Special Pathogens Flashcards
1
Q
Pseudomonas Clinical Significance
A
- Illness
- UTI
- Septicemia - [hematologic disorders]
- Respiratory disease – [CF patients]
- Now COPD (4th leading cause of death in US)
- Wounds/sepsis – [thermal injuries]
- Pulmonary disease – [intubation, immunocompromised]
- Osteomyelitis – [heroin addicts, long-term iv therapy, previous surgery]
- Sources
- Sinks, traps
- Soaps, solutions
- Water faucets, aerators
- Inhalation equipment
- Catheters
- Sponges, mops
- Hospital food
- Flowers
- Personnel: hands
- Antiseptic creams
- Iodine solutions
- Ophthalmic solutions
2
Q
Pseudomonas ID
A
- Produces a grape-like or tortilla odor on BAP
- Elaborates strong β-hemolysin
- Produces many different pigments:
- Pyocyanin (blue)
- Pyoverdin (yellow)
- Pyorubin (red, brown)
- Produces many different colony types on BAP or common basal media:
- Classic or typical
- Rough or rugose
- Coliform-like
- Mucoid
- Dwarf
- P. Aeruginosa only produces pyocyanin a way to separate
- Biochem
- Indole -
- Glucose, OFBM +
- Fructose, Xylose, Mannitol +
- Lactose, Sucrose, Maltose -
- H2S-
- Urease +
- ADH +
- ODC, LDC -
- ONPG -
- Lipase, gelatinase +
- DNase -
- K/NC-
- oxidizer
3
Q
Pseudomonas Species ID
A
- Ps. stutzeri
- Maltose +
- ADH -
- Ps. mendocina
- Maltose -
- ADH +
4
Q
Acinetobacter Clinical Significance
A
- Illnesses
- Pneumonia
- Bloodstream infections
- Wounds
- UTI
- Meningitis
- Risk Factors
- Prolonged stay in ICU
- Prior antibiotic exposure
- Mechanical ventilation
- Use of a CVC (Central Venous Catheter)
- Hemodialysis
- Medical treatment practices
- Indwelling devices
- Hydrotherapy (burns)
- Exposure to contaminated medical equipment
- Ac. baumannii – Pneumonia
- Ac. baumannii - Septicemia
5
Q
Acinetobacter ID
A
-
Characteristic
- Smooth, sometimes mucoid, grayish white colonies
- Non-pigmented; some strains produce a “fish-like” odor
- Ac baumannii cplx grows well on common laboratory media @ 37°C
- Other species produce translucent colonies; growth variable on media
- Biochemically a unique organism not easily confused with other NFGNR
- Can be extremely pleomorphic and not presenting as a gram-negative rod
- Sometimes appears as cocci
- Can stain Gram-variable
- Reactions
- Oxidase
- -
- Indole
- -
- Motility
- -
- Glucose
- V
- Lactose, Xylose
- V
- Mannitol, Sucrose
- -
- Urease
- V
- Nitrate reduction
- -
- LDC, ODC, ADH,
- -
- ONPG
- -
- DNase
- -
6
Q
Acinetobacter Species ID
A
-
Trait for Ac. baumannii Cplx from Other
- Other Grps
- Growth at 41°C
- +
- -
- +
- Gelatinase
- -
- V
- Hemolysin
- -
- V
- Glucose, acid
- +
- V
- L-phenylalanine
- +
- -
- trans-Aconitate
- +
- -
- Suscp: Pen, Chl
- -
- V
7
Q
Oxidative-Fermentative (OF) test
A
- Increased acid detection over broth media
- semisolid agar (0.2 – 0.3%), enhances acid visualization
- Basal medium contains 1% CHO, 0.2% peptone (1:5 ratio)
- low peptone, decreases oxidative products from a.a. that may neutralize acids
- increased carbohydrate = increase acid
8
Q
Hugh-Leifson (OF Difco MDL)
A
- bromothymol blue
- yellow = acid
- blue = alkaline
9
Q
King’s OF
A
- phenol red
- yellow = acid
- red = alkaline
10
Q
Yersinia Clinical Significance
A
- Pneumonic plague
- Bubonic plague
- Septicemic plague
11
Q
Yersinia ID
A
- Characteristics
- “Large” Gram negative rod
- Safety Pin Gram stain
- fried egg on SBA
- Will grow on routine culture media SBA, CHOC, and MAC
- Resembles other Enterobacteriaceae EXCEPT grows faster at 25 o C or RT than at 37 o C
- KEY BIOCHEMS
- Oxidase NEG
- Urease NEG
- Indole Neg
- Catalase POS
- Non Lactose fermenter on MAC
12
Q
Francisella tularemia Clinical Significance
A
- “Rabbit Fever” & “Deer fly
- F. tularensis : causative agent of tularemia, acute & fatal illness in animals & humans
- HIGHLY infectious (10 organisms can cause disease!)
- Notorious reputation for lab acquired infections
- Human infections caused by:
- Arthropod bite
- Handling infected animals
- Inhalation of infectious aerosols
- Ingestion of contaminated food or water
- Tularemia symptoms depend on virulence of bacterial strain & route of infection.
- Symptoms of all forms of tularemia typically include fever, headache, body aches, and malaise.
- Symptoms usually develop within 3 to 5 days of infection
- Incubation period can be 1 14 days.
13
Q
Francisella tularemia ID
A
- Very tiny Gram-negative coccobacilli (counterstain poorly - safranin)
- Strict aerobes
- Weakly catalase +
- Urease –
- Oxidase -
- Non-motile
- Non-spore forming
- Metabolize limited number of sugars (acid produced w/o gas)
- Glucose, maltose, sucrose, glycerol
- Unique cellular fatty acids
- In vitro growth enhanced by cysteine supplementation
- A few key differences separate species
- Oxidase, growth in NB w 6% NaCl , optimum growth temps, sugar
utilization, virulence
- Oxidase, growth in NB w 6% NaCl , optimum growth temps, sugar
14
Q
Stenotrophomonas maltophilia Clinical Significance
A
- Illnesses
- Septicemia
- Respiratory tract
- Urinary tract
- Skin and soft tissue
- Bone and joint
- Endocarditis
- Meningitis
- Gastrointestinal
- Risk Factors
- Neutropenia or cytotoxic chemotherapy
- Presence of a central venous catheter (CVC)
- Prolonged hospitalization; admission to ICU
- Mechanical ventilation or tracheotomy
- Previous exposure broad-spectrum antibiotics
- Extremely resistant bacteria to antimicrobials
15
Q
S. maltophilia ID
A
- Laboratory Characteristics
- Colonies develop a lavender-green color on BAP
- Produces a brown – tan pigment
- Growth on BAP accompanied by strong odor of ammonia
- Grows on most common media: MacConkey
- Biochemically a unique organism not easily confused with other NFGNR
- Reaction
- Oxidase
- -
- Indole
- -
- Glucose, Fructose, Lactose, Maltose
- +
- Mannitol
- -
- H2S, urease
- -
- LDC
- +
- ODC, ADH
- -
- ONPG
- +
- Lipase, gelatinase
- +
- DNase
- +
16
Q
Elizabethkingia Clinical Significance
A
- E. meningoseptica (Chryseobacterium meningosepticum)
- neonatal meningitis
- neonatal septicemia
- Elizabethkingia miricola
- septicemia
- Elizabethkingia anophelis
*
17
Q
Elizabethkingia ID
A
- General Properties
- Gram-negative aerobic rods
- Non-motile
- Growth range 28 - 37°C
- Catalase and oxidase-positive
- Casein, esculin, and gelatin are hydrolyzed
- E. anophelis
- Gram-negative aerobic non-fermentative rods
- Some strains exhibit slight yellow pigmentation
- Non-motile
- Biochemicals:
- Oxidase +
- Catalase +
- Indole +
- Cannot be biochemically separated from E. meningoseptica
18
Q
BRUCELLA Significance
A
- Major human pathogens
- B. abortus (cattle, cow, bison)
- B. canis ( Dog)
- B. melitensis (goat and sheep)
- B. suis ( Swine)
- Other Brucella species
- B. neotomae (wood rat)
- B. ovis ( Ram)
- “B. maris ” (marine animals), “B. pinipediaepinipediae”, “ B. cetaceae ”
- Clinical Syndromes
- Systemic
- CardioCardio-vascular
- Cutaneous
- GastroGastro-intestinal
- Neurological
- OsteoOsteo-articular
- Reproductive
- Respiratory
- Acute
- Fever, malaise, headache, anorexia, arthralgia, myalgia , and back pain
- Within 1 to 4 weeks after exposure
- Subchronic (undulant)
- Low temperature in morning followed by rising
- temps in the afternoon and evening
- Within 1 year after exposure
- Arthritis and epididymoorchitis may occur
- Chronic
- Depression, arthritis, and chronic fatigue syndrome
- Around 1 year after exposure
- Transmission
◦ Direct contact thru broken skin, eyes
◦ Inhalation
◦ Ingestion
◦ Approximately 2% of all reported cases are acquired
in the laboratory (chances of acquiring from lab
exposure varies 30 30-100% and depends on various
factors)
19
Q
Brucella ID
A
- Characteristics
- Strict aerobes (oxidizers), some require CO 2
- Grows on SBA and CHOC, do not grow on MAC or EMB
- Smooth, raised, non-hemolytic, and translucent colonies
- Nonspore
- Nonspore-forming, gram gram-negative coccobacilli
- Nonmotile, non-encapsulated, intracellular pathogens (can reside in mononuclear phagocytic cells)
- Gram -
- Intracellular
- Nutritionally fastidious
- -Very slow grower (plates should be beheld for 4 days before reported negative)
- coccobacillus
- faintly staining
- small
- Biochemical tests
- Oxidase—positive
- Catalase—positive
- Nitrate reduction reduction-positive
- Urease—positive within 2 hours
- Hydrogen sulfide (H H2S) production
- X and V factor testing maybe helpful in ID (negative for X and V
- Serologic testing preferred along with history and disease status to diagnose brucellosis.
20
Q
*Burkholderia spp.
Mellioidosis/ Glanders*
Significance
A
- Major respiratory pathogen in cystic fibrosis patients (B. cepacia complex)
- CDC Category B potential bioterrorism agents (B. mallei, B. pseudomallei)
- Respiratory disease - CF patients
- Septicemia
- Soft tissue infections
- Ocular infections
- Infection with BCC often occurs after lengthy colonization with
Ps. aeruginosa
21
Q
Burkholderia mallei
A
- Glanders is an infectious disease that is caused by the bacterium Burkholderia mallei. Glanders is primarily a disease affecting horses, but it also affects donkeys and mules and can be naturally contracted by goats, dogs, and cats.
- Direct skin or mucous membrane contact with infected animal
tissues
• Inhalation of infectious aerosols – laboratory-acquired infection
• The incubation period = 1 to 14 days
• Occupational Infections
• Individuals who work with horses, mules, donkeys
• Laboratory workers - • Often manifests as:
• pneumonia,
• bronchopneumonia
• Lobar pneumonia with or without bacteremia
22
Q
Burkholderia – Laboratory
Characteristics
A
- Smooth and convex in early growth, with some species
- developing umbonate wrinkled colonies with age
- Pigmentation varies ranging from non-pigmented species
- (mallei) to noted yellow pigmentation in others (cepacia, gladioli)
- Burkholderia grows well on BAP or MacConkey agars; variable to
- no growth on SS and cetrimide
*
23
Q
B. cepacia & B. gladoioli: Biochemical
Properties
A
24
Q
B. pseudomallei Technical
Clues
A
- Gram-negative aerobic rods
- Characteristic slow to moderate growth on SBA and MAC
- Oxidase positive
- Motile
- Catalase positive
25
Q
B. mallei Technical Clues
A
- • Gram-negative coccobacilli
- • Characteristic very slow growth on SBA and little if any growth
- MAC
- • Oxidase variable
- • Non-motile
- • Catalase positive
26
Q
Bordetella pertussis ID
A
- B. pertussis is small GNCB
- B. parapertussis and B. bronchiseptica are more rod shaped
- Bordetella species do not gram stain well
- Safranin counterstain should be extended for better visualization
- Bordet-Gengou (BG) is a potato-based agar with sheep blood and glycerol
- Starch neutralizes toxic materials present in specimen
- Does not contain peptones because these may be inhibitory
- Cephalexin, methicillin, or oxacillin may be added for selectivity
- oShelf life 5 days
- Regan-Lowe media contains charcoal and horse blood
- Available as semisolid transport/enrichment media and solid media
- for isolation
- May contain cephalexin and/or amphotericin B for selectivity
- Shelf life 4-8 weeks
27
Q
Bordetella pertussis Significance
A
- Whooping cough
- Respiratory infection characterized by paroxysmal cough, posttussive vomiting, and inspiratory whoop
- Incubation period: 7-10 days; range 5-28
- 3 stages of disease
- 1.Catarrhal: nonspecific cold symptoms (1-2 weeks)
- 2.Paroxysmal: severe coughing spells that end in an inspiratory whoop (2-6 weeks)
- 3.Convalescent: decreasing frequency of coughs, though viral infections can trigger paroxysms (1-12 weeks)
- Cough may last more than 10 weeks
- Complications include pneumonia, rib fractures, incontinence, syncope
28
Q
Haemophilus ID
A
- Small GNRs or coccobacilli, pleomorphic, X factor independent spp. appear as long filaments
- Facultative anaerobes
- Non motile and non spore formers
- Oxidase positive (in contrast to Enterobacteriaceae
- Catalase and nitrate positive
- All require preformed growth factors found in blood
- X factor heme/hemin (protoporphyrin IX) or
- V factor NAD or NADP or
- X and V both
- With the exception of H. ducreyi and H. aphrophilus,
- all need V factor
- On BAP grow as satellite colonies around S. aureus
- β-hemolytic on horse, bovine or rabbit blood but
- NOT on she
- ep blood (H. hemolyticus, H.
- parahemolyticus and H. pittmaniae)
- Growth produces pungent or “mouse-nest” smell
- Increased CO2 (5-10%)
- Capsule Virulence factor
- Serotypes a-f
- Haemophilus influenzae serotype b (Hib)
29
Q
Haemophilis General Characteristics
A
- H. influenzae type b (meningitis, cellulitis
- epiglottitis, pneumonia, septic arthritis)
- H. aegyptius (Koch-Weeks bacillus, pink eye)
- H. influenzae biotype aegyptius (Brazilian purpuric fever)
- H. parainfluenzae (endogenous)
- H ducreyi (chancroid)
- H. aphrophilus (HACEK, endocarditis)
- Haemophilus – Blood loving
- Require X and V factors found in blood X factor is hemin, hematin
- V factor is nicotinamide-adenine dinucleotide (NAD)
- All para species – require only V factor
- Haemophilus parainfluenzae
- Produces X factor, requires V factor
- H. aegyptius causes conjunctivitis
30
Q
Virulence Factors:
H. influenzae
A
- Capsule
- Serotypes a a-f
- IgA protease
- Cleaves IgA on mucous membranes
- Outer membrane proteins and lipopolysaccharide ( Not well defined
- Antibody to these proteins is somewhat protective
- LPS paralyzes the cilia
- Can’t clear the lungs
- Adherence
- Pili and other structures
31
Q
Legionella General Characteristics
A
- Legionnaire’s Disease
- Route of infection: aerosol
- Symptoms: Cough, shortness of breath, fever, muscle aches, headaches
- Onset: 2 -10 days post- exposure
- Disease: Pneumonia
- Isolation of agent: Possible
- Outcome: 5% - 40% mortality
- Pontiac Fever
- Route of infection: aerosol
- Symptoms: Fever, muscle aches
- Onset: 24 – 72 h post-exposure
- Disease: Flu-like illness
- Pathogenicity Factors
- Biofilms
- Replication within host phagocytic cells
- Others: iron acquisition, cytotoxins
- Monoclonal subtyping of L. pneumophila
- serogroup 1
- MLST – flaA, pilE, asd, mip, mompS, proA genes
- AFLP
32
Q
Legionella ID
A
- Motile, gram-negative rods
- Asaccharolytic, amino acids used as energy source
- Obligate aerobe
- Nutritionally fastidious, L-cysteine dependent
- Optimal growth @ 35
- Growth enhanced by iron, humidity
- If you pretreat sample, use low pH KCL-HCL buffer, 4 mins, at room temperature or heat at 50°C for 30 mins
- Use selective and non-selective media:
- VAP or BMPA
- BCYEα
- Incubate at 35°C, humidity, CO2
- (2-5%)
- Read days 1-5 and day 14
33
Q
Moraxella catarrhalis General Characteristics
A
- Causes acute, localized infections such as otitis media, sinusitis, and bronchopneumonia
- Causes a large amount of lower RT infections in elderly patients with COPD
34
Q
Moraxella catarrhalis ID
A
- Cultured on blood and chocolate agar
- White/grey colonies, waxy surface
- Hockey puck test – able to push the colony across the plate
- Specimen types include: inner ear fluid, sputum, and blood
- Key
- Not able to ferment glucose, sucrose, maltose, and lactose
- Positive DNase
- Oxidase Positive
- Nitrate Positive
- M. catarrhalis is often mistaken for N.catarrhalis
- M.catarrhalis strains can tolerate lower temperatures and will grow well at 28˚C
35
Q
GENUS NEISSERIA ID
A
- GN coccal or diplococci, aerobic, non-motile
- Growth optimal at 35° with humidity, CO, stimulates growth or maybe obligate for initial isolation
- Oxidase positive
- Difficult to separate. Usually ID as “Nesseria species” unless isolated from systemic source or pure culture
- Choc or BA if sample sterile
- Modified Thayer-Martin if non sterile sample
36
Q
Neisseria General Characteristics
A
- Neisseria Gonorrhea
- Neisseria Menigiditis
37
Q
Bacillus Anthracis General Characteristics
A
- Colony on SBA at 35°C, 18-24hr
- Flat or slightly raised, grey to white
- Undulate edge may show curling resembling a “Medusa head”
- Surface has “ground glass” appearance
- “Tenacious” or “sticky”
- Non-hemolytic
- Large Gram-positive rod
- Usually non-encapsulated, often in long chains
- Cells are more easily decolorized with age
- Oval spores, central to sub-terminal, with no swelling of cell
- Rapidly growing, flat, “ground-glass” colonies on SBA
- Large Gram-positive, aerobic rods
- Non-hemolytic
- Non-motile
- (Catalase positive)
38
Q
Bacillus ID
A
39
Q
Bacillus Anthracis Diseases
A
- Inhalation
- Gastrointestinal
- Cutaneous
40
Q
Listeria monocytogenes General Characteristics
A
- 32% Neonatal sepsis and meningitis
- 31% Febrile gastroenteritis
- 26% Sepsis in compromised hosts
- Motility described as tumbling end over end is viewed microscopically in a hanging drop preparation and umbrella like when viewed in tube cultures grown at room temperature
- Facultative anaerobes
- Optimum growth temperature
- 30-37°C
- Can grow at 4°C
41
Q
Listeria Monocytogenes ID
A
- Gram positive, nonsporeforming, short rods
- Rod shaped seen individually or in short chains or may appear as coccobacilli
- Difficult to stain and may even appear as gram-negative
- Motile at 28C by peritrichous flagella, not very motile at 37C
- Buffered Listeria Enrichment Broth
- Supplements
- Nalidixic acid: inhibits Gram negative spp.
- Does not ininhibit Pseudomonas or Proteus spp.
- Acriflavine: inhibits many other Gram (+) bacteria, parasites, and fungi
- Cycloheximide: inhibits yeasts and molds
- Very toxic
- Can be substituted by pimaricin (a.k.a. matamycin)
- Umbrella Motility
- Although all are considered to be potentially virulent, serovars 4b, 1/2b, and 1/2a account for 96% of human disease.
42
Q
Corynebacterium General Characteristics
A
- For C. diphtherias to cause diphtheria an exotoxin must be produced.
- It is a heat-labile polypeptide produced during lysogeny of a β phage that carries the “tox” gene.
- Alkaline pH of 7.8- 8.0, aerobic conditions, and a low
- environmental iron level are essential for toxin production
- (occurs late in the growth of the organism).
- The toxin inhibits protein synthesis
- C. ulcerans toxigenic strains may produce a disease
- similar to, but less severe than diphtheria.
- J-K Group commonly cause infections in those with
- underlying disease.
- Diseases include bacteremia, meningitis, peritonitis, wound
- infections, etc.
- It is becoming more and more of a problem.
- C. pseudotuberculosis found in those with exposure to
- animals.
- Can cause pneumonia or lymphadenitis.
- Produces a different exotoxin than C. diphtheriae.
43
Q
Corynebacterium ID
A
- Gram positive rods
- Catalase positive
- Non-acid fast
- Non-spore forming
- Aerobic or facultative anaerobic
- Fastidious
- Corynebacterium diphtheriae and diphtheroids (look like C. diphtheriae) are Gram positive club shaped rods.
- Loeffler‘s agar slant contains serum and
egg that enhance the formation of metachromatic granules (polymerized polyphosphoric acid) in C. diphtheriae. Also called Babes-Ernst granules.
They are visualized by staining with methylene blue. - A medium containing tellurite should be used to select for Corynebacterium and other gram positive organisms while it inhibits gram negative organisms. Two kinds are used: Cystine tellurite which has a longer shelf life.
- Elek plate: To prove that an isolate can cause
diphtheria, one must
demonstrate toxin production. - Tinsdale medium helps to differentiate amongst the Corynebacterium. Colonies on either appear black or gray due to tellurite reduction.
- 3 morphological types of C. diphtheriae are found on tellurite containing media:
- Mitis – black colonies with a gray periphery
- Gravis – large, gray colonies
- Intermedius – small, dull gray to black.
- All produce an immunologically identical toxin.
- Incubation -35-370 C for 24 hours.
- They prefer a pH of 7.8-8.0 for good growth.
- They require access to oxygen (poor AnO2 growth).
- Biochemistry
- Catalase +
- Non-motile
- C. ulcerans is urease + vs C. dphtheriae which is -; C. pseudotuberculosis is usually +
44
Q
Pasteurella sp
A
- Gram-negative coccobacilli or rods; bipolar staining
- Nonmotile; Facultatively anaerobic
- related to Actinobacter and Haemophilus
- Exist in the upper respiratory and GI tract of cats, dogs, domesticated and wild animals
- Species of importance : P. multocida, P.haemolytica, P.
- pneumotropica, P.ureae
- Pasteurella multocida: causative agent in human infection
45
Q
Pasteurella Medical Significance
A
- Zoonosis, virulent to animals and birds
- Fowl Cholera in Poultry
- Atrophic rhinitis in Pigs
- Shipping fever
- Bovine hemorrhagic septicemia
- human infections
- Local abscess
- Meningitis
- RT infections
- Animal Bites
46
Q
Pasteurella ID
A
- Specimens
- Swabs from bite wounds
- CSF in case of meningitis
- Secretions or sputum in case of RT infections
- Culture
- Blood agar
- Chocolate agar
- Microscopy Gram staining reveals GNCB
- Identification
- Cultural and Biochemical tests
- Catalase, oxidase +
- Indole +
- Urease -
- ODC +
- Growth on MacConkey -
- Acid from sucrose, mannitol +
47
Q
*The Genus
Capnocytophaga*
A
- Thin to slender gram-negative bacilli
- Tapered ends
- Cytochrome oxidase-variable; gliding motility
- “Capnocytophaga” [eater of CO2]
- Found as oropharyngeal flora in humans and other primates
- Pathogenic for humans
- rRNA superfamily V (“Cytophaga – Flavobacterium - Bacteroides” group
48
Q
Capnocytophaga medical significance
A
- Risk Factors (all)
- Dog ownership or contact
- Snoggling
- Underlying disease
- Asplenia
- Physician Awareness
- Patient Awareness
- Laboratory ID
- Conventional methods: SLOW
49
Q
Streptobacillus moniliformis General Characteristics
A
- Pleomorphic, facultatively anaerobic, gram-negative bacterium
- Causes two diseases
- Haverhill fever (rare)
- Associated with consumption of contaminated milk, water
- High incidence of pharyngitis with vomiting
- Rat-bite fever (common)
- Abrupt onset of high fever, headaches, arthralgia
- Rashes develop over extremities (palms, soles)
- Diagnosis is dependent upon:
- A good medical history (rat or animal exposure)
- Using optimal culture conditions to recover bacteria from blood, aspirates, or wounds
50
Q
S. moniliformis – Laboratory Identification
A
- Requires 10% - 20% serum for growth
- GNB in chains, filaments, sometimes with bulbous swellings
- Growth in thioglycollate broth producing “puff balls”
- Positive DFA test with polyclonal ab to S. moniliformis
- Rapid ID:
- PCR/ESI – MS
- 16S rRNA
51
Q
Erysipelothrix rhusiopathiae General Characteristics
A
- ‘Erysipelas’ [a disease] and ‘thrix’ [a hair or thread]; ‘rhusius’ [reddish] and ‘pathus’ [disease]: ‘erysipelas thread of red disease’
- Gram-positive rods [can decolorize easily]
- Slender rods with rounded ends; can form long filaments, short chains or in pairs in a “V” formation
- Non-motile
- Oxidase and catalase-negative
- Ecologic habitat: marine fish, molluscs, birds, and farm animals incl. swine, sheep, cattle, and horses
- Member of the Fimicutes, family Erysipelothricaceae
52
Q
E. rhusiopathiae Infections
A
- Causes three major syndromes:
- Erysipeloid (cutaneous form) resembling cellulitis
- Usually on hands or fingers
- Well-defined lesion, slightly raised, violaceous zone
- Diffuse cutaneous form
- More generalized than cutaneous; bullae may form
- Fever common plus joint pain
- Blood cultures are often negative
- Septicemia w/wo endocarditis
53
Q
*E. rhusiopathiae –
Laboratory ID*
A
- Facultatively anaerobic
- On TSA, colonies are very small after 24-48h incubation
- Can produce α-hemolysis on BAP
- Produces H2S on TSI
- “Test tube brush” growth in gelatin stab [no gelatinase]
- Most often confused with Listeria
54
Q
Streptococcus Iniae Significance
A
- Cellulitis
- Endocarditis, meningitis, arthritis
- aquaculture in south east asia
55
Q
S. iniae – Laboratory Identification
A
- Gram-positive, β-hemolytic
- Non-motile cocci
- PYR, CAMP, ADH, and Esc+
- Often mis-ID by conventional/rapid systems
- Rapid ID:
- 16S rRNA
- Cpn60
56
Q
HACEK
A
- Fastidious, Gram-negative bacilli
- Require an increased CO2 (5%-10%) environment
- Indigenous to the oral cavity / upper respiratory tract
- Opportunists in immunocompromised hosts
57
Q
Aggregatibacter aphrophilus
A
- Capnophilic, fermentative, non-motile, gram-negative coccobacillus
- Some strains require “V” factor (NAD)
- Oxidase-negative, catalase-negative
- Acid produced from: glucose, maltose, sucrose, lactose, and trehalose
- ONPG-positive
- ADH, LDC, and ODC-negative; urea-negative
58
Q
Aggregatibacter actinomycecomitans
A
- Capnophilic, gram-negative, non-motile coccobacilli
- Fermentative, fails to grow on MacConkey or enteric media
- Oxidase-negative, catalase-positive
- Does not require “X” or “V” factor for growth
- ONPG-negative
- ODC, LDC, and ADH-negative; urea-negative
59
Q
Cardiobacterium hominis
A
- Capnophilic (5%-7% CO2), gram-negative but can be gram-variable; non-motile
- Highly pleomorphic, cells may appear swollen with a tteardrop, dumbbell and lollypop-shap)ed cells. Can form rosettes from blood cultures.
- Oxidase-positive, catalase-negative; indole-positive
- Pitting variable on chocolate agar; often requires 48 – 72 hrs growth
- Grows on chocolate agar but not on MacConkey agar
60
Q
Eikenella corrodens
A
- Fastidious coccobacilli
- Gram negative
- Grow best with increased CO2 and hemin
- Non-motile
- Oxidase positive
- Nonsaccharolytic
- Resemble Moraxella sp.
- Catalase-negative
- Often produce yellow pigment
- 45% of isolates pit or corrode the surface of the agar
- In broth media, they may adhere to sides of the tube
- and produce granules
- Bleach-like odor given off from agar surface
61
Q
Kingella kingae
A
- Coccobacillary to short rods appearing
- in pairs and short chains
- Nonmotile
- Nutritionally fastidious
- Oxidase positive, catalase-negative
- Ferments glucose, maltose not sucrose
- May produce yellow-brown pigment
- May pit the agar
- Isolated from blood, bone, joint fluid, urine and wounds
- Most isolates from children <5 years
- Susceptible to penicillin and most antibiotics
62
Q
HACEK CHART
A
