will produce V as a metabolic byproduct and H. influenzae will produce small satellite colonies around the V factor producing organisms |
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Explain whooping cough
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- AKA pertussis, used to be called "100 day cough"
-Caused by Bordetella pertussis - coughing spells - Whoop sound - vomiting, apnea, and cyanosis - Rapid fire coughing spells - can last 5-15 minutes at a time |
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Bordetella toxins
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- Pertussis toxin (exotoxin) and tracheal cytotoxin
- the bacteria attach to ciliated cells in trachea and secrete these toxins which destroy the cells |
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Incubation stage of whooping cough
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7-10 days
- bacteria multiply but no symptoms are apparent |
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Catarrhal stage of whooping cough
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- signs and symptoms that resemble common cold
- lasts 1-2 weeks - bacteria are MOST ABUNDANT and patient is most infectious |
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Paroxysmal stage of whooping cough
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- Begins as ciliary action of tracheal cells is impaired
- WHOOP SOUND |
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Convalescent stage of whooping cough
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Bacteria number decreases
- Cilia is restored - Severity and frequency of cough diminishes -lasts 3-4 weeks - Secondary bacterial infections occur (Staph or Strep) in the damaged epithelium and may lead to bacteremia, pneumonia, seizures, and encephalopathy |
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Bordetella culture sight and transport media
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-Nasopharyngeal swab
- organism is extremely sensitive to drying so transport media is Regan- lowe media which has; -Horse blood - charcoal - cephalenn |
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Primary plating media for Bordetella
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1) Bordet- Gengou agar (SBA with potato and glycerol extract)
2) CHB- same as regan lowe |
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Appearance of Bordetella after 3-4 days
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you get colonies known as "droplets of mercury"
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How is Bordetella detected
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DFA- direct fluorescent antibody
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Vaccine for Bordetella
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DTap- diptheria, tetanus, acellular pertussis
-Old vaccine was DTP, but was switched because acellular pertussis had less side effects |
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Characteristics of Bordetella bronchioseptica
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Occasional respiratory pathogen
- non fastidious- recoverable with routine culture media |
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Campylobacter jejuni characteristics
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Campylo= curved
- Gram negative CURVED rod - most common cause of gastroenteritis in the U.S. - one of the BIG FOUR gastrointestinal pathogens - found in GI of poultry, sheep and cattle - 90% of raw poultry products are contaminated with campylobacter - only takes 500 organisms or less to start an infection |
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C. jejuni lab identification
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Specimen is Stool
- requires special Campy agar with 10% sheep RBC's and 4 anti-microbials - organism is microaerophilic and capnophilic- grows in increased CO2 (won't grow in our CO2 incubator) - Growth at 42 C - Darting motility due to singly polar flagella |
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name the BIG FOUR gastrointestinal pathogens in the US
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1- Campylobacter
2- Shigella 3- Salmonella 4- Giardia lamblia |
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Explain Legionella pneumophilia and its disease
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- Fastidious GNR that causes Legionnaries' disease aka legionellosis
- exists were water collects and can live and grow within the protective confines of waterborne protozoa - becomes airborne in wind gusts and breezes - Legionella outbreak in michigan in 1968 was known as PONTIAC FEVER |
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Characterstics of Legionella pneumonia itself
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-found in water supplies
- infects smokers and immunocompromised - need special BYCE agar (Buffered charcoal yeast extract) |
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How is L. pneumophilia detected
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DFA from sputum and pulmonary secretions
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Pasteurella multocida
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- Aquired from scrathes and bites from dogs and cats
- if wound won't heal it's most likely infected with P. multocida |
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Pasteurella multocida lab ID
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-No growth on MAC, will grow on SBA
- Weak or Sick butt rxn on TSI - Gram negative pleomorphic coccobacillus |
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Eikenella corrodens characteristics
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- Normal oral and GI flora
- found in human bite infections and fist fight injuries - found in bone abscesses of face and neck |
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Eikenella corrodens lab ID
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- No growth on MAC, small colonies on SBA
- causes pitting of agar surface - oxidase pos, catalase neg - odor of bleach - non-oxidizer |
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Bartonella henslae characteristics
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- causes cat scratch fever
- humans aquire through cat scratches and bites, and from fleas that transmit it from cats |
